Loading...
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_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 .instantiate = keyring_instantiate,
88 .match = user_match,
89 .revoke = keyring_revoke,
90 .destroy = keyring_destroy,
91 .describe = keyring_describe,
92 .read = keyring_read,
93};
94EXPORT_SYMBOL(key_type_keyring);
95
96/*
97 * Semaphore to serialise link/link calls to prevent two link calls in parallel
98 * introducing a cycle.
99 */
100static DECLARE_RWSEM(keyring_serialise_link_sem);
101
102/*
103 * Publish the name of a keyring so that it can be found by name (if it has
104 * one).
105 */
106static void keyring_publish_name(struct key *keyring)
107{
108 int bucket;
109
110 if (keyring->description) {
111 bucket = keyring_hash(keyring->description);
112
113 write_lock(&keyring_name_lock);
114
115 if (!keyring_name_hash[bucket].next)
116 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
117
118 list_add_tail(&keyring->type_data.link,
119 &keyring_name_hash[bucket]);
120
121 write_unlock(&keyring_name_lock);
122 }
123}
124
125/*
126 * Initialise a keyring.
127 *
128 * Returns 0 on success, -EINVAL if given any data.
129 */
130static int keyring_instantiate(struct key *keyring,
131 struct key_preparsed_payload *prep)
132{
133 int ret;
134
135 ret = -EINVAL;
136 if (prep->datalen == 0) {
137 assoc_array_init(&keyring->keys);
138 /* make the keyring available by name if it has one */
139 keyring_publish_name(keyring);
140 ret = 0;
141 }
142
143 return ret;
144}
145
146/*
147 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
148 * fold the carry back too, but that requires inline asm.
149 */
150static u64 mult_64x32_and_fold(u64 x, u32 y)
151{
152 u64 hi = (u64)(u32)(x >> 32) * y;
153 u64 lo = (u64)(u32)(x) * y;
154 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
155}
156
157/*
158 * Hash a key type and description.
159 */
160static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key)
161{
162 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
163 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
164 const char *description = index_key->description;
165 unsigned long hash, type;
166 u32 piece;
167 u64 acc;
168 int n, desc_len = index_key->desc_len;
169
170 type = (unsigned long)index_key->type;
171
172 acc = mult_64x32_and_fold(type, desc_len + 13);
173 acc = mult_64x32_and_fold(acc, 9207);
174 for (;;) {
175 n = desc_len;
176 if (n <= 0)
177 break;
178 if (n > 4)
179 n = 4;
180 piece = 0;
181 memcpy(&piece, description, n);
182 description += n;
183 desc_len -= n;
184 acc = mult_64x32_and_fold(acc, piece);
185 acc = mult_64x32_and_fold(acc, 9207);
186 }
187
188 /* Fold the hash down to 32 bits if need be. */
189 hash = acc;
190 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
191 hash ^= acc >> 32;
192
193 /* Squidge all the keyrings into a separate part of the tree to
194 * ordinary keys by making sure the lowest level segment in the hash is
195 * zero for keyrings and non-zero otherwise.
196 */
197 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
198 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
199 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
200 return (hash + (hash << level_shift)) & ~fan_mask;
201 return hash;
202}
203
204/*
205 * Build the next index key chunk.
206 *
207 * On 32-bit systems the index key is laid out as:
208 *
209 * 0 4 5 9...
210 * hash desclen typeptr desc[]
211 *
212 * On 64-bit systems:
213 *
214 * 0 8 9 17...
215 * hash desclen typeptr desc[]
216 *
217 * We return it one word-sized chunk at a time.
218 */
219static unsigned long keyring_get_key_chunk(const void *data, int level)
220{
221 const struct keyring_index_key *index_key = data;
222 unsigned long chunk = 0;
223 long offset = 0;
224 int desc_len = index_key->desc_len, n = sizeof(chunk);
225
226 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
227 switch (level) {
228 case 0:
229 return hash_key_type_and_desc(index_key);
230 case 1:
231 return ((unsigned long)index_key->type << 8) | desc_len;
232 case 2:
233 if (desc_len == 0)
234 return (u8)((unsigned long)index_key->type >>
235 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
236 n--;
237 offset = 1;
238 default:
239 offset += sizeof(chunk) - 1;
240 offset += (level - 3) * sizeof(chunk);
241 if (offset >= desc_len)
242 return 0;
243 desc_len -= offset;
244 if (desc_len > n)
245 desc_len = n;
246 offset += desc_len;
247 do {
248 chunk <<= 8;
249 chunk |= ((u8*)index_key->description)[--offset];
250 } while (--desc_len > 0);
251
252 if (level == 2) {
253 chunk <<= 8;
254 chunk |= (u8)((unsigned long)index_key->type >>
255 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
256 }
257 return chunk;
258 }
259}
260
261static unsigned long keyring_get_object_key_chunk(const void *object, int level)
262{
263 const struct key *key = keyring_ptr_to_key(object);
264 return keyring_get_key_chunk(&key->index_key, level);
265}
266
267static bool keyring_compare_object(const void *object, const void *data)
268{
269 const struct keyring_index_key *index_key = data;
270 const struct key *key = keyring_ptr_to_key(object);
271
272 return key->index_key.type == index_key->type &&
273 key->index_key.desc_len == index_key->desc_len &&
274 memcmp(key->index_key.description, index_key->description,
275 index_key->desc_len) == 0;
276}
277
278/*
279 * Compare the index keys of a pair of objects and determine the bit position
280 * at which they differ - if they differ.
