Merge "init: do_mounts: Add a dummy definition for dm_table_put"

drivers/md/Kconfig

@@ -517,4 +517,20 @@ config DM_LOG_WRITES
 
 	  If unsure, say N.
 
+config DM_ANDROID_VERITY
+	bool "Android verity target support"
+	depends on DM_VERITY
+	depends on X509_CERTIFICATE_PARSER
+	depends on SYSTEM_TRUSTED_KEYRING
+	depends on PUBLIC_KEY_ALGO_RSA
+	depends on KEYS
+	depends on ASYMMETRIC_KEY_TYPE
+	depends on ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+	---help---
+	  This device-mapper target is virtually a VERITY target. This
+	  target is setup by reading the metadata contents piggybacked
+	  to the actual data blocks in the block device. The signature
+	  of the metadata contents are verified against the key included
+	  in the system keyring. Upon success, the underlying verity
+	  target is setup.
 endif # MD

drivers/md/Makefile

@@ -69,3 +69,7 @@ endif
 ifeq ($(CONFIG_DM_VERITY_FEC),y)
 dm-verity-objs			+= dm-verity-fec.o
 endif
+
+ifeq ($(CONFIG_DM_ANDROID_VERITY),y)
+dm-verity-objs			+= dm-android-verity.o
+endif

