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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Keyring handling
3 *
4 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells ([email protected])
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/sched.h>
11#include <linux/slab.h>
12#include <linux/security.h>
13#include <linux/seq_file.h>
14#include <linux/err.h>
15#include <linux/user_namespace.h>
16#include <linux/nsproxy.h>
17#include <keys/keyring-type.h>
18#include <keys/user-type.h>
19#include <linux/assoc_array_priv.h>
20#include <linux/uaccess.h>
21#include <net/net_namespace.h>
22#include "internal.h"
23
24/*
25 * When plumbing the depths of the key tree, this sets a hard limit
26 * set on how deep we're willing to go.
27 */
28#define KEYRING_SEARCH_MAX_DEPTH 6
29
30/*
31 * We mark pointers we pass to the associative array with bit 1 set if
32 * they're keyrings and clear otherwise.
33 */
34#define KEYRING_PTR_SUBTYPE 0x2UL
35
36static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
37{
38 return (unsigned long)x & KEYRING_PTR_SUBTYPE;
39}
40static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
41{
42 void *object = assoc_array_ptr_to_leaf(x);
43 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
44}
45static inline void *keyring_key_to_ptr(struct key *key)
46{
47 if (key->type == &key_type_keyring)
48 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
49 return key;
50}
51
52static DEFINE_RWLOCK(keyring_name_lock);
53
54/*
55 * Clean up the bits of user_namespace that belong to us.
56 */
57void key_free_user_ns(struct user_namespace *ns)
58{
59 write_lock(&keyring_name_lock);
60 list_del_init(&ns->keyring_name_list);
61 write_unlock(&keyring_name_lock);
62
63 key_put(ns->user_keyring_register);
64#ifdef CONFIG_PERSISTENT_KEYRINGS
65 key_put(ns->persistent_keyring_register);
66#endif
67}
68
69/*
70 * The keyring key type definition. Keyrings are simply keys of this type and
71 * can be treated as ordinary keys in addition to having their own special
72 * operations.
73 */
74static int keyring_preparse(struct key_preparsed_payload *prep);
75static void keyring_free_preparse(struct key_preparsed_payload *prep);
76static int keyring_instantiate(struct key *keyring,
77 struct key_preparsed_payload *prep);
78static void keyring_revoke(struct key *keyring);
79static void keyring_destroy(struct key *keyring);
80static void keyring_describe(const struct key *keyring, struct seq_file *m);
81static long keyring_read(const struct key *keyring,
82 char *buffer, size_t buflen);
83
84struct key_type key_type_keyring = {
85 .name = "keyring",
86 .def_datalen = 0,
87 .preparse = keyring_preparse,
88 .free_preparse = keyring_free_preparse,
89 .instantiate = keyring_instantiate,
90 .revoke = keyring_revoke,
91 .destroy = keyring_destroy,
92 .describe = keyring_describe,
93 .read = keyring_read,
94};
95EXPORT_SYMBOL(key_type_keyring);
96
97/*
98 * Semaphore to serialise link/link calls to prevent two link calls in parallel
99 * introducing a cycle.
100 */
101static DEFINE_MUTEX(keyring_serialise_link_lock);
102
103/*
104 * Publish the name of a keyring so that it can be found by name (if it has
105 * one and it doesn't begin with a dot).
106 */
107static void keyring_publish_name(struct key *keyring)
108{
109 struct user_namespace *ns = current_user_ns();
110
111 if (keyring->description &&
112 keyring->description[0] &&
113 keyring->description[0] != '.') {
114 write_lock(&keyring_name_lock);
115 list_add_tail(&keyring->name_link, &ns->keyring_name_list);
116 write_unlock(&keyring_name_lock);
117 }
118}
119
120/*
121 * Preparse a keyring payload
122 */
123static int keyring_preparse(struct key_preparsed_payload *prep)
124{
125 return prep->datalen != 0 ? -EINVAL : 0;
126}
127
128/*
129 * Free a preparse of a user defined key payload
130 */
131static void keyring_free_preparse(struct key_preparsed_payload *prep)
132{
133}
134
135/*
136 * Initialise a keyring.
137 *
138 * Returns 0 on success, -EINVAL if given any data.
139 */
140static int keyring_instantiate(struct key *keyring,
141 struct key_preparsed_payload *prep)
142{
143 assoc_array_init(&keyring->keys);
144 /* make the keyring available by name if it has one */
145 keyring_publish_name(keyring);
146 return 0;
147}
148
149/*
150 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
151 * fold the carry back too, but that requires inline asm.
152 */
153static u64 mult_64x32_and_fold(u64 x, u32 y)
154{
155 u64 hi = (u64)(u32)(x >> 32) * y;
156 u64 lo = (u64)(u32)(x) * y;
157 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
158}
159
160/*
161 * Hash a key type and description.
162 */
163static void hash_key_type_and_desc(struct keyring_index_key *index_key)
164{
165 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
166 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
167 const char *description = index_key->description;
168 unsigned long hash, type;
169 u32 piece;
170 u64 acc;
171 int n, desc_len = index_key->desc_len;
172
173 type = (unsigned long)index_key->type;
174 acc = mult_64x32_and_fold(type, desc_len + 13);
175 acc = mult_64x32_and_fold(acc, 9207);
176 piece = (unsigned long)index_key->domain_tag;
177 acc = mult_64x32_and_fold(acc, piece);
178 acc = mult_64x32_and_fold(acc, 9207);
179
180 for (;;) {
181 n = desc_len;
182 if (n <= 0)
183 break;
184 if (n > 4)
185 n = 4;
186 piece = 0;
187 memcpy(&piece, description, n);
188 description += n;
189 desc_len -= n;
190 acc = mult_64x32_and_fold(acc, piece);
191 acc = mult_64x32_and_fold(acc, 9207);
192 }
193
194 /* Fold the hash down to 32 bits if need be. */
195 hash = acc;
196 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
197 hash ^= acc >> 32;
198
199 /* Squidge all the keyrings into a separate part of the tree to
200 * ordinary keys by making sure the lowest level segment in the hash is
201 * zero for keyrings and non-zero otherwise.
202 */
203 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
204 hash |= (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
205 else if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
206 hash = (hash + (hash << level_shift)) & ~fan_mask;
207 index_key->hash = hash;
208}
209
210/*
211 * Finalise an index key to include a part of the description actually in the
212 * index key, to set the domain tag and to calculate the hash.
213 */
214void key_set_index_key(struct keyring_index_key *index_key)
215{
216 static struct key_tag default_domain_tag = { .usage = REFCOUNT_INIT(1), };
217 size_t n = min_t(size_t, index_key->desc_len, sizeof(index_key->desc));
218
219 memcpy(index_key->desc, index_key->description, n);
220
221 if (!index_key->domain_tag) {
222 if (index_key->type->flags & KEY_TYPE_NET_DOMAIN)
223 index_key->domain_tag = current->nsproxy->net_ns->key_domain;
224 else
225 index_key->domain_tag = &default_domain_tag;
226 }
227
228 hash_key_type_and_desc(index_key);
229}
230
231/**
232 * key_put_tag - Release a ref on a tag.
