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 28 #ifdef __KERNEL__ 29 #include <linux/uidgid.h> 30 31 /* key handle serial number */ 32 typedef int32_t key_serial_t; 33 34 /* key handle permissions mask */ 35 typedef uint32_t key_perm_t; 36 37 struct key; 38 39 #ifdef CONFIG_KEYS 40 41 #undef KEY_DEBUGGING 42 43 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */ 44 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */ 45 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */ 46 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */ 47 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */ 48 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */ 49 #define KEY_POS_ALL 0x3f000000 50 51 #define KEY_USR_VIEW 0x00010000 /* user permissions... */ 52 #define KEY_USR_READ 0x00020000 53 #define KEY_USR_WRITE 0x00040000 54 #define KEY_USR_SEARCH 0x00080000 55 #define KEY_USR_LINK 0x00100000 56 #define KEY_USR_SETATTR 0x00200000 57 #define KEY_USR_ALL 0x003f0000 58 59 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */ 60 #define KEY_GRP_READ 0x00000200 61 #define KEY_GRP_WRITE 0x00000400 62 #define KEY_GRP_SEARCH 0x00000800 63 #define KEY_GRP_LINK 0x00001000 64 #define KEY_GRP_SETATTR 0x00002000 65 #define KEY_GRP_ALL 0x00003f00 66 67 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */ 68 #define KEY_OTH_READ 0x00000002 69 #define KEY_OTH_WRITE 0x00000004 70 #define KEY_OTH_SEARCH 0x00000008 71 #define KEY_OTH_LINK 0x00000010 72 #define KEY_OTH_SETATTR 0x00000020 73 #define KEY_OTH_ALL 0x0000003f 74 75 #define KEY_PERM_UNDEF 0xffffffff 76 77 struct seq_file; 78 struct user_struct; 79 struct signal_struct; 80 struct cred; 81 82 struct key_type; 83 struct key_owner; 84 struct keyring_list; 85 struct keyring_name; 86 87 struct keyring_index_key { 88 struct key_type *type; 89 const char *description; 90 size_t desc_len; 91 }; 92 93 union key_payload { 94 void __rcu *rcu_data0; 95 void *data[4]; 96 }; 97 98 /*****************************************************************************/ 99 /* 100 * key reference with possession attribute handling 101 * 102 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually 103 * defined. This is because we abuse the bottom bit of the reference to carry a 104 * flag to indicate whether the calling process possesses that key in one of 105 * its keyrings. 106 * 107 * the key_ref_t has been made a separate type so that the compiler can reject 108 * attempts to dereference it without proper conversion. 109 * 110 * the three functions are used to assemble and disassemble references 111 */ 112 typedef struct __key_reference_with_attributes *key_ref_t; 113 114 static inline key_ref_t make_key_ref(const struct key *key, 115 bool possession) 116 { 117 return (key_ref_t) ((unsigned long) key | possession); 118 } 119 120 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref) 121 { 122 return (struct key *) ((unsigned long) key_ref & ~1UL); 123 } 124 125 static inline bool is_key_possessed(const key_ref_t key_ref) 126 { 127 return (unsigned long) key_ref & 1UL; 128 } 129 130 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring, 131 const struct key_type *type, 132 const union key_payload *payload, 133 struct key *restriction_key); 134 135 struct key_restriction { 136 key_restrict_link_func_t check; 137 struct key *key; 138 struct key_type *keytype; 139 }; 140 141 enum key_state { 142 KEY_IS_UNINSTANTIATED, 143 KEY_IS_POSITIVE, /* Positively instantiated */ 144 }; 145 146 /*****************************************************************************/ 147 /* 148 * authentication token / access credential / keyring 149 * - types of key include: 150 * - keyrings 151 * - disk encryption IDs 152 * - Kerberos TGTs and tickets 153 */ 154 struct key { 155 refcount_t usage; /* number of references */ 156 key_serial_t serial; /* key serial number */ 157 union { 158 struct list_head graveyard_link; 159 struct rb_node serial_node; 160 }; 161 struct rw_semaphore sem; /* change vs change sem */ 162 struct key_user *user; /* owner of this key */ 163 void *security; /* security data for this key */ 164 union { 165 time_t