1 /* key.h: authentication token and access key management
2 *
3 * Copyright (C) 2004 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/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 <asm/atomic.h>
23
24 #ifdef __KERNEL__
25
26 /* key handle serial number */
27 typedef int32_t key_serial_t;
28
29 /* key handle permissions mask */
30 typedef uint32_t key_perm_t;
31
32 struct key;
33
34 #ifdef CONFIG_KEYS
35
36 #undef KEY_DEBUGGING
37
38 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
39 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
40 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
41 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
42 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
43 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
44 #define KEY_POS_ALL 0x3f000000
45
46 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
47 #define KEY_USR_READ 0x00020000
48 #define KEY_USR_WRITE 0x00040000
49 #define KEY_USR_SEARCH 0x00080000
50 #define KEY_USR_LINK 0x00100000
51 #define KEY_USR_SETATTR 0x00200000
52 #define KEY_USR_ALL 0x003f0000
53
54 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
55 #define KEY_GRP_READ 0x00000200
56 #define KEY_GRP_WRITE 0x00000400
57 #define KEY_GRP_SEARCH 0x00000800
58 #define KEY_GRP_LINK 0x00001000
59 #define KEY_GRP_SETATTR 0x00002000
60 #define KEY_GRP_ALL 0x00003f00
61
62 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
63 #define KEY_OTH_READ 0x00000002
64 #define KEY_OTH_WRITE 0x00000004
65 #define KEY_OTH_SEARCH 0x00000008
66 #define KEY_OTH_LINK 0x00000010
67 #define KEY_OTH_SETATTR 0x00000020
68 #define KEY_OTH_ALL 0x0000003f
69
70 struct seq_file;
71 struct user_struct;
72 struct signal_struct;
73
74 struct key_type;
75 struct key_owner;
76 struct keyring_list;
77 struct keyring_name;
78
79 /*****************************************************************************/
80 /*
81 * key reference with possession attribute handling
82 *
83 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
84 * defined. This is because we abuse the bottom bit of the reference to carry a
85 * flag to indicate whether the calling process possesses that key in one of
86 * its keyrings.
87 *
88 * the key_ref_t has been made a separate type so that the compiler can reject
89 * attempts to dereference it without proper conversion.
90 *
91 * the three functions are used to assemble and disassemble references
92 */
93 typedef struct __key_reference_with_attributes *key_ref_t;
94
make_key_ref(const struct key * key,unsigned long possession)95 static inline key_ref_t make_key_ref(const struct key *key,
96 unsigned long possession)
97 {
98 return (key_ref_t) ((unsigned long) key | possession);
99 }
100
key_ref_to_ptr(const key_ref_t key_ref)101 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
102 {
103 return (struct key *) ((unsigned long) key_ref & ~1UL);
104 }
105
is_key_possessed(const key_ref_t key_ref)106 static inline unsigned long is_key_possessed(const key_ref_t key_ref)
107 {
108 return (unsigned long) key_ref & 1UL;
109 }
110
111 /*****************************************************************************/
112 /*
113 * authentication token / access credential / keyring
114 * - types of key include:
115 * - keyrings
116 * - disk encryption IDs
117 * - Kerberos TGTs and tickets
118 */
119 struct key {
120 atomic_t usage; /* number of references */
121 key_serial_t serial; /* key serial number */
122 struct rb_node serial_node;
123 struct key_type *type; /* type of key */
124 struct rw_semaphore sem; /* change vs change sem */
125 struct key_user *user; /* owner of this key */
126 void *security; /* security data for this key */
127 time_t expiry; /* time at which key expires (or 0) */
128 uid_t uid;
129 gid_t gid;
130 key_perm_t perm; /* access permissions */
131 unsigned short quotalen; /* length added to quota */
132 unsigned short datalen; /* payload data length
133 * - may not match RCU dereferenced payload
134 * - payload should contain own length
135 */
136
137 #ifdef KEY_DEBUGGING
138 unsigned magic;
139 #define KEY_DEBUG_MAGIC 0x18273645u
