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1/* Keyring handling
2 *
3 * Copyright (C) 2004-2005, 2008, 2013 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#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/security.h>
17#include <linux/seq_file.h>
18#include <linux/err.h>
19#include <keys/keyring-type.h>
20#include <keys/user-type.h>
21#include <linux/assoc_array_priv.h>
22#include <linux/uaccess.h>
23#include "internal.h"
24
25/*
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
28 */
29#define KEYRING_SEARCH_MAX_DEPTH 6
30
31/*
32 * We keep all named keyrings in a hash to speed looking them up.
33 */
34#define KEYRING_NAME_HASH_SIZE (1 << 5)
35
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
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++)
66 bucket += (unsigned char)*desc;
67
68 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
69}
70
71/*
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.
75 */
76static int keyring_preparse(struct key_preparsed_payload *prep);
77static void keyring_free_preparse(struct key_preparsed_payload *prep);
78static int keyring_instantiate(struct key *keyring,
79 struct key_preparsed_payload *prep);
80static void keyring_revoke(struct key *keyring);
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",
88 .def_datalen = 0,
89 .preparse = keyring_preparse,
90 .free_preparse = keyring_free_preparse,
91 .instantiate = keyring_instantiate,
92 .revoke = keyring_revoke,
93 .destroy = keyring_destroy,
94 .describe = keyring_describe,
95 .read = keyring_read,
96};
97EXPORT_SYMBOL(key_type_keyring);
98
99/*
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
102 */
103static DECLARE_RWSEM(keyring_serialise_link_sem);
104
105/*
106 * Publish the name of a keyring so that it can be found by name (if it has
107 * one).
108 */
109static void keyring_publish_name(struct key *keyring)
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
121 list_add_tail(&keyring->name_link,
122 &keyring_name_hash[bucket]);
123
124 write_unlock(&keyring_name_lock);
125 }
126}
127
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
143/*
144 * Initialise a keyring.
145 *
146 * Returns 0 on success, -EINVAL if given any data.
147 */
148static int keyring_instantiate(struct key *keyring,
149 struct key_preparsed_payload *prep)
150{
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;
155}
156
157/*
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;
174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
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 */
208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
211 return (hash + (hash << level_shift)) & ~fan_mask;
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.
229 */
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)
279{
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;
287}
288
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 */
293static int keyring_diff_objects(const void *object, const void *data)
294{
295 const struct key *key_a = keyring_ptr_to_key(object);
296 const struct keyring_index_key *a = &key_a->index_key;
297 const struct keyring_index_key *b = data;
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
376/*
377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
378 * and dispose of its data.
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.
384 */
385static void keyring_destroy(struct key *keyring)
386{
387 if (keyring->description) {
388 write_lock(&keyring_name_lock);
389
390 if (keyring->name_link.next != NULL &&
391 !list_empty(&keyring->name_link))
392 list_del(&keyring->name_link);
393
394 write_unlock(&keyring_name_lock);
395 }
396
397 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
398}
399
400/*
401 * Describe a keyring for /proc.
402 */
403static void keyring_describe(const struct key *keyring, struct seq_file *m)
404{
405 if (keyring->description)
406 seq_puts(m, keyring->description);
407 else
408 seq_puts(m, "[anon]");
409
410 if (key_is_instantiated(keyring)) {
411 if (keyring->keys.nr_leaves_on_tree != 0)
412 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
413 else
414 seq_puts(m, ": empty");
415 }
416}
417
418struct keyring_read_iterator_context {
419 size_t qty;
420 size_t count;
421 key_serial_t __user *buffer;
422};
423
424static int keyring_read_iterator(const void *object, void *data)
425{
426 struct keyring_read_iterator_context *ctx = data;
427 const struct key *key = keyring_ptr_to_key(object);
428 int ret;
429
430 kenter("{%s,%d},,{%zu/%zu}",
431 key->type->name, key->serial, ctx->count, ctx->qty);
432
433 if (ctx->count >= ctx->qty)
434 return 1;
435
436 ret = put_user(key->serial, ctx->buffer);
437 if (ret < 0)
438 return ret;
439 ctx->buffer++;
440 ctx->count += sizeof(key->serial);
441 return 0;
442}
443
444/*
445 * Read a list of key IDs from the keyring's contents in binary form
446 *
447 * The keyring's semaphore is read-locked by the caller. This prevents someone
448 * from modifying it under us - which could cause us to read key IDs multiple
449 * times.
450 */
451static long keyring_read(const struct key *keyring,
452 char __user *buffer, size_t buflen)
453{
454 struct keyring_read_iterator_context ctx;
455 unsigned long nr_keys;
456 int ret;
457
458 kenter("{%d},,%zu", key_serial(keyring), buflen);
459
460 if (buflen & (sizeof(key_serial_t) - 1))
461 return -EINVAL;
462
463 nr_keys = keyring->keys.nr_leaves_on_tree;
464 if (nr_keys == 0)
465 return 0;
466
467 /* Calculate how much data we could return */
468 ctx.qty = nr_keys * sizeof(key_serial_t);
469
470 if (!buffer || !buflen)
471 return ctx.qty;
472
473 if (buflen > ctx.qty)
474 ctx.qty = buflen;
475
476 /* Copy the IDs of the subscribed keys into the buffer */
477 ctx.buffer = (key_serial_t __user *)buffer;
478 ctx.count = 0;
479 ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
480 if (ret < 0) {
481 kleave(" = %d [iterate]", ret);
482 return ret;
483 }
484
485 kleave(" = %zu [ok]", ctx.count);
486 return ctx.count;
487}
488
489/*
490 * Allocate a keyring and link into the destination keyring.
491 */
492struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
493 const struct cred *cred, key_perm_t perm,
494 unsigned long flags, struct key *dest)
495{
496 struct key *keyring;
497 int ret;
498
499 keyring = key_alloc(&key_type_keyring, description,
500 uid, gid, cred, perm, flags);
501 if (!IS_ERR(keyring)) {
502 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
503 if (ret < 0) {
504 key_put(keyring);
505 keyring = ERR_PTR(ret);
506 }
507 }
508
509 return keyring;
510}
511EXPORT_SYMBOL(keyring_alloc);
512
513/*
514 * By default, we keys found by getting an exact match on their descriptions.
515 */
516bool key_default_cmp(const struct key *key,
517 const struct key_match_data *match_data)
518{
519 return strcmp(key->description, match_data->raw_data) == 0;
520}
521
522/*
523 * Iteration function to consider each key found.
524 */
525static int keyring_search_iterator(const void *object, void *iterator_data)
526{
527 struct keyring_search_context *ctx = iterator_data;
528 const struct key *key = keyring_ptr_to_key(object);
529 unsigned long kflags = key->flags;
530
531 kenter("{%d}", key->serial);
532
533 /* ignore keys not of this type */
534 if (key->type != ctx->index_key.type) {
535 kleave(" = 0 [!type]");
536 return 0;
537 }
538
539 /* skip invalidated, revoked and expired keys */
540 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
541 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
542 (1 << KEY_FLAG_REVOKED))) {
543 ctx->result = ERR_PTR(-EKEYREVOKED);
544 kleave(" = %d [invrev]", ctx->skipped_ret);
545 goto skipped;
546 }
547
548 if (key->expiry && ctx->now.tv_sec >= key->expiry) {
549 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
550 ctx->result = ERR_PTR(-EKEYEXPIRED);
551 kleave(" = %d [expire]", ctx->skipped_ret);
552 goto skipped;
553 }
554 }
555
556 /* keys that don't match */
557 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
558 kleave(" = 0 [!match]");
559 return 0;
560 }
561
562 /* key must have search permissions */
563 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
564 key_task_permission(make_key_ref(key, ctx->possessed),
565 ctx->cred, KEY_NEED_SEARCH) < 0) {
566 ctx->result = ERR_PTR(-EACCES);
567 kleave(" = %d [!perm]", ctx->skipped_ret);
568 goto skipped;
569 }
570
571 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
572 /* we set a different error code if we pass a negative key */
573 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
574 smp_rmb();
575 ctx->result = ERR_PTR(key->reject_error);
576 kleave(" = %d [neg]", ctx->skipped_ret);
577 goto skipped;
578 }
579 }
580
581 /* Found */
582 ctx->result = make_key_ref(key, ctx->possessed);
583 kleave(" = 1 [found]");
584 return 1;
585
586skipped:
587 return ctx->skipped_ret;
588}
589
590/*
591 * Search inside a keyring for a key. We can search by walking to it
592 * directly based on its index-key or we can iterate over the entire
593 * tree looking for it, based on the match function.
