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