drivers/md/dm-android-verity.c

@@ -0,0 +1,925 @@
+/*
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/device-mapper.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/fcntl.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/key.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/of.h>
+#include <linux/reboot.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+
+#include <asm/setup.h>
+#include <crypto/hash.h>
+#include <crypto/public_key.h>
+#include <crypto/sha.h>
+#include <keys/asymmetric-type.h>
+#include <keys/system_keyring.h>
+
+#include "dm-verity.h"
+#include "dm-android-verity.h"
+
+static char verifiedbootstate[VERITY_COMMANDLINE_PARAM_LENGTH];
+static char veritymode[VERITY_COMMANDLINE_PARAM_LENGTH];
+static char veritykeyid[VERITY_DEFAULT_KEY_ID_LENGTH];
+static char buildvariant[BUILD_VARIANT];
+
+static bool target_added;
+static bool verity_enabled = true;
+struct dentry *debug_dir;
+static int android_verity_ctr(struct dm_target *ti, unsigned argc, char **argv);
+
+static struct target_type android_verity_target = {
+	.name                   = "android-verity",
+	.version                = {1, 0, 0},
+	.module                 = THIS_MODULE,
+	.ctr                    = android_verity_ctr,
+	.dtr                    = verity_dtr,
+	.map                    = verity_map,
+	.status                 = verity_status,
+	.prepare_ioctl          = verity_prepare_ioctl,
+	.iterate_devices        = verity_iterate_devices,
+	.io_hints               = verity_io_hints,
+};
+
+static int __init verified_boot_state_param(char *line)
+{
+	strlcpy(verifiedbootstate, line, sizeof(verifiedbootstate));
+	return 1;
+}
+
+__setup("androidboot.verifiedbootstate=", verified_boot_state_param);
+
+static int __init verity_mode_param(char *line)
+{
+	strlcpy(veritymode, line, sizeof(veritymode));
+	return 1;
+}
+
+__setup("androidboot.veritymode=", verity_mode_param);
+
+static int __init verity_keyid_param(char *line)
+{
+	strlcpy(veritykeyid, line, sizeof(veritykeyid));
+	return 1;
+}
+
+__setup("veritykeyid=", verity_keyid_param);
+
+static int __init verity_buildvariant(char *line)
+{
+	strlcpy(buildvariant, line, sizeof(buildvariant));
+	return 1;
+}
+
+__setup("buildvariant=", verity_buildvariant);
+
+static inline bool default_verity_key_id(void)
+{
+	return veritykeyid[0] != '\0';
+}
+
+static inline bool is_eng(void)
+{
+	static const char typeeng[]  = "eng";
+
+	return !strncmp(buildvariant, typeeng, sizeof(typeeng));
+}
+
+static inline bool is_userdebug(void)
+{
+	static const char typeuserdebug[]  = "userdebug";
+
+	return !strncmp(buildvariant, typeuserdebug, sizeof(typeuserdebug));
+}
+
+
+static int table_extract_mpi_array(struct public_key_signature *pks,
+				const void *data, size_t len)
+{
+	MPI mpi = mpi_read_raw_data(data, len);
+
+	if (!mpi) {
+		DMERR("Error while allocating mpi array");
+		return -ENOMEM;
+	}
+
+	pks->mpi[0] = mpi;
+	pks->nr_mpi = 1;
+	return 0;
+}
+
+static struct public_key_signature *table_make_digest(
+						enum hash_algo hash,
+						const void *table,
+						unsigned long table_len)
+{
+	struct public_key_signature *pks = NULL;
+	struct crypto_shash *tfm;
+	struct shash_desc *desc;
+	size_t digest_size, desc_size;
+	int ret;
+
+	/* Allocate the hashing algorithm we're going to need and find out how
+	 * big the hash operational data will be.
+	 */
+	tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0);
+	if (IS_ERR(tfm))
+		return ERR_CAST(tfm);
+
+	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
+	digest_size = crypto_shash_digestsize(tfm);
+
+	/* We allocate the hash operational data storage on the end of out
+	 * context data and the digest output buffer on the end of that.
+	 */
+	ret = -ENOMEM;
+	pks = kzalloc(digest_size + sizeof(*pks) + desc_size, GFP_KERNEL);
+	if (!pks)
+		goto error;
+
+	pks->pkey_hash_algo = hash;
+	pks->digest = (u8 *)pks + sizeof(*pks) + desc_size;
+	pks->digest_size = digest_size;
+
+	desc = (struct shash_desc *)(pks + 1);
+	desc->tfm = tfm;
+	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+	ret = crypto_shash_init(desc);
+	if (ret < 0)
+		goto error;
+
+	ret = crypto_shash_finup(desc, table, table_len, pks->digest);
+	if (ret < 0)
+		goto error;
+
+	crypto_free_shash(tfm);
+	return pks;
+
+error:
+	kfree(pks);
+	crypto_free_shash(tfm);
+	return ERR_PTR(ret);
+}
+
+static int read_block_dev(struct bio_read *payload, struct block_device *bdev,
+		sector_t offset, int length)
+{
+	struct bio *bio;
+	int err = 0, i;
+
+	payload->number_of_pages = DIV_ROUND_UP(length, PAGE_SIZE);
+
+	bio = bio_alloc(GFP_KERNEL, payload->number_of_pages);
