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69664cf1 1/* Keyring handling
1da177e4 2 *
b2a4df20 3 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
1da177e4
LT
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#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
29db9190 16#include <linux/security.h>
1da177e4
LT
17#include <linux/seq_file.h>
18#include <linux/err.h>
e9e349b0 19#include <keys/keyring-type.h>
b2a4df20
DH
20#include <keys/user-type.h>
21#include <linux/assoc_array_priv.h>
512ea3bc 22#include <linux/uaccess.h>
1da177e4
LT
23#include "internal.h"
24
25/*
973c9f4f
DH
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
1da177e4
LT
28 */
29#define KEYRING_SEARCH_MAX_DEPTH 6
30
31/*
973c9f4f 32 * We keep all named keyrings in a hash to speed looking them up.
1da177e4
LT
33 */
34#define KEYRING_NAME_HASH_SIZE (1 << 5)
35
b2a4df20
DH
36/*
37 * We mark pointers we pass to the associative array with bit 1 set if
38 * they're keyrings and clear otherwise.
39 */
40#define KEYRING_PTR_SUBTYPE 0x2UL
41
42static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
43{
44 return (unsigned long)x & KEYRING_PTR_SUBTYPE;
45}
46static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
47{
48 void *object = assoc_array_ptr_to_leaf(x);
49 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
50}
51static inline void *keyring_key_to_ptr(struct key *key)
52{
53 if (key->type == &key_type_keyring)
54 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
55 return key;
56}
57
1da177e4
LT
58static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
59static DEFINE_RWLOCK(keyring_name_lock);
60
61static inline unsigned keyring_hash(const char *desc)
62{
63 unsigned bucket = 0;
64
65 for (; *desc; desc++)
c5b60b5e 66 bucket += (unsigned char)*desc;
1da177e4
LT
67
68 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
69}
70
71/*
973c9f4f
DH
72 * The keyring key type definition. Keyrings are simply keys of this type and
73 * can be treated as ordinary keys in addition to having their own special
74 * operations.
1da177e4 75 */
5d19e20b
DH
76static int keyring_preparse(struct key_preparsed_payload *prep);
77static void keyring_free_preparse(struct key_preparsed_payload *prep);
1da177e4 78static int keyring_instantiate(struct key *keyring,
cf7f601c 79 struct key_preparsed_payload *prep);
31204ed9 80static void keyring_revoke(struct key *keyring);
1da177e4
LT
81static void keyring_destroy(struct key *keyring);
82static void keyring_describe(const struct key *keyring, struct seq_file *m);
83static long keyring_read(const struct key *keyring,
84 char __user *buffer, size_t buflen);
85
86struct key_type key_type_keyring = {
87 .name = "keyring",
b2a4df20 88 .def_datalen = 0,
5d19e20b
DH
89 .preparse = keyring_preparse,
90 .free_preparse = keyring_free_preparse,
1da177e4 91 .instantiate = keyring_instantiate,
31204ed9 92 .revoke = keyring_revoke,
1da177e4
LT
93 .destroy = keyring_destroy,
94 .describe = keyring_describe,
95 .read = keyring_read,
96};
7318226e
DH
97EXPORT_SYMBOL(key_type_keyring);
98
1da177e4 99/*
973c9f4f
DH
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
1da177e4 102 */
1ae8f407 103static DECLARE_RWSEM(keyring_serialise_link_sem);
1da177e4 104
1da177e4 105/*
973c9f4f
DH
106 * Publish the name of a keyring so that it can be found by name (if it has
107 * one).
1da177e4 108 */
69664cf1 109static void keyring_publish_name(struct key *keyring)
1da177e4
LT
110{
111 int bucket;
112
113 if (keyring->description) {
114 bucket = keyring_hash(keyring->description);
115
116 write_lock(&keyring_name_lock);
117
118 if (!keyring_name_hash[bucket].next)
119 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
120
146aa8b1 121 list_add_tail(&keyring->name_link,
1da177e4
LT
122 &keyring_name_hash[bucket]);
123
124 write_unlock(&keyring_name_lock);
125 }
a8b17ed0 126}
1da177e4 127
5d19e20b
DH
128/*
129 * Preparse a keyring payload
130 */
131static int keyring_preparse(struct key_preparsed_payload *prep)
132{
133 return prep->datalen != 0 ? -EINVAL : 0;
134}
135
136/*
137 * Free a preparse of a user defined key payload
138 */
139static void keyring_free_preparse(struct key_preparsed_payload *prep)
140{
141}
142
1da177e4 143/*
973c9f4f
DH
144 * Initialise a keyring.
145 *
146 * Returns 0 on success, -EINVAL if given any data.
1da177e4
LT
147 */
148static int keyring_instantiate(struct key *keyring,
cf7f601c 149 struct key_preparsed_payload *prep)
1da177e4 150{
5d19e20b
DH
151 assoc_array_init(&keyring->keys);
152 /* make the keyring available by name if it has one */
153 keyring_publish_name(keyring);
154 return 0;
a8b17ed0 155}
1da177e4 156
1da177e4 157/*
b2a4df20
DH
158 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
159 * fold the carry back too, but that requires inline asm.
160 */
161static u64 mult_64x32_and_fold(u64 x, u32 y)
162{
163 u64 hi = (u64)(u32)(x >> 32) * y;
164 u64 lo = (u64)(u32)(x) * y;
165 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
166}
167
168/*
169 * Hash a key type and description.
170 */
171static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key)
172{
173 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
d54e58b7 174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
b2a4df20
DH
175 const char *description = index_key->description;
176 unsigned long hash, type;
177 u32 piece;
178 u64 acc;
179 int n, desc_len = index_key->desc_len;
180
181 type = (unsigned long)index_key->type;
182
183 acc = mult_64x32_and_fold(type, desc_len + 13);
184 acc = mult_64x32_and_fold(acc, 9207);
185 for (;;) {
186 n = desc_len;
187 if (n <= 0)
188 break;
189 if (n > 4)
190 n = 4;
191 piece = 0;
192 memcpy(&piece, description, n);
193 description += n;
194 desc_len -= n;
195 acc = mult_64x32_and_fold(acc, piece);
196 acc = mult_64x32_and_fold(acc, 9207);
197 }
198
199 /* Fold the hash down to 32 bits if need be. */
200 hash = acc;
201 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
202 hash ^= acc >> 32;
203
204 /* Squidge all the keyrings into a separate part of the tree to
205 * ordinary keys by making sure the lowest level segment in the hash is
206 * zero for keyrings and non-zero otherwise.
207 */
d54e58b7 208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
b2a4df20 209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
d54e58b7
DH
210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
211 return (hash + (hash << level_shift)) & ~fan_mask;
b2a4df20
DH
212 return hash;
213}
214
215/*
216 * Build the next index key chunk.
217 *
218 * On 32-bit systems the index key is laid out as:
219 *
220 * 0 4 5 9...
221 * hash desclen typeptr desc[]
222 *
223 * On 64-bit systems:
224 *
225 * 0 8 9 17...
226 * hash desclen typeptr desc[]
227 *
228 * We return it one word-sized chunk at a time.
