include/linux/key.h

   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
 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
 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
 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         union {
 128                 struct list_head graveyard_link;
 129                 struct rb_node  serial_node;
 130         };
 131         struct key_type         *type;          /* type of key */
 132         struct rw_semaphore     sem;            /* change vs change sem */
 133         struct key_user         *user;          /* owner of this key */
 134         void                    *security;      /* security data for this key */
 135         union {
 136                 time_t          expiry;         /* time at which key expires (or 0) */
 137                 time_t          revoked_at;     /* time at which key was revoked */
 138         };
 139         time_t                  last_used_at;   /* last time used for LRU keyring discard */
 140         uid_t                   uid;
 141         gid_t                   gid;
 142         key_perm_t              perm;           /* access permissions */
 143         unsigned short          quotalen;       /* length added to quota */
 144         unsigned short          datalen;        /* payload data length
 145                                                  * - may not match RCU dereferenced payload
 146                                                  * - payload should contain own length
 147                                                  */
 148
 149 #ifdef KEY_DEBUGGING
 150         unsigned                magic;
 151 #define KEY_DEBUG_MAGIC         0x18273645u
 152 #define KEY_DEBUG_MAGIC_X       0xf8e9dacbu
 153 #endif
 154
 155         unsigned long           flags;          /* status flags (change with bitops) */
 156 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 157 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 158 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 159 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 160 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 161 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 162 #define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 163 #define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 164
 165         /* the description string
 166          * - this is used to match a key against search criteria
 167          * - this should be a printable string
 168          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 169          */
 170         char                    *description;
 171
 172         /* type specific data
 173          * - this is used by the keyring type to index the name
 174          */
 175         union {
 176                 struct list_head        link;
 177                 unsigned long           x[2];
 178                 void                    *p[2];
 179                 int                     reject_error;
 180         } type_data;
 181
 182         /* key data
 183          * - this is used to hold the data actually used in cryptography or
 184          *   whatever
 185          */
 186         union {
 187                 unsigned long           value;
 188                 void __rcu              *rcudata;
 189                 void                    *data;
 190                 struct keyring_list __rcu *subscriptions;
 191         } payload;
 192 };
 193
 194 extern struct key *key_alloc(struct key_type *type,
 195                              const char *desc,
 196                              uid_t uid, gid_t gid,
 197                              const struct cred *cred,
 198                              key_perm_t perm,
 199                              unsigned long flags);
 200
 201
 202 #define KEY_ALLOC_IN_QUOTA      0x0000  /* add to quota, reject if would overrun */
 203 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001  /* add to quota, permit even if overrun */
 204 #define KEY_ALLOC_NOT_IN_QUOTA  0x0002  /* not in quota */
 205
 206 extern void key_revoke(struct key *key);
 207 extern void key_invalidate(struct key *key);
 208 extern void key_put(struct key *key);
 209
 210 static inline struct key *key_get(struct key *key)
 211 {
 212         if (key)
 213                 atomic_inc(&key->usage);
 214         return key;
 215 }
 216
 217 static inline void key_ref_put(key_ref_t key_ref)
 218 {
 219         key_put(key_ref_to_ptr(key_ref));
 220 }
 221
 222 extern struct key *request_key(struct key_type *type,
 223                                const char *description,
 224                                const char *callout_info);
 225
 226 extern struct key *request_key_with_auxdata(struct key_type *type,
 227                                             const char *description,
 228                                             const void *callout_info,
 229                                             size_t callout_len,
 230                                             void *aux);
 231
 232 extern struct key *request_key_async(struct key_type *type,
 233                                      const char *description,
 234                                      const void *callout_info,
 235                                      size_t callout_len);
 236
 237 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 238                                                   const char *description,
 239                                                   const void *callout_info,
 240                                                   size_t callout_len,
 241                                                   void *aux);
 242
 243 extern int wait_for_key_construction(struct key *key, bool intr);
 244
 245 extern int key_validate(const struct key *key);
 246
 247 extern key_ref_t key_create_or_update(key_ref_t keyring,
 248                                       const char *type,
 249                                       const char *description,
 250                                       const void *payload,
 251                                       size_t plen,
 252                                       key_perm_t perm,
 253                                       unsigned long flags);
 254
 255 extern int key_update(key_ref_t key,
 256                       const void *payload,
 257                       size_t plen);
 258
 259 extern int key_link(struct key *keyring,
 260                     struct key *key);
 261
 262 extern int key_unlink(struct key *keyring,
 263                       struct key *key);
 264
 265 extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
 266                                  const struct cred *cred,
 267                                  unsigned long flags,
 268                                  struct key *dest);
 269
 270 extern int keyring_clear(struct key *keyring);
 271
 272 extern key_ref_t keyring_search(key_ref_t keyring,
 273                                 struct key_type *type,
 274                                 const char *description);
 275
 276 extern int keyring_add_key(struct key *keyring,
 277                            struct key *key);
 278
 279 extern struct key *key_lookup(key_serial_t id);
 280
 281 static inline key_serial_t key_serial(const struct key *key)
 282 {
 283         return key ? key->serial : 0;
 284 }
 285
 286 extern void key_set_timeout(struct key *, unsigned);
 287
 288 /**
 289  * key_is_instantiated - Determine if a key has been positively instantiated
 290  * @key: The key to check.
 291  *
 292  * Return true if the specified key has been positively instantiated, false
 293  * otherwise.
 294  */
 295 static inline bool key_is_instantiated(const struct key *key)
 296 {
 297         return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 298                 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 299 }
 300
 301 #define rcu_dereference_key(KEY)                                        \
 302         (rcu_dereference_protected((KEY)->payload.rcudata,              \
 303                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 304
 305 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 306         (rcu_assign_pointer((KEY)->payload.rcudata, PAYLOAD))
 307
 308 #ifdef CONFIG_SYSCTL
 309 extern ctl_table key_sysctls[];
 310 #endif
 311
 312 extern void key_replace_session_keyring(void);
 313
 314 /*
 315  * the userspace interface
 316  */
 317 extern int install_thread_keyring_to_cred(struct cred *cred);
 318 extern void key_fsuid_changed(struct task_struct *tsk);
 319 extern void key_fsgid_changed(struct task_struct *tsk);
 320 extern void key_init(void);
 321
 322 #else /* CONFIG_KEYS */
 323
 324 #define key_validate(k)                 0
 325 #define key_serial(k)                   0
 326 #define key_get(k)                      ({ NULL; })
 327 #define key_revoke(k)                   do { } while(0)
 328 #define key_invalidate(k)               do { } while(0)
 329 #define key_put(k)                      do { } while(0)
 330 #define key_ref_put(k)                  do { } while(0)
 331 #define make_key_ref(k, p)              NULL
 332 #define key_ref_to_ptr(k)               NULL
 333 #define is_key_possessed(k)             0
 334 #define key_fsuid_changed(t)            do { } while(0)
 335 #define key_fsgid_changed(t)            do { } while(0)
 336 #define key_init()                      do { } while(0)
 337 #define key_replace_session_keyring()   do { } while(0)
 338
 339 #endif /* CONFIG_KEYS */
 340 #endif /* __KERNEL__ */
 341 #endif /* _LINUX_KEY_H */