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 struct seq_file;
92 struct user_struct;
93 struct signal_struct;
94 struct cred;
95
96 struct key_type;
97 struct key_owner;
98 struct key_tag;
99 struct keyring_list;
100 struct keyring_name;
101
102 struct key_tag {
103 struct rcu_head rcu;
104 refcount_t usage;
105 bool removed; /* T when subject removed */
106 };
107
108 struct keyring_index_key {
109 /* [!] If this structure is altered, the union in struct key must change too! */
110 unsigned long hash; /* Hash value */
111 union {
112 struct {
113 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
114 u16 desc_len;
115 char desc[sizeof(long) - 2]; /* First few chars of description */
116 #else
117 char desc[sizeof(long) - 2]; /* First few chars of description */
118 u16 desc_len;
119 #endif
120 };
121 unsigned long x;
122 };
123 struct key_type *type;
124 struct key_tag *domain_tag; /* Domain of operation */
125 const char *description;
126 };
127
128 union key_payload {
129 void __rcu *rcu_data0;
130 void *data[4];
131 };
132
133 /*****************************************************************************/
134 /*
135 * key reference with possession attribute handling
136 *
137 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
138 * defined. This is because we abuse the bottom bit of the reference to carry a
139 * flag to indicate whether the calling process possesses that key in one of
140 * its keyrings.
141 *
142 * the key_ref_t has been made a separate type so that the compiler can reject
143 * attempts to dereference it without proper conversion.
144 *
145 * the three functions are used to assemble and disassemble references
146 */
147 typedef struct __key_reference_with_attributes *key_ref_t;
148
make_key_ref(const struct key * key,bool possession)149 static inline key_ref_t make_key_ref(const struct key *key,
150 bool possession)
151 {
152 return (key_ref_t) ((unsigned long) key | possession);
153 }
154
key_ref_to_ptr(const key_ref_t key_ref)155 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
156 {
157 return (struct key *) ((unsigned long) key_ref & ~1UL);
158 }
159
is_key_possessed(const key_ref_t key_ref)160 static inline bool is_key_possessed(const key_ref_t key_ref)
161 {
162 return (unsigned long) key_ref & 1UL;
163 }
164
165 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
166 const struct key_type *type,
167 const union key_payload *payload,
168 struct key *restriction_key);
169
170 struct key_restriction {
171 key_restrict_link_func_t check;
172 struct key *key;
173 struct key_type *keytype;
174 };
175
176 enum key_state {
177 KEY_IS_UNINSTANTIATED,
178 KEY_IS_POSITIVE, /* Positively instantiated */
179 };
180
181 /*****************************************************************************/
182 /*
183 * authentication token / access credential / keyring
184 * - types of key include:
185 * - keyrings
186 * - disk encryption IDs
187 * - Kerberos TGTs and tickets
188 */
189 struct key {
190 refcount_t usage; /* number of references */
191 key_serial_t serial; /* key serial number */
192 union {
193 struct list_head graveyard_link;
194 struct rb_node serial_node;
195 };
196 #ifdef CONFIG_KEY_NOTIFICATIONS
197 struct watch_list *watchers; /* Entities watching this key for changes */
198 #endif
199 struct rw_semaphore sem; /* change vs change sem */
200 struct key_user *user; /* owner of this key */
201 void *security; /* security data for this key */
202 union {
203 time64_t expiry; /* time at which key expires (or 0) */
204 time64_t revoked_at; /* time at which key was revoked */
205 };
206 time64_t last_used_at; /* last time used for LRU keyring discard */
207 kuid_t uid;
208 kgid_t gid;
209 key_perm_t perm; /* access permissions */
210 unsigned short quotalen; /* length added to quota */
211 unsigned short datalen; /* payload data length
212 * - may not match RCU dereferenced payload
213 * - payload should contain own length
214 */
215 short state; /* Key state (+) or rejection error (-) */
216
217 #ifdef KEY_DEBUGGING
218 unsigned magic;
219 #define KEY_DEBUG_MAGIC 0x18273645u
220 #endif
221
222 unsigned long flags; /* status flags (change with bitops) */
223 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
224 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
225 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
226 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
227 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
228 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
229 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
230 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
231 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
232 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
233
234 /* the key type and key description string
235 * - the desc is used to match a key against search criteria
236 * - it should be a printable string
237 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
238 */
239 union {
240 struct keyring_index_key index_key;
241 struct {
242 unsigned long hash;
243 unsigned long len_desc;
244 struct key_type *type; /* type of key */
245 struct key_tag *domain_tag; /* Domain of operation */
246 char *description;
247 };
248 };
249
250 /* key data
251 * - this is used to hold the data actually used in cryptography or
252 * whatever
253 */
254 union {
255 union key_payload payload;
256 struct {
257 /* Keyring bits */
258 struct list_head name_link;
259 struct assoc_array keys;
260 };
261 };
262
263 /* This is set on a keyring to restrict the addition of a link to a key
264 * to it. If this structure isn't provided then it is assumed that the
265 * keyring is open to any addition. It is ignored for non-keyring
266 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
267 * or key_alloc().
