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 /* 75 * The permissions required on a key that we're looking up. 76 */ 77 enum key_need_perm { 78 KEY_NEED_UNSPECIFIED, /* Needed permission unspecified */ 79 KEY_NEED_VIEW, /* Require permission to view attributes */ 80 KEY_NEED_READ, /* Require permission to read content */ 81 KEY_NEED_WRITE, /* Require permission to update / modify */ 82 KEY_NEED_SEARCH, /* Require permission to search (keyring) or find (key) */ 83 KEY_NEED_LINK, /* Require permission to link */ 84 KEY_NEED_SETATTR, /* Require permission to change attributes */ 85 KEY_NEED_UNLINK, /* Require permission to unlink key */ 86 KEY_SYSADMIN_OVERRIDE, /* Special: override by CAP_SYS_ADMIN */ 87 KEY_AUTHTOKEN_OVERRIDE, /* Special: override by possession of auth token */ 88 KEY_DEFER_PERM_CHECK, /* Special: permission check is deferred */ 89 }; 90 91 enum key_lookup_flag { 92 KEY_LOOKUP_CREATE = 0x01, 93 KEY_LOOKUP_PARTIAL = 0x02, 94 KEY_LOOKUP_ALL = (KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL), 95 }; 96 97 struct seq_file; 98 struct user_struct; 99 struct signal_struct; 100 struct cred; 101 102 struct key_type; 103 struct key_owner; 104 struct key_tag; 105 struct keyring_list; 106 struct keyring_name; 107 108 struct key_tag { 109 struct rcu_head rcu; 110 refcount_t usage; 111 bool removed; /* T when subject removed */ 112 }; 113 114 struct keyring_index_key { 115 /* [!] If this structure is altered, the union in struct key must change too! */ 116 unsigned long hash; /* Hash value */ 117 union { 118 struct { 119 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */ 120 u16 desc_len; 121 char desc[sizeof(long) - 2]; /* First few chars of description */ 122 #else 123 char desc[sizeof(long) - 2]; /* First few chars of description */ 124 u16 desc_len; 125 #endif 126 }; 127 unsigned long x; 128 }; 129 struct key_type *type; 130 struct key_tag *domain_tag; /* Domain of operation */ 131 const char *description; 132 }; 133 134 union key_payload { 135 void __rcu *rcu_data0; 136 void *data[4]; 137 }; 138 139 /*****************************************************************************/ 140 /* 141 * key reference with possession attribute handling 142 * 143 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually 144 * defined. This is because we abuse the bottom bit of the reference to carry a 145 * flag to indicate whether the calling process possesses that key in one of 146 * its keyrings. 147 * 148 * the key_ref_t has been made a separate type so that the compiler can reject 149 * attempts to dereference it without proper conversion. 150 * 151 * the three functions are used to assemble and disassemble references 152 */ 153 typedef struct __key_reference_with_attributes *key_ref_t; 154 155 static inline key_ref_t make_key_ref(const struct key *key, 156 bool possession) 157 { 158 return (key_ref_t) ((unsigned long) key | possession); 159 } 160 161 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref) 162 { 163 return (struct key *) ((unsigned long) key_ref & ~1UL); 164 } 165 166 static inline bool is_key_possessed(const key_ref_t key_ref) 167 { 168 return (unsigned long) key_ref & 1UL; 169 } 170 171 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring, 172 const struct key_type *type, 173 const union key_payload *payload, 174 struct key *restriction_key); 175 176 struct key_restriction { 177 key_restrict_link_func_t check; 178 struct key *key; 179 struct key_type *keytype; 180 }; 181 182 enum key_state { 183 KEY_IS_UNINSTANTIATED, 184 KEY_IS_POSITIVE, /* Positively instantiated */ 185 }; 186 187 /*****************************************************************************/ 188 /* 189 * authentication token / access credential / keyring 190 * - types of key include: 191 * - keyrings 192 * - disk encryption IDs 193 * - Kerberos TGTs and tickets 194 */ 195 struct key { 196 refcount_t usage; /* number of references */ 197 key_serial_t serial; /* key serial number */ 198 union { 199 struct list_head graveyard_link; 200 struct rb_node serial_node; 201 }; 202 #ifdef CONFIG_KEY_NOTIFICATIONS 203 struct watch_list *watchers; /* Entities watching this key for changes */ 204 #endif 205 struct rw_semaphore sem; /* change vs change sem */ 206 struct key_user *user; /* owner of this key */ 207 void *security; /* security data for this key */ 208 union { 209 time64_t expiry; /* time at which key expires (or 0) */ 210 time64_t revoked_at; /* time at which key was revoked */ 211 }; 212 time64_t last_used_at; /* last time used for LRU keyring discard */ 213 kuid_t uid; 214 kgid_t gid; 215 key_perm_t perm; /* access permissions */ 216 unsigned short quotalen; /* length added to quota */ 217 unsigned short datalen; /* payload data length 218 * - may not match RCU dereferenced payload 219 * - payload should contain own length 220 */ 221 short state; /* Key state (+) or rejection error (-) */ 222 