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 struct seq_file;
75 struct user_struct;
76 struct signal_struct;
77 struct cred;
78
79 struct key_type;
80 struct key_owner;
81 struct key_tag;
82 struct keyring_list;
83 struct keyring_name;
84
85 struct key_tag {
86 struct rcu_head rcu;
87 refcount_t usage;
88 bool removed; /* T when subject removed */
89 };
90
91 struct keyring_index_key {
92 /* [!] If this structure is altered, the union in struct key must change too! */
93 unsigned long hash; /* Hash value */
94 union {
95 struct {
96 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
97 u16 desc_len;
98 char desc[sizeof(long) - 2]; /* First few chars of description */
99 #else
100 char desc[sizeof(long) - 2]; /* First few chars of description */
101 u16 desc_len;
102 #endif
103 };
104 unsigned long x;
105 };
106 struct key_type *type;
107 struct key_tag *domain_tag; /* Domain of operation */
108 const char *description;
109 };
110
111 union key_payload {
112 void __rcu *rcu_data0;
113 void *data[4];
114 };
115
116 /*****************************************************************************/
117 /*
118 * key reference with possession attribute handling
119 *
120 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
121 * defined. This is because we abuse the bottom bit of the reference to carry a
122 * flag to indicate whether the calling process possesses that key in one of
123 * its keyrings.
124 *
125 * the key_ref_t has been made a separate type so that the compiler can reject
126 * attempts to dereference it without proper conversion.
127 *
128 * the three functions are used to assemble and disassemble references
129 */
130 typedef struct __key_reference_with_attributes *key_ref_t;
131
make_key_ref(const struct key * key,bool possession)132 static inline key_ref_t make_key_ref(const struct key *key,
133 bool possession)
134 {
135 return (key_ref_t) ((unsigned long) key | possession);
136 }
137
key_ref_to_ptr(const key_ref_t key_ref)138 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
139 {
140 return (struct key *) ((unsigned long) key_ref & ~1UL);
141 }
142
is_key_possessed(const key_ref_t key_ref)143 static inline bool is_key_possessed(const key_ref_t key_ref)
144 {
145 return (unsigned long) key_ref & 1UL;
146 }
147
148 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
149 const struct key_type *type,
150 const union key_payload *payload,
151 struct key *restriction_key);
152
153 struct key_restriction {
154 key_restrict_link_func_t check;
155 struct key *key;
156 struct key_type *keytype;
157 };
158
159 enum key_state {
160 KEY_IS_UNINSTANTIATED,
161 KEY_IS_POSITIVE, /* Positively instantiated */
162 };
163
164 /*****************************************************************************/
165 /*
166 * authentication token / access credential / keyring
167 * - types of key include:
168 * - keyrings
169 * - disk encryption IDs
170 * - Kerberos TGTs and tickets
171 */
172 struct key {
173 refcount_t usage; /* number of references */
174 key_serial_t serial; /* key serial number */
175 union {
176 struct list_head graveyard_link;
177 struct rb_node serial_node;
178 };
179 struct rw_semaphore sem; /* change vs change sem */
180 struct key_user *user; /* owner of this key */
181 void *security; /* security data for this key */
182 union {
183 time64_t expiry; /* time at which key expires (or 0) */
184 time64_t revoked_at; /* time at which key was revoked */
185 };
186 time64_t last_used_at; /* last time used for LRU keyring discard */
187 kuid_t uid;
188 kgid_t gid;
189 key_perm_t perm; /* access permissions */
190 unsigned short quotalen; /* length added to quota */
191 unsigned short datalen; /* payload data length
192 * - may not match RCU dereferenced payload
193 * - payload should contain own length
194 */
195 short state; /* Key state (+) or rejection error (-) */
196
197 #ifdef KEY_DEBUGGING
198 unsigned magic;
199 #define KEY_DEBUG_MAGIC 0x18273645u
200 #endif
201
202 unsigned long flags; /* status flags (change with bitops) */
203 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
204 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
205 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
206 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
207 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
208 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
209 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
210 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
211 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
212 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
213
214 /* the key type and key description string
215 * - the desc is used to match a key against search criteria
216 * - it should be a printable string
217 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
218 */
219 union {
220 struct keyring_index_key index_key;
221 struct {
222 unsigned long hash;
223 unsigned long len_desc;
224 struct key_type *type; /* type of key */
225 struct key_tag *domain_tag; /* Domain of operation */
226 char *description;
227 };
228 };
229
230 /* key data
231 * - this is used to hold the data actually used in cryptography or
232 * whatever
233 */
234 union {
235 union key_payload payload;
236 struct {
237 /* Keyring bits */
238 struct list_head name_link;
239 struct assoc_array keys;
240 };
241 };
242
243 /* This is set on a keyring to restrict the addition of a link to a key
244 * to it. If this structure isn't provided then it is assumed that the
245 * keyring is open to any addition. It is ignored for non-keyring
246 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
247 * or key_alloc().
