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 */
28typedef int32_t key_serial_t;
29
30/* key handle permissions mask */
31typedef uint32_t key_perm_t;
32
33struct key;
34struct 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 */
77enum 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
91enum 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
97struct seq_file;
98struct user_struct;
99struct signal_struct;
100struct cred;
101
102struct key_type;
103struct key_owner;
104struct key_tag;
105struct keyring_list;
106struct keyring_name;
107
108struct key_tag {
109 struct rcu_head rcu;
110 refcount_t usage;
111 bool removed; /* T when subject removed */
112};
113
114struct 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
134union 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 */
153typedef struct __key_reference_with_attributes *key_ref_t;
154
155static 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
161static 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
166static inline bool is_key_possessed(const key_ref_t key_ref)
167{
168 return (unsigned long) key_ref & 1UL;
169}
170
171typedef 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
176struct key_restriction {
177 key_restrict_link_func_t check;
178 struct key *key;
179 struct key_type *keytype;
180};
181
182enum 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 */
195struct 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#define KEY_FLAG_FINAL_PUT 10 /* set if final put has happened on key */
240
241 /* the key type and key description string
242 * - the desc is used to match a key against search criteria
243 * - it should be a printable string
244 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
245 */
246 union {
247 struct keyring_index_key index_key;
248 struct {
249 unsigned long hash;
250 unsigned long len_desc;
251 struct key_type *type; /* type of key */
252 struct key_tag *domain_tag; /* Domain of operation */
253 char *description;
254 };
255 };
256
257 /* key data
258 * - this is used to hold the data actually used in cryptography or
259 * whatever
260 */
261 union {
262 union key_payload payload;
263 struct {
264 /* Keyring bits */
265 struct list_head name_link;
266 struct assoc_array keys;
267 };
268 };
269
270 /* This is set on a keyring to restrict the addition of a link to a key
271 * to it. If this structure isn't provided then it is assumed that the
272 * keyring is open to any addition. It is ignored for non-keyring
273 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
274 * or key_alloc().
275 *
276 * This is intended for use with rings of trusted keys whereby addition
277 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
278 * overrides this, allowing the kernel to add extra keys without
279 * restriction.
280 */
281 struct key_restriction *restrict_link;
282};
283
284extern struct key *key_alloc(struct key_type *type,
285 const char *desc,
286 kuid_t uid, kgid_t gid,
287 const struct cred *cred,
288 key_perm_t perm,
289 unsigned long flags,
290 struct key_restriction *restrict_link);
291
292
293#define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
294#define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
295#define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
296#define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
297#define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
298#define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
299#define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
300
301extern void key_revoke(struct key *key);
302extern void key_invalidate(struct key *key);
303extern void key_put(struct key *key);
304extern bool key_put_tag(struct key_tag *tag);
305extern void key_remove_domain(struct key_tag *domain_tag);
306
307static inline struct key *__key_get(struct key *key)
308{
309 refcount_inc(r: &key->usage);
310 return key;
311}
312
313static inline struct key *key_get(struct key *key)
314{
315 return key ? __key_get(key) : key;
316}
317
318static inline void key_ref_put(key_ref_t key_ref)
319{
320 key_put(key: key_ref_to_ptr(key_ref));
321}
322
323extern struct key *request_key_tag(struct key_type *type,
324 const char *description,
325 struct key_tag *domain_tag,
326 const char *callout_info);
327
328extern struct key *request_key_rcu(struct key_type *type,
329 const char *description,
330 struct key_tag *domain_tag);
331
332extern struct key *request_key_with_auxdata(struct key_type *type,
333 const char *description,
334 struct key_tag *domain_tag,
335 const void *callout_info,
336 size_t callout_len,
337 void *aux);
338
339/**
340 * request_key - Request a key and wait for construction
341 * @type: Type of key.
342 * @description: The searchable description of the key.
343 * @callout_info: The data to pass to the instantiation upcall (or NULL).
344 *
345 * As for request_key_tag(), but with the default global domain tag.
346 */
347static inline struct key *request_key(struct key_type *type,
348 const char *description,
349 const char *callout_info)
350{
351 return request_key_tag(type, description, NULL, callout_info);
352}
353
354#ifdef CONFIG_NET
355/**
356 * request_key_net - Request a key for a net namespace and wait for construction
357 * @type: Type of key.
358 * @description: The searchable description of the key.
359 * @net: The network namespace that is the key's domain of operation.
360 * @callout_info: The data to pass to the instantiation upcall (or NULL).
361 *
362 * As for request_key() except that it does not add the returned key to a
363 * keyring if found, new keys are always allocated in the user's quota, the
364 * callout_info must be a NUL-terminated string and no auxiliary data can be
365 * passed. Only keys that operate the specified network namespace are used.