281 */
282static int keyring_diff_objects(const void *object, const void *data)
283{
284 const struct key *key_a = keyring_ptr_to_key(object);
285 const struct keyring_index_key *a = &key_a->index_key;
286 const struct keyring_index_key *b = data;
287 unsigned long seg_a, seg_b;
288 int level, i;
289
290 level = 0;
291 seg_a = hash_key_type_and_desc(a);
292 seg_b = hash_key_type_and_desc(b);
293 if ((seg_a ^ seg_b) != 0)
294 goto differ;
295
296 /* The number of bits contributed by the hash is controlled by a
297 * constant in the assoc_array headers. Everything else thereafter we
298 * can deal with as being machine word-size dependent.
299 */
300 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
301 seg_a = a->desc_len;
302 seg_b = b->desc_len;
303 if ((seg_a ^ seg_b) != 0)
304 goto differ;
305
306 /* The next bit may not work on big endian */
307 level++;
308 seg_a = (unsigned long)a->type;
309 seg_b = (unsigned long)b->type;
310 if ((seg_a ^ seg_b) != 0)
311 goto differ;
312
313 level += sizeof(unsigned long);
314 if (a->desc_len == 0)
315 goto same;
316
317 i = 0;
318 if (((unsigned long)a->description | (unsigned long)b->description) &
319 (sizeof(unsigned long) - 1)) {
320 do {
321 seg_a = *(unsigned long *)(a->description + i);
322 seg_b = *(unsigned long *)(b->description + i);
323 if ((seg_a ^ seg_b) != 0)
324 goto differ_plus_i;
325 i += sizeof(unsigned long);
326 } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
327 }
328
329 for (; i < a->desc_len; i++) {
330 seg_a = *(unsigned char *)(a->description + i);
331 seg_b = *(unsigned char *)(b->description + i);
332 if ((seg_a ^ seg_b) != 0)
333 goto differ_plus_i;
334 }
335
336same:
337 return -1;
338
339differ_plus_i:
340 level += i;
341differ:
342 i = level * 8 + __ffs(seg_a ^ seg_b);
343 return i;
344}
345
346/*
347 * Free an object after stripping the keyring flag off of the pointer.
348 */
349static void keyring_free_object(void *object)
350{
351 key_put(keyring_ptr_to_key(object));
352}
353
354/*
355 * Operations for keyring management by the index-tree routines.
356 */
357static const struct assoc_array_ops keyring_assoc_array_ops = {
358 .get_key_chunk = keyring_get_key_chunk,
359 .get_object_key_chunk = keyring_get_object_key_chunk,
360 .compare_object = keyring_compare_object,
361 .diff_objects = keyring_diff_objects,
362 .free_object = keyring_free_object,
363};
364
365/*
366 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
367 * and dispose of its data.
368 *
369 * The garbage collector detects the final key_put(), removes the keyring from
370 * the serial number tree and then does RCU synchronisation before coming here,
371 * so we shouldn't need to worry about code poking around here with the RCU
372 * readlock held by this time.
373 */
374static void keyring_destroy(struct key *keyring)
375{
376 if (keyring->description) {
377 write_lock(&keyring_name_lock);
378
379 if (keyring->type_data.link.next != NULL &&
380 !list_empty(&keyring->type_data.link))
381 list_del(&keyring->type_data.link);
382
383 write_unlock(&keyring_name_lock);
384 }
385
386 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
387}
388
389/*
390 * Describe a keyring for /proc.
391 */
392static void keyring_describe(const struct key *keyring, struct seq_file *m)
393{
394 if (keyring->description)
395 seq_puts(m, keyring->description);
396 else
397 seq_puts(m, "[anon]");
398
399 if (key_is_instantiated(keyring)) {
400 if (keyring->keys.nr_leaves_on_tree != 0)
401 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
402 else
403 seq_puts(m, ": empty");
404 }
405}
406
407struct keyring_read_iterator_context {
408 size_t qty;
409 size_t count;
410 key_serial_t __user *buffer;
411};
412
413static int keyring_read_iterator(const void *object, void *data)
414{
415 struct keyring_read_iterator_context *ctx = data;
416 const struct key *key = keyring_ptr_to_key(object);
417 int ret;
418
419 kenter("{%s,%d},,{%zu/%zu}",
420 key->type->name, key->serial, ctx->count, ctx->qty);
421
422 if (ctx->count >= ctx->qty)
423 return 1;
424
425 ret = put_user(key->serial, ctx->buffer);
426 if (ret < 0)
427 return ret;
428 ctx->buffer++;
429 ctx->count += sizeof(key->serial);
430 return 0;
431}
432
433/*
434 * Read a list of key IDs from the keyring's contents in binary form
435 *
436 * The keyring's semaphore is read-locked by the caller. This prevents someone
437 * from modifying it under us - which could cause us to read key IDs multiple
438 * times.