+	if (!bio) {
+		DMERR("Error while allocating bio");
+		return -ENOMEM;
+	}
+
+	bio->bi_bdev = bdev;
+	bio->bi_iter.bi_sector = offset;
+
+	payload->page_io = kzalloc(sizeof(struct page *) *
+		payload->number_of_pages, GFP_KERNEL);
+	if (!payload->page_io) {
+		DMERR("page_io array alloc failed");
+		err = -ENOMEM;
+		goto free_bio;
+	}
+
+	for (i = 0; i < payload->number_of_pages; i++) {
+		payload->page_io[i] = alloc_page(GFP_KERNEL);
+		if (!payload->page_io[i]) {
+			DMERR("alloc_page failed");
+			err = -ENOMEM;
+			goto free_pages;
+		}
+		if (!bio_add_page(bio, payload->page_io[i], PAGE_SIZE, 0)) {
+			DMERR("bio_add_page error");
+			err = -EIO;
+			goto free_pages;
+		}
+	}
+
+	if (!submit_bio_wait(READ, bio))
+		/* success */
+		goto free_bio;
+	DMERR("bio read failed");
+	err = -EIO;
+
+free_pages:
+	for (i = 0; i < payload->number_of_pages; i++)
+		if (payload->page_io[i])
+			__free_page(payload->page_io[i]);
+	kfree(payload->page_io);
+free_bio:
+	bio_put(bio);
+	return err;
+}
+
+static inline u64 fec_div_round_up(u64 x, u64 y)
+{
+	u64 remainder;
+
+	return div64_u64_rem(x, y, &remainder) +
+		(remainder > 0 ? 1 : 0);
+}
+
+static inline void populate_fec_metadata(struct fec_header *header,
+				struct fec_ecc_metadata *ecc)
+{
+	ecc->blocks = fec_div_round_up(le64_to_cpu(header->inp_size),
+			FEC_BLOCK_SIZE);
+	ecc->roots = le32_to_cpu(header->roots);
+	ecc->start = le64_to_cpu(header->inp_size);
+}
+
+static inline int validate_fec_header(struct fec_header *header, u64 offset)
+{
+	/* move offset to make the sanity check work for backup header
+	 * as well. */
+	offset -= offset % FEC_BLOCK_SIZE;
+	if (le32_to_cpu(header->magic) != FEC_MAGIC ||
+		le32_to_cpu(header->version) != FEC_VERSION ||
+		le32_to_cpu(header->size) != sizeof(struct fec_header) ||
+		le32_to_cpu(header->roots) == 0 ||
+		le32_to_cpu(header->roots) >= FEC_RSM)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int extract_fec_header(dev_t dev, struct fec_header *fec,
+				struct fec_ecc_metadata *ecc)
+{
+	u64 device_size;
+	struct bio_read payload;
+	int i, err = 0;
+	struct block_device *bdev;
+
+	bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
+
+	if (IS_ERR_OR_NULL(bdev)) {
+		DMERR("bdev get error");
+		return PTR_ERR(bdev);
+	}
+
+	device_size = i_size_read(bdev->bd_inode);
+
+	/* fec metadata size is a power of 2 and PAGE_SIZE
+	 * is a power of 2 as well.
+	 */
+	BUG_ON(FEC_BLOCK_SIZE > PAGE_SIZE);
+	/* 512 byte sector alignment */
+	BUG_ON(((device_size - FEC_BLOCK_SIZE) % (1 << SECTOR_SHIFT)) != 0);
+
+	err = read_block_dev(&payload, bdev, (device_size -
+		FEC_BLOCK_SIZE) / (1 << SECTOR_SHIFT), FEC_BLOCK_SIZE);
+	if (err) {
+		DMERR("Error while reading verity metadata");
+		goto error;
+	}
+
+	BUG_ON(sizeof(struct fec_header) > PAGE_SIZE);
+	memcpy(fec, page_address(payload.page_io[0]),
+			sizeof(*fec));
+
+	ecc->valid = true;
+	if (validate_fec_header(fec, device_size - FEC_BLOCK_SIZE)) {
+		/* Try the backup header */
+		memcpy(fec, page_address(payload.page_io[0]) + FEC_BLOCK_SIZE
+			- sizeof(*fec) ,
+			sizeof(*fec));
+		if (validate_fec_header(fec, device_size -
+			sizeof(struct fec_header)))
+			ecc->valid = false;
+	}
+
+	if (ecc->valid)
+		populate_fec_metadata(fec, ecc);
+
+	for (i = 0; i < payload.number_of_pages; i++)
+		__free_page(payload.page_io[i]);
+	kfree(payload.page_io);
+
+error:
+	blkdev_put(bdev, FMODE_READ);
+	return err;
+}
+static void find_metadata_offset(struct fec_header *fec,
+		struct block_device *bdev, u64 *metadata_offset)
+{
+	u64 device_size;
+
+	device_size = i_size_read(bdev->bd_inode);
+
+	if (le32_to_cpu(fec->magic) == FEC_MAGIC)
+		*metadata_offset = le64_to_cpu(fec->inp_size) -
+					VERITY_METADATA_SIZE;
+	else
+		*metadata_offset = device_size - VERITY_METADATA_SIZE;
+}
+
+static int find_size(dev_t dev, u64 *device_size)
+{
+	struct block_device *bdev;
+
+	bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
+	if (IS_ERR_OR_NULL(bdev)) {
+		DMERR("blkdev_get_by_dev failed");
+		return PTR_ERR(bdev);
+	}
+
+	*device_size = i_size_read(bdev->bd_inode);
+	*device_size >>= SECTOR_SHIFT;
+
+	DMINFO("blkdev size in sectors: %llu", *device_size);
+	blkdev_put(bdev, FMODE_READ);
+	return 0;
+}
+
+static int verify_header(struct android_metadata_header *header)
+{
+	int retval = -EINVAL;
+
+	if (is_userdebug() && le32_to_cpu(header->magic_number) ==
+			VERITY_METADATA_MAGIC_DISABLE)
+		return VERITY_STATE_DISABLE;
+
+	if (!(le32_to_cpu(header->magic_number) ==
+			VERITY_METADATA_MAGIC_NUMBER) ||
+			(le32_to_cpu(header->magic_number) ==