594 */
595static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
596{
597 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
598 const void *object;
599
600 object = assoc_array_find(&keyring->keys,
601 &keyring_assoc_array_ops,
602 &ctx->index_key);
603 return object ? ctx->iterator(object, ctx) : 0;
604 }
605 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
606}
607
608/*
609 * Search a tree of keyrings that point to other keyrings up to the maximum
610 * depth.
611 */
612static bool search_nested_keyrings(struct key *keyring,
613 struct keyring_search_context *ctx)
614{
615 struct {
616 struct key *keyring;
617 struct assoc_array_node *node;
618 int slot;
619 } stack[KEYRING_SEARCH_MAX_DEPTH];
620
621 struct assoc_array_shortcut *shortcut;
622 struct assoc_array_node *node;
623 struct assoc_array_ptr *ptr;
624 struct key *key;
625 int sp = 0, slot;
626
627 kenter("{%d},{%s,%s}",
628 keyring->serial,
629 ctx->index_key.type->name,
630 ctx->index_key.description);
631
632#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
633 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
634 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
635
636 if (ctx->index_key.description)
637 ctx->index_key.desc_len = strlen(ctx->index_key.description);
638
639 /* Check to see if this top-level keyring is what we are looking for
640 * and whether it is valid or not.
641 */
642 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
643 keyring_compare_object(keyring, &ctx->index_key)) {
644 ctx->skipped_ret = 2;
645 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
646 case 1:
647 goto found;
648 case 2:
649 return false;
650 default:
651 break;
652 }
653 }
654
655 ctx->skipped_ret = 0;
656
657 /* Start processing a new keyring */
658descend_to_keyring:
659 kdebug("descend to %d", keyring->serial);
660 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
661 (1 << KEY_FLAG_REVOKED)))
662 goto not_this_keyring;
663
664 /* Search through the keys in this keyring before its searching its
665 * subtrees.
666 */
667 if (search_keyring(keyring, ctx))
668 goto found;
669
670 /* Then manually iterate through the keyrings nested in this one.
671 *
672 * Start from the root node of the index tree. Because of the way the
673 * hash function has been set up, keyrings cluster on the leftmost
674 * branch of the root node (root slot 0) or in the root node itself.
675 * Non-keyrings avoid the leftmost branch of the root entirely (root
676 * slots 1-15).
677 */
678 ptr = ACCESS_ONCE(keyring->keys.root);
679 if (!ptr)
680 goto not_this_keyring;
681
682 if (assoc_array_ptr_is_shortcut(ptr)) {
683 /* If the root is a shortcut, either the keyring only contains
684 * keyring pointers (everything clusters behind root slot 0) or
685 * doesn't contain any keyring pointers.
686 */
687 shortcut = assoc_array_ptr_to_shortcut(ptr);
688 smp_read_barrier_depends();
689 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
690 goto not_this_keyring;
691
692 ptr = ACCESS_ONCE(shortcut->next_node);
693 node = assoc_array_ptr_to_node(ptr);
694 goto begin_node;
695 }
696
697 node = assoc_array_ptr_to_node(ptr);
698 smp_read_barrier_depends();
699
700 ptr = node->slots[0];
701 if (!assoc_array_ptr_is_meta(ptr))
702 goto begin_node;
703
704descend_to_node:
705 /* Descend to a more distal node in this keyring's content tree and go
706 * through that.
707 */
708 kdebug("descend");
709 if (assoc_array_ptr_is_shortcut(ptr)) {
710 shortcut = assoc_array_ptr_to_shortcut(ptr);
711 smp_read_barrier_depends();
712 ptr = ACCESS_ONCE(shortcut->next_node);
713 BUG_ON(!assoc_array_ptr_is_node(ptr));
714 }
715 node = assoc_array_ptr_to_node(ptr);
716
717begin_node:
718 kdebug("begin_node");
719 smp_read_barrier_depends();
720 slot = 0;
721ascend_to_node:
722 /* Go through the slots in a node */
723 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
724 ptr = ACCESS_ONCE(node->slots[slot]);
725
726 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
727 goto descend_to_node;
728
729 if (!keyring_ptr_is_keyring(ptr))
730 continue;
731
732 key = keyring_ptr_to_key(ptr);
733
734 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
735 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
736 ctx->result = ERR_PTR(-ELOOP);
737 return false;
738 }
739 goto not_this_keyring;
740 }
741
742 /* Search a nested keyring */
743 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
744 key_task_permission(make_key_ref(key, ctx->possessed),
745 ctx->cred, KEY_NEED_SEARCH) < 0)
746 continue;
747
748 /* stack the current position */
749 stack[sp].keyring = keyring;
750 stack[sp].node = node;
751 stack[sp].slot = slot;
752 sp++;
753
754 /* begin again with the new keyring */
755 keyring = key;
756 goto descend_to_keyring;
757 }
758
759 /* We've dealt with all the slots in the current node, so now we need
760 * to ascend to the parent and continue processing there.
761 */
762 ptr = ACCESS_ONCE(node->back_pointer);
763 slot = node->parent_slot;
764
765 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
766 shortcut = assoc_array_ptr_to_shortcut(ptr);
767 smp_read_barrier_depends();
768 ptr = ACCESS_ONCE(shortcut->back_pointer);
769 slot = shortcut->parent_slot;
770 }
771 if (!ptr)
772 goto not_this_keyring;
773 node = assoc_array_ptr_to_node(ptr);
774 smp_read_barrier_depends();
775 slot++;
776
777 /* If we've ascended to the root (zero backpointer), we must have just
778 * finished processing the leftmost branch rather than the root slots -
779 * so there can't be any more keyrings for us to find.
780 */
781 if (node->back_pointer) {
782 kdebug("ascend %d", slot);
783 goto ascend_to_node;
784 }
785
786 /* The keyring we're looking at was disqualified or didn't contain a
787 * matching key.
788 */
789not_this_keyring:
790 kdebug("not_this_keyring %d", sp);
791 if (sp <= 0) {
792 kleave(" = false");
793 return false;
794 }
795
796 /* Resume the processing of a keyring higher up in the tree */
797 sp--;
798 keyring = stack[sp].keyring;
799 node = stack[sp].node;
800 slot = stack[sp].slot + 1;
801 kdebug("ascend to %d [%d]", keyring->serial, slot);
802 goto ascend_to_node;
803
804 /* We found a viable match */
805found:
806 key = key_ref_to_ptr(ctx->result);
807 key_check(key);
808 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
809 key->last_used_at = ctx->now.tv_sec;
810 keyring->last_used_at = ctx->now.tv_sec;
811 while (sp > 0)
812 stack[--sp].keyring->last_used_at = ctx->now.tv_sec;
813 }
814 kleave(" = true");
815 return true;
816}
817
818/**
819 * keyring_search_aux - Search a keyring tree for a key matching some criteria
820 * @keyring_ref: A pointer to the keyring with possession indicator.
821 * @ctx: The keyring search context.
822 *
823 * Search the supplied keyring tree for a key that matches the criteria given.
824 * The root keyring and any linked keyrings must grant Search permission to the
825 * caller to be searchable and keys can only be found if they too grant Search
826 * to the caller. The possession flag on the root keyring pointer controls use
827 * of the possessor bits in permissions checking of the entire tree. In
828 * addition, the LSM gets to forbid keyring searches and key matches.
829 *
830 * The search is performed as a breadth-then-depth search up to the prescribed
831 * limit (KEYRING_SEARCH_MAX_DEPTH).
832 *
833 * Keys are matched to the type provided and are then filtered by the match
834 * function, which is given the description to use in any way it sees fit. The
835 * match function may use any attributes of a key that it wishes to to
836 * determine the match. Normally the match function from the key type would be
837 * used.
838 *
839 * RCU can be used to prevent the keyring key lists from disappearing without
840 * the need to take lots of locks.
841 *
842 * Returns a pointer to the found key and increments the key usage count if
843 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
844 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
845 * specified keyring wasn't a keyring.
846 *
847 * In the case of a successful return, the possession attribute from
848 * @keyring_ref is propagated to the returned key reference.
