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.txt 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
27 #ifdef __KERNEL__
28 #include <linux/uidgid.h>
29
30 /* key handle serial number */
31 typedef int32_t key_serial_t;
32
33 /* key handle permissions mask */
34 typedef uint32_t key_perm_t;
35
36 struct key;
37
38 #ifdef CONFIG_KEYS
39
40 #undef KEY_DEBUGGING
41
42 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
43 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
44 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
45 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
46 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
47 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
48 #define KEY_POS_ALL 0x3f000000
49
50 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
51 #define KEY_USR_READ 0x00020000
52 #define KEY_USR_WRITE 0x00040000
53 #define KEY_USR_SEARCH 0x00080000
54 #define KEY_USR_LINK 0x00100000
55 #define KEY_USR_SETATTR 0x00200000
56 #define KEY_USR_ALL 0x003f0000
57
58 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
59 #define KEY_GRP_READ 0x00000200
60 #define KEY_GRP_WRITE 0x00000400
61 #define KEY_GRP_SEARCH 0x00000800
62 #define KEY_GRP_LINK 0x00001000
63 #define KEY_GRP_SETATTR 0x00002000
64 #define KEY_GRP_ALL 0x00003f00
65
66 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
67 #define KEY_OTH_READ 0x00000002
68 #define KEY_OTH_WRITE 0x00000004
69 #define KEY_OTH_SEARCH 0x00000008
70 #define KEY_OTH_LINK 0x00000010
71 #define KEY_OTH_SETATTR 0x00000020
72 #define KEY_OTH_ALL 0x0000003f
73
74 #define KEY_PERM_UNDEF 0xffffffff
75
76 struct seq_file;
77 struct user_struct;
78 struct signal_struct;
79 struct cred;
80
81 struct key_type;
82 struct key_owner;
83 struct keyring_list;
84 struct keyring_name;
85
86 struct keyring_index_key {
87 struct key_type *type;
88 const char *description;
89 size_t desc_len;
90 };
91
92 union key_payload {
93 void __rcu *rcu_data0;
94 void *data[4];
95 };
96
97 /*****************************************************************************/
98 /*
99 * key reference with possession attribute handling
100 *
101 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
102 * defined. This is because we abuse the bottom bit of the reference to carry a
103 * flag to indicate whether the calling process possesses that key in one of
104 * its keyrings.
105 *
106 * the key_ref_t has been made a separate type so that the compiler can reject
107 * attempts to dereference it without proper conversion.
108 *
109 * the three functions are used to assemble and disassemble references
110 */
111 typedef struct __key_reference_with_attributes *key_ref_t;
112
make_key_ref(const struct key * key,bool possession)113 static inline key_ref_t make_key_ref(const struct key *key,
114 bool possession)
115 {
116 return (key_ref_t) ((unsigned long) key | possession);
117 }
118
key_ref_to_ptr(const key_ref_t key_ref)119 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
120 {
121 return (struct key *) ((unsigned long) key_ref & ~1UL);
122 }
123
is_key_possessed(const key_ref_t key_ref)124 static inline bool is_key_possessed(const key_ref_t key_ref)
125 {
126 return (unsigned long) key_ref & 1UL;
127 }
128
129 enum key_state {
130 KEY_IS_UNINSTANTIATED,
131 KEY_IS_POSITIVE, /* Positively instantiated */
132 };
133
134 /*****************************************************************************/
135 /*
136 * authentication token / access credential / keyring
137 * - types of key include:
138 * - keyrings
139 * - disk encryption IDs
140 * - Kerberos TGTs and tickets
141 */
142 struct key {
143 atomic_t usage; /* number of references */
144 key_serial_t serial; /* key serial number */
145 union {
146 struct list_head graveyard_link;
147 struct rb_node serial_node;
148 };
149 struct rw_semaphore sem; /* change vs change sem */
150 struct key_user *user; /* owner of this key */
151 void *security; /* security data for this key */
152 union {
153 time_t expiry; /* time at which key expires (or 0) */
154 time_t revoked_at; /* time at which key was revoked */
155 };
156 time_t last_used_at; /* last time used for LRU keyring discard */
