2 * Copyright (C) 2015 Google, Inc.
4 * This software is licensed under the terms of the GNU General Public
5 * License version 2, as published by the Free Software Foundation, and
6 * may be copied, distributed, and modified under those terms.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
15 #include <linux/buffer_head.h>
16 #include <linux/debugfs.h>
17 #include <linux/delay.h>
18 #include <linux/device.h>
19 #include <linux/device-mapper.h>
20 #include <linux/errno.h>
22 #include <linux/fcntl.h>
23 #include <linux/init.h>
24 #include <linux/kernel.h>
25 #include <linux/key.h>
26 #include <linux/module.h>
27 #include <linux/mount.h>
28 #include <linux/namei.h>
30 #include <linux/reboot.h>
31 #include <linux/string.h>
32 #include <linux/vmalloc.h>
34 #include <asm/setup.h>
35 #include <crypto/hash.h>
36 #include <crypto/public_key.h>
37 #include <crypto/sha.h>
38 #include <keys/asymmetric-type.h>
39 #include <keys/system_keyring.h>
41 #include "dm-verity.h"
42 #include "dm-android-verity.h"
44 static char verifiedbootstate[VERITY_COMMANDLINE_PARAM_LENGTH];
45 static char veritymode[VERITY_COMMANDLINE_PARAM_LENGTH];
46 static char veritykeyid[VERITY_DEFAULT_KEY_ID_LENGTH];
47 static char buildvariant[BUILD_VARIANT];
49 static bool target_added;
50 static bool verity_enabled = true;
51 struct dentry *debug_dir;
52 static int android_verity_ctr(struct dm_target *ti, unsigned argc, char **argv);
54 static struct target_type android_verity_target = {
55 .name = "android-verity",
57 .module = THIS_MODULE,
58 .ctr = android_verity_ctr,
61 .status = verity_status,
62 .prepare_ioctl = verity_prepare_ioctl,
63 .iterate_devices = verity_iterate_devices,
64 .io_hints = verity_io_hints,
67 static int __init verified_boot_state_param(char *line)
69 strlcpy(verifiedbootstate, line, sizeof(verifiedbootstate));
73 __setup("androidboot.verifiedbootstate=", verified_boot_state_param);
75 static int __init verity_mode_param(char *line)
77 strlcpy(veritymode, line, sizeof(veritymode));
81 __setup("androidboot.veritymode=", verity_mode_param);
83 static int __init verity_keyid_param(char *line)
85 strlcpy(veritykeyid, line, sizeof(veritykeyid));
89 __setup("veritykeyid=", verity_keyid_param);
91 static int __init verity_buildvariant(char *line)
93 strlcpy(buildvariant, line, sizeof(buildvariant));
97 __setup("buildvariant=", verity_buildvariant);
99 static inline bool default_verity_key_id(void)
101 return veritykeyid[0] != '\0';
104 static inline bool is_eng(void)
106 static const char typeeng[] = "eng";
108 return !strncmp(buildvariant, typeeng, sizeof(typeeng));
111 static inline bool is_userdebug(void)
113 static const char typeuserdebug[] = "userdebug";
115 return !strncmp(buildvariant, typeuserdebug, sizeof(typeuserdebug));
119 static int table_extract_mpi_array(struct public_key_signature *pks,
120 const void *data, size_t len)
122 MPI mpi = mpi_read_raw_data(data, len);
125 DMERR("Error while allocating mpi array");
134 static struct public_key_signature *table_make_digest(
137 unsigned long table_len)
139 struct public_key_signature *pks = NULL;
140 struct crypto_shash *tfm;
141 struct shash_desc *desc;
142 size_t digest_size, desc_size;
145 /* Allocate the hashing algorithm we're going to need and find out how
146 * big the hash operational data will be.
148 tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0);
150 return ERR_CAST(tfm);
152 desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
153 digest_size = crypto_shash_digestsize(tfm);
155 /* We allocate the hash operational data storage on the end of out
156 * context data and the digest output buffer on the end of that.
