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