expiry; /* time at which key expires (or 0) */ 166 time_t revoked_at; /* time at which key was revoked */ 167 }; 168 time_t last_used_at; /* last time used for LRU keyring discard */ 169 kuid_t uid; 170 kgid_t gid; 171 key_perm_t perm; /* access permissions */ 172 unsigned short quotalen; /* length added to quota */ 173 unsigned short datalen; /* payload data length 174 * - may not match RCU dereferenced payload 175 * - payload should contain own length 176 */ 177 short state; /* Key state (+) or rejection error (-) */ 178 179 #ifdef KEY_DEBUGGING 180 unsigned magic; 181 #define KEY_DEBUG_MAGIC 0x18273645u 182 #endif 183 184 unsigned long flags; /* status flags (change with bitops) */ 185 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */ 186 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */ 187 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */ 188 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */ 189 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */ 190 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */ 191 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */ 192 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */ 193 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */ 194 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */ 195 196 /* the key type and key description string 197 * - the desc is used to match a key against search criteria 198 * - it should be a printable string 199 * - eg: for krb5 AFS, this might be "[email protected]" 200 */ 201 union { 202 struct keyring_index_key index_key; 203 struct { 204 struct key_type *type; /* type of key */ 205 char *description; 206 }; 207 }; 208 209 /* key data 210 * - this is used to hold the data actually used in cryptography or 211 * whatever 212 */ 213 union { 214 union key_payload payload; 215 struct { 216 /* Keyring bits */ 217 struct list_head name_link; 218 struct assoc_array keys; 219 }; 220 }; 221 222 /* This is set on a keyring to restrict the addition of a link to a key 223 * to it. If this structure isn't provided then it is assumed that the 224 * keyring is open to any addition. It is ignored for non-keyring 225 * keys. Only set this value using keyring_restrict(), keyring_alloc(), 226 * or key_alloc(). 227 * 228 * This is intended for use with rings of trusted keys whereby addition 229 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION 230 * overrides this, allowing the kernel to add extra keys without 231 * restriction. 232 */ 233 struct key_restriction *restrict_link; 234 }; 235 236 extern struct key *key_alloc(struct key_type *type, 237 const char *desc, 238 kuid_t uid, kgid_t gid, 239 const struct cred *cred, 240 key_perm_t perm, 241 unsigned long flags, 242 struct key_restriction *restrict_link); 243 244 245 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ 246 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ 247 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ 248 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ 249 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ 250 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ 251 252 extern void key_revoke(struct key *key); 253 extern void key_invalidate(struct key *key); 254 extern void key_put(struct key *key); 255 256 static inline struct key *__key_get(struct key *key) 257 { 258 refcount_inc(&key->usage); 259 return key; 260 } 261 262 static inline struct key *key_get(struct key *key) 263 { 264 return key ? __key_get(key) : key; 265 } 266 267 static inline void key_ref_put(key_ref_t key_ref) 268 { 269 key_put(key_ref_to_ptr(key_ref)); 270 } 271 272 extern struct key *request_key(struct key_type *type, 273 const char *description, 274 const char *callout_info); 275 276 extern struct key *request_key_with_auxdata(struct key_type *type, 277 const char *description, 278 const void *callout_info, 279 size_t callout_len, 280 void *aux); 281 282 extern struct key *request_key_async(struct key_type *type, 283 const char *description, 284 const void *callout_info, 285 size_t callout_len); 286 287 extern struct key *request_key_async_with_auxdata(struct key_type *type, 288 