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linux/security/keys/internal.h
David Howells 664cceb009 [PATCH] Keys: Add possessor permissions to keys [try #3] 
The attached patch adds extra permission grants to keys for the possessor of a
key in addition to the owner, group and other permissions bits. This makes
SUID binaries easier to support without going as far as labelling keys and key
targets using the LSM facilities.

This patch adds a second "pointer type" to key structures (struct key_ref *)
that can have the bottom bit of the address set to indicate the possession of
a key. This is propagated through searches from the keyring to the discovered
key. It has been made a separate type so that the compiler can spot attempts
to dereference a potentially incorrect pointer.

The "possession" attribute can't be attached to a key structure directly as
it's not an intrinsic property of a key.

Pointers to keys have been replaced with struct key_ref *'s wherever
possession information needs to be passed through.

This does assume that the bottom bit of the pointer will always be zero on
return from kmem_cache_alloc().

The key reference type has been made into a typedef so that at least it can be
located in the sources, even though it's basically a pointer to an undefined
type. I've also renamed the accessor functions to be more useful, and all
reference variables should now end in "_ref".

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 09:10:47 -07:00

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/* internal.h: authentication token and access key management internal defs
*
* Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _INTERNAL_H
#define _INTERNAL_H
#include <linux/key.h>
#include <linux/key-ui.h>
#if 0
#define kenter(FMT, a...) printk("==> %s("FMT")\n",__FUNCTION__ , ## a)
#define kleave(FMT, a...) printk("<== %s()"FMT"\n",__FUNCTION__ , ## a)
#define kdebug(FMT, a...) printk(FMT"\n" , ## a)
#else
#define kenter(FMT, a...) do {} while(0)
#define kleave(FMT, a...) do {} while(0)
#define kdebug(FMT, a...) do {} while(0)
#endif
extern struct key_type key_type_dead;
extern struct key_type key_type_user;
/*****************************************************************************/
/*
* keep track of keys for a user
* - this needs to be separate to user_struct to avoid a refcount-loop
* (user_struct pins some keyrings which pin this struct)
* - this also keeps track of keys under request from userspace for this UID
*/
struct key_user {
struct rb_node node;
struct list_head consq; /* construction queue */
spinlock_t lock;
atomic_t usage; /* for accessing qnkeys & qnbytes */
atomic_t nkeys; /* number of keys */
atomic_t nikeys; /* number of instantiated keys */
uid_t uid;
int qnkeys; /* number of keys allocated to this user */
int qnbytes; /* number of bytes allocated to this user */
};
#define KEYQUOTA_MAX_KEYS 100
#define KEYQUOTA_MAX_BYTES 10000
#define KEYQUOTA_LINK_BYTES 4 /* a link in a keyring is worth 4 bytes */
extern struct rb_root key_user_tree;
extern spinlock_t key_user_lock;
extern struct key_user root_key_user;
extern struct key_user *key_user_lookup(uid_t uid);
extern void key_user_put(struct key_user *user);
extern struct rb_root key_serial_tree;
extern spinlock_t key_serial_lock;
extern struct semaphore key_alloc_sem;
extern struct rw_semaphore key_construction_sem;
extern wait_queue_head_t request_key_conswq;
extern void keyring_publish_name(struct key *keyring);
extern int __key_link(struct key *keyring, struct key *key);
extern key_ref_t __keyring_search_one(key_ref_t keyring_ref,
const struct key_type *type,
const char *description,
key_perm_t perm);
extern struct key *keyring_search_instkey(struct key *keyring,
key_serial_t target_id);
typedef int (*key_match_func_t)(const struct key *, const void *);
extern key_ref_t keyring_search_aux(key_ref_t keyring_ref,
struct task_struct *tsk,
struct key_type *type,
const void *description,
key_match_func_t match);
extern key_ref_t search_process_keyrings(struct key_type *type,
const void *description,
key_match_func_t match,
struct task_struct *tsk);
extern struct key *find_keyring_by_name(const char *name, key_serial_t bound);
extern int install_thread_keyring(struct task_struct *tsk);
extern int install_process_keyring(struct task_struct *tsk);
extern struct key *request_key_and_link(struct key_type *type,
const char *description,
const char *callout_info,
struct key *dest_keyring);
/*
* request_key authorisation
*/
struct request_key_auth {
struct key *target_key;
struct task_struct *context;
pid_t pid;
};
extern struct key_type key_type_request_key_auth;
extern struct key *request_key_auth_new(struct key *target,
struct key **_rkakey);
extern struct key *key_get_instantiation_authkey(key_serial_t target_id);
/*
* keyctl functions
*/
extern long keyctl_get_keyring_ID(key_serial_t, int);
extern long keyctl_join_session_keyring(const char __user *);
extern long keyctl_update_key(key_serial_t, const void __user *, size_t);
extern long keyctl_revoke_key(key_serial_t);
extern long keyctl_keyring_clear(key_serial_t);
extern long keyctl_keyring_link(key_serial_t, key_serial_t);
extern long keyctl_keyring_unlink(key_serial_t, key_serial_t);
extern long keyctl_describe_key(key_serial_t, char __user *, size_t);
extern long keyctl_keyring_search(key_serial_t, const char __user *,
const char __user *, key_serial_t);
extern long keyctl_read_key(key_serial_t, char __user *, size_t);
extern long keyctl_chown_key(key_serial_t, uid_t, gid_t);
extern long keyctl_setperm_key(key_serial_t, key_perm_t);
extern long keyctl_instantiate_key(key_serial_t, const void __user *,
size_t, key_serial_t);
extern long keyctl_negate_key(key_serial_t, unsigned, key_serial_t);
extern long keyctl_set_reqkey_keyring(int);
/*
* debugging key validation
*/
#ifdef KEY_DEBUGGING
extern void __key_check(const struct key *);
static inline void key_check(const struct key *key)
{
if (key && (IS_ERR(key) || key->magic != KEY_DEBUG_MAGIC))
__key_check(key);
}
#else
#define key_check(key) do {} while(0)
#endif
#endif /* _INTERNAL_H */
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