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/core.rst 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 | #include <linux/refcount.h> |
27 | #include <linux/time64.h> |
28 | |
29 | #ifdef __KERNEL__ |
30 | #include <linux/uidgid.h> |
31 | |
32 | /* key handle serial number */ |
33 | typedef int32_t key_serial_t; |
34 | |
35 | /* key handle permissions mask */ |
36 | typedef uint32_t key_perm_t; |
37 | |
38 | struct key; |
39 | |
40 | #ifdef CONFIG_KEYS |
41 | |
42 | #undef KEY_DEBUGGING |
43 | |
44 | #define KEY_POS_VIEW 0x01000000 /* possessor can view a key's attributes */ |
45 | #define KEY_POS_READ 0x02000000 /* possessor can read key payload / view keyring */ |
46 | #define KEY_POS_WRITE 0x04000000 /* possessor can update key payload / add link to keyring */ |
47 | #define KEY_POS_SEARCH 0x08000000 /* possessor can find a key in search / search a keyring */ |
48 | #define KEY_POS_LINK 0x10000000 /* possessor can create a link to a key/keyring */ |
49 | #define KEY_POS_SETATTR 0x20000000 /* possessor can set key attributes */ |
50 | #define KEY_POS_ALL 0x3f000000 |
51 | |
52 | #define KEY_USR_VIEW 0x00010000 /* user permissions... */ |
53 | #define KEY_USR_READ 0x00020000 |
54 | #define KEY_USR_WRITE 0x00040000 |
55 | #define KEY_USR_SEARCH 0x00080000 |
56 | #define KEY_USR_LINK 0x00100000 |
57 | #define KEY_USR_SETATTR 0x00200000 |
58 | #define KEY_USR_ALL 0x003f0000 |
59 | |
60 | #define KEY_GRP_VIEW 0x00000100 /* group permissions... */ |
61 | #define KEY_GRP_READ 0x00000200 |
62 | #define KEY_GRP_WRITE 0x00000400 |
63 | #define KEY_GRP_SEARCH 0x00000800 |
64 | #define KEY_GRP_LINK 0x00001000 |
65 | #define KEY_GRP_SETATTR 0x00002000 |
66 | #define KEY_GRP_ALL 0x00003f00 |
67 | |
68 | #define KEY_OTH_VIEW 0x00000001 /* third party permissions... */ |
69 | #define KEY_OTH_READ 0x00000002 |
70 | #define KEY_OTH_WRITE 0x00000004 |
71 | #define KEY_OTH_SEARCH 0x00000008 |
72 | #define KEY_OTH_LINK 0x00000010 |
73 | #define KEY_OTH_SETATTR 0x00000020 |
74 | #define KEY_OTH_ALL 0x0000003f |
75 | |
76 | #define KEY_PERM_UNDEF 0xffffffff |
77 | |
78 | struct seq_file; |
79 | struct user_struct; |
80 | struct signal_struct; |
81 | struct cred; |
82 | |
83 | struct key_type; |
84 | struct key_owner; |
85 | struct keyring_list; |
86 | struct keyring_name; |
87 | |
88 | struct keyring_index_key { |
89 | struct key_type *type; |
90 | const char *description; |
91 | size_t desc_len; |
92 | }; |
93 | |
94 | union key_payload { |
95 | void __rcu *rcu_data0; |
96 | void *data[4]; |
97 | }; |
98 | |
99 | /*****************************************************************************/ |
100 | /* |
101 | * key reference with possession attribute handling |
102 | * |
103 | * NOTE! key_ref_t is a typedef'd pointer to a type that is not actually |
104 | * defined. This is because we abuse the bottom bit of the reference to carry a |
105 | * flag to indicate whether the calling process possesses that key in one of |
106 | * its keyrings. |
107 | * |
108 | * the key_ref_t has been made a separate type so that the compiler can reject |
109 | * attempts to dereference it without proper conversion. |
110 | * |
111 | * the three functions are used to assemble and disassemble references |
112 | */ |
113 | typedef struct __key_reference_with_attributes *key_ref_t; |
114 | |
115 | static inline key_ref_t make_key_ref(const struct key *key, |
116 | bool possession) |
117 | { |
118 | return (key_ref_t) ((unsigned long) key | possession); |
119 | } |
120 | |
121 | static inline struct key *key_ref_to_ptr(const key_ref_t key_ref) |
122 | { |
123 | return (struct key *) ((unsigned long) key_ref & ~1UL); |
