1 /* Authentication token and access key management
3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 * See Documentation/security/keys/core.rst for information on keys/keyrings.
18 #include <linux/types.h>
19 #include <linux/list.h>
20 #include <linux/rbtree.h>
21 #include <linux/rcupdate.h>
22 #include <linux/sysctl.h>
23 #include <linux/rwsem.h>
24 #include <linux/atomic.h>
25 #include <linux/assoc_array.h>
26 #include <linux/refcount.h>
27 #include <linux/time64.h>
30 #include <linux/uidgid.h>
32 /* key handle serial number */
33 typedef int32_t key_serial_t
;
35 /* key handle permissions mask */
36 typedef uint32_t key_perm_t
;
44 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
45 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
46 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
47 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
48 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
49 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
50 #define KEY_POS_ALL 0x3f000000
52 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
53 #define KEY_USR_READ 0x00020000
54 #define KEY_USR_WRITE 0x00040000
55 #define KEY_USR_SEARCH 0x00080000
56 #define KEY_USR_LINK 0x00100000
57 #define KEY_USR_SETATTR 0x00200000
58 #define KEY_USR_ALL 0x003f0000
60 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
61 #define KEY_GRP_READ 0x00000200
62 #define KEY_GRP_WRITE 0x00000400
63 #define KEY_GRP_SEARCH 0x00000800
64 #define KEY_GRP_LINK 0x00001000
65 #define KEY_GRP_SETATTR 0x00002000
66 #define KEY_GRP_ALL 0x00003f00
68 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
69 #define KEY_OTH_READ 0x00000002
70 #define KEY_OTH_WRITE 0x00000004
71 #define KEY_OTH_SEARCH 0x00000008
72 #define KEY_OTH_LINK 0x00000010
73 #define KEY_OTH_SETATTR 0x00000020
74 #define KEY_OTH_ALL 0x0000003f
76 #define KEY_PERM_UNDEF 0xffffffff
88 struct keyring_index_key
{
89 struct key_type
*type
;
90 const char *description
;
95 void __rcu
*rcu_data0
;
99 /*****************************************************************************/
101 * key reference with possession attribute handling
103 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
104 * defined. This is because we abuse the bottom bit of the reference to carry a
105 * flag to indicate whether the calling process possesses that key in one of
108 * the key_ref_t has been made a separate type so that the compiler can reject
109 * attempts to dereference it without proper conversion.
111 * the three functions are used to assemble and disassemble references
113 typedef struct __key_reference_with_attributes
*key_ref_t
;
115 static inline key_ref_t
make_key_ref(const struct key
*key
,
118 return (key_ref_t
) ((unsigned long) key
| possession
);
121 static inline struct key
*key_ref_to_ptr(const key_ref_t key_ref
)
123 return (struct key
*) ((unsigned long) key_ref
& ~1UL);
126 static inline bool is_key_possessed(const key_ref_t key_ref
)
128 return (unsigned long) key_ref
& 1UL;
131 typedef int (*key_restrict_link_func_t
)(struct key
*dest_keyring
,
132 const struct key_type
*type
,
133 const union key_payload
*payload
,
134 struct key
*restriction_key
);
136 struct key_restriction
{
137 key_restrict_link_func_t check
;
139 struct key_type
*keytype
;
143 KEY_IS_UNINSTANTIATED
,
144 KEY_IS_POSITIVE
, /* Positively instantiated */
147 /*****************************************************************************/
149 * authentication token / access credential / keyring
150 * - types of key include:
152 * - disk encryption IDs
153 * - Kerberos TGTs and tickets
156 refcount_t usage
; /* number of references */
157 key_serial_t serial
; /* key serial number */
159 struct list_head graveyard_link
;
160 struct rb_node serial_node
;
162 struct rw_semaphore sem
; /* change vs change sem */
163 struct key_user
*user
; /* owner of this key */
164 void *security
; /* security data for this key */
166 time64_t expiry
; /* time at which key expires (or 0) */
167 time64_t revoked_at
; /* time at which key was revoked */
169 time64_t last_used_at
; /* last time used for LRU keyring discard */
172 key_perm_t perm
; /* access permissions */
173 unsigned short quotalen
; /* length added to quota */
174 unsigned short datalen
; /* payload data length
175 * - may not match RCU dereferenced payload
176 * - payload should contain own length
178 short state
; /* Key state (+) or rejection error (-) */
182 #define KEY_DEBUG_MAGIC 0x18273645u
185 unsigned long flags
; /* status flags (change with bitops) */
186 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
187 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
188 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
189 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
190 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
191 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
192 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
193 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
194 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
195 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
197 /* the key type and key description string
198 * - the desc is used to match a key against search criteria
199 * - it should be a printable string
200 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
203 struct keyring_index_key index_key
;
205 struct key_type
*type
; /* type of key */
211 * - this is used to hold the data actually used in cryptography or
215 union key_payload payload
;
218 struct list_head name_link
;
219 struct assoc_array keys
;