849 */
850key_ref_t keyring_search_aux(key_ref_t keyring_ref,
851 struct keyring_search_context *ctx)
852{
853 struct key *keyring;
854 long err;
855
856 ctx->iterator = keyring_search_iterator;
857 ctx->possessed = is_key_possessed(keyring_ref);
858 ctx->result = ERR_PTR(-EAGAIN);
859
860 keyring = key_ref_to_ptr(keyring_ref);
861 key_check(keyring);
862
863 if (keyring->type != &key_type_keyring)
864 return ERR_PTR(-ENOTDIR);
865
866 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
867 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
868 if (err < 0)
869 return ERR_PTR(err);
870 }
871
872 rcu_read_lock();
873 ctx->now = current_kernel_time();
874 if (search_nested_keyrings(keyring, ctx))
875 __key_get(key_ref_to_ptr(ctx->result));
876 rcu_read_unlock();
877 return ctx->result;
878}
879
880/**
881 * keyring_search - Search the supplied keyring tree for a matching key
882 * @keyring: The root of the keyring tree to be searched.
883 * @type: The type of keyring we want to find.
884 * @description: The name of the keyring we want to find.
885 *
886 * As keyring_search_aux() above, but using the current task's credentials and
887 * type's default matching function and preferred search method.
888 */
889key_ref_t keyring_search(key_ref_t keyring,
890 struct key_type *type,
891 const char *description)
892{
893 struct keyring_search_context ctx = {
894 .index_key.type = type,
895 .index_key.description = description,
896 .cred = current_cred(),
897 .match_data.cmp = key_default_cmp,
898 .match_data.raw_data = description,
899 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
900 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
901 };
902 key_ref_t key;
903 int ret;
904
905 if (type->match_preparse) {
906 ret = type->match_preparse(&ctx.match_data);
907 if (ret < 0)
908 return ERR_PTR(ret);
909 }
910
911 key = keyring_search_aux(keyring, &ctx);
912
913 if (type->match_free)
914 type->match_free(&ctx.match_data);
915 return key;
916}
917EXPORT_SYMBOL(keyring_search);
918
919/*
920 * Search the given keyring for a key that might be updated.
921 *
922 * The caller must guarantee that the keyring is a keyring and that the
923 * permission is granted to modify the keyring as no check is made here. The
924 * caller must also hold a lock on the keyring semaphore.
925 *
926 * Returns a pointer to the found key with usage count incremented if
927 * successful and returns NULL if not found. Revoked and invalidated keys are
928 * skipped over.
929 *
930 * If successful, the possession indicator is propagated from the keyring ref
931 * to the returned key reference.
932 */
933key_ref_t find_key_to_update(key_ref_t keyring_ref,
934 const struct keyring_index_key *index_key)
935{
936 struct key *keyring, *key;
937 const void *object;
938
939 keyring = key_ref_to_ptr(keyring_ref);
940
941 kenter("{%d},{%s,%s}",
942 keyring->serial, index_key->type->name, index_key->description);
943
944 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
945 index_key);
946
947 if (object)
948 goto found;
949
950 kleave(" = NULL");
951 return NULL;
952
953found:
954 key = keyring_ptr_to_key(object);
955 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
956 (1 << KEY_FLAG_REVOKED))) {
957 kleave(" = NULL [x]");
958 return NULL;
959 }
960 __key_get(key);
961 kleave(" = {%d}", key->serial);
962 return make_key_ref(key, is_key_possessed(keyring_ref));
963}
964
965/*
966 * Find a keyring with the specified name.
967 *
968 * All named keyrings in the current user namespace are searched, provided they
969 * grant Search permission directly to the caller (unless this check is
970 * skipped). Keyrings whose usage points have reached zero or who have been
971 * revoked are skipped.
972 *
973 * Returns a pointer to the keyring with the keyring's refcount having being
974 * incremented on success. -ENOKEY is returned if a key could not be found.
975 */
976struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
977{
978 struct key *keyring;
979 int bucket;
980
981 if (!name)
982 return ERR_PTR(-EINVAL);
983
984 bucket = keyring_hash(name);
985
986 read_lock(&keyring_name_lock);
987
988 if (keyring_name_hash[bucket].next) {
989 /* search this hash bucket for a keyring with a matching name
990 * that's readable and that hasn't been revoked */
991 list_for_each_entry(keyring,
992 &keyring_name_hash[bucket],
993 name_link
994 ) {
995 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
996 continue;
997
998 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
999 continue;
1000
1001 if (strcmp(keyring->description, name) != 0)
1002 continue;
1003
1004 if (!skip_perm_check &&
1005 key_permission(make_key_ref(keyring, 0),
1006 KEY_NEED_SEARCH) < 0)
1007 continue;
1008
1009 /* we've got a match but we might end up racing with
1010 * key_cleanup() if the keyring is currently 'dead'
1011 * (ie. it has a zero usage count) */
1012 if (!atomic_inc_not_zero(&keyring->usage))
1013 continue;
1014 keyring->last_used_at = current_kernel_time().tv_sec;
1015 goto out;
1016 }
1017 }
1018
1019 keyring = ERR_PTR(-ENOKEY);
1020out:
1021 read_unlock(&keyring_name_lock);
1022 return keyring;
1023}
1024
1025static int keyring_detect_cycle_iterator(const void *object,
1026 void *iterator_data)
1027{
1028 struct keyring_search_context *ctx = iterator_data;
1029 const struct key *key = keyring_ptr_to_key(object);
1030
1031 kenter("{%d}", key->serial);
1032
1033 /* We might get a keyring with matching index-key that is nonetheless a
1034 * different keyring. */
1035 if (key != ctx->match_data.raw_data)
1036 return 0;
1037
1038 ctx->result = ERR_PTR(-EDEADLK);
1039 return 1;
1040}
1041
1042/*
1043 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1044 * tree A at the topmost level (ie: as a direct child of A).
1045 *
1046 * Since we are adding B to A at the top level, checking for cycles should just
1047 * be a matter of seeing if node A is somewhere in tree B.
1048 */
1049static int keyring_detect_cycle(struct key *A, struct key *B)
1050{
1051 struct keyring_search_context ctx = {
1052 .index_key = A->index_key,
1053 .match_data.raw_data = A,
1054 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1055 .iterator = keyring_detect_cycle_iterator,
1056 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1057 KEYRING_SEARCH_NO_UPDATE_TIME |
1058 KEYRING_SEARCH_NO_CHECK_PERM |
1059 KEYRING_SEARCH_DETECT_TOO_DEEP),
1060 };
1061
1062 rcu_read_lock();
1063 search_nested_keyrings(B, &ctx);
1064 rcu_read_unlock();
1065 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1066}
1067
1068/*
1069 * Preallocate memory so that a key can be linked into to a keyring.
1070 */
1071int __key_link_begin(struct key *keyring,
1072 const struct keyring_index_key *index_key,
1073 struct assoc_array_edit **_edit)
1074 __acquires(&keyring->sem)
1075 __acquires(&keyring_serialise_link_sem)
1076{
1077 struct assoc_array_edit *edit;
1078 int ret;
1079
1080 kenter("%d,%s,%s,",
1081 keyring->serial, index_key->type->name, index_key->description);
1082
1083 BUG_ON(index_key->desc_len == 0);
1084
1085 if (keyring->type != &key_type_keyring)
1086 return -ENOTDIR;
1087
1088 down_write(&keyring->sem);
1089
1090 ret = -EKEYREVOKED;
1091 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1092 goto error_krsem;
1093
1094 /* serialise link/link calls to prevent parallel calls causing a cycle
1095 * when linking two keyring in opposite orders */
1096 if (index_key->type == &key_type_keyring)
1097 down_write(&keyring_serialise_link_sem);
1098
1099 /* Create an edit script that will insert/replace the key in the
1100 * keyring tree.
1101 */
1102 edit = assoc_array_insert(&keyring->keys,
1103 &keyring_assoc_array_ops,
1104 index_key,
1105 NULL);
1106 if (IS_ERR(edit)) {
1107 ret = PTR_ERR(edit);
1108 goto error_sem;
1109 }
1110
1111 /* If we're not replacing a link in-place then we're going to need some
1112 * extra quota.
1113 */
1114 if (!edit->dead_leaf) {
1115 ret = key_payload_reserve(keyring,
1116 keyring->datalen + KEYQUOTA_LINK_BYTES);
1117 if (ret < 0)
1118 goto error_cancel;
1119 }
1120
1121 *_edit = edit;
1122 kleave(" = 0");
1123 return 0;
1124
1125error_cancel:
1126 assoc_array_cancel_edit(edit);
1127error_sem:
1128 if (index_key->type == &key_type_keyring)
1129 up_write(&keyring_serialise_link_sem);
1130error_krsem:
1131 up_write(&keyring->sem);
1132 kleave(" = %d", ret);
1133 return ret;
1134}
1135
1136/*
1137 * Check already instantiated keys aren't going to be a problem.