1da177e4 229 */
b2a4df20
DH
230static unsigned long keyring_get_key_chunk(const void *data, int level)
231{
232 const struct keyring_index_key *index_key = data;
233 unsigned long chunk = 0;
234 long offset = 0;
235 int desc_len = index_key->desc_len, n = sizeof(chunk);
236
237 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
238 switch (level) {
239 case 0:
240 return hash_key_type_and_desc(index_key);
241 case 1:
242 return ((unsigned long)index_key->type << 8) | desc_len;
243 case 2:
244 if (desc_len == 0)
245 return (u8)((unsigned long)index_key->type >>
246 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
247 n--;
248 offset = 1;
249 default:
250 offset += sizeof(chunk) - 1;
251 offset += (level - 3) * sizeof(chunk);
252 if (offset >= desc_len)
253 return 0;
254 desc_len -= offset;
255 if (desc_len > n)
256 desc_len = n;
257 offset += desc_len;
258 do {
259 chunk <<= 8;
260 chunk |= ((u8*)index_key->description)[--offset];
261 } while (--desc_len > 0);
262
263 if (level == 2) {
264 chunk <<= 8;
265 chunk |= (u8)((unsigned long)index_key->type >>
266 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
267 }
268 return chunk;
269 }
270}
271
272static unsigned long keyring_get_object_key_chunk(const void *object, int level)
273{
274 const struct key *key = keyring_ptr_to_key(object);
275 return keyring_get_key_chunk(&key->index_key, level);
276}
277
278static bool keyring_compare_object(const void *object, const void *data)
1da177e4 279{
b2a4df20
DH
280 const struct keyring_index_key *index_key = data;
281 const struct key *key = keyring_ptr_to_key(object);
282
283 return key->index_key.type == index_key->type &&
284 key->index_key.desc_len == index_key->desc_len &&
285 memcmp(key->index_key.description, index_key->description,
286 index_key->desc_len) == 0;
a8b17ed0 287}
1da177e4 288
b2a4df20
DH
289/*
290 * Compare the index keys of a pair of objects and determine the bit position
291 * at which they differ - if they differ.
292 */
23fd78d7 293static int keyring_diff_objects(const void *object, const void *data)
b2a4df20 294{
23fd78d7 295 const struct key *key_a = keyring_ptr_to_key(object);
b2a4df20 296 const struct keyring_index_key *a = &key_a->index_key;
23fd78d7 297 const struct keyring_index_key *b = data;
b2a4df20
DH
298 unsigned long seg_a, seg_b;
299 int level, i;
300
301 level = 0;
302 seg_a = hash_key_type_and_desc(a);
303 seg_b = hash_key_type_and_desc(b);
304 if ((seg_a ^ seg_b) != 0)
305 goto differ;
306
307 /* The number of bits contributed by the hash is controlled by a
308 * constant in the assoc_array headers. Everything else thereafter we
309 * can deal with as being machine word-size dependent.
310 */
311 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
312 seg_a = a->desc_len;
313 seg_b = b->desc_len;
314 if ((seg_a ^ seg_b) != 0)
315 goto differ;
316
317 /* The next bit may not work on big endian */
318 level++;
319 seg_a = (unsigned long)a->type;
320 seg_b = (unsigned long)b->type;
321 if ((seg_a ^ seg_b) != 0)
322 goto differ;
323
324 level += sizeof(unsigned long);
325 if (a->desc_len == 0)
326 goto same;
327
328 i = 0;
329 if (((unsigned long)a->description | (unsigned long)b->description) &
330 (sizeof(unsigned long) - 1)) {
331 do {
332 seg_a = *(unsigned long *)(a->description + i);
333 seg_b = *(unsigned long *)(b->description + i);
334 if ((seg_a ^ seg_b) != 0)
335 goto differ_plus_i;
336 i += sizeof(unsigned long);
337 } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
338 }
339
340 for (; i < a->desc_len; i++) {
341 seg_a = *(unsigned char *)(a->description + i);
342 seg_b = *(unsigned char *)(b->description + i);
343 if ((seg_a ^ seg_b) != 0)
344 goto differ_plus_i;
345 }
346
347same:
348 return -1;
349
350differ_plus_i:
351 level += i;
352differ:
353 i = level * 8 + __ffs(seg_a ^ seg_b);
354 return i;
355}
356
357/*
358 * Free an object after stripping the keyring flag off of the pointer.
359 */
360static void keyring_free_object(void *object)
361{
362 key_put(keyring_ptr_to_key(object));
363}
364
365/*
366 * Operations for keyring management by the index-tree routines.
367 */
368static const struct assoc_array_ops keyring_assoc_array_ops = {
369 .get_key_chunk = keyring_get_key_chunk,
370 .get_object_key_chunk = keyring_get_object_key_chunk,
371 .compare_object = keyring_compare_object,
372 .diff_objects = keyring_diff_objects,
373 .free_object = keyring_free_object,
374};
375
1da177e4 376/*
973c9f4f
DH
377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
378 * and dispose of its data.
233e4735
DH
379 *
380 * The garbage collector detects the final key_put(), removes the keyring from
381 * the serial number tree and then does RCU synchronisation before coming here,
382 * so we shouldn't need to worry about code poking around here with the RCU
383 * readlock held by this time.
1da177e4
LT
384 */
385static void keyring_destroy(struct key *keyring)
386{
1da177e4
LT
387 if (keyring->description) {
388 write_lock(&keyring_name_lock);
94efe72f 389
146aa8b1
DH
390 if (keyring->name_link.next != NULL &&
391 !list_empty(&keyring->name_link))
392 list_del(&keyring->name_link);
94efe72f 393
1da177e4
LT
394 write_unlock(&keyring_name_lock);
395 }
396
2b6aa412
MM
397 if (keyring->restrict_link) {
398 struct key_restriction *keyres = keyring->restrict_link;
399
400 key_put(keyres->key);
401 kfree(keyres);
402 }
403
b2a4df20 404 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
a8b17ed0 405}
1da177e4 406
1da177e4 407/*
973c9f4f 408 * Describe a keyring for /proc.
1da177e4
LT
409 */
410static void keyring_describe(const struct key *keyring, struct seq_file *m)
411{
c8563473 412 if (keyring->description)
1da177e4 413 seq_puts(m, keyring->description);
c8563473 414 else
1da177e4 415 seq_puts(m, "[anon]");
1da177e4 416
363b02da 417 if (key_is_positive(keyring)) {
b2a4df20
DH
418 if (keyring->keys.nr_leaves_on_tree != 0)
419 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
78b7280c
DH
420 else
421 seq_puts(m, ": empty");
78b7280c 422 }
a8b17ed0 423}
1da177e4 424
b2a4df20 425struct keyring_read_iterator_context {
e645016a 426 size_t buflen;
b2a4df20
DH
427 size_t count;
428 key_serial_t __user *buffer;
429};
430
431static int keyring_read_iterator(const void *object, void *data)
432{
433 struct keyring_read_iterator_context *ctx = data;
434 const struct key *key = keyring_ptr_to_key(object);
435 int ret;
436
437 kenter("{%s,%d},,{%zu/%zu}",
e645016a 438 key->type->name, key->serial, ctx->count, ctx->buflen);
b2a4df20 439
e645016a 440 if (ctx->count >= ctx->buflen)
b2a4df20
DH
441 return 1;
442
443 ret = put_user(key->serial, ctx->buffer);
444 if (ret < 0)
445 return ret;
446 ctx->buffer++;
447 ctx->count += sizeof(key->serial);
448 return 0;
449}
450
1da177e4 451/*
973c9f4f
DH
452 * Read a list of key IDs from the keyring's contents in binary form
453 *
b2a4df20
DH
454 * The keyring's semaphore is read-locked by the caller. This prevents someone
455 * from modifying it under us - which could cause us to read key IDs multiple
456 * times.
