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 /*****************************************************************************/
93 /*
94 * key reference with possession attribute handling
95 *
96 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
97 * defined. This is because we abuse the bottom bit of the reference to carry a
98 * flag to indicate whether the calling process possesses that key in one of
99 * its keyrings.
100 *
101 * the key_ref_t has been made a separate type so that the compiler can reject
102 * attempts to dereference it without proper conversion.
103 *
104 * the three functions are used to assemble and disassemble references
105 */
106 typedef struct __key_reference_with_attributes *key_ref_t;
107
108 static inline key_ref_t make_key_ref(const struct key *key,
109 bool possession)
110 {
111 return (key_ref_t) ((unsigned long) key | possession);
112 }
113
114 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
115 {
116 return (struct key *) ((unsigned long) key_ref & ~1UL);
117 }
118
119 static inline bool is_key_possessed(const key_ref_t key_ref)
120 {
121 return (unsigned long) key_ref & 1UL;
122 }
123
124 /*****************************************************************************/
125 /*
126 * authentication token / access credential / keyring
127 * - types of key include:
128 * - keyrings
129 * - disk encryption IDs
130 * - Kerberos TGTs and tickets
131 */
132 struct key {
133 atomic_t usage; /* number of references */
134 key_serial_t serial; /* key serial number */
135 union {
136 struct list_head graveyard_link;
137 struct rb_node serial_node;
138 };
139 struct rw_semaphore sem; /* change vs change sem */
140 struct key_user *user; /* owner of this key */
141 void *security; /* security data for this key */
142 union {
143 time_t expiry; /* time at which key expires (or 0) */
144 time_t revoked_at; /* time at which key was revoked */
145 };
146 time_t last_used_at; /* last time used for LRU keyring discard */
147 kuid_t uid;
148 kgid_t gid;
149 key_perm_t perm; /* access permissions */
150 unsigned short quotalen; /* length added to quota */
151 unsigned short datalen; /* payload data length
152 * - may not match RCU dereferenced payload
153 * - payload should contain own length
154 */
155
156 #ifdef KEY_DEBUGGING
157 unsigned magic;
158 #define KEY_DEBUG_MAGIC 0x18273645u
159 #define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
160 #endif
161
162 unsigned long flags; /* status flags (change with bitops) */
163 #define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
164 #define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
165 #define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
166 #define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
167 #define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
168 #define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
169 #define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */
170 #define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */
171 #define KEY_FLAG_TRUSTED 8 /* set if key is trusted */
172 #define KEY_FLAG_TRUSTED_ONLY 9 /* set if keyring only accepts links to trusted keys */
173
174 /* the key type and key description string
175 * - the desc is used to match a key against search criteria
176 * - it should be a printable string
177 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
178 */
179 union {
180 struct keyring_index_key index_key;
181 struct {
182 struct key_type *type; /* type of key */
183 char *description;
184 };
185 };
186
187 /* type specific data
188 * - this is used by the keyring type to index the name
189 */
190 union {
191 struct list_head link;
192 unsigned long x[2];
193 void *p[2];
194 int reject_error;
195 } type_data;
196
197 /* key data
198 * - this is used to hold the data actually used in cryptography or
199 * whatever
200 */
201 union {
202 union {
203 unsigned long value;
204 void __rcu *rcudata;
205 void *data;
206 void *data2[2];
207 } payload;
208 struct assoc_array keys;
209 };
210 };
211
212 extern struct key *key_alloc(struct key_type *type,
213 const char *desc,
214 kuid_t uid, kgid_t gid,
215 const struct cred *cred,
216 key_perm_t perm,
217 unsigned long flags);
218
219
220 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
