1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* Authentication token and access key management 3 * 4 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 * 7 * See Documentation/security/keys/core.rst for information on keys/keyrings. 8 */ 9 10 #ifndef _LINUX_KEY_H 11 #define _LINUX_KEY_H 12 13 #include <linux/types.h> 14 #include <linux/list.h> 15 #include <linux/rbtree.h> 16 #include <linux/rcupdate.h> 17 #include <linux/sysctl.h> 18 #include <linux/rwsem.h> 19 #include <linux/atomic.h> 20 #include <linux/assoc_array.h> 21 #include <linux/refcount.h> 22 #include <linux/time64.h> 23 24 #ifdef __KERNEL__ 25 #include <linux/uidgid.h> 26 27 /* key handle serial number */ 28 typedef int32_t key_serial_t; 29 30 /* key handle permissions mask */ 31 typedef uint32_t key_perm_t; 32 33 struct key; 34 35 #ifdef CONFIG_KEYS 36 37 #undef KEY_DEBUGGING 38 39 #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */ 40 #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */ 41 #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */ 42 #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */ 43 #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */ 44 #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */ 45 #define KEY_POS_ALL 0x3f000000 46 47 #define KEY_USR_VIEW 0x00010000 /* user permissions... */ 48 #define KEY_USR_READ 0x00020000 49 #define KEY_USR_WRITE 0x00040000 50 #define KEY_USR_SEARCH 0x00080000 51 #define KEY_USR_LINK 0x00100000 52 #define KEY_USR_SETATTR 0x00200000 53 #define KEY_USR_ALL 0x003f0000 54 55 #define KEY_GRP_VIEW 0x00000100 /* group permissions... */ 56 #define KEY_GRP_READ 0x00000200 57 #define KEY_GRP_WRITE 0x00000400 58 #define KEY_GRP_SEARCH 0x00000800 59 #define KEY_GRP_LINK 0x00001000 60 #define KEY_GRP_SETATTR 0x00002000 61 #define KEY_GRP_ALL 0x00003f00 62 63 #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */ 64 #define KEY_OTH_READ 0x00000002 65 #define KEY_OTH_WRITE 0x00000004 66 #define KEY_OTH_SEARCH 0x00000008 67 #define KEY_OTH_LINK 0x00000010 68 #define KEY_OTH_SETATTR 0x00000020 69 #define KEY_OTH_ALL 0x0000003f 70 71 #define KEY_PERM_UNDEF 0xffffffff 72 73 struct seq_file; 74 struct user_struct; 75 struct signal_struct; 76 struct cred; 77 78 struct key_type; 79 struct key_owner; 80 struct keyring_list; 81 struct keyring_name; 82 83 struct keyring_index_key { 84 struct key_type *type; 85 const char *description; 86 size_t desc_len; 87 }; 88 89 union key_payload { 90 void __rcu *rcu_data0; 91 void *data[4]; 92 }; 93 94 /*****************************************************************************/ 95 /* 96 * key reference with possession attribute handling 97 * 98 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually 99 * defined. This is because we abuse the bottom bit of the reference to carry a 100 * flag to indicate whether the calling process possesses that key in one of 101 * its keyrings. 102 * 103 * the key_ref_t has been made a separate type so that the compiler can reject 104 * attempts to dereference it without proper conversion. 105 * 106 * the three functions are used to assemble and disassemble references 107 */ 108 typedef struct __key_reference_with_attributes *key_ref_t; 109 110 static inline key_ref_t make_key_ref(const struct key *key, 111 bool possession) 112 { 113 return (key_ref_t) ((unsigned long) key | possession); 114 } 115 116 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref) 117 { 118 return (struct key *) ((unsigned long) key_ref & ~1UL); 119 } 120 121 static inline bool is_key_possessed(const key_ref_t key_ref) 122 { 123 return (unsigned long) key_ref & 1UL; 124 } 125 126 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring, 127 const struct key_type *type, 128 const union key_payload *payload, 129 struct key *restriction_key); 130 131 struct key_restriction { 132 key_restrict_link_func_t check; 133 struct key *key; 134 struct key_type *keytype; 135 }; 136 137 enum key_state { 138 KEY_IS_UNINSTANTIATED, 139 