include/linux/key.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /* Authentication token and access key management
   3  *
   4  * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * See Documentation/security/keys/core.rst for information on keys/keyrings.
   8  */
   9
  10 #ifndef _LINUX_KEY_H
  11 #define _LINUX_KEY_H
  12
  13 #include <linux/types.h>
  14 #include <linux/list.h>
  15 #include <linux/rbtree.h>
  16 #include <linux/rcupdate.h>
  17 #include <linux/sysctl.h>
  18 #include <linux/rwsem.h>
  19 #include <linux/atomic.h>
  20 #include <linux/assoc_array.h>
  21 #include <linux/refcount.h>
  22 #include <linux/time64.h>
  23
  24 #ifdef __KERNEL__
  25 #include <linux/uidgid.h>
  26
  27 /* key handle serial number */
  28 typedef int32_t key_serial_t;
  29
  30 /* key handle permissions mask */
  31 typedef uint32_t key_perm_t;
  32
  33 struct key;
  34 struct net;
  35
  36 #ifdef CONFIG_KEYS
  37
  38 #undef KEY_DEBUGGING
  39
  40 #define KEY_POS_VIEW    0x01000000      /* possessor can view a key's attributes */
  41 #define KEY_POS_READ    0x02000000      /* possessor can read key payload / view keyring */
  42 #define KEY_POS_WRITE   0x04000000      /* possessor can update key payload / add link to keyring */
  43 #define KEY_POS_SEARCH  0x08000000      /* possessor can find a key in search / search a keyring */
  44 #define KEY_POS_LINK    0x10000000      /* possessor can create a link to a key/keyring */
  45 #define KEY_POS_SETATTR 0x20000000      /* possessor can set key attributes */
  46 #define KEY_POS_ALL     0x3f000000
  47
  48 #define KEY_USR_VIEW    0x00010000      /* user permissions... */
  49 #define KEY_USR_READ    0x00020000
  50 #define KEY_USR_WRITE   0x00040000
  51 #define KEY_USR_SEARCH  0x00080000
  52 #define KEY_USR_LINK    0x00100000
  53 #define KEY_USR_SETATTR 0x00200000
  54 #define KEY_USR_ALL     0x003f0000
  55
  56 #define KEY_GRP_VIEW    0x00000100      /* group permissions... */
  57 #define KEY_GRP_READ    0x00000200
  58 #define KEY_GRP_WRITE   0x00000400
  59 #define KEY_GRP_SEARCH  0x00000800
  60 #define KEY_GRP_LINK    0x00001000
  61 #define KEY_GRP_SETATTR 0x00002000
  62 #define KEY_GRP_ALL     0x00003f00
  63
  64 #define KEY_OTH_VIEW    0x00000001      /* third party permissions... */
  65 #define KEY_OTH_READ    0x00000002
  66 #define KEY_OTH_WRITE   0x00000004
  67 #define KEY_OTH_SEARCH  0x00000008
  68 #define KEY_OTH_LINK    0x00000010
  69 #define KEY_OTH_SETATTR 0x00000020
  70 #define KEY_OTH_ALL     0x0000003f
  71
  72 #define KEY_PERM_UNDEF  0xffffffff
  73
  74 struct seq_file;
  75 struct user_struct;
  76 struct signal_struct;
  77 struct cred;
  78
  79 struct key_type;
  80 struct key_owner;
  81 struct key_tag;
  82 struct keyring_list;
  83 struct keyring_name;
  84
  85 struct key_tag {
  86         struct rcu_head         rcu;
  87         refcount_t              usage;
  88         bool                    removed;        /* T when subject removed */
  89 };
  90
  91 struct keyring_index_key {
  92         /* [!] If this structure is altered, the union in struct key must change too! */
  93         unsigned long           hash;                   /* Hash value */
  94         union {
  95                 struct {
  96 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
  97                         u16     desc_len;
  98                         char    desc[sizeof(long) - 2]; /* First few chars of description */
  99 #else
 100                         char    desc[sizeof(long) - 2]; /* First few chars of description */
 101                         u16     desc_len;
 102 #endif
 103                 };
 104                 unsigned long x;
 105         };
 106         struct key_type         *type;
 107         struct key_tag          *domain_tag;    /* Domain of operation */
 108         const char              *description;
 109 };
 110
 111 union key_payload {
 112         void __rcu              *rcu_data0;
 113         void                    *data[4];
 114 };
 115
 116 /*****************************************************************************/
 117 /*
 118  * key reference with possession attribute handling
 119  *
 120  * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 121  * defined. This is because we abuse the bottom bit of the reference to carry a
 122  * flag to indicate whether the calling process possesses that key in one of
 123  * its keyrings.
 124  *
 125  * the key_ref_t has been made a separate type so that the compiler can reject
 126  * attempts to dereference it without proper conversion.
