2007-10-16 23:29:46 -07:00
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/* Basic authentication token and access key management
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2005-04-16 15:20:36 -07:00
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*
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2008-04-29 01:01:31 -07:00
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* Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
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2005-04-16 15:20:36 -07:00
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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2006-06-27 02:53:54 -07:00
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#include <linux/poison.h>
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2005-04-16 15:20:36 -07:00
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#include <linux/sched.h>
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#include <linux/slab.h>
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2005-10-30 16:02:44 -07:00
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#include <linux/security.h>
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2005-04-16 15:20:36 -07:00
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#include <linux/workqueue.h>
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2006-06-26 00:24:54 -07:00
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#include <linux/random.h>
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2005-04-16 15:20:36 -07:00
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#include <linux/err.h>
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2009-02-26 17:27:38 -07:00
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#include <linux/user_namespace.h>
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2005-04-16 15:20:36 -07:00
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#include "internal.h"
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2011-08-22 06:09:11 -07:00
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struct kmem_cache *key_jar;
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2005-04-16 15:20:36 -07:00
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struct rb_root key_serial_tree; /* tree of keys indexed by serial */
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DEFINE_SPINLOCK(key_serial_lock);
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struct rb_root key_user_tree; /* tree of quota records indexed by UID */
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DEFINE_SPINLOCK(key_user_lock);
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2008-04-29 01:01:32 -07:00
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unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
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unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
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unsigned int key_quota_maxkeys = 200; /* general key count quota */
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unsigned int key_quota_maxbytes = 20000; /* general key space quota */
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2005-04-16 15:20:36 -07:00
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static LIST_HEAD(key_types_list);
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static DECLARE_RWSEM(key_types_sem);
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2011-01-20 09:38:33 -07:00
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/* We serialise key instantiation and link */
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2007-10-16 23:29:46 -07:00
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DEFINE_MUTEX(key_construction_mutex);
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2005-04-16 15:20:36 -07:00
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#ifdef KEY_DEBUGGING
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void __key_check(const struct key *key)
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{
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printk("__key_check: key %p {%08x} should be {%08x}\n",
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key, key->magic, KEY_DEBUG_MAGIC);
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BUG();
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}
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#endif
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/*
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2011-01-20 09:38:33 -07:00
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* Get the key quota record for a user, allocating a new record if one doesn't
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* already exist.
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2005-04-16 15:20:36 -07:00
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*/
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2009-02-26 17:27:38 -07:00
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struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
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2005-04-16 15:20:36 -07:00
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{
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struct key_user *candidate = NULL, *user;
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struct rb_node *parent = NULL;
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struct rb_node **p;
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2011-01-20 09:38:33 -07:00
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try_again:
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2005-04-16 15:20:36 -07:00
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p = &key_user_tree.rb_node;
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spin_lock(&key_user_lock);
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/* search the tree for a user record with a matching UID */
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while (*p) {
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parent = *p;
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user = rb_entry(parent, struct key_user, node);
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if (uid < user->uid)
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p = &(*p)->rb_left;
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else if (uid > user->uid)
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p = &(*p)->rb_right;
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2009-02-26 17:27:38 -07:00
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else if (user_ns < user->user_ns)
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p = &(*p)->rb_left;
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else if (user_ns > user->user_ns)
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p = &(*p)->rb_right;
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2005-04-16 15:20:36 -07:00
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else
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goto found;
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}
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/* if we get here, we failed to find a match in the tree */
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if (!candidate) {
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/* allocate a candidate user record if we don't already have
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* one */
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spin_unlock(&key_user_lock);
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user = NULL;
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candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
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if (unlikely(!candidate))
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goto out;
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/* the allocation may have scheduled, so we need to repeat the
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* search lest someone else added the record whilst we were
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* asleep */
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goto try_again;
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}
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/* if we get here, then the user record still hadn't appeared on the
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* second pass - so we use the candidate record */
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atomic_set(&candidate->usage, 1);
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atomic_set(&candidate->nkeys, 0);
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atomic_set(&candidate->nikeys, 0);
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candidate->uid = uid;
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2009-02-26 17:27:38 -07:00
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candidate->user_ns = get_user_ns(user_ns);
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2005-04-16 15:20:36 -07:00
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candidate->qnkeys = 0;
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candidate->qnbytes = 0;
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spin_lock_init(&candidate->lock);
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2007-10-16 23:29:46 -07:00
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mutex_init(&candidate->cons_lock);
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2005-04-16 15:20:36 -07:00
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rb_link_node(&candidate->node, parent, p);
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rb_insert_color(&candidate->node, &key_user_tree);
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spin_unlock(&key_user_lock);
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user = candidate;
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goto out;
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/* okay - we found a user record for this UID */
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2011-01-20 09:38:33 -07:00
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found:
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2005-04-16 15:20:36 -07:00
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atomic_inc(&user->usage);
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spin_unlock(&key_user_lock);
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2005-11-07 02:01:35 -07:00
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kfree(candidate);
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2011-01-20 09:38:33 -07:00
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out:
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2005-04-16 15:20:36 -07:00
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return user;
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2011-01-20 09:38:27 -07:00
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}
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2005-04-16 15:20:36 -07:00
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/*
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2011-01-20 09:38:33 -07:00
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* Dispose of a user structure
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2005-04-16 15:20:36 -07:00
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*/
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void key_user_put(struct key_user *user)
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{
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if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
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rb_erase(&user->node, &key_user_tree);
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spin_unlock(&key_user_lock);
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2009-02-26 17:27:38 -07:00
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put_user_ns(user->user_ns);
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2005-04-16 15:20:36 -07:00
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kfree(user);
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}
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2011-01-20 09:38:27 -07:00
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}
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2005-04-16 15:20:36 -07:00
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/*
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2011-01-20 09:38:33 -07:00
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* Allocate a serial number for a key. These are assigned randomly to avoid
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* security issues through covert channel problems.
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2005-04-16 15:20:36 -07:00
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*/
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static inline void key_alloc_serial(struct key *key)
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{
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struct rb_node *parent, **p;
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struct key *xkey;
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2006-06-26 00:24:54 -07:00
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/* propose a random serial number and look for a hole for it in the
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2005-04-16 15:20:36 -07:00
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* serial number tree */
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2006-06-26 00:24:54 -07:00
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do {
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get_random_bytes(&key->serial, sizeof(key->serial));
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key->serial >>= 1; /* negative numbers are not permitted */
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} while (key->serial < 3);
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spin_lock(&key_serial_lock);
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2005-04-16 15:20:36 -07:00
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2007-02-06 06:45:51 -07:00
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attempt_insertion:
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2005-04-16 15:20:36 -07:00
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parent = NULL;
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p = &key_serial_tree.rb_node;
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while (*p) {
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parent = *p;
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xkey = rb_entry(parent, struct key, serial_node);
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if (key->serial < xkey->serial)
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p = &(*p)->rb_left;
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else if (key->serial > xkey->serial)
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p = &(*p)->rb_right;
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else
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goto serial_exists;
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}
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2007-02-06 06:45:51 -07:00
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/* we've found a suitable hole - arrange for this key to occupy it */
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rb_link_node(&key->serial_node, parent, p);
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rb_insert_color(&key->serial_node, &key_serial_tree);
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spin_unlock(&key_serial_lock);
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return;
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2005-04-16 15:20:36 -07:00
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/* we found a key with the proposed serial number - walk the tree from
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* that point looking for the next unused serial number */
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2006-06-26 00:24:54 -07:00
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serial_exists:
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2005-04-16 15:20:36 -07:00
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for (;;) {
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2006-06-26 00:24:54 -07:00
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key->serial++;
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2007-02-06 06:45:51 -07:00
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if (key->serial < 3) {
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key->serial = 3;
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goto attempt_insertion;
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}
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2005-04-16 15:20:36 -07:00
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parent = rb_next(parent);
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if (!parent)
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2007-02-06 06:45:51 -07:00
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goto attempt_insertion;
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2005-04-16 15:20:36 -07:00
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xkey = rb_entry(parent, struct key, serial_node);
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if (key->serial < xkey->serial)
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2007-02-06 06:45:51 -07:00
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goto attempt_insertion;
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2005-04-16 15:20:36 -07:00
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}
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2011-01-20 09:38:27 -07:00
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}
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2005-04-16 15:20:36 -07:00
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2011-01-20 09:38:33 -07:00
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/**
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* key_alloc - Allocate a key of the specified type.
