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 #define KEY_FLAG_UID_KEYRING    11      /* set if key is a user or user session keyring */
 191
 192         /* the key type and key description string
 193          * - the desc is used to match a key against search criteria
 194          * - it should be a printable string
 195          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 196          */
 197         union {
 198                 struct keyring_index_key index_key;
 199                 struct {
 200                         struct key_type *type;          /* type of key */
 201                         char            *description;
 202                 };
 203         };
 204
 205         /* key data
 206          * - this is used to hold the data actually used in cryptography or
 207          *   whatever
 208          */
 209         union {
 210                 union key_payload payload;
 211                 struct {
 212                         /* Keyring bits */
 213                         struct list_head name_link;
 214                         struct assoc_array keys;
 215                 };
 216                 int reject_error;
 217         };
 218
 219         /* This is set on a keyring to restrict the addition of a link to a key
 220          * to it.  If this structure isn't provided then it is assumed that the
 221          * keyring is open to any addition.  It is ignored for non-keyring
 222          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 223          * or key_alloc().
 224          *
 225          * This is intended for use with rings of trusted keys whereby addition
 226          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 227          * overrides this, allowing the kernel to add extra keys without
 228          * restriction.
 229          */
 230         struct key_restriction *restrict_link;
 231 };
 232
 233 extern struct key *key_alloc(struct key_type *type,
 234                              const char *desc,
 235                              kuid_t uid, kgid_t gid,
 236                              const struct cred *cred,
 237                              key_perm_t perm,
 238                              unsigned long flags,
 239                              struct key_restriction *restrict_link);
 240
 241
 242 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 243 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 244 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 245 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 246 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 247 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 248
 249 extern void key_revoke(struct key *key);
 250 extern void key_invalidate(struct key *key);
 251 extern void key_put(struct key *key);
 252
 253 static inline struct key *__key_get(struct key *key)
 254 {
 255         refcount_inc(&key->usage);
 256         return key;
 257 }
 258
 259 static inline struct key *key_get(struct key *key)
 260 {
 261         return key ? __key_get(key) : key;
 262 }
 263
 264 static inline void key_ref_put(key_ref_t key_ref)
 265 {
 266         key_put(key_ref_to_ptr(key_ref));
 267 }
 268
 269 extern struct key *request_key(struct key_type *type,
 270                                const char *description,
 271                                const char *callout_info);
 272
 273 extern struct key *request_key_with_auxdata(struct key_type *type,
 274                                             const char *description,
 275                                             const void *callout_info,
 276                                             size_t callout_len,
 277                                             void *aux);
 278
 279 extern struct key *request_key_async(struct key_type *type,
 280                                      const char *description,
 281                                      const void *callout_info,
 282                                      size_t callout_len);
 283
 284 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 285                                                   const char *description,
 286                                                   const void *callout_info,
 287                                                   size_t callout_len,
 288                                                   void *aux);
 289
 290 extern int wait_for_key_construction(struct key *key, bool intr);
 291
 292 extern int key_validate(const struct key *key);
 293
 294 extern key_ref_t key_create_or_update(key_ref_t keyring,
 295                                       const char *type,
 296                                       const char *description,
 297                                       const void *payload,
 298                                       size_t plen,
 299                                       key_perm_t perm,
 300                                       unsigned long flags);
 301
 302 extern int key_update(key_ref_t key,
 303                       const void *payload,
 304                       size_t plen);
 305
 306 extern int key_link(struct key *keyring,
 307                     struct key *key);
 308
 309 extern int key_unlink(struct key *keyring,
 310                       struct key *key);
 311
 312 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 313                                  const struct cred *cred,
 314                                  key_perm_t perm,
 315                                  unsigned long flags,
 316                                  struct key_restriction *restrict_link,
 317                                  struct key *dest);
 318
 319 extern int restrict_link_reject(struct key *keyring,
 320                                 const struct key_type *type,
 321                                 const union key_payload *payload,
 322                                 struct key *restriction_key);
 323
 324 extern int keyring_clear(struct key *keyring);
 325
 326 extern key_ref_t keyring_search(key_ref_t keyring,
 327                                 struct key_type *type,
 328                                 const char *description);
 329
 330 extern int keyring_add_key(struct key *keyring,
 331                            struct key *key);
 332
 333 extern int keyring_restrict(key_ref_t keyring, const char *type,
 334                             const char *restriction);
 335
 336 extern struct key *key_lookup(key_serial_t id);
 337
 338 static inline key_serial_t key_serial(const struct key *key)
 339 {
 340         return key ? key->serial : 0;
 341 }
 342
 343 extern void key_set_timeout(struct key *, unsigned);
 344
 345 /*
 346  * The permissions required on a key that we're looking up.
 347  */
 348 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 349 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 350 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 351 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 352 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 353 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 354 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 355
 356 /**
 357  * key_is_instantiated - Determine if a key has been positively instantiated
 358  * @key: The key to check.
 359  *
 360  * Return true if the specified key has been positively instantiated, false
 361  * otherwise.
 362  */
 363 static inline bool key_is_instantiated(const struct key *key)
 364 {
 365         return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
 366                 !test_bit(KEY_FLAG_NEGATIVE, &key->flags);
 367 }
 368
 369 #define dereference_key_rcu(KEY)                                        \
 370         (rcu_dereference((KEY)->payload.rcu_data0))
 371
 372 #define dereference_key_locked(KEY)                                     \
 373         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 374                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 375
 376 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 377 do {                                                                    \
 378         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 379 } while (0)
 380
 381 #ifdef CONFIG_SYSCTL
 382 extern struct ctl_table key_sysctls[];
 383 #endif
 384 /*
 385  * the userspace interface
 386  */
 387 extern int install_thread_keyring_to_cred(struct cred *cred);
 388 extern void key_fsuid_changed(struct task_struct *tsk);
 389 extern void key_fsgid_changed(struct task_struct *tsk);
 390 extern void key_init(void);
 391
 392 #else /* CONFIG_KEYS */
 393
 394 #define key_validate(k)                 0
 395 #define key_serial(k)                   0
 396 #define key_get(k)                      ({ NULL; })
 397 #define key_revoke(k)                   do { } while(0)
 398 #define key_invalidate(k)               do { } while(0)
 399 #define key_put(k)                      do { } while(0)
 400 #define key_ref_put(k)                  do { } while(0)
 401 #define make_key_ref(k, p)              NULL
 402 #define key_ref_to_ptr(k)               NULL
 403 #define is_key_possessed(k)             0
 404 #define key_fsuid_changed(t)            do { } while(0)
 405 #define key_fsgid_changed(t)            do { } while(0)
 406 #define key_init()                      do { } while(0)
 407
 408 #endif /* CONFIG_KEYS */
 409 #endif /* __KERNEL__ */
 410 #endif /* _LINUX_KEY_H */