1da177e4
LT
457 */
458static long keyring_read(const struct key *keyring,
459 char __user *buffer, size_t buflen)
460{
b2a4df20 461 struct keyring_read_iterator_context ctx;
3239b6f2 462 long ret;
1da177e4 463
b2a4df20
DH
464 kenter("{%d},,%zu", key_serial(keyring), buflen);
465
466 if (buflen & (sizeof(key_serial_t) - 1))
467 return -EINVAL;
468
3239b6f2
EB
469 /* Copy as many key IDs as fit into the buffer */
470 if (buffer && buflen) {
471 ctx.buffer = (key_serial_t __user *)buffer;
472 ctx.buflen = buflen;
473 ctx.count = 0;
474 ret = assoc_array_iterate(&keyring->keys,
475 keyring_read_iterator, &ctx);
476 if (ret < 0) {
477 kleave(" = %ld [iterate]", ret);
478 return ret;
479 }
1da177e4
LT
480 }
481
3239b6f2
EB
482 /* Return the size of the buffer needed */
483 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
484 if (ret <= buflen)
485 kleave("= %ld [ok]", ret);
486 else
487 kleave("= %ld [buffer too small]", ret);
488 return ret;
a8b17ed0 489}
1da177e4 490
1da177e4 491/*
973c9f4f 492 * Allocate a keyring and link into the destination keyring.
1da177e4 493 */
9a56c2db 494struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
96b5c8fe 495 const struct cred *cred, key_perm_t perm,
5ac7eace 496 unsigned long flags,
2b6aa412 497 struct key_restriction *restrict_link,
5ac7eace 498 struct key *dest)
1da177e4
LT
499{
500 struct key *keyring;
501 int ret;
502
503 keyring = key_alloc(&key_type_keyring, description,
5ac7eace 504 uid, gid, cred, perm, flags, restrict_link);
1da177e4 505 if (!IS_ERR(keyring)) {
3e30148c 506 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
1da177e4
LT
507 if (ret < 0) {
508 key_put(keyring);
509 keyring = ERR_PTR(ret);
510 }
511 }
512
513 return keyring;
a8b17ed0 514}
f8aa23a5 515EXPORT_SYMBOL(keyring_alloc);
1da177e4 516
5ac7eace
DH
517/**
518 * restrict_link_reject - Give -EPERM to restrict link
519 * @keyring: The keyring being added to.
520 * @type: The type of key being added.
5ac7eace 521 * @payload: The payload of the key intended to be added.
aaf66c88 522 * @data: Additional data for evaluating restriction.
5ac7eace
DH
523 *
524 * Reject the addition of any links to a keyring. It can be overridden by
525 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
526 * adding a key to a keyring.
527 *
2b6aa412
MM
528 * This is meant to be stored in a key_restriction structure which is passed
529 * in the restrict_link parameter to keyring_alloc().
5ac7eace
DH
530 */
531int restrict_link_reject(struct key *keyring,
532 const struct key_type *type,
aaf66c88
MM
533 const union key_payload *payload,
534 struct key *restriction_key)
5ac7eace
DH
535{
536 return -EPERM;
537}
538
c06cfb08
DH
539/*
540 * By default, we keys found by getting an exact match on their descriptions.
541 */
0c903ab6
DH
542bool key_default_cmp(const struct key *key,
543 const struct key_match_data *match_data)
c06cfb08
DH
544{
545 return strcmp(key->description, match_data->raw_data) == 0;
546}
547
b2a4df20
DH
548/*
549 * Iteration function to consider each key found.
1da177e4 550 */
b2a4df20 551static int keyring_search_iterator(const void *object, void *iterator_data)
1da177e4 552{
b2a4df20
DH
553 struct keyring_search_context *ctx = iterator_data;
554 const struct key *key = keyring_ptr_to_key(object);
363b02da
DH
555 unsigned long kflags = READ_ONCE(key->flags);
556 short state = READ_ONCE(key->state);
1da177e4 557
b2a4df20 558 kenter("{%d}", key->serial);
1da177e4 559
b2a4df20
DH
560 /* ignore keys not of this type */
561 if (key->type != ctx->index_key.type) {
562 kleave(" = 0 [!type]");
563 return 0;
29db9190 564 }
1da177e4 565
b2a4df20
DH
566 /* skip invalidated, revoked and expired keys */
567 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
074d5898 568 time64_t expiry = READ_ONCE(key->expiry);
9d6c8711 569
b2a4df20
DH
570 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
571 (1 << KEY_FLAG_REVOKED))) {
572 ctx->result = ERR_PTR(-EKEYREVOKED);
573 kleave(" = %d [invrev]", ctx->skipped_ret);
574 goto skipped;
575 }
1da177e4 576
074d5898 577 if (expiry && ctx->now >= expiry) {
0b0a8415
DH
578 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
579 ctx->result = ERR_PTR(-EKEYEXPIRED);
b2a4df20
DH
580 kleave(" = %d [expire]", ctx->skipped_ret);
581 goto skipped;
582 }
583 }
664cceb0 584
b2a4df20 585 /* keys that don't match */
46291959 586 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
b2a4df20
DH
587 kleave(" = 0 [!match]");
588 return 0;
589 }
dceba994 590
b2a4df20
DH
591 /* key must have search permissions */
592 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
593 key_task_permission(make_key_ref(key, ctx->possessed),
f5895943 594 ctx->cred, KEY_NEED_SEARCH) < 0) {
b2a4df20
DH
595 ctx->result = ERR_PTR(-EACCES);
596 kleave(" = %d [!perm]", ctx->skipped_ret);
597 goto skipped;
dceba994
KC
598 }
599
b2a4df20
DH
600 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
601 /* we set a different error code if we pass a negative key */
363b02da
DH
602 if (state < 0) {
603 ctx->result = ERR_PTR(state);
b2a4df20
DH
604 kleave(" = %d [neg]", ctx->skipped_ret);
605 goto skipped;
606 }
607 }
1da177e4 608
b2a4df20
DH
609 /* Found */
610 ctx->result = make_key_ref(key, ctx->possessed);
611 kleave(" = 1 [found]");
612 return 1;
1da177e4 613
b2a4df20
DH
614skipped:
615 return ctx->skipped_ret;
616}
1da177e4 617
b2a4df20
DH
618/*
619 * Search inside a keyring for a key. We can search by walking to it
620 * directly based on its index-key or we can iterate over the entire
621 * tree looking for it, based on the match function.
