2008-04-29 01:01:31 -07:00
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/* Keyring handling
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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) 2004-2005, 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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#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/seq_file.h>
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#include <linux/err.h>
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2008-11-13 16:39:13 -07:00
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#include <keys/keyring-type.h>
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2005-04-16 15:20:36 -07:00
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#include <asm/uaccess.h>
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#include "internal.h"
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/*
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* when plumbing the depths of the key tree, this sets a hard limit set on how
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* deep we're willing to go
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*/
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#define KEYRING_SEARCH_MAX_DEPTH 6
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/*
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* we keep all named keyrings in a hash to speed looking them up
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*/
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#define KEYRING_NAME_HASH_SIZE (1 << 5)
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static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
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static DEFINE_RWLOCK(keyring_name_lock);
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static inline unsigned keyring_hash(const char *desc)
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{
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unsigned bucket = 0;
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for (; *desc; desc++)
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bucket += (unsigned char) *desc;
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return bucket & (KEYRING_NAME_HASH_SIZE - 1);
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}
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/*
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* the keyring type definition
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*/
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static int keyring_instantiate(struct key *keyring,
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const void *data, size_t datalen);
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static int keyring_match(const struct key *keyring, const void *criterion);
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2006-06-26 00:24:51 -07:00
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static void keyring_revoke(struct key *keyring);
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2005-04-16 15:20:36 -07:00
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static void keyring_destroy(struct key *keyring);
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static void keyring_describe(const struct key *keyring, struct seq_file *m);
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static long keyring_read(const struct key *keyring,
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char __user *buffer, size_t buflen);
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struct key_type key_type_keyring = {
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.name = "keyring",
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.def_datalen = sizeof(struct keyring_list),
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.instantiate = keyring_instantiate,
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.match = keyring_match,
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2006-06-26 00:24:51 -07:00
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.revoke = keyring_revoke,
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2005-04-16 15:20:36 -07:00
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.destroy = keyring_destroy,
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.describe = keyring_describe,
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.read = keyring_read,
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};
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2007-04-26 15:46:23 -07:00
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EXPORT_SYMBOL(key_type_keyring);
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2005-04-16 15:20:36 -07:00
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/*
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* semaphore to serialise link/link calls to prevent two link calls in parallel
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* introducing a cycle
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*/
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2006-01-06 01:11:25 -07:00
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static DECLARE_RWSEM(keyring_serialise_link_sem);
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2005-04-16 15:20:36 -07:00
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/*****************************************************************************/
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/*
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* publish the name of a keyring so that it can be found by name (if it has
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* one)
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*/
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2008-04-29 01:01:31 -07:00
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static void keyring_publish_name(struct key *keyring)
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2005-04-16 15:20:36 -07:00
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{
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int bucket;
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if (keyring->description) {
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bucket = keyring_hash(keyring->description);
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write_lock(&keyring_name_lock);
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if (!keyring_name_hash[bucket].next)
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INIT_LIST_HEAD(&keyring_name_hash[bucket]);
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list_add_tail(&keyring->type_data.link,
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&keyring_name_hash[bucket]);
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write_unlock(&keyring_name_lock);
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}
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} /* end keyring_publish_name() */
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/*****************************************************************************/
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/*
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* initialise a keyring
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* - we object if we were given any data
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*/
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static int keyring_instantiate(struct key *keyring,
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const void *data, size_t datalen)
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{
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int ret;
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ret = -EINVAL;
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if (datalen == 0) {
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/* make the keyring available by name if it has one */
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keyring_publish_name(keyring);
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ret = 0;
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}
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return ret;
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} /* end keyring_instantiate() */
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/*****************************************************************************/
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/*
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* match keyrings on their name
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*/
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static int keyring_match(const struct key *keyring, const void *description)
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{
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return keyring->description &&
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strcmp(keyring->description, description) == 0;
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} /* end keyring_match() */
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/*****************************************************************************/
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/*
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* dispose of the data dangling from the corpse of a keyring
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*/
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static void keyring_destroy(struct key *keyring)
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{
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struct keyring_list *klist;
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int loop;
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if (keyring->description) {
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write_lock(&keyring_name_lock);
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2005-08-04 13:07:07 -07:00
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if (keyring->type_data.link.next != NULL &&
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!list_empty(&keyring->type_data.link))
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list_del(&keyring->type_data.link);
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2005-04-16 15:20:36 -07:00
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write_unlock(&keyring_name_lock);
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}
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2010-02-22 18:04:56 -07:00
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klist = rcu_dereference_check(keyring->payload.subscriptions,
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rcu_read_lock_held() ||