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* @type: The type of key to allocate.
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* @desc: The key description to allow the key to be searched out.
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* @uid: The owner of the new key.
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* @gid: The group ID for the new key's group permissions.
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* @cred: The credentials specifying UID namespace.
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* @perm: The permissions mask of the new key.
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* @flags: Flags specifying quota properties.
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*
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* Allocate a key of the specified type with the attributes given. The key is
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* returned in an uninstantiated state and the caller needs to instantiate the
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* key before returning.
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*
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* The user's key count quota is updated to reflect the creation of the key and
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* the user's key data quota has the default for the key type reserved. The
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* instantiation function should amend this as necessary. If insufficient
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* quota is available, -EDQUOT will be returned.
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*
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* The LSM security modules can prevent a key being created, in which case
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* -EACCES will be returned.
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*
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* Returns a pointer to the new key if successful and an error code otherwise.
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*
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* Note that the caller needs to ensure the key type isn't uninstantiated.
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* Internally this can be done by locking key_types_sem. Externally, this can
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* be done by either never unregistering the key type, or making sure
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* key_alloc() calls don't race with module unloading.
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2005-04-16 15:20:36 -07:00
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*/
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struct key *key_alloc(struct key_type *type, const char *desc,
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CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
uid_t uid, gid_t gid, const struct cred *cred,
|
2006-06-26 00:24:50 -07:00
|
|
|
key_perm_t perm, unsigned long flags)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
|
|
|
struct key_user *user = NULL;
|
|
|
|
struct key *key;
|
|
|
|
size_t desclen, quotalen;
|
2005-10-30 16:02:44 -07:00
|
|
|
int ret;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
key = ERR_PTR(-EINVAL);
|
|
|
|
if (!desc || !*desc)
|
|
|
|
goto error;
|
|
|
|
|
2011-03-07 08:05:59 -07:00
|
|
|
if (type->vet_description) {
|
|
|
|
ret = type->vet_description(desc);
|
|
|
|
if (ret < 0) {
|
|
|
|
key = ERR_PTR(ret);
|
|
|
|
goto error;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
desclen = strlen(desc) + 1;
|
|
|
|
quotalen = desclen + type->def_datalen;
|
|
|
|
|
|
|
|
/* get hold of the key tracking for this user */
|
2009-02-26 17:27:38 -07:00
|
|
|
user = key_user_lookup(uid, cred->user->user_ns);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!user)
|
|
|
|
goto no_memory_1;
|
|
|
|
|
|
|
|
/* check that the user's quota permits allocation of another key and
|
|
|
|
* its description */
|
2006-06-26 00:24:50 -07:00
|
|
|
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
|
2008-04-29 01:01:32 -07:00
|
|
|
unsigned maxkeys = (uid == 0) ?
|
|
|
|
key_quota_root_maxkeys : key_quota_maxkeys;
|
|
|
|
unsigned maxbytes = (uid == 0) ?
|
|
|
|
key_quota_root_maxbytes : key_quota_maxbytes;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
spin_lock(&user->lock);
|
2006-06-26 00:24:50 -07:00
|
|
|
if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
|
2008-04-29 01:01:32 -07:00
|
|
|
if (user->qnkeys + 1 >= maxkeys ||
|
|
|
|
user->qnbytes + quotalen >= maxbytes ||
|
|
|
|
user->qnbytes + quotalen < user->qnbytes)
|
2006-06-26 00:24:50 -07:00
|
|
|
goto no_quota;
|
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
user->qnkeys++;
|
|
|
|
user->qnbytes += quotalen;
|
|
|
|
spin_unlock(&user->lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* allocate and initialise the key and its description */
|
2006-12-06 21:33:17 -07:00
|
|
|
key = kmem_cache_alloc(key_jar, GFP_KERNEL);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!key)
|
|
|
|
goto no_memory_2;
|
|
|
|
|
|
|
|
if (desc) {
|
2006-12-06 21:33:47 -07:00
|
|
|
key->description = kmemdup(desc, desclen, GFP_KERNEL);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!key->description)
|
|
|
|
goto no_memory_3;
|
|
|
|
}
|
|
|
|
|
|
|
|
atomic_set(&key->usage, 1);
|
|
|
|
init_rwsem(&key->sem);
|
2011-11-16 04:15:54 -07:00
|
|
|
lockdep_set_class(&key->sem, &type->lock_class);
|
2005-04-16 15:20:36 -07:00
|
|
|
key->type = type;
|
|
|
|
key->user = user;
|
|
|
|
key->quotalen = quotalen;
|
|
|
|
key->datalen = type->def_datalen;
|
|
|
|
key->uid = uid;
|
|
|
|
key->gid = gid;
|
|
|
|
key->perm = perm;
|
|
|
|
key->flags = 0;
|
|
|
|
key->expiry = 0;
|
|
|
|
key->payload.data = NULL;
|
2005-10-30 16:02:44 -07:00
|
|
|
key->security = NULL;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2006-06-26 00:24:50 -07:00
|
|
|
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
|
2005-06-23 22:00:49 -07:00
|
|
|
key->flags |= 1 << KEY_FLAG_IN_QUOTA;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
memset(&key->type_data, 0, sizeof(key->type_data));
|
|
|
|
|
|
|
|
#ifdef KEY_DEBUGGING
|
|
|
|
key->magic = KEY_DEBUG_MAGIC;
|
|
|
|
#endif
|
|
|
|
|
2005-10-30 16:02:44 -07:00
|
|
|
/* let the security module know about the key */
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
ret = security_key_alloc(key, cred, flags);
|
2005-10-30 16:02:44 -07:00
|
|
|
if (ret < 0)
|
|
|
|
goto security_error;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/* publish the key by giving it a serial number */
|
|
|
|
atomic_inc(&user->nkeys);
|
|
|
|
key_alloc_serial(key);
|
|
|
|
|
2005-10-30 16:02:44 -07:00
|
|
|
error:
|
2005-04-16 15:20:36 -07:00
|
|
|
return key;
|
|
|
|
|
2005-10-30 16:02:44 -07:00
|
|
|
security_error:
|
|
|
|
kfree(key->description);
|
2005-04-16 15:20:36 -07:00
|
|
|
kmem_cache_free(key_jar, key);
|
2006-06-26 00:24:50 -07:00
|
|
|
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
|
2005-04-16 15:20:36 -07:00
|
|
|
spin_lock(&user->lock);
|
|
|
|
user->qnkeys--;
|
|
|
|
user->qnbytes -= quotalen;
|
|
|
|
spin_unlock(&user->lock);
|
|
|
|
}
|
|
|
|
key_user_put(user);
|
2005-10-30 16:02:44 -07:00
|
|
|
key = ERR_PTR(ret);
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
no_memory_3:
|
|
|
|
kmem_cache_free(key_jar, key);
|
|
|
|
no_memory_2:
|
2006-06-26 00:24:50 -07:00
|
|
|
if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
|
2005-10-30 16:02:44 -07:00
|
|
|
spin_lock(&user->lock);
|
|
|
|
user->qnkeys--;
|
|
|
|
user->qnbytes -= quotalen;
|
|
|
|
spin_unlock(&user->lock);
|
|
|
|
}
|
|
|
|
key_user_put(user);
|
|
|
|
no_memory_1:
|
2005-04-16 15:20:36 -07:00
|
|
|
key = ERR_PTR(-ENOMEM);
|
|
|
|
goto error;
|
|
|
|
|
2005-10-30 16:02:44 -07:00
|
|
|
no_quota:
|
2005-04-16 15:20:36 -07:00
|
|
|
spin_unlock(&user->lock);
|
|
|
|
key_user_put(user);
|
|
|
|
key = ERR_PTR(-EDQUOT);
|
|
|
|
goto error;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_alloc);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_payload_reserve - Adjust data quota reservation for the key's payload
|
|
|
|
* @key: The key to make the reservation for.
