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 enum key_state {
 142         KEY_IS_UNINSTANTIATED,
 143         KEY_IS_POSITIVE,                /* Positively instantiated */
 144 };
 145
 146 /*****************************************************************************/
 147 /*
 148  * authentication token / access credential / keyring
 149  * - types of key include:
 150  *   - keyrings
 151  *   - disk encryption IDs
 152  *   - Kerberos TGTs and tickets
 153  */
 154 struct key {
 155         refcount_t              usage;          /* number of references */
 156         key_serial_t            serial;         /* key serial number */
 157         union {
 158                 struct list_head graveyard_link;
 159                 struct rb_node  serial_node;
 160         };
 161         struct rw_semaphore     sem;            /* change vs change sem */
 162         struct key_user         *user;          /* owner of this key */
 163         void                    *security;      /* security data for this key */
 164         union {
 165                 time_t          expiry;         /* time at which key expires (or 0) */
 166                 time_t          revoked_at;     /* time at which key was revoked */
 167         };
 168         time_t                  last_used_at;   /* last time used for LRU keyring discard */
 169         kuid_t                  uid;
 170         kgid_t                  gid;
 171         key_perm_t              perm;           /* access permissions */
 172         unsigned short          quotalen;       /* length added to quota */
 173         unsigned short          datalen;        /* payload data length
 174                                                  * - may not match RCU dereferenced payload
 175                                                  * - payload should contain own length
 176                                                  */
 177         short                   state;          /* Key state (+) or rejection error (-) */
 178
 179 #ifdef KEY_DEBUGGING
 180         unsigned                magic;
 181 #define KEY_DEBUG_MAGIC         0x18273645u
 182 #endif
 183
 184         unsigned long           flags;          /* status flags (change with bitops) */
 185 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
 186 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
 187 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
 188 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
 189 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
 190 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
 191 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
 192 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
 193 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
 194 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
 195
 196         /* the key type and key description string
 197          * - the desc is used to match a key against search criteria
 198          * - it should be a printable string
 199          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 200          */
 201         union {
 202                 struct keyring_index_key index_key;
 203                 struct {
 204                         struct key_type *type;          /* type of key */
 205                         char            *description;
 206                 };
 207         };
 208
 209         /* key data
 210          * - this is used to hold the data actually used in cryptography or
 211          *   whatever
 212          */
 213         union {
 214                 union key_payload payload;
 215                 struct {
 216                         /* Keyring bits */
 217                         struct list_head name_link;
 218                         struct assoc_array keys;
 219                 };
 220         };
 221
 222         /* This is set on a keyring to restrict the addition of a link to a key
 223          * to it.  If this structure isn't provided then it is assumed that the
 224          * keyring is open to any addition.  It is ignored for non-keyring
 225          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 226          * or key_alloc().
 227          *
 228          * This is intended for use with rings of trusted keys whereby addition
 229          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 230          * overrides this, allowing the kernel to add extra keys without
 231          * restriction.
 232          */
 233         struct key_restriction *restrict_link;
 234 };
 235
 236 extern struct key *key_alloc(struct key_type *type,
 237                              const char *desc,
 238                              kuid_t uid, kgid_t gid,
 239                              const struct cred *cred,
 240                              key_perm_t perm,
 241                              unsigned long flags,
 242                              struct key_restriction *restrict_link);
 243
 244
 245 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 246 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 247 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 248 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 249 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 250 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 251
 252 extern void key_revoke(struct key *key);
 253 extern void key_invalidate(struct key *key);
 254 extern void key_put(struct key *key);
 255
 256 static inline struct key *__key_get(struct key *key)
 257 {
 258         refcount_inc(&key->usage);
 259         return key;
 260 }
 261
 262 static inline struct key *key_get(struct key *key)
 263 {
 264         return key ? __key_get(key) : key;
 265 }
 266
 267 static inline void key_ref_put(key_ref_t key_ref)
 268 {
 269         key_put(key_ref_to_ptr(key_ref));
 270 }
 271
 272 extern struct key *request_key(struct key_type *type,
 273                                const char *description,
 274                                const char *callout_info);
 275
 276 extern struct key *request_key_with_auxdata(struct key_type *type,
 277                                             const char *description,