622 */
623static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
624{
46291959 625 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
b2a4df20
DH
626 const void *object;
627
628 object = assoc_array_find(&keyring->keys,
629 &keyring_assoc_array_ops,
630 &ctx->index_key);
631 return object ? ctx->iterator(object, ctx) : 0;
632 }
633 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
634}
1da177e4 635
b2a4df20
DH
636/*
637 * Search a tree of keyrings that point to other keyrings up to the maximum
638 * depth.
639 */
640static bool search_nested_keyrings(struct key *keyring,
641 struct keyring_search_context *ctx)
642{
643 struct {
644 struct key *keyring;
645 struct assoc_array_node *node;
646 int slot;
647 } stack[KEYRING_SEARCH_MAX_DEPTH];
1da177e4 648
b2a4df20
DH
649 struct assoc_array_shortcut *shortcut;
650 struct assoc_array_node *node;
651 struct assoc_array_ptr *ptr;
652 struct key *key;
653 int sp = 0, slot;
1da177e4 654
b2a4df20
DH
655 kenter("{%d},{%s,%s}",
656 keyring->serial,
657 ctx->index_key.type->name,
658 ctx->index_key.description);
1da177e4 659
054f6180
DH
660#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
661 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
662 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
663
b2a4df20
DH
664 if (ctx->index_key.description)
665 ctx->index_key.desc_len = strlen(ctx->index_key.description);
1da177e4 666
b2a4df20
DH
667 /* Check to see if this top-level keyring is what we are looking for
668 * and whether it is valid or not.
669 */
46291959 670 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
b2a4df20
DH
671 keyring_compare_object(keyring, &ctx->index_key)) {
672 ctx->skipped_ret = 2;
b2a4df20
DH
673 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
674 case 1:
78b7280c 675 goto found;
b2a4df20
DH
676 case 2:
677 return false;
678 default:
679 break;
1da177e4 680 }
b2a4df20 681 }
1da177e4 682
b2a4df20 683 ctx->skipped_ret = 0;
b2a4df20
DH
684
685 /* Start processing a new keyring */
686descend_to_keyring:
687 kdebug("descend to %d", keyring->serial);
688 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
689 (1 << KEY_FLAG_REVOKED)))
690 goto not_this_keyring;
691
692 /* Search through the keys in this keyring before its searching its
693 * subtrees.
694 */
695 if (search_keyring(keyring, ctx))
1da177e4 696 goto found;
1da177e4 697
b2a4df20
DH
698 /* Then manually iterate through the keyrings nested in this one.
699 *
700 * Start from the root node of the index tree. Because of the way the
701 * hash function has been set up, keyrings cluster on the leftmost
702 * branch of the root node (root slot 0) or in the root node itself.
703 * Non-keyrings avoid the leftmost branch of the root entirely (root
704 * slots 1-15).
705 */
381f20fc 706 ptr = READ_ONCE(keyring->keys.root);
b2a4df20
DH
707 if (!ptr)
708 goto not_this_keyring;
1da177e4 709
b2a4df20
DH
710 if (assoc_array_ptr_is_shortcut(ptr)) {
711 /* If the root is a shortcut, either the keyring only contains
712 * keyring pointers (everything clusters behind root slot 0) or
713 * doesn't contain any keyring pointers.
1da177e4 714 */
b2a4df20
DH
715 shortcut = assoc_array_ptr_to_shortcut(ptr);
716 smp_read_barrier_depends();
717 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
718 goto not_this_keyring;
719
381f20fc 720 ptr = READ_ONCE(shortcut->next_node);
b2a4df20
DH
721 node = assoc_array_ptr_to_node(ptr);
722 goto begin_node;
723 }
724
725 node = assoc_array_ptr_to_node(ptr);
726 smp_read_barrier_depends();
727
728 ptr = node->slots[0];
729 if (!assoc_array_ptr_is_meta(ptr))
730 goto begin_node;
731
732descend_to_node:
733 /* Descend to a more distal node in this keyring's content tree and go
734 * through that.
735 */
736 kdebug("descend");
737 if (assoc_array_ptr_is_shortcut(ptr)) {
738 shortcut = assoc_array_ptr_to_shortcut(ptr);
739 smp_read_barrier_depends();
381f20fc 740 ptr = READ_ONCE(shortcut->next_node);
b2a4df20 741 BUG_ON(!assoc_array_ptr_is_node(ptr));
b2a4df20 742 }
9c5e45df 743 node = assoc_array_ptr_to_node(ptr);
b2a4df20
DH
744
745begin_node:
746 kdebug("begin_node");
747 smp_read_barrier_depends();
748 slot = 0;
749ascend_to_node:
750 /* Go through the slots in a node */
751 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
381f20fc 752 ptr = READ_ONCE(node->slots[slot]);
b2a4df20
DH
753
754 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
755 goto descend_to_node;
756
757 if (!keyring_ptr_is_keyring(ptr))
76d8aeab 758 continue;
1da177e4 759
b2a4df20
DH
760 key = keyring_ptr_to_key(ptr);
761
762 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
763 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
764 ctx->result = ERR_PTR(-ELOOP);
765 return false;
766 }
767 goto not_this_keyring;
768 }
769
770 /* Search a nested keyring */
771 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
772 key_task_permission(make_key_ref(key, ctx->possessed),
f5895943 773 ctx->cred, KEY_NEED_SEARCH) < 0)
76d8aeab 774 continue;
1da177e4
LT
775
776 /* stack the current position */
31d5a79d 777 stack[sp].keyring = keyring;
b2a4df20
DH
778 stack[sp].node = node;
779 stack[sp].slot = slot;
1da177e4
LT
780 sp++;
781
782 /* begin again with the new keyring */
783 keyring = key;
b2a4df20
DH
784 goto descend_to_keyring;
785 }
786
787 /* We've dealt with all the slots in the current node, so now we need
788 * to ascend to the parent and continue processing there.
789 */
381f20fc 790 ptr = READ_ONCE(node->back_pointer);
b2a4df20
DH
791 slot = node->parent_slot;
792
793 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
794 shortcut = assoc_array_ptr_to_shortcut(ptr);
795 smp_read_barrier_depends();
381f20fc 796 ptr = READ_ONCE(shortcut->back_pointer);
b2a4df20
DH
797 slot = shortcut->parent_slot;
798 }
799 if (!ptr)
800 goto not_this_keyring;
801 node = assoc_array_ptr_to_node(ptr);
802 smp_read_barrier_depends();
803 slot++;
804
805 /* If we've ascended to the root (zero backpointer), we must have just
806 * finished processing the leftmost branch rather than the root slots -
807 * so there can't be any more keyrings for us to find.
808 */
809 if (node->back_pointer) {
810 kdebug("ascend %d", slot);
811 goto ascend_to_node;
1da177e4
LT
812 }
813
b2a4df20
DH
814 /* The keyring we're looking at was disqualified or didn't contain a
815 * matching key.
