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
26 #ifdef __KERNEL__
27
28 /* key handle serial number */
29 typedef int32_t key_serial_t;
30
31 /* key handle permissions mask */
32 typedef uint32_t key_perm_t;
33
34 struct key;
35
36 #ifdef CONFIG_KEYS
37
38 #undef KEY_DEBUGGING
39
40 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */
41 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */
42 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */
43 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */
44 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */
45 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */
46 #define KEY_POS_ALL 0x3f000000
47
48 #define KEY_USR_VIEW 0x00010000 /* user permissions... */
49 #define KEY_USR_READ 0x00020000
50 #define KEY_USR_WRITE 0x00040000
51 #define KEY_USR_SEARCH 0x00080000
52 #define KEY_USR_LINK 0x00100000
53 #define KEY_USR_SETATTR 0x00200000
54 #define KEY_USR_ALL 0x003f0000
55
56 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */
57 #define KEY_GRP_READ 0x00000200
58 #define KEY_GRP_WRITE 0x00000400
59 #define KEY_GRP_SEARCH 0x00000800
60 #define KEY_GRP_LINK 0x00001000
61 #define KEY_GRP_SETATTR 0x00002000
62 #define KEY_GRP_ALL 0x00003f00
63
64 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */
65 #define KEY_OTH_READ 0x00000002
66 #define KEY_OTH_WRITE 0x00000004
67 #define KEY_OTH_SEARCH 0x00000008
68 #define KEY_OTH_LINK 0x00000010
69 #define KEY_OTH_SETATTR 0x00000020
70 #define KEY_OTH_ALL 0x0000003f
71
72 #define KEY_PERM_UNDEF 0xffffffff
73
74 struct seq_file;
75 struct user_struct;
76 struct signal_struct;
77 struct cred;
78
79 struct key_type;
80 struct key_owner;
81 struct keyring_list;
82 struct keyring_name;
83
84 /*****************************************************************************/
85 /*
86 * key reference with possession attribute handling
87 *
88 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
89 * defined. This is because we abuse the bottom bit of the reference to carry a
90 * flag to indicate whether the calling process possesses that key in one of
91 * its keyrings.
92 *
93 * the key_ref_t has been made a separate type so that the compiler can reject
94 * attempts to dereference it without proper conversion.
95 *
96 * the three functions are used to assemble and disassemble references
97 */
98 typedef struct __key_reference_with_attributes *key_ref_t;
99
make_key_ref(const struct key * key,unsigned long possession)100 static inline key_ref_t make_key_ref(const struct key *key,
101 unsigned long possession)
102 {
103 return (key_ref_t) ((unsigned long) key | possession);
104 }
105
key_ref_to_ptr(const key_ref_t key_ref)106 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
107 {
108 return (struct key *) ((unsigned long) key_ref & ~1UL);
109 }
110
is_key_possessed(const key_ref_t key_ref)111 static inline unsigned long is_key_possessed(const key_ref_t key_ref)
112 {
113 return (unsigned long) key_ref & 1UL;
114 }
115
116 /*****************************************************************************/
117 /*
118 * authentication token / access credential / keyring
119 * - types of key include:
120 * - keyrings
121 * - disk encryption IDs
122 * - Kerberos TGTs and tickets
123 */
124 struct key {
125 atomic_t usage; /* number of references */
126 key_serial_t serial; /* key serial number */
127 struct rb_node serial_node;
128 struct key_type *type; /* type of key */
129 struct rw_semaphore sem; /* change vs change sem */
130 struct key_user *user; /* owner of this key */
131 void *security; /* security data for this key */
132 union {
133 time_t expiry; /* time at which key expires (or 0) */
134 time_t revoked_at; /* time at which key was revoked */
135 };
136 uid_t uid;
137 gid_t gid;
138 key_perm_t perm; /* access permissions */
139 unsigned short quotalen; /* length added to quota */
140 unsigned short datalen; /* payload data length
141 * - may not match RCU dereferenced payload
142 * - payload should contain own length
143 */
144
145 #ifdef KEY_DEBUGGING
146 unsigned magic;
147 #define KEY_DEBUG_MAGIC 0x18273645u
148 #define KEY_DEBUG_MAGIC_X 0xf8e9dacbu
149 #endif
150
151 unsigned long flags; /* status flags (change with bitops) */
152 #define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */
153 #define KEY_FLAG_DEAD 1 /* set if key type has been deleted */
154 #define KEY_FLAG_REVOKED 2 /* set if key had been revoked */
155 #define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */
156 #define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */
157 #define KEY_FLAG_NEGATIVE 5 /* set if key is negative */
158 #define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */
159
160 /* the description string
161 * - this is used to match a key against search criteria
162 * - this should be a printable string
163 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
