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TOMOYO Linux Cross Reference
Linux/include/linux/key.h

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  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 
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 
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 
124 static inline bool is_key_possessed(const key_ref_t key_ref)
125 {
126         return (unsigned long) key_ref & 1UL;
127 }
128 
129 /*****************************************************************************/
130 /*
131  * authentication token / access credential / keyring
132  * - types of key include:
133  *   - keyrings
134  *   - disk encryption IDs
135  *   - Kerberos TGTs and tickets
136  */
137 struct key {
138         atomic_t                usage;          /* number of references */
139         key_serial_t            serial;         /* key serial number */
140         union {
141                 struct list_head graveyard_link;
142                 struct rb_node  serial_node;
143         };
144         struct rw_semaphore     sem;            /* change vs change sem */
145         struct key_user         *user;          /* owner of this key */
146         void                    *security;      /* security data for this key */
147         union {
148                 time_t          expiry;         /* time at which key expires (or 0) */
149                 time_t          revoked_at;     /* time at which key was revoked */
150         };
151         time_t                  last_used_at;   /* last time used for LRU keyring discard */
152         kuid_t                  uid;
153         kgid_t                  gid;
154         key_perm_t              perm;           /* access permissions */
155         unsigned short          quotalen;       /* length added to quota */
156         unsigned short          datalen;        /* payload data length
157                                                  * - may not match RCU dereferenced payload
158                                                  * - payload should contain own length
159                                                  */
160 
161 #ifdef KEY_DEBUGGING
162         unsigned                magic;
163 #define KEY_DEBUG_MAGIC         0x18273645u
164 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
165 #endif
166 
167         unsigned long           flags;          /* status flags (change with bitops) */
168 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
169 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
170 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
171 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
172 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
173 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
174 #define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
175 #define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
176 #define KEY_FLAG_BUILTIN        8       /* set if key is built in to the kernel */
177 #define KEY_FLAG_ROOT_CAN_INVAL 9       /* set if key can be invalidated by root without permission */
178 #define KEY_FLAG_KEEP           10      /* set if key should not be removed */
179 
180         /* the key type and key description string
181          * - the desc is used to match a key against search criteria
182          * - it should be a printable string
183          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
184          */
185         union {
186                 struct keyring_index_key index_key;
187                 struct {
188                         struct key_type *type;          /* type of key */
189                         char            *description;
190                 };
191         };
192 
193         /* key data
194          * - this is used to hold the data actually used in cryptography or
195          *   whatever
196          */
197         union {
198                 union key_payload payload;
199                 struct {
200                         /* Keyring bits */
201                         struct list_head name_link;
202                         struct assoc_array keys;
203                 };
204                 int reject_error;
205         };
206 
207         /* This is set on a keyring to restrict the addition of a link to a key
208          * to it.  If this method isn't provided then it is assumed that the
209          * keyring is open to any addition.  It is ignored for non-keyring
210          * keys.
211          *
212          * This is intended for use with rings of trusted keys whereby addition
213          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
214          * overrides this, allowing the kernel to add extra keys without
215          * restriction.