816 */
664cceb0 817not_this_keyring:
b2a4df20
DH
818 kdebug("not_this_keyring %d", sp);
819 if (sp <= 0) {
820 kleave(" = false");
821 return false;
1da177e4
LT
822 }
823
b2a4df20
DH
824 /* Resume the processing of a keyring higher up in the tree */
825 sp--;
826 keyring = stack[sp].keyring;
827 node = stack[sp].node;
828 slot = stack[sp].slot + 1;
829 kdebug("ascend to %d [%d]", keyring->serial, slot);
830 goto ascend_to_node;
1da177e4 831
b2a4df20 832 /* We found a viable match */
664cceb0 833found:
b2a4df20 834 key = key_ref_to_ptr(ctx->result);
1da177e4 835 key_check(key);
b2a4df20 836 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
074d5898
BW
837 key->last_used_at = ctx->now;
838 keyring->last_used_at = ctx->now;
b2a4df20 839 while (sp > 0)
074d5898 840 stack[--sp].keyring->last_used_at = ctx->now;
b2a4df20
DH
841 }
842 kleave(" = true");
843 return true;
844}
845
846/**
847 * keyring_search_aux - Search a keyring tree for a key matching some criteria
848 * @keyring_ref: A pointer to the keyring with possession indicator.
849 * @ctx: The keyring search context.
850 *
851 * Search the supplied keyring tree for a key that matches the criteria given.
852 * The root keyring and any linked keyrings must grant Search permission to the
853 * caller to be searchable and keys can only be found if they too grant Search
854 * to the caller. The possession flag on the root keyring pointer controls use
855 * of the possessor bits in permissions checking of the entire tree. In
856 * addition, the LSM gets to forbid keyring searches and key matches.
857 *
858 * The search is performed as a breadth-then-depth search up to the prescribed
859 * limit (KEYRING_SEARCH_MAX_DEPTH).
860 *
861 * Keys are matched to the type provided and are then filtered by the match
862 * function, which is given the description to use in any way it sees fit. The
863 * match function may use any attributes of a key that it wishes to to
864 * determine the match. Normally the match function from the key type would be
865 * used.
866 *
867 * RCU can be used to prevent the keyring key lists from disappearing without
868 * the need to take lots of locks.
869 *
870 * Returns a pointer to the found key and increments the key usage count if
871 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
872 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
873 * specified keyring wasn't a keyring.
874 *
875 * In the case of a successful return, the possession attribute from
876 * @keyring_ref is propagated to the returned key reference.
877 */
878key_ref_t keyring_search_aux(key_ref_t keyring_ref,
879 struct keyring_search_context *ctx)
880{
881 struct key *keyring;
882 long err;
883
884 ctx->iterator = keyring_search_iterator;
885 ctx->possessed = is_key_possessed(keyring_ref);
886 ctx->result = ERR_PTR(-EAGAIN);
887
888 keyring = key_ref_to_ptr(keyring_ref);
889 key_check(keyring);
890
891 if (keyring->type != &key_type_keyring)
892 return ERR_PTR(-ENOTDIR);
893
894 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
f5895943 895 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
b2a4df20
DH
896 if (err < 0)
897 return ERR_PTR(err);
898 }
899
900 rcu_read_lock();
074d5898 901 ctx->now = ktime_get_real_seconds();
b2a4df20
DH
902 if (search_nested_keyrings(keyring, ctx))
903 __key_get(key_ref_to_ptr(ctx->result));
76d8aeab 904 rcu_read_unlock();
b2a4df20 905 return ctx->result;
a8b17ed0 906}
1da177e4 907
973c9f4f
DH
908/**
909 * keyring_search - Search the supplied keyring tree for a matching key
910 * @keyring: The root of the keyring tree to be searched.
911 * @type: The type of keyring we want to find.
912 * @description: The name of the keyring we want to find.
913 *
914 * As keyring_search_aux() above, but using the current task's credentials and
b2a4df20 915 * type's default matching function and preferred search method.
1da177e4 916 */
664cceb0
DH
917key_ref_t keyring_search(key_ref_t keyring,
918 struct key_type *type,
919 const char *description)
1da177e4 920{
4bdf0bc3
DH
921 struct keyring_search_context ctx = {
922 .index_key.type = type,
923 .index_key.description = description,
924 .cred = current_cred(),
c06cfb08 925 .match_data.cmp = key_default_cmp,
46291959
DH
926 .match_data.raw_data = description,
927 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
928 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
4bdf0bc3 929 };
46291959
DH
930 key_ref_t key;
931 int ret;
4bdf0bc3 932
46291959
DH
933 if (type->match_preparse) {
934 ret = type->match_preparse(&ctx.match_data);
935 if (ret < 0)
936 return ERR_PTR(ret);
937 }
938
939 key = keyring_search_aux(keyring, &ctx);
940
941 if (type->match_free)
942 type->match_free(&ctx.match_data);
943 return key;
a8b17ed0 944}
1da177e4
LT
945EXPORT_SYMBOL(keyring_search);
946
6563c91f
MM
947static struct key_restriction *keyring_restriction_alloc(
948 key_restrict_link_func_t check)
949{
950 struct key_restriction *keyres =
951 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
952
953 if (!keyres)
954 return ERR_PTR(-ENOMEM);
955
956 keyres->check = check;
957
958 return keyres;
959}
960
961/*
962 * Semaphore to serialise restriction setup to prevent reference count
963 * cycles through restriction key pointers.
964 */
965static DECLARE_RWSEM(keyring_serialise_restrict_sem);
966
967/*
968 * Check for restriction cycles that would prevent keyring garbage collection.
969 * keyring_serialise_restrict_sem must be held.
970 */
971static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
972 struct key_restriction *keyres)
973{
974 while (keyres && keyres->key &&
975 keyres->key->type == &key_type_keyring) {
976 if (keyres->key == dest_keyring)
977 return true;
978
979 keyres = keyres->key->restrict_link;
980 }
981
982 return false;
983}
984
985/**
986 * keyring_restrict - Look up and apply a restriction to a keyring
987 *
988 * @keyring: The keyring to be restricted
989 * @restriction: The restriction options to apply to the keyring
990 */
991int keyring_restrict(key_ref_t keyring_ref, const char *type,
992 const char *restriction)
993{
994 struct key *keyring;
995 struct key_type *restrict_type = NULL;
996 struct key_restriction *restrict_link;
997 int ret = 0;
998
999 keyring = key_ref_to_ptr(keyring_ref);
1000 key_check(keyring);
1001
1002 if (keyring->type != &key_type_keyring)
1003 return -ENOTDIR;
1004
1005 if (!type) {
1006 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1007 } else {
1008 restrict_type = key_type_lookup(type);
1009
1010 if (IS_ERR(restrict_type))
1011 return PTR_ERR(restrict_type);
1012
1013 if (!restrict_type->lookup_restriction) {
1014 ret = -ENOENT;
1015 goto error;
1016 }
1017
1018 restrict_link = restrict_type->lookup_restriction(restriction);
1019 }
1020
1021 if (IS_ERR(restrict_link)) {
1022 ret = PTR_ERR(restrict_link);
1023 goto error;
1024 }
1025
1026 down_write(&keyring->sem);
1027 down_write(&keyring_serialise_restrict_sem);
1028
1029 if (keyring->restrict_link)
1030 ret = -EEXIST;
1031 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1032 ret = -EDEADLK;
1033 else
1034 keyring->restrict_link = restrict_link;
1035
1036 up_write(&keyring_serialise_restrict_sem);
1037 up_write(&keyring->sem);
1038
1039 if (ret < 0) {
1040 key_put(restrict_link->key);
1041 kfree(restrict_link);
1042 }
1043
1044error:
1045 if (restrict_type)
1046 key_type_put(restrict_type);
1047
1048 return ret;
1049}
1050EXPORT_SYMBOL(keyring_restrict);
1051
1da177e4 1052/*
b2a4df20 1053 * Search the given keyring for a key that might be updated.