233 * @tag: The tag to release.
234 *
235 * This releases a reference the given tag and returns true if that ref was the
236 * last one.
237 */
238bool key_put_tag(struct key_tag *tag)
239{
240 if (refcount_dec_and_test(&tag->usage)) {
241 kfree_rcu(tag, rcu);
242 return true;
243 }
244
245 return false;
246}
247
248/**
249 * key_remove_domain - Kill off a key domain and gc its keys
250 * @domain_tag: The domain tag to release.
251 *
252 * This marks a domain tag as being dead and releases a ref on it. If that
253 * wasn't the last reference, the garbage collector is poked to try and delete
254 * all keys that were in the domain.
255 */
256void key_remove_domain(struct key_tag *domain_tag)
257{
258 domain_tag->removed = true;
259 if (!key_put_tag(domain_tag))
260 key_schedule_gc_links();
261}
262
263/*
264 * Build the next index key chunk.
265 *
266 * We return it one word-sized chunk at a time.
267 */
268static unsigned long keyring_get_key_chunk(const void *data, int level)
269{
270 const struct keyring_index_key *index_key = data;
271 unsigned long chunk = 0;
272 const u8 *d;
273 int desc_len = index_key->desc_len, n = sizeof(chunk);
274 unsigned int offset;
275
276 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
277 switch (level) {
278 case 0:
279 return index_key->hash;
280 case 1:
281 return index_key->x;
282 case 2:
283 return (unsigned long)index_key->type;
284 case 3:
285 return (unsigned long)index_key->domain_tag;
286 default:
287 level -= 4;
288 offset = sizeof(index_key->desc) + level * sizeof(long);
289 if (desc_len <= offset)
290 return 0;
291
292 d = index_key->description + offset;
293 desc_len -= offset;
294 if (desc_len > n)
295 desc_len = n;
296 d += desc_len;
297 do {
298 chunk <<= 8;
299 chunk |= *--d;
300 } while (--desc_len > 0);
301 return chunk;
302 }
303}
304
305static unsigned long keyring_get_object_key_chunk(const void *object, int level)
306{
307 const struct key *key = keyring_ptr_to_key(object);
308 return keyring_get_key_chunk(&key->index_key, level);
309}
310
311static bool keyring_compare_object(const void *object, const void *data)
312{
313 const struct keyring_index_key *index_key = data;
314 const struct key *key = keyring_ptr_to_key(object);
315
316 return key->index_key.type == index_key->type &&
317 key->index_key.domain_tag == index_key->domain_tag &&
318 key->index_key.desc_len == index_key->desc_len &&
319 memcmp(key->index_key.description, index_key->description,
320 index_key->desc_len) == 0;
321}
322
323/*
324 * Compare the index keys of a pair of objects and determine the bit position
325 * at which they differ - if they differ.
326 */
327static int keyring_diff_objects(const void *object, const void *data)
328{
329 const struct key *key_a = keyring_ptr_to_key(object);
330 const struct keyring_index_key *a = &key_a->index_key;
331 const struct keyring_index_key *b = data;
332 unsigned long seg_a, seg_b;
333 int level, i;
334
335 level = 0;
336 seg_a = a->hash;
337 seg_b = b->hash;
338 if ((seg_a ^ seg_b) != 0)
339 goto differ;
340 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
341
342 /* The number of bits contributed by the hash is controlled by a
343 * constant in the assoc_array headers. Everything else thereafter we
344 * can deal with as being machine word-size dependent.
345 */
346 seg_a = a->x;
347 seg_b = b->x;
348 if ((seg_a ^ seg_b) != 0)
349 goto differ;
350 level += sizeof(unsigned long);
351
352 /* The next bit may not work on big endian */
353 seg_a = (unsigned long)a->type;
354 seg_b = (unsigned long)b->type;
355 if ((seg_a ^ seg_b) != 0)
356 goto differ;
357 level += sizeof(unsigned long);
358
359 seg_a = (unsigned long)a->domain_tag;
360 seg_b = (unsigned long)b->domain_tag;
361 if ((seg_a ^ seg_b) != 0)
362 goto differ;
363 level += sizeof(unsigned long);
364
365 i = sizeof(a->desc);
366 if (a->desc_len <= i)
367 goto same;
368
369 for (; i < a->desc_len; i++) {
370 seg_a = *(unsigned char *)(a->description + i);
371 seg_b = *(unsigned char *)(b->description + i);
372 if ((seg_a ^ seg_b) != 0)
373 goto differ_plus_i;
374 }
375
376same:
377 return -1;
378
379differ_plus_i:
380 level += i - (int)sizeof(a->desc);
381differ:
382 i = level * 8 + __ffs(seg_a ^ seg_b);
383 return i;
384}
385
386/*
387 * Free an object after stripping the keyring flag off of the pointer.
388 */
389static void keyring_free_object(void *object)
390{
391 key_put(keyring_ptr_to_key(object));
392}
393
394/*
395 * Operations for keyring management by the index-tree routines.
396 */
397static const struct assoc_array_ops keyring_assoc_array_ops = {
398 .get_key_chunk = keyring_get_key_chunk,
399 .get_object_key_chunk = keyring_get_object_key_chunk,
400 .compare_object = keyring_compare_object,
401 .diff_objects = keyring_diff_objects,
402 .free_object = keyring_free_object,
403};
404
405/*
406 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
407 * and dispose of its data.
408 *
409 * The garbage collector detects the final key_put(), removes the keyring from
410 * the serial number tree and then does RCU synchronisation before coming here,
411 * so we shouldn't need to worry about code poking around here with the RCU
412 * readlock held by this time.
413 */
414static void keyring_destroy(struct key *keyring)
415{
416 if (keyring->description) {
417 write_lock(&keyring_name_lock);
418
419 if (keyring->name_link.next != NULL &&
420 !list_empty(&keyring->name_link))
421 list_del(&keyring->name_link);
422
423 write_unlock(&keyring_name_lock);
424 }
425
426 if (keyring->restrict_link) {
427 struct key_restriction *keyres = keyring->restrict_link;
428
429 key_put(keyres->key);
430 kfree(keyres);
431 }
432
433 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
434}
435
436/*
437 * Describe a keyring for /proc.
438 */
439static void keyring_describe(const struct key *keyring, struct seq_file *m)
440{
441 if (keyring->description)
442 seq_puts(m, keyring->description);
443 else
444 seq_puts(m, "[anon]");
445
446 if (key_is_positive(keyring)) {
447 if (keyring->keys.nr_leaves_on_tree != 0)
448 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
449 else
450 seq_puts(m, ": empty");
451 }
452}
453
454struct keyring_read_iterator_context {
455 size_t buflen;
456 size_t count;
457 key_serial_t *buffer;
458};
459
460static int keyring_read_iterator(const void *object, void *data)
461{
462 struct keyring_read_iterator_context *ctx = data;
463 const struct key *key = keyring_ptr_to_key(object);
464
465 kenter("{%s,%d},,{%zu/%zu}",
466 key->type->name, key->serial, ctx->count, ctx->buflen);
467
468 if (ctx->count >= ctx->buflen)
469 return 1;
470
471 *ctx->buffer++ = key->serial;
472 ctx->count += sizeof(key->serial);
473 return 0;
474}
475
476/*
477 * Read a list of key IDs from the keyring's contents in binary form
478 *
479 * The keyring's semaphore is read-locked by the caller. This prevents someone
480 * from modifying it under us - which could cause us to read key IDs multiple
481 * times.
