1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Authentication token and access key management
4 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
7 * See Documentation/security/keys/core.rst for information on keys/keyrings.
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>
25 #include <linux/uidgid.h>
27 /* key handle serial number */
28 typedef int32_t key_serial_t;
35 #include <linux/keyctl.h>
53 bool removed; /* T when subject removed */
56 struct keyring_index_key {
57 /* [!] If this structure is altered, the union in struct key must change too! */
58 unsigned long hash; /* Hash value */
61 #ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
63 char desc[sizeof(long) - 1]; /* First few chars of description */
65 char desc[sizeof(long) - 1]; /* First few chars of description */
71 struct key_type *type;
72 struct key_tag *domain_tag; /* Domain of operation */
73 const char *description;
77 void __rcu *rcu_data0;
87 unsigned int subject_id;
93 unsigned short nr_ace;
94 bool possessor_viewable;
96 struct key_ace aces[];
99 #define KEY_POSSESSOR_ACE(perms) { \
100 .type = KEY_ACE_SUBJ_STANDARD, \
102 .subject_id = KEY_ACE_POSSESSOR \
105 #define KEY_OWNER_ACE(perms) { \
106 .type = KEY_ACE_SUBJ_STANDARD, \
108 .subject_id = KEY_ACE_OWNER \
111 /*****************************************************************************/
113 * key reference with possession attribute handling
115 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
116 * defined. This is because we abuse the bottom bit of the reference to carry a
117 * flag to indicate whether the calling process possesses that key in one of
120 * the key_ref_t has been made a separate type so that the compiler can reject
121 * attempts to dereference it without proper conversion.
123 * the three functions are used to assemble and disassemble references
125 typedef struct __key_reference_with_attributes *key_ref_t;
127 static inline key_ref_t make_key_ref(const struct key *key,
130 return (key_ref_t) ((unsigned long) key | possession);
133 static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
135 return (struct key *) ((unsigned long) key_ref & ~1UL);
138 static inline bool is_key_possessed(const key_ref_t key_ref)
140 return (unsigned long) key_ref & 1UL;
143 typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
144 const struct key_type *type,
145 const union key_payload *payload,
146 struct key *restriction_key);
148 struct key_restriction {
149 key_restrict_link_func_t check;
151 struct key_type *keytype;
155 KEY_IS_UNINSTANTIATED,
156 KEY_IS_POSITIVE, /* Positively instantiated */
159 /*****************************************************************************/
161 * authentication token / access credential / keyring
162 * - types of key include:
164 * - disk encryption IDs
165 * - Kerberos TGTs and tickets
168 refcount_t usage; /* number of references */
169 key_serial_t serial; /* key serial number */
171 struct list_head graveyard_link;
172 struct rb_node serial_node;
174 struct rw_semaphore sem; /* change vs change sem */
175 struct key_user *user; /* owner of this key */
176 void *security; /* security data for this key */
177 struct key_acl __rcu *acl;
179 time64_t expiry; /* time at which key expires (or 0) */
180 time64_t revoked_at; /* time at which key was revoked */
182 time64_t last_used_at; /* last time used for LRU keyring discard */
185 unsigned short quotalen; /* length added to quota */
186 unsigned short datalen; /* payload data length
187 * - may not match RCU dereferenced payload
188 * - payload should contain own length
190 short state; /* Key state (+) or rejection error (-) */
194 #define KEY_DEBUG_MAGIC 0x18273645u
197 unsigned long flags; /* status flags (change with bitops) */
198 #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */
199 #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */
200 #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */
201 #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */
202 #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */
203 #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */
204 #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */
205 #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
206 #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
207 #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
208 #define KEY_FLAG_HAS_ACL 10 /* Set if KEYCTL_SETACL called on key */
210 /* the key type and key description string
211 * - the desc is used to match a key against search criteria
212 * - it should be a printable string
213 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
216 struct keyring_index_key index_key;
219 unsigned long len_desc;
220 struct key_type *type; /* type of key */
221 struct key_tag *domain_tag; /* Domain of operation */
227 * - this is used to hold the data actually used in cryptography or
231 union key_payload payload;
234 struct list_head name_link;
235 struct assoc_array keys;
239 /* This is set on a keyring to restrict the addition of a link to a key