157 kuid_t uid;
158 kgid_t gid;
159 key_perm_t perm; /* access permissions */
160 unsigned short quotalen; /* length added to quota */
161 unsigned short datalen; /* payload data length
162 * - may not match RCU dereferenced payload
163 * - payload should contain own length
164 */
165 short state; /* Key state (+) or rejection error (-) */
166
167 #ifdef KEY_DEBUGGING
168 unsigned magic;
169 #define KEY_DEBUG_MAGIC 0x18273645u
170 #define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
171 #endif
172
173 unsigned long flags; /* status flags (change with bitops) */
174 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
175 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
176 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
177 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
178 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
179 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
180 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
181 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
182 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
183 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
184
185 /* the key type and key description string
186 * - the desc is used to match a key against search criteria
187 * - it should be a printable string
188 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
189 */
190 union {
191 struct keyring_index_key index_key;
192 struct {
193 struct key_type *type; /* type of key */
194 char *description;
195 };
196 };
197
198 /* key data
199 * - this is used to hold the data actually used in cryptography or
200 * whatever
201 */
202 union {
203 union key_payload payload;
204 struct {
205 /* Keyring bits */
206 struct list_head name_link;
207 struct assoc_array keys;
208 };
209 };
210
211 /* This is set on a keyring to restrict the addition of a link to a key
212 * to it. If this method isn't provided then it is assumed that the
213 * keyring is open to any addition. It is ignored for non-keyring
214 * keys.
215 *
216 * This is intended for use with rings of trusted keys whereby addition
217 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
218 * overrides this, allowing the kernel to add extra keys without
219 * restriction.
220 */
221 int (*restrict_link)(struct key *keyring,
222 const struct key_type *type,
223 const union key_payload *payload);
224 };
225
226 extern struct key *key_alloc(struct key_type *type,
227 const char *desc,
228 kuid_t uid, kgid_t gid,
229 const struct cred *cred,
230 key_perm_t perm,
231 unsigned long flags,
232 int (*restrict_link)(struct key *,
233 const struct key_type *,
234 const union key_payload *));
235
236
237 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
238 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
239 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
240 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
241 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
242 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
243
244 extern void key_revoke(struct key *key);
245 extern void key_invalidate(struct key *key);
246 extern void key_put(struct key *key);
247
__key_get(struct key * key)248 static inline struct key *__key_get(struct key *key)
249 {
250 atomic_inc(&key->usage);
251 return key;
252 }
253
key_get(struct key * key)254 static inline struct key *key_get(struct key *key)
255 {
256 return key ? __key_get(key) : key;
257 }
258
key_ref_put(key_ref_t key_ref)259 static inline void key_ref_put(key_ref_t key_ref)
260 {
261 key_put(key_ref_to_ptr(key_ref));
262 }
263
264 extern struct key *request_key(struct key_type *type,
265 const char *description,
266 const char *callout_info);
267
268 extern struct key *request_key_with_auxdata(struct key_type *type,
269 const char *description,
270 const void *callout_info,
271 size_t callout_len,
272 void *aux);
273
274 extern struct key *request_key_async(struct key_type *type,
275 const char *description,
276 const void *callout_info,
277 size_t callout_len);
278
279 extern struct key *request_key_async_with_auxdata(struct key_type *type,
280 const char *description,
