aboutsummaryrefslogtreecommitdiff
path: root/include/linux/key.h
blob: 0f2e24f13c2bdff3c4136b5f2f914e394b1bcb15 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Authentication token and access key management
 *
 * Copyright (C) 2004, 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * See Documentation/security/keys/core.rst for information on keys/keyrings.
 */

#ifndef _LINUX_KEY_H
#define _LINUX_KEY_H

#include <linux/types.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/rcupdate.h>
#include <linux/sysctl.h>
#include <linux/rwsem.h>
#include <linux/atomic.h>
#include <linux/assoc_array.h>
#include <linux/refcount.h>
#include <linux/time64.h>

#ifdef __KERNEL__
#include <linux/uidgid.h>

/* key handle serial number */
typedef int32_t key_serial_t;

/* key handle permissions mask */
typedef uint32_t key_perm_t;

struct key;
struct net;

#ifdef CONFIG_KEYS

#undef KEY_DEBUGGING

#define KEY_POS_VIEW	0x01000000	/* possessor can view a key's attributes */
#define KEY_POS_READ	0x02000000	/* possessor can read key payload / view keyring */
#define KEY_POS_WRITE	0x04000000	/* possessor can update key payload / add link to keyring */
#define KEY_POS_SEARCH	0x08000000	/* possessor can find a key in search / search a keyring */
#define KEY_POS_LINK	0x10000000	/* possessor can create a link to a key/keyring */
#define KEY_POS_SETATTR	0x20000000	/* possessor can set key attributes */
#define KEY_POS_ALL	0x3f000000

#define KEY_USR_VIEW	0x00010000	/* user permissions... */
#define KEY_USR_READ	0x00020000
#define KEY_USR_WRITE	0x00040000
#define KEY_USR_SEARCH	0x00080000
#define KEY_USR_LINK	0x00100000
#define KEY_USR_SETATTR	0x00200000
#define KEY_USR_ALL	0x003f0000

#define KEY_GRP_VIEW	0x00000100	/* group permissions... */
#define KEY_GRP_READ	0x00000200
#define KEY_GRP_WRITE	0x00000400
#define KEY_GRP_SEARCH	0x00000800
#define KEY_GRP_LINK	0x00001000
#define KEY_GRP_SETATTR	0x00002000
#define KEY_GRP_ALL	0x00003f00

#define KEY_OTH_VIEW	0x00000001	/* third party permissions... */
#define KEY_OTH_READ	0x00000002
#define KEY_OTH_WRITE	0x00000004
#define KEY_OTH_SEARCH	0x00000008
#define KEY_OTH_LINK	0x00000010
#define KEY_OTH_SETATTR	0x00000020
#define KEY_OTH_ALL	0x0000003f

#define KEY_PERM_UNDEF	0xffffffff

/*
 * The permissions required on a key that we're looking up.
 */
enum key_need_perm {
	KEY_NEED_UNSPECIFIED,	/* Needed permission unspecified */
	KEY_NEED_VIEW,		/* Require permission to view attributes */
	KEY_NEED_READ,		/* Require permission to read content */
	KEY_NEED_WRITE,		/* Require permission to update / modify */
	KEY_NEED_SEARCH,	/* Require permission to search (keyring) or find (key) */
	KEY_NEED_LINK,		/* Require permission to link */
	KEY_NEED_SETATTR,	/* Require permission to change attributes */
	KEY_NEED_UNLINK,	/* Require permission to unlink key */
	KEY_SYSADMIN_OVERRIDE,	/* Special: override by CAP_SYS_ADMIN */
	KEY_AUTHTOKEN_OVERRIDE,	/* Special: override by possession of auth token */
	KEY_DEFER_PERM_CHECK,	/* Special: permission check is deferred */
};

struct seq_file;
struct user_struct;
struct signal_struct;
struct cred;

struct key_type;
struct key_owner;
struct key_tag;
struct keyring_list;
struct keyring_name;

struct key_tag {
	struct rcu_head		rcu;
	refcount_t		usage;
	bool			removed;	/* T when subject removed */
};

struct keyring_index_key {
	/* [!] If this structure is altered, the union in struct key must change too! */
	unsigned long		hash;			/* Hash value */
	union {
		struct {
#ifdef __LITTLE_ENDIAN /* Put desc_len at the LSB of x */
			u16	desc_len;
			char	desc[sizeof(long) - 2];	/* First few chars of description */
#else
			char	desc[sizeof(long) - 2];	/* First few chars of description */
			u16	desc_len;
#endif
		};
		unsigned long x;
	};
	struct key_type		*type;
	struct key_tag		*domain_tag;	/* Domain of operation */
	const char		*description;
};

union key_payload {
	void __rcu		*rcu_data0;
	void			*data[4];
};

