1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Authentication token and access key management
3 *
4 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * See Documentation/security/keys/core.rst for information on keys/keyrings.
8 */
9
10 #ifndef _LINUX_KEY_H
11 #define _LINUX_KEY_H
12
13 #include <linux/types.h>
14 #include <linux/list.h>
15 #include <linux/rbtree.h>
16 #include <linux/rcupdate.h>
17 #include <linux/sysctl.h>
18 #include <linux/rwsem.h>
19 #include <linux/atomic.h>
20 #include <linux/assoc_array.h>
21 #include <linux/refcount.h>
22 #include <linux/time64.h>
23
24 #ifdef __KERNEL__
25 #include <linux/uidgid.h>
26
27 /* key handle serial number */
28 typedef int32_t key_serial_t;
29
30 /* key handle permissions mask */
31 typedef uint32_t key_perm_t;
32
33 struct key;
34 struct net;
35
36 #ifdef CONFIG_KEYS
37
38 #undef KEY_DEBUGGING
39
40 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
41 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
42 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
43 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
44 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
45 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
46 #define KEY_POS_ALL 0x3f000000
47
48 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
49 #define KEY_USR_READ 0x00020000
50 #define KEY_USR_WRITE 0x00040000
51 #define KEY_USR_SEARCH 0x00080000
52 #define KEY_USR_LINK 0x00100000
53 #define KEY_USR_SETATTR 0x00200000
54 #define KEY_USR_ALL 0x003f0000
55
56 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
57 #define KEY_GRP_READ 0x00000200
58 #define KEY_GRP_WRITE 0x00000400
59 #define KEY_GRP_SEARCH 0x00000800
60 #define KEY_GRP_LINK 0x00001000
61 #define KEY_GRP_SETATTR 0x00002000
62 #define KEY_GRP_ALL 0x00003f00
63
64 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
65 #define KEY_OTH_READ 0x00000002
66 #define KEY_OTH_WRITE 0x00000004
67 #define KEY_OTH_SEARCH 0x00000008
68 #define KEY_OTH_LINK 0x00000010
69 #define KEY_OTH_SETATTR 0x00000020
70 #define KEY_OTH_ALL 0x0000003f
71
72 #define KEY_PERM_UNDEF 0xffffffff
73
74 /*
75 * The permissions required on a key that we're looking up.
76 */
77 enum key_need_perm {
78 KEY_NEED_UNSPECIFIED, /* Needed permission unspecified */
79 KEY_NEED_VIEW, /* Require permission to view attributes */
80 KEY_NEED_READ, /* Require permission to read content */
81 KEY_NEED_WRITE, /* Require permission to update / modify */
82 KEY_NEED_SEARCH, /* Require permission to search (keyring) or find (key) */
83 KEY_NEED_LINK, /* Require permission to link */
84 KEY_NEED_SETATTR, /* Require permission to change attributes */
85 KEY_NEED_UNLINK, /* Require permission to unlink key */
86 KEY_SYSADMIN_OVERRIDE, /* Special: override by CAP_SYS_ADMIN */
87 KEY_AUTHTOKEN_OVERRIDE, /* Special: override by possession of auth token */
88 KEY_DEFER_PERM_CHECK, /* Special: permission check is deferred */
89 };
90
91 enum key_lookup_flag {
92 KEY_LOOKUP_CREATE = 0x01,
93 KEY_LOOKUP_PARTIAL = 0x02,
94 KEY_LOOKUP_ALL = (KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL),
95 };
96
97 struct seq_file;
98 struct user_struct;
99 struct signal_struct;
100 struct cred;
101
102 struct key_type;
103 struct key_owner;
104 struct key_tag;
105 struct keyring_list;
106 struct keyring_name;
107
108 struct key_tag {
109 struct rcu_head rcu;
110 refcount_t usage;
111 bool removed; /* T when subject removed */
112 };
113
114 struct keyring_index_key {
115 /* [!] If this structure is altered, the union in struct key must change too! */
116 unsigned long hash; /* Hash value */
117 union {
118 struct {
119 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
120 u16 desc_len;
121 char desc[sizeof(long) - 2]; /* First few chars of description */
122 #else
123 char desc[sizeof(long) - 2]; /* First few chars of description */
124 u16 desc_len;
125 #endif
126 };
127 unsigned long x;
128 };
129 struct key_type *type;
130 struct key_tag *domain_tag; /* Domain of operation */
131 const char *description;
132 };
133
134 union key_payload {
135 void __rcu *rcu_data0;
136 void *data[4];
137 };
138
139 /*****************************************************************************/
140 /*
141 * key reference with possession attribute handling
142 *
143 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
144 * defined. This is because we abuse the bottom bit of the reference to carry a
145 * flag to indicate whether the calling process possesses that key in one of
146 * its keyrings.