439 */
440static long keyring_read(const struct key *keyring,
441 char __user *buffer, size_t buflen)
442{
443 struct keyring_read_iterator_context ctx;
444 unsigned long nr_keys;
445 int ret;
446
447 kenter("{%d},,%zu", key_serial(keyring), buflen);
448
449 if (buflen & (sizeof(key_serial_t) - 1))
450 return -EINVAL;
451
452 nr_keys = keyring->keys.nr_leaves_on_tree;
453 if (nr_keys == 0)
454 return 0;
455
456 /* Calculate how much data we could return */
457 ctx.qty = nr_keys * sizeof(key_serial_t);
458
459 if (!buffer || !buflen)
460 return ctx.qty;
461
462 if (buflen > ctx.qty)
463 ctx.qty = buflen;
464
465 /* Copy the IDs of the subscribed keys into the buffer */
466 ctx.buffer = (key_serial_t __user *)buffer;
467 ctx.count = 0;
468 ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
469 if (ret < 0) {
470 kleave(" = %d [iterate]", ret);
471 return ret;
472 }
473
474 kleave(" = %zu [ok]", ctx.count);
475 return ctx.count;
476}
477
478/*
479 * Allocate a keyring and link into the destination keyring.
480 */
481struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
482 const struct cred *cred, key_perm_t perm,
483 unsigned long flags, struct key *dest)
484{
485 struct key *keyring;
486 int ret;
487
488 keyring = key_alloc(&key_type_keyring, description,
489 uid, gid, cred, perm, flags);
490 if (!IS_ERR(keyring)) {
491 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
492 if (ret < 0) {
493 key_put(keyring);
494 keyring = ERR_PTR(ret);
495 }
496 }
497
498 return keyring;
499}
500EXPORT_SYMBOL(keyring_alloc);
501
502/*
503 * Iteration function to consider each key found.
504 */
505static int keyring_search_iterator(const void *object, void *iterator_data)
506{
507 struct keyring_search_context *ctx = iterator_data;
508 const struct key *key = keyring_ptr_to_key(object);
509 unsigned long kflags = key->flags;
510
511 kenter("{%d}", key->serial);
512
513 /* ignore keys not of this type */
514 if (key->type != ctx->index_key.type) {
515 kleave(" = 0 [!type]");
516 return 0;
517 }
518
519 /* skip invalidated, revoked and expired keys */
520 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
521 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
522 (1 << KEY_FLAG_REVOKED))) {
523 ctx->result = ERR_PTR(-EKEYREVOKED);
524 kleave(" = %d [invrev]", ctx->skipped_ret);
525 goto skipped;
526 }
527
528 if (key->expiry && ctx->now.tv_sec >= key->expiry) {
529 ctx->result = ERR_PTR(-EKEYEXPIRED);
530 kleave(" = %d [expire]", ctx->skipped_ret);
531 goto skipped;
532 }
533 }
534
535 /* keys that don't match */
536 if (!ctx->match(key, ctx->match_data)) {
537 kleave(" = 0 [!match]");
538 return 0;
539 }
540
541 /* key must have search permissions */
542 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
543 key_task_permission(make_key_ref(key, ctx->possessed),
544 ctx->cred, KEY_SEARCH) < 0) {
545 ctx->result = ERR_PTR(-EACCES);
546 kleave(" = %d [!perm]", ctx->skipped_ret);
547 goto skipped;
548 }
549
550 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
551 /* we set a different error code if we pass a negative key */
552 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
553 smp_rmb();
554 ctx->result = ERR_PTR(key->type_data.reject_error);
555 kleave(" = %d [neg]", ctx->skipped_ret);
556 goto skipped;
557 }
558 }
559
560 /* Found */
561 ctx->result = make_key_ref(key, ctx->possessed);
562 kleave(" = 1 [found]");
563 return 1;
564
565skipped:
566 return ctx->skipped_ret;
567}
568
569/*
570 * Search inside a keyring for a key. We can search by walking to it
571 * directly based on its index-key or we can iterate over the entire
572 * tree looking for it, based on the match function.
573 */
574static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
575{
576 if ((ctx->flags & KEYRING_SEARCH_LOOKUP_TYPE) ==
577 KEYRING_SEARCH_LOOKUP_DIRECT) {
578 const void *object;
579
580 object = assoc_array_find(&keyring->keys,
581 &keyring_assoc_array_ops,
582 &ctx->index_key);
583 return object ? ctx->iterator(object, ctx) : 0;
584 }
585 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
586}
587
588/*
589 * Search a tree of keyrings that point to other keyrings up to the maximum
590 * depth.
