1 /* Authentication token and access key management
2 *
3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 *
12 * See Documentation/security/keys/core.rst for information on keys/keyrings.
13 */
14
15 #ifndef _LINUX_KEY_H
16 #define _LINUX_KEY_H
17
18 #include <linux/types.h>
19 #include <linux/list.h>
20 #include <linux/rbtree.h>
21 #include <linux/rcupdate.h>
22 #include <linux/sysctl.h>
23 #include <linux/rwsem.h>
24 #include <linux/atomic.h>
25 #include <linux/assoc_array.h>
26 #include <linux/refcount.h>
27 #include <linux/time64.h>
28
29 #ifdef __KERNEL__
30 #include <linux/uidgid.h>
31
32 /* key handle serial number */
33 typedef int32_t key_serial_t;
34
35 /* key handle permissions mask */
36 typedef uint32_t key_perm_t;
37
38 struct key;
39
40 #ifdef CONFIG_KEYS
41
42 #undef KEY_DEBUGGING
43
44 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
45 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
46 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
47 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
48 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
49 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
50 #define KEY_POS_ALL 0x3f000000
51
52 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
53 #define KEY_USR_READ 0x00020000
54 #define KEY_USR_WRITE 0x00040000
55 #define KEY_USR_SEARCH 0x00080000
56 #define KEY_USR_LINK 0x00100000
57 #define KEY_USR_SETATTR 0x00200000
58 #define KEY_USR_ALL 0x003f0000
59
60 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
61 #define KEY_GRP_READ 0x00000200
62 #define KEY_GRP_WRITE 0x00000400
63 #define KEY_GRP_SEARCH 0x00000800
64 #define KEY_GRP_LINK 0x00001000
65 #define KEY_GRP_SETATTR 0x00002000
66 #define KEY_GRP_ALL 0x00003f00
67
68 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
69 #define KEY_OTH_READ 0x00000002
70 #define KEY_OTH_WRITE 0x00000004
71 #define KEY_OTH_SEARCH 0x00000008
72 #define KEY_OTH_LINK 0x00000010
73 #define KEY_OTH_SETATTR 0x00000020
74 #define KEY_OTH_ALL 0x0000003f
75
76 #define KEY_PERM_UNDEF 0xffffffff
77
78 struct seq_file;
79 struct user_struct;
80 struct signal_struct;
81 struct cred;
82
83 struct key_type;
84 struct key_owner;
85 struct keyring_list;
86 struct keyring_name;
87
88 struct keyring_index_key {
89 struct key_type *type;
90 const char *description;
91 size_t desc_len;
92 };
93
94 union key_payload {
95 void __rcu *rcu_data0;
96 void *data[4];
97 };
98
99 /*****************************************************************************/
100 /*
101 * key reference with possession attribute handling
102 *
103 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
104 * defined. This is because we abuse the bottom bit of the reference to carry a
105 * flag to indicate whether the calling process possesses that key in one of
106 * its keyrings.
107 *
108 * the key_ref_t has been made a separate type so that the compiler can reject
109 * attempts to dereference it without proper conversion.