482 */
483static long keyring_read(const struct key *keyring,
484 char *buffer, size_t buflen)
485{
486 struct keyring_read_iterator_context ctx;
487 long ret;
488
489 kenter("{%d},,%zu", key_serial(keyring), buflen);
490
491 if (buflen & (sizeof(key_serial_t) - 1))
492 return -EINVAL;
493
494 /* Copy as many key IDs as fit into the buffer */
495 if (buffer && buflen) {
496 ctx.buffer = (key_serial_t *)buffer;
497 ctx.buflen = buflen;
498 ctx.count = 0;
499 ret = assoc_array_iterate(&keyring->keys,
500 keyring_read_iterator, &ctx);
501 if (ret < 0) {
502 kleave(" = %ld [iterate]", ret);
503 return ret;
504 }
505 }
506
507 /* Return the size of the buffer needed */
508 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
509 if (ret <= buflen)
510 kleave("= %ld [ok]", ret);
511 else
512 kleave("= %ld [buffer too small]", ret);
513 return ret;
514}
515
516/*
517 * Allocate a keyring and link into the destination keyring.
518 */
519struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
520 const struct cred *cred, key_perm_t perm,
521 unsigned long flags,
522 struct key_restriction *restrict_link,
523 struct key *dest)
524{
525 struct key *keyring;
526 int ret;
527
528 keyring = key_alloc(&key_type_keyring, description,
529 uid, gid, cred, perm, flags, restrict_link);
530 if (!IS_ERR(keyring)) {
531 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
532 if (ret < 0) {
533 key_put(keyring);
534 keyring = ERR_PTR(ret);
535 }
536 }
537
538 return keyring;
539}
540EXPORT_SYMBOL(keyring_alloc);
541
542/**
543 * restrict_link_reject - Give -EPERM to restrict link
544 * @keyring: The keyring being added to.
545 * @type: The type of key being added.
546 * @payload: The payload of the key intended to be added.
547 * @restriction_key: Keys providing additional data for evaluating restriction.
548 *
549 * Reject the addition of any links to a keyring. It can be overridden by
550 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
551 * adding a key to a keyring.
552 *
553 * This is meant to be stored in a key_restriction structure which is passed
554 * in the restrict_link parameter to keyring_alloc().
555 */
556int restrict_link_reject(struct key *keyring,
557 const struct key_type *type,
558 const union key_payload *payload,
559 struct key *restriction_key)
560{
561 return -EPERM;
562}
563
564/*
565 * By default, we keys found by getting an exact match on their descriptions.
566 */
567bool key_default_cmp(const struct key *key,
568 const struct key_match_data *match_data)
569{
570 return strcmp(key->description, match_data->raw_data) == 0;
571}
572
573/*
574 * Iteration function to consider each key found.
575 */
576static int keyring_search_iterator(const void *object, void *iterator_data)
577{
578 struct keyring_search_context *ctx = iterator_data;
579 const struct key *key = keyring_ptr_to_key(object);
580 unsigned long kflags = READ_ONCE(key->flags);
581 short state = key_read_state(key);
582
583 kenter("{%d}", key->serial);
584
585 /* ignore keys not of this type */
586 if (key->type != ctx->index_key.type) {
587 kleave(" = 0 [!type]");
588 return 0;
589 }
590
591 /* skip invalidated, revoked and expired keys */
592 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
593 time64_t expiry = READ_ONCE(key->expiry);
594
595 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
596 (1 << KEY_FLAG_REVOKED))) {
597 ctx->result = ERR_PTR(-EKEYREVOKED);
598 kleave(" = %d [invrev]", ctx->skipped_ret);
599 goto skipped;
600 }
601
602 if (expiry && ctx->now >= expiry) {
603 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
604 ctx->result = ERR_PTR(-EKEYEXPIRED);
605 kleave(" = %d [expire]", ctx->skipped_ret);
606 goto skipped;
607 }
608 }
609
610 /* keys that don't match */
611 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
612 kleave(" = 0 [!match]");
613 return 0;
614 }
615
616 /* key must have search permissions */
617 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
618 key_task_permission(make_key_ref(key, ctx->possessed),
619 ctx->cred, KEY_NEED_SEARCH) < 0) {
620 ctx->result = ERR_PTR(-EACCES);
621 kleave(" = %d [!perm]", ctx->skipped_ret);
622 goto skipped;
623 }
624
625 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
626 /* we set a different error code if we pass a negative key */
627 if (state < 0) {
628 ctx->result = ERR_PTR(state);
629 kleave(" = %d [neg]", ctx->skipped_ret);
630 goto skipped;
631 }
632 }
633
634 /* Found */
635 ctx->result = make_key_ref(key, ctx->possessed);
636 kleave(" = 1 [found]");
637 return 1;
638
639skipped:
640 return ctx->skipped_ret;
641}
642
643/*
644 * Search inside a keyring for a key. We can search by walking to it
645 * directly based on its index-key or we can iterate over the entire
646 * tree looking for it, based on the match function.
647 */
648static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
649{
650 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
651 const void *object;
652
653 object = assoc_array_find(&keyring->keys,
654 &keyring_assoc_array_ops,
655 &ctx->index_key);
656 return object ? ctx->iterator(object, ctx) : 0;
657 }
658 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
659}
660
661/*
662 * Search a tree of keyrings that point to other keyrings up to the maximum
663 * depth.
664 */
665static bool search_nested_keyrings(struct key *keyring,
666 struct keyring_search_context *ctx)
667{
668 struct {
669 struct key *keyring;
670 struct assoc_array_node *node;
671 int slot;
672 } stack[KEYRING_SEARCH_MAX_DEPTH];
673
674 struct assoc_array_shortcut *shortcut;
675 struct assoc_array_node *node;
676 struct assoc_array_ptr *ptr;
677 struct key *key;
678 int sp = 0, slot;
679
680 kenter("{%d},{%s,%s}",
681 keyring->serial,
682 ctx->index_key.type->name,
683 ctx->index_key.description);
684
685#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
686 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
687 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
688
689 if (ctx->index_key.description)
690 key_set_index_key(&ctx->index_key);
691
692 /* Check to see if this top-level keyring is what we are looking for
693 * and whether it is valid or not.
694 */
695 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
696 keyring_compare_object(keyring, &ctx->index_key)) {
697 ctx->skipped_ret = 2;
698 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
699 case 1:
700 goto found;
701 case 2:
702 return false;
703 default:
704 break;
705 }
706 }
707
708 ctx->skipped_ret = 0;
709
710 /* Start processing a new keyring */
711descend_to_keyring:
712 kdebug("descend to %d", keyring->serial);
713 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
714 (1 << KEY_FLAG_REVOKED)))
715 goto not_this_keyring;
716
717 /* Search through the keys in this keyring before its searching its
718 * subtrees.