1138 *
1139 * The caller must have called __key_link_begin(). Don't need to call this for
1140 * keys that were created since __key_link_begin() was called.
1141 */
1142int __key_link_check_live_key(struct key *keyring, struct key *key)
1143{
1144 if (key->type == &key_type_keyring)
1145 /* check that we aren't going to create a cycle by linking one
1146 * keyring to another */
1147 return keyring_detect_cycle(keyring, key);
1148 return 0;
1149}
1150
1151/*
1152 * Link a key into to a keyring.
1153 *
1154 * Must be called with __key_link_begin() having being called. Discards any
1155 * already extant link to matching key if there is one, so that each keyring
1156 * holds at most one link to any given key of a particular type+description
1157 * combination.
1158 */
1159void __key_link(struct key *key, struct assoc_array_edit **_edit)
1160{
1161 __key_get(key);
1162 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1163 assoc_array_apply_edit(*_edit);
1164 *_edit = NULL;
1165}
1166
1167/*
1168 * Finish linking a key into to a keyring.
1169 *
1170 * Must be called with __key_link_begin() having being called.
1171 */
1172void __key_link_end(struct key *keyring,
1173 const struct keyring_index_key *index_key,
1174 struct assoc_array_edit *edit)
1175 __releases(&keyring->sem)
1176 __releases(&keyring_serialise_link_sem)
1177{
1178 BUG_ON(index_key->type == NULL);
1179 kenter("%d,%s,", keyring->serial, index_key->type->name);
1180
1181 if (index_key->type == &key_type_keyring)
1182 up_write(&keyring_serialise_link_sem);
1183
1184 if (edit) {
1185 if (!edit->dead_leaf) {
1186 key_payload_reserve(keyring,
1187 keyring->datalen - KEYQUOTA_LINK_BYTES);
1188 }
1189 assoc_array_cancel_edit(edit);
1190 }
1191 up_write(&keyring->sem);
1192}
1193
1194/**
1195 * key_link - Link a key to a keyring
1196 * @keyring: The keyring to make the link in.
1197 * @key: The key to link to.
1198 *
1199 * Make a link in a keyring to a key, such that the keyring holds a reference
1200 * on that key and the key can potentially be found by searching that keyring.
1201 *
1202 * This function will write-lock the keyring's semaphore and will consume some
1203 * of the user's key data quota to hold the link.
1204 *
1205 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1206 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1207 * full, -EDQUOT if there is insufficient key data quota remaining to add
1208 * another link or -ENOMEM if there's insufficient memory.
1209 *
1210 * It is assumed that the caller has checked that it is permitted for a link to
1211 * be made (the keyring should have Write permission and the key Link
1212 * permission).
1213 */
1214int key_link(struct key *keyring, struct key *key)
1215{
1216 struct assoc_array_edit *edit;
1217 int ret;
1218
1219 kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1220
1221 key_check(keyring);
1222 key_check(key);
1223
1224 if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
1225 !test_bit(KEY_FLAG_TRUSTED, &key->flags))
1226 return -EPERM;
1227
1228 ret = __key_link_begin(keyring, &key->index_key, &edit);
1229 if (ret == 0) {
1230 kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1231 ret = __key_link_check_live_key(keyring, key);
1232 if (ret == 0)
1233 __key_link(key, &edit);
1234 __key_link_end(keyring, &key->index_key, edit);
1235 }
1236
1237 kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
1238 return ret;
1239}
1240EXPORT_SYMBOL(key_link);
1241
1242/**
1243 * key_unlink - Unlink the first link to a key from a keyring.
1244 * @keyring: The keyring to remove the link from.
1245 * @key: The key the link is to.
1246 *
1247 * Remove a link from a keyring to a key.
1248 *
1249 * This function will write-lock the keyring's semaphore.
1250 *
1251 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1252 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1253 * memory.
1254 *
1255 * It is assumed that the caller has checked that it is permitted for a link to
1256 * be removed (the keyring should have Write permission; no permissions are
1257 * required on the key).
1258 */
1259int key_unlink(struct key *keyring, struct key *key)
1260{
1261 struct assoc_array_edit *edit;
1262 int ret;
1263
1264 key_check(keyring);
1265 key_check(key);
1266
1267 if (keyring->type != &key_type_keyring)
1268 return -ENOTDIR;
1269
1270 down_write(&keyring->sem);
1271
1272 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1273 &key->index_key);
1274 if (IS_ERR(edit)) {
1275 ret = PTR_ERR(edit);
1276 goto error;
1277 }
1278 ret = -ENOENT;
1279 if (edit == NULL)
1280 goto error;
1281
1282 assoc_array_apply_edit(edit);
1283 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1284 ret = 0;
1285
1286error:
1287 up_write(&keyring->sem);
1288 return ret;
1289}
1290EXPORT_SYMBOL(key_unlink);
1291
1292/**
1293 * keyring_clear - Clear a keyring
1294 * @keyring: The keyring to clear.
1295 *
1296 * Clear the contents of the specified keyring.
1297 *
1298 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1299 */
1300int keyring_clear(struct key *keyring)
1301{
1302 struct assoc_array_edit *edit;
1303 int ret;
1304
1305 if (keyring->type != &key_type_keyring)
1306 return -ENOTDIR;
1307
1308 down_write(&keyring->sem);
1309
1310 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1311 if (IS_ERR(edit)) {
1312 ret = PTR_ERR(edit);
1313 } else {
1314 if (edit)
1315 assoc_array_apply_edit(edit);
1316 key_payload_reserve(keyring, 0);
1317 ret = 0;
1318 }
1319
1320 up_write(&keyring->sem);
1321 return ret;
1322}
1323EXPORT_SYMBOL(keyring_clear);
1324
1325/*
1326 * Dispose of the links from a revoked keyring.
1327 *
1328 * This is called with the key sem write-locked.
1329 */
1330static void keyring_revoke(struct key *keyring)
1331{
1332 struct assoc_array_edit *edit;
1333
1334 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1335 if (!IS_ERR(edit)) {
1336 if (edit)
1337 assoc_array_apply_edit(edit);
1338 key_payload_reserve(keyring, 0);
1339 }
1340}
1341
1342static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1343{
1344 struct key *key = keyring_ptr_to_key(object);
1345 time_t *limit = iterator_data;
1346
1347 if (key_is_dead(key, *limit))
1348 return false;
1349 key_get(key);
1350 return true;
1351}
1352
1353static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1354{
1355 const struct key *key = keyring_ptr_to_key(object);
1356 time_t *limit = iterator_data;
1357
1358 key_check(key);
1359 return key_is_dead(key, *limit);
1360}
1361
1362/*
1363 * Garbage collect pointers from a keyring.
1364 *
1365 * Not called with any locks held. The keyring's key struct will not be
1366 * deallocated under us as only our caller may deallocate it.
1367 */
1368void keyring_gc(struct key *keyring, time_t limit)
1369{
1370 int result;
1371
1372 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1373
1374 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1375 (1 << KEY_FLAG_REVOKED)))
1376 goto dont_gc;
1377
1378 /* scan the keyring looking for dead keys */
1379 rcu_read_lock();
1380 result = assoc_array_iterate(&keyring->keys,
1381 keyring_gc_check_iterator, &limit);
1382 rcu_read_unlock();
1383 if (result == true)
1384 goto do_gc;
1385
1386dont_gc:
1387 kleave(" [no gc]");
1388 return;
1389
1390do_gc:
1391 down_write(&keyring->sem);
1392 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1393 keyring_gc_select_iterator, &limit);
1394 up_write(&keyring->sem);
1395 kleave(" [gc]");
1396}
1/* Keyring handling
2 *
3 * Copyright (C) 2004-2005, 2008, 2013 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#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/security.h>
17#include <linux/seq_file.h>
18#include <linux/err.h>
19#include <keys/keyring-type.h>
20#include <keys/user-type.h>
21#include <linux/assoc_array_priv.h>
22#include <linux/uaccess.h>
23#include "internal.h"
24
25/*
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
28 */
29#define KEYRING_SEARCH_MAX_DEPTH 6
30
31/*
32 * We keep all named keyrings in a hash to speed looking them up.
33 */
34#define KEYRING_NAME_HASH_SIZE (1 << 5)
35
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
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++)
66 bucket += (unsigned char)*desc;
67
68 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
69}
70
71/*
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.