159 pks = kzalloc(digest_size + sizeof(*pks) + desc_size, GFP_KERNEL);
163 pks->pkey_hash_algo = hash;
164 pks->digest = (u8 *)pks + sizeof(*pks) + desc_size;
165 pks->digest_size = digest_size;
167 desc = (struct shash_desc *)(pks + 1);
169 desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
171 ret = crypto_shash_init(desc);
175 ret = crypto_shash_finup(desc, table, table_len, pks->digest);
179 crypto_free_shash(tfm);
184 crypto_free_shash(tfm);
188 static int read_block_dev(struct bio_read *payload, struct block_device *bdev,
189 sector_t offset, int length)
194 payload->number_of_pages = DIV_ROUND_UP(length, PAGE_SIZE);
196 bio = bio_alloc(GFP_KERNEL, payload->number_of_pages);
198 DMERR("Error while allocating bio");
203 bio->bi_iter.bi_sector = offset;
205 payload->page_io = kzalloc(sizeof(struct page *) *
206 payload->number_of_pages, GFP_KERNEL);
207 if (!payload->page_io) {
208 DMERR("page_io array alloc failed");
213 for (i = 0; i < payload->number_of_pages; i++) {
214 payload->page_io[i] = alloc_page(GFP_KERNEL);
215 if (!payload->page_io[i]) {
216 DMERR("alloc_page failed");
220 if (!bio_add_page(bio, payload->page_io[i], PAGE_SIZE, 0)) {
221 DMERR("bio_add_page error");
227 if (!submit_bio_wait(READ, bio))
230 DMERR("bio read failed");
234 for (i = 0; i < payload->number_of_pages; i++)
235 if (payload->page_io[i])
236 __free_page(payload->page_io[i]);
237 kfree(payload->page_io);
243 static inline u64 fec_div_round_up(u64 x, u64 y)
247 return div64_u64_rem(x, y, &remainder) +
248 (remainder > 0 ? 1 : 0);
251 static inline void populate_fec_metadata(struct fec_header *header,
252 struct fec_ecc_metadata *ecc)
254 ecc->blocks = fec_div_round_up(le64_to_cpu(header->inp_size),
256 ecc->roots = le32_to_cpu(header->roots);
257 ecc->start = le64_to_cpu(header->inp_size);
260 static inline int validate_fec_header(struct fec_header *header, u64 offset)
262 /* move offset to make the sanity check work for backup header
264 offset -= offset % FEC_BLOCK_SIZE;
265 if (le32_to_cpu(header->magic) != FEC_MAGIC ||
266 le32_to_cpu(header->version) != FEC_VERSION ||
267 le32_to_cpu(header->size) != sizeof(struct fec_header) ||
268 le32_to_cpu(header->roots) == 0 ||
269 le32_to_cpu(header->roots) >= FEC_RSM)
275 static int extract_fec_header(dev_t dev, struct fec_header *fec,
276 struct fec_ecc_metadata *ecc)
279 struct bio_read payload;
281 struct block_device *bdev;
283 bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
285 if (IS_ERR_OR_NULL(bdev)) {
286 DMERR("bdev get error");
287 return PTR_ERR(bdev);
290 device_size = i_size_read(bdev->bd_inode);
292 /* fec metadata size is a power of 2 and PAGE_SIZE
293 * is a power of 2 as well.