 278                                             const void *callout_info,
 279                                             size_t callout_len,
 280                                             void *aux);
 281
 282 extern struct key *request_key_async(struct key_type *type,
 283                                      const char *description,
 284                                      const void *callout_info,
 285                                      size_t callout_len);
 286
 287 extern struct key *request_key_async_with_auxdata(struct key_type *type,
 288                                                   const char *description,
 289                                                   const void *callout_info,
 290                                                   size_t callout_len,
 291                                                   void *aux);
 292
 293 extern int wait_for_key_construction(struct key *key, bool intr);
 294
 295 extern int key_validate(const struct key *key);
 296
 297 extern key_ref_t key_create_or_update(key_ref_t keyring,
 298                                       const char *type,
 299                                       const char *description,
 300                                       const void *payload,
 301                                       size_t plen,
 302                                       key_perm_t perm,
 303                                       unsigned long flags);
 304
 305 extern int key_update(key_ref_t key,
 306                       const void *payload,
 307                       size_t plen);
 308
 309 extern int key_link(struct key *keyring,
 310                     struct key *key);
 311
 312 extern int key_unlink(struct key *keyring,
 313                       struct key *key);
 314
 315 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 316                                  const struct cred *cred,
 317                                  key_perm_t perm,
 318                                  unsigned long flags,
 319                                  struct key_restriction *restrict_link,
 320                                  struct key *dest);
 321
 322 extern int restrict_link_reject(struct key *keyring,
 323                                 const struct key_type *type,
 324                                 const union key_payload *payload,
 325                                 struct key *restriction_key);
 326
 327 extern int keyring_clear(struct key *keyring);
 328
 329 extern key_ref_t keyring_search(key_ref_t keyring,
 330                                 struct key_type *type,
 331                                 const char *description);
 332
 333 extern int keyring_add_key(struct key *keyring,
 334                            struct key *key);
 335
 336 extern int keyring_restrict(key_ref_t keyring, const char *type,
 337                             const char *restriction);
 338
 339 extern struct key *key_lookup(key_serial_t id);
 340
 341 static inline key_serial_t key_serial(const struct key *key)
 342 {
 343         return key ? key->serial : 0;
 344 }
 345
 346 extern void key_set_timeout(struct key *, unsigned);
 347
 348 /*
 349  * The permissions required on a key that we're looking up.
 350  */
 351 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 352 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 353 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 354 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 355 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 356 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 357 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 358
 359 static inline short key_read_state(const struct key *key)
 360 {
 361         /* Barrier versus mark_key_instantiated(). */
 362         return smp_load_acquire(&key->state);
 363 }
 364
 365 /**
 366  * key_is_positive - Determine if a key has been positively instantiated
 367  * @key: The key to check.
 368  *
 369  * Return true if the specified key has been positively instantiated, false
 370  * otherwise.
 371  */
 372 static inline bool key_is_positive(const struct key *key)
 373 {
 374         return key_read_state(key) == KEY_IS_POSITIVE;
 375 }
 376
 377 static inline bool key_is_negative(const struct key *key)
 378 {
 379         return key_read_state(key) < 0;
 380 }
 381
 382 #define dereference_key_rcu(KEY)                                        \
 383         (rcu_dereference((KEY)->payload.rcu_data0))
 384
 385 #define dereference_key_locked(KEY)                                     \
 386         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 387                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 388
 389 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 390 do {                                                                    \
 391         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 392 } while (0)
 393
 394 #ifdef CONFIG_SYSCTL
 395 extern struct ctl_table key_sysctls[];
 396 #endif
 397 /*
 398  * the userspace interface
 399  */
 400 extern int install_thread_keyring_to_cred(struct cred *cred);
 401 extern void key_fsuid_changed(struct task_struct *tsk);
 402 extern void key_fsgid_changed(struct task_struct *tsk);
 403 extern void key_init(void);
 404
 405 #else /* CONFIG_KEYS */
 406
 407 #define key_validate(k)                 0
 408 #define key_serial(k)                   0
 409 #define key_get(k)                      ({ NULL; })
 410 #define key_revoke(k)                   do { } while(0)
 411 #define key_invalidate(k)               do { } while(0)
 412 #define key_put(k)                      do { } while(0)
 413 #define key_ref_put(k)                  do { } while(0)
 414 #define make_key_ref(k, p)              NULL
 415 #define key_ref_to_ptr(k)               NULL
 416 #define is_key_possessed(k)             0
 417 #define key_fsuid_changed(t)            do { } while(0)
 418 #define key_fsgid_changed(t)            do { } while(0)
 419 #define key_init()                      do { } while(0)
 420
 421 #endif /* CONFIG_KEYS */
 422 #endif /* __KERNEL__ */
 423 #endif /* _LINUX_KEY_H */