110 *
111 * the three functions are used to assemble and disassemble references
112 */
113 typedef struct __key_reference_with_attributes *key_ref_t;
114
make_key_ref(const struct key * key,bool possession)115 static inline key_ref_t make_key_ref(const struct key *key,
116 bool possession)
117 {
118 return (key_ref_t) ((unsigned long) key | possession);
119 }
120
key_ref_to_ptr(const key_ref_t key_ref)121 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
122 {
123 return (struct key *) ((unsigned long) key_ref & ~1UL);
124 }
125
is_key_possessed(const key_ref_t key_ref)126 static inline bool is_key_possessed(const key_ref_t key_ref)
127 {
128 return (unsigned long) key_ref & 1UL;
129 }
130
131 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
132 const struct key_type *type,
133 const union key_payload *payload,
134 struct key *restriction_key);
135
136 struct key_restriction {
137 key_restrict_link_func_t check;
138 struct key *key;
139 struct key_type *keytype;
140 };
141
142 enum key_state {
143 KEY_IS_UNINSTANTIATED,
144 KEY_IS_POSITIVE, /* Positively instantiated */
145 };
146
147 /*****************************************************************************/
148 /*
149 * authentication token / access credential / keyring
150 * - types of key include:
151 * - keyrings
152 * - disk encryption IDs
153 * - Kerberos TGTs and tickets
154 */
155 struct key {
156 refcount_t usage; /* number of references */
157 key_serial_t serial; /* key serial number */
158 union {
159 struct list_head graveyard_link;
160 struct rb_node serial_node;
161 };
162 struct rw_semaphore sem; /* change vs change sem */
163 struct key_user *user; /* owner of this key */
164 void *security; /* security data for this key */
165 union {
166 time64_t expiry; /* time at which key expires (or 0) */
167 time64_t revoked_at; /* time at which key was revoked */
168 };
169 time64_t last_used_at; /* last time used for LRU keyring discard */
170 kuid_t uid;
171 kgid_t gid;
172 key_perm_t perm; /* access permissions */
173 unsigned short quotalen; /* length added to quota */
174 unsigned short datalen; /* payload data length
175 * - may not match RCU dereferenced payload
176 * - payload should contain own length
177 */
178 short state; /* Key state (+) or rejection error (-) */
179
180 #ifdef KEY_DEBUGGING
181 unsigned magic;
182 #define KEY_DEBUG_MAGIC 0x18273645u
183 #endif
184
185 unsigned long flags; /* status flags (change with bitops) */
186 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
187 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
188 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
189 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
190 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
191 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
192 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
193 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
194 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
195 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
196
197 /* the key type and key description string
198 * - the desc is used to match a key against search criteria
199 * - it should be a printable string
200 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
201 */
202 union {
203 struct keyring_index_key index_key;
204 struct {
205 struct key_type *type; /* type of key */
206 char *description;
207 };
208 };
209
210 /* key data
211 * - this is used to hold the data actually used in cryptography or
212 * whatever
213 */
214 union {
215 union key_payload payload;
216 struct {
217 /* Keyring bits */
218 struct list_head name_link;
219 struct assoc_array keys;
220 };
221 };
222
223 /* This is set on a keyring to restrict the addition of a link to a key
224 * to it. If this structure isn't provided then it is assumed that the
225 * keyring is open to any addition. It is ignored for non-keyring
226 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
227 * or key_alloc().
228 *
229 * This is intended for use with rings of trusted keys whereby addition
230 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
231 * overrides this, allowing the kernel to add extra keys without
232 * restriction.
233 */
234 struct key_restriction *restrict_link;
235 };
236
237 extern struct key *key_alloc(struct key_type *type,
238 const char *desc,
239 kuid_t uid, kgid_t gid,
240 const struct cred *cred,
241 key_perm_t perm,
242 unsigned long flags,
243 struct key_restriction *restrict_link);
244
245
246 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
247 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
248 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
249 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
250 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
251 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
252
253 extern void key_revoke(struct key *key);
254 extern void key_invalidate(struct key *key);
255 extern void key_put(struct key *key);
256
__key_get(struct key * key)257 static inline struct key *__key_get(struct key *key)
258 {
259 refcount_inc(&key->usage);