295 BUG_ON(FEC_BLOCK_SIZE > PAGE_SIZE);
296 /* 512 byte sector alignment */
297 BUG_ON(((device_size - FEC_BLOCK_SIZE) % (1 << SECTOR_SHIFT)) != 0);
299 err = read_block_dev(&payload, bdev, (device_size -
300 FEC_BLOCK_SIZE) / (1 << SECTOR_SHIFT), FEC_BLOCK_SIZE);
302 DMERR("Error while reading verity metadata");
306 BUG_ON(sizeof(struct fec_header) > PAGE_SIZE);
307 memcpy(fec, page_address(payload.page_io[0]),
311 if (validate_fec_header(fec, device_size - FEC_BLOCK_SIZE)) {
312 /* Try the backup header */
313 memcpy(fec, page_address(payload.page_io[0]) + FEC_BLOCK_SIZE
316 if (validate_fec_header(fec, device_size -
317 sizeof(struct fec_header)))
322 populate_fec_metadata(fec, ecc);
324 for (i = 0; i < payload.number_of_pages; i++)
325 __free_page(payload.page_io[i]);
326 kfree(payload.page_io);
329 blkdev_put(bdev, FMODE_READ);
332 static void find_metadata_offset(struct fec_header *fec,
333 struct block_device *bdev, u64 *metadata_offset)
337 device_size = i_size_read(bdev->bd_inode);
339 if (le32_to_cpu(fec->magic) == FEC_MAGIC)
340 *metadata_offset = le64_to_cpu(fec->inp_size) -
341 VERITY_METADATA_SIZE;
343 *metadata_offset = device_size - VERITY_METADATA_SIZE;
346 static int find_size(dev_t dev, u64 *device_size)
348 struct block_device *bdev;
350 bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
351 if (IS_ERR_OR_NULL(bdev)) {
352 DMERR("blkdev_get_by_dev failed");
353 return PTR_ERR(bdev);
356 *device_size = i_size_read(bdev->bd_inode);
357 *device_size >>= SECTOR_SHIFT;
359 DMINFO("blkdev size in sectors: %llu", *device_size);
360 blkdev_put(bdev, FMODE_READ);
364 static int verify_header(struct android_metadata_header *header)
366 int retval = -EINVAL;
368 if (is_userdebug() && le32_to_cpu(header->magic_number) ==
369 VERITY_METADATA_MAGIC_DISABLE)
370 return VERITY_STATE_DISABLE;
372 if (!(le32_to_cpu(header->magic_number) ==
373 VERITY_METADATA_MAGIC_NUMBER) ||
374 (le32_to_cpu(header->magic_number) ==
375 VERITY_METADATA_MAGIC_DISABLE)) {
376 DMERR("Incorrect magic number");
380 if (le32_to_cpu(header->protocol_version) !=
381 VERITY_METADATA_VERSION) {
382 DMERR("Unsupported version %u",
383 le32_to_cpu(header->protocol_version));
390 static int extract_metadata(dev_t dev, struct fec_header *fec,
391 struct android_metadata **metadata,
392 bool *verity_enabled)
394 struct block_device *bdev;
395 struct android_metadata_header *header;
397 u32 table_length, copy_length, offset;
399 struct bio_read payload;
402 bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
404 if (IS_ERR_OR_NULL(bdev)) {
405 DMERR("blkdev_get_by_dev failed");
409 find_metadata_offset(fec, bdev, &metadata_offset);
411 /* Verity metadata size is a power of 2 and PAGE_SIZE
412 * is a power of 2 as well.
413 * PAGE_SIZE is also a multiple of 512 bytes.
415 if (VERITY_METADATA_SIZE > PAGE_SIZE)
416 BUG_ON(VERITY_METADATA_SIZE % PAGE_SIZE != 0);
417 /* 512 byte sector alignment */
418 BUG_ON(metadata_offset % (1 << SECTOR_SHIFT) != 0);
420 err = read_block_dev(&payload, bdev, metadata_offset /
421 (1 << SECTOR_SHIFT), VERITY_METADATA_SIZE);
423 DMERR("Error while reading verity metadata");
427 header = kzalloc(sizeof(*header), GFP_KERNEL);
429 DMERR("kzalloc failed for header");
434 memcpy(header, page_address(payload.page_io[0]),
437 DMINFO("bio magic_number:%u protocol_version:%d table_length:%u",
438 le32_to_cpu(header->magic_number),
439 le32_to_cpu(header->protocol_version),
440 le32_to_cpu(header->table_length));
442 err = verify_header(header);
444 if (err == VERITY_STATE_DISABLE) {
445 DMERR("Mounting root with verity disabled");
446 *verity_enabled = false;
447 /* we would still have to read the metadata to figure out
448 * the data blocks size. Or may be could map the entire
449 * partition similar to mounting the device.