223 #ifdef KEY_DEBUGGING 224 unsigned magic; 225 #define KEY_DEBUG_MAGIC 0x18273645u 226 #endif 227 228 unsigned long flags; /* status flags (change with bitops) */ 229 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */ 230 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */ 231 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */ 232 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */ 233 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */ 234 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */ 235 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */ 236 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */ 237 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */ 238 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */ 239 240 /* the key type and key description string 241 * - the desc is used to match a key against search criteria 242 * - it should be a printable string 243 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM" 244 */ 245 union { 246 struct keyring_index_key index_key; 247 struct { 248 unsigned long hash; 249 unsigned long len_desc; 250 struct key_type *type; /* type of key */ 251 struct key_tag *domain_tag; /* Domain of operation */ 252 char *description; 253 }; 254 }; 255 256 /* key data 257 * - this is used to hold the data actually used in cryptography or 258 * whatever 259 */ 260 union { 261 union key_payload payload; 262 struct { 263 /* Keyring bits */ 264 struct list_head name_link; 265 struct assoc_array keys; 266 }; 267 }; 268 269 /* This is set on a keyring to restrict the addition of a link to a key 270 * to it. If this structure isn't provided then it is assumed that the 271 * keyring is open to any addition. It is ignored for non-keyring 272 * keys. Only set this value using keyring_restrict(), keyring_alloc(), 273 * or key_alloc(). 274 * 275 * This is intended for use with rings of trusted keys whereby addition 276 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION 277 * overrides this, allowing the kernel to add extra keys without 278 * restriction. 279 */ 280 struct key_restriction *restrict_link; 281 }; 282 283 extern struct key *key_alloc(struct key_type *type, 284 const char *desc, 285 kuid_t uid, kgid_t gid, 286 const struct cred *cred, 287 key_perm_t perm, 288 unsigned long flags, 289 struct key_restriction *restrict_link); 290 291 292 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ 293 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ 294 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ 295 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ 296 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ 297 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ 298 #define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */ 299 300 extern void key_revoke(struct key *key); 301 extern void key_invalidate(struct key *key); 302 extern void key_put(struct key *key); 303 extern bool key_put_tag(struct key_tag *tag); 304 extern void key_remove_domain(struct key_tag *domain_tag); 305 306 static inline struct key *__key_get(struct key *key) 307 { 308 refcount_inc(&key->usage); 309 return key; 310 } 311 312 static inline struct key *key_get(struct key *key) 313 { 314 return key ? __key_get(key) : key; 315 } 316 317 static inline void key_ref_put(key_ref_t key_ref) 318 { 319 key_put(key_ref_to_ptr(key_ref)); 320 } 321 322 extern struct key *request_key_tag(struct key_type *type, 323 const char *description, 324 struct key_tag *domain_tag, 325 const char *callout_info); 326 327 extern struct key *request_key_rcu(struct key_type *type, 328 const char *description, 329 struct key_tag *domain_tag); 330 331 extern struct key *request_key_with_auxdata(struct key_type *type, 332 const char *description, 333 struct key_tag *domain_tag, 334 const void *callout_info, 335 size_t callout_len, 336 void *aux); 337 338 /** 339 * request_key - Request a key and wait for construction 340 * @type: Type of key. 341 * @description: The searchable description of the key. 342 * @callout_info: The data to pass to the instantiation upcall (or NULL). 343 * 344 * As for request_key_tag(), but with the default global domain tag. 345 */ 346 static inline struct key *request_key(struct key_type *type, 347 const char *description, 348 const char *callout_info) 349 { 350 return request_key_tag(type, description, NULL, callout_info); 351 } 352 353 #ifdef CONFIG_NET 354 /** 355 * request_key_net - Request a key for a net namespace and wait for construction 356 * @type: Type of key. 357 * @description: The searchable description of the key. 358 * @net: The network namespace that is the key's domain of operation. 359 * @callout_info: The data to pass to the instantiation upcall (or NULL). 