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/* Authentication token and access key management
* Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (
* 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.
* See Documentation/security/keys.txt for information on keys/keyrings.
#ifndef _LINUX_KEY_H
#define _LINUX_KEY_H
#include <linux/types.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>
#include <linux/sysctl.h>
#include <linux/rwsem.h>
#include <linux/atomic.h>
#ifdef __KERNEL__
/* key handle serial number */
typedef int32_t key_serial_t;
/* key handle permissions mask */
typedef uint32_t key_perm_t;
struct key;
#define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
#define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
#define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
#define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
#define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
#define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
#define KEY_POS_ALL 0x3f000000
#define KEY_USR_VIEW 0x00010000 /* user permissions... */
#define KEY_USR_READ 0x00020000
#define KEY_USR_WRITE 0x00040000
#define KEY_USR_SEARCH 0x00080000
#define KEY_USR_LINK 0x00100000
#define KEY_USR_SETATTR 0x00200000
#define KEY_USR_ALL 0x003f0000
#define KEY_GRP_VIEW 0x00000100 /* group permissions... */
#define KEY_GRP_READ 0x00000200
#define KEY_GRP_WRITE 0x00000400
#define KEY_GRP_SEARCH 0x00000800
#define KEY_GRP_LINK 0x00001000
#define KEY_GRP_SETATTR 0x00002000
#define KEY_GRP_ALL 0x00003f00
#define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
#define KEY_OTH_READ 0x00000002
#define KEY_OTH_WRITE 0x00000004
#define KEY_OTH_SEARCH 0x00000008
#define KEY_OTH_LINK 0x00000010
#define KEY_OTH_SETATTR 0x00000020
#define KEY_OTH_ALL 0x0000003f
#define KEY_PERM_UNDEF 0xffffffff
struct seq_file;
struct user_struct;
struct signal_struct;
struct cred;
struct key_type;
struct key_owner;
struct keyring_list;
struct keyring_name;
* key reference with possession attribute handling
* NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
* defined. This is because we abuse the bottom bit of the reference to carry a
* flag to indicate whether the calling process possesses that key in one of
* its keyrings.
* the key_ref_t has been made a separate type so that the compiler can reject
* attempts to dereference it without proper conversion.
* the three functions are used to assemble and disassemble references
typedef struct __key_reference_with_attributes *key_ref_t;
static inline key_ref_t make_key_ref(const struct key *key,
unsigned long possession)
return (key_ref_t) ((unsigned long) key | possession);
static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
return (struct key *) ((unsigned long) key_ref & ~1UL);
static inline unsigned long is_key_possessed(const key_ref_t key_ref)
return (unsigned long) key_ref & 1UL;
* authentication token / access credential / keyring
* - types of key include:
* - keyrings
* - disk encryption IDs
* - Kerberos TGTs and tickets
struct key {
atomic_t usage; /* number of references */
key_serial_t serial; /* key serial number */
struct rb_node serial_node;
struct key_type *type; /* type of key */
struct rw_semaphore sem; /* change vs change sem */
struct key_user *user; /* owner of this key */
void *security; /* security data for this key */
union {
time_t expiry; /* time at which key expires (or 0) */
time_t revoked_at; /* time at which key was revoked */
uid_t uid;
gid_t gid;
key_perm_t perm; /* access permissions */
unsigned short quotalen; /* length added to quota */
unsigned short datalen; /* payload data length
* - may not match RCU dereferenced payload
* - payload should contain own length
unsigned magic;
#define KEY_DEBUG_MAGIC 0x18273645u
#define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
unsigned long flags; /* status flags (change with bitops) */
#define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
#define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
#define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
#define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
#define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
#define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
/* the description string
* - this is used to match a key against search criteria
* - this should be a printable string
* - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
char *description;
/* type specific data
* - this is used by the keyring type to index the name
union {
struct list_head link;
unsigned long x[2];
void *p[2];
int reject_error;
} type_data;
/* key data
* - this is used to hold the data actually used in cryptography or
* whatever
union {
unsigned long value;
void __rcu *rcudata;
void *data;
struct keyring_list __rcu *subscriptions;
} payload;
extern struct key *key_alloc(struct key_type *type,
const char *desc,
uid_t uid, gid_t gid,
const struct cred *cred,
key_perm_t perm,
unsigned long flags);
#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
extern void key_revoke(struct key *key);
extern void key_put(struct key *key);
static inline struct key *key_get(struct key *key)
if (key)
return key;
static inline void key_ref_put(key_ref_t key_ref)
extern struct key *request_key(struct key_type *type,
const char *description,
const char *callout_info);
extern struct key *request_key_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux);
extern struct key *request_key_async(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len);
extern struct key *request_key_async_with_auxdata(struct key_type *type,
const char *description,
const void *callout_info,
size_t callout_len,
void *aux);
extern int wait_for_key_construction(struct key *key, bool intr);
extern int key_validate(struct key *key);
extern key_ref_t key_create_or_update(key_ref_t keyring,
const char *type,
const char *description,
const void *payload,
size_t plen,
key_perm_t perm,
unsigned long flags);
extern int key_update(key_ref_t key,
const void *payload,
size_t plen);
extern int key_link(struct key *keyring,
struct key *key);
extern int key_unlink(struct key *keyring,
struct key *key);
extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
const struct cred *cred,
unsigned long flags,
struct key *dest);
extern int keyring_clear(struct key *keyring);
extern key_ref_t keyring_search(key_ref_t keyring,
struct key_type *type,
const char *description);
extern int keyring_add_key(struct key *keyring,
struct key *key);
extern struct key *key_lookup(key_serial_t id);
static inline key_serial_t key_serial(const struct key *key)
return key ? key->serial : 0;
* key_is_instantiated - Determine if a key has been positively instantiated
* @key: The key to check.
* Return true if the specified key has been positively instantiated, false
* otherwise.
static inline bool key_is_instantiated(const struct key *key)
return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
!test_bit(KEY_FLAG_NEGATIVE, &key->flags);
#define rcu_dereference_key(KEY) \
(rcu_dereference_protected((KEY)->payload.rcudata, \
rwsem_is_locked(&((struct key *)(KEY))->sem)))
#define rcu_assign_keypointer(KEY, PAYLOAD) \
(rcu_assign_pointer((KEY)->payload.rcudata, PAYLOAD))
extern ctl_table key_sysctls[];
extern void key_replace_session_keyring(void);
* the userspace interface
extern int install_thread_keyring_to_cred(struct cred *cred);
extern void key_fsuid_changed(struct task_struct *tsk);
extern void key_fsgid_changed(struct task_struct *tsk);
extern void key_init(void);
#else /* CONFIG_KEYS */
#define key_validate(k) 0
#define key_serial(k) 0
#define key_get(k) ({ NULL; })
#define key_revoke(k) do { } while(0)
#define key_put(k) do { } while(0)
#define key_ref_put(k) do { } while(0)
#define make_key_ref(k, p) NULL
#define key_ref_to_ptr(k) NULL
#define is_key_possessed(k) 0
#define key_fsuid_changed(t) do { } while(0)
#define key_fsgid_changed(t) do { } while(0)
#define key_init() do { } while(0)
#define key_replace_session_keyring() do { } while(0)
#endif /* CONFIG_KEYS */
#endif /* __KERNEL__ */
#endif /* _LINUX_KEY_H */