1/* key.h: authentication token and access key management
2 *
3 * Copyright (C) 2004 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/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 <asm/atomic.h>
23
24#ifdef __KERNEL__
25
26/* key handle serial number */
27typedef int32_t key_serial_t;
28
29/* key handle permissions mask */
30typedef uint32_t key_perm_t;
31
32struct key;
33
34#ifdef CONFIG_KEYS
35
36#undef KEY_DEBUGGING
37
38#define KEY_POS_VIEW	0x01000000	/* possessor can view a key's attributes */
39#define KEY_POS_READ	0x02000000	/* possessor can read key payload / view keyring */
40#define KEY_POS_WRITE	0x04000000	/* possessor can update key payload / add link to keyring */
41#define KEY_POS_SEARCH	0x08000000	/* possessor can find a key in search / search a keyring */
42#define KEY_POS_LINK	0x10000000	/* possessor can create a link to a key/keyring */
43#define KEY_POS_SETATTR	0x20000000	/* possessor can set key attributes */
44#define KEY_POS_ALL	0x3f000000
45
46#define KEY_USR_VIEW	0x00010000	/* user permissions... */
47#define KEY_USR_READ	0x00020000
48#define KEY_USR_WRITE	0x00040000
49#define KEY_USR_SEARCH	0x00080000
50#define KEY_USR_LINK	0x00100000
51#define KEY_USR_SETATTR	0x00200000
52#define KEY_USR_ALL	0x003f0000
53
54#define KEY_GRP_VIEW	0x00000100	/* group permissions... */
55#define KEY_GRP_READ	0x00000200
56#define KEY_GRP_WRITE	0x00000400
57#define KEY_GRP_SEARCH	0x00000800
58#define KEY_GRP_LINK	0x00001000
59#define KEY_GRP_SETATTR	0x00002000
60#define KEY_GRP_ALL	0x00003f00
61
62#define KEY_OTH_VIEW	0x00000001	/* third party permissions... */
63#define KEY_OTH_READ	0x00000002
64#define KEY_OTH_WRITE	0x00000004
65#define KEY_OTH_SEARCH	0x00000008
66#define KEY_OTH_LINK	0x00000010
67#define KEY_OTH_SETATTR	0x00000020
68#define KEY_OTH_ALL	0x0000003f
69
70struct seq_file;
71struct user_struct;
72struct signal_struct;
73
74struct key_type;
75struct key_owner;
76struct keyring_list;
77struct keyring_name;
78
79/*****************************************************************************/
80/*
81 * key reference with possession attribute handling
82 *
83 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
84 * defined. This is because we abuse the bottom bit of the reference to carry a
85 * flag to indicate whether the calling process possesses that key in one of
86 * its keyrings.
87 *
88 * the key_ref_t has been made a separate type so that the compiler can reject
89 * attempts to dereference it without proper conversion.
90 *
91 * the three functions are used to assemble and disassemble references
92 */
93typedef struct __key_reference_with_attributes *key_ref_t;
94
95static inline key_ref_t make_key_ref(const struct key *key,
96				     unsigned long possession)
97{
98	return (key_ref_t) ((unsigned long) key | possession);
99}
100
101static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
102{
103	return (struct key *) ((unsigned long) key_ref & ~1UL);
104}
105
106static inline unsigned long is_key_possessed(const key_ref_t key_ref)
107{
108	return (unsigned long) key_ref & 1UL;
109}
110
111/*****************************************************************************/
112/*
113 * authentication token / access credential / keyring
114 * - types of key include:
115 *   - keyrings
116 *   - disk encryption IDs
117 *   - Kerberos TGTs and tickets
118 */
119struct key {
120	atomic_t		usage;		/* number of references */
121	key_serial_t		serial;		/* key serial number */
122	struct rb_node		serial_node;
123	struct key_type		*type;		/* type of key */
124	struct rw_semaphore	sem;		/* change vs change sem */
125	struct key_user		*user;		/* owner of this key */
126	void			*security;	/* security data for this key */
127	time_t			expiry;		/* time at which key expires (or 0) */
128	uid_t			uid;
129	gid_t			gid;
130	key_perm_t		perm;		/* access permissions */
131	unsigned short		quotalen;	/* length added to quota */
132	unsigned short		datalen;	/* payload data length
133						 * - may not match RCU dereferenced payload
134						 * - payload should contain own length
135						 */
136
137#ifdef KEY_DEBUGGING
138	unsigned		magic;
139#define KEY_DEBUG_MAGIC		0x18273645u
