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
91struct seq_file;
92struct user_struct;
93struct signal_struct;
94struct cred;
95
96struct key_type;
97struct key_owner;
98struct key_tag;
99struct keyring_list;
100struct keyring_name;
101
102struct key_tag {
103 struct rcu_head rcu;
104 refcount_t usage;
105 bool removed; /* T when subject removed */
106};
107
108struct 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
128union 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 */
147typedef struct __key_reference_with_attributes *key_ref_t;
148
149static 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
155static 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
160static inline bool is_key_possessed(const key_ref_t key_ref)
161{
162 return (unsigned long) key_ref & 1UL;
163}
164
165typedef 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
170struct key_restriction {
171 key_restrict_link_func_t check;
172 struct key *key;
173 struct key_type *keytype;
174};
175
176enum 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 */
189struct 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
277extern 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#define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
293
294extern void key_revoke(struct key *key);
295extern void key_invalidate(struct key *key);
296extern void key_put(struct key *key);
297extern bool key_put_tag(struct key_tag *tag);
298extern void key_remove_domain(struct key_tag *domain_tag);
299
300static inline struct key *__key_get(struct key *key)
301{
302 refcount_inc(&key->usage);
303 return key;
304}
305
306static inline struct key *key_get(struct key *key)
307{
308 return key ? __key_get(key) : key;
309}
310
311static inline void key_ref_put(key_ref_t key_ref)
312{
313 key_put(key_ref_to_ptr(key_ref));
314}
315
316extern struct key *request_key_tag(struct key_type *type,
317 const char *description,
318 struct key_tag *domain_tag,
319 const char *callout_info);
320
321extern struct key *request_key_rcu(struct key_type *type,
322 const char *description,
323 struct key_tag *domain_tag);
324
325extern struct key *request_key_with_auxdata(struct key_type *type,
326 const char *description,
327 struct key_tag *domain_tag,
328 const void *callout_info,
329 size_t callout_len,
330 void *aux);
331
332/**
333 * request_key - Request a key and wait for construction
334 * @type: Type of key.
335 * @description: The searchable description of the key.
336 * @callout_info: The data to pass to the instantiation upcall (or NULL).
337 *
338 * As for request_key_tag(), but with the default global domain tag.
339 */
340static inline struct key *request_key(struct key_type *type,
341 const char *description,
342 const char *callout_info)
343{
344 return request_key_tag(type, description, NULL, callout_info);
345}
346
347#ifdef CONFIG_NET
348/**
349 * request_key_net - Request a key for a net namespace and wait for construction
350 * @type: Type of key.
351 * @description: The searchable description of the key.
352 * @net: The network namespace that is the key's domain of operation.
353 * @callout_info: The data to pass to the instantiation upcall (or NULL).
354 *
355 * As for request_key() except that it does not add the returned key to a
356 * keyring if found, new keys are always allocated in the user's quota, the
357 * callout_info must be a NUL-terminated string and no auxiliary data can be
358 * passed. Only keys that operate the specified network namespace are used.
359 *
360 * Furthermore, it then works as wait_for_key_construction() to wait for the
361 * completion of keys undergoing construction with a non-interruptible wait.
362 */
363#define request_key_net(type, description, net, callout_info) \
364 request_key_tag(type, description, net->key_domain, callout_info)
365
366/**
367 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
368 * @type: Type of key.
369 * @description: The searchable description of the key.
370 * @net: The network namespace that is the key's domain of operation.
371 *
372 * As for request_key_rcu() except that only keys that operate the specified
373 * network namespace are used.