|
|
|
|
* @datalen: The amount of data payload the caller now wants.
|
|
|
|
*
|
|
|
|
* Adjust the amount of the owning user's key data quota that a key reserves.
|
|
|
|
* If the amount is increased, then -EDQUOT may be returned if there isn't
|
|
|
|
* enough free quota available.
|
|
|
|
*
|
|
|
|
* If successful, 0 is returned.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
int key_payload_reserve(struct key *key, size_t datalen)
|
|
|
|
{
|
2010-04-21 00:02:11 -07:00
|
|
|
int delta = (int)datalen - key->datalen;
|
2005-04-16 15:20:36 -07:00
|
|
|
int ret = 0;
|
|
|
|
|
|
|
|
key_check(key);
|
|
|
|
|
|
|
|
/* contemplate the quota adjustment */
|
2005-06-23 22:00:49 -07:00
|
|
|
if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
|
2008-04-29 01:01:32 -07:00
|
|
|
unsigned maxbytes = (key->user->uid == 0) ?
|
|
|
|
key_quota_root_maxbytes : key_quota_maxbytes;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
spin_lock(&key->user->lock);
|
|
|
|
|
|
|
|
if (delta > 0 &&
|
2008-04-29 01:01:32 -07:00
|
|
|
(key->user->qnbytes + delta >= maxbytes ||
|
|
|
|
key->user->qnbytes + delta < key->user->qnbytes)) {
|
2005-04-16 15:20:36 -07:00
|
|
|
ret = -EDQUOT;
|
|
|
|
}
|
|
|
|
else {
|
|
|
|
key->user->qnbytes += delta;
|
|
|
|
key->quotalen += delta;
|
|
|
|
}
|
|
|
|
spin_unlock(&key->user->lock);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* change the recorded data length if that didn't generate an error */
|
|
|
|
if (ret == 0)
|
|
|
|
key->datalen = datalen;
|
|
|
|
|
|
|
|
return ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_payload_reserve);
|
|
|
|
|
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Instantiate a key and link it into the target keyring atomically. Must be
|
|
|
|
* called with the target keyring's semaphore writelocked. The target key's
|
|
|
|
* semaphore need not be locked as instantiation is serialised by
|
|
|
|
* key_construction_mutex.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
static int __key_instantiate_and_link(struct key *key,
|
|
|
|
const void *data,
|
|
|
|
size_t datalen,
|
[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
struct key *keyring,
|
2010-04-30 06:32:39 -07:00
|
|
|
struct key *authkey,
|
2011-01-25 09:34:28 -07:00
|
|
|
unsigned long *_prealloc)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
|
|
|
int ret, awaken;
|
|
|
|
|
|
|
|
key_check(key);
|
|
|
|
key_check(keyring);
|
|
|
|
|
|
|
|
awaken = 0;
|
|
|
|
ret = -EBUSY;
|
|
|
|
|
2007-10-16 23:29:46 -07:00
|
|
|
mutex_lock(&key_construction_mutex);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* can't instantiate twice */
|
2005-06-23 22:00:49 -07:00
|
|
|
if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
|
2005-04-16 15:20:36 -07:00
|
|
|
/* instantiate the key */
|
|
|
|
ret = key->type->instantiate(key, data, datalen);
|
|
|
|
|
|
|
|
if (ret == 0) {
|
|
|
|
/* mark the key as being instantiated */
|
|
|
|
atomic_inc(&key->user->nikeys);
|
2005-06-23 22:00:49 -07:00
|
|
|
set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
awaken = 1;
|
|
|
|
|
|
|
|
/* and link it into the destination keyring */
|
|
|
|
if (keyring)
|
2010-04-30 06:32:39 -07:00
|
|
|
__key_link(keyring, key, _prealloc);
|
[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
|
|
|
|
/* disable the authorisation key */
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
if (authkey)
|
|
|
|
key_revoke(authkey);
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2007-10-16 23:29:46 -07:00
|
|
|
mutex_unlock(&key_construction_mutex);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* wake up anyone waiting for a key to be constructed */
|
|
|
|
if (awaken)
|
2007-10-16 23:29:46 -07:00
|
|
|
wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
return ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_instantiate_and_link - Instantiate a key and link it into the keyring.
|
|
|
|
* @key: The key to instantiate.
|
|
|
|
* @data: The data to use to instantiate the keyring.
|
|
|
|
* @datalen: The length of @data.
|
|
|
|
* @keyring: Keyring to create a link in on success (or NULL).
|
|
|
|
* @authkey: The authorisation token permitting instantiation.
|
|
|
|
*
|
|
|
|
* Instantiate a key that's in the uninstantiated state using the provided data
|
|
|
|
* and, if successful, link it in to the destination keyring if one is
|
|
|
|
* supplied.
|
|
|
|
*
|
|
|
|
* If successful, 0 is returned, the authorisation token is revoked and anyone
|
|
|
|
* waiting for the key is woken up. If the key was already instantiated,
|
|
|
|
* -EBUSY will be returned.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
int key_instantiate_and_link(struct key *key,
|
|
|
|
const void *data,
|
|
|
|
size_t datalen,
|
[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
struct key *keyring,
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
struct key *authkey)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
2011-01-25 09:34:28 -07:00
|
|
|
unsigned long prealloc;
|
2005-04-16 15:20:36 -07:00
|
|
|
int ret;
|
|
|
|
|
2010-04-30 06:32:39 -07:00
|
|
|
if (keyring) {
|
|
|
|
ret = __key_link_begin(keyring, key->type, key->description,
|
|
|
|
&prealloc);
|
|
|
|
if (ret < 0)
|
|
|
|
return ret;
|
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2010-04-30 06:32:39 -07:00
|
|
|
ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey,
|
|
|
|
&prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
if (keyring)
|
2010-04-30 06:32:39 -07:00
|
|
|
__key_link_end(keyring, key->type, prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
return ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
EXPORT_SYMBOL(key_instantiate_and_link);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
2011-03-07 08:06:09 -07:00
|
|
|
* key_reject_and_link - Negatively instantiate a key and link it into the keyring.
|
2011-01-20 09:38:33 -07:00
|
|
|
* @key: The key to instantiate.
|
|
|
|
* @timeout: The timeout on the negative key.
|
2011-03-07 08:06:09 -07:00
|
|
|
* @error: The error to return when the key is hit.
|
2011-01-20 09:38:33 -07:00
|
|
|
* @keyring: Keyring to create a link in on success (or NULL).
|
|
|
|
* @authkey: The authorisation token permitting instantiation.