/*****************************************************************************/
/*
 * key reference with possession attribute handling
 *
 * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually
 * defined. This is because we abuse the bottom bit of the reference to carry a
 * flag to indicate whether the calling process possesses that key in one of
 * its keyrings.
 *
 * the key_ref_t has been made a separate type so that the compiler can reject
 * attempts to dereference it without proper conversion.
 *
 * the three functions are used to assemble and disassemble references
 */
typedef struct __key_reference_with_attributes *key_ref_t;

static inline key_ref_t make_key_ref(const struct key *key,
				     bool possession)
{
	return (key_ref_t) ((unsigned long) key | possession);
}

static inline struct key *key_ref_to_ptr(const key_ref_t key_ref)
{
	return (struct key *) ((unsigned long) key_ref & ~1UL);
}

static inline bool is_key_possessed(const key_ref_t key_ref)
{
	return (unsigned long) key_ref & 1UL;
}

typedef int (*key_restrict_link_func_t)(struct key *dest_keyring,
					const struct key_type *type,
					const union key_payload *payload,
					struct key *restriction_key);

struct key_restriction {
	key_restrict_link_func_t check;
	struct key *key;
	struct key_type *keytype;
};

enum key_state {
	KEY_IS_UNINSTANTIATED,
	KEY_IS_POSITIVE,		/* Positively instantiated */
};

/*****************************************************************************/
/*
 * authentication token / access credential / keyring
 * - types of key include:
 *   - keyrings
 *   - disk encryption IDs
 *   - Kerberos TGTs and tickets
 */
struct key {
	refcount_t		usage;		/* number of references */
	key_serial_t		serial;		/* key serial number */
	union {
		struct list_head graveyard_link;
		struct rb_node	serial_node;
	};
#ifdef CONFIG_KEY_NOTIFICATIONS
	struct watch_list	*watchers;	/* Entities watching this key for changes */
#endif
	struct rw_semaphore	sem;		/* change vs change sem */
	struct key_user		*user;		/* owner of this key */
	void			*security;	/* security data for this key */
	union {
		time64_t	expiry;		/* time at which key expires (or 0) */
		time64_t	revoked_at;	/* time at which key was revoked */
	};
	time64_t		last_used_at;	/* last time used for LRU keyring discard */
	kuid_t			uid;
	kgid_t			gid;
	key_perm_t		perm;		/* access permissions */
	unsigned short		quotalen;	/* length added to quota */
	unsigned short		datalen;	/* payload data length
						 * - may not match RCU dereferenced payload
						 * - payload should contain own length
						 */
	short			state;		/* Key state (+) or rejection error (-) */

#ifdef KEY_DEBUGGING
	unsigned		magic;
#define KEY_DEBUG_MAGIC		0x18273645u
#endif

	unsigned long		flags;		/* status flags (change with bitops) */
#define KEY_FLAG_DEAD		0	/* set if key type has been deleted */
#define KEY_FLAG_REVOKED	1	/* set if key had been revoked */
#define KEY_FLAG_IN_QUOTA	2	/* set if key consumes quota */
#define KEY_FLAG_USER_CONSTRUCT	3	/* set if key is being constructed in userspace */
#define KEY_FLAG_ROOT_CAN_CLEAR	4	/* set if key can be cleared by root without permission */
#define KEY_FLAG_INVALIDATED	5	/* set if key has been invalidated */
#define KEY_FLAG_BUILTIN	6	/* set if key is built in to the kernel */
#define KEY_FLAG_ROOT_CAN_INVAL	7	/* set if key can be invalidated by root without permission */
#define KEY_FLAG_KEEP		8	/* set if key should not be removed */
#define KEY_FLAG_UID_KEYRING	9	/* set if key is a user or user session keyring */