75 */
76static int keyring_preparse(struct key_preparsed_payload *prep);
77static void keyring_free_preparse(struct key_preparsed_payload *prep);
78static int keyring_instantiate(struct key *keyring,
79 struct key_preparsed_payload *prep);
80static void keyring_revoke(struct key *keyring);
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",
88 .def_datalen = 0,
89 .preparse = keyring_preparse,
90 .free_preparse = keyring_free_preparse,
91 .instantiate = keyring_instantiate,
92 .revoke = keyring_revoke,
93 .destroy = keyring_destroy,
94 .describe = keyring_describe,
95 .read = keyring_read,
96};
97EXPORT_SYMBOL(key_type_keyring);
98
99/*
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
102 */
103static DECLARE_RWSEM(keyring_serialise_link_sem);
104
105/*
106 * Publish the name of a keyring so that it can be found by name (if it has
107 * one).
108 */
109static void keyring_publish_name(struct key *keyring)
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
121 list_add_tail(&keyring->name_link,
122 &keyring_name_hash[bucket]);
123
124 write_unlock(&keyring_name_lock);
125 }
126}
127
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
143/*
144 * Initialise a keyring.
145 *
146 * Returns 0 on success, -EINVAL if given any data.
147 */
148static int keyring_instantiate(struct key *keyring,
149 struct key_preparsed_payload *prep)
150{
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;
155}
156
157/*
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;
174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
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 */
208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
211 return (hash + (hash << level_shift)) & ~fan_mask;
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.
229 */
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)
279{
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;
287}
288
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 */
293static int keyring_diff_objects(const void *object, const void *data)
294{
295 const struct key *key_a = keyring_ptr_to_key(object);
296 const struct keyring_index_key *a = &key_a->index_key;
297 const struct keyring_index_key *b = data;
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
376/*
377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
378 * and dispose of its data.
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.
384 */
385static void keyring_destroy(struct key *keyring)
386{
387 if (keyring->description) {
388 write_lock(&keyring_name_lock);
389
390 if (keyring->name_link.next != NULL &&
391 !list_empty(&keyring->name_link))
392 list_del(&keyring->name_link);
393
394 write_unlock(&keyring_name_lock);
395 }
396
397 if (keyring->restrict_link) {
398 struct key_restriction *keyres = keyring->restrict_link;
399
400 key_put(keyres->key);
401 kfree(keyres);
402 }
403
404 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
405}
406
407/*
408 * Describe a keyring for /proc.
409 */
410static void keyring_describe(const struct key *keyring, struct seq_file *m)
411{
412 if (keyring->description)
413 seq_puts(m, keyring->description);
414 else
415 seq_puts(m, "[anon]");
416
417 if (key_is_positive(keyring)) {
418 if (keyring->keys.nr_leaves_on_tree != 0)
419 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
420 else
421 seq_puts(m, ": empty");
422 }
423}
424
425struct keyring_read_iterator_context {
426 size_t buflen;
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}",
438 key->type->name, key->serial, ctx->count, ctx->buflen);
439
440 if (ctx->count >= ctx->buflen)
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
451/*
452 * Read a list of key IDs from the keyring's contents in binary form
453 *
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.
457 */
458static long keyring_read(const struct key *keyring,
459 char __user *buffer, size_t buflen)
460{
461 struct keyring_read_iterator_context ctx;
462 long ret;
463
464 kenter("{%d},,%zu", key_serial(keyring), buflen);
465
466 if (buflen & (sizeof(key_serial_t) - 1))
467 return -EINVAL;
468
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 }
480 }
481
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;
489}
490
491/*
492 * Allocate a keyring and link into the destination keyring.
493 */
494struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
495 const struct cred *cred, key_perm_t perm,
496 unsigned long flags,
497 struct key_restriction *restrict_link,
498 struct key *dest)
499{
500 struct key *keyring;
501 int ret;
502
503 keyring = key_alloc(&key_type_keyring, description,
504 uid, gid, cred, perm, flags, restrict_link);
505 if (!IS_ERR(keyring)) {
506 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
507 if (ret < 0) {
508 key_put(keyring);
509 keyring = ERR_PTR(ret);
510 }
511 }
512
513 return keyring;
514}
515EXPORT_SYMBOL(keyring_alloc);
516
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.
521 * @payload: The payload of the key intended to be added.
522 * @data: Additional data for evaluating restriction.
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 *
528 * This is meant to be stored in a key_restriction structure which is passed
529 * in the restrict_link parameter to keyring_alloc().
530 */
531int restrict_link_reject(struct key *keyring,
532 const struct key_type *type,
533 const union key_payload *payload,
534 struct key *restriction_key)
535{
536 return -EPERM;
537}
538
539/*
540 * By default, we keys found by getting an exact match on their descriptions.
541 */
542bool key_default_cmp(const struct key *key,
543 const struct key_match_data *match_data)
544{
545 return strcmp(key->description, match_data->raw_data) == 0;
546}
547
548/*
549 * Iteration function to consider each key found.
550 */
551static int keyring_search_iterator(const void *object, void *iterator_data)
552{
553 struct keyring_search_context *ctx = iterator_data;
554 const struct key *key = keyring_ptr_to_key(object);
555 unsigned long kflags = READ_ONCE(key->flags);
556 short state = READ_ONCE(key->state);
557
558 kenter("{%d}", key->serial);
559
560 /* ignore keys not of this type */
561 if (key->type != ctx->index_key.type) {
562 kleave(" = 0 [!type]");
563 return 0;
564 }
565
566 /* skip invalidated, revoked and expired keys */
567 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
568 time64_t expiry = READ_ONCE(key->expiry);
569
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 }
576
577 if (expiry && ctx->now >= expiry) {
578 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
579 ctx->result = ERR_PTR(-EKEYEXPIRED);
580 kleave(" = %d [expire]", ctx->skipped_ret);
581 goto skipped;
582 }
583 }
584
585 /* keys that don't match */
586 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
587 kleave(" = 0 [!match]");
588 return 0;
589 }
590
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),
594 ctx->cred, KEY_NEED_SEARCH) < 0) {
595 ctx->result = ERR_PTR(-EACCES);
596 kleave(" = %d [!perm]", ctx->skipped_ret);
597 goto skipped;
598 }
599
600 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
601 /* we set a different error code if we pass a negative key */
602 if (state < 0) {
603 ctx->result = ERR_PTR(state);
604 kleave(" = %d [neg]", ctx->skipped_ret);
605 goto skipped;
606 }
607 }
608
609 /* Found */
610 ctx->result = make_key_ref(key, ctx->possessed);
611 kleave(" = 1 [found]");
612 return 1;
613
614skipped:
615 return ctx->skipped_ret;
616}
617
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{
625 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
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}
635
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];
648
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;
654
655 kenter("{%d},{%s,%s}",
656 keyring->serial,
657 ctx->index_key.type->name,
658 ctx->index_key.description);
659
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
664 if (ctx->index_key.description)
665 ctx->index_key.desc_len = strlen(ctx->index_key.description);
666
667 /* Check to see if this top-level keyring is what we are looking for
668 * and whether it is valid or not.
669 */
670 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
671 keyring_compare_object(keyring, &ctx->index_key)) {
672 ctx->skipped_ret = 2;
673 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
674 case 1:
675 goto found;
676 case 2:
677 return false;
678 default:
679 break;
680 }
681 }
682
683 ctx->skipped_ret = 0;
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))
696 goto found;
697
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 */
706 ptr = READ_ONCE(keyring->keys.root);
707 if (!ptr)
708 goto not_this_keyring;
709
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.
714 */
715 shortcut = assoc_array_ptr_to_shortcut(ptr);
716 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
717 goto not_this_keyring;
718
719 ptr = READ_ONCE(shortcut->next_node);
720 node = assoc_array_ptr_to_node(ptr);
721 goto begin_node;
722 }
723
724 node = assoc_array_ptr_to_node(ptr);
725 ptr = node->slots[0];
726 if (!assoc_array_ptr_is_meta(ptr))
727 goto begin_node;
728
729descend_to_node:
730 /* Descend to a more distal node in this keyring's content tree and go
731 * through that.