KEY_IS_POSITIVE, /* Positively instantiated */ 140 }; 141 142 /*****************************************************************************/ 143 /* 144 * authentication token / access credential / keyring 145 * - types of key include: 146 * - keyrings 147 * - disk encryption IDs 148 * - Kerberos TGTs and tickets 149 */ 150 struct key { 151 refcount_t usage; /* number of references */ 152 key_serial_t serial; /* key serial number */ 153 union { 154 struct list_head graveyard_link; 155 struct rb_node serial_node; 156 }; 157 struct rw_semaphore sem; /* change vs change sem */ 158 struct key_user *user; /* owner of this key */ 159 void *security; /* security data for this key */ 160 union { 161 time64_t expiry; /* time at which key expires (or 0) */ 162 time64_t revoked_at; /* time at which key was revoked */ 163 }; 164 time64_t last_used_at; /* last time used for LRU keyring discard */ 165 kuid_t uid; 166 kgid_t gid; 167 key_perm_t perm; /* access permissions */ 168 unsigned short quotalen; /* length added to quota */ 169 unsigned short datalen; /* payload data length 170 * - may not match RCU dereferenced payload 171 * - payload should contain own length 172 */ 173 short state; /* Key state (+) or rejection error (-) */ 174 175 #ifdef KEY_DEBUGGING 176 unsigned magic; 177 #define KEY_DEBUG_MAGIC 0x18273645u 178 #endif 179 180 unsigned long flags; /* status flags (change with bitops) */ 181 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */ 182 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */ 183 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */ 184 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */ 185 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */ 186 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */ 187 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */ 188 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */ 189 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */ 190 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */ 191 192 /* the key type and key description string 193 * - the desc is used to match a key against search criteria 194 * - it should be a printable string 195 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM" 196 */ 197 union { 198 struct keyring_index_key index_key; 199 struct { 200 struct key_type *type; /* type of key */ 201 char *description; 202 }; 203 }; 204 205 /* key data 206 * - this is used to hold the data actually used in cryptography or 207 * whatever 208 */ 209 union { 210 union key_payload payload; 211 struct { 212 /* Keyring bits */ 213 struct list_head name_link; 214 struct assoc_array keys; 215 }; 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 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ 247 248 extern void key_revoke(struct key *key); 249 extern void key_invalidate(struct key *key); 250 extern void key_put(struct key *key); 251 252 static inline struct key *__key_get(struct key *key) 253 { 254 refcount_inc(&key->usage); 255 return key; 256 } 257 258 static inline struct key *key_get(struct key *key) 259 { 260 return key ? __key_get(key) : key; 261 } 262 263 static inline void key_ref_put(key_ref_t key_ref) 264 { 265 key_put(key_ref_to_ptr(key_ref)); 266 } 267 268 extern struct key *request_key(struct key_type *type, 269 const char *description, 270 const char *callout_info); 271 272 extern struct key *request_key_with_auxdata(struct key_type *type, 273 const char *description, 274 const void *callout_info, 275 size_t callout_len, 276 void *aux); 277 278 extern struct key *request_key_async(struct key_type *type, 279 const char *description, 280 const void *callout_info, 281 size_t callout_len); 282 283 extern struct key *request_key_async_with_auxdata(struct key_type *type, 284 const char *description, 285 const void *callout_info, 286 size_t callout_len, 287 void *aux); 288 289 extern int wait_for_key_construction(struct key *key, bool intr); 290 291 extern int key_validate(const struct key *key); 292 293 extern