216          */
217         int (*restrict_link)(struct key *keyring,
218                              const struct key_type *type,
219                              const union key_payload *payload);
220 };
221 
222 extern struct key *key_alloc(struct key_type *type,
223                              const char *desc,
224                              kuid_t uid, kgid_t gid,
225                              const struct cred *cred,
226                              key_perm_t perm,
227                              unsigned long flags,
228                              int (*restrict_link)(struct key *,
229                                                   const struct key_type *,
230                                                   const union key_payload *));
231 
232 
233 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
234 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
235 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
236 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
237 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
238 
239 extern void key_revoke(struct key *key);
240 extern void key_invalidate(struct key *key);
241 extern void key_put(struct key *key);
242 
243 static inline struct key *__key_get(struct key *key)
244 {
245         atomic_inc(&key->usage);
246         return key;
247 }
248 
249 static inline struct key *key_get(struct key *key)
250 {
251         return key ? __key_get(key) : key;
252 }
253 
254 static inline void key_ref_put(key_ref_t key_ref)
255 {
256         key_put(key_ref_to_ptr(key_ref));
257 }
258 
259 extern struct key *request_key(struct key_type *type,
260                                const char *description,
261                                const char *callout_info);
262 
263 extern struct key *request_key_with_auxdata(struct key_type *type,
264                                             const char *description,
265                                             const void *callout_info,
266                                             size_t callout_len,
267                                             void *aux);
268 
269 extern struct key *request_key_async(struct key_type *type,
270                                      const char *description,
271                                      const void *callout_info,
272                                      size_t callout_len);
273 
274 extern struct key *request_key_async_with_auxdata(struct key_type *type,
275                                                   const char *description,
276                                                   const void *callout_info,
277                                                   size_t callout_len,
278                                                   void *aux);
279 
280 extern int wait_for_key_construction(struct key *key, bool intr);
281 
282 extern int key_validate(const struct key *key);
283 
284 extern key_ref_t key_create_or_update(key_ref_t keyring,
285                                       const char *type,
286                                       const char *description,
287                                       const void *payload,
288                                       size_t plen,
289                                       key_perm_t perm,
290                                       unsigned long flags);
291 
292 extern int key_update(key_ref_t key,
293                       const void *payload,
294                       size_t plen);
295 
296 extern int key_link(struct key *keyring,
297                     struct key *key);
298 
299 extern int key_unlink(struct key *keyring,
300                       struct key *key);
301 
302 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
303                                  const struct cred *cred,
304                                  key_perm_t perm,
305                                  unsigned long flags,
306                                  int (*restrict_link)(struct key *,
307                                                       const struct key_type *,
308                                                       const union key_payload *),
309                                  struct key *dest);
310 
311 extern int restrict_link_reject(struct key *keyring,
312                                 const struct key_type *type,
313                                 const union key_payload *payload);
314 
315 extern int keyring_clear(struct key *keyring);
316 
317 extern key_ref_t keyring_search(key_ref_t keyring,
318                                 struct key_type *type,
319                                 const char *description);
320 
321 extern int keyring_add_key(struct key *keyring,
322                            struct key *key);
323 
324 extern struct key *key_lookup(key_serial_t id);
325 
326 static inline key_serial_t key_serial(const struct key *key)
327 {
328         return key ? key->serial : 0;
329 }
330 
331 extern void key_set_timeout(struct key *, unsigned);
332 
333 /*
334  * The permissions required on a key that we're looking up.
335  */
336 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
337 #define KEY_NEED_READ   0x02    /* Require permission to read content */
338 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
339 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
340 #define KEY_NEED_LINK   0x10    /* Require permission to link */
341 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
342 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
343 
344 /**
345  * key_is_instantiated - Determine if a key has been positively instantiated
346  * @key: The key to check.
347  *
348  * Return true if the specified key has been positively instantiated, false
349  * otherwise.
350  */
351 static inline bool key_is_instantiated(const struct key *key)
352 {
353         return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
354                 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
355 }
356 
357 #define dereference_key_rcu(KEY)                                        \
358         (rcu_dereference((KEY)->payload.rcu_data0))
359 
360 #define dereference_key_locked(KEY)                                     \
361         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
362                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
363 
364 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
365 do {                                                                    \
366         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
367 } while (0)
368 
369 #ifdef CONFIG_SYSCTL
370 extern struct ctl_table key_sysctls[];
371 #endif
372 /*
373  * the userspace interface
374  */
375 extern int install_thread_keyring_to_cred(struct cred *cred);
376 extern void key_fsuid_changed(struct task_struct *tsk);
377 extern void key_fsgid_changed(struct task_struct *tsk);
378 extern void key_init(void);
379 
380 #else /* CONFIG_KEYS */
381 
382 #define key_validate(k)                 0
383 #define key_serial(k)                   0
384 #define key_get(k)                      ({ NULL; })
385 #define key_revoke(k)                   do { } while(0)
386 #define key_invalidate(k)               do { } while(0)
387 #define key_put(k)                      do { } while(0)
388 #define key_ref_put(k)                  do { } while(0)
389 #define make_key_ref(k, p)              NULL
390 #define key_ref_to_ptr(k)               NULL
391 #define is_key_possessed(k)             0
392 #define key_fsuid_changed(t)            do { } while(0)
393 #define key_fsgid_changed(t)            do { } while(0)
394 #define key_init()                      do { } while(0)
395 
396 #endif /* CONFIG_KEYS */
397 #endif /* __KERNEL__ */
398 #endif /* _LINUX_KEY_H */
399 

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