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1 /* Definitions for key type implementations
2  *
3  * Copyright (C) 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 Licence
8  * as published by the Free Software Foundation; either version
9  * 2 of the Licence, or (at your option) any later version.
10  */
11 
12 #ifndef _LINUX_KEY_TYPE_H
13 #define _LINUX_KEY_TYPE_H
14 
15 #include <linux/key.h>
16 #include <linux/errno.h>
17 
18 #ifdef CONFIG_KEYS
19 
20 /*
21  * key under-construction record
22  * - passed to the request_key actor if supplied
23  */
24 struct key_construction {
25 	struct key	*key;	/* key being constructed */
26 	struct key	*authkey;/* authorisation for key being constructed */
27 };
28 
29 /*
30  * Pre-parsed payload, used by key add, update and instantiate.
31  *
32  * This struct will be cleared and data and datalen will be set with the data
33  * and length parameters from the caller and quotalen will be set from
34  * def_datalen from the key type.  Then if the preparse() op is provided by the
35  * key type, that will be called.  Then the struct will be passed to the
36  * instantiate() or the update() op.
37  *
38  * If the preparse() op is given, the free_preparse() op will be called to
39  * clear the contents.
40  */
41 struct key_preparsed_payload {
42 	char		*description;	/* Proposed key description (or NULL) */
43 	void		*type_data[2];	/* Private key-type data */
44 	void		*payload[2];	/* Proposed payload */
45 	const void	*data;		/* Raw data */
46 	size_t		datalen;	/* Raw datalen */
47 	size_t		quotalen;	/* Quota length for proposed payload */
48 	time_t		expiry;		/* Expiry time of key */
49 	bool		trusted;	/* True if key is trusted */
50 };
51 
52 typedef int (*request_key_actor_t)(struct key_construction *key,
53 				   const char *op, void *aux);
54 
55 /*
56  * Preparsed matching criterion.
57  */
58 struct key_match_data {
59 	/* Comparison function, defaults to exact description match, but can be
60 	 * overridden by type->match_preparse().  Should return true if a match
61 	 * is found and false if not.
62 	 */
63 	bool (*cmp)(const struct key *key,
64 		    const struct key_match_data *match_data);
65 
66 	const void	*raw_data;	/* Raw match data */
67 	void		*preparsed;	/* For ->match_preparse() to stash stuff */
68 	unsigned	lookup_type;	/* Type of lookup for this search. */
69 #define KEYRING_SEARCH_LOOKUP_DIRECT	0x0000	/* Direct lookup by description. */
70 #define KEYRING_SEARCH_LOOKUP_ITERATE	0x0001	/* Iterative search. */
71 };
72 
73 /*
74  * kernel managed key type definition
75  */
76 struct key_type {
77 	/* name of the type */
78 	const char *name;
79 
80 	/* default payload length for quota precalculation (optional)
81 	 * - this can be used instead of calling key_payload_reserve(), that
82 	 *   function only needs to be called if the real datalen is different
83 	 */
84 	size_t def_datalen;
85 
86 	/* vet a description */
87 	int (*vet_description)(const char *description);
88 
89 	/* Preparse the data blob from userspace that is to be the payload,
90 	 * generating a proposed description and payload that will be handed to
91 	 * the instantiate() and update() ops.
92 	 */
93 	int (*preparse)(struct key_preparsed_payload *prep);
94 
95 	/* Free a preparse data structure.
96 	 */
97 	void (*free_preparse)(struct key_preparsed_payload *prep);
98 
99 	/* instantiate a key of this type
100 	 * - this method should call key_payload_reserve() to determine if the
101 	 *   user's quota will hold the payload
102 	 */
103 	int (*instantiate)(struct key *key, struct key_preparsed_payload *prep);
104 
105 	/* update a key of this type (optional)
106 	 * - this method should call key_payload_reserve() to recalculate the
107 	 *   quota consumption
108 	 * - the key must be locked against read when modifying
109 	 */
110 	int (*update)(struct key *key, struct key_preparsed_payload *prep);
111 
112 	/* Preparse the data supplied to ->match() (optional).  The
113 	 * data to be preparsed can be found in match_data->raw_data.
114 	 * The lookup type can also be set by this function.
115 	 */
116 	int (*match_preparse)(struct key_match_data *match_data);
117 
118 	/* Free preparsed match data (optional).  This should be supplied it
119 	 * ->match_preparse() is supplied. */
120 	void (*match_free)(struct key_match_data *match_data);
121 
122 	/* clear some of the data from a key on revokation (optional)
123 	 * - the key's semaphore will be write-locked by the caller
124 	 */
125 	void (*revoke)(struct key *key);
126 
127 	/* clear the data from a key (optional) */
128 	void (*destroy)(struct key *key);
129 
130 	/* describe a key */
131 	void (*describe)(const struct key *key, struct seq_file *p);
132 
133 	/* read a key's data (optional)
134 	 * - permission checks will be done by the caller
135 	 * - the key's semaphore will be readlocked by the caller
136 	 * - should return the amount of data that could be read, no matter how
137 	 *   much is copied into the buffer
138 	 * - shouldn't do the copy if the buffer is NULL
139 	 */
140 	long (*read)(const struct key *key, char __user *buffer, size_t buflen);
141 
142 	/* handle request_key() for this type instead of invoking
143 	 * /sbin/request-key (optional)
144 	 * - key is the key to instantiate
145 	 * - authkey is the authority to assume when instantiating this key
146 	 * - op is the operation to be done, usually "create"
147 	 * - the call must not return until the instantiation process has run
148 	 *   its course
149 	 */
150 	request_key_actor_t request_key;
151 
152 	/* internal fields */
153 	struct list_head	link;		/* link in types list */
154 	struct lock_class_key	lock_class;	/* key->sem lock class */
155 };
156 
157 extern struct key_type key_type_keyring;
158 
159 extern int register_key_type(struct key_type *ktype);
160 extern void unregister_key_type(struct key_type *ktype);
161 
162 extern int key_payload_reserve(struct key *key, size_t datalen);
163 extern int key_instantiate_and_link(struct key *key,
164 				    const void *data,
165 				    size_t datalen,
166 				    struct key *keyring,
167 				    struct key *instkey);
168 extern int key_reject_and_link(struct key *key,
169 			       unsigned timeout,
170 			       unsigned error,
171 			       struct key *keyring,
172 			       struct key *instkey);
173 extern void complete_request_key(struct key_construction *cons, int error);
174 
key_negate_and_link(struct key * key,unsigned timeout,struct key * keyring,struct key * instkey)175 static inline int key_negate_and_link(struct key *key,
176 				      unsigned timeout,
177 				      struct key *keyring,
178 				      struct key *instkey)
179 {
180 	return key_reject_and_link(key, timeout, ENOKEY, keyring, instkey);
181 }
182 
183 extern int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep);
184 
185 #endif /* CONFIG_KEYS */
186 #endif /* _LINUX_KEY_TYPE_H */
187