591 */
592static bool search_nested_keyrings(struct key *keyring,
593 struct keyring_search_context *ctx)
594{
595 struct {
596 struct key *keyring;
597 struct assoc_array_node *node;
598 int slot;
599 } stack[KEYRING_SEARCH_MAX_DEPTH];
600
601 struct assoc_array_shortcut *shortcut;
602 struct assoc_array_node *node;
603 struct assoc_array_ptr *ptr;
604 struct key *key;
605 int sp = 0, slot;
606
607 kenter("{%d},{%s,%s}",
608 keyring->serial,
609 ctx->index_key.type->name,
610 ctx->index_key.description);
611
612 if (ctx->index_key.description)
613 ctx->index_key.desc_len = strlen(ctx->index_key.description);
614
615 /* Check to see if this top-level keyring is what we are looking for
616 * and whether it is valid or not.
617 */
618 if (ctx->flags & KEYRING_SEARCH_LOOKUP_ITERATE ||
619 keyring_compare_object(keyring, &ctx->index_key)) {
620 ctx->skipped_ret = 2;
621 ctx->flags |= KEYRING_SEARCH_DO_STATE_CHECK;
622 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
623 case 1:
624 goto found;
625 case 2:
626 return false;
627 default:
628 break;
629 }
630 }
631
632 ctx->skipped_ret = 0;
633 if (ctx->flags & KEYRING_SEARCH_NO_STATE_CHECK)
634 ctx->flags &= ~KEYRING_SEARCH_DO_STATE_CHECK;
635
636 /* Start processing a new keyring */
637descend_to_keyring:
638 kdebug("descend to %d", keyring->serial);
639 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
640 (1 << KEY_FLAG_REVOKED)))
641 goto not_this_keyring;
642
643 /* Search through the keys in this keyring before its searching its
644 * subtrees.
645 */
646 if (search_keyring(keyring, ctx))
647 goto found;
648
649 /* Then manually iterate through the keyrings nested in this one.
650 *
651 * Start from the root node of the index tree. Because of the way the
652 * hash function has been set up, keyrings cluster on the leftmost
653 * branch of the root node (root slot 0) or in the root node itself.
654 * Non-keyrings avoid the leftmost branch of the root entirely (root
655 * slots 1-15).
656 */
657 ptr = ACCESS_ONCE(keyring->keys.root);
658 if (!ptr)
659 goto not_this_keyring;
660
661 if (assoc_array_ptr_is_shortcut(ptr)) {
662 /* If the root is a shortcut, either the keyring only contains
663 * keyring pointers (everything clusters behind root slot 0) or
664 * doesn't contain any keyring pointers.
665 */
666 shortcut = assoc_array_ptr_to_shortcut(ptr);
667 smp_read_barrier_depends();
668 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
669 goto not_this_keyring;
670
671 ptr = ACCESS_ONCE(shortcut->next_node);
672 node = assoc_array_ptr_to_node(ptr);
673 goto begin_node;
674 }
675
676 node = assoc_array_ptr_to_node(ptr);
677 smp_read_barrier_depends();
678
679 ptr = node->slots[0];
680 if (!assoc_array_ptr_is_meta(ptr))
681 goto begin_node;
682
683descend_to_node:
684 /* Descend to a more distal node in this keyring's content tree and go
685 * through that.
686 */
687 kdebug("descend");
688 if (assoc_array_ptr_is_shortcut(ptr)) {
689 shortcut = assoc_array_ptr_to_shortcut(ptr);
690 smp_read_barrier_depends();
691 ptr = ACCESS_ONCE(shortcut->next_node);
692 BUG_ON(!assoc_array_ptr_is_node(ptr));
693 }
694 node = assoc_array_ptr_to_node(ptr);
695
696begin_node:
697 kdebug("begin_node");
698 smp_read_barrier_depends();
699 slot = 0;
700ascend_to_node:
701 /* Go through the slots in a node */
702 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
703 ptr = ACCESS_ONCE(node->slots[slot]);
704
705 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
706 goto descend_to_node;
707
708 if (!keyring_ptr_is_keyring(ptr))
709 continue;
710
711 key = keyring_ptr_to_key(ptr);
712
713 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
714 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
715 ctx->result = ERR_PTR(-ELOOP);
716 return false;
717 }
718 goto not_this_keyring;
719 }
720
721 /* Search a nested keyring */
722 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
723 key_task_permission(make_key_ref(key, ctx->possessed),
724 ctx->cred, KEY_SEARCH) < 0)
725 continue;
726
727 /* stack the current position */
728 stack[sp].keyring = keyring;
729 stack[sp].node = node;
730 stack[sp].slot = slot;
731 sp++;
732
733 /* begin again with the new keyring */
734 keyring = key;
735 goto descend_to_keyring;
736 }
737
738 /* We've dealt with all the slots in the current node, so now we need
739 * to ascend to the parent and continue processing there.