|
|
|
|
*
|
|
|
|
* Negatively instantiate a key that's in the uninstantiated state and, if
|
2011-03-07 08:06:09 -07:00
|
|
|
* successful, set its timeout and stored error and link it in to the
|
|
|
|
* destination keyring if one is supplied. The key and any links to the key
|
|
|
|
* will be automatically garbage collected after the timeout expires.
|
2011-01-20 09:38:33 -07:00
|
|
|
*
|
|
|
|
* Negative keys are used to rate limit repeated request_key() calls by causing
|
2011-03-07 08:06:09 -07:00
|
|
|
* them to return the stored error code (typically ENOKEY) until the negative
|
|
|
|
* key expires.
|
2011-01-20 09:38:33 -07:00
|
|
|
*
|
|
|
|
* If successful, 0 is returned, the authorisation token is revoked and anyone
|
|
|
|
* waiting for the key is woken up. If the key was already instantiated,
|
|
|
|
* -EBUSY will be returned.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2011-03-07 08:06:09 -07:00
|
|
|
int key_reject_and_link(struct key *key,
|
2005-04-16 15:20:36 -07:00
|
|
|
unsigned timeout,
|
2011-03-07 08:06:09 -07:00
|
|
|
unsigned error,
|
[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
struct key *keyring,
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
struct key *authkey)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
2011-01-25 09:34:28 -07:00
|
|
|
unsigned long prealloc;
|
2005-04-16 15:20:36 -07:00
|
|
|
struct timespec now;
|
2010-04-30 06:32:39 -07:00
|
|
|
int ret, awaken, link_ret = 0;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
key_check(key);
|
|
|
|
key_check(keyring);
|
|
|
|
|
|
|
|
awaken = 0;
|
|
|
|
ret = -EBUSY;
|
|
|
|
|
|
|
|
if (keyring)
|
2010-04-30 06:32:39 -07:00
|
|
|
link_ret = __key_link_begin(keyring, key->type,
|
|
|
|
key->description, &prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2007-10-16 23:29:46 -07:00
|
|
|
mutex_lock(&key_construction_mutex);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* can't instantiate twice */
|
2005-06-23 22:00:49 -07:00
|
|
|
if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
|
2005-04-16 15:20:36 -07:00
|
|
|
/* mark the key as being negatively instantiated */
|
|
|
|
atomic_inc(&key->user->nikeys);
|
2005-06-23 22:00:49 -07:00
|
|
|
set_bit(KEY_FLAG_NEGATIVE, &key->flags);
|
|
|
|
set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
|
2011-03-07 08:06:09 -07:00
|
|
|
key->type_data.reject_error = -error;
|
2005-04-16 15:20:36 -07:00
|
|
|
now = current_kernel_time();
|
|
|
|
key->expiry = now.tv_sec + timeout;
|
2009-09-14 09:26:13 -07:00
|
|
|
key_schedule_gc(key->expiry + key_gc_delay);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
awaken = 1;
|
|
|
|
|
|
|
|
ret = 0;
|
|
|
|
|
|
|
|
/* and link it into the destination keyring */
|
2010-04-30 06:32:39 -07:00
|
|
|
if (keyring && link_ret == 0)
|
|
|
|
__key_link(keyring, key, &prealloc);
|
[PATCH] Keys: Make request-key create an authorisation key
The attached patch makes the following changes:
(1) There's a new special key type called ".request_key_auth".
This is an authorisation key for when one process requests a key and
another process is started to construct it. This type of key cannot be
created by the user; nor can it be requested by kernel services.
Authorisation keys hold two references:
(a) Each refers to a key being constructed. When the key being
constructed is instantiated the authorisation key is revoked,
rendering it of no further use.
(b) The "authorising process". This is either:
(i) the process that called request_key(), or:
(ii) if the process that called request_key() itself had an
authorisation key in its session keyring, then the authorising
process referred to by that authorisation key will also be
referred to by the new authorisation key.
This means that the process that initiated a chain of key requests
will authorise the lot of them, and will, by default, wind up with
the keys obtained from them in its keyrings.
(2) request_key() creates an authorisation key which is then passed to
/sbin/request-key in as part of a new session keyring.
(3) When request_key() is searching for a key to hand back to the caller, if
it comes across an authorisation key in the session keyring of the
calling process, it will also search the keyrings of the process
specified therein and it will use the specified process's credentials
(fsuid, fsgid, groups) to do that rather than the calling process's
credentials.
This allows a process started by /sbin/request-key to find keys belonging
to the authorising process.
(4) A key can be read, even if the process executing KEYCTL_READ doesn't have
direct read or search permission if that key is contained within the
keyrings of a process specified by an authorisation key found within the
calling process's session keyring, and is searchable using the
credentials of the authorising process.
This allows a process started by /sbin/request-key to read keys belonging
to the authorising process.
(5) The magic KEY_SPEC_*_KEYRING key IDs when passed to KEYCTL_INSTANTIATE or
KEYCTL_NEGATE will specify a keyring of the authorising process, rather
than the process doing the instantiation.
(6) One of the process keyrings can be nominated as the default to which
request_key() should attach new keys if not otherwise specified. This is
done with KEYCTL_SET_REQKEY_KEYRING and one of the KEY_REQKEY_DEFL_*
constants. The current setting can also be read using this call.
(7) request_key() is partially interruptible. If it is waiting for another
process to finish constructing a key, it can be interrupted. This permits
a request-key cycle to be broken without recourse to rebooting.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-Off-By: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 22:00:56 -07:00
|
|
|
|
|
|
|
/* disable the authorisation key */
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
if (authkey)
|
|
|
|
key_revoke(authkey);
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
|
2007-10-16 23:29:46 -07:00
|
|
|
mutex_unlock(&key_construction_mutex);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
if (keyring)
|
2010-04-30 06:32:39 -07:00
|
|
|
__key_link_end(keyring, key->type, prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* wake up anyone waiting for a key to be constructed */
|
|
|
|
if (awaken)
|
2007-10-16 23:29:46 -07:00
|
|
|
wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2010-04-30 06:32:39 -07:00
|
|
|
return ret == 0 ? link_ret : ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2011-03-07 08:06:09 -07:00
|
|
|
EXPORT_SYMBOL(key_reject_and_link);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_put - Discard a reference to a key.
|
|
|
|
* @key: The key to discard a reference from.
|
|
|
|
*
|
|
|
|
* Discard a reference to a key, and when all the references are gone, we
|
|
|
|
* schedule the cleanup task to come and pull it out of the tree in process
|
|
|
|
* context at some later time.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
void key_put(struct key *key)
|
|
|
|
{
|
|
|
|
if (key) {
|
|
|
|
key_check(key);
|
|
|
|
|
|
|
|
if (atomic_dec_and_test(&key->usage))
|
KEYS: Correctly destroy key payloads when their keytype is removed
unregister_key_type() has code to mark a key as dead and make it unavailable in
one loop and then destroy all those unavailable key payloads in the next loop.
However, the loop to mark keys dead renders the key undetectable to the second
loop by changing the key type pointer also.
Fix this by the following means:
(1) The key code has two garbage collectors: one deletes unreferenced keys and
the other alters keyrings to delete links to old dead, revoked and expired
keys. They can end up holding each other up as both want to scan the key
serial tree under spinlock. Combine these into a single routine.
(2) Move the dead key marking, dead link removal and dead key removal into the
garbage collector as a three phase process running over the three cycles
of the normal garbage collection procedure. This is tracked by the
KEY_GC_REAPING_DEAD_1, _2 and _3 state flags.
unregister_key_type() then just unlinks the key type from the list, wakes
up the garbage collector and waits for the third phase to complete.
(3) Downgrade the key types sem in unregister_key_type() once it has deleted
the key type from the list so that it doesn't block the keyctl() syscall.