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atomic_read(&keyring->usage) == 0);
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2005-04-16 15:20:36 -07:00
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if (klist) {
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for (loop = klist->nkeys - 1; loop >= 0; loop--)
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key_put(klist->keys[loop]);
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kfree(klist);
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}
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} /* end keyring_destroy() */
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/*****************************************************************************/
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/*
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* describe the keyring
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*/
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static void keyring_describe(const struct key *keyring, struct seq_file *m)
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{
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struct keyring_list *klist;
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if (keyring->description) {
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seq_puts(m, keyring->description);
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}
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else {
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seq_puts(m, "[anon]");
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}
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2005-06-23 22:00:49 -07:00
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rcu_read_lock();
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klist = rcu_dereference(keyring->payload.subscriptions);
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2005-04-16 15:20:36 -07:00
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if (klist)
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seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
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else
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seq_puts(m, ": empty");
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2005-06-23 22:00:49 -07:00
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rcu_read_unlock();
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2005-04-16 15:20:36 -07:00
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} /* end keyring_describe() */
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/*****************************************************************************/
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/*
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* read a list of key IDs from the keyring's contents
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2005-06-23 22:00:49 -07:00
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* - the keyring's semaphore is read-locked
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2005-04-16 15:20:36 -07:00
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*/
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static long keyring_read(const struct key *keyring,
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char __user *buffer, size_t buflen)
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{
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struct keyring_list *klist;
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struct key *key;
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size_t qty, tmp;
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int loop, ret;
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ret = 0;
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2010-04-27 14:05:11 -07:00
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klist = keyring->payload.subscriptions;
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2005-04-16 15:20:36 -07:00
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if (klist) {
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/* calculate how much data we could return */
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qty = klist->nkeys * sizeof(key_serial_t);
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if (buffer && buflen > 0) {
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if (buflen > qty)
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buflen = qty;
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/* copy the IDs of the subscribed keys into the
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* buffer */
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ret = -EFAULT;
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for (loop = 0; loop < klist->nkeys; loop++) {
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key = klist->keys[loop];
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tmp = sizeof(key_serial_t);
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if (tmp > buflen)
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tmp = buflen;
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if (copy_to_user(buffer,
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&key->serial,
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tmp) != 0)
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goto error;
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buflen -= tmp;
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if (buflen == 0)
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break;
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buffer += tmp;
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}
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}
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ret = qty;
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}
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error:
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return ret;
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} /* end keyring_read() */
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/*****************************************************************************/
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/*
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* allocate a keyring and link into the destination keyring
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*/
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struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
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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
|
|
|
const struct cred *cred, unsigned long flags,
|
2006-06-22 14:47:17 -07:00
|
|
|
struct key *dest)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
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|
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struct key *keyring;
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|
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int ret;
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|
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keyring = key_alloc(&key_type_keyring, description,
|
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, gid, cred,
|
2005-10-30 16:02:44 -07:00
|
|
|
(KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
|
2006-06-26 00:24:50 -07:00
|
|
|
flags);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
if (!IS_ERR(keyring)) {
|
[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
|
|
|
ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (ret < 0) {
|
|
|
|
key_put(keyring);
|
|
|
|
keyring = ERR_PTR(ret);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
return keyring;
|
|
|
|
|
|
|
|
} /* end keyring_alloc() */
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* search the supplied keyring tree for a key that matches the criterion
|
|
|
|
* - perform a breadth-then-depth search up to the prescribed limit
|
|
|
|
* - we only find keys on which we have search permission
|
|
|
|
* - we use the supplied match function to see if the description (or other
|
|
|
|
* feature of interest) matches
|
[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
|
|
|
* - we rely on RCU to prevent the keyring lists from disappearing on us
|
2005-04-16 15:20:36 -07:00
|
|
|
* - we return -EAGAIN if we didn't find any matching key
|
|
|
|
* - we return -ENOKEY if we only found negative matching keys
|
2005-09-28 09:03:15 -07:00
|
|
|
* - we propagate the possession attribute from the keyring ref to the key ref
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref_t keyring_search_aux(key_ref_t keyring_ref,
|
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,
|
2005-09-28 09:03:15 -07:00
|
|
|
struct key_type *type,
|
|
|
|
const void *description,
|
|
|
|
key_match_func_t match)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
|
|
|
struct {
|
2005-06-23 22:00:49 -07:00
|
|
|
struct keyring_list *keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
int kix;
|
|
|
|
} stack[KEYRING_SEARCH_MAX_DEPTH];
|
|
|
|
|
|
|
|
struct keyring_list *keylist;
|
|
|
|
struct timespec now;
|
2008-04-29 01:01:22 -07:00
|
|
|
unsigned long possessed, kflags;
|
2005-09-28 09:03:15 -07:00
|
|
|
struct key *keyring, *key;
|
|
|
|
key_ref_t key_ref;
|
2005-04-16 15:20:36 -07:00
|
|
|
long err;
|
2005-06-23 22:00:49 -07:00
|
|
|
int sp, kix;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
keyring = key_ref_to_ptr(keyring_ref);
|
|
|
|
possessed = is_key_possessed(keyring_ref);
|
2005-04-16 15:20:36 -07:00
|
|
|
key_check(keyring);
|
|
|
|
|
|
|
|
/* top keyring must have search permission to begin the search */
|
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
|
|
|
err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
|
2005-10-30 16:02:44 -07:00
|
|
|
if (err < 0) {
|
|
|
|
key_ref = ERR_PTR(err);
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
2005-10-30 16:02:44 -07:00
|
|
|
}
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(-ENOTDIR);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (keyring->type != &key_type_keyring)
|
|
|
|
goto error;
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
rcu_read_lock();
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
now = current_kernel_time();
|
|
|
|
err = -EAGAIN;
|
|
|
|
sp = 0;
|
|
|
|
|
2008-04-29 01:01:22 -07:00
|
|
|
/* firstly we should check to see if this top-level keyring is what we
|
|
|
|
* are looking for */
|
|
|
|
key_ref = ERR_PTR(-EAGAIN);
|
|
|
|
kflags = keyring->flags;
|
|
|
|
if (keyring->type == type && match(keyring, description)) {
|
|
|
|
key = keyring;
|
|
|
|
|
|
|
|
/* check it isn't negative and hasn't expired or been
|
|
|
|
* revoked */
|
|
|
|