164 */
165 char *description;
166
167 /* type specific data
168 * - this is used by the keyring type to index the name
169 */
170 union {
171 struct list_head link;
172 unsigned long x[2];
173 void *p[2];
174 int reject_error;
175 } type_data;
176
177 /* key data
178 * - this is used to hold the data actually used in cryptography or
179 * whatever
180 */
181 union {
182 unsigned long value;
183 void __rcu *rcudata;
184 void *data;
185 struct keyring_list __rcu *subscriptions;
186 } payload;
187 };
188
189 extern struct key *key_alloc(struct key_type *type,
190 const char *desc,
191 uid_t uid, gid_t gid,
192 const struct cred *cred,
193 key_perm_t perm,
194 unsigned long flags);
195
196
197 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
198 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
199 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
200
201 extern void key_revoke(struct key *key);
202 extern void key_put(struct key *key);
203
key_get(struct key * key)204 static inline struct key *key_get(struct key *key)
205 {
206 if (key)
207 atomic_inc(&key->usage);
208 return key;
209 }
210
key_ref_put(key_ref_t key_ref)211 static inline void key_ref_put(key_ref_t key_ref)
212 {
213 key_put(key_ref_to_ptr(key_ref));
214 }
215
216 extern struct key *request_key(struct key_type *type,
217 const char *description,
218 const char *callout_info);
219
220 extern struct key *request_key_with_auxdata(struct key_type *type,
221 const char *description,
222 const void *callout_info,
223 size_t callout_len,
224 void *aux);
225
226 extern struct key *request_key_async(struct key_type *type,
227 const char *description,
228 const void *callout_info,
229 size_t callout_len);
230
231 extern struct key *request_key_async_with_auxdata(struct key_type *type,
232 const char *description,
233 const void *callout_info,
234 size_t callout_len,
235 void *aux);
236
237 extern int wait_for_key_construction(struct key *key, bool intr);
238
239 extern int key_validate(struct key *key);
240
241 extern key_ref_t key_create_or_update(key_ref_t keyring,
242 const char *type,
243 const char *description,
244 const void *payload,
245 size_t plen,
246 key_perm_t perm,
247 unsigned long flags);
248
249 extern int key_update(key_ref_t key,
250 const void *payload,
251 size_t plen);
252
253 extern int key_link(struct key *keyring,
254 struct key *key);
255
256 extern int key_unlink(struct key *keyring,
257 struct key *key);
258
259 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
260 const struct cred *cred,
261 unsigned long flags,
262 struct key *dest);
263
264 extern int keyring_clear(struct key *keyring);
265
266 extern key_ref_t keyring_search(key_ref_t keyring,
267 struct key_type *type,
268 const char *description);
269
270 extern int keyring_add_key(struct key *keyring,
271 struct key *key);
272
273 extern struct key *key_lookup(key_serial_t id);
274
key_serial(const struct key * key)275 static inline key_serial_t key_serial(const struct key *key)
276 {
277 return key ? key->serial : 0;
278 }
279
280 extern void key_set_timeout(struct key *, unsigned);
281
282 /**
283 * key_is_instantiated - Determine if a key has been positively instantiated
284 * @key: The key to check.
285 *
286 * Return true if the specified key has been positively instantiated, false
287 * otherwise.
288 */
key_is_instantiated(const struct key * key)289 static inline bool key_is_instantiated(const struct key *key)
290 {
291 return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
292 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
293 }
294
295 #define rcu_dereference_key(KEY) \
296 (rcu_dereference_protected((KEY)->payload.rcudata, \
297 rwsem_is_locked(&((struct key *)(KEY))->sem)))
298
299 #define rcu_assign_keypointer(KEY, PAYLOAD) \
300 (rcu_assign_pointer((KEY)->payload.rcudata, PAYLOAD))
301
302 #ifdef CONFIG_SYSCTL
303 extern ctl_table key_sysctls[];
304 #endif
305
306 extern void key_replace_session_keyring(void);
307
308 /*
309 * the userspace interface
310 */
311 extern int install_thread_keyring_to_cred(struct cred *cred);
312 extern void key_fsuid_changed(struct task_struct *tsk);
313 extern void key_fsgid_changed(struct task_struct *tsk);
314 extern void key_init(void);
315
316 #else /* CONFIG_KEYS */
317
318 #define key_validate(k) 0
319 #define key_serial(k) 0
320 #define key_get(k) ({ NULL; })
321 #define key_revoke(k) do { } while(0)
322 #define key_put(k) do { } while(0)
323 #define key_ref_put(k) do { } while(0)
324 #define make_key_ref(k, p) NULL
325 #define key_ref_to_ptr(k) NULL
326 #define is_key_possessed(k) 0
327 #define key_fsuid_changed(t) do { } while(0)
328 #define key_fsgid_changed(t) do { } while(0)
329 #define key_init() do { } while(0)
330 #define key_replace_session_keyring() do { } while(0)
331
332 #endif /* CONFIG_KEYS */
333 #endif /* __KERNEL__ */
334 #endif /* _LINUX_KEY_H */
335