140 #define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
141 #endif
142
143 unsigned long flags; /* status flags (change with bitops) */
144 #define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
145 #define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
146 #define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
147 #define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
148 #define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
149 #define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
150
151 /* the description string
152 * - this is used to match a key against search criteria
153 * - this should be a printable string
154 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
155 */
156 char *description;
157
158 /* type specific data
159 * - this is used by the keyring type to index the name
160 */
161 union {
162 struct list_head link;
163 } type_data;
164
165 /* key data
166 * - this is used to hold the data actually used in cryptography or
167 * whatever
168 */
169 union {
170 unsigned long value;
171 void *data;
172 struct keyring_list *subscriptions;
173 } payload;
174 };
175
176 /*****************************************************************************/
177 /*
178 * kernel managed key type definition
179 */
180 typedef int (*request_key_actor_t)(struct key *key, struct key *authkey,
181 const char *op, void *aux);
182
183 struct key_type {
184 /* name of the type */
185 const char *name;
186
187 /* default payload length for quota precalculation (optional)
188 * - this can be used instead of calling key_payload_reserve(), that
189 * function only needs to be called if the real datalen is different
190 */
191 size_t def_datalen;
192
193 /* instantiate a key of this type
194 * - this method should call key_payload_reserve() to determine if the
195 * user's quota will hold the payload
196 */
197 int (*instantiate)(struct key *key, const void *data, size_t datalen);
198
199 /* update a key of this type (optional)
200 * - this method should call key_payload_reserve() to recalculate the
201 * quota consumption
202 * - the key must be locked against read when modifying
203 */
204 int (*update)(struct key *key, const void *data, size_t datalen);
205
206 /* match a key against a description */
207 int (*match)(const struct key *key, const void *desc);
208
209 /* clear some of the data from a key on revokation (optional)
210 * - the key's semaphore will be write-locked by the caller
211 */
212 void (*revoke)(struct key *key);
213
214 /* clear the data from a key (optional) */
215 void (*destroy)(struct key *key);
216
217 /* describe a key */
218 void (*describe)(const struct key *key, struct seq_file *p);
219
220 /* read a key's data (optional)
221 * - permission checks will be done by the caller
222 * - the key's semaphore will be readlocked by the caller
223 * - should return the amount of data that could be read, no matter how
224 * much is copied into the buffer
225 * - shouldn't do the copy if the buffer is NULL
226 */
227 long (*read)(const struct key *key, char __user *buffer, size_t buflen);
228
229 /* handle request_key() for this type instead of invoking
230 * /sbin/request-key (optional)
231 * - key is the key to instantiate
232 * - authkey is the authority to assume when instantiating this key
233 * - op is the operation to be done, usually "create"
234 * - the call must not return until the instantiation process has run
235 * its course
236 */
237 request_key_actor_t request_key;
238
239 /* internal fields */
240 struct list_head link; /* link in types list */
241 };
242
243 extern struct key_type key_type_keyring;
244
245 extern int register_key_type(struct key_type *ktype);
246 extern void unregister_key_type(struct key_type *ktype);
247
248 extern struct key *key_alloc(struct key_type *type,
249 const char *desc,
250 uid_t uid, gid_t gid,
251 struct task_struct *ctx,
252 key_perm_t perm,
253 unsigned long flags);
254
255
256 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
257 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
258 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