732 */
733 kdebug("descend");
734 if (assoc_array_ptr_is_shortcut(ptr)) {
735 shortcut = assoc_array_ptr_to_shortcut(ptr);
736 ptr = READ_ONCE(shortcut->next_node);
737 BUG_ON(!assoc_array_ptr_is_node(ptr));
738 }
739 node = assoc_array_ptr_to_node(ptr);
740
741begin_node:
742 kdebug("begin_node");
743 slot = 0;
744ascend_to_node:
745 /* Go through the slots in a node */
746 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
747 ptr = READ_ONCE(node->slots[slot]);
748
749 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
750 goto descend_to_node;
751
752 if (!keyring_ptr_is_keyring(ptr))
753 continue;
754
755 key = keyring_ptr_to_key(ptr);
756
757 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
758 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
759 ctx->result = ERR_PTR(-ELOOP);
760 return false;
761 }
762 goto not_this_keyring;
763 }
764
765 /* Search a nested keyring */
766 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
767 key_task_permission(make_key_ref(key, ctx->possessed),
768 ctx->cred, KEY_NEED_SEARCH) < 0)
769 continue;
770
771 /* stack the current position */
772 stack[sp].keyring = keyring;
773 stack[sp].node = node;
774 stack[sp].slot = slot;
775 sp++;
776
777 /* begin again with the new keyring */
778 keyring = key;
779 goto descend_to_keyring;
780 }
781
782 /* We've dealt with all the slots in the current node, so now we need
783 * to ascend to the parent and continue processing there.
784 */
785 ptr = READ_ONCE(node->back_pointer);
786 slot = node->parent_slot;
787
788 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
789 shortcut = assoc_array_ptr_to_shortcut(ptr);
790 ptr = READ_ONCE(shortcut->back_pointer);
791 slot = shortcut->parent_slot;
792 }
793 if (!ptr)
794 goto not_this_keyring;
795 node = assoc_array_ptr_to_node(ptr);
796 slot++;
797
798 /* If we've ascended to the root (zero backpointer), we must have just
799 * finished processing the leftmost branch rather than the root slots -
800 * so there can't be any more keyrings for us to find.
801 */
802 if (node->back_pointer) {
803 kdebug("ascend %d", slot);
804 goto ascend_to_node;
805 }
806
807 /* The keyring we're looking at was disqualified or didn't contain a
808 * matching key.
809 */
810not_this_keyring:
811 kdebug("not_this_keyring %d", sp);
812 if (sp <= 0) {
813 kleave(" = false");
814 return false;
815 }
816
817 /* Resume the processing of a keyring higher up in the tree */
818 sp--;
819 keyring = stack[sp].keyring;
820 node = stack[sp].node;
821 slot = stack[sp].slot + 1;
822 kdebug("ascend to %d [%d]", keyring->serial, slot);
823 goto ascend_to_node;
824
825 /* We found a viable match */
826found:
827 key = key_ref_to_ptr(ctx->result);
828 key_check(key);
829 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
830 key->last_used_at = ctx->now;
831 keyring->last_used_at = ctx->now;
832 while (sp > 0)
833 stack[--sp].keyring->last_used_at = ctx->now;
834 }
835 kleave(" = true");
836 return true;
837}
838
839/**
840 * keyring_search_aux - Search a keyring tree for a key matching some criteria
841 * @keyring_ref: A pointer to the keyring with possession indicator.
842 * @ctx: The keyring search context.
843 *
844 * Search the supplied keyring tree for a key that matches the criteria given.
845 * The root keyring and any linked keyrings must grant Search permission to the
846 * caller to be searchable and keys can only be found if they too grant Search
847 * to the caller. The possession flag on the root keyring pointer controls use
848 * of the possessor bits in permissions checking of the entire tree. In
849 * addition, the LSM gets to forbid keyring searches and key matches.
850 *
851 * The search is performed as a breadth-then-depth search up to the prescribed
852 * limit (KEYRING_SEARCH_MAX_DEPTH).
853 *
854 * Keys are matched to the type provided and are then filtered by the match
855 * function, which is given the description to use in any way it sees fit. The
856 * match function may use any attributes of a key that it wishes to to
857 * determine the match. Normally the match function from the key type would be
858 * used.
859 *
860 * RCU can be used to prevent the keyring key lists from disappearing without
861 * the need to take lots of locks.
862 *
863 * Returns a pointer to the found key and increments the key usage count if
864 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
865 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
866 * specified keyring wasn't a keyring.
867 *
868 * In the case of a successful return, the possession attribute from
869 * @keyring_ref is propagated to the returned key reference.
870 */
871key_ref_t keyring_search_aux(key_ref_t keyring_ref,
872 struct keyring_search_context *ctx)
873{
874 struct key *keyring;
875 long err;
876
877 ctx->iterator = keyring_search_iterator;
878 ctx->possessed = is_key_possessed(keyring_ref);
879 ctx->result = ERR_PTR(-EAGAIN);
880
881 keyring = key_ref_to_ptr(keyring_ref);
882 key_check(keyring);
883
884 if (keyring->type != &key_type_keyring)
885 return ERR_PTR(-ENOTDIR);
886
887 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
888 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
889 if (err < 0)
890 return ERR_PTR(err);
891 }
892
893 rcu_read_lock();
894 ctx->now = ktime_get_real_seconds();
895 if (search_nested_keyrings(keyring, ctx))
896 __key_get(key_ref_to_ptr(ctx->result));
897 rcu_read_unlock();
898 return ctx->result;
899}
900
901/**
902 * keyring_search - Search the supplied keyring tree for a matching key
903 * @keyring: The root of the keyring tree to be searched.
904 * @type: The type of keyring we want to find.
905 * @description: The name of the keyring we want to find.
906 *
907 * As keyring_search_aux() above, but using the current task's credentials and
908 * type's default matching function and preferred search method.
909 */
910key_ref_t keyring_search(key_ref_t keyring,
911 struct key_type *type,
912 const char *description)
913{
914 struct keyring_search_context ctx = {
915 .index_key.type = type,
916 .index_key.description = description,
917 .cred = current_cred(),
918 .match_data.cmp = key_default_cmp,
919 .match_data.raw_data = description,
920 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
921 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
922 };
923 key_ref_t key;
924 int ret;
925
926 if (type->match_preparse) {
927 ret = type->match_preparse(&ctx.match_data);
928 if (ret < 0)
929 return ERR_PTR(ret);
930 }
931
932 key = keyring_search_aux(keyring, &ctx);
933
934 if (type->match_free)
935 type->match_free(&ctx.match_data);
936 return key;
937}
938EXPORT_SYMBOL(keyring_search);
939
940static struct key_restriction *keyring_restriction_alloc(
941 key_restrict_link_func_t check)
942{
943 struct key_restriction *keyres =
944 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
945
946 if (!keyres)
947 return ERR_PTR(-ENOMEM);
948
949 keyres->check = check;
950
951 return keyres;
952}
953
954/*
955 * Semaphore to serialise restriction setup to prevent reference count
956 * cycles through restriction key pointers.
957 */
958static DECLARE_RWSEM(keyring_serialise_restrict_sem);
959
960/*
961 * Check for restriction cycles that would prevent keyring garbage collection.
962 * keyring_serialise_restrict_sem must be held.
963 */
964static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
965 struct key_restriction *keyres)
966{
967 while (keyres && keyres->key &&
968 keyres->key->type == &key_type_keyring) {
969 if (keyres->key == dest_keyring)
970 return true;
971
972 keyres = keyres->key->restrict_link;
973 }
974
975 return false;
976}
977
978/**
979 * keyring_restrict - Look up and apply a restriction to a keyring
980 *
981 * @keyring: The keyring to be restricted
982 * @restriction: The restriction options to apply to the keyring
983 */
984int keyring_restrict(key_ref_t keyring_ref, const char *type,
985 const char *restriction)
986{
987 struct key *keyring;
988 struct key_type *restrict_type = NULL;
989 struct key_restriction *restrict_link;
990 int ret = 0;
991
992 keyring = key_ref_to_ptr(keyring_ref);
993 key_check(keyring);
994
995 if (keyring->type != &key_type_keyring)
996 return -ENOTDIR;
997
998 if (!type) {
999 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1000 } else {
1001 restrict_type = key_type_lookup(type);
1002
1003 if (IS_ERR(restrict_type))
1004 return PTR_ERR(restrict_type);
1005
1006 if (!restrict_type->lookup_restriction) {
1007 ret = -ENOENT;
1008 goto error;
1009 }
1010
1011 restrict_link = restrict_type->lookup_restriction(restriction);
1012 }
1013
1014 if (IS_ERR(restrict_link)) {
1015 ret = PTR_ERR(restrict_link);
1016 goto error;
1017 }
1018
1019 down_write(&keyring->sem);
1020 down_write(&keyring_serialise_restrict_sem);
1021
1022 if (keyring->restrict_link)
1023 ret = -EEXIST;
1024 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1025 ret = -EDEADLK;
1026 else
1027 keyring->restrict_link = restrict_link;
1028
1029 up_write(&keyring_serialise_restrict_sem);
1030 up_write(&keyring->sem);
1031
1032 if (ret < 0) {
1033 key_put(restrict_link->key);
1034 kfree(restrict_link);
1035 }
1036
1037error:
1038 if (restrict_type)
1039 key_type_put(restrict_type);
1040
1041 return ret;
1042}
1043EXPORT_SYMBOL(keyring_restrict);
1044
1045/*
1046 * Search the given keyring for a key that might be updated.