360 * 361 * As for request_key() except that it does not add the returned key to a 362 * keyring if found, new keys are always allocated in the user's quota, the 363 * callout_info must be a NUL-terminated string and no auxiliary data can be 364 * passed. Only keys that operate the specified network namespace are used. 365 * 366 * Furthermore, it then works as wait_for_key_construction() to wait for the 367 * completion of keys undergoing construction with a non-interruptible wait. 368 */ 369 #define request_key_net(type, description, net, callout_info) \ 370 request_key_tag(type, description, net->key_domain, callout_info) 371 372 /** 373 * request_key_net_rcu - Request a key for a net namespace under RCU conditions 374 * @type: Type of key. 375 * @description: The searchable description of the key. 376 * @net: The network namespace that is the key's domain of operation. 377 * 378 * As for request_key_rcu() except that only keys that operate the specified 379 * network namespace are used. 380 */ 381 #define request_key_net_rcu(type, description, net) \ 382 request_key_rcu(type, description, net->key_domain) 383 #endif /* CONFIG_NET */ 384 385 extern int wait_for_key_construction(struct key *key, bool intr); 386 387 extern int key_validate(const struct key *key); 388 389 extern key_ref_t key_create_or_update(key_ref_t keyring, 390 const char *type, 391 const char *description, 392 const void *payload, 393 size_t plen, 394 key_perm_t perm, 395 unsigned long flags); 396 397 extern int key_update(key_ref_t key, 398 const void *payload, 399 size_t plen); 400 401 extern int key_link(struct key *keyring, 402 struct key *key); 403 404 extern int key_move(struct key *key, 405 struct key *from_keyring, 406 struct key *to_keyring, 407 unsigned int flags); 408 409 extern int key_unlink(struct key *keyring, 410 struct key *key); 411 412 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 413 const struct cred *cred, 414 key_perm_t perm, 415 unsigned long flags, 416 struct key_restriction *restrict_link, 417 struct key *dest); 418 419 extern int restrict_link_reject(struct key *keyring, 420 const struct key_type *type, 421 const union key_payload *payload, 422 struct key *restriction_key); 423 424 extern int keyring_clear(struct key *keyring); 425 426 extern key_ref_t keyring_search(key_ref_t keyring, 427 struct key_type *type, 428 const char *description, 429 bool recurse); 430 431 extern int keyring_add_key(struct key *keyring, 432 struct key *key); 433 434 extern int keyring_restrict(key_ref_t keyring, const char *type, 435 const char *restriction); 436 437 extern struct key *key_lookup(key_serial_t id); 438 439 static inline key_serial_t key_serial(const struct key *key) 440 { 441 return key ? key->serial : 0; 442 } 443 444 extern void key_set_timeout(struct key *, unsigned); 445 446 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags, 447 enum key_need_perm need_perm); 448 extern void key_free_user_ns(struct user_namespace *); 449 450 static inline short key_read_state(const struct key *key) 451 { 452 /* Barrier versus mark_key_instantiated(). */ 453 return smp_load_acquire(&key->state); 454 } 455 456 /** 457 * key_is_positive - Determine if a key has been positively instantiated 458 * @key: The key to check. 459 * 460 * Return true if the specified key has been positively instantiated, false 461 * otherwise. 462 */ 463 static inline bool key_is_positive(const struct key *key) 464 { 465 return key_read_state(key) == KEY_IS_POSITIVE; 466 } 467 468 static inline bool key_is_negative(const struct key *key) 469 { 470 return key_read_state(key) < 0; 471 } 472 473 #define dereference_key_rcu(KEY) \ 474 (rcu_dereference((KEY)->payload.rcu_data0)) 475 476 #define dereference_key_locked(KEY) \ 477 (rcu_dereference_protected((KEY)->payload.rcu_data0, \ 478 rwsem_is_locked(&((struct key *)(KEY))->sem))) 479 480 #define rcu_assign_keypointer(KEY, PAYLOAD) \ 481 do { \ 482 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ 483 } while (0) 484 485 #ifdef CONFIG_SYSCTL 486 extern struct ctl_table key_sysctls[]; 487 #endif 488 /* 489 * the userspace interface 490 */ 491 extern int install_thread_keyring_to_cred(struct cred *cred); 492 extern void key_fsuid_changed(struct cred *new_cred); 493 extern void key_fsgid_changed(struct cred *new_cred); 494 extern void key_init(void); 495 496 #else /* CONFIG_KEYS */ 497 498 #define key_validate(k) 0 499 #define key_serial(k) 0 500 #define key_get(k) ({ NULL; }) 501 #define key_revoke(k) do { } while(0) 502 #define key_invalidate(k) do { } while(0) 503 #define key_put(k) do { } while(0) 504 #define key_ref_put(k) do { } while(0) 505 #define make_key_ref(k, p) NULL 506 #define key_ref_to_ptr(k) NULL 507 #define is_key_possessed(k) 0 508 #define key_fsuid_changed(c) do { } while(0) 509 #define key_fsgid_changed(c) do { } while(0) 510 #define key_init() do { } while(0) 511 #define key_free_user_ns(ns) do { } while(0) 512 #define key_remove_domain(d) do { } while(0) 513 514 #endif /* CONFIG_KEYS */ 515 #endif /* __KERNEL__ */ 516 #endif /* _LINUX_KEY_H */ 517