147 *
148 * the key_ref_t has been made a separate type so that the compiler can reject
149 * attempts to dereference it without proper conversion.
150 *
151 * the three functions are used to assemble and disassemble references
152 */
153 typedef struct __key_reference_with_attributes *key_ref_t;
154
make_key_ref(const struct key * key,bool possession)155 static inline key_ref_t make_key_ref(const struct key *key,
156 bool possession)
157 {
158 return (key_ref_t) ((unsigned long) key | possession);
159 }
160
key_ref_to_ptr(const key_ref_t key_ref)161 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
162 {
163 return (struct key *) ((unsigned long) key_ref & ~1UL);
164 }
165
is_key_possessed(const key_ref_t key_ref)166 static inline bool is_key_possessed(const key_ref_t key_ref)
167 {
168 return (unsigned long) key_ref & 1UL;
169 }
170
171 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
172 const struct key_type *type,
173 const union key_payload *payload,
174 struct key *restriction_key);
175
176 struct key_restriction {
177 key_restrict_link_func_t check;
178 struct key *key;
179 struct key_type *keytype;
180 };
181
182 enum key_state {
183 KEY_IS_UNINSTANTIATED,
184 KEY_IS_POSITIVE, /* Positively instantiated */
185 };
186
187 /*****************************************************************************/
188 /*
189 * authentication token / access credential / keyring
190 * - types of key include:
191 * - keyrings
192 * - disk encryption IDs
193 * - Kerberos TGTs and tickets
194 */
195 struct key {
196 refcount_t usage; /* number of references */
197 key_serial_t serial; /* key serial number */
198 union {
199 struct list_head graveyard_link;
200 struct rb_node serial_node;
201 };
202 #ifdef CONFIG_KEY_NOTIFICATIONS
203 struct watch_list *watchers; /* Entities watching this key for changes */
204 #endif
205 struct rw_semaphore sem; /* change vs change sem */
206 struct key_user *user; /* owner of this key */
207 void *security; /* security data for this key */
208 union {
209 time64_t expiry; /* time at which key expires (or 0) */
210 time64_t revoked_at; /* time at which key was revoked */
211 };
212 time64_t last_used_at; /* last time used for LRU keyring discard */
213 kuid_t uid;
214 kgid_t gid;
215 key_perm_t perm; /* access permissions */
216 unsigned short quotalen; /* length added to quota */
217 unsigned short datalen; /* payload data length
218 * - may not match RCU dereferenced payload
219 * - payload should contain own length
220 */
221 short state; /* Key state (+) or rejection error (-) */
222
223 #ifdef KEY_DEBUGGING
224 unsigned magic;
225 #define KEY_DEBUG_MAGIC 0x18273645u
226 #endif
227
228 unsigned long flags; /* status flags (change with bitops) */
229 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
230 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
231 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
232 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
233 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
234 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
235 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
236 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
237 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
238 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
239
240 /* the key type and key description string
241 * - the desc is used to match a key against search criteria
242 * - it should be a printable string
243 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
244 */
245 union {
246 struct keyring_index_key index_key;
247 struct {
248 unsigned long hash;
249 unsigned long len_desc;
250 struct key_type *type; /* type of key */
251 struct key_tag *domain_tag; /* Domain of operation */
252 char *description;
253 };
254 };
255
256 /* key data
257 * - this is used to hold the data actually used in cryptography or
258 * whatever
259 */
260 union {
261 union key_payload payload;
262 struct {
263 /* Keyring bits */
264 struct list_head name_link;
265 struct assoc_array keys;
266 };
267 };
268
269 /* This is set on a keyring to restrict the addition of a link to a key
270 * to it. If this structure isn't provided then it is assumed that the
271 * keyring is open to any addition. It is ignored for non-keyring
272 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
273 * or key_alloc().