 127  *
 128  * the three functions are used to assemble and disassemble references
 129  */
 130 typedef struct __key_reference_with_attributes *key_ref_t;
 131
 132 static inline key_ref_t make_key_ref(const struct key *key,
 133                                      bool possession)
 134 {
 135         return (key_ref_t) ((unsigned long) key | possession);
 136 }
 137
 138 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
 139 {
 140         return (struct key *) ((unsigned long) key_ref & ~1UL);
 141 }
 142
 143 static inline bool is_key_possessed(const key_ref_t key_ref)
 144 {
 145         return (unsigned long) key_ref & 1UL;
 146 }
 147
 148 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
 149                                         const struct key_type *type,
 150                                         const union key_payload *payload,
 151                                         struct key *restriction_key);
 152
 153 struct key_restriction {
 154         key_restrict_link_func_t check;
 155         struct key *key;
 156         struct key_type *keytype;
 157 };
 158
 159 enum key_state {
 160         KEY_IS_UNINSTANTIATED,
 161         KEY_IS_POSITIVE,                /* Positively instantiated */
 162 };
 163
 164 /*****************************************************************************/
 165 /*
 166  * authentication token / access credential / keyring
 167  * - types of key include:
 168  *   - keyrings
 169  *   - disk encryption IDs
 170  *   - Kerberos TGTs and tickets
 171  */
 172 struct key {
 173         refcount_t              usage;          /* number of references */
 174         key_serial_t            serial;         /* key serial number */
 175         union {
 176                 struct list_head graveyard_link;
 177                 struct rb_node  serial_node;
 178         };
 179         struct rw_semaphore     sem;            /* change vs change sem */
 180         struct key_user         *user;          /* owner of this key */
 181         void                    *security;      /* security data for this key */
 182         union {
 183                 time64_t        expiry;         /* time at which key expires (or 0) */
 184                 time64_t        revoked_at;     /* time at which key was revoked */
 185         };
 186         time64_t                last_used_at;   /* last time used for LRU keyring discard */
 187         kuid_t                  uid;
 188         kgid_t                  gid;
 189         key_perm_t              perm;           /* access permissions */
 190         unsigned short          quotalen;       /* length added to quota */
 191         unsigned short          datalen;        /* payload data length
 192                                                  * - may not match RCU dereferenced payload
 193                                                  * - payload should contain own length
 194                                                  */
 195         short                   state;          /* Key state (+) or rejection error (-) */
 196
 197 #ifdef KEY_DEBUGGING
 198         unsigned                magic;
 199 #define KEY_DEBUG_MAGIC         0x18273645u
 200 #endif
 201
 202         unsigned long           flags;          /* status flags (change with bitops) */
 203 #define KEY_FLAG_DEAD           0       /* set if key type has been deleted */
 204 #define KEY_FLAG_REVOKED        1       /* set if key had been revoked */
 205 #define KEY_FLAG_IN_QUOTA       2       /* set if key consumes quota */
 206 #define KEY_FLAG_USER_CONSTRUCT 3       /* set if key is being constructed in userspace */
 207 #define KEY_FLAG_ROOT_CAN_CLEAR 4       /* set if key can be cleared by root without permission */
 208 #define KEY_FLAG_INVALIDATED    5       /* set if key has been invalidated */
 209 #define KEY_FLAG_BUILTIN        6       /* set if key is built in to the kernel */
 210 #define KEY_FLAG_ROOT_CAN_INVAL 7       /* set if key can be invalidated by root without permission */
 211 #define KEY_FLAG_KEEP           8       /* set if key should not be removed */
 212 #define KEY_FLAG_UID_KEYRING    9       /* set if key is a user or user session keyring */
 213
 214         /* the key type and key description string
 215          * - the desc is used to match a key against search criteria
 216          * - it should be a printable string
 217          * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
 218          */
 219         union {
 220                 struct keyring_index_key index_key;
 221                 struct {
 222                         unsigned long   hash;
 223                         unsigned long   len_desc;
 224                         struct key_type *type;          /* type of key */
 225                         struct key_tag  *domain_tag;    /* Domain of operation */
 226                         char            *description;
 227                 };
 228         };
 229
 230         /* key data
 231          * - this is used to hold the data actually used in cryptography or
 232          *   whatever
 233          */
 234         union {
 235                 union key_payload payload;
 236                 struct {
 237                         /* Keyring bits */
 238                         struct list_head name_link;
 239                         struct assoc_array keys;
 240                 };
 241         };
 242
 243         /* This is set on a keyring to restrict the addition of a link to a key
 244          * to it.  If this structure isn't provided then it is assumed that the
 245          * keyring is open to any addition.  It is ignored for non-keyring
 246          * keys. Only set this value using keyring_restrict(), keyring_alloc(),
 247          * or key_alloc().