(4) Dead keys that cannot be simply removed in the third phase have their
payloads destroyed with the key's semaphore write-locked to prevent
interference by the keyctl() syscall. There should be no in-kernel users
of dead keys of that type by the point of unregistration, though keyctl()
may be holding a reference.
(5) Only perform timer recalculation in the GC if the timer actually expired.
If it didn't, we'll get another cycle when it goes off - and if the key
that actually triggered it has been removed, it's not a problem.
(6) Only garbage collect link if the timer expired or if we're doing dead key
clean up phase 2.
(7) As only key_garbage_collector() is permitted to use rb_erase() on the key
serial tree, it doesn't need to revalidate its cursor after dropping the
spinlock as the node the cursor points to must still exist in the tree.
(8) Drop the spinlock in the GC if there is contention on it or if we need to
reschedule. After dealing with that, get the spinlock again and resume
scanning.
This has been tested in the following ways:
(1) Run the keyutils testsuite against it.
(2) Using the AF_RXRPC and RxKAD modules to test keytype removal:
Load the rxrpc_s key type:
# insmod /tmp/af-rxrpc.ko
# insmod /tmp/rxkad.ko
Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c):
# /tmp/listen &
[1] 8173
Find the key:
# grep rxrpc_s /proc/keys
091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2
Link it to a session keyring, preferably one with a higher serial number:
# keyctl link 0x20e36251 @s
Kill the process (the key should remain as it's linked to another place):
# fg
/tmp/listen
^C
Remove the key type:
rmmod rxkad
rmmod af-rxrpc
This can be made a more effective test by altering the following part of
the patch:
if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
/* Make sure everyone revalidates their keys if we marked a
* bunch as being dead and make sure all keyring ex-payloads
* are destroyed.
*/
kdebug("dead sync");
synchronize_rcu();
To call synchronize_rcu() in GC phase 1 instead. That causes that the
keyring's old payload content to hang around longer until it's RCU
destroyed - which usually happens after GC phase 3 is complete. This
allows the destroy_dead_key branch to be tested.
Reported-by: Benjamin Coddington <bcodding@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-22 06:09:36 -07:00
|
|
|
queue_work(system_nrt_wq, &key_gc_work);
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_put);
|
|
|
|
|
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Find a key by its serial number.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
struct key *key_lookup(key_serial_t id)
|
|
|
|
{
|
|
|
|
struct rb_node *n;
|
|
|
|
struct key *key;
|
|
|
|
|
|
|
|
spin_lock(&key_serial_lock);
|
|
|
|
|
|
|
|
/* search the tree for the specified key */
|
|
|
|
n = key_serial_tree.rb_node;
|
|
|
|
while (n) {
|
|
|
|
key = rb_entry(n, struct key, serial_node);
|
|
|
|
|
|
|
|
if (id < key->serial)
|
|
|
|
n = n->rb_left;
|
|
|
|
else if (id > key->serial)
|
|
|
|
n = n->rb_right;
|
|
|
|
else
|
|
|
|
goto found;
|
|
|
|
}
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
not_found:
|
2005-04-16 15:20:36 -07:00
|
|
|
key = ERR_PTR(-ENOKEY);
|
|
|
|
goto error;
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
found:
|
2009-09-02 01:13:45 -07:00
|
|
|
/* pretend it doesn't exist if it is awaiting deletion */
|
|
|
|
if (atomic_read(&key->usage) == 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
goto not_found;
|
|
|
|
|
|
|
|
/* this races with key_put(), but that doesn't matter since key_put()
|
|
|
|
* doesn't actually change the key
|
|
|
|
*/
|
|
|
|
atomic_inc(&key->usage);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
error:
|
2005-04-16 15:20:36 -07:00
|
|
|
spin_unlock(&key_serial_lock);
|
|
|
|
return key;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Find and lock the specified key type against removal.
|
|
|
|
*
|
|
|
|
* We return with the sem read-locked if successful. If the type wasn't
|
|
|
|
* available -ENOKEY is returned instead.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
struct key_type *key_type_lookup(const char *type)
|
|
|
|
{
|
|
|
|
struct key_type *ktype;
|
|
|
|
|
|
|
|
down_read(&key_types_sem);
|
|
|
|
|
|
|
|
/* look up the key type to see if it's one of the registered kernel
|
|
|
|
* types */
|
|
|
|
list_for_each_entry(ktype, &key_types_list, link) {
|
|
|
|
if (strcmp(ktype->name, type) == 0)
|
|
|
|
goto found_kernel_type;
|
|
|
|
}
|
|
|
|
|
|
|
|
up_read(&key_types_sem);
|
|
|
|
ktype = ERR_PTR(-ENOKEY);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
found_kernel_type:
|
2005-04-16 15:20:36 -07:00
|
|
|
return ktype;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2012-02-24 12:14:50 -07:00
|
|
|
void key_set_timeout(struct key *key, unsigned timeout)
|
|
|
|
{
|
|
|
|
struct timespec now;
|
|
|
|
time_t expiry = 0;
|
|
|
|
|
|
|
|
/* make the changes with the locks held to prevent races */
|
|
|
|
down_write(&key->sem);
|
|
|
|
|
|
|
|
if (timeout > 0) {
|
|
|
|
now = current_kernel_time();
|
|
|
|
expiry = now.tv_sec + timeout;
|
|
|
|
}
|
|
|
|
|
|
|
|
key->expiry = expiry;
|
|
|
|
key_schedule_gc(key->expiry + key_gc_delay);
|
|
|
|
|
|
|
|
up_write(&key->sem);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(key_set_timeout);
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Unlock a key type locked by key_type_lookup().
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
void key_type_put(struct key_type *ktype)
|
|
|
|
{
|
|
|
|
up_read(&key_types_sem);
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Attempt to update an existing key.
|
|
|
|
*
|
|
|
|
* The key is given to us with an incremented refcount that we need to discard
|
|
|
|
* if we get an error.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
static inline key_ref_t __key_update(key_ref_t key_ref,
|
|
|
|
const void *payload, size_t plen)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
2005-09-28 09:03:15 -07:00
|
|
|
struct key *key = key_ref_to_ptr(key_ref);
|
2005-04-16 15:20:36 -07:00
|
|
|
int ret;
|
|
|
|
|
|
|
|
/* need write permission on the key to update it */
|
2005-10-30 16:02:44 -07:00
|
|
|
ret = key_permission(key_ref, KEY_WRITE);
|
|
|
|
if (ret < 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
|
|
|
|
|
|
|
ret = -EEXIST;
|
|
|
|
if (!key->type->update)
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
down_write(&key->sem);
|
|
|
|
|
|
|
|
ret = key->type->update(key, payload, plen);
|
2005-06-23 22:00:49 -07:00
|
|
|
if (ret == 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
/* updating a negative key instantiates it */
|
2005-06-23 22:00:49 -07:00
|
|
|
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
up_write(&key->sem);
|
|
|
|
|
|
|
|
if (ret < 0)
|
|
|
|
goto error;
|
2005-09-28 09:03:15 -07:00
|
|
|
out:
|
|
|
|
return key_ref;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
error:
|
2005-04-16 15:20:36 -07:00
|
|
|
key_put(key);
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(ret);
|
2005-04-16 15:20:36 -07:00
|
|
|
goto out;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_create_or_update - Update or create and instantiate a key.
|
|
|
|
* @keyring_ref: A pointer to the destination keyring with possession flag.
|
|
|
|
* @type: The type of key.
|
|
|
|
* @description: The searchable description for the key.
|
|
|
|
* @payload: The data to use to instantiate or update the key.
|
|
|
|
* @plen: The length of @payload.
