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/core.rst 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 #include <linux/refcount.h>
  27
  28 #ifdef __KERNEL__
  29 #include <linux/uidgid.h>
  30
  31 /* key handle serial number */
  32 typedef int32_t key_serial_t;
  33
  34 /* key handle permissions mask */
  35 typedef uint32_t key_perm_t;
  36
  37 struct key;
  38
  39 #ifdef CONFIG_KEYS
  40
  41 #undef KEY_DEBUGGING
  42
  43 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  44 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  45 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  46 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  47 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  48 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  49 #define KEY_POS_ALL     0x3f000000
  50
  51 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  52 #define KEY_USR_READ    0x00020000
  53 #define KEY_USR_WRITE   0x00040000
  54 #define KEY_USR_SEARCH  0x00080000
  55 #define KEY_USR_LINK    0x00100000
  56 #define KEY_USR_SETATTR 0x00200000
  57 #define KEY_USR_ALL     0x003f0000
  58
  59 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  60 #define KEY_GRP_READ    0x00000200
  61 #define KEY_GRP_WRITE   0x00000400
  62 #define KEY_GRP_SEARCH  0x00000800
  63 #define KEY_GRP_LINK    0x00001000
  64 #define KEY_GRP_SETATTR 0x00002000
  65 #define KEY_GRP_ALL     0x00003f00
  66
  67 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  68 #define KEY_OTH_READ    0x00000002
  69 #define KEY_OTH_WRITE   0x00000004
  70 #define KEY_OTH_SEARCH  0x00000008
  71 #define KEY_OTH_LINK    0x00000010
  72 #define KEY_OTH_SETATTR 0x00000020
  73 #define KEY_OTH_ALL     0x0000003f
  74
  75 #define KEY_PERM_UNDEF  0xffffffff
  76
  77 struct seq_file;
  78 struct user_struct;
  79 struct signal_struct;
  80 struct cred;
  81
  82 struct key_type;
  83 struct key_owner;
  84 struct keyring_list;
  85 struct keyring_name;
  86
  87 struct keyring_index_key {
  88         struct key_type         *type;
  89         const char              *description;
  90         size_t                  desc_len;
  91 };
  92
  93 union key_payload {
  94         void __rcu              *rcu_data0;
  95         void                    *data[4];
  96 };
  97
  98 /*****************************************************************************/
  99 /*
 100  * key reference with possession attribute handling
 101  *
 102  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 103  * defined. This is because we abuse the bottom bit of the reference to carry a
 104  * flag to indicate whether the calling process possesses that key in one of
 105  * its keyrings.
 106  *
 107  * the key_ref_t has been made a separate type so that the compiler can reject
 108  * attempts to dereference it without proper conversion.
 109  *
 110  * the three functions are used to assemble and disassemble references
 111  */
 112 typedef struct __key_reference_with_attributes *key_ref_t;
 113
 114 static inline key_ref_t make_key_ref(const struct key *key,
 115                                      bool possession)
 116 {
 117         return (key_ref_t) ((unsigned long) key | possession);
 118 }
 119
 120 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 121 {
 122         return (struct key *) ((unsigned long) key_ref & ~1UL);
 123 }
 124
 125 static inline bool is_key_possessed(const key_ref_t key_ref)
 126 {
 127         return (unsigned long) key_ref & 1UL;
 128 }
 129
 130 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 131                                         const struct key_type *type,
 132                                         const union key_payload *payload,
 133                                         struct key *restriction_key);
 134
 135 struct key_restriction {
 136         key_restrict_link_func_t check;
 137         struct key *key;
 138         struct key_type *keytype;
 139 };
 140
 141 /*****************************************************************************/
 142 /*
 143  * authentication token / access credential / keyring
 144  * - types of key include:
 145  *   - keyrings
 146  *   - disk encryption IDs
 147  *   - Kerberos TGTs and tickets
 148  */
 149 struct key {
 150         refcount_t              usage;          /* number of references */
 151         key_serial_t            serial;         /* key serial number */
 152         union {
 153                 struct list_head graveyard_link;
 154                 struct rb_node  serial_node;
 155         };
 156         struct rw_semaphore     sem;            /* change vs change sem */
 157         struct key_user         *user;          /* owner of this key */
 158         void                    *security;      /* security data for this key */
 159         union {
 160                 time_t          expiry;         /* time at which key expires (or 0) */
 161                 time_t          revoked_at;     /* time at which key was revoked */
 162         };
 163         time_t                  last_used_at;   /* last time used for LRU keyring discard */
 164         kuid_t                  uid;
 165         kgid_t                  gid;
 166         key_perm_t              perm;           /* access permissions */
 167         unsigned short          quotalen;       /* length added to quota */