124 | } |
125 | |
126 | static inline bool is_key_possessed(const key_ref_t key_ref) |
127 | { |
128 | return (unsigned long) key_ref & 1UL; |
129 | } |
130 | |
131 | typedef int (*key_restrict_link_func_t)(struct key *dest_keyring, |
132 | const struct key_type *type, |
133 | const union key_payload *payload, |
134 | struct key *restriction_key); |
135 | |
136 | struct key_restriction { |
137 | key_restrict_link_func_t check; |
138 | struct key *key; |
139 | struct key_type *keytype; |
140 | }; |
141 | |
142 | enum key_state { |
143 | KEY_IS_UNINSTANTIATED, |
144 | KEY_IS_POSITIVE, /* Positively instantiated */ |
145 | }; |
146 | |
147 | /*****************************************************************************/ |
148 | /* |
149 | * authentication token / access credential / keyring |
150 | * - types of key include: |
151 | * - keyrings |
152 | * - disk encryption IDs |
153 | * - Kerberos TGTs and tickets |
154 | */ |
155 | struct key { |
156 | refcount_t usage; /* number of references */ |
157 | key_serial_t serial; /* key serial number */ |
158 | union { |
159 | struct list_head graveyard_link; |
160 | struct rb_node serial_node; |
161 | }; |
162 | struct rw_semaphore sem; /* change vs change sem */ |
163 | struct key_user *user; /* owner of this key */ |
164 | void *security; /* security data for this key */ |
165 | union { |
166 | time64_t expiry; /* time at which key expires (or 0) */ |
167 | time64_t revoked_at; /* time at which key was revoked */ |
168 | }; |
169 | time64_t last_used_at; /* last time used for LRU keyring discard */ |
170 | kuid_t uid; |
171 | kgid_t gid; |
172 | key_perm_t perm; /* access permissions */ |
173 | unsigned short quotalen; /* length added to quota */ |
174 | unsigned short datalen; /* payload data length |
175 | * - may not match RCU dereferenced payload |
176 | * - payload should contain own length |
177 | */ |
178 | short state; /* Key state (+) or rejection error (-) */ |
179 | |
180 | #ifdef KEY_DEBUGGING |
181 | unsigned magic; |
182 | #define KEY_DEBUG_MAGIC 0x18273645u |
183 | #endif |
184 | |
185 | unsigned long flags; /* status flags (change with bitops) */ |
186 | #define KEY_FLAG_DEAD 0 /* set if key type has been deleted */ |
187 | #define KEY_FLAG_REVOKED 1 /* set if key had been revoked */ |
188 | #define KEY_FLAG_IN_QUOTA 2 /* set if key consumes quota */ |
189 | #define KEY_FLAG_USER_CONSTRUCT 3 /* set if key is being constructed in userspace */ |
190 | #define KEY_FLAG_ROOT_CAN_CLEAR 4 /* set if key can be cleared by root without permission */ |
191 | #define KEY_FLAG_INVALIDATED 5 /* set if key has been invalidated */ |
192 | #define KEY_FLAG_BUILTIN 6 /* set if key is built in to the kernel */ |
193 | #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */ |
194 | #define KEY_FLAG_KEEP 8 /* set if key should not be removed */ |
195 | #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */ |
196 | |
197 | /* the key type and key description string |
198 | * - the desc is used to match a key against search criteria |
199 | * - it should be a printable string |
200 | * - eg: for krb5 AFS, this might be "afs@REDHAT.COM" |
201 | */ |
202 | union { |
203 | struct keyring_index_key index_key; |
204 | struct { |
205 | struct key_type *type; /* type of key */ |
206 | char *description; |
207 | }; |
208 | }; |
209 | |
210 | /* key data |
211 | * - this is used to hold the data actually used in cryptography or |
212 | * whatever |
213 | */ |
214 | union { |
215 | union key_payload payload; |
216 | struct { |
217 | /* Keyring bits */ |
218 | struct list_head name_link; |
219 | struct assoc_array keys; |
220 | }; |
221 | }; |
222 | |