1047 *
1048 * The caller must guarantee that the keyring is a keyring and that the
1049 * permission is granted to modify the keyring as no check is made here. The
1050 * caller must also hold a lock on the keyring semaphore.
1051 *
1052 * Returns a pointer to the found key with usage count incremented if
1053 * successful and returns NULL if not found. Revoked and invalidated keys are
1054 * skipped over.
1055 *
1056 * If successful, the possession indicator is propagated from the keyring ref
1057 * to the returned key reference.
1058 */
1059key_ref_t find_key_to_update(key_ref_t keyring_ref,
1060 const struct keyring_index_key *index_key)
1061{
1062 struct key *keyring, *key;
1063 const void *object;
1064
1065 keyring = key_ref_to_ptr(keyring_ref);
1066
1067 kenter("{%d},{%s,%s}",
1068 keyring->serial, index_key->type->name, index_key->description);
1069
1070 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1071 index_key);
1072
1073 if (object)
1074 goto found;
1075
1076 kleave(" = NULL");
1077 return NULL;
1078
1079found:
1080 key = keyring_ptr_to_key(object);
1081 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1082 (1 << KEY_FLAG_REVOKED))) {
1083 kleave(" = NULL [x]");
1084 return NULL;
1085 }
1086 __key_get(key);
1087 kleave(" = {%d}", key->serial);
1088 return make_key_ref(key, is_key_possessed(keyring_ref));
1089}
1090
1091/*
1092 * Find a keyring with the specified name.
1093 *
1094 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1095 * user in the current user namespace are considered. If @uid_keyring is %true,
1096 * the keyring additionally must have been allocated as a user or user session
1097 * keyring; otherwise, it must grant Search permission directly to the caller.
1098 *
1099 * Returns a pointer to the keyring with the keyring's refcount having being
1100 * incremented on success. -ENOKEY is returned if a key could not be found.
1101 */
1102struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1103{
1104 struct key *keyring;
1105 int bucket;
1106
1107 if (!name)
1108 return ERR_PTR(-EINVAL);
1109
1110 bucket = keyring_hash(name);
1111
1112 read_lock(&keyring_name_lock);
1113
1114 if (keyring_name_hash[bucket].next) {
1115 /* search this hash bucket for a keyring with a matching name
1116 * that's readable and that hasn't been revoked */
1117 list_for_each_entry(keyring,
1118 &keyring_name_hash[bucket],
1119 name_link
1120 ) {
1121 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
1122 continue;
1123
1124 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1125 continue;
1126
1127 if (strcmp(keyring->description, name) != 0)
1128 continue;
1129
1130 if (uid_keyring) {
1131 if (!test_bit(KEY_FLAG_UID_KEYRING,
1132 &keyring->flags))
1133 continue;
1134 } else {
1135 if (key_permission(make_key_ref(keyring, 0),
1136 KEY_NEED_SEARCH) < 0)
1137 continue;
1138 }
1139
1140 /* we've got a match but we might end up racing with
1141 * key_cleanup() if the keyring is currently 'dead'
1142 * (ie. it has a zero usage count) */
1143 if (!refcount_inc_not_zero(&keyring->usage))
1144 continue;
1145 keyring->last_used_at = ktime_get_real_seconds();
1146 goto out;
1147 }
1148 }
1149
1150 keyring = ERR_PTR(-ENOKEY);
1151out:
1152 read_unlock(&keyring_name_lock);
1153 return keyring;
1154}
1155
1156static int keyring_detect_cycle_iterator(const void *object,
1157 void *iterator_data)
1158{
1159 struct keyring_search_context *ctx = iterator_data;
1160 const struct key *key = keyring_ptr_to_key(object);
1161
1162 kenter("{%d}", key->serial);
1163
1164 /* We might get a keyring with matching index-key that is nonetheless a
1165 * different keyring. */
1166 if (key != ctx->match_data.raw_data)
1167 return 0;
1168
1169 ctx->result = ERR_PTR(-EDEADLK);
1170 return 1;
1171}
1172
1173/*
1174 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1175 * tree A at the topmost level (ie: as a direct child of A).
1176 *
1177 * Since we are adding B to A at the top level, checking for cycles should just
1178 * be a matter of seeing if node A is somewhere in tree B.
1179 */
1180static int keyring_detect_cycle(struct key *A, struct key *B)
1181{
1182 struct keyring_search_context ctx = {
1183 .index_key = A->index_key,
1184 .match_data.raw_data = A,
1185 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1186 .iterator = keyring_detect_cycle_iterator,
1187 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1188 KEYRING_SEARCH_NO_UPDATE_TIME |
1189 KEYRING_SEARCH_NO_CHECK_PERM |
1190 KEYRING_SEARCH_DETECT_TOO_DEEP),
1191 };
1192
1193 rcu_read_lock();
1194 search_nested_keyrings(B, &ctx);
1195 rcu_read_unlock();
1196 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1197}
1198
1199/*
1200 * Preallocate memory so that a key can be linked into to a keyring.
1201 */
1202int __key_link_begin(struct key *keyring,
1203 const struct keyring_index_key *index_key,
1204 struct assoc_array_edit **_edit)
1205 __acquires(&keyring->sem)
1206 __acquires(&keyring_serialise_link_sem)
1207{
1208 struct assoc_array_edit *edit;
1209 int ret;
1210
1211 kenter("%d,%s,%s,",
1212 keyring->serial, index_key->type->name, index_key->description);
1213
1214 BUG_ON(index_key->desc_len == 0);
1215
1216 if (keyring->type != &key_type_keyring)
1217 return -ENOTDIR;
1218
1219 down_write(&keyring->sem);
1220
1221 ret = -EKEYREVOKED;
1222 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1223 goto error_krsem;
1224
1225 /* serialise link/link calls to prevent parallel calls causing a cycle
1226 * when linking two keyring in opposite orders */
1227 if (index_key->type == &key_type_keyring)
1228 down_write(&keyring_serialise_link_sem);
1229
1230 /* Create an edit script that will insert/replace the key in the
1231 * keyring tree.
1232 */
1233 edit = assoc_array_insert(&keyring->keys,
1234 &keyring_assoc_array_ops,
1235 index_key,
1236 NULL);
1237 if (IS_ERR(edit)) {
1238 ret = PTR_ERR(edit);
1239 goto error_sem;
1240 }
1241
1242 /* If we're not replacing a link in-place then we're going to need some
1243 * extra quota.
1244 */
1245 if (!edit->dead_leaf) {
1246 ret = key_payload_reserve(keyring,
1247 keyring->datalen + KEYQUOTA_LINK_BYTES);
1248 if (ret < 0)
1249 goto error_cancel;
1250 }
1251
1252 *_edit = edit;
1253 kleave(" = 0");
1254 return 0;
1255
1256error_cancel:
1257 assoc_array_cancel_edit(edit);
1258error_sem:
1259 if (index_key->type == &key_type_keyring)
1260 up_write(&keyring_serialise_link_sem);
1261error_krsem:
1262 up_write(&keyring->sem);
1263 kleave(" = %d", ret);
1264 return ret;
1265}
1266
1267/*
1268 * Check already instantiated keys aren't going to be a problem.
1269 *
1270 * The caller must have called __key_link_begin(). Don't need to call this for
1271 * keys that were created since __key_link_begin() was called.
1272 */
1273int __key_link_check_live_key(struct key *keyring, struct key *key)
1274{
1275 if (key->type == &key_type_keyring)
1276 /* check that we aren't going to create a cycle by linking one
1277 * keyring to another */
1278 return keyring_detect_cycle(keyring, key);
1279 return 0;
1280}
1281
1282/*
1283 * Link a key into to a keyring.
1284 *
1285 * Must be called with __key_link_begin() having being called. Discards any
1286 * already extant link to matching key if there is one, so that each keyring
1287 * holds at most one link to any given key of a particular type+description
1288 * combination.
1289 */
1290void __key_link(struct key *key, struct assoc_array_edit **_edit)
1291{
1292 __key_get(key);
1293 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1294 assoc_array_apply_edit(*_edit);
1295 *_edit = NULL;
1296}
1297
1298/*
1299 * Finish linking a key into to a keyring.
1300 *
1301 * Must be called with __key_link_begin() having being called.