if (kflags & (1 << KEY_FLAG_REVOKED))
|
|
|
|
goto error_2;
|
|
|
|
if (key->expiry && now.tv_sec >= key->expiry)
|
|
|
|
goto error_2;
|
|
|
|
key_ref = ERR_PTR(-ENOKEY);
|
|
|
|
if (kflags & (1 << KEY_FLAG_NEGATIVE))
|
|
|
|
goto error_2;
|
|
|
|
goto found;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* otherwise, the top keyring must not be revoked, expired, or
|
|
|
|
* negatively instantiated if we are to search it */
|
|
|
|
key_ref = ERR_PTR(-EAGAIN);
|
|
|
|
if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
|
|
|
|
(keyring->expiry && now.tv_sec >= keyring->expiry))
|
|
|
|
goto error_2;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/* start processing a new keyring */
|
2005-09-28 09:03:15 -07:00
|
|
|
descend:
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
goto not_this_keyring;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
keylist = rcu_dereference(keyring->payload.subscriptions);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!keylist)
|
|
|
|
goto not_this_keyring;
|
|
|
|
|
|
|
|
/* iterate through the keys in this keyring first */
|
|
|
|
for (kix = 0; kix < keylist->nkeys; kix++) {
|
|
|
|
key = keylist->keys[kix];
|
2008-04-29 01:01:22 -07:00
|
|
|
kflags = key->flags;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* ignore keys not of this type */
|
|
|
|
if (key->type != type)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
/* skip revoked keys and expired keys */
|
2008-04-29 01:01:22 -07:00
|
|
|
if (kflags & (1 << KEY_FLAG_REVOKED))
|
2005-04-16 15:20:36 -07:00
|
|
|
continue;
|
|
|
|
|
|
|
|
if (key->expiry && now.tv_sec >= key->expiry)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
/* keys that don't match */
|
|
|
|
if (!match(key, description))
|
|
|
|
continue;
|
|
|
|
|
|
|
|
/* key must have search permissions */
|
2005-10-30 16:02:44 -07:00
|
|
|
if (key_task_permission(make_key_ref(key, possessed),
|
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
|
|
|
cred, KEY_SEARCH) < 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
continue;
|
|
|
|
|
2008-04-29 01:01:22 -07:00
|
|
|
/* we set a different error code if we pass a negative key */
|
|
|
|
if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
|
2005-04-16 15:20:36 -07:00
|
|
|
err = -ENOKEY;
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
|
|
|
goto found;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* search through the keyrings nested in this one */
|
|
|
|
kix = 0;
|
2005-09-28 09:03:15 -07:00
|
|
|
ascend:
|
2005-06-23 22:00:49 -07:00
|
|
|
for (; kix < keylist->nkeys; kix++) {
|
2005-04-16 15:20:36 -07:00
|
|
|
key = keylist->keys[kix];
|
|
|
|
if (key->type != &key_type_keyring)
|
2005-06-23 22:00:49 -07:00
|
|
|
continue;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* recursively search nested keyrings
|
|
|
|
* - only search keyrings for which we have search permission
|
|
|
|
*/
|
|
|
|
if (sp >= KEYRING_SEARCH_MAX_DEPTH)
|
2005-06-23 22:00:49 -07:00
|
|
|
continue;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-11-07 01:59:30 -07:00
|
|
|
if (key_task_permission(make_key_ref(key, possessed),
|
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
|
|
|
cred, KEY_SEARCH) < 0)
|
2005-06-23 22:00:49 -07:00
|
|
|
continue;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* stack the current position */
|
2005-06-23 22:00:49 -07:00
|
|
|
stack[sp].keylist = keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
stack[sp].kix = kix;
|
|
|
|
sp++;
|
|
|
|
|
|
|
|
/* begin again with the new keyring */
|
|
|
|
keyring = key;
|
|
|
|
goto descend;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* the keyring we're looking at was disqualified or didn't contain a
|
|
|
|
* matching key */
|
2005-09-28 09:03:15 -07:00
|
|
|
not_this_keyring:
|
2005-04-16 15:20:36 -07:00
|
|
|
if (sp > 0) {
|
|
|
|
/* resume the processing of a keyring higher up in the tree */
|
|
|
|
sp--;
|
2005-06-23 22:00:49 -07:00
|
|
|
keylist = stack[sp].keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
kix = stack[sp].kix + 1;
|
|
|
|
goto ascend;
|
|
|
|
}
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = ERR_PTR(err);
|
|
|
|
goto error_2;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* we found a viable match */
|
2005-09-28 09:03:15 -07:00
|
|
|
found:
|
2005-04-16 15:20:36 -07:00
|
|
|
atomic_inc(&key->usage);
|
|
|
|
key_check(key);
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref = make_key_ref(key, possessed);
|
|
|
|
error_2:
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_read_unlock();
|
2005-09-28 09:03:15 -07:00
|
|
|
error:
|
|
|
|
return key_ref;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
} /* end keyring_search_aux() */
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* search the supplied keyring tree for a key that matches the criterion
|
|
|
|
* - perform a breadth-then-depth search up to the prescribed limit
|
|
|
|
* - we only find keys on which we have search permission
|
|
|
|
* - we readlock the keyrings as we search down the tree
|
|
|
|
* - we return -EAGAIN if we didn't find any matching key
|
|
|
|
* - we return -ENOKEY if we only found negative matching keys
|
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref_t keyring_search(key_ref_t keyring,
|
|
|
|
struct key_type *type,
|
|
|
|
const char *description)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
[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
|
|
|
if (!type->match)
|
|
|
|
return ERR_PTR(-ENOKEY);
|
|
|
|
|
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
|
|
|
return keyring_search_aux(keyring, current->cred,
|
[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
|
|
|
type, description, type->match);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
} /* end keyring_search() */
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(keyring_search);
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* search the given keyring only (no recursion)
|
|
|
|
* - keyring must be locked by caller
|
2006-04-10 07:15:21 -07:00
|
|
|
* - caller must guarantee that the keyring is a keyring
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2005-09-28 09:03:15 -07:00
|
|
|
key_ref_t __keyring_search_one(key_ref_t keyring_ref,
|
|
|
|
const struct key_type *ktype,
|
|
|
|
const char *description,
|
|
|
|
key_perm_t perm)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
|
|
|
struct keyring_list *klist;
|
2005-09-28 09:03:15 -07:00
|
|
|
unsigned long possessed;
|
|
|
|
struct key *keyring, *key;
|
2005-04-16 15:20:36 -07:00
|
|
|
int loop;
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
keyring = key_ref_to_ptr(keyring_ref);
|
|
|
|
possessed = is_key_possessed(keyring_ref);
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_read_lock();
|
|
|
|
|
|
|
|
klist = rcu_dereference(keyring->payload.subscriptions);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (klist) {
|
|
|
|
for (loop = 0; loop < klist->nkeys; loop++) {
|
|
|
|
key = klist->keys[loop];
|
|
|
|
|
|
|
|
if (key->type == ktype &&
|
[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
|
|
|
(!key->type->match ||
|
|
|
|
key->type->match(key, description)) &&
|
2005-09-28 09:03:15 -07:00
|
|
|
key_permission(make_key_ref(key, possessed),
|
2005-12-01 01:51:18 -07:00
|
|
|
perm) == 0 &&
|
2005-06-23 22:00:49 -07:00
|
|
|
!test_bit(KEY_FLAG_REVOKED, &key->flags)
|
2005-04-16 15:20:36 -07:00
|
|
|
)
|
|
|
|
goto found;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2005-09-28 09:03:15 -07:00
|
|
|
rcu_read_unlock();
|
|
|
|
return ERR_PTR(-ENOKEY);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
found:
|
|
|
|
atomic_inc(&key->usage);
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_read_unlock();
|
2005-09-28 09:03:15 -07:00
|
|
|
return make_key_ref(key, possessed);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
} /* end __keyring_search_one() */
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* find a keyring with the specified name
|
|
|
|
* - all named keyrings are searched
|
2008-04-29 01:01:31 -07:00
|
|
|
* - normally only finds keyrings with search permission for the current process
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
2008-04-29 01:01:31 -07:00
|
|
|
struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
|
2005-04-16 15:20:36 -07:00
|
|
|
{
|
|
|
|
struct key *keyring;
|
|
|
|
int bucket;
|
|
|
|
|
|
|
|
if (!name)
|
KEYS: find_keyring_by_name() can gain access to a freed keyring
find_keyring_by_name() can gain access to a keyring that has had its reference
count reduced to zero, and is thus ready to be freed. This then allows the
dead keyring to be brought back into use whilst it is being destroyed.
The following timeline illustrates the process:
|(cleaner) (user)
|
| free_user(user) sys_keyctl()
| | |
| key_put(user->session_keyring) keyctl_get_keyring_ID()
| || //=> keyring->usage = 0 |
| |schedule_work(&key_cleanup_task) lookup_user_key()
| || |
| kmem_cache_free(,user) |
| . |[KEY_SPEC_USER_KEYRING]
| . install_user_keyrings()
| . ||
| key_cleanup() [<= worker_thread()] ||
| | ||
| [spin_lock(&key_serial_lock)] |[mutex_lock(&key_user_keyr..mutex)]
| | ||
| atomic_read() == 0 ||
| |{ rb_ease(&key->serial_node,) } ||
| | ||
| [spin_unlock(&key_serial_lock)] |find_keyring_by_name()
| | |||
| keyring_destroy(keyring) ||[read_lock(&keyring_name_lock)]
| || |||
| |[write_lock(&keyring_name_lock)] ||atomic_inc(&keyring->usage)
| |. ||| *** GET freeing keyring ***
| |. ||[read_unlock(&keyring_name_lock)]
| || ||
| |list_del() |[mutex_unlock(&key_user_k..mutex)]
| || |
| |[write_unlock(&keyring_name_lock)] ** INVALID keyring is returned **
| | .
| kmem_cache_free(,keyring) .
| .
| atomic_dec(&keyring->usage)
v *** DESTROYED ***
TIME
If CONFIG_SLUB_DEBUG=y then we may see the following message generated:
=============================================================================
BUG key_jar: Poison overwritten
-----------------------------------------------------------------------------
INFO: 0xffff880197a7e200-0xffff880197a7e200. First byte 0x6a instead of 0x6b
INFO: Allocated in key_alloc+0x10b/0x35f age=25 cpu=1 pid=5086
INFO: Freed in key_cleanup+0xd0/0xd5 age=12 cpu=1 pid=10
INFO: Slab 0xffffea000592cb90 objects=16 used=2 fp=0xffff880197a7e200 flags=0x200000000000c3
INFO: Object 0xffff880197a7e200 @offset=512 fp=0xffff880197a7e300
Bytes b4 0xffff880197a7e1f0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
Object 0xffff880197a7e200: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b jkkkkkkkkkkkkkkk
Alternatively, we may see a system panic happen, such as:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
IP: [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
PGD 6b2b4067 PUD 6a80d067 PMD 0
Oops: 0000 [#1] SMP
last sysfs file: /sys/kernel/kexec_crash_loaded
CPU 1
...