223 | /* This is set on a keyring to restrict the addition of a link to a key |
224 | * to it. If this structure isn't provided then it is assumed that the |
225 | * keyring is open to any addition. It is ignored for non-keyring |
226 | * keys. Only set this value using keyring_restrict(), keyring_alloc(), |
227 | * or key_alloc(). |
228 | * |
229 | * This is intended for use with rings of trusted keys whereby addition |
230 | * to the keyring needs to be controlled. KEY_ALLOC_BYPASS_RESTRICTION |
231 | * overrides this, allowing the kernel to add extra keys without |
232 | * restriction. |
233 | */ |
234 | struct key_restriction *restrict_link; |
235 | }; |
236 | |
237 | extern struct key *key_alloc(struct key_type *type, |
238 | const char *desc, |
239 | kuid_t uid, kgid_t gid, |
240 | const struct cred *cred, |
241 | key_perm_t perm, |
242 | unsigned long flags, |
243 | struct key_restriction *restrict_link); |
244 | |
245 | |
246 | #define KEY_ALLOC_IN_QUOTA 0x0000 /* add to quota, reject if would overrun */ |
247 | #define KEY_ALLOC_QUOTA_OVERRUN 0x0001 /* add to quota, permit even if overrun */ |
248 | #define KEY_ALLOC_NOT_IN_QUOTA 0x0002 /* not in quota */ |
249 | #define KEY_ALLOC_BUILT_IN 0x0004 /* Key is built into kernel */ |
250 | #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */ |
251 | #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */ |
252 | |
253 | extern void key_revoke(struct key *key); |
254 | extern void key_invalidate(struct key *key); |
255 | extern void key_put(struct key *key); |
256 | |
257 | static inline struct key *__key_get(struct key *key) |
258 | { |
259 | refcount_inc(&key->usage); |
260 | return key; |
261 | } |
262 | |
263 | static inline struct key *key_get(struct key *key) |
264 | { |
265 | return key ? __key_get(key) : key; |
266 | } |
267 | |
268 | static inline void key_ref_put(key_ref_t key_ref) |
269 | { |
270 | key_put(key_ref_to_ptr(key_ref)); |
271 | } |
272 | |
273 | extern struct key *request_key(struct key_type *type, |
274 | const char *description, |
275 | const char *callout_info); |
276 | |
277 | extern struct key *request_key_with_auxdata(struct key_type *type, |
278 | const char *description, |
279 | const void *callout_info, |
280 | size_t callout_len, |
281 | void *aux); |
282 | |
283 | extern struct key *request_key_async(struct key_type *type, |
284 | const char *description, |
285 | const void *callout_info, |
286 | size_t callout_len); |
287 | |
288 | extern struct key *request_key_async_with_auxdata(struct key_type *type, |
289 | const char *description, |
290 | const void *callout_info, |
291 | size_t callout_len, |
292 | void *aux); |
293 | |
294 | extern int wait_for_key_construction(struct key *key, bool intr); |
295 | |
296 | extern int key_validate(const struct key *key); |
297 | |
298 | extern 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 | key_perm_t perm, |
304 | unsigned long flags); |
305 | |
306 | extern int key_update(key_ref_t key, |
307 | const void *payload, |
308 | size_t plen); |
309 | |
310 | extern int key_link(struct key *keyring, |
311 | struct key *key); |
312 | |
313 | extern int key_unlink(struct key *keyring, |
314 | struct key *key); |
315 | |
316 | extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, |
317 | const struct cred *cred, |
318 | key_perm_t perm, |
319 | unsigned long flags, |
320 | struct key_restriction *restrict_link, |
321 | struct key *dest); |
322 | |
323 | extern int restrict_link_reject(struct key *keyring, |
324 | const struct key_type *type, |
325 | const union key_payload *payload, |
326 | struct key *restriction_key); |
327 | |
328 | extern int keyring_clear(struct key *keyring); |
