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 /*****************************************************************************/ 142 /* 143 * authentication token / access credential / keyring 144 * - types of key include: 145 * - keyrings 146 * - disk encryption IDs 147 * - Kerberos TGTs and tickets 148 */ 149 struct key { 150 refcount_t usage; /* number of references */ 151 key_serial_t serial; /* key serial number */ 152 union { 153 struct list_head graveyard_link; 154 struct rb_node serial_node; 155 }; 156 struct rw_semaphore sem; /* change vs change sem */ 157 struct key_user *user; /* owner of this key */ 158 void *security; /* security data for this key */ 159 union { 160 time_t expiry; /* time at which key expires (or 0) */ 161 time_t revoked_at; /* time at which key was revoked */ 162 }; 163 time_t last_used_at; /* last time used for LRU keyring discard */ 164 kuid_t uid; 165 kgid_t gid; 166 key_perm_t perm; /* access permissions */ 167 unsigned short quotalen; /* length added to quota */ 168 unsigned short datalen; /* payload data length 169 * - may not match RCU dereferenced payload 170 * - payload should contain own length 171 */ 172 173 #ifdef KEY_DEBUGGING 174 unsigned magic; 175 #define KEY_DEBUG_MAGIC 0x18273645u 176 #endif 177 178 unsigned long flags; /* status flags (change with bitops) */ 179 #define KEY_FLAG_INSTANTIATED 0 /* set if key has been instantiated */ 180 #define KEY_FLAG_DEAD 1 /* set if key type has been deleted */ 181 #define KEY_FLAG_REVOKED 2 /* set if key had been revoked */ 182 #define KEY_FLAG_IN_QUOTA 3 /* set if key consumes quota */ 183 #define KEY_FLAG_USER_CONSTRUCT 4 /* set if key is being constructed in userspace */ 184 #define KEY_FLAG_NEGATIVE 5 /* set if key is negative */ 185 #define KEY_FLAG_ROOT_CAN_CLEAR 6 /* set if key can be cleared by root without permission */ 186 #define KEY_FLAG_INVALIDATED 7 /* set if key has been invalidated */ 187 #define KEY_FLAG_BUILTIN 8 /* set if key is built in to the kernel */ 188 #define KEY_FLAG_ROOT_CAN_INVAL 9 /* set if key can be invalidated by root without permission */ 189 #define KEY_FLAG_KEEP 10 /* set if key should not be removed */ 190 191 /* the key type and key description string 192 * - the desc is used to match a key against search criteria 193 * - it should be a printable string 194 * - eg: for krb5 AFS, this might be "[email protected]" 195 */ 196 union { 197 struct keyring_index_key index_key; 198 struct { 199 struct key_type *type; /* type of key */ 200 char *description; 201 }; 202 }; 203 204 /* key data 205 * - this is used to hold the data actually used in cryptography or 206 * whatever 207 */ 208 union { 209 union key_payload payload; 210 struct { 211 /* Keyring bits */ 212 struct list_head name_link; 213 struct assoc_array keys; 214 }; 215 int reject_error; 216 }; 217 218 /* This is set on a keyring to restrict the addition of a link to a key 219 * to it. If this structure isn't provided then it is assumed that the 220 * keyring is open to any addition. It is ignored for non-keyring 221 * keys. Only set this value using keyring_restrict(), keyring_alloc(), 222 * or key_alloc(). 223 * 224 * This is intended for use with rings of trusted keys whereby addition 225 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION 226 * overrides this, allowing the kernel to add extra keys without 227 * restriction. 228 */ 229 struct key_restriction *restrict_link; 230 }; 231 232 extern struct key *key_alloc(struct key_type *type, 233 const char *desc, 234 kuid_t uid, kgid_t gid, 235 const struct cred *cred, 236 key_perm_t perm, 237 unsigned long flags, 238 struct key_restriction *restrict_link); 239 240 241 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ 242 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ 243 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ 244 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ 245 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ 246 247 extern void key_revoke(struct key *key); 248 extern void key_invalidate(struct key *key); 249 extern void key_put(struct key *key); 250 251 static inline struct key *__key_get(struct key *key) 252 { 253 refcount_inc(&key->usage); 254 return key; 255 } 256 257 static inline struct key *key_get(struct key *key) 258 { 259 return key ? __key_get(key) : key; 260 } 261 262 static inline void key_ref_put(key_ref_t key_ref) 263 { 264 key_put(key_ref_to_ptr(key_ref)); 265 } 266 267 