268 *
269 * This is intended for use with rings of trusted keys whereby addition
270 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
271 * overrides this, allowing the kernel to add extra keys without
272 * restriction.
273 */
274 struct key_restriction *restrict_link;
275 };
276
277 extern struct key *key_alloc(struct key_type *type,
278 const char *desc,
279 kuid_t uid, kgid_t gid,
280 const struct cred *cred,
281 key_perm_t perm,
282 unsigned long flags,
283 struct key_restriction *restrict_link);
284
285
286 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
287 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
288 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
289 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
290 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
291 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
292
293 extern void key_revoke(struct key *key);
294 extern void key_invalidate(struct key *key);
295 extern void key_put(struct key *key);
296 extern bool key_put_tag(struct key_tag *tag);
297 extern void key_remove_domain(struct key_tag *domain_tag);
298
__key_get(struct key * key)299 static inline struct key *__key_get(struct key *key)
300 {
301 refcount_inc(&key->usage);
302 return key;
303 }
304
key_get(struct key * key)305 static inline struct key *key_get(struct key *key)
306 {
307 return key ? __key_get(key) : key;
308 }
309
key_ref_put(key_ref_t key_ref)310 static inline void key_ref_put(key_ref_t key_ref)
311 {
312 key_put(key_ref_to_ptr(key_ref));
313 }
314
315 extern struct key *request_key_tag(struct key_type *type,
316 const char *description,
317 struct key_tag *domain_tag,
318 const char *callout_info);
319
320 extern struct key *request_key_rcu(struct key_type *type,
321 const char *description,
322 struct key_tag *domain_tag);
323
324 extern struct key *request_key_with_auxdata(struct key_type *type,
325 const char *description,
326 struct key_tag *domain_tag,
327 const void *callout_info,
328 size_t callout_len,
329 void *aux);
330
331 /**
332 * request_key - Request a key and wait for construction
333 * @type: Type of key.
334 * @description: The searchable description of the key.
335 * @callout_info: The data to pass to the instantiation upcall (or NULL).
336 *
337 * As for request_key_tag(), but with the default global domain tag.
338 */
request_key(struct key_type * type,const char * description,const char * callout_info)339 static inline struct key *request_key(struct key_type *type,
340 const char *description,
341 const char *callout_info)
342 {
343 return request_key_tag(type, description, NULL, callout_info);
344 }
345
346 #ifdef CONFIG_NET
347 /**
348 * request_key_net - Request a key for a net namespace and wait for construction
349 * @type: Type of key.
350 * @description: The searchable description of the key.
351 * @net: The network namespace that is the key's domain of operation.
352 * @callout_info: The data to pass to the instantiation upcall (or NULL).
353 *
354 * As for request_key() except that it does not add the returned key to a
355 * keyring if found, new keys are always allocated in the user's quota, the
356 * callout_info must be a NUL-terminated string and no auxiliary data can be
357 * passed. Only keys that operate the specified network namespace are used.
358 *
359 * Furthermore, it then works as wait_for_key_construction() to wait for the
360 * completion of keys undergoing construction with a non-interruptible wait.
361 */
362 #define request_key_net(type, description, net, callout_info) \
363 request_key_tag(type, description, net->key_domain, callout_info);
364
365 /**
366 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
367 * @type: Type of key.
368 * @description: The searchable description of the key.
369 * @net: The network namespace that is the key's domain of operation.
370 *
371 * As for request_key_rcu() except that only keys that operate the specified
372 * network namespace are used.
