1 /* Authentication token and access key management 2 * 3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells ([email protected]) 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 key_tag; 86 struct keyring_list; 87 struct keyring_name; 88 89 struct key_tag { 90 struct rcu_head rcu; 91 refcount_t usage; 92 bool removed; /* T when subject removed */ 93 }; 94 95 struct keyring_index_key { 96 /* [!] If this structure is altered, the union in struct key must change too! */ 97 unsigned long hash; /* Hash value */ 98 union { 99 struct { 100 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */ 101 u8 desc_len; 102 char desc[sizeof(long) - 1]; /* First few chars of description */ 103 #else 104 char desc[sizeof(long) - 1]; /* First few chars of description */ 105 u8 desc_len; 106 #endif 107 }; 108 unsigned long x; 109 }; 110 struct key_type *type; 111 struct key_tag *domain_tag; /* Domain of operation */ 112 const char *description; 113 }; 114 115 union key_payload { 116 void __rcu *rcu_data0; 117 void *data[4]; 118 }; 119 120 /*****************************************************************************/ 121 /* 122 * key reference with possession attribute handling 123 * 124 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually 125 * defined. This is because we abuse the bottom bit of the reference to carry a 126 * flag to indicate whether the calling process possesses that key in one of 127 * its keyrings. 128 * 129 * the key_ref_t has been made a separate type so that the compiler can reject 130 * attempts to dereference it without proper conversion. 131 * 132 * the three functions are used to assemble and disassemble references 133 */ 134 typedef struct __key_reference_with_attributes *key_ref_t; 135 136 static inline key_ref_t make_key_ref(const struct key *key, 137 bool possession) 138 { 139 return (key_ref_t) ((unsigned long) key | possession); 140 } 141 142 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref) 143 { 144 return (struct key *) ((unsigned long) key_ref & ~1UL); 145 } 146 147 static inline bool is_key_possessed(const key_ref_t key_ref) 148 { 149 return (unsigned long) key_ref & 1UL; 150 } 151 152 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring, 153 const struct key_type *type, 154 const union key_payload *payload, 155 struct key *restriction_key); 156 157 struct key_restriction { 158 key_restrict_link_func_t check; 159 struct key *key; 160 struct key_type *keytype; 161 }; 162 163 enum key_state { 164 KEY_IS_UNINSTANTIATED, 165 KEY_IS_POSITIVE, /* Positively instantiated */ 166 }; 167 168 /*****************************************************************************/ 169 /* 170 * authentication token / access credential / keyring 171 * - types of key include: 172 * - keyrings 173 * - disk encryption IDs 174 * - Kerberos TGTs and tickets 175 */ 176 struct key { 177 refcount_t usage; /* number of references */ 178 key_serial_t serial; /* key serial number */ 179 union { 180 struct list_head graveyard_link; 181 struct rb_node serial_node; 182 }; 183 struct rw_semaphore sem; /* change vs change sem */ 184 struct key_user *user; /* owner of this key */ 185 void *security; /* security data for this key */ 186 union { 187 time64_t expiry; /* time at which key expires (or 0) */ 188 time64_t revoked_at; /* time at which key was revoked */ 189 }; 190 time64_t last_used_at; /* last time used for LRU keyring discard */ 191 kuid_t uid; 192 kgid_t gid; 193 key_perm_t perm; /* access permissions */ 194 unsigned short quotalen; /* length added to quota */ 195 unsigned short datalen; /* payload data length 196 * - may not match RCU dereferenced payload 197 * - payload should contain own length 198 */ 199 short state; /* Key state (+) or rejection error (-) */ 200 201 #ifdef KEY_DEBUGGING 202 unsigned magic; 203 #define KEY_DEBUG_MAGIC 0x18273645u 204 #endif 205 206 unsigned long flags; /* status flags (change with bitops) */ 207 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */ 208 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */ 209 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */ 210 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */ 211 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */ 212 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */ 213 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */ 214 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */ 215 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */ 216 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */ 217 218 /* the key type and key description string 219 * - the desc is used to match a key against search criteria 220 * - it should be a printable string 221 * - eg: for krb5 AFS, this might be "[email protected]" 222 */ 223 union { 224 struct keyring_index_key index_key; 225 struct { 226 unsigned long hash; 227 unsigned long len_desc; 228 struct key_type *type; /* type of key */ 229 struct key_tag *domain_tag; /* Domain of operation */ 230 char *description; 231 }; 232 }; 233 234 /* key data 235 * - this is used to hold the data actually used in cryptography or 236 * whatever 237 */ 238 union { 239 union key_payload payload; 240 struct { 241 /* Keyring bits */ 242 struct list_head name_link; 243 struct assoc_array keys; 244 }; 245 }; 246 247 /* This is set on a keyring to restrict the addition of a link to a key 248 * to it. If this structure isn't provided then it is assumed that the 249 * keyring is open to any addition. It is ignored for non-keyring 250 * keys. Only set this value using keyring_restrict(), keyring_alloc(), 251 * or key_alloc(). 252 * 253 * This is intended for use with rings of trusted keys whereby addition 254 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION 255 * overrides this, allowing the kernel to add extra keys without 256 * restriction. 