719 */
720 if (search_keyring(keyring, ctx))
721 goto found;
722
723 /* Then manually iterate through the keyrings nested in this one.
724 *
725 * Start from the root node of the index tree. Because of the way the
726 * hash function has been set up, keyrings cluster on the leftmost
727 * branch of the root node (root slot 0) or in the root node itself.
728 * Non-keyrings avoid the leftmost branch of the root entirely (root
729 * slots 1-15).
730 */
731 if (!(ctx->flags & KEYRING_SEARCH_RECURSE))
732 goto not_this_keyring;
733
734 ptr = READ_ONCE(keyring->keys.root);
735 if (!ptr)
736 goto not_this_keyring;
737
738 if (assoc_array_ptr_is_shortcut(ptr)) {
739 /* If the root is a shortcut, either the keyring only contains
740 * keyring pointers (everything clusters behind root slot 0) or
741 * doesn't contain any keyring pointers.
742 */
743 shortcut = assoc_array_ptr_to_shortcut(ptr);
744 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
745 goto not_this_keyring;
746
747 ptr = READ_ONCE(shortcut->next_node);
748 node = assoc_array_ptr_to_node(ptr);
749 goto begin_node;
750 }
751
752 node = assoc_array_ptr_to_node(ptr);
753 ptr = node->slots[0];
754 if (!assoc_array_ptr_is_meta(ptr))
755 goto begin_node;
756
757descend_to_node:
758 /* Descend to a more distal node in this keyring's content tree and go
759 * through that.
760 */
761 kdebug("descend");
762 if (assoc_array_ptr_is_shortcut(ptr)) {
763 shortcut = assoc_array_ptr_to_shortcut(ptr);
764 ptr = READ_ONCE(shortcut->next_node);
765 BUG_ON(!assoc_array_ptr_is_node(ptr));
766 }
767 node = assoc_array_ptr_to_node(ptr);
768
769begin_node:
770 kdebug("begin_node");
771 slot = 0;
772ascend_to_node:
773 /* Go through the slots in a node */
774 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
775 ptr = READ_ONCE(node->slots[slot]);
776
777 if (assoc_array_ptr_is_meta(ptr)) {
778 if (node->back_pointer ||
779 assoc_array_ptr_is_shortcut(ptr))
780 goto descend_to_node;
781 }
782
783 if (!keyring_ptr_is_keyring(ptr))
784 continue;
785
786 key = keyring_ptr_to_key(ptr);
787
788 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
789 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
790 ctx->result = ERR_PTR(-ELOOP);
791 return false;
792 }
793 goto not_this_keyring;
794 }
795
796 /* Search a nested keyring */
797 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
798 key_task_permission(make_key_ref(key, ctx->possessed),
799 ctx->cred, KEY_NEED_SEARCH) < 0)
800 continue;
801
802 /* stack the current position */
803 stack[sp].keyring = keyring;
804 stack[sp].node = node;
805 stack[sp].slot = slot;
806 sp++;
807
808 /* begin again with the new keyring */
809 keyring = key;
810 goto descend_to_keyring;
811 }
812
813 /* We've dealt with all the slots in the current node, so now we need
814 * to ascend to the parent and continue processing there.
815 */
816 ptr = READ_ONCE(node->back_pointer);
817 slot = node->parent_slot;
818
819 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
820 shortcut = assoc_array_ptr_to_shortcut(ptr);
821 ptr = READ_ONCE(shortcut->back_pointer);
822 slot = shortcut->parent_slot;
823 }
824 if (!ptr)
825 goto not_this_keyring;
826 node = assoc_array_ptr_to_node(ptr);
827 slot++;
828
829 /* If we've ascended to the root (zero backpointer), we must have just
830 * finished processing the leftmost branch rather than the root slots -
831 * so there can't be any more keyrings for us to find.
832 */
833 if (node->back_pointer) {
834 kdebug("ascend %d", slot);
835 goto ascend_to_node;
836 }
837
838 /* The keyring we're looking at was disqualified or didn't contain a
839 * matching key.
840 */
841not_this_keyring:
842 kdebug("not_this_keyring %d", sp);
843 if (sp <= 0) {
844 kleave(" = false");
845 return false;
846 }
847
848 /* Resume the processing of a keyring higher up in the tree */
849 sp--;
850 keyring = stack[sp].keyring;
851 node = stack[sp].node;
852 slot = stack[sp].slot + 1;
853 kdebug("ascend to %d [%d]", keyring->serial, slot);
854 goto ascend_to_node;
855
856 /* We found a viable match */
857found:
858 key = key_ref_to_ptr(ctx->result);
859 key_check(key);
860 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
861 key->last_used_at = ctx->now;
862 keyring->last_used_at = ctx->now;
863 while (sp > 0)
864 stack[--sp].keyring->last_used_at = ctx->now;
865 }
866 kleave(" = true");
867 return true;
868}
869
870/**
871 * keyring_search_rcu - Search a keyring tree for a matching key under RCU
872 * @keyring_ref: A pointer to the keyring with possession indicator.
873 * @ctx: The keyring search context.
874 *
875 * Search the supplied keyring tree for a key that matches the criteria given.
876 * The root keyring and any linked keyrings must grant Search permission to the
877 * caller to be searchable and keys can only be found if they too grant Search
878 * to the caller. The possession flag on the root keyring pointer controls use
879 * of the possessor bits in permissions checking of the entire tree. In
880 * addition, the LSM gets to forbid keyring searches and key matches.
881 *
882 * The search is performed as a breadth-then-depth search up to the prescribed
883 * limit (KEYRING_SEARCH_MAX_DEPTH). The caller must hold the RCU read lock to
884 * prevent keyrings from being destroyed or rearranged whilst they are being
885 * searched.
886 *
887 * Keys are matched to the type provided and are then filtered by the match
888 * function, which is given the description to use in any way it sees fit. The
889 * match function may use any attributes of a key that it wishes to
890 * determine the match. Normally the match function from the key type would be
891 * used.
892 *
893 * RCU can be used to prevent the keyring key lists from disappearing without
894 * the need to take lots of locks.
895 *
896 * Returns a pointer to the found key and increments the key usage count if
897 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
898 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
899 * specified keyring wasn't a keyring.
900 *
901 * In the case of a successful return, the possession attribute from
902 * @keyring_ref is propagated to the returned key reference.
903 */
904key_ref_t keyring_search_rcu(key_ref_t keyring_ref,
905 struct keyring_search_context *ctx)
906{
907 struct key *keyring;
908 long err;
909
910 ctx->iterator = keyring_search_iterator;
911 ctx->possessed = is_key_possessed(keyring_ref);
912 ctx->result = ERR_PTR(-EAGAIN);
913
914 keyring = key_ref_to_ptr(keyring_ref);
915 key_check(keyring);
916
917 if (keyring->type != &key_type_keyring)
918 return ERR_PTR(-ENOTDIR);
919
920 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
921 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
922 if (err < 0)
923 return ERR_PTR(err);
924 }
925
926 ctx->now = ktime_get_real_seconds();
927 if (search_nested_keyrings(keyring, ctx))
928 __key_get(key_ref_to_ptr(ctx->result));
929 return ctx->result;
930}
931
932/**
933 * keyring_search - Search the supplied keyring tree for a matching key
934 * @keyring: The root of the keyring tree to be searched.