Pid: 31245, comm: su Not tainted 2.6.34-rc5-nofixed-nodebug #2 D2089/PRIMERGY
RIP: 0010:[<ffffffff810e61a3>] [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
RSP: 0018:ffff88006af3bd98 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88007d19900b
RDX: 0000000100000000 RSI: 00000000000080d0 RDI: ffffffff81828430
RBP: ffffffff81828430 R08: ffff88000a293750 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000100000 R12: 00000000000080d0
R13: 00000000000080d0 R14: 0000000000000296 R15: ffffffff810f20ce
FS: 00007f97116bc700(0000) GS:ffff88000a280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000001 CR3: 000000006a91c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process su (pid: 31245, threadinfo ffff88006af3a000, task ffff8800374414c0)
Stack:
0000000512e0958e 0000000000008000 ffff880037f8d180 0000000000000001
0000000000000000 0000000000008001 ffff88007d199000 ffffffff810f20ce
0000000000008000 ffff88006af3be48 0000000000000024 ffffffff810face3
Call Trace:
[<ffffffff810f20ce>] ? get_empty_filp+0x70/0x12f
[<ffffffff810face3>] ? do_filp_open+0x145/0x590
[<ffffffff810ce208>] ? tlb_finish_mmu+0x2a/0x33
[<ffffffff810ce43c>] ? unmap_region+0xd3/0xe2
[<ffffffff810e4393>] ? virt_to_head_page+0x9/0x2d
[<ffffffff81103916>] ? alloc_fd+0x69/0x10e
[<ffffffff810ef4ed>] ? do_sys_open+0x56/0xfc
[<ffffffff81008a02>] ? system_call_fastpath+0x16/0x1b
Code: 0f 1f 44 00 00 49 89 c6 fa 66 0f 1f 44 00 00 65 4c 8b 04 25 60 e8 00 00 48 8b 45 00 49 01 c0 49 8b 18 48 85 db 74 0d 48 63 45 18 <48> 8b 04 03 49 89 00 eb 14 4c 89 f9 83 ca ff 44 89 e6 48 89 ef
RIP [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
This problem is that find_keyring_by_name does not confirm that the keyring is
valid before accepting it.
Skipping keyrings that have been reduced to a zero count seems the way to go.
To this end, use atomic_inc_not_zero() to increment the usage count and skip
the candidate keyring if that returns false.
The following script _may_ cause the bug to happen, but there's no guarantee
as the window of opportunity is small:
#!/bin/sh
LOOP=100000
USER=dummy_user
/bin/su -c "exit;" $USER || { /usr/sbin/adduser -m $USER; add=1; }
for ((i=0; i<LOOP; i++))
do
/bin/su -c "echo '$i' > /dev/null" $USER
done
(( add == 1 )) && /usr/sbin/userdel -r $USER
exit
Note that the nominated user must not be in use.
An alternative way of testing this may be:
for ((i=0; i<100000; i++))
do
keyctl session foo /bin/true || break
done >&/dev/null
as that uses a keyring named "foo" rather than relying on the user and
user-session named keyrings.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-04-30 06:32:13 -07:00
|
|
|
return ERR_PTR(-EINVAL);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
bucket = keyring_hash(name);
|
|
|
|
|
|
|
|
read_lock(&keyring_name_lock);
|
|
|
|
|
|
|
|
if (keyring_name_hash[bucket].next) {
|
|
|
|
/* search this hash bucket for a keyring with a matching name
|
|
|
|
* that's readable and that hasn't been revoked */
|
|
|
|
list_for_each_entry(keyring,
|
|
|
|
&keyring_name_hash[bucket],
|
|
|
|
type_data.link
|
|
|
|
) {
|
2009-02-26 17:27:55 -07:00
|
|
|
if (keyring->user->user_ns != current_user_ns())
|
|
|
|
continue;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
continue;
|
|
|
|
|
|
|
|
if (strcmp(keyring->description, name) != 0)
|
|
|
|
continue;
|
|
|
|
|
2008-04-29 01:01:31 -07:00
|
|
|
if (!skip_perm_check &&
|
|
|
|
key_permission(make_key_ref(keyring, 0),
|
2005-11-07 01:59:30 -07:00
|
|
|
KEY_SEARCH) < 0)
|
2005-04-16 15:20:36 -07:00
|
|
|
continue;
|
|
|
|
|
KEYS: find_keyring_by_name() can gain access to a freed keyring
find_keyring_by_name() can gain access to a keyring that has had its reference
count reduced to zero, and is thus ready to be freed. This then allows the
dead keyring to be brought back into use whilst it is being destroyed.
The following timeline illustrates the process:
|(cleaner) (user)
|
| free_user(user) sys_keyctl()
| | |
| key_put(user->session_keyring) keyctl_get_keyring_ID()
| || //=> keyring->usage = 0 |
| |schedule_work(&key_cleanup_task) lookup_user_key()
| || |
| kmem_cache_free(,user) |
| . |[KEY_SPEC_USER_KEYRING]
| . install_user_keyrings()
| . ||
| key_cleanup() [<= worker_thread()] ||
| | ||
| [spin_lock(&key_serial_lock)] |[mutex_lock(&key_user_keyr..mutex)]
| | ||
| atomic_read() == 0 ||
| |{ rb_ease(&key->serial_node,) } ||
| | ||
| [spin_unlock(&key_serial_lock)] |find_keyring_by_name()
| | |||
| keyring_destroy(keyring) ||[read_lock(&keyring_name_lock)]
| || |||
| |[write_lock(&keyring_name_lock)] ||atomic_inc(&keyring->usage)
| |. ||| *** GET freeing keyring ***
| |. ||[read_unlock(&keyring_name_lock)]
| || ||
| |list_del() |[mutex_unlock(&key_user_k..mutex)]
| || |
| |[write_unlock(&keyring_name_lock)] ** INVALID keyring is returned **
| | .
| kmem_cache_free(,keyring) .
| .
| atomic_dec(&keyring->usage)
v *** DESTROYED ***
TIME
If CONFIG_SLUB_DEBUG=y then we may see the following message generated:
=============================================================================
BUG key_jar: Poison overwritten
-----------------------------------------------------------------------------
INFO: 0xffff880197a7e200-0xffff880197a7e200. First byte 0x6a instead of 0x6b
INFO: Allocated in key_alloc+0x10b/0x35f age=25 cpu=1 pid=5086
INFO: Freed in key_cleanup+0xd0/0xd5 age=12 cpu=1 pid=10
INFO: Slab 0xffffea000592cb90 objects=16 used=2 fp=0xffff880197a7e200 flags=0x200000000000c3
INFO: Object 0xffff880197a7e200 @offset=512 fp=0xffff880197a7e300
Bytes b4 0xffff880197a7e1f0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
Object 0xffff880197a7e200: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b jkkkkkkkkkkkkkkk
Alternatively, we may see a system panic happen, such as:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
IP: [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
PGD 6b2b4067 PUD 6a80d067 PMD 0
Oops: 0000 [#1] SMP
last sysfs file: /sys/kernel/kexec_crash_loaded
CPU 1
...
Pid: 31245, comm: su Not tainted 2.6.34-rc5-nofixed-nodebug #2 D2089/PRIMERGY
RIP: 0010:[<ffffffff810e61a3>] [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
RSP: 0018:ffff88006af3bd98 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88007d19900b
RDX: 0000000100000000 RSI: 00000000000080d0 RDI: ffffffff81828430
RBP: ffffffff81828430 R08: ffff88000a293750 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000100000 R12: 00000000000080d0
R13: 00000000000080d0 R14: 0000000000000296 R15: ffffffff810f20ce
FS: 00007f97116bc700(0000) GS:ffff88000a280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000001 CR3: 000000006a91c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process su (pid: 31245, threadinfo ffff88006af3a000, task ffff8800374414c0)
Stack:
0000000512e0958e 0000000000008000 ffff880037f8d180 0000000000000001
0000000000000000 0000000000008001 ffff88007d199000 ffffffff810f20ce
0000000000008000 ffff88006af3be48 0000000000000024 ffffffff810face3
Call Trace:
[<ffffffff810f20ce>] ? get_empty_filp+0x70/0x12f
[<ffffffff810face3>] ? do_filp_open+0x145/0x590
[<ffffffff810ce208>] ? tlb_finish_mmu+0x2a/0x33
[<ffffffff810ce43c>] ? unmap_region+0xd3/0xe2
[<ffffffff810e4393>] ? virt_to_head_page+0x9/0x2d
[<ffffffff81103916>] ? alloc_fd+0x69/0x10e
[<ffffffff810ef4ed>] ? do_sys_open+0x56/0xfc
[<ffffffff81008a02>] ? system_call_fastpath+0x16/0x1b
Code: 0f 1f 44 00 00 49 89 c6 fa 66 0f 1f 44 00 00 65 4c 8b 04 25 60 e8 00 00 48 8b 45 00 49 01 c0 49 8b 18 48 85 db 74 0d 48 63 45 18 <48> 8b 04 03 49 89 00 eb 14 4c 89 f9 83 ca ff 44 89 e6 48 89 ef
RIP [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
This problem is that find_keyring_by_name does not confirm that the keyring is
valid before accepting it.