extern struct key *request_key(struct key_type *type, 268 const char *description, 269 const char *callout_info); 270 271 extern struct key *request_key_with_auxdata(struct key_type *type, 272 const char *description, 273 const void *callout_info, 274 size_t callout_len, 275 void *aux); 276 277 extern struct key *request_key_async(struct key_type *type, 278 const char *description, 279 const void *callout_info, 280 size_t callout_len); 281 282 extern struct key *request_key_async_with_auxdata(struct key_type *type, 283 const char *description, 284 const void *callout_info, 285 size_t callout_len, 286 void *aux); 287 288 extern int wait_for_key_construction(struct key *key, bool intr); 289 290 extern int key_validate(const struct key *key); 291 292 extern key_ref_t key_create_or_update(key_ref_t keyring, 293 const char *type, 294 const char *description, 295 const void *payload, 296 size_t plen, 297 key_perm_t perm, 298 unsigned long flags); 299 300 extern int key_update(key_ref_t key, 301 const void *payload, 302 size_t plen); 303 304 extern int key_link(struct key *keyring, 305 struct key *key); 306 307 extern int key_unlink(struct key *keyring, 308 struct key *key); 309 310 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 311 const struct cred *cred, 312 key_perm_t perm, 313 unsigned long flags, 314 struct key_restriction *restrict_link, 315 struct key *dest); 316 317 extern int restrict_link_reject(struct key *keyring, 318 const struct key_type *type, 319 const union key_payload *payload, 320 struct key *restriction_key); 321 322 extern int keyring_clear(struct key *keyring); 323 324 extern key_ref_t keyring_search(key_ref_t keyring, 325 struct key_type *type, 326 const char *description); 327 328 extern int keyring_add_key(struct key *keyring, 329 struct key *key); 330 331 extern int keyring_restrict(key_ref_t keyring, const char *type, 332 const char *restriction); 333 334 extern struct key *key_lookup(key_serial_t id); 335 336 static inline key_serial_t key_serial(const struct key *key) 337 { 338 return key ? key->serial : 0; 339 } 340 341 extern void key_set_timeout(struct key *, unsigned); 342 343 /* 344 * The permissions required on a key that we're looking up. 345 */ 346 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ 347 #define KEY_NEED_READ 0x02 /* Require permission to read content */ 348 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ 349 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */ 350 #define KEY_NEED_LINK 0x10 /* Require permission to link */ 351 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */ 352 #define KEY_NEED_ALL 0x3f /* All the above permissions */ 353 354 /** 355 * key_is_instantiated - Determine if a key has been positively instantiated 356 * @key: The key to check. 357 * 358 * Return true if the specified key has been positively instantiated, false 359 * otherwise. 360 */ 361 static inline bool key_is_instantiated(const struct key *key) 362 { 363 return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) && 364 !test_bit(KEY_FLAG_NEGATIVE, &key->flags); 365 } 366 367 #define dereference_key_rcu(KEY) \ 368 (rcu_dereference((KEY)->payload.rcu_data0)) 369 370 #define dereference_key_locked(KEY) \ 371 (rcu_dereference_protected((KEY)->payload.rcu_data0, \ 372 rwsem_is_locked(&((struct key *)(KEY))->sem))) 373 374 #define rcu_assign_keypointer(KEY, PAYLOAD) \ 375 do { \ 376 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ 377 } while (0) 378 379 #ifdef CONFIG_SYSCTL 380 extern struct ctl_table key_sysctls[]; 381 #endif 382 /* 383 * the userspace interface 384 */ 385 extern int install_thread_keyring_to_cred(struct cred *cred); 386 extern void key_fsuid_changed(struct task_struct *tsk); 387 extern void key_fsgid_changed(struct task_struct *tsk); 388 extern void key_init(void); 389 390 #else /* CONFIG_KEYS */ 391 392 #define key_validate(k) 0 393 #define key_serial(k) 0 394 #define key_get(k) ({ NULL; }) 395 #define key_revoke(k) do { } while(0) 396 #define key_invalidate(k) do { } while(0) 397 #define key_put(k) do { } while(0) 398 #define key_ref_put(k) do { } while(0) 399 #define make_key_ref(k, p) NULL 400 #define key_ref_to_ptr(k) NULL 401 #define is_key_possessed(k) 0 402 #define key_fsuid_changed(t) do { } while(0) 403 #define key_fsgid_changed(t) do { } while(0) 404 #define key_init() do { } while(0) 405 406 #endif /* CONFIG_KEYS */ 407 #endif /* __KERNEL__ */ 408 #endif /* _LINUX_KEY_H */ 409