935 * @type: The type of keyring we want to find.
936 * @description: The name of the keyring we want to find.
937 * @recurse: True to search the children of @keyring also
938 *
939 * As keyring_search_rcu() above, but using the current task's credentials and
940 * type's default matching function and preferred search method.
941 */
942key_ref_t keyring_search(key_ref_t keyring,
943 struct key_type *type,
944 const char *description,
945 bool recurse)
946{
947 struct keyring_search_context ctx = {
948 .index_key.type = type,
949 .index_key.description = description,
950 .index_key.desc_len = strlen(description),
951 .cred = current_cred(),
952 .match_data.cmp = key_default_cmp,
953 .match_data.raw_data = description,
954 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
955 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
956 };
957 key_ref_t key;
958 int ret;
959
960 if (recurse)
961 ctx.flags |= KEYRING_SEARCH_RECURSE;
962 if (type->match_preparse) {
963 ret = type->match_preparse(&ctx.match_data);
964 if (ret < 0)
965 return ERR_PTR(ret);
966 }
967
968 rcu_read_lock();
969 key = keyring_search_rcu(keyring, &ctx);
970 rcu_read_unlock();
971
972 if (type->match_free)
973 type->match_free(&ctx.match_data);
974 return key;
975}
976EXPORT_SYMBOL(keyring_search);
977
978static struct key_restriction *keyring_restriction_alloc(
979 key_restrict_link_func_t check)
980{
981 struct key_restriction *keyres =
982 kzalloc_obj(struct key_restriction);
983
984 if (!keyres)
985 return ERR_PTR(-ENOMEM);
986
987 keyres->check = check;
988
989 return keyres;
990}
991
992/*
993 * Semaphore to serialise restriction setup to prevent reference count
994 * cycles through restriction key pointers.
995 */
996static DECLARE_RWSEM(keyring_serialise_restrict_sem);
997
998/*
999 * Check for restriction cycles that would prevent keyring garbage collection.
1000 * keyring_serialise_restrict_sem must be held.
1001 */
1002static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
1003 struct key_restriction *keyres)
1004{
1005 while (keyres && keyres->key &&
1006 keyres->key->type == &key_type_keyring) {
1007 if (keyres->key == dest_keyring)
1008 return true;
1009
1010 keyres = keyres->key->restrict_link;
1011 }
1012
1013 return false;
1014}
1015
1016/**
1017 * keyring_restrict - Look up and apply a restriction to a keyring
1018 * @keyring_ref: The keyring to be restricted
1019 * @type: The key type that will provide the restriction checker.
1020 * @restriction: The restriction options to apply to the keyring
1021 *
1022 * Look up a keyring and apply a restriction to it. The restriction is managed
1023 * by the specific key type, but can be configured by the options specified in
1024 * the restriction string.
1025 */
1026int keyring_restrict(key_ref_t keyring_ref, const char *type,
1027 const char *restriction)
1028{
1029 struct key *keyring;
1030 struct key_type *restrict_type = NULL;
1031 struct key_restriction *restrict_link;
1032 int ret = 0;
1033
1034 keyring = key_ref_to_ptr(keyring_ref);
1035 key_check(keyring);
1036
1037 if (keyring->type != &key_type_keyring)
1038 return -ENOTDIR;
1039
1040 if (!type) {
1041 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1042 } else {
1043 restrict_type = key_type_lookup(type);
1044
1045 if (IS_ERR(restrict_type))
1046 return PTR_ERR(restrict_type);
1047
1048 if (!restrict_type->lookup_restriction) {
1049 ret = -ENOENT;
1050 goto error;
1051 }
1052
1053 restrict_link = restrict_type->lookup_restriction(restriction);
1054 }
1055
1056 if (IS_ERR(restrict_link)) {
1057 ret = PTR_ERR(restrict_link);
1058 goto error;
1059 }
1060
1061 down_write(&keyring->sem);
1062 down_write(&keyring_serialise_restrict_sem);
1063
1064 if (keyring->restrict_link) {
1065 ret = -EEXIST;
1066 } else if (keyring_detect_restriction_cycle(keyring, restrict_link)) {
1067 ret = -EDEADLK;
1068 } else {
1069 keyring->restrict_link = restrict_link;
1070 notify_key(keyring, NOTIFY_KEY_SETATTR, 0);
1071 }
1072
1073 up_write(&keyring_serialise_restrict_sem);
1074 up_write(&keyring->sem);
1075
1076 if (ret < 0) {
1077 key_put(restrict_link->key);
1078 kfree(restrict_link);
1079 }
1080
1081error:
1082 if (restrict_type)
1083 key_type_put(restrict_type);
1084
1085 return ret;
1086}
1087EXPORT_SYMBOL(keyring_restrict);
1088
1089/*
1090 * Search the given keyring for a key that might be updated.
1091 *
1092 * The caller must guarantee that the keyring is a keyring and that the
1093 * permission is granted to modify the keyring as no check is made here. The
1094 * caller must also hold a lock on the keyring semaphore.
1095 *
1096 * Returns a pointer to the found key with usage count incremented if
1097 * successful and returns NULL if not found. Revoked and invalidated keys are
1098 * skipped over.
1099 *
1100 * If successful, the possession indicator is propagated from the keyring ref
1101 * to the returned key reference.
1102 */
1103key_ref_t find_key_to_update(key_ref_t keyring_ref,
1104 const struct keyring_index_key *index_key)
1105{
1106 struct key *keyring, *key;
1107 const void *object;
1108
1109 keyring = key_ref_to_ptr(keyring_ref);
1110
1111 kenter("{%d},{%s,%s}",
1112 keyring->serial, index_key->type->name, index_key->description);
1113
1114 guard(rcu)();
1115 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1116 index_key);
1117
1118 if (object)
1119 goto found;
1120
1121 kleave(" = NULL");
1122 return NULL;
1123
1124found:
1125 key = keyring_ptr_to_key(object);
1126 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1127 (1 << KEY_FLAG_REVOKED))) {
1128 kleave(" = NULL [x]");
1129 return NULL;
1130 }
1131 __key_get(key);
1132 kleave(" = {%d}", key->serial);
1133 return make_key_ref(key, is_key_possessed(keyring_ref));
1134}
1135
1136/*
1137 * Find a keyring with the specified name.
1138 *
1139 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1140 * user in the current user namespace are considered. If @uid_keyring is %true,
1141 * the keyring additionally must have been allocated as a user or user session
1142 * keyring; otherwise, it must grant Search permission directly to the caller.
1143 *
1144 * Returns a pointer to the keyring with the keyring's refcount having being
1145 * incremented on success. -ENOKEY is returned if a key could not be found.