Skipping keyrings that have been reduced to a zero count seems the way to go.
To this end, use atomic_inc_not_zero() to increment the usage count and skip
the candidate keyring if that returns false.
The following script _may_ cause the bug to happen, but there's no guarantee
as the window of opportunity is small:
#!/bin/sh
LOOP=100000
USER=dummy_user
/bin/su -c "exit;" $USER || { /usr/sbin/adduser -m $USER; add=1; }
for ((i=0; i<LOOP; i++))
do
/bin/su -c "echo '$i' > /dev/null" $USER
done
(( add == 1 )) && /usr/sbin/userdel -r $USER
exit
Note that the nominated user must not be in use.
An alternative way of testing this may be:
for ((i=0; i<100000; i++))
do
keyctl session foo /bin/true || break
done >&/dev/null
as that uses a keyring named "foo" rather than relying on the user and
user-session named keyrings.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-04-30 06:32:13 -07:00
|
|
|
/* we've got a match but we might end up racing with
|
|
|
|
* key_cleanup() if the keyring is currently 'dead'
|
|
|
|
* (ie. it has a zero usage count) */
|
|
|
|
if (!atomic_inc_not_zero(&keyring->usage))
|
|
|
|
continue;
|
|
|
|
goto out;
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
keyring = ERR_PTR(-ENOKEY);
|
KEYS: find_keyring_by_name() can gain access to a freed keyring
find_keyring_by_name() can gain access to a keyring that has had its reference
count reduced to zero, and is thus ready to be freed. This then allows the
dead keyring to be brought back into use whilst it is being destroyed.
The following timeline illustrates the process:
|(cleaner) (user)
|
| free_user(user) sys_keyctl()
| | |
| key_put(user->session_keyring) keyctl_get_keyring_ID()
| || //=> keyring->usage = 0 |
| |schedule_work(&key_cleanup_task) lookup_user_key()
| || |
| kmem_cache_free(,user) |
| . |[KEY_SPEC_USER_KEYRING]
| . install_user_keyrings()
| . ||
| key_cleanup() [<= worker_thread()] ||
| | ||
| [spin_lock(&key_serial_lock)] |[mutex_lock(&key_user_keyr..mutex)]
| | ||
| atomic_read() == 0 ||
| |{ rb_ease(&key->serial_node,) } ||
| | ||
| [spin_unlock(&key_serial_lock)] |find_keyring_by_name()
| | |||
| keyring_destroy(keyring) ||[read_lock(&keyring_name_lock)]
| || |||
| |[write_lock(&keyring_name_lock)] ||atomic_inc(&keyring->usage)
| |. ||| *** GET freeing keyring ***
| |. ||[read_unlock(&keyring_name_lock)]
| || ||
| |list_del() |[mutex_unlock(&key_user_k..mutex)]
| || |
| |[write_unlock(&keyring_name_lock)] ** INVALID keyring is returned **
| | .
| kmem_cache_free(,keyring) .
| .
| atomic_dec(&keyring->usage)
v *** DESTROYED ***
TIME
If CONFIG_SLUB_DEBUG=y then we may see the following message generated:
=============================================================================
BUG key_jar: Poison overwritten
-----------------------------------------------------------------------------
INFO: 0xffff880197a7e200-0xffff880197a7e200. First byte 0x6a instead of 0x6b
INFO: Allocated in key_alloc+0x10b/0x35f age=25 cpu=1 pid=5086
INFO: Freed in key_cleanup+0xd0/0xd5 age=12 cpu=1 pid=10
INFO: Slab 0xffffea000592cb90 objects=16 used=2 fp=0xffff880197a7e200 flags=0x200000000000c3
INFO: Object 0xffff880197a7e200 @offset=512 fp=0xffff880197a7e300
Bytes b4 0xffff880197a7e1f0: 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZZZZZZZZZ
Object 0xffff880197a7e200: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b jkkkkkkkkkkkkkkk
Alternatively, we may see a system panic happen, such as:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
IP: [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
PGD 6b2b4067 PUD 6a80d067 PMD 0
Oops: 0000 [#1] SMP
last sysfs file: /sys/kernel/kexec_crash_loaded
CPU 1
...
Pid: 31245, comm: su Not tainted 2.6.34-rc5-nofixed-nodebug #2 D2089/PRIMERGY
RIP: 0010:[<ffffffff810e61a3>] [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
RSP: 0018:ffff88006af3bd98 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffff88007d19900b
RDX: 0000000100000000 RSI: 00000000000080d0 RDI: ffffffff81828430
RBP: ffffffff81828430 R08: ffff88000a293750 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000100000 R12: 00000000000080d0
R13: 00000000000080d0 R14: 0000000000000296 R15: ffffffff810f20ce
FS: 00007f97116bc700(0000) GS:ffff88000a280000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000001 CR3: 000000006a91c000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process su (pid: 31245, threadinfo ffff88006af3a000, task ffff8800374414c0)
Stack:
0000000512e0958e 0000000000008000 ffff880037f8d180 0000000000000001
0000000000000000 0000000000008001 ffff88007d199000 ffffffff810f20ce
0000000000008000 ffff88006af3be48 0000000000000024 ffffffff810face3
Call Trace:
[<ffffffff810f20ce>] ? get_empty_filp+0x70/0x12f
[<ffffffff810face3>] ? do_filp_open+0x145/0x590
[<ffffffff810ce208>] ? tlb_finish_mmu+0x2a/0x33
[<ffffffff810ce43c>] ? unmap_region+0xd3/0xe2
[<ffffffff810e4393>] ? virt_to_head_page+0x9/0x2d
[<ffffffff81103916>] ? alloc_fd+0x69/0x10e
[<ffffffff810ef4ed>] ? do_sys_open+0x56/0xfc
[<ffffffff81008a02>] ? system_call_fastpath+0x16/0x1b
Code: 0f 1f 44 00 00 49 89 c6 fa 66 0f 1f 44 00 00 65 4c 8b 04 25 60 e8 00 00 48 8b 45 00 49 01 c0 49 8b 18 48 85 db 74 0d 48 63 45 18 <48> 8b 04 03 49 89 00 eb 14 4c 89 f9 83 ca ff 44 89 e6 48 89 ef
RIP [<ffffffff810e61a3>] kmem_cache_alloc+0x5b/0xe9
This problem is that find_keyring_by_name does not confirm that the keyring is
valid before accepting it.
Skipping keyrings that have been reduced to a zero count seems the way to go.
To this end, use atomic_inc_not_zero() to increment the usage count and skip
the candidate keyring if that returns false.