 168         unsigned short          datalen;        /* payload data length
 169                                                  * - may not match RCU dereferenced payload
 170                                                  * - payload should contain own length
 171                                                  */
 172
 173 #ifdef KEY_DEBUGGING
 174         unsigned                magic;
 175 #define KEY_DEBUG_MAGIC         0x18273645u
 176 #endif
 177
 178         unsigned long           flags;          /* status flags (change with bitops) */
 179 #define KEY_FLAG_INSTANTIATED   0       /* set if key has been instantiated */
 180 #define KEY_FLAG_DEAD           1       /* set if key type has been deleted */
 181 #define KEY_FLAG_REVOKED        2       /* set if key had been revoked */
 182 #define KEY_FLAG_IN_QUOTA       3       /* set if key consumes quota */
 183 #define KEY_FLAG_USER_CONSTRUCT 4       /* set if key is being constructed in userspace */
 184 #define KEY_FLAG_NEGATIVE       5       /* set if key is negative */
 185 #define KEY_FLAG_ROOT_CAN_CLEAR 6       /* set if key can be cleared by root without permission */
 186 #define KEY_FLAG_INVALIDATED    7       /* set if key has been invalidated */
 187 #define KEY_FLAG_BUILTIN        8       /* set if key is built in to the kernel */
 188 #define KEY_FLAG_ROOT_CAN_INVAL 9       /* set if key can be invalidated by root without permission */
 189 #define KEY_FLAG_KEEP           10      /* set if key should not be removed */
 190
 191         /* the key type and key description string
 192          * - the desc is used to match a key against search criteria
 193          * - it should be a printable string
 194          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 195          */
 196         union {
 197                 struct keyring_index_key index_key;
 198                 struct {
 199                         struct key_type *type;          /* type of key */
 200                         char            *description;
 201                 };
 202         };
 203
 204         /* key data
 205          * - this is used to hold the data actually used in cryptography or
 206          *   whatever
 207          */
 208         union {
 209                 union key_payload payload;
 210                 struct {
 211                         /* Keyring bits */
 212                         struct list_head name_link;
 213                         struct assoc_array keys;
 214                 };
 215                 int reject_error;
 216         };
 217
 218         /* This is set on a keyring to restrict the addition of a link to a key
 219          * to it.  If this structure isn't provided then it is assumed that the
 220          * keyring is open to any addition.  It is ignored for non-keyring
 221          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 222          * or key_alloc().
 223          *
 224          * This is intended for use with rings of trusted keys whereby addition
 225          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 226          * overrides this, allowing the kernel to add extra keys without
 227          * restriction.
 228          */
 229         struct key_restriction *restrict_link;
 230 };
 231
 232 extern struct key *key_alloc(struct key_type *type,
 233                              const char *desc,
 234                              kuid_t uid, kgid_t gid,
 235                              const struct cred *cred,
 236                              key_perm_t perm,
 237                              unsigned long flags,
 238                              struct key_restriction *restrict_link);
 239
 240
 241 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 242 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 243 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 244 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 245 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 246
 247 extern void key_revoke(struct key *key);
 248 extern void key_invalidate(struct key *key);
 249 extern void key_put(struct key *key);
 250
 251 static inline struct key *__key_get(struct key *key)
 252 {
 253         refcount_inc(&key->usage);
 254         return key;
 255 }
 256
 257 static inline struct key *key_get(struct key *key)
 258 {
 259         return key ? __key_get(key) : key;
 260 }
 261
 262 static inline void key_ref_put(key_ref_t key_ref)
 263 {
 264         key_put(key_ref_to_ptr(key_ref));
 265 }
 266
 267 extern struct key *request_key(struct key_type *type,
 268                                const char *description,
 269                                const char *callout_info);
 270
 271 extern struct key *request_key_with_auxdata(struct key_type *type,
 272                                             const char *description,
 273                                             const void *callout_info,
 274                                             size_t callout_len,
 275                                             void *aux);
 276
 277 extern struct key *request_key_async(struct key_type *type,
 278                                      const char *description,
 279                                      const void *callout_info,
 280                                      size_t callout_len);
 281