+			VERITY_METADATA_MAGIC_DISABLE)) {
+		DMERR("Incorrect magic number");
+		return retval;
+	}
+
+	if (le32_to_cpu(header->protocol_version) !=
+			VERITY_METADATA_VERSION) {
+		DMERR("Unsupported version %u",
+			le32_to_cpu(header->protocol_version));
+		return retval;
+	}
+
+	return 0;
+}
+
+static int extract_metadata(dev_t dev, struct fec_header *fec,
+				struct android_metadata **metadata,
+				bool *verity_enabled)
+{
+	struct block_device *bdev;
+	struct android_metadata_header *header;
+	int i;
+	u32 table_length, copy_length, offset;
+	u64 metadata_offset;
+	struct bio_read payload;
+	int err = 0;
+
+	bdev = blkdev_get_by_dev(dev, FMODE_READ, NULL);
+
+	if (IS_ERR_OR_NULL(bdev)) {
+		DMERR("blkdev_get_by_dev failed");
+		return -ENODEV;
+	}
+
+	find_metadata_offset(fec, bdev, &metadata_offset);
+
+	/* Verity metadata size is a power of 2 and PAGE_SIZE
+	 * is a power of 2 as well.
+	 * PAGE_SIZE is also a multiple of 512 bytes.
+	*/
+	if (VERITY_METADATA_SIZE > PAGE_SIZE)
+		BUG_ON(VERITY_METADATA_SIZE % PAGE_SIZE != 0);
+	/* 512 byte sector alignment */
+	BUG_ON(metadata_offset % (1 << SECTOR_SHIFT) != 0);
+
+	err = read_block_dev(&payload, bdev, metadata_offset /
+		(1 << SECTOR_SHIFT), VERITY_METADATA_SIZE);
+	if (err) {
+		DMERR("Error while reading verity metadata");
+		goto blkdev_release;
+	}
+
+	header = kzalloc(sizeof(*header), GFP_KERNEL);
+	if (!header) {
+		DMERR("kzalloc failed for header");
+		err = -ENOMEM;
+		goto free_payload;
+	}
+
+	memcpy(header, page_address(payload.page_io[0]),
+		sizeof(*header));
+
+	DMINFO("bio magic_number:%u protocol_version:%d table_length:%u",
+		le32_to_cpu(header->magic_number),
+		le32_to_cpu(header->protocol_version),
+		le32_to_cpu(header->table_length));
+
+	err = verify_header(header);
+
+	if (err == VERITY_STATE_DISABLE) {
+		DMERR("Mounting root with verity disabled");
+		*verity_enabled = false;
+		/* we would still have to read the metadata to figure out
+		 * the data blocks size. Or may be could map the entire
+		 * partition similar to mounting the device.
+		 *
+		 * Reset error as well as the verity_enabled flag is changed.
+		 */
+		err = 0;
+	} else if (err)
+		goto free_header;
+
+	*metadata = kzalloc(sizeof(**metadata), GFP_KERNEL);
+	if (!*metadata) {
+		DMERR("kzalloc for metadata failed");
+		err = -ENOMEM;
+		goto free_header;
+	}
+
+	(*metadata)->header = header;
+	table_length = le32_to_cpu(header->table_length);
+
+	if (table_length == 0 ||
+		table_length > (VERITY_METADATA_SIZE -
+			sizeof(struct android_metadata_header))) {
+		DMERR("table_length too long");
+		err = -EINVAL;
+		goto free_metadata;
+	}
+
+	(*metadata)->verity_table = kzalloc(table_length + 1, GFP_KERNEL);
+
+	if (!(*metadata)->verity_table) {
+		DMERR("kzalloc verity_table failed");
+		err = -ENOMEM;
+		goto free_metadata;
+	}
+
+	if (sizeof(struct android_metadata_header) +
+			table_length <= PAGE_SIZE) {
+		memcpy((*metadata)->verity_table,
+			page_address(payload.page_io[0])
+			+ sizeof(struct android_metadata_header),
+			table_length);
+	} else {
+		copy_length = PAGE_SIZE -
+			sizeof(struct android_metadata_header);
+		memcpy((*metadata)->verity_table,
+			page_address(payload.page_io[0])
+			+ sizeof(struct android_metadata_header),
+			copy_length);
+		table_length -= copy_length;
+		offset = copy_length;
+		i = 1;
+		while (table_length != 0) {
+			if (table_length > PAGE_SIZE) {
+				memcpy((*metadata)->verity_table + offset,
+					page_address(payload.page_io[i]),
+					PAGE_SIZE);
+				offset += PAGE_SIZE;
+				table_length -= PAGE_SIZE;
+			} else {
+				memcpy((*metadata)->verity_table + offset,
+					page_address(payload.page_io[i]),
+					table_length);
+				table_length = 0;
+			}
+			i++;
+		}
+	}
+	(*metadata)->verity_table[table_length] = '\0';
+
+	DMINFO("verity_table: %s", (*metadata)->verity_table);
+	goto free_payload;
+
+free_metadata:
+	kfree(*metadata);
+free_header:
+	kfree(header);
+free_payload:
+	for (i = 0; i < payload.number_of_pages; i++)
+		if (payload.page_io[i])
+			__free_page(payload.page_io[i]);
+	kfree(payload.page_io);
+blkdev_release:
+	blkdev_put(bdev, FMODE_READ);
+	return err;
+}
+
+/* helper functions to extract properties from dts */
+const char *find_dt_value(const char *name)
+{
+	struct device_node *firmware;
+	const char *value;
+
+	firmware = of_find_node_by_path("/firmware/android");
+	if (!firmware)
+		return NULL;
+	value = of_get_property(firmware, name, NULL);
+	of_node_put(firmware);
+
+	return value;
+}
+
+static int verity_mode(void)
+{
+	static const char enforcing[] = "enforcing";
+	static const char verified_mode_prop[] = "veritymode";