740 */
741 ptr = ACCESS_ONCE(node->back_pointer);
742 slot = node->parent_slot;
743
744 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
745 shortcut = assoc_array_ptr_to_shortcut(ptr);
746 smp_read_barrier_depends();
747 ptr = ACCESS_ONCE(shortcut->back_pointer);
748 slot = shortcut->parent_slot;
749 }
750 if (!ptr)
751 goto not_this_keyring;
752 node = assoc_array_ptr_to_node(ptr);
753 smp_read_barrier_depends();
754 slot++;
755
756 /* If we've ascended to the root (zero backpointer), we must have just
757 * finished processing the leftmost branch rather than the root slots -
758 * so there can't be any more keyrings for us to find.
759 */
760 if (node->back_pointer) {
761 kdebug("ascend %d", slot);
762 goto ascend_to_node;
763 }
764
765 /* The keyring we're looking at was disqualified or didn't contain a
766 * matching key.
767 */
768not_this_keyring:
769 kdebug("not_this_keyring %d", sp);
770 if (sp <= 0) {
771 kleave(" = false");
772 return false;
773 }
774
775 /* Resume the processing of a keyring higher up in the tree */
776 sp--;
777 keyring = stack[sp].keyring;
778 node = stack[sp].node;
779 slot = stack[sp].slot + 1;
780 kdebug("ascend to %d [%d]", keyring->serial, slot);
781 goto ascend_to_node;
782
783 /* We found a viable match */
784found:
785 key = key_ref_to_ptr(ctx->result);
786 key_check(key);
787 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
788 key->last_used_at = ctx->now.tv_sec;
789 keyring->last_used_at = ctx->now.tv_sec;
790 while (sp > 0)
791 stack[--sp].keyring->last_used_at = ctx->now.tv_sec;
792 }
793 kleave(" = true");
794 return true;
795}
796
797/**
798 * keyring_search_aux - Search a keyring tree for a key matching some criteria
799 * @keyring_ref: A pointer to the keyring with possession indicator.
800 * @ctx: The keyring search context.
801 *
802 * Search the supplied keyring tree for a key that matches the criteria given.
803 * The root keyring and any linked keyrings must grant Search permission to the
804 * caller to be searchable and keys can only be found if they too grant Search
805 * to the caller. The possession flag on the root keyring pointer controls use
806 * of the possessor bits in permissions checking of the entire tree. In
807 * addition, the LSM gets to forbid keyring searches and key matches.
808 *
809 * The search is performed as a breadth-then-depth search up to the prescribed
810 * limit (KEYRING_SEARCH_MAX_DEPTH).
811 *
812 * Keys are matched to the type provided and are then filtered by the match
813 * function, which is given the description to use in any way it sees fit. The
814 * match function may use any attributes of a key that it wishes to to
815 * determine the match. Normally the match function from the key type would be
816 * used.
817 *
818 * RCU can be used to prevent the keyring key lists from disappearing without
819 * the need to take lots of locks.
820 *
821 * Returns a pointer to the found key and increments the key usage count if
822 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
823 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
824 * specified keyring wasn't a keyring.
825 *
826 * In the case of a successful return, the possession attribute from
827 * @keyring_ref is propagated to the returned key reference.
828 */
829key_ref_t keyring_search_aux(key_ref_t keyring_ref,
830 struct keyring_search_context *ctx)
831{
832 struct key *keyring;
833 long err;
834
835 ctx->iterator = keyring_search_iterator;
836 ctx->possessed = is_key_possessed(keyring_ref);
837 ctx->result = ERR_PTR(-EAGAIN);
838
839 keyring = key_ref_to_ptr(keyring_ref);
840 key_check(keyring);
841
842 if (keyring->type != &key_type_keyring)
843 return ERR_PTR(-ENOTDIR);
844
845 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
846 err = key_task_permission(keyring_ref, ctx->cred, KEY_SEARCH);
847 if (err < 0)
848 return ERR_PTR(err);
849 }
850
851 rcu_read_lock();
852 ctx->now = current_kernel_time();
853 if (search_nested_keyrings(keyring, ctx))
854 __key_get(key_ref_to_ptr(ctx->result));
855 rcu_read_unlock();
856 return ctx->result;
857}
858
859/**
860 * keyring_search - Search the supplied keyring tree for a matching key
861 * @keyring: The root of the keyring tree to be searched.
862 * @type: The type of keyring we want to find.
863 * @description: The name of the keyring we want to find.
864 *
865 * As keyring_search_aux() above, but using the current task's credentials and
866 * type's default matching function and preferred search method.
867 */
868key_ref_t keyring_search(key_ref_t keyring,
869 struct key_type *type,
870 const char *description)
871{
872 struct keyring_search_context ctx = {
873 .index_key.type = type,
874 .index_key.description = description,
875 .cred = current_cred(),
876 .match = type->match,
877 .match_data = description,
878 .flags = (type->def_lookup_type |
879 KEYRING_SEARCH_DO_STATE_CHECK),
880 };
881
882 if (!ctx.match)
883 return ERR_PTR(-ENOKEY);
884
885 return keyring_search_aux(keyring, &ctx);
886}
887EXPORT_SYMBOL(keyring_search);
888
889/*
890 * Search the given keyring for a key that might be updated.