329 | |
330 | extern key_ref_t keyring_search(key_ref_t keyring, |
331 | struct key_type *type, |
332 | const char *description); |
333 | |
334 | extern int keyring_add_key(struct key *keyring, |
335 | struct key *key); |
336 | |
337 | extern int keyring_restrict(key_ref_t keyring, const char *type, |
338 | const char *restriction); |
339 | |
340 | extern struct key *key_lookup(key_serial_t id); |
341 | |
342 | static inline key_serial_t key_serial(const struct key *key) |
343 | { |
344 | return key ? key->serial : 0; |
345 | } |
346 | |
347 | extern void key_set_timeout(struct key *, unsigned); |
348 | |
349 | extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags, |
350 | key_perm_t perm); |
351 | |
352 | /* |
353 | * The permissions required on a key that we're looking up. |
354 | */ |
355 | #define KEY_NEED_VIEW 0x01 /* Require permission to view attributes */ |
356 | #define KEY_NEED_READ 0x02 /* Require permission to read content */ |
357 | #define KEY_NEED_WRITE 0x04 /* Require permission to update / modify */ |
358 | #define KEY_NEED_SEARCH 0x08 /* Require permission to search (keyring) or find (key) */ |
359 | #define KEY_NEED_LINK 0x10 /* Require permission to link */ |
360 | #define KEY_NEED_SETATTR 0x20 /* Require permission to change attributes */ |
361 | #define KEY_NEED_ALL 0x3f /* All the above permissions */ |
362 | |
363 | static inline short key_read_state(const struct key *key) |
364 | { |
365 | /* Barrier versus mark_key_instantiated(). */ |
366 | return smp_load_acquire(&key->state); |
367 | } |
368 | |
369 | /** |
370 | * key_is_positive - Determine if a key has been positively instantiated |
371 | * @key: The key to check. |
372 | * |
373 | * Return true if the specified key has been positively instantiated, false |
374 | * otherwise. |
375 | */ |
376 | static inline bool key_is_positive(const struct key *key) |
377 | { |
378 | return key_read_state(key) == KEY_IS_POSITIVE; |
379 | } |
380 | |
381 | static inline bool key_is_negative(const struct key *key) |
382 | { |
383 | return key_read_state(key) < 0; |
384 | } |
385 | |
386 | #define dereference_key_rcu(KEY) \ |
387 | (rcu_dereference((KEY)->payload.rcu_data0)) |
388 | |
389 | #define dereference_key_locked(KEY) \ |
390 | (rcu_dereference_protected((KEY)->payload.rcu_data0, \ |
391 | rwsem_is_locked(&((struct key *)(KEY))->sem))) |
392 | |
393 | #define rcu_assign_keypointer(KEY, PAYLOAD) \ |
394 | do { \ |
395 | rcu_assign_pointer((KEY)->payload.rcu_data0, (PAYLOAD)); \ |
396 | } while (0) |
397 | |
398 | #ifdef CONFIG_SYSCTL |
399 | extern struct ctl_table key_sysctls[]; |
400 | #endif |
401 | /* |
402 | * the userspace interface |
403 | */ |
404 | extern int install_thread_keyring_to_cred(struct cred *cred); |
405 | extern void key_fsuid_changed(struct task_struct *tsk); |
406 | extern void key_fsgid_changed(struct task_struct *tsk); |
407 | extern void key_init(void); |
408 | |
409 | #else /* CONFIG_KEYS */ |
410 | |
411 | #define key_validate(k) 0 |
412 | #define key_serial(k) 0 |
413 | #define key_get(k) ({ NULL; }) |
414 | #define key_revoke(k) do { } while(0) |
415 | #define key_invalidate(k) do { } while(0) |
416 | #define key_put(k) do { } while(0) |
417 | #define key_ref_put(k) do { } while(0) |
418 | #define make_key_ref(k, p) NULL |
419 | #define key_ref_to_ptr(k) NULL |
420 | #define is_key_possessed(k) 0 |
421 | #define key_fsuid_changed(t) do { } while(0) |
422 | #define key_fsgid_changed(t) do { } while(0) |
423 | #define key_init() do { } while(0) |
424 | |
425 | #endif /* CONFIG_KEYS */ |
426 | #endif /* __KERNEL__ */ |
427 | #endif /* _LINUX_KEY_H */ |
428 | |