+	const char *value;
+
+	value = find_dt_value(verified_mode_prop);
+	if (!value)
+		value = veritymode;
+	if (!strncmp(value, enforcing, sizeof(enforcing) - 1))
+		return DM_VERITY_MODE_RESTART;
+
+	return DM_VERITY_MODE_EIO;
+}
+
+static int verify_verity_signature(char *key_id,
+		struct android_metadata *metadata)
+{
+	key_ref_t key_ref;
+	struct key *key;
+	struct public_key_signature *pks = NULL;
+	int retval = -EINVAL;
+
+	key_ref = keyring_search(make_key_ref(system_trusted_keyring, 1),
+		&key_type_asymmetric, key_id);
+
+	if (IS_ERR(key_ref)) {
+		DMERR("keyring: key not found");
+		return -ENOKEY;
+	}
+
+	key = key_ref_to_ptr(key_ref);
+
+	pks = table_make_digest(HASH_ALGO_SHA256,
+			(const void *)metadata->verity_table,
+			le32_to_cpu(metadata->header->table_length));
+
+	if (IS_ERR(pks)) {
+		DMERR("hashing failed");
+		goto error;
+	}
+
+	retval = table_extract_mpi_array(pks, &metadata->header->signature[0],
+				RSANUMBYTES);
+	if (retval < 0) {
+		DMERR("Error extracting mpi %d", retval);
+		goto error;
+	}
+
+	retval = verify_signature(key, pks);
+	mpi_free(pks->rsa.s);
+error:
+	kfree(pks);
+	key_put(key);
+
+	return retval;
+}
+
+static void handle_error(void)
+{
+	int mode = verity_mode();
+	if (mode == DM_VERITY_MODE_RESTART) {
+		DMERR("triggering restart");
+		kernel_restart("dm-verity device corrupted");
+	} else {
+		DMERR("Mounting verity root failed");
+	}
+}
+
+static inline bool test_mult_overflow(sector_t a, u32 b)
+{
+	sector_t r = (sector_t)~0ULL;
+
+	sector_div(r, b);
+	return a > r;
+}
+
+static int add_as_linear_device(struct dm_target *ti, char *dev)
+{
+	/*Move to linear mapping defines*/
+	char *linear_table_args[DM_LINEAR_ARGS] = {dev,
+					DM_LINEAR_TARGET_OFFSET};
+	int err = 0;
+
+	android_verity_target.dtr = dm_linear_dtr,
+	android_verity_target.map = dm_linear_map,
+	android_verity_target.status = dm_linear_status,
+	android_verity_target.prepare_ioctl = dm_linear_prepare_ioctl,
+	android_verity_target.iterate_devices = dm_linear_iterate_devices,
+	android_verity_target.io_hints = NULL;
+
+	err = dm_linear_ctr(ti, DM_LINEAR_ARGS, linear_table_args);
+
+	if (!err) {
+		DMINFO("Added android-verity as a linear target");
+		target_added = true;
+	} else
+		DMERR("Failed to add android-verity as linear target");
+
+	return err;
+}
+
+/*
+ * Target parameters:
+ *	<key id>	Key id of the public key in the system keyring.
+ *			Verity metadata's signature would be verified against
+ *			this. If the key id contains spaces, replace them
+ *			with '#'.
+ *	<block device>	The block device for which dm-verity is being setup.
+ */
+static int android_verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+	dev_t uninitialized_var(dev);
+	struct android_metadata *metadata = NULL;
+	int err = 0, i, mode;
+	char *key_id, *table_ptr, dummy, *target_device,
+	*verity_table_args[VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS];
+	/* One for specifying number of opt args and one for mode */
+	sector_t data_sectors;
+	u32 data_block_size;
+	unsigned int no_of_args = VERITY_TABLE_ARGS + 2 + VERITY_TABLE_OPT_FEC_ARGS;
+	struct fec_header uninitialized_var(fec);
+	struct fec_ecc_metadata uninitialized_var(ecc);
+	char buf[FEC_ARG_LENGTH], *buf_ptr;
+	unsigned long long tmpll;
+	u64  uninitialized_var(device_size);
+
+	if (argc == 1) {
+		/* Use the default keyid */
+		if (default_verity_key_id())
+			key_id = veritykeyid;
+		else if (!is_eng()) {
+			DMERR("veritykeyid= is not set");
+			handle_error();
+			return -EINVAL;
+		}
+	} else if (argc == 2)
+		key_id = argv[1];
+	else {
+		DMERR("Incorrect number of arguments");
+		handle_error();
+		return -EINVAL;
+	}
+
+	target_device = argv[0];
+
+	dev = name_to_dev_t(target_device);
+	if (!dev) {
+		DMERR("no dev found for %s", target_device);
+		handle_error();
+		return -EINVAL;
+	}
+
+	if (is_eng()) {
+		err = find_size(dev, &device_size);
+		if (err) {
+			DMERR("error finding bdev size");
+			handle_error();
+			return err;
+		}
+
+		ti->len = device_size;
+		err = add_as_linear_device(ti, target_device);
+		if (err) {
+			handle_error();
+			return err;
+		}
+		verity_enabled = false;
+		return 0;
+	}
+
+	strreplace(key_id, '#', ' ');
+
+	DMINFO("key:%s dev:%s", key_id, target_device);
+
+	if (extract_fec_header(dev, &fec, &ecc)) {
+		DMERR("Error while extracting fec header");
+		handle_error();
+		return -EINVAL;
+	}
+
+	err = extract_metadata(dev, &fec, &metadata, &verity_enabled);
+
+	if (err) {
+		DMERR("Error while extracting metadata");
+		handle_error();
+		goto free_metadata;
+	}
+
