1/* Authentication token and access key management
2 *
3 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.txt 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
27#ifdef __KERNEL__
28#include <linux/uidgid.h>
29
30/* key handle serial number */
31typedef int32_t key_serial_t;
32
33/* key handle permissions mask */
34typedef uint32_t key_perm_t;
35
36struct key;
37
38#ifdef CONFIG_KEYS
39
40#undef KEY_DEBUGGING
41
42#define KEY_POS_VIEW	0x01000000	/* possessor can view a key's attributes */
43#define KEY_POS_READ	0x02000000	/* possessor can read key payload / view keyring */
44#define KEY_POS_WRITE	0x04000000	/* possessor can update key payload / add link to keyring */
45#define KEY_POS_SEARCH	0x08000000	/* possessor can find a key in search / search a keyring */
46#define KEY_POS_LINK	0x10000000	/* possessor can create a link to a key/keyring */
47#define KEY_POS_SETATTR	0x20000000	/* possessor can set key attributes */
48#define KEY_POS_ALL	0x3f000000
49
50#define KEY_USR_VIEW	0x00010000	/* user permissions... */
51#define KEY_USR_READ	0x00020000
52#define KEY_USR_WRITE	0x00040000
53#define KEY_USR_SEARCH	0x00080000
54#define KEY_USR_LINK	0x00100000
55#define KEY_USR_SETATTR	0x00200000
56#define KEY_USR_ALL	0x003f0000
57
58#define KEY_GRP_VIEW	0x00000100	/* group permissions... */
59#define KEY_GRP_READ	0x00000200
60#define KEY_GRP_WRITE	0x00000400
61#define KEY_GRP_SEARCH	0x00000800
62#define KEY_GRP_LINK	0x00001000
63#define KEY_GRP_SETATTR	0x00002000
64#define KEY_GRP_ALL	0x00003f00
65
66#define KEY_OTH_VIEW	0x00000001	/* third party permissions... */
67#define KEY_OTH_READ	0x00000002
68#define KEY_OTH_WRITE	0x00000004
69#define KEY_OTH_SEARCH	0x00000008
70#define KEY_OTH_LINK	0x00000010
71#define KEY_OTH_SETATTR	0x00000020
72#define KEY_OTH_ALL	0x0000003f
73
74#define KEY_PERM_UNDEF	0xffffffff
75
76struct seq_file;
77struct user_struct;
78struct signal_struct;
79struct cred;
80
81struct key_type;
82struct key_owner;
83struct keyring_list;
84struct keyring_name;
85
86struct keyring_index_key {
87	struct key_type		*type;
88	const char		*description;
89	size_t			desc_len;
90};
91
92/*****************************************************************************/
93/*
94 * key reference with possession attribute handling
95 *
96 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
97 * defined. This is because we abuse the bottom bit of the reference to carry a
98 * flag to indicate whether the calling process possesses that key in one of
99 * its keyrings.
100 *
101 * the key_ref_t has been made a separate type so that the compiler can reject
102 * attempts to dereference it without proper conversion.