140#define KEY_DEBUG_MAGIC_X	0xf8e9dacbu
141#endif
142
143	unsigned long		flags;		/* status flags (change with bitops) */
144#define KEY_FLAG_INSTANTIATED	0	/* set if key has been instantiated */
145#define KEY_FLAG_DEAD		1	/* set if key type has been deleted */
146#define KEY_FLAG_REVOKED	2	/* set if key had been revoked */
147#define KEY_FLAG_IN_QUOTA	3	/* set if key consumes quota */
148#define KEY_FLAG_USER_CONSTRUCT	4	/* set if key is being constructed in userspace */
149#define KEY_FLAG_NEGATIVE	5	/* set if key is negative */
150
151	/* the description string
152	 * - this is used to match a key against search criteria
153	 * - this should be a printable string
154	 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
155	 */
156	char			*description;
157
158	/* type specific data
159	 * - this is used by the keyring type to index the name
160	 */
161	union {
162		struct list_head	link;
163		unsigned long		x[2];
164		void			*p[2];
165	} type_data;
166
167	/* key data
168	 * - this is used to hold the data actually used in cryptography or
169	 *   whatever
170	 */
171	union {
172		unsigned long		value;
173		void			*data;
174		struct keyring_list	*subscriptions;
175	} payload;
176};
177
178/*****************************************************************************/
179/*
180 * kernel managed key type definition
181 */
182typedef int (*request_key_actor_t)(struct key *key, struct key *authkey,
183				   const char *op, void *aux);
184
185struct key_type {
186	/* name of the type */
187	const char *name;
188
189	/* default payload length for quota precalculation (optional)
190	 * - this can be used instead of calling key_payload_reserve(), that
191	 *   function only needs to be called if the real datalen is different
192	 */
193	size_t def_datalen;
194
195	/* instantiate a key of this type
196	 * - this method should call key_payload_reserve() to determine if the
197	 *   user's quota will hold the payload
198	 */
199	int (*instantiate)(struct key *key, const void *data, size_t datalen);
200
201	/* update a key of this type (optional)
202	 * - this method should call key_payload_reserve() to recalculate the
203	 *   quota consumption
204	 * - the key must be locked against read when modifying
205	 */
206	int (*update)(struct key *key, const void *data, size_t datalen);
207
208	/* match a key against a description */
209	int (*match)(const struct key *key, const void *desc);
210
211	/* clear some of the data from a key on revokation (optional)
212	 * - the key's semaphore will be write-locked by the caller
213	 */
214	void (*revoke)(struct key *key);
215
216	/* clear the data from a key (optional) */
217	void (*destroy)(struct key *key);
218
219	/* describe a key */
220	void (*describe)(const struct key *key, struct seq_file *p);
221
222	/* read a key's data (optional)
223	 * - permission checks will be done by the caller
224	 * - the key's semaphore will be readlocked by the caller
225	 * - should return the amount of data that could be read, no matter how
226	 *   much is copied into the buffer
227	 * - shouldn't do the copy if the buffer is NULL
228	 */
229	long (*read)(const struct key *key, char __user *buffer, size_t buflen);
230
231	/* handle request_key() for this type instead of invoking
232	 * /sbin/request-key (optional)
233	 * - key is the key to instantiate
234	 * - authkey is the authority to assume when instantiating this key
235	 * - op is the operation to be done, usually "create"
236	 * - the call must not return until the instantiation process has run
237	 *   its course
238	 */
239	request_key_actor_t request_key;
240
241	/* internal fields */
242	struct list_head	link;		/* link in types list */
243};
244
245extern struct key_type key_type_keyring;
246
247extern int register_key_type(struct key_type *ktype);
248extern void unregister_key_type(struct key_type *ktype);
249
250extern struct key *key_alloc(struct key_type *type,
251			     const char *desc,
252			     uid_t uid, gid_t gid,
253			     struct task_struct *ctx,
254			     key_perm_t perm,
255			     unsigned long flags);
256
257
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