891 *
892 * The caller must guarantee that the keyring is a keyring and that the
893 * permission is granted to modify the keyring as no check is made here. The
894 * caller must also hold a lock on the keyring semaphore.
895 *
896 * Returns a pointer to the found key with usage count incremented if
897 * successful and returns NULL if not found. Revoked and invalidated keys are
898 * skipped over.
899 *
900 * If successful, the possession indicator is propagated from the keyring ref
901 * to the returned key reference.
902 */
903key_ref_t find_key_to_update(key_ref_t keyring_ref,
904 const struct keyring_index_key *index_key)
905{
906 struct key *keyring, *key;
907 const void *object;
908
909 keyring = key_ref_to_ptr(keyring_ref);
910
911 kenter("{%d},{%s,%s}",
912 keyring->serial, index_key->type->name, index_key->description);
913
914 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
915 index_key);
916
917 if (object)
918 goto found;
919
920 kleave(" = NULL");
921 return NULL;
922
923found:
924 key = keyring_ptr_to_key(object);
925 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
926 (1 << KEY_FLAG_REVOKED))) {
927 kleave(" = NULL [x]");
928 return NULL;
929 }
930 __key_get(key);
931 kleave(" = {%d}", key->serial);
932 return make_key_ref(key, is_key_possessed(keyring_ref));
933}
934
935/*
936 * Find a keyring with the specified name.
937 *
938 * All named keyrings in the current user namespace are searched, provided they
939 * grant Search permission directly to the caller (unless this check is
940 * skipped). Keyrings whose usage points have reached zero or who have been
941 * revoked are skipped.
942 *
943 * Returns a pointer to the keyring with the keyring's refcount having being
944 * incremented on success. -ENOKEY is returned if a key could not be found.
945 */
946struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
947{
948 struct key *keyring;
949 int bucket;
950
951 if (!name)
952 return ERR_PTR(-EINVAL);
953
954 bucket = keyring_hash(name);
955
956 read_lock(&keyring_name_lock);
957
958 if (keyring_name_hash[bucket].next) {
959 /* search this hash bucket for a keyring with a matching name
960 * that's readable and that hasn't been revoked */
961 list_for_each_entry(keyring,
962 &keyring_name_hash[bucket],
963 type_data.link
964 ) {
965 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
966 continue;
967
968 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
969 continue;
970
971 if (strcmp(keyring->description, name) != 0)
972 continue;
973
974 if (!skip_perm_check &&
975 key_permission(make_key_ref(keyring, 0),
976 KEY_SEARCH) < 0)
977 continue;
978
979 /* we've got a match but we might end up racing with
980 * key_cleanup() if the keyring is currently 'dead'
981 * (ie. it has a zero usage count) */
982 if (!atomic_inc_not_zero(&keyring->usage))
983 continue;
984 keyring->last_used_at = current_kernel_time().tv_sec;
985 goto out;
986 }
987 }
988
989 keyring = ERR_PTR(-ENOKEY);
990out:
991 read_unlock(&keyring_name_lock);
992 return keyring;
993}
994
995static int keyring_detect_cycle_iterator(const void *object,
996 void *iterator_data)
997{
998 struct keyring_search_context *ctx = iterator_data;
999 const struct key *key = keyring_ptr_to_key(object);
1000
1001 kenter("{%d}", key->serial);
1002
1003 /* We might get a keyring with matching index-key that is nonetheless a
1004 * different keyring. */
1005 if (key != ctx->match_data)
1006 return 0;
1007
1008 ctx->result = ERR_PTR(-EDEADLK);
1009 return 1;
1010}
1011
1012/*
1013 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1014 * tree A at the topmost level (ie: as a direct child of A).
1015 *
1016 * Since we are adding B to A at the top level, checking for cycles should just
1017 * be a matter of seeing if node A is somewhere in tree B.
1018 */
1019static int keyring_detect_cycle(struct key *A, struct key *B)
1020{
1021 struct keyring_search_context ctx = {
1022 .index_key = A->index_key,
1023 .match_data = A,
1024 .iterator = keyring_detect_cycle_iterator,
1025 .flags = (KEYRING_SEARCH_LOOKUP_DIRECT |
1026 KEYRING_SEARCH_NO_STATE_CHECK |
1027 KEYRING_SEARCH_NO_UPDATE_TIME |
1028 KEYRING_SEARCH_NO_CHECK_PERM |
1029 KEYRING_SEARCH_DETECT_TOO_DEEP),
1030 };
1031
1032 rcu_read_lock();
1033 search_nested_keyrings(B, &ctx);
1034 rcu_read_unlock();
1035 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1036}
1037
1038/*
1039 * Preallocate memory so that a key can be linked into to a keyring.