248 *
249 * This is intended for use with rings of trusted keys whereby addition
250 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
251 * overrides this, allowing the kernel to add extra keys without
252 * restriction.
253 */
254 struct key_restriction *restrict_link;
255 };
256
257 extern struct key *key_alloc(struct key_type *type,
258 const char *desc,
259 kuid_t uid, kgid_t gid,
260 const struct cred *cred,
261 key_perm_t perm,
262 unsigned long flags,
263 struct key_restriction *restrict_link);
264
265
266 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
267 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
268 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
269 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
270 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
271 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
272 #define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
273
274 extern void key_revoke(struct key *key);
275 extern void key_invalidate(struct key *key);
276 extern void key_put(struct key *key);
277 extern bool key_put_tag(struct key_tag *tag);
278 extern void key_remove_domain(struct key_tag *domain_tag);
279
__key_get(struct key * key)280 static inline struct key *__key_get(struct key *key)
281 {
282 refcount_inc(&key->usage);
283 return key;
284 }
285
key_get(struct key * key)286 static inline struct key *key_get(struct key *key)
287 {
288 return key ? __key_get(key) : key;
289 }
290
key_ref_put(key_ref_t key_ref)291 static inline void key_ref_put(key_ref_t key_ref)
292 {
293 key_put(key_ref_to_ptr(key_ref));
294 }
295
296 extern struct key *request_key_tag(struct key_type *type,
297 const char *description,
298 struct key_tag *domain_tag,
299 const char *callout_info);
300
301 extern struct key *request_key_rcu(struct key_type *type,
302 const char *description,
303 struct key_tag *domain_tag);
304
305 extern struct key *request_key_with_auxdata(struct key_type *type,
306 const char *description,
307 struct key_tag *domain_tag,
308 const void *callout_info,
309 size_t callout_len,
310 void *aux);
311
312 /**
313 * request_key - Request a key and wait for construction
314 * @type: Type of key.
315 * @description: The searchable description of the key.
316 * @callout_info: The data to pass to the instantiation upcall (or NULL).
317 *
318 * As for request_key_tag(), but with the default global domain tag.
319 */
request_key(struct key_type * type,const char * description,const char * callout_info)320 static inline struct key *request_key(struct key_type *type,
321 const char *description,
322 const char *callout_info)
323 {
324 return request_key_tag(type, description, NULL, callout_info);
325 }
326
327 #ifdef CONFIG_NET
328 /**
329 * request_key_net - Request a key for a net namespace and wait for construction
330 * @type: Type of key.
331 * @description: The searchable description of the key.
332 * @net: The network namespace that is the key's domain of operation.
333 * @callout_info: The data to pass to the instantiation upcall (or NULL).
334 *
335 * As for request_key() except that it does not add the returned key to a
336 * keyring if found, new keys are always allocated in the user's quota, the
337 * callout_info must be a NUL-terminated string and no auxiliary data can be
338 * passed. Only keys that operate the specified network namespace are used.
339 *
340 * Furthermore, it then works as wait_for_key_construction() to wait for the
341 * completion of keys undergoing construction with a non-interruptible wait.
342 */
343 #define request_key_net(type, description, net, callout_info) \
344 request_key_tag(type, description, net->key_domain, callout_info);
345
346 /**
347 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
348 * @type: Type of key.
349 * @description: The searchable description of the key.
350 * @net: The network namespace that is the key's domain of operation.
351 *
352 * As for request_key_rcu() except that only keys that operate the specified
353 * network namespace are used.