|
|
|
|
* @perm: The permissions mask for a new key.
|
|
|
|
* @flags: The quota flags for a new key.
|
|
|
|
*
|
|
|
|
* Search the destination keyring for a key of the same description and if one
|
|
|
|
* is found, update it, otherwise create and instantiate a new one and create a
|
|
|
|
* link to it from that keyring.
|
|
|
|
*
|
|
|
|
* If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
|
|
|
|
* concocted.
|
|
|
|
*
|
|
|
|
* Returns a pointer to the new key if successful, -ENODEV if the key type
|
|
|
|
* wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
|
|
|
|
* caller isn't permitted to modify the keyring or the LSM did not permit
|
|
|
|
* creation of the key.
|
|
|
|
*
|
|
|
|
* On success, the possession flag from the keyring ref will be tacked on to
|
|
|
|
* the key ref before it is returned.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref_t key_create_or_update(key_ref_t keyring_ref,
|
|
|
|
const char *type,
|
|
|
|
const char *description,
|
|
|
|
const void *payload,
|
|
|
|
size_t plen,
|
2008-04-29 01:01:28 -07:00
|
|
|
key_perm_t perm,
|
2006-06-26 00:24:50 -07:00
|
|
|
unsigned long flags)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
2011-01-25 09:34:28 -07:00
|
|
|
unsigned long prealloc;
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
const struct cred *cred = current_cred();
|
2005-04-16 15:20:36 -07:00
|
|
|
struct key_type *ktype;
|
2005-09-28 09:03:15 -07:00
|
|
|
struct key *keyring, *key = NULL;
|
|
|
|
key_ref_t key_ref;
|
2005-04-16 15:20:36 -07:00
|
|
|
int ret;
|
|
|
|
|
|
|
|
/* look up the key type to see if it's one of the registered kernel
|
|
|
|
* types */
|
|
|
|
ktype = key_type_lookup(type);
|
|
|
|
if (IS_ERR(ktype)) {
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(-ENODEV);
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
|
|
|
}
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(-EINVAL);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!ktype->match || !ktype->instantiate)
|
|
|
|
goto error_2;
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
keyring = key_ref_to_ptr(keyring_ref);
|
|
|
|
|
|
|
|
key_check(keyring);
|
|
|
|
|
2006-04-10 07:15:21 -07:00
|
|
|
key_ref = ERR_PTR(-ENOTDIR);
|
|
|
|
if (keyring->type != &key_type_keyring)
|
|
|
|
goto error_2;
|
|
|
|
|
2010-04-30 06:32:39 -07:00
|
|
|
ret = __key_link_begin(keyring, ktype, description, &prealloc);
|
|
|
|
if (ret < 0)
|
|
|
|
goto error_2;
|
2005-09-28 09:03:15 -07:00
|
|
|
|
|
|
|
/* if we're going to allocate a new key, we're going to have
|
|
|
|
* to modify the keyring */
|
2005-10-30 16:02:44 -07:00
|
|
|
ret = key_permission(keyring_ref, KEY_WRITE);
|
|
|
|
if (ret < 0) {
|
|
|
|
key_ref = ERR_PTR(ret);
|
2005-09-28 09:03:15 -07:00
|
|
|
goto error_3;
|
2005-10-30 16:02:44 -07:00
|
|
|
}
|
2005-09-28 09:03:15 -07:00
|
|
|
|
2006-03-25 04:06:52 -07:00
|
|
|
/* if it's possible to update this type of key, search for an existing
|
|
|
|
* key of the same type and description in the destination keyring and
|
|
|
|
* update that instead if possible
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2006-03-25 04:06:52 -07:00
|
|
|
if (ktype->update) {
|
|
|
|
key_ref = __keyring_search_one(keyring_ref, ktype, description,
|
|
|
|
0);
|
|
|
|
if (!IS_ERR(key_ref))
|
|
|
|
goto found_matching_key;
|
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2008-04-29 01:01:28 -07:00
|
|
|
/* if the client doesn't provide, decide on the permissions we want */
|
|
|
|
if (perm == KEY_PERM_UNDEF) {
|
|
|
|
perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
|
|
|
|
perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2008-04-29 01:01:28 -07:00
|
|
|
if (ktype->read)
|
|
|
|
perm |= KEY_POS_READ | KEY_USR_READ;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2008-04-29 01:01:28 -07:00
|
|
|
if (ktype == &key_type_keyring || ktype->update)
|
|
|
|
perm |= KEY_USR_WRITE;
|
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* allocate a new key */
|
CRED: Inaugurate COW credentials
Inaugurate copy-on-write credentials management. This uses RCU to manage the
credentials pointer in the task_struct with respect to accesses by other tasks.
A process may only modify its own credentials, and so does not need locking to
access or modify its own credentials.
A mutex (cred_replace_mutex) is added to the task_struct to control the effect
of PTRACE_ATTACHED on credential calculations, particularly with respect to
execve().
With this patch, the contents of an active credentials struct may not be
changed directly; rather a new set of credentials must be prepared, modified
and committed using something like the following sequence of events:
struct cred *new = prepare_creds();
int ret = blah(new);
if (ret < 0) {
abort_creds(new);
return ret;
}
return commit_creds(new);
There are some exceptions to this rule: the keyrings pointed to by the active
credentials may be instantiated - keyrings violate the COW rule as managing
COW keyrings is tricky, given that it is possible for a task to directly alter
the keys in a keyring in use by another task.
To help enforce this, various pointers to sets of credentials, such as those in
the task_struct, are declared const. The purpose of this is compile-time
discouragement of altering credentials through those pointers. Once a set of
credentials has been made public through one of these pointers, it may not be
modified, except under special circumstances:
(1) Its reference count may incremented and decremented.
(2) The keyrings to which it points may be modified, but not replaced.
The only safe way to modify anything else is to create a replacement and commit
using the functions described in Documentation/credentials.txt (which will be
added by a later patch).
This patch and the preceding patches have been tested with the LTP SELinux
testsuite.
This patch makes several logical sets of alteration:
(1) execve().
This now prepares and commits credentials in various places in the
security code rather than altering the current creds directly.
(2) Temporary credential overrides.
do_coredump() and sys_faccessat() now prepare their own credentials and
temporarily override the ones currently on the acting thread, whilst
preventing interference from other threads by holding cred_replace_mutex
on the thread being dumped.
This will be replaced in a future patch by something that hands down the
credentials directly to the functions being called, rather than altering
the task's objective credentials.
(3) LSM interface.
A number of functions have been changed, added or removed:
(*) security_capset_check(), ->capset_check()
(*) security_capset_set(), ->capset_set()
Removed in favour of security_capset().
(*) security_capset(), ->capset()
New. This is passed a pointer to the new creds, a pointer to the old
creds and the proposed capability sets. It should fill in the new
creds or return an error. All pointers, barring the pointer to the
new creds, are now const.
(*) security_bprm_apply_creds(), ->bprm_apply_creds()
Changed; now returns a value, which will cause the process to be
killed if it's an error.
(*) security_task_alloc(), ->task_alloc_security()
Removed in favour of security_prepare_creds().
(*) security_cred_free(), ->cred_free()
New. Free security data attached to cred->security.
(*) security_prepare_creds(), ->cred_prepare()
New. Duplicate any security data attached to cred->security.
(*) security_commit_creds(), ->cred_commit()
New. Apply any security effects for the upcoming installation of new
security by commit_creds().
(*) security_task_post_setuid(), ->task_post_setuid()
Removed in favour of security_task_fix_setuid().
(*) security_task_fix_setuid(), ->task_fix_setuid()
Fix up the proposed new credentials for setuid(). This is used by
cap_set_fix_setuid() to implicitly adjust capabilities in line with
setuid() changes. Changes are made to the new credentials, rather
than the task itself as in security_task_post_setuid().
