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