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
273 extern void key_revoke(struct key *key);
274 extern void key_invalidate(struct key *key);
275 extern void key_put(struct key *key);
276 extern bool key_put_tag(struct key_tag *tag);
277 extern void key_remove_domain(struct key_tag *domain_tag);
278
__key_get(struct key * key)279 static inline struct key *__key_get(struct key *key)
280 {
281 refcount_inc(&key->usage);
282 return key;
283 }
284
key_get(struct key * key)285 static inline struct key *key_get(struct key *key)
286 {
287 return key ? __key_get(key) : key;
288 }
289
key_ref_put(key_ref_t key_ref)290 static inline void key_ref_put(key_ref_t key_ref)
291 {
292 key_put(key_ref_to_ptr(key_ref));
293 }
294
295 extern struct key *request_key_tag(struct key_type *type,
296 const char *description,
297 struct key_tag *domain_tag,
298 const char *callout_info);
299
300 extern struct key *request_key_rcu(struct key_type *type,
301 const char *description,
302 struct key_tag *domain_tag);
303
304 extern struct key *request_key_with_auxdata(struct key_type *type,
305 const char *description,
306 struct key_tag *domain_tag,
307 const void *callout_info,
308 size_t callout_len,
309 void *aux);
310
311 /**
312 * request_key - Request a key and wait for construction
313 * @type: Type of key.
314 * @description: The searchable description of the key.
315 * @callout_info: The data to pass to the instantiation upcall (or NULL).
316 *
317 * As for request_key_tag(), but with the default global domain tag.
318 */
request_key(struct key_type * type,const char * description,const char * callout_info)319 static inline struct key *request_key(struct key_type *type,
320 const char *description,
321 const char *callout_info)
322 {
323 return request_key_tag(type, description, NULL, callout_info);
324 }
325
326 #ifdef CONFIG_NET
327 /**
328 * request_key_net - Request a key for a net namespace and wait for construction
329 * @type: Type of key.
330 * @description: The searchable description of the key.
331 * @net: The network namespace that is the key's domain of operation.
332 * @callout_info: The data to pass to the instantiation upcall (or NULL).
333 *
334 * As for request_key() except that it does not add the returned key to a
335 * keyring if found, new keys are always allocated in the user's quota, the
336 * callout_info must be a NUL-terminated string and no auxiliary data can be
337 * passed. Only keys that operate the specified network namespace are used.
338 *
339 * Furthermore, it then works as wait_for_key_construction() to wait for the
340 * completion of keys undergoing construction with a non-interruptible wait.
341 */
342 #define request_key_net(type, description, net, callout_info) \
343 request_key_tag(type, description, net->key_domain, callout_info);
344
345 /**
346 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
347 * @type: Type of key.
348 * @description: The searchable description of the key.
349 * @net: The network namespace that is the key's domain of operation.
350 *
351 * As for request_key_rcu() except that only keys that operate the specified
352 * network namespace are used.