1146 */
1147struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1148{
1149 struct user_namespace *ns = current_user_ns();
1150 struct key *keyring;
1151
1152 if (!name)
1153 return ERR_PTR(-EINVAL);
1154
1155 read_lock(&keyring_name_lock);
1156
1157 /* Search this hash bucket for a keyring with a matching name that
1158 * grants Search permission and that hasn't been revoked
1159 */
1160 list_for_each_entry(keyring, &ns->keyring_name_list, name_link) {
1161 if (!kuid_has_mapping(ns, keyring->user->uid))
1162 continue;
1163
1164 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1165 continue;
1166
1167 if (strcmp(keyring->description, name) != 0)
1168 continue;
1169
1170 if (uid_keyring) {
1171 if (!test_bit(KEY_FLAG_UID_KEYRING,
1172 &keyring->flags))
1173 continue;
1174 } else {
1175 if (key_permission(make_key_ref(keyring, 0),
1176 KEY_NEED_SEARCH) < 0)
1177 continue;
1178 }
1179
1180 /* we've got a match but we might end up racing with
1181 * key_cleanup() if the keyring is currently 'dead'
1182 * (ie. it has a zero usage count) */
1183 if (!refcount_inc_not_zero(&keyring->usage))
1184 continue;
1185 keyring->last_used_at = ktime_get_real_seconds();
1186 goto out;
1187 }
1188
1189 keyring = ERR_PTR(-ENOKEY);
1190out:
1191 read_unlock(&keyring_name_lock);
1192 return keyring;
1193}
1194
1195static int keyring_detect_cycle_iterator(const void *object,
1196 void *iterator_data)
1197{
1198 struct keyring_search_context *ctx = iterator_data;
1199 const struct key *key = keyring_ptr_to_key(object);
1200
1201 kenter("{%d}", key->serial);
1202
1203 /* We might get a keyring with matching index-key that is nonetheless a
1204 * different keyring. */
1205 if (key != ctx->match_data.raw_data)
1206 return 0;
1207
1208 ctx->result = ERR_PTR(-EDEADLK);
1209 return 1;
1210}
1211
1212/*
1213 * See if a cycle will be created by inserting acyclic tree B in acyclic
1214 * tree A at the topmost level (ie: as a direct child of A).
1215 *
1216 * Since we are adding B to A at the top level, checking for cycles should just
1217 * be a matter of seeing if node A is somewhere in tree B.
1218 */
1219static int keyring_detect_cycle(struct key *A, struct key *B)
1220{
1221 struct keyring_search_context ctx = {
1222 .index_key = A->index_key,
1223 .match_data.raw_data = A,
1224 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1225 .iterator = keyring_detect_cycle_iterator,
1226 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1227 KEYRING_SEARCH_NO_UPDATE_TIME |
1228 KEYRING_SEARCH_NO_CHECK_PERM |
1229 KEYRING_SEARCH_DETECT_TOO_DEEP |
1230 KEYRING_SEARCH_RECURSE),
1231 };
1232
1233 rcu_read_lock();
1234 search_nested_keyrings(B, &ctx);
1235 rcu_read_unlock();
1236 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1237}
1238
1239/*
1240 * Lock keyring for link.
1241 */
1242int __key_link_lock(struct key *keyring,
1243 const struct keyring_index_key *index_key)
1244 __acquires(&keyring->sem)
1245 __acquires(&keyring_serialise_link_lock)
1246{
1247 if (keyring->type != &key_type_keyring)
1248 return -ENOTDIR;
1249
1250 down_write(&keyring->sem);
1251
1252 /* Serialise link/link calls to prevent parallel calls causing a cycle
1253 * when linking two keyring in opposite orders.
1254 */
1255 if (index_key->type == &key_type_keyring)
1256 mutex_lock(&keyring_serialise_link_lock);
1257
1258 return 0;
1259}
1260
1261/*
1262 * Lock keyrings for move (link/unlink combination).
1263 */
1264int __key_move_lock(struct key *l_keyring, struct key *u_keyring,
1265 const struct keyring_index_key *index_key)
1266 __acquires(&l_keyring->sem)
1267 __acquires(&u_keyring->sem)
1268 __acquires(&keyring_serialise_link_lock)
1269{
1270 if (l_keyring->type != &key_type_keyring ||
1271 u_keyring->type != &key_type_keyring)
1272 return -ENOTDIR;
1273
1274 /* We have to be very careful here to take the keyring locks in the
1275 * right order, lest we open ourselves to deadlocking against another
1276 * move operation.
1277 */
1278 if (l_keyring < u_keyring) {
1279 down_write(&l_keyring->sem);
1280 down_write_nested(&u_keyring->sem, 1);
1281 } else {
1282 down_write(&u_keyring->sem);
1283 down_write_nested(&l_keyring->sem, 1);
1284 }
1285
1286 /* Serialise link/link calls to prevent parallel calls causing a cycle
1287 * when linking two keyring in opposite orders.
1288 */
1289 if (index_key->type == &key_type_keyring)
1290 mutex_lock(&keyring_serialise_link_lock);
1291
1292 return 0;
1293}
1294
1295/*
1296 * Preallocate memory so that a key can be linked into to a keyring.
1297 */
1298int __key_link_begin(struct key *keyring,
1299 const struct keyring_index_key *index_key,
1300 struct assoc_array_edit **_edit)
1301{
1302 struct assoc_array_edit *edit;
1303 int ret;
1304
1305 kenter("%d,%s,%s,",
1306 keyring->serial, index_key->type->name, index_key->description);
1307
1308 BUG_ON(index_key->desc_len == 0);
1309 BUG_ON(*_edit != NULL);
1310
1311 *_edit = NULL;
1312
1313 ret = -EKEYREVOKED;
1314 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1315 goto error;
1316
1317 /* Create an edit script that will insert/replace the key in the
1318 * keyring tree.
1319 */
1320 edit = assoc_array_insert(&keyring->keys,
1321 &keyring_assoc_array_ops,
1322 index_key,
1323 NULL);
1324 if (IS_ERR(edit)) {
1325 ret = PTR_ERR(edit);
1326 goto error;
1327 }
1328
1329 /* If we're not replacing a link in-place then we're going to need some
1330 * extra quota.
1331 */
1332 if (!edit->dead_leaf) {
1333 ret = key_payload_reserve(keyring,
1334 keyring->datalen + KEYQUOTA_LINK_BYTES);
1335 if (ret < 0)
1336 goto error_cancel;
1337 }
1338
1339 *_edit = edit;
1340 kleave(" = 0");
1341 return 0;
1342
1343error_cancel:
1344 assoc_array_cancel_edit(edit);
1345error:
1346 kleave(" = %d", ret);
1347 return ret;
1348}
1349
1350/*
1351 * Check already instantiated keys aren't going to be a problem.
1352 *
1353 * The caller must have called __key_link_begin(). Don't need to call this for
1354 * keys that were created since __key_link_begin() was called.
1355 */
1356int __key_link_check_live_key(struct key *keyring, struct key *key)
1357{
1358 if (key->type == &key_type_keyring)
1359 /* check that we aren't going to create a cycle by linking one
1360 * keyring to another */
1361 return keyring_detect_cycle(keyring, key);
1362 return 0;
1363}
1364
1365/*
1366 * Link a key into to a keyring.