451 * Reset error as well as the verity_enabled flag is changed.
457 *metadata = kzalloc(sizeof(**metadata), GFP_KERNEL);
459 DMERR("kzalloc for metadata failed");
464 (*metadata)->header = header;
465 table_length = le32_to_cpu(header->table_length);
467 if (table_length == 0 ||
468 table_length > (VERITY_METADATA_SIZE -
469 sizeof(struct android_metadata_header))) {
470 DMERR("table_length too long");
475 (*metadata)->verity_table = kzalloc(table_length + 1, GFP_KERNEL);
477 if (!(*metadata)->verity_table) {
478 DMERR("kzalloc verity_table failed");
483 if (sizeof(struct android_metadata_header) +
484 table_length <= PAGE_SIZE) {
485 memcpy((*metadata)->verity_table,
486 page_address(payload.page_io[0])
487 + sizeof(struct android_metadata_header),
490 copy_length = PAGE_SIZE -
491 sizeof(struct android_metadata_header);
492 memcpy((*metadata)->verity_table,
493 page_address(payload.page_io[0])
494 + sizeof(struct android_metadata_header),
496 table_length -= copy_length;
497 offset = copy_length;
499 while (table_length != 0) {
500 if (table_length > PAGE_SIZE) {
501 memcpy((*metadata)->verity_table + offset,
502 page_address(payload.page_io[i]),
505 table_length -= PAGE_SIZE;
507 memcpy((*metadata)->verity_table + offset,
508 page_address(payload.page_io[i]),
515 (*metadata)->verity_table[table_length] = '\0';
517 DMINFO("verity_table: %s", (*metadata)->verity_table);
525 for (i = 0; i < payload.number_of_pages; i++)
526 if (payload.page_io[i])
527 __free_page(payload.page_io[i]);
528 kfree(payload.page_io);
530 blkdev_put(bdev, FMODE_READ);
534 /* helper functions to extract properties from dts */
535 const char *find_dt_value(const char *name)
537 struct device_node *firmware;
540 firmware = of_find_node_by_path("/firmware/android");
543 value = of_get_property(firmware, name, NULL);
544 of_node_put(firmware);
549 static int verity_mode(void)
551 static const char enforcing[] = "enforcing";
552 static const char verified_mode_prop[] = "veritymode";
555 value = find_dt_value(verified_mode_prop);
558 if (!strncmp(value, enforcing, sizeof(enforcing) - 1))
559 return DM_VERITY_MODE_RESTART;
561 return DM_VERITY_MODE_EIO;
564 static int verify_verity_signature(char *key_id,
565 struct android_metadata *metadata)
569 struct public_key_signature *pks = NULL;
570 int retval = -EINVAL;
572 key_ref = keyring_search(make_key_ref(system_trusted_keyring, 1),
573 &key_type_asymmetric, key_id);
575 if (IS_ERR(key_ref)) {
576 DMERR("keyring: key not found");
580 key = key_ref_to_ptr(key_ref);
582 pks = table_make_digest(HASH_ALGO_SHA256,
583 (const void *)metadata->verity_table,
584 le32_to_cpu(metadata->header->table_length));
587 DMERR("hashing failed");
591 retval = table_extract_mpi_array(pks, &metadata->header->signature[0],
594 DMERR("Error extracting mpi %d", retval);
598 retval = verify_signature(key, pks);
599 mpi_free(pks->rsa.s);
607 static void handle_error(void)
609 int mode = verity_mode();
610 if (mode == DM_VERITY_MODE_RESTART) {
611 DMERR("triggering restart");
612 kernel_restart("dm-verity device corrupted");
614 DMERR("Mounting verity root failed");
618 static inline bool test_mult_overflow(sector_t a, u32 b)
620 sector_t r = (sector_t)~0ULL;
626 static int add_as_linear_device(struct dm_target *ti, char *dev)
628 /*Move to linear mapping defines*/
629 char *linear_table_args[DM_LINEAR_ARGS] = {dev,
630 DM_LINEAR_TARGET_OFFSET};
633 android_verity_target.dtr = dm_linear_dtr,
634 android_verity_target.map = dm_linear_map,
635 android_verity_target.status = dm_linear_status,
636 android_verity_target.prepare_ioctl = dm_linear_prepare_ioctl,
