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;
45 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
46 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
47 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
48 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
49 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
50 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
51 #define KEY_POS_ALL 0x3f000000
53 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
54 #define KEY_USR_READ 0x00020000
55 #define KEY_USR_WRITE 0x00040000
56 #define KEY_USR_SEARCH 0x00080000
57 #define KEY_USR_LINK 0x00100000
58 #define KEY_USR_SETATTR 0x00200000
59 #define KEY_USR_ALL 0x003f0000
61 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
62 #define KEY_GRP_READ 0x00000200
63 #define KEY_GRP_WRITE 0x00000400
64 #define KEY_GRP_SEARCH 0x00000800
65 #define KEY_GRP_LINK 0x00001000
66 #define KEY_GRP_SETATTR 0x00002000
67 #define KEY_GRP_ALL 0x00003f00
69 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
70 #define KEY_OTH_READ 0x00000002
71 #define KEY_OTH_WRITE 0x00000004
72 #define KEY_OTH_SEARCH 0x00000008
73 #define KEY_OTH_LINK 0x00000010
74 #define KEY_OTH_SETATTR 0x00000020
75 #define KEY_OTH_ALL 0x0000003f
77 #define KEY_PERM_UNDEF 0xffffffff
93 bool removed; /* T when subject removed */
96 struct keyring_index_key {
97 /* [!] If this structure is altered, the union in struct key must change too! */
98 unsigned long hash; /* Hash value */
101 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
103 char desc[sizeof(long) - 1]; /* First few chars of description */
105 char desc[sizeof(long) - 1]; /* First few chars of description */
111 struct key_type *type;
112 struct key_tag *domain_tag; /* Domain of operation */
113 const char *description;
117 void __rcu *rcu_data0;
121 /*****************************************************************************/
123 * key reference with possession attribute handling
125 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
126 * defined. This is because we abuse the bottom bit of the reference to carry a
127 * flag to indicate whether the calling process possesses that key in one of
130 * the key_ref_t has been made a separate type so that the compiler can reject
131 * attempts to dereference it without proper conversion.
133 * the three functions are used to assemble and disassemble references
135 typedef struct __key_reference_with_attributes *key_ref_t;
137 static inline key_ref_t make_key_ref(const struct key *key,
140 return (key_ref_t) ((unsigned long) key | possession);
143 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
145 return (struct key *) ((unsigned long) key_ref & ~1UL);
148 static inline bool is_key_possessed(const key_ref_t key_ref)
150 return (unsigned long) key_ref & 1UL;
153 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
154 const struct key_type *type,
155 const union key_payload *payload,
156 struct key *restriction_key);
158 struct key_restriction {
159 key_restrict_link_func_t check;
161 struct key_type *keytype;
165 KEY_IS_UNINSTANTIATED,
166 KEY_IS_POSITIVE, /* Positively instantiated */
169 /*****************************************************************************/
171 * authentication token / access credential / keyring
172 * - types of key include:
174 * - disk encryption IDs
175 * - Kerberos TGTs and tickets
178 refcount_t usage; /* number of references */
179 key_serial_t serial; /* key serial number */
181 struct list_head graveyard_link;
182 struct rb_node serial_node;
184 struct rw_semaphore sem; /* change vs change sem */
185 struct key_user *user; /* owner of this key */
186 void *security; /* security data for this key */
188 time64_t expiry; /* time at which key expires (or 0) */
189 time64_t revoked_at; /* time at which key was revoked */
191 time64_t last_used_at; /* last time used for LRU keyring discard */
194 key_perm_t perm; /* access permissions */
195 unsigned short quotalen; /* length added to quota */
196 unsigned short datalen; /* payload data length
197 * - may not match RCU dereferenced payload
198 * - payload should contain own length
200 short state; /* Key state (+) or rejection error (-) */
204 #define KEY_DEBUG_MAGIC 0x18273645u
207 unsigned long flags; /* status flags (change with bitops) */
208 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
209 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
210 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
211 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
212 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
213 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
214 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
215 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
216 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
217 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
219 /* the key type and key description string
220 * - the desc is used to match a key against search criteria
221 * - it should be a printable string
222 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
225 struct keyring_index_key index_key;
228 unsigned long len_desc;
229 struct key_type *type; /* type of key */
230 struct key_tag *domain_tag; /* Domain of operation */
236 * - this is used to hold the data actually used in cryptography or
240 union key_payload payload;
243 struct list_head name_link;
244 struct assoc_array keys;
248 /* This is set on a keyring to restrict the addition of a link to a key
249 * to it. If this structure isn't provided then it is assumed that the
250 * keyring is open to any addition. It is ignored for non-keyring
251 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
254 * This is intended for use with rings of trusted keys whereby addition
255 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
256 * overrides this, allowing the kernel to add extra keys without
259 struct key_restriction *restrict_link;
262 extern struct key *key_alloc(struct key_type *type,
264 kuid_t uid, kgid_t gid,
265 const struct cred *cred,
268 struct key_restriction *restrict_link);
271 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
272 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
273 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
274 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
275 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
276 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
278 extern void key_revoke(struct key *key);
279 extern void key_invalidate(struct key *key);
280 extern void key_put(struct key *key);
281 extern bool key_put_tag(struct key_tag *tag);
282 extern void key_remove_domain(struct key_tag *domain_tag);
284 static inline struct key *__key_get(struct key *key)
286 refcount_inc(&key->usage);
290 static inline struct key *key_get(struct key *key)
292 return key ? __key_get(key) : key;
295 static inline void key_ref_put(key_ref_t key_ref)
297 key_put(key_ref_to_ptr(key_ref));
300 extern struct key *request_key_tag(struct key_type *type,
301 const char *description,
302 struct key_tag *domain_tag,
303 const char *callout_info);
305 extern struct key *request_key_rcu(struct key_type *type,
306 const char *description,
307 struct key_tag *domain_tag);
309 extern struct key *request_key_with_auxdata(struct key_type *type,
310 const char *description,
311 struct key_tag *domain_tag,
312 const void *callout_info,
317 * request_key - Request a key and wait for construction
318 * @type: Type of key.