(*) security_task_reparent_to_init(), ->task_reparent_to_init()
Removed. Instead the task being reparented to init is referred
directly to init's credentials.
NOTE! This results in the loss of some state: SELinux's osid no
longer records the sid of the thread that forked it.
(*) security_key_alloc(), ->key_alloc()
(*) security_key_permission(), ->key_permission()
Changed. These now take cred pointers rather than task pointers to
refer to the security context.
(4) sys_capset().
This has been simplified and uses less locking. The LSM functions it
calls have been merged.
(5) reparent_to_kthreadd().
This gives the current thread the same credentials as init by simply using
commit_thread() to point that way.
(6) __sigqueue_alloc() and switch_uid()
__sigqueue_alloc() can't stop the target task from changing its creds
beneath it, so this function gets a reference to the currently applicable
user_struct which it then passes into the sigqueue struct it returns if
successful.
switch_uid() is now called from commit_creds(), and possibly should be
folded into that. commit_creds() should take care of protecting
__sigqueue_alloc().
(7) [sg]et[ug]id() and co and [sg]et_current_groups.
The set functions now all use prepare_creds(), commit_creds() and
abort_creds() to build and check a new set of credentials before applying
it.
security_task_set[ug]id() is called inside the prepared section. This
guarantees that nothing else will affect the creds until we've finished.
The calling of set_dumpable() has been moved into commit_creds().
Much of the functionality of set_user() has been moved into
commit_creds().
The get functions all simply access the data directly.
(8) security_task_prctl() and cap_task_prctl().
security_task_prctl() has been modified to return -ENOSYS if it doesn't
want to handle a function, or otherwise return the return value directly
rather than through an argument.
Additionally, cap_task_prctl() now prepares a new set of credentials, even
if it doesn't end up using it.
(9) Keyrings.
A number of changes have been made to the keyrings code:
(a) switch_uid_keyring(), copy_keys(), exit_keys() and suid_keys() have
all been dropped and built in to the credentials functions directly.
They may want separating out again later.
(b) key_alloc() and search_process_keyrings() now take a cred pointer
rather than a task pointer to specify the security context.
(c) copy_creds() gives a new thread within the same thread group a new
thread keyring if its parent had one, otherwise it discards the thread
keyring.
(d) The authorisation key now points directly to the credentials to extend
the search into rather pointing to the task that carries them.
(e) Installing thread, process or session keyrings causes a new set of
credentials to be created, even though it's not strictly necessary for
process or session keyrings (they're shared).
(10) Usermode helper.
The usermode helper code now carries a cred struct pointer in its
subprocess_info struct instead of a new session keyring pointer. This set
of credentials is derived from init_cred and installed on the new process
after it has been cloned.
call_usermodehelper_setup() allocates the new credentials and
call_usermodehelper_freeinfo() discards them if they haven't been used. A
special cred function (prepare_usermodeinfo_creds()) is provided
specifically for call_usermodehelper_setup() to call.
call_usermodehelper_setkeys() adjusts the credentials to sport the
supplied keyring as the new session keyring.
(11) SELinux.
SELinux has a number of changes, in addition to those to support the LSM
interface changes mentioned above:
(a) selinux_setprocattr() no longer does its check for whether the
current ptracer can access processes with the new SID inside the lock
that covers getting the ptracer's SID. Whilst this lock ensures that
the check is done with the ptracer pinned, the result is only valid
until the lock is released, so there's no point doing it inside the
lock.
(12) is_single_threaded().
This function has been extracted from selinux_setprocattr() and put into
a file of its own in the lib/ directory as join_session_keyring() now
wants to use it too.
The code in SELinux just checked to see whether a task shared mm_structs
with other tasks (CLONE_VM), but that isn't good enough. We really want
to know if they're part of the same thread group (CLONE_THREAD).
(13) nfsd.
The NFS server daemon now has to use the COW credentials to set the
credentials it is going to use. It really needs to pass the credentials
down to the functions it calls, but it can't do that until other patches
in this series have been applied.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: James Morris <jmorris@namei.org>
2008-11-13 16:39:23 -07:00
|
|
|
key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred,
|
|
|
|
perm, flags);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (IS_ERR(key)) {
|
2008-02-07 01:15:26 -07:00
|
|
|
key_ref = ERR_CAST(key);
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error_3;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* instantiate it and link it into the target keyring */
|
2010-04-30 06:32:39 -07:00
|
|
|
ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL,
|
|
|
|
&prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (ret < 0) {
|
|
|
|
key_put(key);
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(ret);
|
|
|
|
goto error_3;
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
error_3:
|
2010-04-30 06:32:39 -07:00
|
|
|
__key_link_end(keyring, ktype, prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
error_2:
|
|
|
|
key_type_put(ktype);
|
|
|
|
error:
|
2005-09-28 09:03:15 -07:00
|
|
|
return key_ref;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
found_matching_key:
|
|
|
|
/* we found a matching key, so we're going to try to update it
|
|
|
|
* - we can drop the locks first as we have the key pinned
|
|
|
|
*/
|
2010-04-30 06:32:39 -07:00
|
|
|
__key_link_end(keyring, ktype, prealloc);
|
2005-04-16 15:20:36 -07:00
|
|
|
key_type_put(ktype);
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = __key_update(key_ref, payload, plen);
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_create_or_update);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_update - Update a key's contents.
|
|
|
|
* @key_ref: The pointer (plus possession flag) to the key.
|
|
|
|
* @payload: The data to be used to update the key.
|
|
|
|
* @plen: The length of @payload.
|
|
|
|
*
|
|
|
|
* Attempt to update the contents of a key with the given payload data. The
|
|
|
|
* caller must be granted Write permission on the key. Negative keys can be
|
|
|
|
* instantiated by this method.
|
|
|
|
*
|
|
|
|
* Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
|
|
|
|
* type does not support updating. The key type may return other errors.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
int key_update(key_ref_t key_ref, const void *payload, size_t plen)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
2005-09-28 09:03:15 -07:00
|
|
|
struct key *key = key_ref_to_ptr(key_ref);
|
2005-04-16 15:20:36 -07:00
|
|
|
int ret;
|
|
|
|
|
|
|
|
key_check(key);
|
|
|
|
|
|
|
|
/* the key must be writable */
|
2005-10-30 16:02:44 -07:00
|
|
|
ret = key_permission(key_ref, KEY_WRITE);
|
|
|
|
if (ret < 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
|
|
|
|
|
|
|
/* attempt to update it if supported */
|
|
|
|
ret = -EOPNOTSUPP;
|
|
|
|
if (key->type->update) {
|
|
|
|
down_write(&key->sem);
|
|
|
|
|
2005-10-30 16:02:44 -07:00
|
|
|
ret = key->type->update(key, payload, plen);
|
2005-06-23 22:00:49 -07:00
|
|
|
if (ret == 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
/* updating a negative key instantiates it */
|
2005-06-23 22:00:49 -07:00
|
|
|
clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
up_write(&key->sem);
|
|
|
|
}
|
|
|
|
|
|
|
|
error:
|
|
|
|
return ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_update);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* key_revoke - Revoke a key.
|
|
|
|
* @key: The key to be revoked.