281 const void *callout_info,
282 size_t callout_len,
283 void *aux);
284
285 extern int wait_for_key_construction(struct key *key, bool intr);
286
287 extern int key_validate(const struct key *key);
288
289 extern key_ref_t key_create_or_update(key_ref_t keyring,
290 const char *type,
291 const char *description,
292 const void *payload,
293 size_t plen,
294 key_perm_t perm,
295 unsigned long flags);
296
297 extern int key_update(key_ref_t key,
298 const void *payload,
299 size_t plen);
300
301 extern int key_link(struct key *keyring,
302 struct key *key);
303
304 extern int key_unlink(struct key *keyring,
305 struct key *key);
306
307 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
308 const struct cred *cred,
309 key_perm_t perm,
310 unsigned long flags,
311 int (*restrict_link)(struct key *,
312 const struct key_type *,
313 const union key_payload *),
314 struct key *dest);
315
316 extern int restrict_link_reject(struct key *keyring,
317 const struct key_type *type,
318 const union key_payload *payload);
319
320 extern int keyring_clear(struct key *keyring);
321
322 extern key_ref_t keyring_search(key_ref_t keyring,
323 struct key_type *type,
324 const char *description);
325
326 extern int keyring_add_key(struct key *keyring,
327 struct key *key);
328
329 extern struct key *key_lookup(key_serial_t id);
330
key_serial(const struct key * key)331 static inline key_serial_t key_serial(const struct key *key)
332 {
333 return key ? key->serial : 0;
334 }
335
336 extern void key_set_timeout(struct key *, unsigned);
337
338 /*
339 * The permissions required on a key that we're looking up.
340 */
341 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
342 #define KEY_NEED_READ 0x02 /* Require permission to read content */
343 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
344 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
345 #define KEY_NEED_LINK 0x10 /* Require permission to link */
346 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
347 #define KEY_NEED_ALL 0x3f /* All the above permissions */
348
key_read_state(const struct key * key)349 static inline short key_read_state(const struct key *key)
350 {
351 /* Barrier versus mark_key_instantiated(). */
352 return smp_load_acquire(&key->state);
353 }
354
355 /**
356 * key_is_positive - Determine if a key has been positively instantiated
357 * @key: The key to check.
358 *
359 * Return true if the specified key has been positively instantiated, false
360 * otherwise.
361 */
key_is_positive(const struct key * key)362 static inline bool key_is_positive(const struct key *key)
363 {
364 return key_read_state(key) == KEY_IS_POSITIVE;
365 }
366
key_is_negative(const struct key * key)367 static inline bool key_is_negative(const struct key *key)
368 {
369 return key_read_state(key) < 0;
370 }
371
372 #define dereference_key_rcu(KEY) \
373 (rcu_dereference((KEY)->payload.rcu_data0))
374
375 #define dereference_key_locked(KEY) \
376 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
377 rwsem_is_locked(&((struct key *)(KEY))->sem)))
378
379 #define rcu_assign_keypointer(KEY, PAYLOAD) \
380 do { \
381 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
382 } while (0)
383
384 #ifdef CONFIG_SYSCTL
385 extern struct ctl_table key_sysctls[];
386 #endif
387 /*
388 * the userspace interface
389 */
390 extern int install_thread_keyring_to_cred(struct cred *cred);
391 extern void key_fsuid_changed(struct task_struct *tsk);
392 extern void key_fsgid_changed(struct task_struct *tsk);
393 extern void key_init(void);
394
395 #else /* CONFIG_KEYS */
396
397 #define key_validate(k) 0
398 #define key_serial(k) 0
399 #define key_get(k) ({ NULL; })
400 #define key_revoke(k) do { } while(0)
401 #define key_invalidate(k) do { } while(0)
402 #define key_put(k) do { } while(0)
403 #define key_ref_put(k) do { } while(0)
404 #define make_key_ref(k, p) NULL
405 #define key_ref_to_ptr(k) NULL
406 #define is_key_possessed(k) 0
407 #define key_fsuid_changed(t) do { } while(0)
408 #define key_fsgid_changed(t) do { } while(0)
409 #define key_init() do { } while(0)
410
411 #endif /* CONFIG_KEYS */
412 #endif /* __KERNEL__ */
413 #endif /* _LINUX_KEY_H */
414