259
260 extern int key_payload_reserve(struct key *key, size_t datalen);
261 extern int key_instantiate_and_link(struct key *key,
262 const void *data,
263 size_t datalen,
264 struct key *keyring,
265 struct key *instkey);
266 extern int key_negate_and_link(struct key *key,
267 unsigned timeout,
268 struct key *keyring,
269 struct key *instkey);
270 extern void key_revoke(struct key *key);
271 extern void key_put(struct key *key);
272
key_get(struct key * key)273 static inline struct key *key_get(struct key *key)
274 {
275 if (key)
276 atomic_inc(&key->usage);
277 return key;
278 }
279
key_ref_put(key_ref_t key_ref)280 static inline void key_ref_put(key_ref_t key_ref)
281 {
282 key_put(key_ref_to_ptr(key_ref));
283 }
284
285 extern struct key *request_key(struct key_type *type,
286 const char *description,
287 const char *callout_info);
288
289 extern struct key *request_key_with_auxdata(struct key_type *type,
290 const char *description,
291 const char *callout_info,
292 void *aux);
293
294 extern int key_validate(struct key *key);
295
296 extern key_ref_t key_create_or_update(key_ref_t keyring,
297 const char *type,
298 const char *description,
299 const void *payload,
300 size_t plen,
301 unsigned long flags);
302
303 extern int key_update(key_ref_t key,
304 const void *payload,
305 size_t plen);
306
307 extern int key_link(struct key *keyring,
308 struct key *key);
309
310 extern int key_unlink(struct key *keyring,
311 struct key *key);
312
313 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
314 struct task_struct *ctx,
315 unsigned long flags,
316 struct key *dest);
317
318 extern int keyring_clear(struct key *keyring);
319
320 extern key_ref_t keyring_search(key_ref_t keyring,
321 struct key_type *type,
322 const char *description);
323
324 extern int keyring_add_key(struct key *keyring,
325 struct key *key);
326
327 extern struct key *key_lookup(key_serial_t id);
328
329 extern void keyring_replace_payload(struct key *key, void *replacement);
330
331 #define key_serial(key) ((key) ? (key)->serial : 0)
332
333 /*
334 * the userspace interface
335 */
336 extern struct key root_user_keyring, root_session_keyring;
337 extern int alloc_uid_keyring(struct user_struct *user,
338 struct task_struct *ctx);
339 extern void switch_uid_keyring(struct user_struct *new_user);
340 extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
341 extern int copy_thread_group_keys(struct task_struct *tsk);
342 extern void exit_keys(struct task_struct *tsk);
343 extern void exit_thread_group_keys(struct signal_struct *tg);
344 extern int suid_keys(struct task_struct *tsk);
345 extern int exec_keys(struct task_struct *tsk);
346 extern void key_fsuid_changed(struct task_struct *tsk);
347 extern void key_fsgid_changed(struct task_struct *tsk);
348 extern void key_init(void);
349
350 #define __install_session_keyring(tsk, keyring) \
351 ({ \
352 struct key *old_session = tsk->signal->session_keyring; \
353 tsk->signal->session_keyring = keyring; \
354 old_session; \
355 })
356
357 #else /* CONFIG_KEYS */
358
359 #define key_validate(k) 0
360 #define key_serial(k) 0
361 #define key_get(k) ({ NULL; })
362 #define key_put(k) do { } while(0)
363 #define key_ref_put(k) do { } while(0)
364 #define make_key_ref(k) ({ NULL; })
365 #define key_ref_to_ptr(k) ({ NULL; })
366 #define is_key_possessed(k) 0
367 #define alloc_uid_keyring(u,c) 0
368 #define switch_uid_keyring(u) do { } while(0)
369 #define __install_session_keyring(t, k) ({ NULL; })
370 #define copy_keys(f,t) 0
371 #define copy_thread_group_keys(t) 0
372 #define exit_keys(t) do { } while(0)
373 #define exit_thread_group_keys(tg) do { } while(0)
374 #define suid_keys(t) do { } while(0)
375 #define exec_keys(t) do { } while(0)
376 #define key_fsuid_changed(t) do { } while(0)
377 #define key_fsgid_changed(t) do { } while(0)
378 #define key_init() do { } while(0)
379
380 /* Initial keyrings */
381 extern struct key root_user_keyring;
382 extern struct key root_session_keyring;
383
384 #endif /* CONFIG_KEYS */
385 #endif /* __KERNEL__ */
386 #endif /* _LINUX_KEY_H */
387