1040 */
1041int __key_link_begin(struct key *keyring,
1042 const struct keyring_index_key *index_key,
1043 struct assoc_array_edit **_edit)
1044 __acquires(&keyring->sem)
1045 __acquires(&keyring_serialise_link_sem)
1046{
1047 struct assoc_array_edit *edit;
1048 int ret;
1049
1050 kenter("%d,%s,%s,",
1051 keyring->serial, index_key->type->name, index_key->description);
1052
1053 BUG_ON(index_key->desc_len == 0);
1054
1055 if (keyring->type != &key_type_keyring)
1056 return -ENOTDIR;
1057
1058 down_write(&keyring->sem);
1059
1060 ret = -EKEYREVOKED;
1061 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1062 goto error_krsem;
1063
1064 /* serialise link/link calls to prevent parallel calls causing a cycle
1065 * when linking two keyring in opposite orders */
1066 if (index_key->type == &key_type_keyring)
1067 down_write(&keyring_serialise_link_sem);
1068
1069 /* Create an edit script that will insert/replace the key in the
1070 * keyring tree.
1071 */
1072 edit = assoc_array_insert(&keyring->keys,
1073 &keyring_assoc_array_ops,
1074 index_key,
1075 NULL);
1076 if (IS_ERR(edit)) {
1077 ret = PTR_ERR(edit);
1078 goto error_sem;
1079 }
1080
1081 /* If we're not replacing a link in-place then we're going to need some
1082 * extra quota.
1083 */
1084 if (!edit->dead_leaf) {
1085 ret = key_payload_reserve(keyring,
1086 keyring->datalen + KEYQUOTA_LINK_BYTES);
1087 if (ret < 0)
1088 goto error_cancel;
1089 }
1090
1091 *_edit = edit;
1092 kleave(" = 0");
1093 return 0;
1094
1095error_cancel:
1096 assoc_array_cancel_edit(edit);
1097error_sem:
1098 if (index_key->type == &key_type_keyring)
1099 up_write(&keyring_serialise_link_sem);
1100error_krsem:
1101 up_write(&keyring->sem);
1102 kleave(" = %d", ret);
1103 return ret;
1104}
1105
1106/*
1107 * Check already instantiated keys aren't going to be a problem.
1108 *
1109 * The caller must have called __key_link_begin(). Don't need to call this for
1110 * keys that were created since __key_link_begin() was called.
1111 */
1112int __key_link_check_live_key(struct key *keyring, struct key *key)
1113{
1114 if (key->type == &key_type_keyring)
1115 /* check that we aren't going to create a cycle by linking one
1116 * keyring to another */
1117 return keyring_detect_cycle(keyring, key);
1118 return 0;
1119}
1120
1121/*
1122 * Link a key into to a keyring.
1123 *
1124 * Must be called with __key_link_begin() having being called. Discards any
1125 * already extant link to matching key if there is one, so that each keyring
1126 * holds at most one link to any given key of a particular type+description
1127 * combination.
1128 */
1129void __key_link(struct key *key, struct assoc_array_edit **_edit)
1130{
1131 __key_get(key);
1132 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1133 assoc_array_apply_edit(*_edit);
1134 *_edit = NULL;
1135}
1136
1137/*
1138 * Finish linking a key into to a keyring.
1139 *
1140 * Must be called with __key_link_begin() having being called.
1141 */
1142void __key_link_end(struct key *keyring,
1143 const struct keyring_index_key *index_key,
1144 struct assoc_array_edit *edit)
1145 __releases(&keyring->sem)
1146 __releases(&keyring_serialise_link_sem)
1147{
1148 BUG_ON(index_key->type == NULL);
1149 kenter("%d,%s,", keyring->serial, index_key->type->name);
1150
1151 if (index_key->type == &key_type_keyring)
1152 up_write(&keyring_serialise_link_sem);
1153
1154 if (edit && !edit->dead_leaf) {
1155 key_payload_reserve(keyring,
1156 keyring->datalen - KEYQUOTA_LINK_BYTES);
1157 assoc_array_cancel_edit(edit);
1158 }
1159 up_write(&keyring->sem);
1160}
1161
1162/**
1163 * key_link - Link a key to a keyring
1164 * @keyring: The keyring to make the link in.
1165 * @key: The key to link to.
1166 *
1167 * Make a link in a keyring to a key, such that the keyring holds a reference
1168 * on that key and the key can potentially be found by searching that keyring.
1169 *
1170 * This function will write-lock the keyring's semaphore and will consume some
1171 * of the user's key data quota to hold the link.
1172 *
1173 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1174 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1175 * full, -EDQUOT if there is insufficient key data quota remaining to add
1176 * another link or -ENOMEM if there's insufficient memory.
1177 *
1178 * It is assumed that the caller has checked that it is permitted for a link to
1179 * be made (the keyring should have Write permission and the key Link
1180 * permission).