240 * to it. If this structure isn't provided then it is assumed that the
241 * keyring is open to any addition. It is ignored for non-keyring
242 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
245 * This is intended for use with rings of trusted keys whereby addition
246 * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION
247 * overrides this, allowing the kernel to add extra keys without
250 struct key_restriction *restrict_link;
253 extern struct key *key_alloc(struct key_type *type,
255 kuid_t uid, kgid_t gid,
256 const struct cred *cred,
259 struct key_restriction *restrict_link);
262 #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */
263 #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */
264 #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */
265 #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */
266 #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
267 #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
269 extern void key_revoke(struct key *key);
270 extern void key_invalidate(struct key *key);
271 extern void key_put(struct key *key);
272 extern bool key_put_tag(struct key_tag *tag);
273 extern void key_remove_domain(struct key_tag *domain_tag);
275 static inline struct key *__key_get(struct key *key)
277 refcount_inc(&key->usage);
281 static inline struct key *key_get(struct key *key)
283 return key ? __key_get(key) : key;
286 static inline void key_ref_put(key_ref_t key_ref)
288 key_put(key_ref_to_ptr(key_ref));
291 extern struct key *request_key_tag(struct key_type *type,
292 const char *description,
293 struct key_tag *domain_tag,
294 const char *callout_info,
295 struct key_acl *acl);
297 extern struct key *request_key_rcu(struct key_type *type,
298 const char *description,
299 struct key_tag *domain_tag);
301 extern struct key *request_key_with_auxdata(struct key_type *type,
302 const char *description,
303 struct key_tag *domain_tag,
304 const void *callout_info,
307 struct key_acl *acl);
310 * request_key - Request a key and wait for construction
311 * @type: Type of key.
312 * @description: The searchable description of the key.
313 * @callout_info: The data to pass to the instantiation upcall (or NULL).
314 * @acl: The ACL to attach to a new key (or NULL).
316 * As for request_key_tag(), but with the default global domain tag.
318 static inline struct key *request_key(struct key_type *type,
319 const char *description,
320 const char *callout_info,
323 return request_key_tag(type, description, NULL, callout_info, acl);
328 * request_key_net - Request a key for a net namespace and wait for construction
329 * @type: Type of key.
330 * @description: The searchable description of the key.
331 * @net: The network namespace that is the key's domain of operation.
332 * @callout_info: The data to pass to the instantiation upcall (or NULL).
333 * @acl: The ACL to attach to a new key (or NULL).
335 * As for request_key() except that it does not add the returned key to a
336 * keyring if found, new keys are always allocated in the user's quota, the
337 * callout_info must be a NUL-terminated string and no auxiliary data can be
338 * passed. Only keys that operate the specified network namespace are used.
340 * Furthermore, it then works as wait_for_key_construction() to wait for the
341 * completion of keys undergoing construction with a non-interruptible wait.
343 #define request_key_net(type, description, net, callout_info, acl) \
344 request_key_tag(type, description, net->key_domain, callout_info, acl);
345 #endif /* CONFIG_NET */
347 extern int wait_for_key_construction(struct key *key, bool intr);
349 extern int key_validate(const struct key *key);
351 extern key_ref_t key_create_or_update(key_ref_t keyring,
353 const char *description,
357 unsigned long flags);
359 extern int key_update(key_ref_t key,
363 extern int key_link(struct key *keyring,
366 extern int key_move(struct key *key,
367 struct key *from_keyring,
368 struct key *to_keyring,
371 extern int key_unlink(struct key *keyring,
374 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
375 const struct cred *cred,
378 struct key_restriction *restrict_link,
381 extern int restrict_link_reject(struct key *keyring,
382 const struct key_type *type,
383 const union key_payload *payload,
384 struct key *restriction_key);
386 extern int keyring_clear(struct key *keyring);
388 extern key_ref_t keyring_search(key_ref_t keyring,
389 struct key_type *type,
390 const char *description,
393 extern int keyring_add_key(struct key *keyring,
396 extern int keyring_restrict(key_ref_t keyring, const char *type,
397 const char *restriction);
399 extern struct key *key_lookup(key_serial_t id);
401 static inline key_serial_t key_serial(const struct key *key)
403 return key ? key->serial : 0;
406 extern void key_set_timeout(struct key *, unsigned);
408 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
410 extern void key_free_user_ns(struct user_namespace *);
413 * The permissions required on a key that we're looking up.