+	if (verity_enabled) {
+		err = verify_verity_signature(key_id, metadata);
+
+		if (err) {
+			DMERR("Signature verification failed");
+			handle_error();
+			goto free_metadata;
+		} else
+			DMINFO("Signature verification success");
+	}
+
+	table_ptr = metadata->verity_table;
+
+	for (i = 0; i < VERITY_TABLE_ARGS; i++) {
+		verity_table_args[i] = strsep(&table_ptr, " ");
+		if (verity_table_args[i] == NULL)
+			break;
+	}
+
+	if (i != VERITY_TABLE_ARGS) {
+		DMERR("Verity table not in the expected format");
+		err = -EINVAL;
+		handle_error();
+		goto free_metadata;
+	}
+
+	if (sscanf(verity_table_args[5], "%llu%c", &tmpll, &dummy)
+							!= 1) {
+		DMERR("Verity table not in the expected format");
+		handle_error();
+		err = -EINVAL;
+		goto free_metadata;
+	}
+
+	if (tmpll > ULONG_MAX) {
+		DMERR("<num_data_blocks> too large. Forgot to turn on CONFIG_LBDAF?");
+		handle_error();
+		err = -EINVAL;
+		goto free_metadata;
+	}
+
+	data_sectors = tmpll;
+
+	if (sscanf(verity_table_args[3], "%u%c", &data_block_size, &dummy)
+								!= 1) {
+		DMERR("Verity table not in the expected format");
+		handle_error();
+		err = -EINVAL;
+		goto free_metadata;
+	}
+
+	if (test_mult_overflow(data_sectors, data_block_size >>
+							SECTOR_SHIFT)) {
+		DMERR("data_sectors too large");
+		handle_error();
+		err = -EOVERFLOW;
+		goto free_metadata;
+	}
+
+	data_sectors *= data_block_size >> SECTOR_SHIFT;
+	DMINFO("Data sectors %llu", (unsigned long long)data_sectors);
+
+	/* update target length */
+	ti->len = data_sectors;
+
+	/* Setup linear target and free */
+	if (!verity_enabled) {
+		err = add_as_linear_device(ti, target_device);
+		goto free_metadata;
+	}
+
+	/*substitute data_dev and hash_dev*/
+	verity_table_args[1] = target_device;
+	verity_table_args[2] = target_device;
+
+	mode = verity_mode();
+
+	if (ecc.valid && IS_BUILTIN(CONFIG_DM_VERITY_FEC)) {
+		if (mode) {
+			err = snprintf(buf, FEC_ARG_LENGTH,
+				"%u %s " VERITY_TABLE_OPT_FEC_FORMAT,
+				1 + VERITY_TABLE_OPT_FEC_ARGS,
+				mode == DM_VERITY_MODE_RESTART ?
+					VERITY_TABLE_OPT_RESTART :
+					VERITY_TABLE_OPT_LOGGING,
+				target_device,
+				ecc.start / FEC_BLOCK_SIZE, ecc.blocks,
+				ecc.roots);
+		} else {
+			err = snprintf(buf, FEC_ARG_LENGTH,
+				"%u " VERITY_TABLE_OPT_FEC_FORMAT,
+				VERITY_TABLE_OPT_FEC_ARGS, target_device,
+				ecc.start / FEC_BLOCK_SIZE, ecc.blocks,
+				ecc.roots);
+		}
+	} else if (mode) {
+		err = snprintf(buf, FEC_ARG_LENGTH,
+			"2 " VERITY_TABLE_OPT_IGNZERO " %s",
+			mode == DM_VERITY_MODE_RESTART ?
+			VERITY_TABLE_OPT_RESTART : VERITY_TABLE_OPT_LOGGING);
+	} else {
+		err = snprintf(buf, FEC_ARG_LENGTH, "1 %s",
+				 "ignore_zero_blocks");
+	}
+
+	if (err < 0 || err >= FEC_ARG_LENGTH)
+		goto free_metadata;
+
+	buf_ptr = buf;
+
+	for (i = VERITY_TABLE_ARGS; i < (VERITY_TABLE_ARGS +
+		VERITY_TABLE_OPT_FEC_ARGS + 2); i++) {
+		verity_table_args[i] = strsep(&buf_ptr, " ");
+		if (verity_table_args[i] == NULL) {
+			no_of_args = i;
+			break;
+		}
+	}
+
+	err = verity_ctr(ti, no_of_args, verity_table_args);
+
+	if (err)
+		DMERR("android-verity failed to mount as verity target");
+	else {
+		target_added = true;
+		DMINFO("android-verity mounted as verity target");
+	}
+
+free_metadata:
+	if (metadata) {
+		kfree(metadata->header);
+		kfree(metadata->verity_table);
+	}
+	kfree(metadata);
+	return err;
+}
+
+static int __init dm_android_verity_init(void)
+{
+	int r;
+	struct dentry *file;
+
+	r = dm_register_target(&android_verity_target);
+	if (r < 0)
+		DMERR("register failed %d", r);
+
+	/* Tracks the status of the last added target */
+	debug_dir = debugfs_create_dir("android_verity", NULL);
+
+	if (IS_ERR_OR_NULL(debug_dir)) {
+		DMERR("Cannot create android_verity debugfs directory: %ld",
+			PTR_ERR(debug_dir));
+		goto end;
+	}
+
+	file = debugfs_create_bool("target_added", S_IRUGO, debug_dir,
+				&target_added);
+
+	if (IS_ERR_OR_NULL(file)) {
+		DMERR("Cannot create android_verity debugfs directory: %ld",
+			PTR_ERR(debug_dir));
+		debugfs_remove_recursive(debug_dir);
+		goto end;
+	}
+
+	file = debugfs_create_bool("verity_enabled", S_IRUGO, debug_dir,
+				&verity_enabled);
+
+	if (IS_ERR_OR_NULL(file)) {
+		DMERR("Cannot create android_verity debugfs directory: %ld",
+			PTR_ERR(debug_dir));
+		debugfs_remove_recursive(debug_dir);
+	}
+
+end:
+	return r;
+}
+
+static void __exit dm_android_verity_exit(void)
+{
+	if (!IS_ERR_OR_NULL(debug_dir))
+		debugfs_remove_recursive(debug_dir);
+
+	dm_unregister_target(&android_verity_target);
+}
+
+module_init(dm_android_verity_init);
+module_exit(dm_android_verity_exit);