637 android_verity_target.iterate_devices = dm_linear_iterate_devices,
638 android_verity_target.io_hints = NULL;
640 err = dm_linear_ctr(ti, DM_LINEAR_ARGS, linear_table_args);
643 DMINFO("Added android-verity as a linear target");
646 DMERR("Failed to add android-verity as linear target");
653 * <key id> Key id of the public key in the system keyring.
654 * Verity metadata's signature would be verified against
655 * this. If the key id contains spaces, replace them
657 * <block device> The block device for which dm-verity is being setup.
659 static int android_verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
661 dev_t uninitialized_var(dev);
662 struct android_metadata *metadata = NULL;
663 int err = 0, i, mode;
664 char *key_id, *table_ptr, dummy, *target_device,
665 *verity_table_args[VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS];
666 /* One for specifying number of opt args and one for mode */
667 sector_t data_sectors;
669 unsigned int no_of_args = VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS;
670 struct fec_header uninitialized_var(fec);
671 struct fec_ecc_metadata uninitialized_var(ecc);
672 char buf[FEC_ARG_LENGTH], *buf_ptr;
673 unsigned long long tmpll;
674 u64 uninitialized_var(device_size);
677 /* Use the default keyid */
678 if (default_verity_key_id())
679 key_id = veritykeyid;
680 else if (!is_eng()) {
681 DMERR("veritykeyid= is not set");
685 } else if (argc == 2)
688 DMERR("Incorrect number of arguments");
693 target_device = argv[0];
695 dev = name_to_dev_t(target_device);
697 DMERR("no dev found for %s", target_device);
703 err = find_size(dev, &device_size);
705 DMERR("error finding bdev size");
710 ti->len = device_size;
711 err = add_as_linear_device(ti, target_device);
716 verity_enabled = false;
720 strreplace(key_id, '#', ' ');
722 DMINFO("key:%s dev:%s", key_id, target_device);
724 if (extract_fec_header(dev, &fec, &ecc)) {
725 DMERR("Error while extracting fec header");
730 err = extract_metadata(dev, &fec, &metadata, &verity_enabled);
733 DMERR("Error while extracting metadata");
738 if (verity_enabled) {
739 err = verify_verity_signature(key_id, metadata);
742 DMERR("Signature verification failed");
746 DMINFO("Signature verification success");
749 table_ptr = metadata->verity_table;
751 for (i = 0; i < VERITY_TABLE_ARGS; i++) {
752 verity_table_args[i] = strsep(&table_ptr, " ");
753 if (verity_table_args[i] == NULL)
757 if (i != VERITY_TABLE_ARGS) {
758 DMERR("Verity table not in the expected format");
764 if (sscanf(verity_table_args[5], "%llu%c", &tmpll, &dummy)
766 DMERR("Verity table not in the expected format");
772 if (tmpll > ULONG_MAX) {
773 DMERR("<num_data_blocks> too large. Forgot to turn on CONFIG_LBDAF?");
779 data_sectors = tmpll;
781 if (sscanf(verity_table_args[3], "%u%c", &data_block_size, &dummy)
783 DMERR("Verity table not in the expected format");
789 if (test_mult_overflow(data_sectors, data_block_size >>
791 DMERR("data_sectors too large");
797 data_sectors *= data_block_size >> SECTOR_SHIFT;
798 DMINFO("Data sectors %llu", (unsigned long long)data_sectors);
800 /* update target length */
801 ti->len = data_sectors;
803 /* Setup linear target and free */
804 if (!verity_enabled) {
805 err = add_as_linear_device(ti, target_device);
809 /*substitute data_dev and hash_dev*/
810 verity_table_args[1] = target_device;
811 verity_table_args[2] = target_device;
813 mode = verity_mode();
815 if (ecc.valid && IS_BUILTIN(CONFIG_DM_VERITY_FEC)) {
817 err = snprintf(buf, FEC_ARG_LENGTH,
818 "%u %s " VERITY_TABLE_OPT_FEC_FORMAT,
819 1 + VERITY_TABLE_OPT_FEC_ARGS,
820 mode == DM_VERITY_MODE_RESTART ?