262extern int key_payload_reserve(struct key *key, size_t datalen);
263extern int key_instantiate_and_link(struct key *key,
264				    const void *data,
265				    size_t datalen,
266				    struct key *keyring,
267				    struct key *instkey);
268extern int key_negate_and_link(struct key *key,
269			       unsigned timeout,
270			       struct key *keyring,
271			       struct key *instkey);
272extern void key_revoke(struct key *key);
273extern void key_put(struct key *key);
274
275static inline struct key *key_get(struct key *key)
276{
277	if (key)
278		atomic_inc(&key->usage);
279	return key;
280}
281
282static inline void key_ref_put(key_ref_t key_ref)
283{
284	key_put(key_ref_to_ptr(key_ref));
285}
286
287extern struct key *request_key(struct key_type *type,
288			       const char *description,
289			       const char *callout_info);
290
291extern struct key *request_key_with_auxdata(struct key_type *type,
292					    const char *description,
293					    const char *callout_info,
294					    void *aux);
295
296extern int key_validate(struct key *key);
297
298extern key_ref_t key_create_or_update(key_ref_t keyring,
299				      const char *type,
300				      const char *description,
301				      const void *payload,
302				      size_t plen,
303				      unsigned long flags);
304
305extern int key_update(key_ref_t key,
306		      const void *payload,
307		      size_t plen);
308
309extern int key_link(struct key *keyring,
310		    struct key *key);
311
312extern int key_unlink(struct key *keyring,
313		      struct key *key);
314
315extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
316				 struct task_struct *ctx,
317				 unsigned long flags,
318				 struct key *dest);
319
320extern int keyring_clear(struct key *keyring);
321
322extern key_ref_t keyring_search(key_ref_t keyring,
323				struct key_type *type,
324				const char *description);
325
326extern int keyring_add_key(struct key *keyring,
327			   struct key *key);
328
329extern struct key *key_lookup(key_serial_t id);
330
331extern void keyring_replace_payload(struct key *key, void *replacement);
332
333#define key_serial(key) ((key) ? (key)->serial : 0)
334
335/*
336 * the userspace interface
337 */
338extern struct key root_user_keyring, root_session_keyring;
339extern int alloc_uid_keyring(struct user_struct *user,
340			     struct task_struct *ctx);
341extern void switch_uid_keyring(struct user_struct *new_user);
342extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
343extern int copy_thread_group_keys(struct task_struct *tsk);
344extern void exit_keys(struct task_struct *tsk);
345extern void exit_thread_group_keys(struct signal_struct *tg);
346extern int suid_keys(struct task_struct *tsk);
347extern int exec_keys(struct task_struct *tsk);
348extern void key_fsuid_changed(struct task_struct *tsk);
349extern void key_fsgid_changed(struct task_struct *tsk);
350extern void key_init(void);
351
352#define __install_session_keyring(tsk, keyring)			\
353({								\
354	struct key *old_session = tsk->signal->session_keyring;	\
355	tsk->signal->session_keyring = keyring;			\
356	old_session;						\
357})
358
359#else /* CONFIG_KEYS */
360
361#define key_validate(k)			0
362#define key_serial(k)			0
363#define key_get(k) 			({ NULL; })
364#define key_put(k)			do { } while(0)
365#define key_ref_put(k)			do { } while(0)
366#define make_key_ref(k)			({ NULL; })
367#define key_ref_to_ptr(k)		({ NULL; })
368#define is_key_possessed(k)		0
369#define alloc_uid_keyring(u,c)		0
370#define switch_uid_keyring(u)		do { } while(0)
371#define __install_session_keyring(t, k)	({ NULL; })
372#define copy_keys(f,t)			0
373#define copy_thread_group_keys(t)	0
374#define exit_keys(t)			do { } while(0)
375#define exit_thread_group_keys(tg)	do { } while(0)
376#define suid_keys(t)			do { } while(0)
377#define exec_keys(t)			do { } while(0)
378#define key_fsuid_changed(t)		do { } while(0)
379#define key_fsgid_changed(t)		do { } while(0)
380#define key_init()			do { } while(0)
381
382/* Initial keyrings */
383extern struct key root_user_keyring;
384extern struct key root_session_keyring;
385
386#endif /* CONFIG_KEYS */
387#endif /* __KERNEL__ */
388#endif /* _LINUX_KEY_H */
389