key_ref_t key_create_or_update(key_ref_t keyring, 294 const char *type, 295 const char *description, 296 const void *payload, 297 size_t plen, 298 key_perm_t perm, 299 unsigned long flags); 300 301 extern int key_update(key_ref_t key, 302 const void *payload, 303 size_t plen); 304 305 extern int key_link(struct key *keyring, 306 struct key *key); 307 308 extern int key_unlink(struct key *keyring, 309 struct key *key); 310 311 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 312 const struct cred *cred, 313 key_perm_t perm, 314 unsigned long flags, 315 struct key_restriction *restrict_link, 316 struct key *dest); 317 318 extern int restrict_link_reject(struct key *keyring, 319 const struct key_type *type, 320 const union key_payload *payload, 321 struct key *restriction_key); 322 323 extern int keyring_clear(struct key *keyring); 324 325 extern key_ref_t keyring_search(key_ref_t keyring, 326 struct key_type *type, 327 const char *description); 328 329 extern int keyring_add_key(struct key *keyring, 330 struct key *key); 331 332 extern int keyring_restrict(key_ref_t keyring, const char *type, 333 const char *restriction); 334 335 extern struct key *key_lookup(key_serial_t id); 336 337 static inline key_serial_t key_serial(const struct key *key) 338 { 339 return key ? key->serial : 0; 340 } 341 342 extern void key_set_timeout(struct key *, unsigned); 343 344 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags, 345 key_perm_t perm); 346 347 /* 348 * The permissions required on a key that we're looking up. 349 */ 350 #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ 351 #define KEY_NEED_READ 0x02 /* Require permission to read content */ 352 #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ 353 #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */ 354 #define KEY_NEED_LINK 0x10 /* Require permission to link */ 355 #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */ 356 #define KEY_NEED_ALL 0x3f /* All the above permissions */ 357 358 static inline short key_read_state(const struct key *key) 359 { 360 /* Barrier versus mark_key_instantiated(). */ 361 return smp_load_acquire(&key->state); 362 } 363 364 /** 365 * key_is_positive - Determine if a key has been positively instantiated 366 * @key: The key to check. 367 * 368 * Return true if the specified key has been positively instantiated, false 369 * otherwise. 370 */ 371 static inline bool key_is_positive(const struct key *key) 372 { 373 return key_read_state(key) == KEY_IS_POSITIVE; 374 } 375 376 static inline bool key_is_negative(const struct key *key) 377 { 378 return key_read_state(key) < 0; 379 } 380 381 #define dereference_key_rcu(KEY) \ 382 (rcu_dereference((KEY)->payload.rcu_data0)) 383 384 #define dereference_key_locked(KEY) \ 385 (rcu_dereference_protected((KEY)->payload.rcu_data0, \ 386 rwsem_is_locked(&((struct key *)(KEY))->sem))) 387 388 #define rcu_assign_keypointer(KEY, PAYLOAD) \ 389 do { \ 390 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ 391 } while (0) 392 393 #ifdef CONFIG_SYSCTL 394 extern struct ctl_table key_sysctls[]; 395 #endif 396 /* 397 * the userspace interface 398 */ 399 extern int install_thread_keyring_to_cred(struct cred *cred); 400 extern void key_fsuid_changed(struct task_struct *tsk); 401 extern void key_fsgid_changed(struct task_struct *tsk); 402 extern void key_init(void); 403 404 #else /* CONFIG_KEYS */ 405 406 #define key_validate(k) 0 407 #define key_serial(k) 0 408 #define key_get(k) ({ NULL; }) 409 #define key_revoke(k) do { } while(0) 410 #define key_invalidate(k) do { } while(0) 411 #define key_put(k) do { } while(0) 412 #define key_ref_put(k) do { } while(0) 413 #define make_key_ref(k, p) NULL 414 #define key_ref_to_ptr(k) NULL 415 #define is_key_possessed(k) 0 416 #define key_fsuid_changed(t) do { } while(0) 417 #define key_fsgid_changed(t) do { } while(0) 418 #define key_init() do { } while(0) 419 420 #endif /* CONFIG_KEYS */ 421 #endif /* __KERNEL__ */ 422 #endif /* _LINUX_KEY_H */ 423