 248          *
 249          * This is intended for use with rings of trusted keys whereby addition
 250          * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
 251          * overrides this, allowing the kernel to add extra keys without
 252          * restriction.
 253          */
 254         struct key_restriction *restrict_link;
 255 };
 256
 257 extern struct key *key_alloc(struct key_type *type,
 258                              const char *desc,
 259                              kuid_t uid, kgid_t gid,
 260                              const struct cred *cred,
 261                              key_perm_t perm,
 262                              unsigned long flags,
 263                              struct key_restriction *restrict_link);
 264
 265
 266 #define KEY_ALLOC_IN_QUOTA              0x0000  /* add to quota, reject if would overrun */
 267 #define KEY_ALLOC_QUOTA_OVERRUN         0x0001  /* add to quota, permit even if overrun */
 268 #define KEY_ALLOC_NOT_IN_QUOTA          0x0002  /* not in quota */
 269 #define KEY_ALLOC_BUILT_IN              0x0004  /* Key is built into kernel */
 270 #define KEY_ALLOC_BYPASS_RESTRICTION    0x0008  /* Override the check on restricted keyrings */
 271 #define KEY_ALLOC_UID_KEYRING           0x0010  /* allocating a user or user session keyring */
 272
 273 extern void key_revoke(struct key *key);
 274 extern void key_invalidate(struct key *key);
 275 extern void key_put(struct key *key);
 276 extern bool key_put_tag(struct key_tag *tag);
 277 extern void key_remove_domain(struct key_tag *domain_tag);
 278
 279 static inline struct key *__key_get(struct key *key)
 280 {
 281         refcount_inc(&key->usage);
 282         return key;
 283 }
 284
 285 static inline struct key *key_get(struct key *key)
 286 {
 287         return key ? __key_get(key) : key;
 288 }
 289
 290 static inline void key_ref_put(key_ref_t key_ref)
 291 {
 292         key_put(key_ref_to_ptr(key_ref));
 293 }
 294
 295 extern struct key *request_key_tag(struct key_type *type,
 296                                    const char *description,
 297                                    struct key_tag *domain_tag,
 298                                    const char *callout_info);
 299
 300 extern struct key *request_key_rcu(struct key_type *type,
 301                                    const char *description,
 302                                    struct key_tag *domain_tag);
 303
 304 extern struct key *request_key_with_auxdata(struct key_type *type,
 305                                             const char *description,
 306                                             struct key_tag *domain_tag,
 307                                             const void *callout_info,
 308                                             size_t callout_len,
 309                                             void *aux);
 310
 311 /**
 312  * request_key - Request a key and wait for construction
 313  * @type: Type of key.
 314  * @description: The searchable description of the key.
 315  * @callout_info: The data to pass to the instantiation upcall (or NULL).
 316  *
 317  * As for request_key_tag(), but with the default global domain tag.
 318  */
 319 static inline struct key *request_key(struct key_type *type,
 320                                       const char *description,
 321                                       const char *callout_info)
 322 {
 323         return request_key_tag(type, description, NULL, callout_info);
 324 }
 325
 326 #ifdef CONFIG_NET
 327 /*
 328  * request_key_net - Request a key for a net namespace and wait for construction
 329  * @type: Type of key.
 330  * @description: The searchable description of the key.
 331  * @net: The network namespace that is the key's domain of operation.
 332  * @callout_info: The data to pass to the instantiation upcall (or NULL).
 333  *
 334  * As for request_key() except that it does not add the returned key to a
 335  * keyring if found, new keys are always allocated in the user's quota, the
 336  * callout_info must be a NUL-terminated string and no auxiliary data can be
 337  * passed.  Only keys that operate the specified network namespace are used.
 338  *
 339  * Furthermore, it then works as wait_for_key_construction() to wait for the
 340  * completion of keys undergoing construction with a non-interruptible wait.