221 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
222 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
223 #define KEY_ALLOC_TRUSTED 0x0004 /* Key should be flagged as trusted */
224
225 extern void key_revoke(struct key *key);
226 extern void key_invalidate(struct key *key);
227 extern void key_put(struct key *key);
228
229 static inline struct key *__key_get(struct key *key)
230 {
231 atomic_inc(&key->usage);
232 return key;
233 }
234
235 static inline struct key *key_get(struct key *key)
236 {
237 return key ? __key_get(key) : key;
238 }
239
240 static inline void key_ref_put(key_ref_t key_ref)
241 {
242 key_put(key_ref_to_ptr(key_ref));
243 }
244
245 extern struct key *request_key(struct key_type *type,
246 const char *description,
247 const char *callout_info);
248
249 extern struct key *request_key_with_auxdata(struct key_type *type,
250 const char *description,
251 const void *callout_info,
252 size_t callout_len,
253 void *aux);
254
255 extern struct key *request_key_async(struct key_type *type,
256 const char *description,
257 const void *callout_info,
258 size_t callout_len);
259
260 extern struct key *request_key_async_with_auxdata(struct key_type *type,
261 const char *description,
262 const void *callout_info,
263 size_t callout_len,
264 void *aux);
265
266 extern int wait_for_key_construction(struct key *key, bool intr);
267
268 extern int key_validate(const struct key *key);
269
270 extern key_ref_t key_create_or_update(key_ref_t keyring,
271 const char *type,
272 const char *description,
273 const void *payload,
274 size_t plen,
275 key_perm_t perm,
276 unsigned long flags);
277
278 extern int key_update(key_ref_t key,
279 const void *payload,
280 size_t plen);
281
282 extern int key_link(struct key *keyring,
283 struct key *key);
284
285 extern int key_unlink(struct key *keyring,
286 struct key *key);
287
288 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
289 const struct cred *cred,
290 key_perm_t perm,
291 unsigned long flags,
292 struct key *dest);
293
294 extern int keyring_clear(struct key *keyring);
295
296 extern key_ref_t keyring_search(key_ref_t keyring,
297 struct key_type *type,
298 const char *description);
299
300 extern int keyring_add_key(struct key *keyring,
301 struct key *key);
302
303 extern struct key *key_lookup(key_serial_t id);
304
305 static inline key_serial_t key_serial(const struct key *key)
306 {
307 return key ? key->serial : 0;
308 }
309
310 extern void key_set_timeout(struct key *, unsigned);
311
312 /**
313 * key_is_instantiated - Determine if a key has been positively instantiated
314 * @key: The key to check.
315 *
316 * Return true if the specified key has been positively instantiated, false
317 * otherwise.
318 */
319 static inline bool key_is_instantiated(const struct key *key)
320 {
321 return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
322 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
323 }
324
325 #define rcu_dereference_key(KEY) \
326 (rcu_dereference_protected((KEY)->payload.rcudata, \
327 rwsem_is_locked(&((struct key *)(KEY))->sem)))
328
329 #define rcu_assign_keypointer(KEY, PAYLOAD) \
330 do { \
331 rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD)); \
332 } while (0)
333
334 #ifdef CONFIG_SYSCTL
335 extern ctl_table key_sysctls[];
336 #endif
337 /*
338 * the userspace interface
339 */
340 extern int install_thread_keyring_to_cred(struct cred *cred);
341 extern void key_fsuid_changed(struct task_struct *tsk);
342 extern void key_fsgid_changed(struct task_struct *tsk);
343 extern void key_init(void);
344
345 #else /* CONFIG_KEYS */
346
347 #define key_validate(k) 0
348 #define key_serial(k) 0
349 #define key_get(k) ({ NULL; })
350 #define key_revoke(k) do { } while(0)
351 #define key_invalidate(k) do { } while(0)
352 #define key_put(k) do { } while(0)
353 #define key_ref_put(k) do { } while(0)
354 #define make_key_ref(k, p) NULL
355 #define key_ref_to_ptr(k) NULL
356 #define is_key_possessed(k) 0
357 #define key_fsuid_changed(t) do { } while(0)
358 #define key_fsgid_changed(t) do { } while(0)
359 #define key_init() do { } while(0)
360
361 #endif /* CONFIG_KEYS */
362 #endif /* __KERNEL__ */
363 #endif /* _LINUX_KEY_H */
364
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