|
|
|
|
*
|
|
|
|
* Mark a key as being revoked and ask the type to free up its resources. The
|
|
|
|
* revocation timeout is set and the key and all its links will be
|
|
|
|
* automatically garbage collected after key_gc_delay amount of time if they
|
|
|
|
* are not manually dealt with first.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
void key_revoke(struct key *key)
|
|
|
|
{
|
2009-09-02 01:14:00 -07:00
|
|
|
struct timespec now;
|
|
|
|
time_t time;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
key_check(key);
|
|
|
|
|
2007-10-16 23:29:46 -07:00
|
|
|
/* make sure no one's trying to change or use the key when we mark it
|
|
|
|
* - we tell lockdep that we might nest because we might be revoking an
|
|
|
|
* authorisation key whilst holding the sem on a key we've just
|
|
|
|
* instantiated
|
|
|
|
*/
|
|
|
|
down_write_nested(&key->sem, 1);
|
|
|
|
if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
|
|
|
|
key->type->revoke)
|
2006-06-22 14:47:18 -07:00
|
|
|
key->type->revoke(key);
|
|
|
|
|
2009-09-02 01:14:00 -07:00
|
|
|
/* set the death time to no more than the expiry time */
|
|
|
|
now = current_kernel_time();
|
|
|
|
time = now.tv_sec;
|
|
|
|
if (key->revoked_at == 0 || key->revoked_at > time) {
|
|
|
|
key->revoked_at = time;
|
2009-09-14 09:26:13 -07:00
|
|
|
key_schedule_gc(key->revoked_at + key_gc_delay);
|
2009-09-02 01:14:00 -07:00
|
|
|
}
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
up_write(&key->sem);
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(key_revoke);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* register_key_type - Register a type of key.
|
|
|
|
* @ktype: The new key type.
|
|
|
|
*
|
|
|
|
* Register a new key type.
|
|
|
|
*
|
|
|
|
* Returns 0 on success or -EEXIST if a type of this name already exists.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
int register_key_type(struct key_type *ktype)
|
|
|
|
{
|
|
|
|
struct key_type *p;
|
|
|
|
int ret;
|
|
|
|
|
2011-11-16 04:15:54 -07:00
|
|
|
memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
ret = -EEXIST;
|
|
|
|
down_write(&key_types_sem);
|
|
|
|
|
|
|
|
/* disallow key types with the same name */
|
|
|
|
list_for_each_entry(p, &key_types_list, link) {
|
|
|
|
if (strcmp(p->name, ktype->name) == 0)
|
|
|
|
goto out;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* store the type */
|
|
|
|
list_add(&ktype->link, &key_types_list);
|
|
|
|
ret = 0;
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
out:
|
2005-04-16 15:20:36 -07:00
|
|
|
up_write(&key_types_sem);
|
|
|
|
return ret;
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(register_key_type);
|
|
|
|
|
2011-01-20 09:38:33 -07:00
|
|
|
/**
|
|
|
|
* unregister_key_type - Unregister a type of key.
|
|
|
|
* @ktype: The key type.
|
|
|
|
*
|
|
|
|
* Unregister a key type and mark all the extant keys of this type as dead.
|
|
|
|
* Those keys of this type are then destroyed to get rid of their payloads and
|
|
|
|
* they and their links will be garbage collected as soon as possible.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
void unregister_key_type(struct key_type *ktype)
|
|
|
|
{
|
|
|
|
down_write(&key_types_sem);
|
|
|
|
list_del_init(&ktype->link);
|
KEYS: Correctly destroy key payloads when their keytype is removed
unregister_key_type() has code to mark a key as dead and make it unavailable in
one loop and then destroy all those unavailable key payloads in the next loop.
However, the loop to mark keys dead renders the key undetectable to the second
loop by changing the key type pointer also.
Fix this by the following means:
(1) The key code has two garbage collectors: one deletes unreferenced keys and
the other alters keyrings to delete links to old dead, revoked and expired
keys. They can end up holding each other up as both want to scan the key
serial tree under spinlock. Combine these into a single routine.
(2) Move the dead key marking, dead link removal and dead key removal into the
garbage collector as a three phase process running over the three cycles
of the normal garbage collection procedure. This is tracked by the
KEY_GC_REAPING_DEAD_1, _2 and _3 state flags.
unregister_key_type() then just unlinks the key type from the list, wakes
up the garbage collector and waits for the third phase to complete.
(3) Downgrade the key types sem in unregister_key_type() once it has deleted
the key type from the list so that it doesn't block the keyctl() syscall.
(4) Dead keys that cannot be simply removed in the third phase have their
payloads destroyed with the key's semaphore write-locked to prevent
interference by the keyctl() syscall. There should be no in-kernel users
of dead keys of that type by the point of unregistration, though keyctl()
may be holding a reference.
(5) Only perform timer recalculation in the GC if the timer actually expired.
If it didn't, we'll get another cycle when it goes off - and if the key
that actually triggered it has been removed, it's not a problem.
(6) Only garbage collect link if the timer expired or if we're doing dead key
clean up phase 2.
(7) As only key_garbage_collector() is permitted to use rb_erase() on the key
serial tree, it doesn't need to revalidate its cursor after dropping the
spinlock as the node the cursor points to must still exist in the tree.
(8) Drop the spinlock in the GC if there is contention on it or if we need to
reschedule. After dealing with that, get the spinlock again and resume
scanning.
This has been tested in the following ways:
(1) Run the keyutils testsuite against it.
(2) Using the AF_RXRPC and RxKAD modules to test keytype removal:
Load the rxrpc_s key type:
# insmod /tmp/af-rxrpc.ko
# insmod /tmp/rxkad.ko
Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c):
# /tmp/listen &
[1] 8173
Find the key:
# grep rxrpc_s /proc/keys
091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2
Link it to a session keyring, preferably one with a higher serial number:
# keyctl link 0x20e36251 @s
Kill the process (the key should remain as it's linked to another place):
# fg
/tmp/listen
^C
Remove the key type:
rmmod rxkad
rmmod af-rxrpc
This can be made a more effective test by altering the following part of
the patch:
if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) {
/* Make sure everyone revalidates their keys if we marked a
* bunch as being dead and make sure all keyring ex-payloads
* are destroyed.
*/
kdebug("dead sync");
synchronize_rcu();
To call synchronize_rcu() in GC phase 1 instead. That causes that the
keyring's old payload content to hang around longer until it's RCU
destroyed - which usually happens after GC phase 3 is complete. This
allows the destroy_dead_key branch to be tested.
Reported-by: Benjamin Coddington <bcodding@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2011-08-22 06:09:36 -07:00
|
|
|
downgrade_write(&key_types_sem);
|
|
|
|
key_gc_keytype(ktype);
|
|
|
|
up_read(&key_types_sem);
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
EXPORT_SYMBOL(unregister_key_type);
|
|
|
|
|
|
|
|
/*
|
2011-01-20 09:38:33 -07:00
|
|
|
* Initialise the key management state.
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
void __init key_init(void)
|
|
|
|
{
|
|
|
|
/* allocate a slab in which we can store keys */
|
|
|
|
key_jar = kmem_cache_create("key_jar", sizeof(struct key),
|
2007-07-19 18:11:58 -07:00
|
|
|
0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* add the special key types */
|
|
|
|
list_add_tail(&key_type_keyring.link, &key_types_list);
|
|
|
|
list_add_tail(&key_type_dead.link, &key_types_list);
|
|
|
|
list_add_tail(&key_type_user.link, &key_types_list);
|
2012-01-17 14:09:11 -07:00
|
|
|
list_add_tail(&key_type_logon.link, &key_types_list);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* record the root user tracking */
|
|
|
|
rb_link_node(&root_key_user.node,
|
|
|
|
NULL,
|
|
|
|
&key_user_tree.rb_node);
|
|
|
|
|
|
|
|
rb_insert_color(&root_key_user.node,
|
|
|
|
&key_user_tree);
|
2011-01-20 09:38:27 -07:00
|
|
|
}
|