The following script _may_ cause the bug to happen, but there's no guarantee
as the window of opportunity is small:
#!/bin/sh
LOOP=100000
USER=dummy_user
/bin/su -c "exit;" $USER || { /usr/sbin/adduser -m $USER; add=1; }
for ((i=0; i<LOOP; i++))
do
/bin/su -c "echo '$i' > /dev/null" $USER
done
(( add == 1 )) && /usr/sbin/userdel -r $USER
exit
Note that the nominated user must not be in use.
An alternative way of testing this may be:
for ((i=0; i<100000; i++))
do
keyctl session foo /bin/true || break
done >&/dev/null
as that uses a keyring named "foo" rather than relying on the user and
user-session named keyrings.
Reported-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2010-04-30 06:32:13 -07:00
|
|
|
out:
|
|
|
|
read_unlock(&keyring_name_lock);
|
2005-04-16 15:20:36 -07:00
|
|
|
return keyring;
|
|
|
|
|
|
|
|
} /* end find_keyring_by_name() */
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* see if a cycle will will be created by inserting acyclic tree B in acyclic
|
|
|
|
* tree A at the topmost level (ie: as a direct child of A)
|
|
|
|
* - since we are adding B to A at the top level, checking for cycles should
|
|
|
|
* just be a matter of seeing if node A is somewhere in tree B
|
|
|
|
*/
|
|
|
|
static int keyring_detect_cycle(struct key *A, struct key *B)
|
|
|
|
{
|
|
|
|
struct {
|
2005-06-23 22:00:49 -07:00
|
|
|
struct keyring_list *keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
int kix;
|
|
|
|
} stack[KEYRING_SEARCH_MAX_DEPTH];
|
|
|
|
|
|
|
|
struct keyring_list *keylist;
|
|
|
|
struct key *subtree, *key;
|
|
|
|
int sp, kix, ret;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_read_lock();
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
ret = -EDEADLK;
|
|
|
|
if (A == B)
|
2005-06-23 22:00:49 -07:00
|
|
|
goto cycle_detected;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
subtree = B;
|
|
|
|
sp = 0;
|
|
|
|
|
|
|
|
/* start processing a new keyring */
|
|
|
|
descend:
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
goto not_this_keyring;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
keylist = rcu_dereference(subtree->payload.subscriptions);
|
2005-04-16 15:20:36 -07:00
|
|
|
if (!keylist)
|
|
|
|
goto not_this_keyring;
|
|
|
|
kix = 0;
|
|
|
|
|
|
|
|
ascend:
|
|
|
|
/* iterate through the remaining keys in this keyring */
|
|
|
|
for (; kix < keylist->nkeys; kix++) {
|
|
|
|
key = keylist->keys[kix];
|
|
|
|
|
|
|
|
if (key == A)
|
|
|
|
goto cycle_detected;
|
|
|
|
|
|
|
|
/* recursively check nested keyrings */
|
|
|
|
if (key->type == &key_type_keyring) {
|
|
|
|
if (sp >= KEYRING_SEARCH_MAX_DEPTH)
|
|
|
|
goto too_deep;
|
|
|
|
|
|
|
|
/* stack the current position */
|
2005-06-23 22:00:49 -07:00
|
|
|
stack[sp].keylist = keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
stack[sp].kix = kix;
|
|
|
|
sp++;
|
|
|
|
|
|
|
|
/* begin again with the new keyring */
|
|
|
|
subtree = key;
|
|
|
|
goto descend;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/* the keyring we're looking at was disqualified or didn't contain a
|
|
|
|
* matching key */
|
|
|
|
not_this_keyring:
|
|
|
|
if (sp > 0) {
|
|
|
|
/* resume the checking of a keyring higher up in the tree */
|
|
|
|
sp--;
|
2005-06-23 22:00:49 -07:00
|
|
|
keylist = stack[sp].keylist;
|
2005-04-16 15:20:36 -07:00
|
|
|
kix = stack[sp].kix + 1;
|
|
|
|
goto ascend;
|
|
|
|
}
|
|
|
|
|
|
|
|
ret = 0; /* no cycles detected */
|
|
|
|
|
|
|
|
error:
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_read_unlock();
|
2005-04-16 15:20:36 -07:00
|
|
|
return ret;
|
|
|
|
|
|
|
|
too_deep:
|
|
|
|
ret = -ELOOP;
|
2005-06-23 22:00:49 -07:00
|
|
|
goto error;
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
cycle_detected:
|
|
|
|
ret = -EDEADLK;
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
} /* end keyring_detect_cycle() */
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* dispose of a keyring list after the RCU grace period
|
|
|
|
*/
|
|
|
|
static void keyring_link_rcu_disposal(struct rcu_head *rcu)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist =
|
|
|
|
container_of(rcu, struct keyring_list, rcu);
|
|
|
|
|
|
|
|
kfree(klist);
|
|
|
|
|
|
|
|
} /* end keyring_link_rcu_disposal() */
|
|
|
|
|
2006-01-08 02:02:45 -07:00
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* dispose of a keyring list after the RCU grace period, freeing the unlinked
|
|
|
|
* key
|
|
|
|
*/
|
|
|
|
static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist =
|
|
|
|
container_of(rcu, struct keyring_list, rcu);
|
|
|
|
|
|
|
|
key_put(klist->keys[klist->delkey]);
|
|
|
|
kfree(klist);
|
|
|
|
|
|
|
|
} /* end keyring_unlink_rcu_disposal() */
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* link a key into to a keyring
|
2005-06-23 22:00:49 -07:00
|
|
|
* - must be called with the keyring's semaphore write-locked
|
2006-01-08 02:02:45 -07:00
|
|
|
* - discard already extant link to matching key if there is one
|
2005-04-16 15:20:36 -07:00
|
|
|
*/
|
|
|
|
int __key_link(struct key *keyring, struct key *key)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist, *nklist;
|
|
|
|
unsigned max;
|
|
|
|
size_t size;
|
2006-01-08 02:02:45 -07:00
|
|
|
int loop, ret;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
ret = -EKEYREVOKED;
|
2005-06-23 22:00:49 -07:00
|
|
|
if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
|
2005-04-16 15:20:36 -07:00
|
|
|
goto error;
|
|
|
|
|
|
|
|
ret = -ENOTDIR;
|
|
|
|
if (keyring->type != &key_type_keyring)
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
/* serialise link/link calls to prevent parallel calls causing a
|
|
|
|
* cycle when applied to two keyring in opposite orders */
|
|
|
|
down_write(&keyring_serialise_link_sem);
|
|
|
|
|
|
|
|
/* check that we aren't going to create a cycle adding one keyring to
|
|
|
|
* another */
|
|
|
|
if (key->type == &key_type_keyring) {
|
|
|
|
ret = keyring_detect_cycle(keyring, key);
|
|
|
|
if (ret < 0)
|
|
|
|
goto error2;
|
|
|
|
}
|
|
|
|
|
2006-01-08 02:02:45 -07:00
|
|
|