1302 */
1303void __key_link_end(struct key *keyring,
1304 const struct keyring_index_key *index_key,
1305 struct assoc_array_edit *edit)
1306 __releases(&keyring->sem)
1307 __releases(&keyring_serialise_link_sem)
1308{
1309 BUG_ON(index_key->type == NULL);
1310 kenter("%d,%s,", keyring->serial, index_key->type->name);
1311
1312 if (index_key->type == &key_type_keyring)
1313 up_write(&keyring_serialise_link_sem);
1314
1315 if (edit) {
1316 if (!edit->dead_leaf) {
1317 key_payload_reserve(keyring,
1318 keyring->datalen - KEYQUOTA_LINK_BYTES);
1319 }
1320 assoc_array_cancel_edit(edit);
1321 }
1322 up_write(&keyring->sem);
1323}
1324
1325/*
1326 * Check addition of keys to restricted keyrings.
1327 */
1328static int __key_link_check_restriction(struct key *keyring, struct key *key)
1329{
1330 if (!keyring->restrict_link || !keyring->restrict_link->check)
1331 return 0;
1332 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1333 keyring->restrict_link->key);
1334}
1335
1336/**
1337 * key_link - Link a key to a keyring
1338 * @keyring: The keyring to make the link in.
1339 * @key: The key to link to.
1340 *
1341 * Make a link in a keyring to a key, such that the keyring holds a reference
1342 * on that key and the key can potentially be found by searching that keyring.
1343 *
1344 * This function will write-lock the keyring's semaphore and will consume some
1345 * of the user's key data quota to hold the link.
1346 *
1347 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1348 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1349 * full, -EDQUOT if there is insufficient key data quota remaining to add
1350 * another link or -ENOMEM if there's insufficient memory.
1351 *
1352 * It is assumed that the caller has checked that it is permitted for a link to
1353 * be made (the keyring should have Write permission and the key Link
1354 * permission).
1355 */
1356int key_link(struct key *keyring, struct key *key)
1357{
1358 struct assoc_array_edit *edit;
1359 int ret;
1360
1361 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1362
1363 key_check(keyring);
1364 key_check(key);
1365
1366 ret = __key_link_begin(keyring, &key->index_key, &edit);
1367 if (ret == 0) {
1368 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1369 ret = __key_link_check_restriction(keyring, key);
1370 if (ret == 0)
1371 ret = __key_link_check_live_key(keyring, key);
1372 if (ret == 0)
1373 __key_link(key, &edit);
1374 __key_link_end(keyring, &key->index_key, edit);
1375 }
1376
1377 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1378 return ret;
1379}
1380EXPORT_SYMBOL(key_link);
1381
1382/**
1383 * key_unlink - Unlink the first link to a key from a keyring.
1384 * @keyring: The keyring to remove the link from.
1385 * @key: The key the link is to.
1386 *
1387 * Remove a link from a keyring to a key.
1388 *
1389 * This function will write-lock the keyring's semaphore.
1390 *
1391 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1392 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1393 * memory.
1394 *
1395 * It is assumed that the caller has checked that it is permitted for a link to
1396 * be removed (the keyring should have Write permission; no permissions are
1397 * required on the key).
1398 */
1399int key_unlink(struct key *keyring, struct key *key)
1400{
1401 struct assoc_array_edit *edit;
1402 int ret;
1403
1404 key_check(keyring);
1405 key_check(key);
1406
1407 if (keyring->type != &key_type_keyring)
1408 return -ENOTDIR;
1409
1410 down_write(&keyring->sem);
1411
1412 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1413 &key->index_key);
1414 if (IS_ERR(edit)) {
1415 ret = PTR_ERR(edit);
1416 goto error;
1417 }
1418 ret = -ENOENT;
1419 if (edit == NULL)
1420 goto error;
1421
1422 assoc_array_apply_edit(edit);
1423 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1424 ret = 0;
1425
1426error:
1427 up_write(&keyring->sem);
1428 return ret;
1429}
1430EXPORT_SYMBOL(key_unlink);
1431
1432/**
1433 * keyring_clear - Clear a keyring
1434 * @keyring: The keyring to clear.
1435 *
1436 * Clear the contents of the specified keyring.
1437 *
1438 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1439 */
1440int keyring_clear(struct key *keyring)
1441{
1442 struct assoc_array_edit *edit;
1443 int ret;
1444
1445 if (keyring->type != &key_type_keyring)
1446 return -ENOTDIR;
1447
1448 down_write(&keyring->sem);
1449
1450 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1451 if (IS_ERR(edit)) {
1452 ret = PTR_ERR(edit);
1453 } else {
1454 if (edit)
1455 assoc_array_apply_edit(edit);
1456 key_payload_reserve(keyring, 0);
1457 ret = 0;
1458 }
1459
1460 up_write(&keyring->sem);
1461 return ret;
1462}
1463EXPORT_SYMBOL(keyring_clear);
1464
1465/*
1466 * Dispose of the links from a revoked keyring.
1467 *
1468 * This is called with the key sem write-locked.
1469 */
1470static void keyring_revoke(struct key *keyring)
1471{
1472 struct assoc_array_edit *edit;
1473
1474 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1475 if (!IS_ERR(edit)) {
1476 if (edit)
1477 assoc_array_apply_edit(edit);
1478 key_payload_reserve(keyring, 0);
1479 }
1480}
1481
1482static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1483{
1484 struct key *key = keyring_ptr_to_key(object);
1485 time64_t *limit = iterator_data;
1486
1487 if (key_is_dead(key, *limit))
1488 return false;
1489 key_get(key);
1490 return true;
1491}
1492
1493static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1494{
1495 const struct key *key = keyring_ptr_to_key(object);
1496 time64_t *limit = iterator_data;
1497
1498 key_check(key);
1499 return key_is_dead(key, *limit);
1500}
1501
1502/*
1503 * Garbage collect pointers from a keyring.
1504 *
1505 * Not called with any locks held. The keyring's key struct will not be
1506 * deallocated under us as only our caller may deallocate it.
1507 */
1508void keyring_gc(struct key *keyring, time64_t limit)
1509{
1510 int result;
1511
1512 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1513
1514 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1515 (1 << KEY_FLAG_REVOKED)))
1516 goto dont_gc;
1517
1518 /* scan the keyring looking for dead keys */
1519 rcu_read_lock();
1520 result = assoc_array_iterate(&keyring->keys,
1521 keyring_gc_check_iterator, &limit);
1522 rcu_read_unlock();
1523 if (result == true)
1524 goto do_gc;
1525
1526dont_gc:
1527 kleave(" [no gc]");
1528 return;
1529
1530do_gc:
1531 down_write(&keyring->sem);
1532 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1533 keyring_gc_select_iterator, &limit);
1534 up_write(&keyring->sem);
1535 kleave(" [gc]");
1536}
1537
1538/*
1539 * Garbage collect restriction pointers from a keyring.
1540 *
1541 * Keyring restrictions are associated with a key type, and must be cleaned
1542 * up if the key type is unregistered. The restriction is altered to always
1543 * reject additional keys so a keyring cannot be opened up by unregistering
1544 * a key type.
1545 *
1546 * Not called with any keyring locks held. The keyring's key struct will not
1547 * be deallocated under us as only our caller may deallocate it.
1548 *
1549 * The caller is required to hold key_types_sem and dead_type->sem. This is
1550 * fulfilled by key_gc_keytype() holding the locks on behalf of
1551 * key_garbage_collector(), which it invokes on a workqueue.
1552 */
1553void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1554{
1555 struct key_restriction *keyres;
1556
1557 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1558
1559 /*
1560 * keyring->restrict_link is only assigned at key allocation time
1561 * or with the key type locked, so the only values that could be
1562 * concurrently assigned to keyring->restrict_link are for key
1563 * types other than dead_type. Given this, it's ok to check
1564 * the key type before acquiring keyring->sem.
1565 */
1566 if (!dead_type || !keyring->restrict_link ||
1567 keyring->restrict_link->keytype != dead_type) {
1568 kleave(" [no restriction gc]");
1569 return;
1570 }
1571
1572 /* Lock the keyring to ensure that a link is not in progress */
1573 down_write(&keyring->sem);
1574
1575 keyres = keyring->restrict_link;
1576
1577 keyres->check = restrict_link_reject;
1578
1579 key_put(keyres->key);
1580 keyres->key = NULL;
1581 keyres->keytype = NULL;
1582
1583 up_write(&keyring->sem);
1584
1585 kleave(" [restriction gc]");
1586}