257 */ 258 struct key_restriction *restrict_link; 259 }; 260 261 extern struct key *key_alloc(struct key_type *type, 262 const char *desc, 263 kuid_t uid, kgid_t gid, 264 const struct cred *cred, 265 key_perm_t perm, 266 unsigned long flags, 267 struct key_restriction *restrict_link); 268 269 270 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ 271 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ 272 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ 273 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ 274 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ 275 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ 276 277 extern void key_revoke(struct key *key); 278 extern void key_invalidate(struct key *key); 279 extern void key_put(struct key *key); 280 extern bool key_put_tag(struct key_tag *tag); 281 282 static inline struct key *__key_get(struct key *key) 283 { 284 refcount_inc(&key->usage); 285 return key; 286 } 287 288 static inline struct key *key_get(struct key *key) 289 { 290 return key ? __key_get(key) : key; 291 } 292 293 static inline void key_ref_put(key_ref_t key_ref) 294 { 295 key_put(key_ref_to_ptr(key_ref)); 296 } 297 298 extern struct key *request_key(struct key_type *type, 299 const char *description, 300 const char *callout_info); 301 302 extern struct key *request_key_rcu(struct key_type *type, 303 const char *description); 304 305 extern struct key *request_key_with_auxdata(struct key_type *type, 306 const char *description, 307 const void *callout_info, 308 size_t callout_len, 309 void *aux); 310 311 extern int wait_for_key_construction(struct key *key, bool intr); 312 313 extern int key_validate(const struct key *key); 314 315 extern key_ref_t key_create_or_update(key_ref_t keyring, 316 const char *type, 317 const char *description, 318 const void *payload, 319 size_t plen, 320 key_perm_t perm, 321 unsigned long flags); 322 323 extern int key_update(key_ref_t key, 324 const void *payload, 325 size_t plen); 326 327 extern int key_link(struct key *keyring, 328 struct key *key); 329 330 extern int key_move(struct key *key, 331 struct key *from_keyring, 332 struct key *to_keyring, 333 unsigned int flags); 334 335 extern int key_unlink(struct key *keyring, 336 struct key *key); 337 338 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 339 const struct cred *cred, 340 key_perm_t perm, 341 unsigned long flags, 342 struct key_restriction *restrict_link, 343 struct key *dest); 344 345 extern int restrict_link_reject(struct key *keyring, 346 const struct key_type *type, 347 const union key_payload *payload, 348 struct key *restriction_key); 349 350 extern int keyring_clear(struct key *keyring); 351 352 extern key_ref_t keyring_search(key_ref_t keyring, 353 struct key_type *type, 354 const char *description, 355 bool recurse); 356 357 extern int keyring_add_key(struct key *keyring, 358 struct key *key); 359 360 extern int keyring_restrict(key_ref_t keyring, const char *type, 361 const char *restriction); 362 363 extern struct key *key_lookup(key_serial_t id); 364 365 static inline key_serial_t key_serial(const struct key *key) 366 { 367 return key ? key->serial : 0; 368 } 369 370 extern void key_set_timeout(struct key *, unsigned); 371 372 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags, 373 key_perm_t perm); 374 extern void key_free_user_ns(struct user_namespace *); 375 376 /* 377 * The permissions required on a key that we're looking up. 378 */ 379 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ 380 #define KEY_NEED_READ 0x02 /* Require permission to read content */ 381 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ 382 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */ 383 #define KEY_NEED_LINK 0x10 /* Require permission to link */ 384 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */ 385 #define KEY_NEED_ALL 0x3f /* All the above permissions */ 386 387 static inline short key_read_state(const struct key *key) 388 { 389 /* Barrier versus mark_key_instantiated(). */ 390 return smp_load_acquire(&key->state); 391 } 392 393 /** 394 * key_is_positive - Determine if a key has been positively instantiated 395 * @key: The key to check. 396 * 397 * Return true if the specified key has been positively instantiated, false 398 * otherwise. 399 */ 400 static inline bool key_is_positive(const struct key *key) 401 { 402 return key_read_state(key) == KEY_IS_POSITIVE; 403 } 404 405 static inline bool key_is_negative(const struct key *key) 406 { 407 return key_read_state(key) < 0; 408 } 409 410 #define dereference_key_rcu(KEY) \ 411 (rcu_dereference((KEY)->payload.rcu_data0)) 412 413 #define dereference_key_locked(KEY) \ 414 (rcu_dereference_protected((KEY)->payload.rcu_data0, \ 415 rwsem_is_locked(&((struct key *)(KEY))->sem))) 416 417 #define rcu_assign_keypointer(KEY, PAYLOAD) \ 418 do { \ 419 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ 420 } while (0) 421 422 #ifdef CONFIG_SYSCTL 423 extern struct ctl_table key_sysctls[]; 424 #endif 425 /* 426 * the userspace interface 427 */ 428 extern int install_thread_keyring_to_cred(struct cred *cred); 429 extern void key_fsuid_changed(struct cred *new_cred); 430 extern void key_fsgid_changed(struct cred *new_cred); 431 extern void key_init(void); 432 433 #else /* CONFIG_KEYS */ 434 435 #define key_validate(k) 0 436 #define key_serial(k) 0 437 #define key_get(k) ({ NULL; }) 438 #define key_revoke(k) do { } while(0) 439 #define key_invalidate(k) do { } while(0) 440 #define key_put(k) do { } while(0) 441 #define key_ref_put(k) do { } while(0) 442 #define make_key_ref(k, p) NULL 443 #define key_ref_to_ptr(k) NULL 444 #define is_key_possessed(k) 0 445 #define key_fsuid_changed(c) do { } while(0) 446 #define key_fsgid_changed(c) do { } while(0) 447 #define key_init() do { } while(0) 448 #define key_free_user_ns(ns) do { } while(0) 449 450 #endif /* CONFIG_KEYS */ 451 #endif /* __KERNEL__ */ 452 #endif /* _LINUX_KEY_H */ 453