415 #define KEY_NEED_VIEW 0x001 /* Require permission to view attributes */
416 #define KEY_NEED_READ 0x002 /* Require permission to read content */
417 #define KEY_NEED_WRITE 0x004 /* Require permission to update / modify */
418 #define KEY_NEED_SEARCH 0x008 /* Require permission to search (keyring) or find (key) */
419 #define KEY_NEED_LINK 0x010 /* Require permission to link */
420 #define KEY_NEED_SETSEC 0x020 /* Require permission to set owner, group, ACL */
421 #define KEY_NEED_INVAL 0x040 /* Require permission to invalidate key */
422 #define KEY_NEED_REVOKE 0x080 /* Require permission to revoke key */
423 #define KEY_NEED_JOIN 0x100 /* Require permission to join keyring as session */
424 #define KEY_NEED_CLEAR 0x200 /* Require permission to clear a keyring */
425 #define KEY_NEED_ALL 0x3ff
427 #define OLD_KEY_NEED_SETATTR 0x20 /* Used to be Require permission to change attributes */
429 extern struct key_acl internal_key_acl;
430 extern struct key_acl internal_keyring_acl;
431 extern struct key_acl internal_writable_keyring_acl;
433 static inline short key_read_state(const struct key *key)
435 /* Barrier versus mark_key_instantiated(). */
436 return smp_load_acquire(&key->state);
440 * key_is_positive - Determine if a key has been positively instantiated
441 * @key: The key to check.
443 * Return true if the specified key has been positively instantiated, false
446 static inline bool key_is_positive(const struct key *key)
448 return key_read_state(key) == KEY_IS_POSITIVE;
451 static inline bool key_is_negative(const struct key *key)
453 return key_read_state(key) < 0;
456 #define dereference_key_rcu(KEY) \
457 (rcu_dereference((KEY)->payload.rcu_data0))
459 #define dereference_key_locked(KEY) \
460 (rcu_dereference_protected((KEY)->payload.rcu_data0, \
461 rwsem_is_locked(&((struct key *)(KEY))->sem)))
463 #define rcu_assign_keypointer(KEY, PAYLOAD) \
465 rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \
469 extern struct ctl_table key_sysctls[];
472 * the userspace interface
474 extern int install_thread_keyring_to_cred(struct cred *cred);
475 extern void key_fsuid_changed(struct cred *new_cred);
476 extern void key_fsgid_changed(struct cred *new_cred);
477 extern void key_init(void);
479 #else /* CONFIG_KEYS */
481 #define key_validate(k) 0
482 #define key_serial(k) 0
483 #define key_get(k) ({ NULL; })
484 #define key_revoke(k) do { } while(0)
485 #define key_invalidate(k) do { } while(0)
486 #define key_put(k) do { } while(0)
487 #define key_ref_put(k) do { } while(0)
488 #define make_key_ref(k, p) NULL
489 #define key_ref_to_ptr(k) NULL
490 #define is_key_possessed(k) 0
491 #define key_fsuid_changed(c) do { } while(0)
492 #define key_fsgid_changed(c) do { } while(0)
493 #define key_init() do { } while(0)
494 #define key_free_user_ns(ns) do { } while(0)
495 #define key_remove_domain(d) do { } while(0)
497 #endif /* CONFIG_KEYS */
498 #endif /* __KERNEL__ */
499 #endif /* _LINUX_KEY_H */