354 */
355 #define request_key_net_rcu(type, description, net) \
356 request_key_rcu(type, description, net->key_domain);
357 #endif /* CONFIG_NET */
358
359 extern int wait_for_key_construction(struct key *key, bool intr);
360
361 extern int key_validate(const struct key *key);
362
363 extern key_ref_t key_create_or_update(key_ref_t keyring,
364 const char *type,
365 const char *description,
366 const void *payload,
367 size_t plen,
368 key_perm_t perm,
369 unsigned long flags);
370
371 extern int key_update(key_ref_t key,
372 const void *payload,
373 size_t plen);
374
375 extern int key_link(struct key *keyring,
376 struct key *key);
377
378 extern int key_move(struct key *key,
379 struct key *from_keyring,
380 struct key *to_keyring,
381 unsigned int flags);
382
383 extern int key_unlink(struct key *keyring,
384 struct key *key);
385
386 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
387 const struct cred *cred,
388 key_perm_t perm,
389 unsigned long flags,
390 struct key_restriction *restrict_link,
391 struct key *dest);
392
393 extern int restrict_link_reject(struct key *keyring,
394 const struct key_type *type,
395 const union key_payload *payload,
396 struct key *restriction_key);
397
398 extern int keyring_clear(struct key *keyring);
399
400 extern key_ref_t keyring_search(key_ref_t keyring,
401 struct key_type *type,
402 const char *description,
403 bool recurse);
404
405 extern int keyring_add_key(struct key *keyring,
406 struct key *key);
407
408 extern int keyring_restrict(key_ref_t keyring, const char *type,
409 const char *restriction);
410
411 extern struct key *key_lookup(key_serial_t id);
412
key_serial(const struct key * key)413 static inline key_serial_t key_serial(const struct key *key)
414 {
415 return key ? key->serial : 0;
416 }
417
418 extern void key_set_timeout(struct key *, unsigned);
419
420 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
421 key_perm_t perm);
422 extern void key_free_user_ns(struct user_namespace *);
423
424 /*
425 * The permissions required on a key that we're looking up.
426 */
427 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
428 #define KEY_NEED_READ 0x02 /* Require permission to read content */
429 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
430 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
431 #define KEY_NEED_LINK 0x10 /* Require permission to link */
432 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
433 #define KEY_NEED_ALL 0x3f /* All the above permissions */
434
key_read_state(const struct key * key)435 static inline short key_read_state(const struct key *key)
436 {
437 /* Barrier versus mark_key_instantiated(). */
438 return smp_load_acquire(&key->state);
439 }
440
441 /**
442 * key_is_positive - Determine if a key has been positively instantiated
443 * @key: The key to check.
444 *
445 * Return true if the specified key has been positively instantiated, false
446 * otherwise.
447 */
key_is_positive(const struct key * key)448 static inline bool key_is_positive(const struct key *key)
449 {
450 return key_read_state(key) == KEY_IS_POSITIVE;
451 }
452
key_is_negative(const struct key * key)453 static inline bool key_is_negative(const struct key *key)
454 {
455 return key_read_state(key) < 0;
456 }
457
458 #define dereference_key_rcu(KEY) \
459 (rcu_dereference((KEY)->payload.rcu_data0))
460
461 #define dereference_key_locked(KEY) \
462 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
463 rwsem_is_locked(&((struct key *)(KEY))->sem)))
464
465 #define rcu_assign_keypointer(KEY, PAYLOAD) \
466 do { \
467 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
468 } while (0)
469
470 #ifdef CONFIG_SYSCTL
471 extern struct ctl_table key_sysctls[];
472 #endif
473 /*
474 * the userspace interface
475 */
476 extern int install_thread_keyring_to_cred(struct cred *cred);
477 extern void key_fsuid_changed(struct cred *new_cred);
478 extern void key_fsgid_changed(struct cred *new_cred);
479 extern void key_init(void);
480
481 #else /* CONFIG_KEYS */
482
483 #define key_validate(k) 0
484 #define key_serial(k) 0
485 #define key_get(k) ({ NULL; })
486 #define key_revoke(k) do { } while(0)
487 #define key_invalidate(k) do { } while(0)
488 #define key_put(k) do { } while(0)
489 #define key_ref_put(k) do { } while(0)
490 #define make_key_ref(k, p) NULL
491 #define key_ref_to_ptr(k) NULL
492 #define is_key_possessed(k) 0
493 #define key_fsuid_changed(c) do { } while(0)
494 #define key_fsgid_changed(c) do { } while(0)
495 #define key_init() do { } while(0)
496 #define key_free_user_ns(ns) do { } while(0)
497 #define key_remove_domain(d) do { } while(0)
498
499 #endif /* CONFIG_KEYS */
500 #endif /* __KERNEL__ */
501 #endif /* _LINUX_KEY_H */
502