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
make_key_ref(const struct key * key,bool possession)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
key_ref_to_ptr(const key_ref_t key_ref)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
is_key_possessed(const key_ref_t key_ref)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 #define KEY_FLAG_BUILTIN 10 /* set if key is builtin */
174 #define KEY_FLAG_ROOT_CAN_INVAL 11 /* set if key can be invalidated by root without permission */
175 #define KEY_FLAG_UID_KEYRING 12 /* set if key is a user or user session keyring */
176
177 /* the key type and key description string
178 * - the desc is used to match a key against search criteria
179 * - it should be a printable string
180 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
181 */
182 union {
183 struct keyring_index_key index_key;
184 struct {
185 struct key_type *type; /* type of key */
186 char *description;
187 };
188 };
189
190 /* type specific data
191 * - this is used by the keyring type to index the name
192 */
193 union {
194 struct list_head link;
195 unsigned long x[2];
196 void *p[2];
197 int reject_error;
198 } type_data;
199
200 /* key data
201 * - this is used to hold the data actually used in cryptography or
202 * whatever
203 */
204 union {
205 union {
206 unsigned long value;
207 void __rcu *rcudata;
208 void *data;
209 void *data2[2];
210 } payload;
211 struct assoc_array keys;
212 };
213 };
214
215 extern struct key *key_alloc(struct key_type *type,
216 const char *desc,
217 kuid_t uid, kgid_t gid,
218 const struct cred *cred,
219 key_perm_t perm,
220 unsigned long flags);
221
222
223 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
224 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
225 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
226 #define KEY_ALLOC_TRUSTED 0x0004 /* Key should be flagged as trusted */
227 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
228
229 extern void key_revoke(struct key *key);
230 extern void key_invalidate(struct key *key);
231 extern void key_put(struct key *key);
232
__key_get(struct key * key)233 static inline struct key *__key_get(struct key *key)
234 {
235 atomic_inc(&key->usage);
236 return key;
237 }
238
key_get(struct key * key)239 static inline struct key *key_get(struct key *key)
240 {
241 return key ? __key_get(key) : key;
242 }
243
key_ref_put(key_ref_t key_ref)244 static inline void key_ref_put(key_ref_t key_ref)
245 {
246 key_put(key_ref_to_ptr(key_ref));
247 }
248
249 extern struct key *request_key(struct key_type *type,
250 const char *description,
251 const char *callout_info);
252
253 extern struct key *request_key_with_auxdata(struct key_type *type,
254 const char *description,
255 const void *callout_info,
256 size_t callout_len,
257 void *aux);
258
259 extern struct key *request_key_async(struct key_type *type,
260 const char *description,
261 const void *callout_info,
262 size_t callout_len);
263
264 extern struct key *request_key_async_with_auxdata(struct key_type *type,
265 const char *description,
266 const void *callout_info,
267 size_t callout_len,
268 void *aux);
269
270 extern int wait_for_key_construction(struct key *key, bool intr);
271
272 extern int key_validate(const struct key *key);
273
274 extern key_ref_t key_create_or_update(key_ref_t keyring,
275 const char *type,
276 const char *description,
277 const void *payload,
278 size_t plen,
279 key_perm_t perm,
280 unsigned long flags);
281
282 extern int key_update(key_ref_t key,
283 const void *payload,
284 size_t plen);
285
286 extern int key_link(struct key *keyring,
287 struct key *key);
288
289 extern int key_unlink(struct key *keyring,
290 struct key *key);
291
292 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
293 const struct cred *cred,
294 key_perm_t perm,
295 unsigned long flags,
296 struct key *dest);
297
298 extern int keyring_clear(struct key *keyring);
299
300 extern key_ref_t keyring_search(key_ref_t keyring,
301 struct key_type *type,
302 const char *description);
303
304 extern int keyring_add_key(struct key *keyring,
305 struct key *key);
306
307 extern struct key *key_lookup(key_serial_t id);
308
key_serial(const struct key * key)309 static inline key_serial_t key_serial(const struct key *key)
310 {
311 return key ? key->serial : 0;
312 }
313
314 extern void key_set_timeout(struct key *, unsigned);
315
316 /*
317 * The permissions required on a key that we're looking up.
318 */
319 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */
320 #define KEY_NEED_READ 0x02 /* Require permission to read content */
321 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */
322 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */
323 #define KEY_NEED_LINK 0x10 /* Require permission to link */
324 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */
325 #define KEY_NEED_ALL 0x3f /* All the above permissions */
326
327 /**
328 * key_is_instantiated - Determine if a key has been positively instantiated
329 * @key: The key to check.
330 *
331 * Return true if the specified key has been positively instantiated, false
332 * otherwise.
333 */
key_is_instantiated(const struct key * key)334 static inline bool key_is_instantiated(const struct key *key)
335 {
336 return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
337 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
338 }
339
340 #define rcu_dereference_key(KEY) \
341 (rcu_dereference_protected((KEY)->payload.rcudata, \
342 rwsem_is_locked(&((struct key *)(KEY))->sem)))
343
344 #define rcu_assign_keypointer(KEY, PAYLOAD) \
345 do { \
346 rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD)); \
347 } while (0)
348
349 #ifdef CONFIG_SYSCTL
350 extern struct ctl_table key_sysctls[];
351 #endif
352 /*
353 * the userspace interface
354 */
355 extern int install_thread_keyring_to_cred(struct cred *cred);
356 extern void key_fsuid_changed(struct task_struct *tsk);
357 extern void key_fsgid_changed(struct task_struct *tsk);
358 extern void key_init(void);
359
360 #else /* CONFIG_KEYS */
361
362 #define key_validate(k) 0
363 #define key_serial(k) 0
364 #define key_get(k) ({ NULL; })
365 #define key_revoke(k) do { } while(0)
366 #define key_invalidate(k) do { } while(0)
367 #define key_put(k) do { } while(0)
368 #define key_ref_put(k) do { } while(0)
369 #define make_key_ref(k, p) NULL
370 #define key_ref_to_ptr(k) NULL
371 #define is_key_possessed(k) 0
372 #define key_fsuid_changed(t) do { } while(0)
373 #define key_fsgid_changed(t) do { } while(0)
374 #define key_init() do { } while(0)
375
376 #endif /* CONFIG_KEYS */
377 #endif /* __KERNEL__ */
378 #endif /* _LINUX_KEY_H */
379