1 /* Authentication token and access key management
3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 * See Documentation/security/keys/core.rst for information on keys/keyrings.
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>
30 #include <linux/uidgid.h>
32 /* key handle serial number */
33 typedef int32_t key_serial_t;
35 /* key handle permissions mask */
36 typedef uint32_t key_perm_t;
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
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
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
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
76 #define KEY_PERM_UNDEF 0xffffffff
88 struct keyring_index_key {
91 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
93 char desc[sizeof(long) - 1]; /* First few chars of description */
95 char desc[sizeof(long) - 1]; /* First few chars of description */
101 struct key_type *type;
102 const char *description;
106 void __rcu *rcu_data0;
110 /*****************************************************************************/
112 * key reference with possession attribute handling
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
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.
122 * the three functions are used to assemble and disassemble references
124 typedef struct __key_reference_with_attributes *key_ref_t;
126 static inline key_ref_t make_key_ref(const struct key *key,
129 return (key_ref_t) ((unsigned long) key | possession);
132 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
134 return (struct key *) ((unsigned long) key_ref & ~1UL);
137 static inline bool is_key_possessed(const key_ref_t key_ref)
139 return (unsigned long) key_ref & 1UL;
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);
147 struct key_restriction {
148 key_restrict_link_func_t check;
150 struct key_type *keytype;
154 KEY_IS_UNINSTANTIATED,
155 KEY_IS_POSITIVE, /* Positively instantiated */
158 /*****************************************************************************/
160 * authentication token / access credential / keyring
161 * - types of key include:
163 * - disk encryption IDs
164 * - Kerberos TGTs and tickets
167 refcount_t usage; /* number of references */
168 key_serial_t serial; /* key serial number */
170 struct list_head graveyard_link;
171 struct rb_node serial_node;
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 */
177 time64_t expiry; /* time at which key expires (or 0) */
178 time64_t revoked_at; /* time at which key was revoked */
180 time64_t last_used_at; /* last time used for LRU keyring discard */
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
189 short state; /* Key state (+) or rejection error (-) */
193 #define KEY_DEBUG_MAGIC 0x18273645u
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 */
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 "afs@REDHAT.COM"
214 struct keyring_index_key index_key;
216 unsigned long len_desc;
217 struct key_type *type; /* type of key */
223 * - this is used to hold the data actually used in cryptography or
227 union key_payload payload;
230 struct list_head name_link;
231 struct assoc_array keys;
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(),
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
246 struct key_restriction *restrict_link;
249 extern struct key *key_alloc(struct key_type *type,
251 kuid_t uid, kgid_t gid,
252 const struct cred *cred,
255 struct key_restriction *restrict_link);
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 */
265 extern void key_revoke(struct key *key);
266 extern void key_invalidate(struct key *key);
267 extern void key_put(struct key *key);
269 static inline struct key *__key_get(struct key *key)
271 refcount_inc(&key->usage);
275 static inline struct key *key_get(struct key *key)
277 return key ? __key_get(key) : key;
280 static inline void key_ref_put(key_ref_t key_ref)
282 key_put(key_ref_to_ptr(key_ref));
285 extern struct key *request_key(struct key_type *type,
286 const char *description,
287 const char *callout_info);
289 extern struct key *request_key_rcu(struct key_type *type,
290 const char *description);
292 extern struct key *request_key_with_auxdata(struct key_type *type,
293 const char *description,
294 const void *callout_info,
298 extern int wait_for_key_construction(struct key *key, bool intr);
300 extern int key_validate(const struct key *key);
302 extern key_ref_t key_create_or_update(key_ref_t keyring,
304 const char *description,
308 unsigned long flags);
310 extern int key_update(key_ref_t key,
314 extern int key_link(struct key *keyring,
317 extern int key_move(struct key *key,
318 struct key *from_keyring,
319 struct key *to_keyring,
322 extern int key_unlink(struct key *keyring,
325 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
326 const struct cred *cred,
329 struct key_restriction *restrict_link,
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);
337 extern int keyring_clear(struct key *keyring);
339 extern key_ref_t keyring_search(key_ref_t keyring,
340 struct key_type *type,
341 const char *description);
343 extern int keyring_add_key(struct key *keyring,
346 extern int keyring_restrict(key_ref_t keyring, const char *type,
347 const char *restriction);
349 extern struct key *key_lookup(key_serial_t id);
351 static inline key_serial_t key_serial(const struct key *key)
353 return key ? key->serial : 0;
356 extern void key_set_timeout(struct key *, unsigned);
358 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
362 * The permissions required on a key that we're looking up.
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 */
372 static inline short key_read_state(const struct key *key)
374 /* Barrier versus mark_key_instantiated(). */
375 return smp_load_acquire(&key->state);
379 * key_is_positive - Determine if a key has been positively instantiated
380 * @key: The key to check.
382 * Return true if the specified key has been positively instantiated, false
385 static inline bool key_is_positive(const struct key *key)
387 return key_read_state(key) == KEY_IS_POSITIVE;
390 static inline bool key_is_negative(const struct key *key)
392 return key_read_state(key) < 0;
395 #define dereference_key_rcu(KEY) \
396 (rcu_dereference((KEY)->payload.rcu_data0))
398 #define dereference_key_locked(KEY) \
399 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
400 rwsem_is_locked(&((struct key *)(KEY))->sem)))
402 #define rcu_assign_keypointer(KEY, PAYLOAD) \
404 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
408 extern struct ctl_table key_sysctls[];
411 * the userspace interface
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);
418 #else /* CONFIG_KEYS */
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)
434 #endif /* CONFIG_KEYS */
435 #endif /* __KERNEL__ */
436 #endif /* _LINUX_KEY_H */