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 #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 rcu_dereference_key(KEY)                                        \
 358         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 359                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 360
 361 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 362 do {                                                                    \
 363         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 364 } while (0)
 365
 366 #ifdef CONFIG_SYSCTL
 367 extern struct ctl_table key_sysctls[];
 368 #endif
 369 /*
 370  * the userspace interface
 371  */
 372 extern int install_thread_keyring_to_cred(struct cred *cred);
 373 extern void key_fsuid_changed(struct task_struct *tsk);
 374 extern void key_fsgid_changed(struct task_struct *tsk);
 375 extern void key_init(void);
 376
 377 #else /* CONFIG_KEYS */
 378
 379 #define key_validate(k)                 0
 380 #define key_serial(k)                   0
 381 #define key_get(k)                      ({ NULL; })
 382 #define key_revoke(k)                   do { } while(0)
 383 #define key_invalidate(k)               do { } while(0)
 384 #define key_put(k)                      do { } while(0)
 385 #define key_ref_put(k)                  do { } while(0)
 386 #define make_key_ref(k, p)              NULL
 387 #define key_ref_to_ptr(k)               NULL
 388 #define is_key_possessed(k)             0
 389 #define key_fsuid_changed(t)            do { } while(0)
 390 #define key_fsgid_changed(t)            do { } while(0)
 391 #define key_init()                      do { } while(0)
 392
 393 #endif /* CONFIG_KEYS */
 394 #endif /* __KERNEL__ */
 395 #endif /* _LINUX_KEY_H */