373 */
374 #define request_key_net_rcu(type, description, net) \
375 request_key_rcu(type, description, net->key_domain);
376 #endif /* CONFIG_NET */
377
378 extern int wait_for_key_construction(struct key *key, bool intr);
379
380 extern int key_validate(const struct key *key);
381
382 extern key_ref_t key_create_or_update(key_ref_t keyring,
383 const char *type,
384 const char *description,
385 const void *payload,
386 size_t plen,
387 key_perm_t perm,
388 unsigned long flags);
389
390 extern int key_update(key_ref_t key,
391 const void *payload,
392 size_t plen);
393
394 extern int key_link(struct key *keyring,
395 struct key *key);
396
397 extern int key_move(struct key *key,
398 struct key *from_keyring,
399 struct key *to_keyring,
400 unsigned int flags);
401
402 extern int key_unlink(struct key *keyring,
403 struct key *key);
404
405 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
406 const struct cred *cred,
407 key_perm_t perm,
408 unsigned long flags,
409 struct key_restriction *restrict_link,
410 struct key *dest);
411
412 extern int restrict_link_reject(struct key *keyring,
413 const struct key_type *type,
414 const union key_payload *payload,
415 struct key *restriction_key);
416
417 extern int keyring_clear(struct key *keyring);
418
419 extern key_ref_t keyring_search(key_ref_t keyring,
420 struct key_type *type,
421 const char *description,
422 bool recurse);
423
424 extern int keyring_add_key(struct key *keyring,
425 struct key *key);
426
427 extern int keyring_restrict(key_ref_t keyring, const char *type,
428 const char *restriction);
429
430 extern struct key *key_lookup(key_serial_t id);
431
key_serial(const struct key * key)432 static inline key_serial_t key_serial(const struct key *key)
433 {
434 return key ? key->serial : 0;
435 }
436
437 extern void key_set_timeout(struct key *, unsigned);
438
439 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
440 enum key_need_perm need_perm);
441 extern void key_free_user_ns(struct user_namespace *);
442
key_read_state(const struct key * key)443 static inline short key_read_state(const struct key *key)
444 {
445 /* Barrier versus mark_key_instantiated(). */
446 return smp_load_acquire(&key->state);
447 }
448
449 /**
450 * key_is_positive - Determine if a key has been positively instantiated
451 * @key: The key to check.
452 *
453 * Return true if the specified key has been positively instantiated, false
454 * otherwise.
455 */
key_is_positive(const struct key * key)456 static inline bool key_is_positive(const struct key *key)
457 {
458 return key_read_state(key) == KEY_IS_POSITIVE;
459 }
460
key_is_negative(const struct key * key)461 static inline bool key_is_negative(const struct key *key)
462 {
463 return key_read_state(key) < 0;
464 }
465
466 #define dereference_key_rcu(KEY) \
467 (rcu_dereference((KEY)->payload.rcu_data0))
468
469 #define dereference_key_locked(KEY) \
470 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
471 rwsem_is_locked(&((struct key *)(KEY))->sem)))
472
473 #define rcu_assign_keypointer(KEY, PAYLOAD) \
474 do { \
475 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
476 } while (0)
477
478 #ifdef CONFIG_SYSCTL
479 extern struct ctl_table key_sysctls[];
480 #endif
481 /*
482 * the userspace interface
483 */
484 extern int install_thread_keyring_to_cred(struct cred *cred);
485 extern void key_fsuid_changed(struct cred *new_cred);
486 extern void key_fsgid_changed(struct cred *new_cred);
487 extern void key_init(void);
488
489 #else /* CONFIG_KEYS */
490
491 #define key_validate(k) 0
492 #define key_serial(k) 0
493 #define key_get(k) ({ NULL; })
494 #define key_revoke(k) do { } while(0)
495 #define key_invalidate(k) do { } while(0)
496 #define key_put(k) do { } while(0)
497 #define key_ref_put(k) do { } while(0)
498 #define make_key_ref(k, p) NULL
499 #define key_ref_to_ptr(k) NULL
500 #define is_key_possessed(k) 0
501 #define key_fsuid_changed(c) do { } while(0)
502 #define key_fsgid_changed(c) do { } while(0)
503 #define key_init() do { } while(0)
504 #define key_free_user_ns(ns) do { } while(0)
505 #define key_remove_domain(d) do { } while(0)
506
507 #endif /* CONFIG_KEYS */
508 #endif /* __KERNEL__ */
509 #endif /* _LINUX_KEY_H */
510
