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 #include <linux/time64.h>
  28
  29 #ifdef __KERNEL__
  30 #include <linux/uidgid.h>
  31
  32 /* key handle serial number */
  33 typedef int32_t key_serial_t;
  34
  35 /* key handle permissions mask */
  36 typedef uint32_t key_perm_t;
  37
  38 struct key;
  39
  40 #ifdef CONFIG_KEYS
  41
  42 #undef KEY_DEBUGGING
  43
  44 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  45 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  46 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  47 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  48 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  49 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  50 #define KEY_POS_ALL     0x3f000000
  51
  52 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  53 #define KEY_USR_READ    0x00020000
  54 #define KEY_USR_WRITE   0x00040000
  55 #define KEY_USR_SEARCH  0x00080000
  56 #define KEY_USR_LINK    0x00100000
  57 #define KEY_USR_SETATTR 0x00200000
  58 #define KEY_USR_ALL     0x003f0000
  59
  60 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  61 #define KEY_GRP_READ    0x00000200
  62 #define KEY_GRP_WRITE   0x00000400
  63 #define KEY_GRP_SEARCH  0x00000800
  64 #define KEY_GRP_LINK    0x00001000
  65 #define KEY_GRP_SETATTR 0x00002000
  66 #define KEY_GRP_ALL     0x00003f00
  67
  68 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  69 #define KEY_OTH_READ    0x00000002
  70 #define KEY_OTH_WRITE   0x00000004
  71 #define KEY_OTH_SEARCH  0x00000008
  72 #define KEY_OTH_LINK    0x00000010
  73 #define KEY_OTH_SETATTR 0x00000020
  74 #define KEY_OTH_ALL     0x0000003f
  75
  76 #define KEY_PERM_UNDEF  0xffffffff
  77
  78 struct seq_file;
  79 struct user_struct;
  80 struct signal_struct;
  81 struct cred;
  82
  83 struct key_type;
  84 struct key_owner;
  85 struct keyring_list;
  86 struct keyring_name;
  87
  88 struct keyring_index_key {
  89         union {
  90                 struct {
  91 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
  92                         u8      desc_len;
  93                         char    desc[sizeof(long) - 1]; /* First few chars of description */
  94 #else
  95                         char    desc[sizeof(long) - 1]; /* First few chars of description */
  96                         u8      desc_len;
  97 #endif
  98                 };
  99                 unsigned long x;
 100         };
 101         struct key_type         *type;
 102         const char              *description;
 103 };
 104
 105 union key_payload {
 106         void __rcu              *rcu_data0;
 107         void                    *data[4];
 108 };
 109
 110 /*****************************************************************************/
 111 /*
 112  * key reference with possession attribute handling
 113  *
 114  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 115  * defined. This is because we abuse the bottom bit of the reference to carry a
 116  * flag to indicate whether the calling process possesses that key in one of
 117  * its keyrings.
 118  *
 119  * the key_ref_t has been made a separate type so that the compiler can reject
 120  * attempts to dereference it without proper conversion.