274 *
275 * This is intended for use with rings of trusted keys whereby addition
276 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
277 * overrides this, allowing the kernel to add extra keys without
278 * restriction.
279 */
280 struct key_restriction *restrict_link;
281 };
282
283 extern struct key *key_alloc(struct key_type *type,
284 const char *desc,
285 kuid_t uid, kgid_t gid,
286 const struct cred *cred,
287 key_perm_t perm,
288 unsigned long flags,
289 struct key_restriction *restrict_link);
290
291
292 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
293 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
294 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
295 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
296 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
297 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
298 #define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
299
300 extern void key_revoke(struct key *key);
301 extern void key_invalidate(struct key *key);
302 extern void key_put(struct key *key);
303 extern bool key_put_tag(struct key_tag *tag);
304 extern void key_remove_domain(struct key_tag *domain_tag);
305
__key_get(struct key * key)306 static inline struct key *__key_get(struct key *key)
307 {
308 refcount_inc(&key->usage);
309 return key;
310 }
311
key_get(struct key * key)312 static inline struct key *key_get(struct key *key)
313 {
314 return key ? __key_get(key) : key;
315 }
316
key_ref_put(key_ref_t key_ref)317 static inline void key_ref_put(key_ref_t key_ref)
318 {
319 key_put(key_ref_to_ptr(key_ref));
320 }
321
322 extern struct key *request_key_tag(struct key_type *type,
323 const char *description,
324 struct key_tag *domain_tag,
325 const char *callout_info);
326
327 extern struct key *request_key_rcu(struct key_type *type,
328 const char *description,
329 struct key_tag *domain_tag);
330
331 extern struct key *request_key_with_auxdata(struct key_type *type,
332 const char *description,
333 struct key_tag *domain_tag,
334 const void *callout_info,
335 size_t callout_len,
336 void *aux);
337
338 /**
339 * request_key - Request a key and wait for construction
340 * @type: Type of key.
341 * @description: The searchable description of the key.
342 * @callout_info: The data to pass to the instantiation upcall (or NULL).
343 *
344 * As for request_key_tag(), but with the default global domain tag.
345 */
request_key(struct key_type * type,const char * description,const char * callout_info)346 static inline struct key *request_key(struct key_type *type,
347 const char *description,
348 const char *callout_info)
349 {
350 return request_key_tag(type, description, NULL, callout_info);
351 }
352
353 #ifdef CONFIG_NET
354 /**
355 * request_key_net - Request a key for a net namespace and wait for construction
356 * @type: Type of key.
357 * @description: The searchable description of the key.
358 * @net: The network namespace that is the key's domain of operation.
359 * @callout_info: The data to pass to the instantiation upcall (or NULL).
360 *
361 * As for request_key() except that it does not add the returned key to a
362 * keyring if found, new keys are always allocated in the user's quota, the
363 * callout_info must be a NUL-terminated string and no auxiliary data can be
364 * passed. Only keys that operate the specified network namespace are used.
365 *
366 * Furthermore, it then works as wait_for_key_construction() to wait for the
367 * completion of keys undergoing construction with a non-interruptible wait.
368 */
369 #define request_key_net(type, description, net, callout_info) \
370 request_key_tag(type, description, net->key_domain, callout_info)
371
372 /**
373 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
374 * @type: Type of key.
375 * @description: The searchable description of the key.
376 * @net: The network namespace that is the key's domain of operation.
377 *
378 * As for request_key_rcu() except that only keys that operate the specified
379 * network namespace are used.