 341  */
 342 #define request_key_net(type, description, net, callout_info) \
 343         request_key_tag(type, description, net->key_domain, callout_info);
 344 #endif /* CONFIG_NET */
 345
 346 extern int wait_for_key_construction(struct key *key, bool intr);
 347
 348 extern int key_validate(const struct key *key);
 349
 350 extern key_ref_t key_create_or_update(key_ref_t keyring,
 351                                       const char *type,
 352                                       const char *description,
 353                                       const void *payload,
 354                                       size_t plen,
 355                                       key_perm_t perm,
 356                                       unsigned long flags);
 357
 358 extern int key_update(key_ref_t key,
 359                       const void *payload,
 360                       size_t plen);
 361
 362 extern int key_link(struct key *keyring,
 363                     struct key *key);
 364
 365 extern int key_move(struct key *key,
 366                     struct key *from_keyring,
 367                     struct key *to_keyring,
 368                     unsigned int flags);
 369
 370 extern int key_unlink(struct key *keyring,
 371                       struct key *key);
 372
 373 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 374                                  const struct cred *cred,
 375                                  key_perm_t perm,
 376                                  unsigned long flags,
 377                                  struct key_restriction *restrict_link,
 378                                  struct key *dest);
 379
 380 extern int restrict_link_reject(struct key *keyring,
 381                                 const struct key_type *type,
 382                                 const union key_payload *payload,
 383                                 struct key *restriction_key);
 384
 385 extern int keyring_clear(struct key *keyring);
 386
 387 extern key_ref_t keyring_search(key_ref_t keyring,
 388                                 struct key_type *type,
 389                                 const char *description,
 390                                 bool recurse);
 391
 392 extern int keyring_add_key(struct key *keyring,
 393                            struct key *key);
 394
 395 extern int keyring_restrict(key_ref_t keyring, const char *type,
 396                             const char *restriction);
 397
 398 extern struct key *key_lookup(key_serial_t id);
 399
 400 static inline key_serial_t key_serial(const struct key *key)
 401 {
 402         return key ? key->serial : 0;
 403 }
 404
 405 extern void key_set_timeout(struct key *, unsigned);
 406
 407 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 408                                  key_perm_t perm);
 409 extern void key_free_user_ns(struct user_namespace *);
 410
 411 /*
 412  * The permissions required on a key that we're looking up.
 413  */
 414 #define KEY_NEED_VIEW   0x01    /* Require permission to view attributes */
 415 #define KEY_NEED_READ   0x02    /* Require permission to read content */
 416 #define KEY_NEED_WRITE  0x04    /* Require permission to update / modify */
 417 #define KEY_NEED_SEARCH 0x08    /* Require permission to search (keyring) or find (key) */
 418 #define KEY_NEED_LINK   0x10    /* Require permission to link */
 419 #define KEY_NEED_SETATTR 0x20   /* Require permission to change attributes */
 420 #define KEY_NEED_ALL    0x3f    /* All the above permissions */
 421
 422 static inline short key_read_state(const struct key *key)
 423 {
 424         /* Barrier versus mark_key_instantiated(). */
 425         return smp_load_acquire(&key->state);
 426 }
 427
 428 /**
 429  * key_is_positive - Determine if a key has been positively instantiated
 430  * @key: The key to check.
 431  *
 432  * Return true if the specified key has been positively instantiated, false
 433  * otherwise.
 434  */
 435 static inline bool key_is_positive(const struct key *key)
 436 {
 437         return key_read_state(key) == KEY_IS_POSITIVE;
 438 }
 439
 440 static inline bool key_is_negative(const struct key *key)
 441 {
 442         return key_read_state(key) < 0;
 443 }
 444
 445 #define dereference_key_rcu(KEY)                                        \
 446         (rcu_dereference((KEY)->payload.rcu_data0))
 447
 448 #define dereference_key_locked(KEY)                                     \
 449         (rcu_dereference_protected((KEY)->payload.rcu_data0,            \
 450                                    rwsem_is_locked(&((struct key *)(KEY))->sem)))
 451
 452 #define rcu_assign_keypointer(KEY, PAYLOAD)                             \
 453 do {                                                                    \
 454         rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));        \
 455 } while (0)
 456
 457 #ifdef CONFIG_SYSCTL
 458 extern struct ctl_table key_sysctls[];
 459 #endif
 460 /*
 461  * the userspace interface
 462  */
 463 extern int install_thread_keyring_to_cred(struct cred *cred);
 464 extern void key_fsuid_changed(struct cred *new_cred);
 465 extern void key_fsgid_changed(struct cred *new_cred);
 466 extern void key_init(void);
 467
 468 #else /* CONFIG_KEYS */
 469
 470 #define key_validate(k)                 0
 471 #define key_serial(k)                   0
 472 #define key_get(k)                      ({ NULL; })
 473 #define key_revoke(k)                   do { } while(0)
 474 #define key_invalidate(k)               do { } while(0)
 475 #define key_put(k)                      do { } while(0)
 476 #define key_ref_put(k)                  do { } while(0)
 477 #define make_key_ref(k, p)              NULL
 478 #define key_ref_to_ptr(k)               NULL
 479 #define is_key_possessed(k)             0
 480 #define key_fsuid_changed(c)            do { } while(0)
 481 #define key_fsgid_changed(c)            do { } while(0)
 482 #define key_init()                      do { } while(0)
 483 #define key_free_user_ns(ns)            do { } while(0)
 484 #define key_remove_domain(d)            do { } while(0)
 485
 486 #endif /* CONFIG_KEYS */
 487 #endif /* __KERNEL__ */
 488 #endif /* _LINUX_KEY_H */