 121  *
 122  * the three functions are used to assemble and disassemble references
 123  */
 124 typedef struct __key_reference_with_attributes *key_ref_t;
 125
 126 static inline key_ref_t make_key_ref(const struct key *key,
 127                                      bool possession)
 128 {
 129         return (key_ref_t) ((unsigned long) key | possession);
 130 }
 131
 132 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 133 {
 134         return (struct key *) ((unsigned long) key_ref & ~1UL);
 135 }
 136
 137 static inline bool is_key_possessed(const key_ref_t key_ref)
 138 {
 139         return (unsigned long) key_ref & 1UL;
 140 }
 141
 142 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 143                                         const struct key_type *type,
 144                                         const union key_payload *payload,
 145                                         struct key *restriction_key);
 146
 147 struct key_restriction {
 148         key_restrict_link_func_t check;
 149         struct key *key;
 150         struct key_type *keytype;
 151 };
 152
 153 enum key_state {
 154         KEY_IS_UNINSTANTIATED,
 155         KEY_IS_POSITIVE,                /* Positively instantiated */
 156 };
 157
 158 /*****************************************************************************/
 159 /*
 160  * authentication token / access credential / keyring
 161  * - types of key include:
 162  *   - keyrings
 163  *   - disk encryption IDs
 164  *   - Kerberos TGTs and tickets
 165  */
 166 struct key {
 167         refcount_t              usage;          /* number of references */
 168         key_serial_t            serial;         /* key serial number */
 169         union {
 170                 struct list_head graveyard_link;
 171                 struct rb_node  serial_node;
 172         };
 173         struct rw_semaphore     sem;            /* change vs change sem */
 174         struct key_user         *user;          /* owner of this key */
 175         void                    *security;      /* security data for this key */
 176         union {
 177                 time64_t        expiry;         /* time at which key expires (or 0) */
 178                 time64_t        revoked_at;     /* time at which key was revoked */
 179         };
 180         time64_t                last_used_at;   /* last time used for LRU keyring discard */
 181         kuid_t                  uid;
 182         kgid_t                  gid;
 183         key_perm_t              perm;           /* access permissions */
 184         unsigned short          quotalen;       /* length added to quota */
 185         unsigned short          datalen;        /* payload data length
 186                                                  * - may not match RCU dereferenced payload
 187                                                  * - payload should contain own length
 188                                                  */
 189         short                   state;          /* Key state (+) or rejection error (-) */
 190
 191 #ifdef KEY_DEBUGGING
 192         unsigned                magic;
 193 #define KEY_DEBUG_MAGIC         0x18273645u
 194 #endif
 195
 196         unsigned long           flags;          /* status flags (change with bitops) */
 197 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
 198 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
 199 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
 200 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
 201 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
 202 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
 203 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
 204 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
 205 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
 206 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
 207
 208         /* the key type and key description string
 209          * - the desc is used to match a key against search criteria
 210          * - it should be a printable string
 211          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 212          */
 213         union {
 214                 struct keyring_index_key index_key;
 215                 struct {
 216                         unsigned long   len_desc;
 217                         struct key_type *type;          /* type of key */
 218                         char            *description;
 219                 };
 220         };
 221
 222         /* key data
 223          * - this is used to hold the data actually used in cryptography or
 224          *   whatever
 225          */
 226         union {
 227                 union key_payload payload;
 228                 struct {
 229                         /* Keyring bits */
 230                         struct list_head name_link;
 231                         struct assoc_array keys;
 232                 };
 233         };
 234
 235         /* This is set on a keyring to restrict the addition of a link to a key
 236          * to it.  If this structure isn't provided then it is assumed that the
 237          * keyring is open to any addition.  It is ignored for non-keyring
 238          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 239          * or key_alloc().
 240          *
 241          * This is intended for use with rings of trusted keys whereby addition
 242          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 243          * overrides this, allowing the kernel to add extra keys without
 244          * restriction.
 245          */
 246         struct key_restriction *restrict_link;
 247 };
 248
 249 extern struct key *key_alloc(struct key_type *type,
 250                              const char *desc,
 251                              kuid_t uid, kgid_t gid,
 252                              const struct cred *cred,
 253                              key_perm_t perm,
 254                              unsigned long flags,
 255                              struct key_restriction *restrict_link);
 256
 257
 258 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 259 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 260 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 261 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 262 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 263 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 264
 265 extern void key_revoke(struct key *key);
 266 extern void key_invalidate(struct key *key);
 267 extern void key_put(struct key *key);
 268