374 */
375#define request_key_net_rcu(type, description, net) \
376 request_key_rcu(type, description, net->key_domain)
377#endif /* CONFIG_NET */
378
379extern int wait_for_key_construction(struct key *key, bool intr);
380
381extern int key_validate(const struct key *key);
382
383extern key_ref_t key_create_or_update(key_ref_t keyring,
384 const char *type,
385 const char *description,
386 const void *payload,
387 size_t plen,
388 key_perm_t perm,
389 unsigned long flags);
390
391extern int key_update(key_ref_t key,
392 const void *payload,
393 size_t plen);
394
395extern int key_link(struct key *keyring,
396 struct key *key);
397
398extern int key_move(struct key *key,
399 struct key *from_keyring,
400 struct key *to_keyring,
401 unsigned int flags);
402
403extern int key_unlink(struct key *keyring,
404 struct key *key);
405
406extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
407 const struct cred *cred,
408 key_perm_t perm,
409 unsigned long flags,
410 struct key_restriction *restrict_link,
411 struct key *dest);
412
413extern int restrict_link_reject(struct key *keyring,
414 const struct key_type *type,
415 const union key_payload *payload,
416 struct key *restriction_key);
417
418extern int keyring_clear(struct key *keyring);
419
420extern key_ref_t keyring_search(key_ref_t keyring,
421 struct key_type *type,
422 const char *description,
423 bool recurse);
424
425extern int keyring_add_key(struct key *keyring,
426 struct key *key);
427
428extern int keyring_restrict(key_ref_t keyring, const char *type,
429 const char *restriction);
430
431extern struct key *key_lookup(key_serial_t id);
432
433static inline key_serial_t key_serial(const struct key *key)
434{
435 return key ? key->serial : 0;
436}
437
438extern void key_set_timeout(struct key *, unsigned);
439
440extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
441 enum key_need_perm need_perm);
442extern void key_free_user_ns(struct user_namespace *);
443
444static inline short key_read_state(const struct key *key)
445{
446 /* Barrier versus mark_key_instantiated(). */
447 return smp_load_acquire(&key->state);
448}
449
450/**
451 * key_is_positive - Determine if a key has been positively instantiated
452 * @key: The key to check.
453 *
454 * Return true if the specified key has been positively instantiated, false
455 * otherwise.
456 */
457static inline bool key_is_positive(const struct key *key)
458{
459 return key_read_state(key) == KEY_IS_POSITIVE;
460}
461
462static inline bool key_is_negative(const struct key *key)
463{
464 return key_read_state(key) < 0;
465}
466
467#define dereference_key_rcu(KEY) \
468 (rcu_dereference((KEY)->payload.rcu_data0))
469
470#define dereference_key_locked(KEY) \
471 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
472 rwsem_is_locked(&((struct key *)(KEY))->sem)))
473
474#define rcu_assign_keypointer(KEY, PAYLOAD) \
475do { \
476 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
477} while (0)
478
479#ifdef CONFIG_SYSCTL
480extern struct ctl_table key_sysctls[];
481#endif
482/*
483 * the userspace interface
484 */
485extern int install_thread_keyring_to_cred(struct cred *cred);
486extern void key_fsuid_changed(struct cred *new_cred);
487extern void key_fsgid_changed(struct cred *new_cred);
488extern void key_init(void);
489
490#else /* CONFIG_KEYS */
491
492#define key_validate(k) 0
493#define key_serial(k) 0
494#define key_get(k) ({ NULL; })
495#define key_revoke(k) do { } while(0)
496#define key_invalidate(k) do { } while(0)
497#define key_put(k) do { } while(0)
498#define key_ref_put(k) do { } while(0)
499#define make_key_ref(k, p) NULL
500#define key_ref_to_ptr(k) NULL
501#define is_key_possessed(k) 0
502#define key_fsuid_changed(c) do { } while(0)
503#define key_fsgid_changed(c) do { } while(0)
504#define key_init() do { } while(0)
505#define key_free_user_ns(ns) do { } while(0)
506#define key_remove_domain(d) do { } while(0)
507
508#endif /* CONFIG_KEYS */
509#endif /* __KERNEL__ */
510#endif /* _LINUX_KEY_H */
511

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