1181 */
1182int key_link(struct key *keyring, struct key *key)
1183{
1184 struct assoc_array_edit *edit;
1185 int ret;
1186
1187 kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1188
1189 key_check(keyring);
1190 key_check(key);
1191
1192 if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
1193 !test_bit(KEY_FLAG_TRUSTED, &key->flags))
1194 return -EPERM;
1195
1196 ret = __key_link_begin(keyring, &key->index_key, &edit);
1197 if (ret == 0) {
1198 kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1199 ret = __key_link_check_live_key(keyring, key);
1200 if (ret == 0)
1201 __key_link(key, &edit);
1202 __key_link_end(keyring, &key->index_key, edit);
1203 }
1204
1205 kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
1206 return ret;
1207}
1208EXPORT_SYMBOL(key_link);
1209
1210/**
1211 * key_unlink - Unlink the first link to a key from a keyring.
1212 * @keyring: The keyring to remove the link from.
1213 * @key: The key the link is to.
1214 *
1215 * Remove a link from a keyring to a key.
1216 *
1217 * This function will write-lock the keyring's semaphore.
1218 *
1219 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1220 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1221 * memory.
1222 *
1223 * It is assumed that the caller has checked that it is permitted for a link to
1224 * be removed (the keyring should have Write permission; no permissions are
1225 * required on the key).
1226 */
1227int key_unlink(struct key *keyring, struct key *key)
1228{
1229 struct assoc_array_edit *edit;
1230 int ret;
1231
1232 key_check(keyring);
1233 key_check(key);
1234
1235 if (keyring->type != &key_type_keyring)
1236 return -ENOTDIR;
1237
1238 down_write(&keyring->sem);
1239
1240 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1241 &key->index_key);
1242 if (IS_ERR(edit)) {
1243 ret = PTR_ERR(edit);
1244 goto error;
1245 }
1246 ret = -ENOENT;
1247 if (edit == NULL)
1248 goto error;
1249
1250 assoc_array_apply_edit(edit);
1251 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1252 ret = 0;
1253
1254error:
1255 up_write(&keyring->sem);
1256 return ret;
1257}
1258EXPORT_SYMBOL(key_unlink);
1259
1260/**
1261 * keyring_clear - Clear a keyring
1262 * @keyring: The keyring to clear.
1263 *
1264 * Clear the contents of the specified keyring.
1265 *
1266 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1267 */
1268int keyring_clear(struct key *keyring)
1269{
1270 struct assoc_array_edit *edit;
1271 int ret;
1272
1273 if (keyring->type != &key_type_keyring)
1274 return -ENOTDIR;
1275
1276 down_write(&keyring->sem);
1277
1278 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1279 if (IS_ERR(edit)) {
1280 ret = PTR_ERR(edit);
1281 } else {
1282 if (edit)
1283 assoc_array_apply_edit(edit);
1284 key_payload_reserve(keyring, 0);
1285 ret = 0;
1286 }
1287
1288 up_write(&keyring->sem);
1289 return ret;
1290}
1291EXPORT_SYMBOL(keyring_clear);
1292
1293/*
1294 * Dispose of the links from a revoked keyring.
1295 *
1296 * This is called with the key sem write-locked.
1297 */
1298static void keyring_revoke(struct key *keyring)
1299{
1300 struct assoc_array_edit *edit;
1301
1302 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1303 if (!IS_ERR(edit)) {
1304 if (edit)
1305 assoc_array_apply_edit(edit);
1306 key_payload_reserve(keyring, 0);
1307 }
1308}
1309
1310static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1311{
1312 struct key *key = keyring_ptr_to_key(object);
1313 time_t *limit = iterator_data;
1314
1315 if (key_is_dead(key, *limit))
1316 return false;
1317 key_get(key);
1318 return true;
1319}
1320
1321static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1322{
1323 const struct key *key = keyring_ptr_to_key(object);
1324 time_t *limit = iterator_data;
1325
1326 key_check(key);
1327 return key_is_dead(key, *limit);
1328}
1329
1330/*
1331 * Garbage collect pointers from a keyring.
1332 *
1333 * Not called with any locks held. The keyring's key struct will not be
1334 * deallocated under us as only our caller may deallocate it.
1335 */
1336void keyring_gc(struct key *keyring, time_t limit)
1337{
1338 int result;
1339
1340 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1341
1342 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1343 (1 << KEY_FLAG_REVOKED)))
1344 goto dont_gc;
1345
1346 /* scan the keyring looking for dead keys */
1347 rcu_read_lock();
1348 result = assoc_array_iterate(&keyring->keys,
1349 keyring_gc_check_iterator, &limit);
1350 rcu_read_unlock();
1351 if (result == true)
1352 goto do_gc;
1353
1354dont_gc:
1355 kleave(" [no gc]");
1356 return;
1357
1358do_gc:
1359 down_write(&keyring->sem);
1360 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1361 keyring_gc_select_iterator, &limit);
1362 up_write(&keyring->sem);
1363 kleave(" [gc]");
1364}
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}