/* see if there's a matching key we can displace */
|
|
|
|
klist = keyring->payload.subscriptions;
|
|
|
|
|
|
|
|
if (klist && klist->nkeys > 0) {
|
|
|
|
struct key_type *type = key->type;
|
|
|
|
|
|
|
|
for (loop = klist->nkeys - 1; loop >= 0; loop--) {
|
|
|
|
if (klist->keys[loop]->type == type &&
|
|
|
|
strcmp(klist->keys[loop]->description,
|
|
|
|
key->description) == 0
|
|
|
|
) {
|
|
|
|
/* found a match - replace with new key */
|
|
|
|
size = sizeof(struct key *) * klist->maxkeys;
|
|
|
|
size += sizeof(*klist);
|
|
|
|
BUG_ON(size > PAGE_SIZE);
|
|
|
|
|
|
|
|
ret = -ENOMEM;
|
2006-12-06 21:33:47 -07:00
|
|
|
nklist = kmemdup(klist, size, GFP_KERNEL);
|
2006-01-08 02:02:45 -07:00
|
|
|
if (!nklist)
|
|
|
|
goto error2;
|
|
|
|
|
|
|
|
/* replace matched key */
|
|
|
|
atomic_inc(&key->usage);
|
|
|
|
nklist->keys[loop] = key;
|
|
|
|
|
|
|
|
rcu_assign_pointer(
|
|
|
|
keyring->payload.subscriptions,
|
|
|
|
nklist);
|
|
|
|
|
|
|
|
/* dispose of the old keyring list and the
|
|
|
|
* displaced key */
|
|
|
|
klist->delkey = loop;
|
|
|
|
call_rcu(&klist->rcu,
|
|
|
|
keyring_unlink_rcu_disposal);
|
|
|
|
|
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/* check that we aren't going to overrun the user's quota */
|
|
|
|
ret = key_payload_reserve(keyring,
|
|
|
|
keyring->datalen + KEYQUOTA_LINK_BYTES);
|
|
|
|
if (ret < 0)
|
|
|
|
goto error2;
|
|
|
|
|
|
|
|
klist = keyring->payload.subscriptions;
|
|
|
|
|
|
|
|
if (klist && klist->nkeys < klist->maxkeys) {
|
|
|
|
/* there's sufficient slack space to add directly */
|
|
|
|
atomic_inc(&key->usage);
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
klist->keys[klist->nkeys] = key;
|
|
|
|
smp_wmb();
|
|
|
|
klist->nkeys++;
|
|
|
|
smp_wmb();
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
else {
|
|
|
|
/* grow the key list */
|
|
|
|
max = 4;
|
|
|
|
if (klist)
|
|
|
|
max += klist->maxkeys;
|
|
|
|
|
|
|
|
ret = -ENFILE;
|
2005-06-23 22:00:49 -07:00
|
|
|
if (max > 65535)
|
|
|
|
goto error3;
|
2005-07-07 17:57:03 -07:00
|
|
|
size = sizeof(*klist) + sizeof(struct key *) * max;
|
2005-04-16 15:20:36 -07:00
|
|
|
if (size > PAGE_SIZE)
|
|
|
|
goto error3;
|
|
|
|
|
|
|
|
ret = -ENOMEM;
|
|
|
|
nklist = kmalloc(size, GFP_KERNEL);
|
|
|
|
if (!nklist)
|
|
|
|
goto error3;
|
|
|
|
nklist->maxkeys = max;
|
|
|
|
nklist->nkeys = 0;
|
|
|
|
|
|
|
|
if (klist) {
|
|
|
|
nklist->nkeys = klist->nkeys;
|
|
|
|
memcpy(nklist->keys,
|
|
|
|
klist->keys,
|
|
|
|
sizeof(struct key *) * klist->nkeys);
|
|
|
|
}
|
|
|
|
|
|
|
|
/* add the key into the new space */
|
|
|
|
atomic_inc(&key->usage);
|
|
|
|
nklist->keys[nklist->nkeys++] = key;
|
2005-06-23 22:00:49 -07:00
|
|
|
|
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions, nklist);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
/* dispose of the old keyring list */
|
2005-06-23 22:00:49 -07:00
|
|
|
if (klist)
|
|
|
|
call_rcu(&klist->rcu, keyring_link_rcu_disposal);
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
|
2006-01-08 02:02:45 -07:00
|
|
|
done:
|
|
|
|
ret = 0;
|
|
|
|
error2:
|
2005-04-16 15:20:36 -07:00
|
|
|
up_write(&keyring_serialise_link_sem);
|
2006-01-08 02:02:45 -07:00
|
|
|
error:
|
2005-04-16 15:20:36 -07:00
|
|
|
return ret;
|
|
|
|
|
2006-01-08 02:02:45 -07:00
|
|
|
error3:
|
2005-04-16 15:20:36 -07:00
|
|
|
/* undo the quota changes */
|
|
|
|
key_payload_reserve(keyring,
|
|
|
|
keyring->datalen - KEYQUOTA_LINK_BYTES);
|
|
|
|
goto error2;
|
|
|
|
|
|
|
|
} /* end __key_link() */
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* link a key to a keyring
|
|
|
|
*/
|
|
|
|
int key_link(struct key *keyring, struct key *key)
|
|
|
|
{
|
|
|
|
int ret;
|
|
|
|
|
|
|
|
key_check(keyring);
|
|
|
|
key_check(key);
|
|
|
|
|
|
|
|
down_write(&keyring->sem);
|
|
|
|
ret = __key_link(keyring, key);
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
|
|
|
|
} /* end key_link() */
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(key_link);
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* unlink the first link to a key from a keyring
|
|
|
|
*/
|
|
|
|
int key_unlink(struct key *keyring, struct key *key)
|
|
|
|
{
|
2005-06-23 22:00:49 -07:00
|
|
|
struct keyring_list *klist, *nklist;
|
2005-04-16 15:20:36 -07:00
|
|
|
int loop, ret;
|
|
|
|
|
|
|
|
key_check(keyring);
|
|
|
|
key_check(key);
|
|
|
|
|
|
|
|
ret = -ENOTDIR;
|
|
|
|
if (keyring->type != &key_type_keyring)
|
|
|
|
goto error;
|
|
|
|
|
|
|
|
down_write(&keyring->sem);
|
|
|
|
|
|
|
|
klist = keyring->payload.subscriptions;
|
|
|
|
if (klist) {
|
|
|
|
/* search the keyring for the key */
|
|
|
|
for (loop = 0; loop < klist->nkeys; loop++)
|
|
|
|
if (klist->keys[loop] == key)
|
|
|
|
goto key_is_present;
|
|
|
|
}
|
|
|
|
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
ret = -ENOENT;
|
|
|
|
goto error;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
key_is_present:
|
|
|
|
/* we need to copy the key list for RCU purposes */
|
2005-07-07 17:57:03 -07:00
|
|
|
nklist = kmalloc(sizeof(*klist) +
|
|
|
|
sizeof(struct key *) * klist->maxkeys,
|
2005-06-23 22:00:49 -07:00
|
|
|
GFP_KERNEL);
|
|
|
|
if (!nklist)
|
|
|
|
goto nomem;
|
|
|
|
nklist->maxkeys = klist->maxkeys;
|
|
|
|
nklist->nkeys = klist->nkeys - 1;
|
|
|
|
|
|
|
|
if (loop > 0)
|
|
|
|
memcpy(&nklist->keys[0],
|
|
|
|
&klist->keys[0],
|
2005-07-07 17:57:03 -07:00
|
|
|
loop * sizeof(struct key *));
|
2005-06-23 22:00:49 -07:00
|
|
|
|
|
|
|
if (loop < nklist->nkeys)
|
|
|
|
memcpy(&nklist->keys[loop],
|
|
|
|
&klist->keys[loop + 1],
|
2005-07-07 17:57:03 -07:00
|
|
|
(nklist->nkeys - loop) * sizeof(struct key *));
|
2005-06-23 22:00:49 -07:00
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/* adjust the user's quota */
|
|
|
|
key_payload_reserve(keyring,
|
|
|
|
keyring->datalen - KEYQUOTA_LINK_BYTES);
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions, nklist);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
up_write(&keyring->sem);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
/* schedule for later cleanup */
|
|
|
|
klist->delkey = loop;