1367 *
1368 * Must be called with __key_link_begin() having being called. Discards any
1369 * already extant link to matching key if there is one, so that each keyring
1370 * holds at most one link to any given key of a particular type+description
1371 * combination.
1372 */
1373void __key_link(struct key *keyring, struct key *key,
1374 struct assoc_array_edit **_edit)
1375{
1376 __key_get(key);
1377 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1378 assoc_array_apply_edit(*_edit);
1379 *_edit = NULL;
1380 notify_key(keyring, NOTIFY_KEY_LINKED, key_serial(key));
1381}
1382
1383/*
1384 * Finish linking a key into to a keyring.
1385 *
1386 * Must be called with __key_link_begin() having being called.
1387 */
1388void __key_link_end(struct key *keyring,
1389 const struct keyring_index_key *index_key,
1390 struct assoc_array_edit *edit)
1391 __releases(&keyring->sem)
1392 __releases(&keyring_serialise_link_lock)
1393{
1394 BUG_ON(index_key->type == NULL);
1395 kenter("%d,%s,", keyring->serial, index_key->type->name);
1396
1397 if (edit) {
1398 if (!edit->dead_leaf) {
1399 key_payload_reserve(keyring,
1400 keyring->datalen - KEYQUOTA_LINK_BYTES);
1401 }
1402 assoc_array_cancel_edit(edit);
1403 }
1404 up_write(&keyring->sem);
1405
1406 if (index_key->type == &key_type_keyring)
1407 mutex_unlock(&keyring_serialise_link_lock);
1408}
1409
1410/*
1411 * Check addition of keys to restricted keyrings.
1412 */
1413static int __key_link_check_restriction(struct key *keyring, struct key *key)
1414{
1415 if (!keyring->restrict_link || !keyring->restrict_link->check)
1416 return 0;
1417 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1418 keyring->restrict_link->key);
1419}
1420
1421/**
1422 * key_link - Link a key to a keyring
1423 * @keyring: The keyring to make the link in.
1424 * @key: The key to link to.
1425 *
1426 * Make a link in a keyring to a key, such that the keyring holds a reference
1427 * on that key and the key can potentially be found by searching that keyring.
1428 *
1429 * This function will write-lock the keyring's semaphore and will consume some
1430 * of the user's key data quota to hold the link.
1431 *
1432 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1433 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1434 * full, -EDQUOT if there is insufficient key data quota remaining to add
1435 * another link or -ENOMEM if there's insufficient memory.
1436 *
1437 * It is assumed that the caller has checked that it is permitted for a link to
1438 * be made (the keyring should have Write permission and the key Link
1439 * permission).
1440 */
1441int key_link(struct key *keyring, struct key *key)
1442{
1443 struct assoc_array_edit *edit = NULL;
1444 int ret;
1445
1446 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1447
1448 key_check(keyring);
1449 key_check(key);
1450
1451 ret = __key_link_lock(keyring, &key->index_key);
1452 if (ret < 0)
1453 goto error;
1454
1455 ret = __key_link_begin(keyring, &key->index_key, &edit);
1456 if (ret < 0)
1457 goto error_end;
1458
1459 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1460 ret = __key_link_check_restriction(keyring, key);
1461 if (ret == 0)
1462 ret = __key_link_check_live_key(keyring, key);
1463 if (ret == 0)
1464 __key_link(keyring, key, &edit);
1465
1466error_end:
1467 __key_link_end(keyring, &key->index_key, edit);
1468error:
1469 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1470 return ret;
1471}
1472EXPORT_SYMBOL(key_link);
1473
1474/*
1475 * Lock a keyring for unlink.
1476 */
1477static int __key_unlink_lock(struct key *keyring)
1478 __acquires(&keyring->sem)
1479{
1480 if (keyring->type != &key_type_keyring)
1481 return -ENOTDIR;
1482
1483 down_write(&keyring->sem);
1484 return 0;
1485}
1486
1487/*
1488 * Begin the process of unlinking a key from a keyring.
1489 */
1490static int __key_unlink_begin(struct key *keyring, struct key *key,
1491 struct assoc_array_edit **_edit)
1492{
1493 struct assoc_array_edit *edit;
1494
1495 BUG_ON(*_edit != NULL);
1496
1497 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1498 &key->index_key);
1499 if (IS_ERR(edit))
1500 return PTR_ERR(edit);
1501
1502 if (!edit)
1503 return -ENOENT;
1504
1505 *_edit = edit;
1506 return 0;
1507}
1508
1509/*
1510 * Apply an unlink change.
1511 */
1512static void __key_unlink(struct key *keyring, struct key *key,
1513 struct assoc_array_edit **_edit)
1514{
1515 assoc_array_apply_edit(*_edit);
1516 notify_key(keyring, NOTIFY_KEY_UNLINKED, key_serial(key));
1517 *_edit = NULL;
1518 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1519}
1520
1521/*
1522 * Finish unlinking a key from to a keyring.
1523 */
1524static void __key_unlink_end(struct key *keyring,
1525 struct key *key,
1526 struct assoc_array_edit *edit)
1527 __releases(&keyring->sem)
1528{
1529 if (edit)
1530 assoc_array_cancel_edit(edit);
1531 up_write(&keyring->sem);
1532}
1533
1534/**
1535 * key_unlink - Unlink the first link to a key from a keyring.
1536 * @keyring: The keyring to remove the link from.
1537 * @key: The key the link is to.
1538 *
1539 * Remove a link from a keyring to a key.
1540 *
1541 * This function will write-lock the keyring's semaphore.
1542 *
1543 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1544 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1545 * memory.
1546 *
1547 * It is assumed that the caller has checked that it is permitted for a link to
1548 * be removed (the keyring should have Write permission; no permissions are
1549 * required on the key).
1550 */
1551int key_unlink(struct key *keyring, struct key *key)
1552{
1553 struct assoc_array_edit *edit = NULL;
1554 int ret;
1555
1556 key_check(keyring);
1557 key_check(key);
1558
1559 ret = __key_unlink_lock(keyring);
1560 if (ret < 0)
1561 return ret;
1562
1563 ret = __key_unlink_begin(keyring, key, &edit);
1564 if (ret == 0)
1565 __key_unlink(keyring, key, &edit);
1566 __key_unlink_end(keyring, key, edit);
1567 return ret;
1568}
1569EXPORT_SYMBOL(key_unlink);
1570
1571/**
1572 * key_move - Move a key from one keyring to another
1573 * @key: The key to move
1574 * @from_keyring: The keyring to remove the link from.
1575 * @to_keyring: The keyring to make the link in.
1576 * @flags: Qualifying flags, such as KEYCTL_MOVE_EXCL.
1577 *
1578 * Make a link in @to_keyring to a key, such that the keyring holds a reference
1579 * on that key and the key can potentially be found by searching that keyring
1580 * whilst simultaneously removing a link to the key from @from_keyring.
1581 *
1582 * This function will write-lock both keyring's semaphores and will consume
1583 * some of the user's key data quota to hold the link on @to_keyring.