973c9f4f
DH
1054 *
1055 * The caller must guarantee that the keyring is a keyring and that the
b2a4df20
DH
1056 * permission is granted to modify the keyring as no check is made here. The
1057 * caller must also hold a lock on the keyring semaphore.
973c9f4f
DH
1058 *
1059 * Returns a pointer to the found key with usage count incremented if
b2a4df20
DH
1060 * successful and returns NULL if not found. Revoked and invalidated keys are
1061 * skipped over.
973c9f4f
DH
1062 *
1063 * If successful, the possession indicator is propagated from the keyring ref
1064 * to the returned key reference.
1da177e4 1065 */
b2a4df20
DH
1066key_ref_t find_key_to_update(key_ref_t keyring_ref,
1067 const struct keyring_index_key *index_key)
1da177e4 1068{
664cceb0 1069 struct key *keyring, *key;
b2a4df20 1070 const void *object;
1da177e4 1071
664cceb0 1072 keyring = key_ref_to_ptr(keyring_ref);
664cceb0 1073
b2a4df20
DH
1074 kenter("{%d},{%s,%s}",
1075 keyring->serial, index_key->type->name, index_key->description);
76d8aeab 1076
b2a4df20
DH
1077 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1078 index_key);
1da177e4 1079
b2a4df20
DH
1080 if (object)
1081 goto found;
1082
1083 kleave(" = NULL");
1084 return NULL;
1da177e4 1085
c5b60b5e 1086found:
b2a4df20
DH
1087 key = keyring_ptr_to_key(object);
1088 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1089 (1 << KEY_FLAG_REVOKED))) {
1090 kleave(" = NULL [x]");
1091 return NULL;
1092 }
ccc3e6d9 1093 __key_get(key);
b2a4df20
DH
1094 kleave(" = {%d}", key->serial);
1095 return make_key_ref(key, is_key_possessed(keyring_ref));
a8b17ed0 1096}
1da177e4 1097
1da177e4 1098/*
973c9f4f
DH
1099 * Find a keyring with the specified name.
1100 *
237bbd29
EB
1101 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1102 * user in the current user namespace are considered. If @uid_keyring is %true,
1103 * the keyring additionally must have been allocated as a user or user session
1104 * keyring; otherwise, it must grant Search permission directly to the caller.
973c9f4f
DH
1105 *
1106 * Returns a pointer to the keyring with the keyring's refcount having being
1107 * incremented on success. -ENOKEY is returned if a key could not be found.
1da177e4 1108 */
237bbd29 1109struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1da177e4
LT
1110{
1111 struct key *keyring;
1112 int bucket;
1113
1da177e4 1114 if (!name)
cea7daa3 1115 return ERR_PTR(-EINVAL);
1da177e4
LT
1116
1117 bucket = keyring_hash(name);
1118
1119 read_lock(&keyring_name_lock);
1120
1121 if (keyring_name_hash[bucket].next) {
1122 /* search this hash bucket for a keyring with a matching name
1123 * that's readable and that hasn't been revoked */
1124 list_for_each_entry(keyring,
1125 &keyring_name_hash[bucket],
146aa8b1 1126 name_link
1da177e4 1127 ) {
9a56c2db 1128 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
2ea190d0
SH
1129 continue;
1130
76d8aeab 1131 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1da177e4
LT
1132 continue;
1133
1134 if (strcmp(keyring->description, name) != 0)
1135 continue;
1136
237bbd29
EB
1137 if (uid_keyring) {
1138 if (!test_bit(KEY_FLAG_UID_KEYRING,
1139 &keyring->flags))
1140 continue;
1141 } else {
1142 if (key_permission(make_key_ref(keyring, 0),
1143 KEY_NEED_SEARCH) < 0)
1144 continue;
1145 }
1da177e4 1146
cea7daa3
TO
1147 /* we've got a match but we might end up racing with
1148 * key_cleanup() if the keyring is currently 'dead'
1149 * (ie. it has a zero usage count) */
fff29291 1150 if (!refcount_inc_not_zero(&keyring->usage))
cea7daa3 1151 continue;
074d5898 1152 keyring->last_used_at = ktime_get_real_seconds();
cea7daa3 1153 goto out;
1da177e4
LT
1154 }
1155 }
1156
1da177e4 1157 keyring = ERR_PTR(-ENOKEY);
cea7daa3
TO
1158out:
1159 read_unlock(&keyring_name_lock);
1da177e4 1160 return keyring;
a8b17ed0 1161}
1da177e4 1162
b2a4df20
DH
1163static int keyring_detect_cycle_iterator(const void *object,
1164 void *iterator_data)
1165{
1166 struct keyring_search_context *ctx = iterator_data;
1167 const struct key *key = keyring_ptr_to_key(object);
1168
1169 kenter("{%d}", key->serial);
1170
979e0d74
DH
1171 /* We might get a keyring with matching index-key that is nonetheless a
1172 * different keyring. */
46291959 1173 if (key != ctx->match_data.raw_data)
979e0d74
DH
1174 return 0;
1175
b2a4df20
DH
1176 ctx->result = ERR_PTR(-EDEADLK);
1177 return 1;
1178}
1179
1da177e4 1180/*
973c9f4f
DH
1181 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1182 * tree A at the topmost level (ie: as a direct child of A).
1183 *
1184 * Since we are adding B to A at the top level, checking for cycles should just
1185 * be a matter of seeing if node A is somewhere in tree B.
1da177e4
LT
1186 */
1187static int keyring_detect_cycle(struct key *A, struct key *B)
1188{
b2a4df20 1189 struct keyring_search_context ctx = {
46291959
DH
1190 .index_key = A->index_key,
1191 .match_data.raw_data = A,
1192 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1193 .iterator = keyring_detect_cycle_iterator,
1194 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1195 KEYRING_SEARCH_NO_UPDATE_TIME |
1196 KEYRING_SEARCH_NO_CHECK_PERM |
1197 KEYRING_SEARCH_DETECT_TOO_DEEP),
b2a4df20 1198 };
1da177e4 1199
76d8aeab 1200 rcu_read_lock();
b2a4df20 1201 search_nested_keyrings(B, &ctx);
76d8aeab 1202 rcu_read_unlock();
b2a4df20 1203 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
f70e2e06 1204}
cab8eb59 1205
1da177e4 1206/*
973c9f4f 1207 * Preallocate memory so that a key can be linked into to a keyring.