260 return key;
261 }
262
key_get(struct key * key)263 static inline struct key *key_get(struct key *key)
264 {
265 return key ? __key_get(key) : key;
266 }
267
key_ref_put(key_ref_t key_ref)268 static inline void key_ref_put(key_ref_t key_ref)
269 {
270 key_put(key_ref_to_ptr(key_ref));
271 }
272
273 extern struct key *request_key(struct key_type *type,
274 const char *description,
275 const char *callout_info);
276
277 extern struct key *request_key_with_auxdata(struct key_type *type,
278 const char *description,
279 const void *callout_info,
280 size_t callout_len,
281 void *aux);
282
283 extern struct key *request_key_async(struct key_type *type,
284 const char *description,
285 const void *callout_info,
286 size_t callout_len);
287
288 extern struct key *request_key_async_with_auxdata(struct key_type *type,
289 const char *description,
290 const void *callout_info,
291 size_t callout_len,
292 void *aux);
293
294 extern int wait_for_key_construction(struct key *key, bool intr);
295
296 extern int key_validate(const struct key *key);
297
298 extern key_ref_t key_create_or_update(key_ref_t keyring,
299 const char *type,
300 const char *description,
301 const void *payload,
302 size_t plen,
303 key_perm_t perm,
304 unsigned long flags);
305
306 extern int key_update(key_ref_t key,
307 const void *payload,
308 size_t plen);
309
310 extern int key_link(struct key *keyring,
311 struct key *key);
312
313 extern int key_unlink(struct key *keyring,
314 struct key *key);
315
316 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
317 const struct cred *cred,
318 key_perm_t perm,
319 unsigned long flags,
320 struct key_restriction *restrict_link,
321 struct key *dest);
322
323 extern int restrict_link_reject(struct key *keyring,
324 const struct key_type *type,
325 const union key_payload *payload,
326 struct key *restriction_key);
327
328 extern int keyring_clear(struct key *keyring);
329
330 extern key_ref_t keyring_search(key_ref_t keyring,
331 struct key_type *type,
332 const char *description);
333
334 extern int keyring_add_key(struct key *keyring,
335 struct key *key);
336
337 extern int keyring_restrict(key_ref_t keyring, const char *type,
338 const char *restriction);
339
340 extern struct key *key_lookup(key_serial_t id);
341
key_serial(const struct key * key)342 static inline key_serial_t key_serial(const struct key *key)
343 {
344 return key ? key->serial : 0;
345 }
346
347 extern void key_set_timeout(struct key *, unsigned);
348
349 /*
350 * The permissions required on a key that we're looking up.
351 */
352 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
353 #define KEY_NEED_READ 0x02 /* Require permission to read content */
354 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
355 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
356 #define KEY_NEED_LINK 0x10 /* Require permission to link */
357 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
358 #define KEY_NEED_ALL 0x3f /* All the above permissions */
359
key_read_state(const struct key * key)360 static inline short key_read_state(const struct key *key)
361 {
362 /* Barrier versus mark_key_instantiated(). */
363 return smp_load_acquire(&key->state);
364 }
365
366 /**
367 * key_is_positive - Determine if a key has been positively instantiated
368 * @key: The key to check.
369 *
370 * Return true if the specified key has been positively instantiated, false
371 * otherwise.
372 */
key_is_positive(const struct key * key)373 static inline bool key_is_positive(const struct key *key)
374 {
375 return key_read_state(key) == KEY_IS_POSITIVE;
376 }
377
key_is_negative(const struct key * key)378 static inline bool key_is_negative(const struct key *key)
379 {
380 return key_read_state(key) < 0;
381 }
382
383 #define dereference_key_rcu(KEY) \
384 (rcu_dereference((KEY)->payload.rcu_data0))
385
386 #define dereference_key_locked(KEY) \
387 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
388 rwsem_is_locked(&((struct key *)(KEY))->sem)))
389
390 #define rcu_assign_keypointer(KEY, PAYLOAD) \
391 do { \
392 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
393 } while (0)
394
395 #ifdef CONFIG_SYSCTL
396 extern struct ctl_table key_sysctls[];
397 #endif
398 /*
399 * the userspace interface
400 */
401 extern int install_thread_keyring_to_cred(struct cred *cred);
402 extern void key_fsuid_changed(struct task_struct *tsk);
403 extern void key_fsgid_changed(struct task_struct *tsk);
404 extern void key_init(void);
405
406 #else /* CONFIG_KEYS */
407
408 #define key_validate(k) 0
409 #define key_serial(k) 0
410 #define key_get(k) ({ NULL; })
411 #define key_revoke(k) do { } while(0)
412 #define key_invalidate(k) do { } while(0)
413 #define key_put(k) do { } while(0)
414 #define key_ref_put(k) do { } while(0)
415 #define make_key_ref(k, p) NULL
416 #define key_ref_to_ptr(k) NULL
417 #define is_key_possessed(k) 0
418 #define key_fsuid_changed(t) do { } while(0)
419 #define key_fsgid_changed(t) do { } while(0)
420 #define key_init() do { } while(0)
421
422 #endif /* CONFIG_KEYS */
423 #endif /* __KERNEL__ */
424 #endif /* _LINUX_KEY_H */
425