	/* the key type and key description string
	 * - the desc is used to match a key against search criteria
	 * - it should be a printable string
	 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
	 */
	union {
		struct keyring_index_key index_key;
		struct {
			unsigned long	hash;
			unsigned long	len_desc;
			struct key_type	*type;		/* type of key */
			struct key_tag	*domain_tag;	/* Domain of operation */
			char		*description;
		};
	};

	/* key data
	 * - this is used to hold the data actually used in cryptography or
	 *   whatever
	 */
	union {
		union key_payload payload;
		struct {
			/* Keyring bits */
			struct list_head name_link;
			struct assoc_array keys;
		};
	};

	/* This is set on a keyring to restrict the addition of a link to a key
	 * to it.  If this structure isn't provided then it is assumed that the
	 * keyring is open to any addition.  It is ignored for non-keyring
	 * keys. Only set this value using keyring_restrict(), keyring_alloc(),
	 * or key_alloc().
	 *
	 * This is intended for use with rings of trusted keys whereby addition
	 * to the keyring needs to be controlled.  KEY_ALLOC_BYPASS_RESTRICTION
	 * overrides this, allowing the kernel to add extra keys without
	 * restriction.
	 */
	struct key_restriction *restrict_link;
};

extern struct key *key_alloc(struct key_type *type,
			     const char *desc,
			     kuid_t uid, kgid_t gid,
			     const struct cred *cred,
			     key_perm_t perm,
			     unsigned long flags,
			     struct key_restriction *restrict_link);


#define KEY_ALLOC_IN_QUOTA		0x0000	/* add to quota, reject if would overrun */
#define KEY_ALLOC_QUOTA_OVERRUN		0x0001	/* add to quota, permit even if overrun */
#define KEY_ALLOC_NOT_IN_QUOTA		0x0002	/* not in quota */
#define KEY_ALLOC_BUILT_IN		0x0004	/* Key is built into kernel */
#define KEY_ALLOC_BYPASS_RESTRICTION	0x0008	/* Override the check on restricted keyrings */
#define KEY_ALLOC_UID_KEYRING		0x0010	/* allocating a user or user session keyring */

extern void key_revoke(struct key *key);
extern void key_invalidate(struct key *key);
extern void key_put(struct key *key);
extern bool key_put_tag(struct key_tag *tag);
extern void key_remove_domain(struct key_tag *domain_tag);

static inline struct key *__key_get(struct key *key)
{
	refcount_inc(&key->usage);
	return key;
}

static inline struct key *key_get(struct key *key)
{
	return key ? __key_get(key) : key;
}

static inline void key_ref_put(key_ref_t key_ref)
{
	key_put(key_ref_to_ptr(key_ref));
}

extern struct key *request_key_tag(struct key_type *type,
				   const char *description,
				   struct key_tag *domain_tag,
				   const char *callout_info);

extern struct key *request_key_rcu(struct key_type *type,
				   const char *description,
				   struct key_tag *domain_tag);

extern struct key *request_key_with_auxdata(struct key_type *type,
					    const char *description,
					    struct key_tag *domain_tag,
					    const void *callout_info,
					    size_t callout_len,
					    void *aux);

/**
 * request_key - Request a key and wait for construction
 * @type: Type of key.
 * @description: The searchable description of the key.
 * @callout_info: The data to pass to the instantiation upcall (or NULL).
 *
 * As for request_key_tag(), but with the default global domain tag.
 */
static inline struct key *request_key(struct key_type *type,
				      const char *description,
				      const char *callout_info)
{
	return request_key_tag(type, description, NULL, callout_info);
}

#ifdef CONFIG_NET
/**
 * request_key_net - Request a key for a net namespace and wait for construction
 * @type: Type of key.
 * @description: The searchable description of the key.
 * @net: The network namespace that is the key's domain of operation.
 * @callout_info: The data to pass to the instantiation upcall (or NULL).
 *
 * As for request_key() except that it does not add the returned key to a
 * keyring if found, new keys are always allocated in the user's quota, the
 * callout_info must be a NUL-terminated string and no auxiliary data can be
 * passed.  Only keys that operate the specified network namespace are used.
 *
 * Furthermore, it then works as wait_for_key_construction() to wait for the
 * completion of keys undergoing construction with a non-interruptible wait.
 */
#define request_key_net(type, description, net, callout_info) \
	request_key_tag(type, description, net->key_domain, callout_info);