1da177e4 1208 */
b2a4df20
DH
1209int __key_link_begin(struct key *keyring,
1210 const struct keyring_index_key *index_key,
1211 struct assoc_array_edit **_edit)
f70e2e06 1212 __acquires(&keyring->sem)
423b9788 1213 __acquires(&keyring_serialise_link_sem)
1da177e4 1214{
b2a4df20
DH
1215 struct assoc_array_edit *edit;
1216 int ret;
1da177e4 1217
16feef43 1218 kenter("%d,%s,%s,",
b2a4df20
DH
1219 keyring->serial, index_key->type->name, index_key->description);
1220
1221 BUG_ON(index_key->desc_len == 0);
1da177e4 1222
1da177e4 1223 if (keyring->type != &key_type_keyring)
f70e2e06
DH
1224 return -ENOTDIR;
1225
1226 down_write(&keyring->sem);
1227
1228 ret = -EKEYREVOKED;
1229 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1230 goto error_krsem;
1da177e4 1231
f70e2e06
DH
1232 /* serialise link/link calls to prevent parallel calls causing a cycle
1233 * when linking two keyring in opposite orders */
16feef43 1234 if (index_key->type == &key_type_keyring)
553d603c
DH
1235 down_write(&keyring_serialise_link_sem);
1236
b2a4df20
DH
1237 /* Create an edit script that will insert/replace the key in the
1238 * keyring tree.
1239 */
1240 edit = assoc_array_insert(&keyring->keys,
1241 &keyring_assoc_array_ops,
1242 index_key,
1243 NULL);
1244 if (IS_ERR(edit)) {
1245 ret = PTR_ERR(edit);
034faeb9
DH
1246 goto error_sem;
1247 }
1248
1249 /* If we're not replacing a link in-place then we're going to need some
1250 * extra quota.
1251 */
1252 if (!edit->dead_leaf) {
1253 ret = key_payload_reserve(keyring,
1254 keyring->datalen + KEYQUOTA_LINK_BYTES);
1255 if (ret < 0)
1256 goto error_cancel;
1da177e4
LT
1257 }
1258
b2a4df20 1259 *_edit = edit;
f70e2e06
DH
1260 kleave(" = 0");
1261 return 0;
1da177e4 1262
034faeb9
DH
1263error_cancel:
1264 assoc_array_cancel_edit(edit);
f70e2e06 1265error_sem:
16feef43 1266 if (index_key->type == &key_type_keyring)
f70e2e06
DH
1267 up_write(&keyring_serialise_link_sem);
1268error_krsem:
1269 up_write(&keyring->sem);
1270 kleave(" = %d", ret);
1271 return ret;
1272}
1da177e4 1273
f70e2e06 1274/*
973c9f4f
DH
1275 * Check already instantiated keys aren't going to be a problem.
1276 *
1277 * The caller must have called __key_link_begin(). Don't need to call this for
1278 * keys that were created since __key_link_begin() was called.
f70e2e06
DH
1279 */
1280int __key_link_check_live_key(struct key *keyring, struct key *key)
1281{
1282 if (key->type == &key_type_keyring)
1283 /* check that we aren't going to create a cycle by linking one
1284 * keyring to another */
1285 return keyring_detect_cycle(keyring, key);
1286 return 0;
1287}
1288
1289/*
973c9f4f
DH
1290 * Link a key into to a keyring.
1291 *
1292 * Must be called with __key_link_begin() having being called. Discards any
1293 * already extant link to matching key if there is one, so that each keyring
1294 * holds at most one link to any given key of a particular type+description
1295 * combination.
f70e2e06 1296 */
b2a4df20 1297void __key_link(struct key *key, struct assoc_array_edit **_edit)
f70e2e06 1298{
ccc3e6d9 1299 __key_get(key);
b2a4df20
DH
1300 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1301 assoc_array_apply_edit(*_edit);
1302 *_edit = NULL;
f70e2e06
DH
1303}
1304
1305/*
973c9f4f
DH
1306 * Finish linking a key into to a keyring.
1307 *
1308 * Must be called with __key_link_begin() having being called.
f70e2e06 1309 */
16feef43
DH
1310void __key_link_end(struct key *keyring,
1311 const struct keyring_index_key *index_key,
b2a4df20 1312 struct assoc_array_edit *edit)
f70e2e06 1313 __releases(&keyring->sem)
423b9788 1314 __releases(&keyring_serialise_link_sem)
f70e2e06 1315{
16feef43 1316 BUG_ON(index_key->type == NULL);
b2a4df20 1317 kenter("%d,%s,", keyring->serial, index_key->type->name);
f70e2e06 1318
16feef43 1319 if (index_key->type == &key_type_keyring)
f70e2e06
DH
1320 up_write(&keyring_serialise_link_sem);
1321
ca4da5dd
CIK
1322 if (edit) {
1323 if (!edit->dead_leaf) {
1324 key_payload_reserve(keyring,
1325 keyring->datalen - KEYQUOTA_LINK_BYTES);
1326 }
b2a4df20 1327 assoc_array_cancel_edit(edit);
f70e2e06
DH
1328 }
1329 up_write(&keyring->sem);
1330}
1da177e4 1331
5ac7eace
DH
1332/*
1333 * Check addition of keys to restricted keyrings.
1334 */
1335static int __key_link_check_restriction(struct key *keyring, struct key *key)
1336{
2b6aa412 1337 if (!keyring->restrict_link || !keyring->restrict_link->check)
5ac7eace 1338 return 0;
2b6aa412
MM
1339 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1340 keyring->restrict_link->key);
5ac7eace
DH
1341}
1342
973c9f4f
DH
1343/**
1344 * key_link - Link a key to a keyring
1345 * @keyring: The keyring to make the link in.
1346 * @key: The key to link to.
1347 *
1348 * Make a link in a keyring to a key, such that the keyring holds a reference
1349 * on that key and the key can potentially be found by searching that keyring.
1350 *
1351 * This function will write-lock the keyring's semaphore and will consume some
1352 * of the user's key data quota to hold the link.
1353 *
1354 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1355 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1356 * full, -EDQUOT if there is insufficient key data quota remaining to add
1357 * another link or -ENOMEM if there's insufficient memory.
1358 *
1359 * It is assumed that the caller has checked that it is permitted for a link to
1360 * be made (the keyring should have Write permission and the key Link
1361 * permission).
1da177e4
LT
1362 */
1363int key_link(struct key *keyring, struct key *key)
1364{
b2a4df20 1365 struct assoc_array_edit *edit;
1da177e4
LT
1366 int ret;
1367
fff29291 1368 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
b2a4df20 1369
1da177e4
LT
1370 key_check(keyring);
1371 key_check(key);
1372
b2a4df20 1373 ret = __key_link_begin(keyring, &key->index_key, &edit);
f70e2e06 1374 if (ret == 0) {
fff29291 1375 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
5ac7eace
DH
1376 ret = __key_link_check_restriction(keyring, key);
1377 if (ret == 0)
1378 ret = __key_link_check_live_key(keyring, key);
f70e2e06 1379 if (ret == 0)
b2a4df20
DH
1380 __key_link(key, &edit);
1381 __key_link_end(keyring, &key->index_key, edit);
f70e2e06 1382 }
1da177e4 1383
fff29291 1384 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1da177e4 1385 return ret;
f70e2e06 1386}
1da177e4
LT
1387EXPORT_SYMBOL(key_link);
1388
973c9f4f
DH
1389/**
1390 * key_unlink - Unlink the first link to a key from a keyring.