366 *
367 * Furthermore, it then works as wait_for_key_construction() to wait for the
368 * completion of keys undergoing construction with a non-interruptible wait.
369 */
370#define request_key_net(type, description, net, callout_info) \
371 request_key_tag(type, description, net->key_domain, callout_info)
372
373/**
374 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
375 * @type: Type of key.
376 * @description: The searchable description of the key.
377 * @net: The network namespace that is the key's domain of operation.
378 *
379 * As for request_key_rcu() except that only keys that operate the specified
380 * network namespace are used.
381 */
382#define request_key_net_rcu(type, description, net) \
383 request_key_rcu(type, description, net->key_domain)
384#endif /* CONFIG_NET */
385
386extern int wait_for_key_construction(struct key *key, bool intr);
387
388extern int key_validate(const struct key *key);
389
390extern key_ref_t key_create(key_ref_t keyring,
391 const char *type,
392 const char *description,
393 const void *payload,
394 size_t plen,
395 key_perm_t perm,
396 unsigned long flags);
397
398extern key_ref_t key_create_or_update(key_ref_t keyring,
399 const char *type,
400 const char *description,
401 const void *payload,
402 size_t plen,
403 key_perm_t perm,
404 unsigned long flags);
405
406extern int key_update(key_ref_t key,
407 const void *payload,
408 size_t plen);
409
410extern int key_link(struct key *keyring,
411 struct key *key);
412
413extern int key_move(struct key *key,
414 struct key *from_keyring,
415 struct key *to_keyring,
416 unsigned int flags);
417
418extern int key_unlink(struct key *keyring,
419 struct key *key);
420
421extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
422 const struct cred *cred,
423 key_perm_t perm,
424 unsigned long flags,
425 struct key_restriction *restrict_link,
426 struct key *dest);
427
428extern int restrict_link_reject(struct key *keyring,
429 const struct key_type *type,
430 const union key_payload *payload,
431 struct key *restriction_key);
432
433extern int keyring_clear(struct key *keyring);
434
435extern key_ref_t keyring_search(key_ref_t keyring,
436 struct key_type *type,
437 const char *description,
438 bool recurse);
439
440extern int keyring_restrict(key_ref_t keyring, const char *type,
441 const char *restriction);
442
443extern struct key *key_lookup(key_serial_t id);
444
445static inline key_serial_t key_serial(const struct key *key)
446{
447 return key ? key->serial : 0;
448}
449
450extern void key_set_timeout(struct key *, unsigned);
451
452extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
453 enum key_need_perm need_perm);
454extern void key_free_user_ns(struct user_namespace *);
455
456static inline short key_read_state(const struct key *key)
457{
458 /* Barrier versus mark_key_instantiated(). */
459 return smp_load_acquire(&key->state);
460}
461
462/**
463 * key_is_positive - Determine if a key has been positively instantiated
464 * @key: The key to check.
465 *
466 * Return true if the specified key has been positively instantiated, false
467 * otherwise.
468 */
469static inline bool key_is_positive(const struct key *key)
470{
471 return key_read_state(key) == KEY_IS_POSITIVE;
472}
473
474static inline bool key_is_negative(const struct key *key)
475{
476 return key_read_state(key) < 0;
477}
478
479#define dereference_key_rcu(KEY) \
480 (rcu_dereference((KEY)->payload.rcu_data0))
481
482#define dereference_key_locked(KEY) \
483 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
484 rwsem_is_locked(&((struct key *)(KEY))->sem)))
485
486#define rcu_assign_keypointer(KEY, PAYLOAD) \
487do { \
488 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
489} while (0)
490
491/*
492 * the userspace interface
493 */
494extern int install_thread_keyring_to_cred(struct cred *cred);
495extern void key_fsuid_changed(struct cred *new_cred);
496extern void key_fsgid_changed(struct cred *new_cred);
497extern void key_init(void);
498
499#else /* CONFIG_KEYS */
500
501#define key_validate(k) 0
502#define key_serial(k) 0
503#define key_get(k) ({ NULL; })
504#define key_revoke(k) do { } while(0)
505#define key_invalidate(k) do { } while(0)
506#define key_put(k) do { } while(0)
507#define key_ref_put(k) do { } while(0)
508#define make_key_ref(k, p) NULL
509#define key_ref_to_ptr(k) NULL
510#define is_key_possessed(k) 0
511#define key_fsuid_changed(c) do { } while(0)
512#define key_fsgid_changed(c) do { } while(0)
513#define key_init() do { } while(0)
514#define key_free_user_ns(ns) do { } while(0)
515#define key_remove_domain(d) do { } while(0)
516#define key_lookup(k) NULL
517
518#endif /* CONFIG_KEYS */
519#endif /* __KERNEL__ */
520#endif /* _LINUX_KEY_H */
521

source code of linux/include/linux/key.h

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