drivers/md/dm-android-verity.h

@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef DM_ANDROID_VERITY_H
+#define DM_ANDROID_VERITY_H
+
+#include <crypto/sha.h>
+
+#define RSANUMBYTES 256
+#define VERITY_METADATA_MAGIC_NUMBER 0xb001b001
+#define VERITY_METADATA_MAGIC_DISABLE 0x46464f56
+#define VERITY_METADATA_VERSION 0
+#define VERITY_STATE_DISABLE 1
+#define DATA_BLOCK_SIZE (4 * 1024)
+#define VERITY_METADATA_SIZE (8 * DATA_BLOCK_SIZE)
+#define VERITY_TABLE_ARGS 10
+#define VERITY_COMMANDLINE_PARAM_LENGTH 20
+#define BUILD_VARIANT 20
+
+/*
+ * <subject>:<sha1-id> is the format for the identifier.
+ * subject can either be the Common Name(CN) + Organization Name(O) or
+ * just the CN if the it is prefixed with O
+ * From https://tools.ietf.org/html/rfc5280#appendix-A
+ * ub-organization-name-length INTEGER ::= 64
+ * ub-common-name-length INTEGER ::= 64
+ *
+ * http://lxr.free-electrons.com/source/crypto/asymmetric_keys/x509_cert_parser.c?v=3.9#L278
+ * ctx->o_size + 2 + ctx->cn_size + 1
+ * + 41 characters for ":" and sha1 id
+ * 64 + 2 + 64 + 1 + 1 + 40 (172)
+ * setting VERITY_DEFAULT_KEY_ID_LENGTH to 200 characters.
+ */
+#define VERITY_DEFAULT_KEY_ID_LENGTH 200
+
+#define FEC_MAGIC 0xFECFECFE
+#define FEC_BLOCK_SIZE (4 * 1024)
+#define FEC_VERSION 0
+#define FEC_RSM 255
+#define FEC_ARG_LENGTH 300
+
+#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
+#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
+#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"
+
+#define VERITY_TABLE_OPT_FEC_FORMAT \
+	"use_fec_from_device %s fec_start %llu fec_blocks %llu fec_roots %u ignore_zero_blocks"
+#define VERITY_TABLE_OPT_FEC_ARGS 9
+
+#define VERITY_DEBUG 0
+
+#define DM_MSG_PREFIX                   "android-verity"
+
+#define DM_LINEAR_ARGS 2
+#define DM_LINEAR_TARGET_OFFSET "0"
+
+/*
+ * There can be two formats.
+ * if fec is present
+ * <data_blocks> <verity_tree> <verity_metdata_32K><fec_data><fec_data_4K>
+ * if fec is not present
+ * <data_blocks> <verity_tree> <verity_metdata_32K>
+ */
+/* TODO: rearrange structure to reduce memory holes
+ * depends on userspace change.
+ */
+struct fec_header {
+	__le32 magic;
+	__le32 version;
+	__le32 size;
+	__le32 roots;
+	__le32 fec_size;
+	__le64 inp_size;
+	u8 hash[SHA256_DIGEST_SIZE];
+};
+
+struct android_metadata_header {
+	__le32 magic_number;
+	__le32 protocol_version;
+	char signature[RSANUMBYTES];
+	__le32 table_length;
+};
+
+struct android_metadata {
+	struct android_metadata_header *header;
+	char *verity_table;
+};
+
+struct fec_ecc_metadata {
+	bool valid;
+	u32 roots;
+	u64 blocks;
+	u64 rounds;
+	u64 start;
+};
+
+struct bio_read {
+	struct page **page_io;
+	int number_of_pages;
+};
+
+extern struct target_type linear_target;
+
+extern void dm_linear_dtr(struct dm_target *ti);
+extern int dm_linear_map(struct dm_target *ti, struct bio *bio);
+extern void dm_linear_status(struct dm_target *ti, status_type_t type,
+			unsigned status_flags, char *result, unsigned maxlen);
+extern int dm_linear_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode);
+extern int dm_linear_iterate_devices(struct dm_target *ti,
+			iterate_devices_callout_fn fn, void *data);
+extern int dm_linear_ctr(struct dm_target *ti, unsigned int argc, char **argv);
+#endif /* DM_ANDROID_VERITY_H */

drivers/md/dm-linear.c

@@ -25,7 +25,7 @@ struct linear_c {
 /*
  * Construct a linear mapping: <dev_path> <offset>
  */
-static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+int dm_linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 {
 	struct linear_c *lc;
 	unsigned long long tmp;
@@ -67,7 +67,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	return ret;
 }
 
-static void linear_dtr(struct dm_target *ti)
+void dm_linear_dtr(struct dm_target *ti)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
 
@@ -92,14 +92,14 @@ static void linear_map_bio(struct dm_target *ti, struct bio *bio)
 			linear_map_sector(ti, bio->bi_iter.bi_sector);
 }
 
-static int linear_map(struct dm_target *ti, struct bio *bio)
+int dm_linear_map(struct dm_target *ti, struct bio *bio)
 {
 	linear_map_bio(ti, bio);
 
 	return DM_MAPIO_REMAPPED;
 }
 
-static void linear_status(struct dm_target *ti, status_type_t type,
+void dm_linear_status(struct dm_target *ti, status_type_t type,
 			  unsigned status_flags, char *result, unsigned maxlen)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
@@ -116,7 +116,7 @@ static void linear_status(struct dm_target *ti, status_type_t type,
 	}
 }
 