1584 *
1585 * Returns 0 if successful, -ENOTDIR if either keyring isn't a keyring,
1586 * -EKEYREVOKED if either keyring has been revoked, -ENFILE if the second
1587 * keyring is full, -EDQUOT if there is insufficient key data quota remaining
1588 * to add another link or -ENOMEM if there's insufficient memory. If
1589 * KEYCTL_MOVE_EXCL is set, then -EEXIST will be returned if there's already a
1590 * matching key in @to_keyring.
1591 *
1592 * It is assumed that the caller has checked that it is permitted for a link to
1593 * be made (the keyring should have Write permission and the key Link
1594 * permission).
1595 */
1596int key_move(struct key *key,
1597 struct key *from_keyring,
1598 struct key *to_keyring,
1599 unsigned int flags)
1600{
1601 struct assoc_array_edit *from_edit = NULL, *to_edit = NULL;
1602 int ret;
1603
1604 kenter("%d,%d,%d", key->serial, from_keyring->serial, to_keyring->serial);
1605
1606 if (from_keyring == to_keyring)
1607 return 0;
1608
1609 key_check(key);
1610 key_check(from_keyring);
1611 key_check(to_keyring);
1612
1613 ret = __key_move_lock(from_keyring, to_keyring, &key->index_key);
1614 if (ret < 0)
1615 goto out;
1616 ret = __key_unlink_begin(from_keyring, key, &from_edit);
1617 if (ret < 0)
1618 goto error;
1619 ret = __key_link_begin(to_keyring, &key->index_key, &to_edit);
1620 if (ret < 0)
1621 goto error;
1622
1623 ret = -EEXIST;
1624 if (to_edit->dead_leaf && (flags & KEYCTL_MOVE_EXCL))
1625 goto error;
1626
1627 ret = __key_link_check_restriction(to_keyring, key);
1628 if (ret < 0)
1629 goto error;
1630 ret = __key_link_check_live_key(to_keyring, key);
1631 if (ret < 0)
1632 goto error;
1633
1634 __key_unlink(from_keyring, key, &from_edit);
1635 __key_link(to_keyring, key, &to_edit);
1636error:
1637 __key_link_end(to_keyring, &key->index_key, to_edit);
1638 __key_unlink_end(from_keyring, key, from_edit);
1639out:
1640 kleave(" = %d", ret);
1641 return ret;
1642}
1643EXPORT_SYMBOL(key_move);
1644
1645/**
1646 * keyring_clear - Clear a keyring
1647 * @keyring: The keyring to clear.
1648 *
1649 * Clear the contents of the specified keyring.
1650 *
1651 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1652 */
1653int keyring_clear(struct key *keyring)
1654{
1655 struct assoc_array_edit *edit;
1656 int ret;
1657
1658 if (keyring->type != &key_type_keyring)
1659 return -ENOTDIR;
1660
1661 down_write(&keyring->sem);
1662
1663 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1664 if (IS_ERR(edit)) {
1665 ret = PTR_ERR(edit);
1666 } else {
1667 if (edit)
1668 assoc_array_apply_edit(edit);
1669 notify_key(keyring, NOTIFY_KEY_CLEARED, 0);
1670 key_payload_reserve(keyring, 0);
1671 ret = 0;
1672 }
1673
1674 up_write(&keyring->sem);
1675 return ret;
1676}
1677EXPORT_SYMBOL(keyring_clear);
1678
1679/*
1680 * Dispose of the links from a revoked keyring.
1681 *
1682 * This is called with the key sem write-locked.
1683 */
1684static void keyring_revoke(struct key *keyring)
1685{
1686 struct assoc_array_edit *edit;
1687
1688 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1689 if (!IS_ERR(edit)) {
1690 if (edit)
1691 assoc_array_apply_edit(edit);
1692 key_payload_reserve(keyring, 0);
1693 }
1694}
1695
1696static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1697{
1698 struct key *key = keyring_ptr_to_key(object);
1699 time64_t *limit = iterator_data;
1700
1701 if (key_is_dead(key, *limit))
1702 return false;
1703 key_get(key);
1704 return true;
1705}
1706
1707static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1708{
1709 const struct key *key = keyring_ptr_to_key(object);
1710 time64_t *limit = iterator_data;
1711
1712 key_check(key);
1713 return key_is_dead(key, *limit);
1714}
1715
1716/*
1717 * Garbage collect pointers from a keyring.
1718 *
1719 * Not called with any locks held. The keyring's key struct will not be
1720 * deallocated under us as only our caller may deallocate it.
1721 */
1722void keyring_gc(struct key *keyring, time64_t limit)
1723{
1724 int result;
1725
1726 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1727
1728 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1729 (1 << KEY_FLAG_REVOKED)))
1730 goto dont_gc;
1731
1732 /* scan the keyring looking for dead keys */
1733 rcu_read_lock();
1734 result = assoc_array_iterate(&keyring->keys,
1735 keyring_gc_check_iterator, &limit);
1736 rcu_read_unlock();
1737 if (result == true)
1738 goto do_gc;
1739
1740dont_gc:
1741 kleave(" [no gc]");
1742 return;
1743
1744do_gc:
1745 down_write(&keyring->sem);
1746 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1747 keyring_gc_select_iterator, &limit);
1748 up_write(&keyring->sem);
1749 kleave(" [gc]");
1750}
1751
1752/*
1753 * Garbage collect restriction pointers from a keyring.
1754 *
1755 * Keyring restrictions are associated with a key type, and must be cleaned
1756 * up if the key type is unregistered. The restriction is altered to always
1757 * reject additional keys so a keyring cannot be opened up by unregistering
1758 * a key type.
1759 *
1760 * Not called with any keyring locks held. The keyring's key struct will not
1761 * be deallocated under us as only our caller may deallocate it.
1762 *
1763 * The caller is required to hold key_types_sem and dead_type->sem. This is
1764 * fulfilled by key_gc_keytype() holding the locks on behalf of
1765 * key_garbage_collector(), which it invokes on a workqueue.
1766 */
1767void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1768{
1769 struct key_restriction *keyres;
1770
1771 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1772
1773 /*
1774 * keyring->restrict_link is only assigned at key allocation time
1775 * or with the key type locked, so the only values that could be
1776 * concurrently assigned to keyring->restrict_link are for key
1777 * types other than dead_type. Given this, it's ok to check
1778 * the key type before acquiring keyring->sem.
1779 */
1780 if (!dead_type || !keyring->restrict_link ||
1781 keyring->restrict_link->keytype != dead_type) {
1782 kleave(" [no restriction gc]");
1783 return;
1784 }
1785
1786 /* Lock the keyring to ensure that a link is not in progress */
1787 down_write(&keyring->sem);
1788
1789 keyres = keyring->restrict_link;
1790
1791 keyres->check = restrict_link_reject;
1792
1793 key_put(keyres->key);
1794 keyres->key = NULL;
1795 keyres->keytype = NULL;
1796
1797 up_write(&keyring->sem);
1798
1799 kleave(" [restriction gc]");
1800}