380 */
381 #define request_key_net_rcu(type, description, net) \
382 request_key_rcu(type, description, net->key_domain)
383 #endif /* CONFIG_NET */
384
385 extern int wait_for_key_construction(struct key *key, bool intr);
386
387 extern int key_validate(const struct key *key);
388
389 extern key_ref_t key_create(key_ref_t keyring,
390 const char *type,
391 const char *description,
392 const void *payload,
393 size_t plen,
394 key_perm_t perm,
395 unsigned long flags);
396
397 extern key_ref_t key_create_or_update(key_ref_t keyring,
398 const char *type,
399 const char *description,
400 const void *payload,
401 size_t plen,
402 key_perm_t perm,
403 unsigned long flags);
404
405 extern int key_update(key_ref_t key,
406 const void *payload,
407 size_t plen);
408
409 extern int key_link(struct key *keyring,
410 struct key *key);
411
412 extern int key_move(struct key *key,
413 struct key *from_keyring,
414 struct key *to_keyring,
415 unsigned int flags);
416
417 extern int key_unlink(struct key *keyring,
418 struct key *key);
419
420 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
421 const struct cred *cred,
422 key_perm_t perm,
423 unsigned long flags,
424 struct key_restriction *restrict_link,
425 struct key *dest);
426
427 extern int restrict_link_reject(struct key *keyring,
428 const struct key_type *type,
429 const union key_payload *payload,
430 struct key *restriction_key);
431
432 extern int keyring_clear(struct key *keyring);
433
434 extern key_ref_t keyring_search(key_ref_t keyring,
435 struct key_type *type,
436 const char *description,
437 bool recurse);
438
439 extern int keyring_restrict(key_ref_t keyring, const char *type,
440 const char *restriction);
441
442 extern struct key *key_lookup(key_serial_t id);
443
key_serial(const struct key * key)444 static inline key_serial_t key_serial(const struct key *key)
445 {
446 return key ? key->serial : 0;
447 }
448
449 extern void key_set_timeout(struct key *, unsigned);
450
451 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
452 enum key_need_perm need_perm);
453 extern void key_free_user_ns(struct user_namespace *);
454
key_read_state(const struct key * key)455 static inline short key_read_state(const struct key *key)
456 {
457 /* Barrier versus mark_key_instantiated(). */
458 return smp_load_acquire(&key->state);
459 }
460
461 /**
462 * key_is_positive - Determine if a key has been positively instantiated
463 * @key: The key to check.
464 *
465 * Return true if the specified key has been positively instantiated, false
466 * otherwise.
467 */
key_is_positive(const struct key * key)468 static inline bool key_is_positive(const struct key *key)
469 {
470 return key_read_state(key) == KEY_IS_POSITIVE;
471 }
472
key_is_negative(const struct key * key)473 static inline bool key_is_negative(const struct key *key)
474 {
475 return key_read_state(key) < 0;
476 }
477
478 #define dereference_key_rcu(KEY) \
479 (rcu_dereference((KEY)->payload.rcu_data0))
480
481 #define dereference_key_locked(KEY) \
482 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
483 rwsem_is_locked(&((struct key *)(KEY))->sem)))
484
485 #define rcu_assign_keypointer(KEY, PAYLOAD) \
486 do { \
487 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
488 } while (0)
489
490 /*
491 * the userspace interface
492 */
493 extern int install_thread_keyring_to_cred(struct cred *cred);
494 extern void key_fsuid_changed(struct cred *new_cred);
495 extern void key_fsgid_changed(struct cred *new_cred);
496 extern void key_init(void);
497
498 #else /* CONFIG_KEYS */
499
500 #define key_validate(k) 0
501 #define key_serial(k) 0
502 #define key_get(k) ({ NULL; })
503 #define key_revoke(k) do { } while(0)
504 #define key_invalidate(k) do { } while(0)
505 #define key_put(k) do { } while(0)
506 #define key_ref_put(k) do { } while(0)
507 #define make_key_ref(k, p) NULL
508 #define key_ref_to_ptr(k) NULL
509 #define is_key_possessed(k) 0
510 #define key_fsuid_changed(c) do { } while(0)
511 #define key_fsgid_changed(c) do { } while(0)
512 #define key_init() do { } while(0)
513 #define key_free_user_ns(ns) do { } while(0)
514 #define key_remove_domain(d) do { } while(0)
515 #define key_lookup(k) NULL
516
517 #endif /* CONFIG_KEYS */
518 #endif /* __KERNEL__ */
519 #endif /* _LINUX_KEY_H */
520