103 *
104 * the three functions are used to assemble and disassemble references
105 */
106typedef struct __key_reference_with_attributes *key_ref_t;
107
108static inline key_ref_t make_key_ref(const struct key *key,
109				     bool possession)
110{
111	return (key_ref_t) ((unsigned long) key | possession);
112}
113
114static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
115{
116	return (struct key *) ((unsigned long) key_ref & ~1UL);
117}
118
119static inline bool is_key_possessed(const key_ref_t key_ref)
120{
121	return (unsigned long) key_ref & 1UL;
122}
123
124/*****************************************************************************/
125/*
126 * authentication token / access credential / keyring
127 * - types of key include:
128 *   - keyrings
129 *   - disk encryption IDs
130 *   - Kerberos TGTs and tickets
131 */
132struct key {
133	atomic_t		usage;		/* number of references */
134	key_serial_t		serial;		/* key serial number */
135	union {
136		struct list_head graveyard_link;
137		struct rb_node	serial_node;
138	};
139	struct rw_semaphore	sem;		/* change vs change sem */
140	struct key_user		*user;		/* owner of this key */
141	void			*security;	/* security data for this key */
142	union {
143		time_t		expiry;		/* time at which key expires (or 0) */
144		time_t		revoked_at;	/* time at which key was revoked */
145	};
146	time_t			last_used_at;	/* last time used for LRU keyring discard */
147	kuid_t			uid;
148	kgid_t			gid;
149	key_perm_t		perm;		/* access permissions */
150	unsigned short		quotalen;	/* length added to quota */
151	unsigned short		datalen;	/* payload data length
152						 * - may not match RCU dereferenced payload
153						 * - payload should contain own length
154						 */
155
156#ifdef KEY_DEBUGGING
157	unsigned		magic;
158#define KEY_DEBUG_MAGIC		0x18273645u
159#define KEY_DEBUG_MAGIC_X	0xf8e9dacbu
160#endif
161
162	unsigned long		flags;		/* status flags (change with bitops) */
163#define KEY_FLAG_INSTANTIATED	0	/* set if key has been instantiated */
164#define KEY_FLAG_DEAD		1	/* set if key type has been deleted */
165#define KEY_FLAG_REVOKED	2	/* set if key had been revoked */
166#define KEY_FLAG_IN_QUOTA	3	/* set if key consumes quota */
167#define KEY_FLAG_USER_CONSTRUCT	4	/* set if key is being constructed in userspace */
168#define KEY_FLAG_NEGATIVE	5	/* set if key is negative */
169#define KEY_FLAG_ROOT_CAN_CLEAR	6	/* set if key can be cleared by root without permission */
170#define KEY_FLAG_INVALIDATED	7	/* set if key has been invalidated */
171#define KEY_FLAG_TRUSTED	8	/* set if key is trusted */
172#define KEY_FLAG_TRUSTED_ONLY	9	/* set if keyring only accepts links to trusted keys */
173#define KEY_FLAG_BUILTIN	10	/* set if key is builtin */
174#define KEY_FLAG_ROOT_CAN_INVAL	11	/* set if key can be invalidated by root without permission */
175
176	/* the key type and key description string
177	 * - the desc is used to match a key against search criteria
178	 * - it should be a printable string
179	 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
180	 */
181	union {
182		struct keyring_index_key index_key;
183		struct {
184			struct key_type	*type;		/* type of key */
185			char		*description;
186		};
187	};
188
189	/* type specific data
190	 * - this is used by the keyring type to index the name
191	 */
192	union {
193		struct list_head	link;
194		unsigned long		x[2];
195		void			*p[2];
196		int			reject_error;
197	} type_data;
198
199	/* key data
200	 * - this is used to hold the data actually used in cryptography or
201	 *   whatever
202	 */
203	union {
204		union {
205			unsigned long		value;
206			void __rcu		*rcudata;
207			void			*data;
208			void			*data2[2];
209		} payload;
210		struct assoc_array keys;
211	};
212};
213
214extern struct key *key_alloc(struct key_type *type,
215			     const char *desc,
216			     kuid_t uid, kgid_t gid,
217			     const struct cred *cred,
218			     key_perm_t perm,
219			     unsigned long flags);
220
221
222#define KEY_ALLOC_IN_QUOTA	0x0000	/* add to quota, reject if would overrun */
223#define KEY_ALLOC_QUOTA_OVERRUN	0x0001	/* add to quota, permit even if overrun */
224#define KEY_ALLOC_NOT_IN_QUOTA	0x0002	/* not in quota */
225#define KEY_ALLOC_TRUSTED	0x0004	/* Key should be flagged as trusted */
226
227extern void key_revoke(struct key *key);
228extern void key_invalidate(struct key *key);
229extern void key_put(struct key *key);
230
231static inline struct key *__key_get(struct key *key)
232{
233	atomic_inc(&key->usage);
234	return key;
235}
236