 269 static inline struct key *__key_get(struct key *key)
 270 {
 271         refcount_inc(&key->usage);
 272         return key;
 273 }
 274
 275 static inline struct key *key_get(struct key *key)
 276 {
 277         return key ? __key_get(key) : key;
 278 }
 279
 280 static inline void key_ref_put(key_ref_t key_ref)
 281 {
 282         key_put(key_ref_to_ptr(key_ref));
 283 }
 284
 285 extern struct key *request_key(struct key_type *type,
 286                                const char *description,
 287                                const char *callout_info);
 288
 289 extern struct key *request_key_rcu(struct key_type *type,
 290                                    const char *description);
 291
 292 extern struct key *request_key_with_auxdata(struct key_type *type,
 293                                             const char *description,
 294                                             const void *callout_info,
 295                                             size_t callout_len,
 296                                             void *aux);
 297
 298 extern int wait_for_key_construction(struct key *key, bool intr);
 299
 300 extern int key_validate(const struct key *key);
 301
 302 extern key_ref_t key_create_or_update(key_ref_t keyring,
 303                                       const char *type,
 304                                       const char *description,
 305                                       const void *payload,
 306                                       size_t plen,
 307                                       key_perm_t perm,
 308                                       unsigned long flags);
 309
 310 extern int key_update(key_ref_t key,
 311                       const void *payload,
 312                       size_t plen);
 313
 314 extern int key_link(struct key *keyring,
 315                     struct key *key);
 316
 317 extern int key_move(struct key *key,
 318                     struct key *from_keyring,
 319                     struct key *to_keyring,
 320                     unsigned int flags);
 321
 322 extern int key_unlink(struct key *keyring,
 323                       struct key *key);
 324
 325 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 326                                  const struct cred *cred,
 327                                  key_perm_t perm,
 328                                  unsigned long flags,
 329                                  struct key_restriction *restrict_link,
 330                                  struct key *dest);
 331
 332 extern int restrict_link_reject(struct key *keyring,
 333                                 const struct key_type *type,
 334                                 const union key_payload *payload,
 335                                 struct key *restriction_key);
 336
 337 extern int keyring_clear(struct key *keyring);
 338
 339 extern key_ref_t keyring_search(key_ref_t keyring,
 340                                 struct key_type *type,
 341                                 const char *description);
 342
 343 extern int keyring_add_key(struct key *keyring,
 344                            struct key *key);
 345
 346 extern int keyring_restrict(key_ref_t keyring, const char *type,
 347                             const char *restriction);
 348
 349 extern struct key *key_lookup(key_serial_t id);
 350
 351 static inline key_serial_t key_serial(const struct key *key)
 352 {
 353         return key ? key->serial : 0;
 354 }
 355
 356 extern void key_set_timeout(struct key *, unsigned);
 357
 358 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 359                                  key_perm_t perm);
 360
 361 /*
 362  * The permissions required on a key that we're looking up.
 363  */
 364 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 365 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 366 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 367 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 368 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 369 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 370 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 371
 372 static inline short key_read_state(const struct key *key)
 373 {
 374         /* Barrier versus mark_key_instantiated(). */
 375         return smp_load_acquire(&key->state);
 376 }
 377
 378 /**
 379  * key_is_positive - Determine if a key has been positively instantiated
 380  * @key: The key to check.
 381  *
 382  * Return true if the specified key has been positively instantiated, false
 383  * otherwise.
 384  */
 385 static inline bool key_is_positive(const struct key *key)
 386 {
 387         return key_read_state(key) == KEY_IS_POSITIVE;
 388 }
 389
 390 static inline bool key_is_negative(const struct key *key)
 391 {
 392         return key_read_state(key) < 0;
 393 }
 394
 395 #define dereference_key_rcu(KEY)                                        \
 396         (rcu_dereference((KEY)->payload.rcu_data0))
 397
 398 #define dereference_key_locked(KEY)                                     \
 399         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 400                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 401
 402 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 403 do {                                                                    \
 404         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 405 } while (0)
 406
 407 #ifdef CONFIG_SYSCTL
 408 extern struct ctl_table key_sysctls[];
 409 #endif
 410 /*
 411  * the userspace interface
 412  */
 413 extern int install_thread_keyring_to_cred(struct cred *cred);
 414 extern void key_fsuid_changed(struct cred *new_cred);
 415 extern void key_fsgid_changed(struct cred *new_cred);
 416 extern void key_init(void);
 417
 418 #else /* CONFIG_KEYS */
 419
 420 #define key_validate(k)                 0
 421 #define key_serial(k)                   0
 422 #define key_get(k)                      ({ NULL; })
 423 #define key_revoke(k)                   do { } while(0)
 424 #define key_invalidate(k)               do { } while(0)
 425 #define key_put(k)                      do { } while(0)
 426 #define key_ref_put(k)                  do { } while(0)
 427 #define make_key_ref(k, p)              NULL
 428 #define key_ref_to_ptr(k)               NULL
 429 #define is_key_possessed(k)             0
 430 #define key_fsuid_changed(c)            do { } while(0)
 431 #define key_fsgid_changed(c)            do { } while(0)
 432 #define key_init()                      do { } while(0)
 433
 434 #endif /* CONFIG_KEYS */
 435 #endif /* __KERNEL__ */
 436 #endif /* _LINUX_KEY_H */