|
|
|
|
call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
ret = 0;
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
error:
|
2005-04-16 15:20:36 -07:00
|
|
|
return ret;
|
2005-06-23 22:00:49 -07:00
|
|
|
nomem:
|
|
|
|
ret = -ENOMEM;
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
goto error;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
} /* end key_unlink() */
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(key_unlink);
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* dispose of a keyring list after the RCU grace period, releasing the keys it
|
|
|
|
* links to
|
|
|
|
*/
|
|
|
|
static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist;
|
|
|
|
int loop;
|
|
|
|
|
|
|
|
klist = container_of(rcu, struct keyring_list, rcu);
|
|
|
|
|
|
|
|
for (loop = klist->nkeys - 1; loop >= 0; loop--)
|
|
|
|
key_put(klist->keys[loop]);
|
|
|
|
|
|
|
|
kfree(klist);
|
|
|
|
|
|
|
|
} /* end keyring_clear_rcu_disposal() */
|
|
|
|
|
2005-04-16 15:20:36 -07:00
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* clear the specified process keyring
|
|
|
|
* - implements keyctl(KEYCTL_CLEAR)
|
|
|
|
*/
|
|
|
|
int keyring_clear(struct key *keyring)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist;
|
2005-06-23 22:00:49 -07:00
|
|
|
int ret;
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
ret = -ENOTDIR;
|
|
|
|
if (keyring->type == &key_type_keyring) {
|
|
|
|
/* detach the pointer block with the locks held */
|
|
|
|
down_write(&keyring->sem);
|
|
|
|
|
|
|
|
klist = keyring->payload.subscriptions;
|
|
|
|
if (klist) {
|
|
|
|
/* adjust the quota */
|
|
|
|
key_payload_reserve(keyring,
|
|
|
|
sizeof(struct keyring_list));
|
|
|
|
|
2005-06-23 22:00:49 -07:00
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions,
|
|
|
|
NULL);
|
2005-04-16 15:20:36 -07:00
|
|
|
}
|
|
|
|
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
|
|
|
|
/* free the keys after the locks have been dropped */
|
2005-06-23 22:00:49 -07:00
|
|
|
if (klist)
|
|
|
|
call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
|
2005-04-16 15:20:36 -07:00
|
|
|
|
|
|
|
ret = 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
|
|
|
|
} /* end keyring_clear() */
|
|
|
|
|
|
|
|
EXPORT_SYMBOL(keyring_clear);
|
2006-06-26 00:24:51 -07:00
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
|
|
/*
|
|
|
|
* dispose of the links from a revoked keyring
|
|
|
|
* - called with the key sem write-locked
|
|
|
|
*/
|
|
|
|
static void keyring_revoke(struct key *keyring)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist = keyring->payload.subscriptions;
|
|
|
|
|
|
|
|
/* adjust the quota */
|
|
|
|
key_payload_reserve(keyring, 0);
|
|
|
|
|
|
|
|
if (klist) {
|
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions, NULL);
|
|
|
|
call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
|
|
|
|
}
|
|
|
|
|
|
|
|
} /* end keyring_revoke() */
|
2009-09-02 01:14:00 -07:00
|
|
|
|
|
|
|
/*
|
|
|
|
* Determine whether a key is dead
|
|
|
|
*/
|
|
|
|
static bool key_is_dead(struct key *key, time_t limit)
|
|
|
|
{
|
|
|
|
return test_bit(KEY_FLAG_DEAD, &key->flags) ||
|
|
|
|
(key->expiry > 0 && key->expiry <= limit);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Collect garbage from the contents of a keyring
|
|
|
|
*/
|
|
|
|
void keyring_gc(struct key *keyring, time_t limit)
|
|
|
|
{
|
|
|
|
struct keyring_list *klist, *new;
|
|
|
|
struct key *key;
|
|
|
|
int loop, keep, max;
|
|
|
|
|
2009-09-14 09:26:13 -07:00
|
|
|
kenter("{%x,%s}", key_serial(keyring), keyring->description);
|
2009-09-02 01:14:00 -07:00
|
|
|
|
|
|
|
down_write(&keyring->sem);
|
|
|
|
|
|
|
|
klist = keyring->payload.subscriptions;
|
|
|
|
if (!klist)
|
2009-09-14 09:26:13 -07:00
|
|
|
goto no_klist;
|
2009-09-02 01:14:00 -07:00
|
|
|
|
|
|
|
/* work out how many subscriptions we're keeping */
|
|
|
|
keep = 0;
|
|
|
|
for (loop = klist->nkeys - 1; loop >= 0; loop--)
|
2009-09-14 09:26:13 -07:00
|
|
|
if (!key_is_dead(klist->keys[loop], limit))
|
2009-09-02 01:14:00 -07:00
|
|
|
keep++;
|
|
|
|
|
|
|
|
if (keep == klist->nkeys)
|
|
|
|
goto just_return;
|
|
|
|
|
|
|
|
/* allocate a new keyring payload */
|
|
|
|
max = roundup(keep, 4);
|
|
|
|
new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
|
|
|
|
GFP_KERNEL);
|
|
|
|
if (!new)
|
2009-09-14 09:26:13 -07:00
|
|
|
goto nomem;
|
2009-09-02 01:14:00 -07:00
|
|
|
new->maxkeys = max;
|
|
|
|
new->nkeys = 0;
|
|
|
|
new->delkey = 0;
|
|
|
|
|
|
|
|
/* install the live keys
|
|
|
|
* - must take care as expired keys may be updated back to life
|
|
|
|
*/
|
|
|
|
keep = 0;
|
|
|
|
for (loop = klist->nkeys - 1; loop >= 0; loop--) {
|
|
|
|
key = klist->keys[loop];
|
|
|
|
if (!key_is_dead(key, limit)) {
|
|
|
|
if (keep >= max)
|
|
|
|
goto discard_new;
|
|
|
|
new->keys[keep++] = key_get(key);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
new->nkeys = keep;
|
|
|
|
|
|
|
|
/* adjust the quota */
|
|
|
|
key_payload_reserve(keyring,
|
|
|
|
sizeof(struct keyring_list) +
|
|
|
|
KEYQUOTA_LINK_BYTES * keep);
|
|
|
|
|
|
|
|
if (keep == 0) {
|
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions, NULL);
|
|
|
|
kfree(new);
|
|
|
|
} else {
|
|
|
|
rcu_assign_pointer(keyring->payload.subscriptions, new);
|
|
|
|
}
|
|
|
|
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
|
|
|
|
call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
|
|
|
|
kleave(" [yes]");
|
|
|
|
return;
|
|
|
|
|
|
|
|
discard_new:
|
|
|
|
new->nkeys = keep;
|
|
|
|
keyring_clear_rcu_disposal(&new->rcu);
|
2009-09-14 09:26:13 -07:00
|
|
|
up_write(&keyring->sem);
|
|
|
|
kleave(" [discard]");
|
|
|
|
return;
|
|
|
|
|
2009-09-02 01:14:00 -07:00
|
|
|
just_return:
|
|
|
|
up_write(&keyring->sem);
|
2009-09-14 09:26:13 -07:00
|
|
|
kleave(" [no dead]");
|
|
|
|
return;
|
|
|
|
|
|
|
|
no_klist:
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
kleave(" [no_klist]");
|
|
|
|
return;
|
|
|
|
|
|
|
|
nomem:
|
|
|
|
up_write(&keyring->sem);
|
|
|
|
kleave(" [oom]");
|
2009-09-02 01:14:00 -07:00
|
|
|
}
|