223 /* This is set on a keyring to restrict the addition of a link to a key
224 * to it. If this structure isn't provided then it is assumed that the
225 * keyring is open to any addition. It is ignored for non-keyring
226 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
229 * This is intended for use with rings of trusted keys whereby addition
230 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
231 * overrides this, allowing the kernel to add extra keys without
234 struct key_restriction
*restrict_link
;
237 extern struct key
*key_alloc(struct key_type
*type
,
239 kuid_t uid
, kgid_t gid
,
240 const struct cred
*cred
,
243 struct key_restriction
*restrict_link
);
246 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
247 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
248 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
249 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
250 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
251 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
253 extern void key_revoke(struct key
*key
);
254 extern void key_invalidate(struct key
*key
);
255 extern void key_put(struct key
*key
);
257 static inline struct key
*__key_get(struct key
*key
)
259 refcount_inc(&key
->usage
);
263 static inline struct key
*key_get(struct key
*key
)
265 return key
? __key_get(key
) : key
;
268 static inline void key_ref_put(key_ref_t key_ref
)
270 key_put(key_ref_to_ptr(key_ref
));
273 extern struct key
*request_key(struct key_type
*type
,
274 const char *description
,
275 const char *callout_info
);
277 extern struct key
*request_key_with_auxdata(struct key_type
*type
,
278 const char *description
,
279 const void *callout_info
,
283 extern struct key
*request_key_async(struct key_type
*type
,
284 const char *description
,
285 const void *callout_info
,
288 extern struct key
*request_key_async_with_auxdata(struct key_type
*type
,
289 const char *description
,
290 const void *callout_info
,
294 extern int wait_for_key_construction(struct key
*key
, bool intr
);
296 extern int key_validate(const struct key
*key
);
298 extern key_ref_t
key_create_or_update(key_ref_t keyring
,
300 const char *description
,
304 unsigned long flags
);
306 extern int key_update(key_ref_t key
,
310 extern int key_link(struct key
*keyring
,
313 extern int key_unlink(struct key
*keyring
,
316 extern struct key
*keyring_alloc(const char *description
, kuid_t uid
, kgid_t gid
,
317 const struct cred
*cred
,
320 struct key_restriction
*restrict_link
,
323 extern int restrict_link_reject(struct key
*keyring
,
324 const struct key_type
*type
,
325 const union key_payload
*payload
,
326 struct key
*restriction_key
);
328 extern int keyring_clear(struct key
*keyring
);
330 extern key_ref_t
keyring_search(key_ref_t keyring
,
331 struct key_type
*type
,
332 const char *description
);
334 extern int keyring_add_key(struct key
*keyring
,
337 extern int keyring_restrict(key_ref_t keyring
, const char *type
,
338 const char *restriction
);
340 extern struct key
*key_lookup(key_serial_t id
);
342 static inline key_serial_t
key_serial(const struct key
*key
)
344 return key
? key
->serial
: 0;
347 extern void key_set_timeout(struct key
*, unsigned);
349 extern key_ref_t
lookup_user_key(key_serial_t id
, unsigned long flags
,
353 * The permissions required on a key that we're looking up.
355 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
356 #define KEY_NEED_READ 0x02 /* Require permission to read content */
357 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
358 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
359 #define KEY_NEED_LINK 0x10 /* Require permission to link */
360 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
361 #define KEY_NEED_ALL 0x3f /* All the above permissions */
363 static inline short key_read_state(const struct key
*key
)
365 /* Barrier versus mark_key_instantiated(). */
366 return smp_load_acquire(&key
->state
);
370 * key_is_positive - Determine if a key has been positively instantiated
371 * @key: The key to check.
373 * Return true if the specified key has been positively instantiated, false
376 static inline bool key_is_positive(const struct key
*key
)
378 return key_read_state(key
) == KEY_IS_POSITIVE
;
381 static inline bool key_is_negative(const struct key
*key
)
383 return key_read_state(key
) < 0;
386 #define dereference_key_rcu(KEY) \
387 (rcu_dereference((KEY)->payload.rcu_data0))
389 #define dereference_key_locked(KEY) \
390 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
391 rwsem_is_locked(&((struct key *)(KEY))->sem)))
393 #define rcu_assign_keypointer(KEY, PAYLOAD) \
395 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
399 extern struct ctl_table key_sysctls
[];
402 * the userspace interface
404 extern int install_thread_keyring_to_cred(struct cred
*cred
);
405 extern void key_fsuid_changed(struct task_struct
*tsk
);
406 extern void key_fsgid_changed(struct task_struct
*tsk
);
407 extern void key_init(void);
409 #else /* CONFIG_KEYS */
411 #define key_validate(k) 0
412 #define key_serial(k) 0
413 #define key_get(k) ({ NULL; })
414 #define key_revoke(k) do { } while(0)
415 #define key_invalidate(k) do { } while(0)
416 #define key_put(k) do { } while(0)
417 #define key_ref_put(k) do { } while(0)
418 #define make_key_ref(k, p) NULL
419 #define key_ref_to_ptr(k) NULL
420 #define is_key_possessed(k) 0
421 #define key_fsuid_changed(t) do { } while(0)
422 #define key_fsgid_changed(t) do { } while(0)
423 #define key_init() do { } while(0)
425 #endif /* CONFIG_KEYS */
426 #endif /* __KERNEL__ */
427 #endif /* _LINUX_KEY_H */