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