319 * @description: The searchable description of the key.
320 * @callout_info: The data to pass to the instantiation upcall (or NULL).
322 * As for request_key_tag(), but with the default global domain tag.
324 static inline struct key *request_key(struct key_type *type,
325 const char *description,
326 const char *callout_info)
328 return request_key_tag(type, description, NULL, callout_info);
333 * request_key_net - Request a key for a net namespace and wait for construction
334 * @type: Type of key.
335 * @description: The searchable description of the key.
336 * @net: The network namespace that is the key's domain of operation.
337 * @callout_info: The data to pass to the instantiation upcall (or NULL).
339 * As for request_key() except that it does not add the returned key to a
340 * keyring if found, new keys are always allocated in the user's quota, the
341 * callout_info must be a NUL-terminated string and no auxiliary data can be
342 * passed. Only keys that operate the specified network namespace are used.
344 * Furthermore, it then works as wait_for_key_construction() to wait for the
345 * completion of keys undergoing construction with a non-interruptible wait.
347 #define request_key_net(type, description, net, callout_info) \
348 request_key_tag(type, description, net->key_domain, callout_info);
349 #endif /* CONFIG_NET */
351 extern int wait_for_key_construction(struct key *key, bool intr);
353 extern int key_validate(const struct key *key);
355 extern key_ref_t key_create_or_update(key_ref_t keyring,
357 const char *description,
361 unsigned long flags);
363 extern int key_update(key_ref_t key,
367 extern int key_link(struct key *keyring,
370 extern int key_move(struct key *key,
371 struct key *from_keyring,
372 struct key *to_keyring,
375 extern int key_unlink(struct key *keyring,
378 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
379 const struct cred *cred,
382 struct key_restriction *restrict_link,
385 extern int restrict_link_reject(struct key *keyring,
386 const struct key_type *type,
387 const union key_payload *payload,
388 struct key *restriction_key);
390 extern int keyring_clear(struct key *keyring);
392 extern key_ref_t keyring_search(key_ref_t keyring,
393 struct key_type *type,
394 const char *description,
397 extern int keyring_add_key(struct key *keyring,
400 extern int keyring_restrict(key_ref_t keyring, const char *type,
401 const char *restriction);
403 extern struct key *key_lookup(key_serial_t id);
405 static inline key_serial_t key_serial(const struct key *key)
407 return key ? key->serial : 0;
410 extern void key_set_timeout(struct key *, unsigned);
412 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
414 extern void key_free_user_ns(struct user_namespace *);
417 * The permissions required on a key that we're looking up.
419 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
420 #define KEY_NEED_READ 0x02 /* Require permission to read content */
421 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
422 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
423 #define KEY_NEED_LINK 0x10 /* Require permission to link */
424 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
425 #define KEY_NEED_ALL 0x3f /* All the above permissions */
427 static inline short key_read_state(const struct key *key)
429 /* Barrier versus mark_key_instantiated(). */
430 return smp_load_acquire(&key->state);
434 * key_is_positive - Determine if a key has been positively instantiated
435 * @key: The key to check.
437 * Return true if the specified key has been positively instantiated, false
440 static inline bool key_is_positive(const struct key *key)
442 return key_read_state(key) == KEY_IS_POSITIVE;
445 static inline bool key_is_negative(const struct key *key)
447 return key_read_state(key) < 0;
450 #define dereference_key_rcu(KEY) \
451 (rcu_dereference((KEY)->payload.rcu_data0))
453 #define dereference_key_locked(KEY) \
454 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
455 rwsem_is_locked(&((struct key *)(KEY))->sem)))
457 #define rcu_assign_keypointer(KEY, PAYLOAD) \
459 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
463 extern struct ctl_table key_sysctls[];
466 * the userspace interface
468 extern int install_thread_keyring_to_cred(struct cred *cred);
469 extern void key_fsuid_changed(struct cred *new_cred);
470 extern void key_fsgid_changed(struct cred *new_cred);
471 extern void key_init(void);
473 #else /* CONFIG_KEYS */
475 #define key_validate(k) 0
476 #define key_serial(k) 0
477 #define key_get(k) ({ NULL; })
478 #define key_revoke(k) do { } while(0)
479 #define key_invalidate(k) do { } while(0)
480 #define key_put(k) do { } while(0)
481 #define key_ref_put(k) do { } while(0)
482 #define make_key_ref(k, p) NULL
483 #define key_ref_to_ptr(k) NULL
484 #define is_key_possessed(k) 0
485 #define key_fsuid_changed(c) do { } while(0)
486 #define key_fsgid_changed(c) do { } while(0)
487 #define key_init() do { } while(0)
488 #define key_free_user_ns(ns) do { } while(0)
489 #define key_remove_domain(d) do { } while(0)
491 #endif /* CONFIG_KEYS */
492 #endif /* __KERNEL__ */
493 #endif /* _LINUX_KEY_H */