821 VERITY_TABLE_OPT_RESTART :
822 VERITY_TABLE_OPT_LOGGING,
824 ecc.start / FEC_BLOCK_SIZE, ecc.blocks,
827 err = snprintf(buf, FEC_ARG_LENGTH,
828 "%u " VERITY_TABLE_OPT_FEC_FORMAT,
829 VERITY_TABLE_OPT_FEC_ARGS, target_device,
830 ecc.start / FEC_BLOCK_SIZE, ecc.blocks,
834 err = snprintf(buf, FEC_ARG_LENGTH,
835 "2 " VERITY_TABLE_OPT_IGNZERO " %s",
836 mode == DM_VERITY_MODE_RESTART ?
837 VERITY_TABLE_OPT_RESTART : VERITY_TABLE_OPT_LOGGING);
839 err = snprintf(buf, FEC_ARG_LENGTH, "1 %s",
840 "ignore_zero_blocks");
843 if (err < 0 || err >= FEC_ARG_LENGTH)
848 for (i = VERITY_TABLE_ARGS; i < (VERITY_TABLE_ARGS +
849 VERITY_TABLE_OPT_FEC_ARGS + 2); i++) {
850 verity_table_args[i] = strsep(&buf_ptr, " ");
851 if (verity_table_args[i] == NULL) {
857 err = verity_ctr(ti, no_of_args, verity_table_args);
860 DMERR("android-verity failed to mount as verity target");
863 DMINFO("android-verity mounted as verity target");
868 kfree(metadata->header);
869 kfree(metadata->verity_table);
875 static int __init dm_android_verity_init(void)
880 r = dm_register_target(&android_verity_target);
882 DMERR("register failed %d", r);
884 /* Tracks the status of the last added target */
885 debug_dir = debugfs_create_dir("android_verity", NULL);
887 if (IS_ERR_OR_NULL(debug_dir)) {
888 DMERR("Cannot create android_verity debugfs directory: %ld",
893 file = debugfs_create_bool("target_added", S_IRUGO, debug_dir,
896 if (IS_ERR_OR_NULL(file)) {
897 DMERR("Cannot create android_verity debugfs directory: %ld",
899 debugfs_remove_recursive(debug_dir);
903 file = debugfs_create_bool("verity_enabled", S_IRUGO, debug_dir,
906 if (IS_ERR_OR_NULL(file)) {
907 DMERR("Cannot create android_verity debugfs directory: %ld",
909 debugfs_remove_recursive(debug_dir);
916 static void __exit dm_android_verity_exit(void)
918 if (!IS_ERR_OR_NULL(debug_dir))
919 debugfs_remove_recursive(debug_dir);
921 dm_unregister_target(&android_verity_target);
924 module_init(dm_android_verity_init);
925 module_exit(dm_android_verity_exit);