353 */
354 #define request_key_net_rcu(type, description, net) \
355 request_key_rcu(type, description, net->key_domain);
356 #endif /* CONFIG_NET */
357
358 extern int wait_for_key_construction(struct key *key, bool intr);
359
360 extern int key_validate(const struct key *key);
361
362 extern key_ref_t key_create_or_update(key_ref_t keyring,
363 const char *type,
364 const char *description,
365 const void *payload,
366 size_t plen,
367 key_perm_t perm,
368 unsigned long flags);
369
370 extern int key_update(key_ref_t key,
371 const void *payload,
372 size_t plen);
373
374 extern int key_link(struct key *keyring,
375 struct key *key);
376
377 extern int key_move(struct key *key,
378 struct key *from_keyring,
379 struct key *to_keyring,
380 unsigned int flags);
381
382 extern int key_unlink(struct key *keyring,
383 struct key *key);
384
385 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
386 const struct cred *cred,
387 key_perm_t perm,
388 unsigned long flags,
389 struct key_restriction *restrict_link,
390 struct key *dest);
391
392 extern int restrict_link_reject(struct key *keyring,
393 const struct key_type *type,
394 const union key_payload *payload,
395 struct key *restriction_key);
396
397 extern int keyring_clear(struct key *keyring);
398
399 extern key_ref_t keyring_search(key_ref_t keyring,
400 struct key_type *type,
401 const char *description,
402 bool recurse);
403
404 extern int keyring_add_key(struct key *keyring,
405 struct key *key);
406
407 extern int keyring_restrict(key_ref_t keyring, const char *type,
408 const char *restriction);
409
410 extern struct key *key_lookup(key_serial_t id);
411
key_serial(const struct key * key)412 static inline key_serial_t key_serial(const struct key *key)
413 {
414 return key ? key->serial : 0;
415 }
416
417 extern void key_set_timeout(struct key *, unsigned);
418
419 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
420 key_perm_t perm);
421 extern void key_free_user_ns(struct user_namespace *);
422
423 /*
424 * The permissions required on a key that we're looking up.
425 */
426 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
427 #define KEY_NEED_READ 0x02 /* Require permission to read content */
428 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
429 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
430 #define KEY_NEED_LINK 0x10 /* Require permission to link */
431 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
432 #define KEY_NEED_ALL 0x3f /* All the above permissions */
433
key_read_state(const struct key * key)434 static inline short key_read_state(const struct key *key)
435 {
436 /* Barrier versus mark_key_instantiated(). */
437 return smp_load_acquire(&key->state);
438 }
439
440 /**
441 * key_is_positive - Determine if a key has been positively instantiated
442 * @key: The key to check.
443 *
444 * Return true if the specified key has been positively instantiated, false
445 * otherwise.
446 */
key_is_positive(const struct key * key)447 static inline bool key_is_positive(const struct key *key)
448 {
449 return key_read_state(key) == KEY_IS_POSITIVE;
450 }
451
key_is_negative(const struct key * key)452 static inline bool key_is_negative(const struct key *key)
453 {
454 return key_read_state(key) < 0;
455 }
456
457 #define dereference_key_rcu(KEY) \
458 (rcu_dereference((KEY)->payload.rcu_data0))
459
460 #define dereference_key_locked(KEY) \
461 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
462 rwsem_is_locked(&((struct key *)(KEY))->sem)))
463
464 #define rcu_assign_keypointer(KEY, PAYLOAD) \
465 do { \
466 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
467 } while (0)
468
469 #ifdef CONFIG_SYSCTL
470 extern struct ctl_table key_sysctls[];
471 #endif
472 /*
473 * the userspace interface
474 */
475 extern int install_thread_keyring_to_cred(struct cred *cred);
476 extern void key_fsuid_changed(struct cred *new_cred);
477 extern void key_fsgid_changed(struct cred *new_cred);
478 extern void key_init(void);
479
480 #else /* CONFIG_KEYS */
481
482 #define key_validate(k) 0
483 #define key_serial(k) 0
484 #define key_get(k) ({ NULL; })
485 #define key_revoke(k) do { } while(0)
486 #define key_invalidate(k) do { } while(0)
487 #define key_put(k) do { } while(0)
488 #define key_ref_put(k) do { } while(0)
489 #define make_key_ref(k, p) NULL
490 #define key_ref_to_ptr(k) NULL
491 #define is_key_possessed(k) 0
492 #define key_fsuid_changed(c) do { } while(0)
493 #define key_fsgid_changed(c) do { } while(0)
494 #define key_init() do { } while(0)
495 #define key_free_user_ns(ns) do { } while(0)
496 #define key_remove_domain(d) do { } while(0)
497
498 #endif /* CONFIG_KEYS */
499 #endif /* __KERNEL__ */
500 #endif /* _LINUX_KEY_H */
501