237static inline struct key *key_get(struct key *key)
238{
239	return key ? __key_get(key) : key;
240}
241
242static inline void key_ref_put(key_ref_t key_ref)
243{
244	key_put(key_ref_to_ptr(key_ref));
245}
246
247extern struct key *request_key(struct key_type *type,
248			       const char *description,
249			       const char *callout_info);
250
251extern struct key *request_key_with_auxdata(struct key_type *type,
252					    const char *description,
253					    const void *callout_info,
254					    size_t callout_len,
255					    void *aux);
256
257extern struct key *request_key_async(struct key_type *type,
258				     const char *description,
259				     const void *callout_info,
260				     size_t callout_len);
261
262extern struct key *request_key_async_with_auxdata(struct key_type *type,
263						  const char *description,
264						  const void *callout_info,
265						  size_t callout_len,
266						  void *aux);
267
268extern int wait_for_key_construction(struct key *key, bool intr);
269
270extern int key_validate(const struct key *key);
271
272extern key_ref_t key_create_or_update(key_ref_t keyring,
273				      const char *type,
274				      const char *description,
275				      const void *payload,
276				      size_t plen,
277				      key_perm_t perm,
278				      unsigned long flags);
279
280extern int key_update(key_ref_t key,
281		      const void *payload,
282		      size_t plen);
283
284extern int key_link(struct key *keyring,
285		    struct key *key);
286
287extern int key_unlink(struct key *keyring,
288		      struct key *key);
289
290extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
291				 const struct cred *cred,
292				 key_perm_t perm,
293				 unsigned long flags,
294				 struct key *dest);
295
296extern int keyring_clear(struct key *keyring);
297
298extern key_ref_t keyring_search(key_ref_t keyring,
299				struct key_type *type,
300				const char *description);
301
302extern int keyring_add_key(struct key *keyring,
303			   struct key *key);
304
305extern struct key *key_lookup(key_serial_t id);
306
307static inline key_serial_t key_serial(const struct key *key)
308{
309	return key ? key->serial : 0;
310}
311
312extern void key_set_timeout(struct key *, unsigned);
313
314/*
315 * The permissions required on a key that we're looking up.
316 */
317#define	KEY_NEED_VIEW	0x01	/* Require permission to view attributes */
318#define	KEY_NEED_READ	0x02	/* Require permission to read content */
319#define	KEY_NEED_WRITE	0x04	/* Require permission to update / modify */
320#define	KEY_NEED_SEARCH	0x08	/* Require permission to search (keyring) or find (key) */
321#define	KEY_NEED_LINK	0x10	/* Require permission to link */
322#define	KEY_NEED_SETATTR 0x20	/* Require permission to change attributes */
323#define	KEY_NEED_ALL	0x3f	/* All the above permissions */
324
325/**
326 * key_is_instantiated - Determine if a key has been positively instantiated
327 * @key: The key to check.
328 *
329 * Return true if the specified key has been positively instantiated, false
330 * otherwise.
331 */
332static inline bool key_is_instantiated(const struct key *key)
333{
334	return test_bit(KEY_FLAG_INSTANTIATED, &key->flags) &&
335		!test_bit(KEY_FLAG_NEGATIVE, &key->flags);
336}
337
338#define rcu_dereference_key(KEY)					\
339	(rcu_dereference_protected((KEY)->payload.rcudata,		\
340				   rwsem_is_locked(&((struct key *)(KEY))->sem)))
341
342#define rcu_assign_keypointer(KEY, PAYLOAD)				\
343do {									\
344	rcu_assign_pointer((KEY)->payload.rcudata, (PAYLOAD));		\
345} while (0)
346
347#ifdef CONFIG_SYSCTL
348extern struct ctl_table key_sysctls[];
349#endif
350/*
351 * the userspace interface
352 */
353extern int install_thread_keyring_to_cred(struct cred *cred);
354extern void key_fsuid_changed(struct task_struct *tsk);
355extern void key_fsgid_changed(struct task_struct *tsk);
356extern void key_init(void);
357
358#else /* CONFIG_KEYS */
359
360#define key_validate(k)			0
361#define key_serial(k)			0
362#define key_get(k) 			({ NULL; })
363#define key_revoke(k)			do { } while(0)
364#define key_invalidate(k)		do { } while(0)
365#define key_put(k)			do { } while(0)
366#define key_ref_put(k)			do { } while(0)
367#define make_key_ref(k, p)		NULL
368#define key_ref_to_ptr(k)		NULL
369#define is_key_possessed(k)		0
370#define key_fsuid_changed(t)		do { } while(0)
371#define key_fsgid_changed(t)		do { } while(0)
372#define key_init()			do { } while(0)
373
374#endif /* CONFIG_KEYS */
375#endif /* __KERNEL__ */
376#endif /* _LINUX_KEY_H */
377