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