 282 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 283                                                   const char *description,
 284                                                   const void *callout_info,
 285                                                   size_t callout_len,
 286                                                   void *aux);
 287
 288 extern int wait_for_key_construction(struct key *key, bool intr);
 289
 290 extern int key_validate(const struct key *key);
 291
 292 extern key_ref_t key_create_or_update(key_ref_t keyring,
 293                                       const char *type,
 294                                       const char *description,
 295                                       const void *payload,
 296                                       size_t plen,
 297                                       key_perm_t perm,
 298                                       unsigned long flags);
 299
 300 extern int key_update(key_ref_t key,
 301                       const void *payload,
 302                       size_t plen);
 303
 304 extern int key_link(struct key *keyring,
 305                     struct key *key);
 306
 307 extern int key_unlink(struct key *keyring,
 308                       struct key *key);
 309
 310 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 311                                  const struct cred *cred,
 312                                  key_perm_t perm,
 313                                  unsigned long flags,
 314                                  struct key_restriction *restrict_link,
 315                                  struct key *dest);
 316
 317 extern int restrict_link_reject(struct key *keyring,
 318                                 const struct key_type *type,
 319                                 const union key_payload *payload,
 320                                 struct key *restriction_key);
 321
 322 extern int keyring_clear(struct key *keyring);
 323
 324 extern key_ref_t keyring_search(key_ref_t keyring,
 325                                 struct key_type *type,
 326                                 const char *description);
 327
 328 extern int keyring_add_key(struct key *keyring,
 329                            struct key *key);
 330
 331 extern int keyring_restrict(key_ref_t keyring, const char *type,
 332                             const char *restriction);
 333
 334 extern struct key *key_lookup(key_serial_t id);
 335
 336 static inline key_serial_t key_serial(const struct key *key)
 337 {
 338         return key ? key->serial : 0;
 339 }
 340
 341 extern void key_set_timeout(struct key *, unsigned);
 342
 343 /*
 344  * The permissions required on a key that we're looking up.
 345  */
 346 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 347 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 348 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 349 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 350 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 351 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 352 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 353
 354 /**
 355  * key_is_instantiated - Determine if a key has been positively instantiated
 356  * @key: The key to check.
 357  *
 358  * Return true if the specified key has been positively instantiated, false
 359  * otherwise.
 360  */
 361 static inline bool key_is_instantiated(const struct key *key)
 362 {
 363         return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 364                 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 365 }
 366
 367 #define dereference_key_rcu(KEY)                                        \
 368         (rcu_dereference((KEY)->payload.rcu_data0))
 369
 370 #define dereference_key_locked(KEY)                                     \
 371         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 372                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 373
 374 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 375 do {                                                                    \
 376         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 377 } while (0)
 378
 379 #ifdef CONFIG_SYSCTL
 380 extern struct ctl_table key_sysctls[];
 381 #endif
 382 /*
 383  * the userspace interface
 384  */
 385 extern int install_thread_keyring_to_cred(struct cred *cred);
 386 extern void key_fsuid_changed(struct task_struct *tsk);
 387 extern void key_fsgid_changed(struct task_struct *tsk);
 388 extern void key_init(void);
 389
 390 #else /* CONFIG_KEYS */
 391
 392 #define key_validate(k)                 0
 393 #define key_serial(k)                   0
 394 #define key_get(k)                      ({ NULL; })
 395 #define key_revoke(k)                   do { } while(0)
 396 #define key_invalidate(k)               do { } while(0)
 397 #define key_put(k)                      do { } while(0)
 398 #define key_ref_put(k)                  do { } while(0)
 399 #define make_key_ref(k, p)              NULL
 400 #define key_ref_to_ptr(k)               NULL
 401 #define is_key_possessed(k)             0
 402 #define key_fsuid_changed(t)            do { } while(0)
 403 #define key_fsgid_changed(t)            do { } while(0)
 404 #define key_init()                      do { } while(0)
 405
 406 #endif /* CONFIG_KEYS */
 407 #endif /* __KERNEL__ */
 408 #endif /* _LINUX_KEY_H */