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 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 "[email protected]" 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 */ 437