1391 * @keyring: The keyring to remove the link from.
1392 * @key: The key the link is to.
1393 *
1394 * Remove a link from a keyring to a key.
1395 *
1396 * This function will write-lock the keyring's semaphore.
1397 *
1398 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1399 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1400 * memory.
1401 *
1402 * It is assumed that the caller has checked that it is permitted for a link to
1403 * be removed (the keyring should have Write permission; no permissions are
1404 * required on the key).
1da177e4
LT
1405 */
1406int key_unlink(struct key *keyring, struct key *key)
1407{
b2a4df20
DH
1408 struct assoc_array_edit *edit;
1409 int ret;
1da177e4
LT
1410
1411 key_check(keyring);
1412 key_check(key);
1413
1da177e4 1414 if (keyring->type != &key_type_keyring)
b2a4df20 1415 return -ENOTDIR;
1da177e4
LT
1416
1417 down_write(&keyring->sem);
1418
b2a4df20
DH
1419 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1420 &key->index_key);
1421 if (IS_ERR(edit)) {
1422 ret = PTR_ERR(edit);
1423 goto error;
1da177e4 1424 }
1da177e4 1425 ret = -ENOENT;
b2a4df20
DH
1426 if (edit == NULL)
1427 goto error;
1da177e4 1428
b2a4df20 1429 assoc_array_apply_edit(edit);
034faeb9 1430 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1da177e4
LT
1431 ret = 0;
1432
76d8aeab 1433error:
76d8aeab 1434 up_write(&keyring->sem);
b2a4df20 1435 return ret;
a8b17ed0 1436}
1da177e4
LT
1437EXPORT_SYMBOL(key_unlink);
1438
973c9f4f
DH
1439/**
1440 * keyring_clear - Clear a keyring
1441 * @keyring: The keyring to clear.
1442 *
1443 * Clear the contents of the specified keyring.
1444 *
1445 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1da177e4
LT
1446 */
1447int keyring_clear(struct key *keyring)
1448{
b2a4df20 1449 struct assoc_array_edit *edit;
76d8aeab 1450 int ret;
1da177e4 1451
b2a4df20
DH
1452 if (keyring->type != &key_type_keyring)
1453 return -ENOTDIR;
1da177e4 1454
b2a4df20 1455 down_write(&keyring->sem);
1da177e4 1456
b2a4df20
DH
1457 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1458 if (IS_ERR(edit)) {
1459 ret = PTR_ERR(edit);
1460 } else {
1461 if (edit)
1462 assoc_array_apply_edit(edit);
1463 key_payload_reserve(keyring, 0);
1da177e4
LT
1464 ret = 0;
1465 }
1466
b2a4df20 1467 up_write(&keyring->sem);
1da177e4 1468 return ret;
a8b17ed0 1469}
1da177e4 1470EXPORT_SYMBOL(keyring_clear);
31204ed9 1471
31204ed9 1472/*
973c9f4f
DH
1473 * Dispose of the links from a revoked keyring.
1474 *
1475 * This is called with the key sem write-locked.
31204ed9
DH
1476 */
1477static void keyring_revoke(struct key *keyring)
1478{
b2a4df20 1479 struct assoc_array_edit *edit;
f0641cba 1480
b2a4df20
DH
1481 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1482 if (!IS_ERR(edit)) {
1483 if (edit)
1484 assoc_array_apply_edit(edit);
1485 key_payload_reserve(keyring, 0);
1486 }
1487}
31204ed9 1488
62fe3182 1489static bool keyring_gc_select_iterator(void *object, void *iterator_data)
b2a4df20
DH
1490{
1491 struct key *key = keyring_ptr_to_key(object);
074d5898 1492 time64_t *limit = iterator_data;
31204ed9 1493
b2a4df20
DH
1494 if (key_is_dead(key, *limit))
1495 return false;
1496 key_get(key);
1497 return true;
a8b17ed0 1498}
5d135440 1499
62fe3182
DH
1500static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1501{
1502 const struct key *key = keyring_ptr_to_key(object);
074d5898 1503 time64_t *limit = iterator_data;
62fe3182
DH
1504
1505 key_check(key);
1506 return key_is_dead(key, *limit);
1507}
1508
5d135440 1509/*
62fe3182 1510 * Garbage collect pointers from a keyring.
973c9f4f 1511 *
62fe3182
DH
1512 * Not called with any locks held. The keyring's key struct will not be
1513 * deallocated under us as only our caller may deallocate it.
5d135440 1514 */
074d5898 1515void keyring_gc(struct key *keyring, time64_t limit)
5d135440 1516{
62fe3182
DH
1517 int result;
1518
1519 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
5d135440 1520
62fe3182
DH
1521 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1522 (1 << KEY_FLAG_REVOKED)))
1523 goto dont_gc;
1524
1525 /* scan the keyring looking for dead keys */
1526 rcu_read_lock();
1527 result = assoc_array_iterate(&keyring->keys,
1528 keyring_gc_check_iterator, &limit);
1529 rcu_read_unlock();
1530 if (result == true)
1531 goto do_gc;
1532
1533dont_gc:
1534 kleave(" [no gc]");
1535 return;
1536
1537do_gc:
5d135440 1538 down_write(&keyring->sem);
b2a4df20 1539 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
62fe3182 1540 keyring_gc_select_iterator, &limit);
c08ef808 1541 up_write(&keyring->sem);
62fe3182 1542 kleave(" [gc]");
5d135440 1543}
2b6aa412
MM
1544
1545/*
1546 * Garbage collect restriction pointers from a keyring.
1547 *
1548 * Keyring restrictions are associated with a key type, and must be cleaned
1549 * up if the key type is unregistered. The restriction is altered to always
1550 * reject additional keys so a keyring cannot be opened up by unregistering
1551 * a key type.
1552 *
1553 * Not called with any keyring locks held. The keyring's key struct will not
1554 * be deallocated under us as only our caller may deallocate it.
1555 *
1556 * The caller is required to hold key_types_sem and dead_type->sem. This is
1557 * fulfilled by key_gc_keytype() holding the locks on behalf of
1558 * key_garbage_collector(), which it invokes on a workqueue.
1559 */
1560void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1561{
1562 struct key_restriction *keyres;
1563
1564 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1565
1566 /*
1567 * keyring->restrict_link is only assigned at key allocation time
1568 * or with the key type locked, so the only values that could be
1569 * concurrently assigned to keyring->restrict_link are for key
1570 * types other than dead_type. Given this, it's ok to check
1571 * the key type before acquiring keyring->sem.
1572 */
1573 if (!dead_type || !keyring->restrict_link ||
1574 keyring->restrict_link->keytype != dead_type) {
1575 kleave(" [no restriction gc]");
1576 return;
1577 }
1578
1579 /* Lock the keyring to ensure that a link is not in progress */
1580 down_write(&keyring->sem);
1581
1582 keyres = keyring->restrict_link;
1583
1584 keyres->check = restrict_link_reject;
1585
1586 key_put(keyres->key);
1587 keyres->key = NULL;
1588 keyres->keytype = NULL;
1589
1590 up_write(&keyring->sem);
1591
1592 kleave(" [restriction gc]");
1593}