const char *description, 289 const void *callout_info, 290 size_t callout_len, 291 void *aux); 292 293 extern int wait_for_key_construction(struct key *key, bool intr); 294 295 extern int key_validate(const struct key *key); 296 297 extern key_ref_t key_create_or_update(key_ref_t keyring, 298 const char *type, 299 const char *description, 300 const void *payload, 301 size_t plen, 302 key_perm_t perm, 303 unsigned long flags); 304 305 extern int key_update(key_ref_t key, 306 const void *payload, 307 size_t plen); 308 309 extern int key_link(struct key *keyring, 310 struct key *key); 311 312 extern int key_unlink(struct key *keyring, 313 struct key *key); 314 315 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 316 const struct cred *cred, 317 key_perm_t perm, 318 unsigned long flags, 319 struct key_restriction *restrict_link, 320 struct key *dest); 321 322 extern int restrict_link_reject(struct key *keyring, 323 const struct key_type *type, 324 const union key_payload *payload, 325 struct key *restriction_key); 326 327 extern int keyring_clear(struct key *keyring); 328 329 extern key_ref_t keyring_search(key_ref_t keyring, 330 struct key_type *type, 331 const char *description); 332 333 extern int keyring_add_key(struct key *keyring, 334 struct key *key); 335 336 extern int keyring_restrict(key_ref_t keyring, const char *type, 337 const char *restriction); 338 339 extern struct key *key_lookup(key_serial_t id); 340 341 static inline key_serial_t key_serial(const struct key *key) 342 { 343 return key ? key->serial : 0; 344 } 345 346 extern void key_set_timeout(struct key *, unsigned); 347 348 /* 349 * The permissions required on a key that we're looking up. 350 */ 351 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ 352 #define KEY_NEED_READ 0x02 /* Require permission to read content */ 353 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ 354 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */ 355 #define KEY_NEED_LINK 0x10 /* Require permission to link */ 356 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */ 357 #define KEY_NEED_ALL 0x3f /* All the above permissions */ 358 359 static inline short key_read_state(const struct key *key) 360 { 361 /* Barrier versus mark_key_instantiated(). */ 362 return smp_load_acquire(&key->state); 363 } 364 365 /** 366 * key_is_positive - Determine if a key has been positively instantiated 367 * @key: The key to check. 368 * 369 * Return true if the specified key has been positively instantiated, false 370 * otherwise. 371 */ 372 static inline bool key_is_positive(const struct key *key) 373 { 374 return key_read_state(key) == KEY_IS_POSITIVE; 375 } 376 377 static inline bool key_is_negative(const struct key *key) 378 { 379 return key_read_state(key) < 0; 380 } 381 382 #define dereference_key_rcu(KEY) \ 383 (rcu_dereference((KEY)->payload.rcu_data0)) 384 385 #define dereference_key_locked(KEY) \ 386 (rcu_dereference_protected((KEY)->payload.rcu_data0, \ 387 rwsem_is_locked(&((struct key *)(KEY))->sem))) 388 389 #define rcu_assign_keypointer(KEY, PAYLOAD) \ 390 do { \ 391 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ 392 } while (0) 393 394 #ifdef CONFIG_SYSCTL 395 extern struct ctl_table key_sysctls[]; 396 #endif 397 /* 398 * the userspace interface 399 */ 400 extern int install_thread_keyring_to_cred(struct cred *cred); 401 extern void key_fsuid_changed(struct task_struct *tsk); 402 extern void key_fsgid_changed(struct task_struct *tsk); 403 extern void key_init(void); 404 405 #else /* CONFIG_KEYS */ 406 407 #define key_validate(k) 0 408 #define key_serial(k) 0 409 #define key_get(k) ({ NULL; }) 410 #define key_revoke(k) do { } while(0) 411 #define key_invalidate(k) do { } while(0) 412 #define key_put(k) do { } while(0) 413 #define key_ref_put(k) do { } while(0) 414 #define make_key_ref(k, p) NULL 415 #define key_ref_to_ptr(k) NULL 416 #define is_key_possessed(k) 0 417 #define key_fsuid_changed(t) do { } while(0) 418 #define key_fsgid_changed(t) do { } while(0) 419 #define key_init() do { } while(0) 420 421 #endif /* CONFIG_KEYS */ 422 #endif /* __KERNEL__ */ 423 #endif /* _LINUX_KEY_H */ 424