/**
 * request_key_net_rcu - Request a key for a net namespace under RCU conditions
 * @type: Type of key.
 * @description: The searchable description of the key.
 * @net: The network namespace that is the key's domain of operation.
 *
 * As for request_key_rcu() except that only keys that operate the specified
 * network namespace are used.
 */
#define request_key_net_rcu(type, description, net) \
	request_key_rcu(type, description, net->key_domain);
#endif /* CONFIG_NET */

extern int wait_for_key_construction(struct key *key, bool intr);

extern int key_validate(const struct key *key);

extern key_ref_t key_create_or_update(key_ref_t keyring,
				      const char *type,
				      const char *description,
				      const void *payload,
				      size_t plen,
				      key_perm_t perm,
				      unsigned long flags);

extern int key_update(key_ref_t key,
		      const void *payload,
		      size_t plen);

extern int key_link(struct key *keyring,
		    struct key *key);

extern int key_move(struct key *key,
		    struct key *from_keyring,
		    struct key *to_keyring,
		    unsigned int flags);

extern int key_unlink(struct key *keyring,
		      struct key *key);

extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
				 const struct cred *cred,
				 key_perm_t perm,
				 unsigned long flags,
				 struct key_restriction *restrict_link,
				 struct key *dest);

extern int restrict_link_reject(struct key *keyring,
				const struct key_type *type,
				const union key_payload *payload,
				struct key *restriction_key);

extern int keyring_clear(struct key *keyring);

extern key_ref_t keyring_search(key_ref_t keyring,
				struct key_type *type,
				const char *description,
				bool recurse);

extern int keyring_add_key(struct key *keyring,
			   struct key *key);

extern int keyring_restrict(key_ref_t keyring, const char *type,
			    const char *restriction);

extern struct key *key_lookup(key_serial_t id);

static inline key_serial_t key_serial(const struct key *key)
{
	return key ? key->serial : 0;
}

extern void key_set_timeout(struct key *, unsigned);

extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
				 enum key_need_perm need_perm);
extern void key_free_user_ns(struct user_namespace *);

static inline short key_read_state(const struct key *key)
{
	/* Barrier versus mark_key_instantiated(). */
	return smp_load_acquire(&key->state);
}

/**
 * key_is_positive - Determine if a key has been positively instantiated
 * @key: The key to check.
 *
 * Return true if the specified key has been positively instantiated, false
 * otherwise.
 */
static inline bool key_is_positive(const struct key *key)
{
	return key_read_state(key) == KEY_IS_POSITIVE;
}

static inline bool key_is_negative(const struct key *key)
{
	return key_read_state(key) < 0;
}

#define dereference_key_rcu(KEY)					\
	(rcu_dereference((KEY)->payload.rcu_data0))

#define dereference_key_locked(KEY)					\
	(rcu_dereference_protected((KEY)->payload.rcu_data0,		\
				   rwsem_is_locked(&((struct key *)(KEY))->sem)))

#define rcu_assign_keypointer(KEY, PAYLOAD)				\
do {									\
	rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD));	\
} while (0)

#ifdef CONFIG_SYSCTL
extern struct ctl_table key_sysctls[];
#endif
/*
 * the userspace interface
 */
extern int install_thread_keyring_to_cred(struct cred *cred);
extern void key_fsuid_changed(struct cred *new_cred);
extern void key_fsgid_changed(struct cred *new_cred);
extern void key_init(void);

#else /* CONFIG_KEYS */

#define key_validate(k)			0
#define key_serial(k)			0
#define key_get(k) 			({ NULL; })
#define key_revoke(k)			do { } while(0)
#define key_invalidate(k)		do { } while(0)
#define key_put(k)			do { } while(0)
#define key_ref_put(k)			do { } while(0)
#define make_key_ref(k, p)		NULL
#define key_ref_to_ptr(k)		NULL
#define is_key_possessed(k)		0
#define key_fsuid_changed(c)		do { } while(0)
#define key_fsgid_changed(c)		do { } while(0)
#define key_init()			do { } while(0)
#define key_free_user_ns(ns)		do { } while(0)
#define key_remove_domain(d)		do { } while(0)

#endif /* CONFIG_KEYS */
#endif /* __KERNEL__ */
#endif /* _LINUX_KEY_H */