-static int linear_prepare_ioctl(struct dm_target *ti,
+int dm_linear_prepare_ioctl(struct dm_target *ti,
 		struct block_device **bdev, fmode_t *mode)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
@@ -133,7 +133,7 @@ static int linear_prepare_ioctl(struct dm_target *ti,
 	return 0;
 }
 
-static int linear_iterate_devices(struct dm_target *ti,
+int dm_linear_iterate_devices(struct dm_target *ti,
 				  iterate_devices_callout_fn fn, void *data)
 {
 	struct linear_c *lc = ti->private;
@@ -145,12 +145,12 @@ static struct target_type linear_target = {
 	.name   = "linear",
 	.version = {1, 2, 1},
 	.module = THIS_MODULE,
-	.ctr    = linear_ctr,
-	.dtr    = linear_dtr,
-	.map    = linear_map,
-	.status = linear_status,
-	.prepare_ioctl = linear_prepare_ioctl,
-	.iterate_devices = linear_iterate_devices,
+	.ctr    = dm_linear_ctr,
+	.dtr    = dm_linear_dtr,
+	.map    = dm_linear_map,
+	.status = dm_linear_status,
+	.prepare_ioctl  = dm_linear_prepare_ioctl,
+	.iterate_devices = dm_linear_iterate_devices,
 };
 
 int __init dm_linear_init(void)

drivers/md/dm-verity-fec.c

@@ -442,6 +442,13 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
 	if (!verity_fec_is_enabled(v))
 		return -EOPNOTSUPP;
 
+	if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) {
+		DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name);
+		return -EIO;
+	}
+
+	fio->level++;
+
 	if (type == DM_VERITY_BLOCK_TYPE_METADATA)
 		block += v->data_blocks;
 
@@ -456,9 +463,7 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
 	 */
 
 	offset = block << v->data_dev_block_bits;
-
-	res = offset;
-	div64_u64(res, v->fec->rounds << v->data_dev_block_bits);
+	res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits);
 
 	/*
 	 * The base RS block we can feed to the interleaver to find out all
@@ -475,7 +480,7 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
 	if (r < 0) {
 		r = fec_decode_rsb(v, io, fio, rsb, offset, true);
 		if (r < 0)
-			return r;
+			goto done;
 	}
 
 	if (dest)
@@ -485,6 +490,8 @@ int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
 		r = verity_for_bv_block(v, io, iter, fec_bv_copy);
 	}
 
+done:
+	fio->level--;
 	return r;
 }
 
@@ -525,6 +532,7 @@ void verity_fec_init_io(struct dm_verity_io *io)
 	memset(fio->bufs, 0, sizeof(fio->bufs));
 	fio->nbufs = 0;
 	fio->output = NULL;
+	fio->level = 0;
 }
 
 /*
@@ -680,7 +688,8 @@ static struct attribute *fec_attrs[] = {
 
 static struct kobj_type fec_ktype = {
 	.sysfs_ops = &kobj_sysfs_ops,
-	.default_attrs = fec_attrs
+	.default_attrs = fec_attrs,
+	.release = dm_kobject_release
 };
 
 /*

drivers/md/dm-verity-fec.h

@@ -28,6 +28,9 @@
 #define DM_VERITY_FEC_BUF_MAX \
 	(1 << (PAGE_SHIFT - DM_VERITY_FEC_BUF_RS_BITS))
 
+/* maximum recursion level for verity_fec_decode */
+#define DM_VERITY_FEC_MAX_RECURSION	4
+
 #define DM_VERITY_OPT_FEC_DEV		"use_fec_from_device"
 #define DM_VERITY_OPT_FEC_BLOCKS	"fec_blocks"
 #define DM_VERITY_OPT_FEC_START		"fec_start"
@@ -61,6 +64,7 @@ struct dm_verity_fec_io {
 	unsigned nbufs;		/* number of buffers allocated */
 	u8 *output;		/* buffer for corrected output */
 	size_t output_pos;
+	unsigned level;		/* recursion level */
 };
 
 #ifdef CONFIG_DM_VERITY_FEC

drivers/md/dm-verity-target.c

@@ -551,7 +551,7 @@ static void verity_submit_prefetch(struct dm_verity *v, struct dm_verity_io *io)
  * Bio map function. It allocates dm_verity_io structure and bio vector and
  * fills them. Then it issues prefetches and the I/O.
  */
-static int verity_map(struct dm_target *ti, struct bio *bio)
+int verity_map(struct dm_target *ti, struct bio *bio)
 {
 	struct dm_verity *v = ti->private;
 	struct dm_verity_io *io;
@@ -596,7 +596,7 @@ static int verity_map(struct dm_target *ti, struct bio *bio)
 /*
  * Status: V (valid) or C (corruption found)
  */
-static void verity_status(struct dm_target *ti, status_type_t type,
+void verity_status(struct dm_target *ti, status_type_t type,
 			  unsigned status_flags, char *result, unsigned maxlen)
 {
 	struct dm_verity *v = ti->private;
@@ -656,7 +656,7 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 	}
 }
 
-static int verity_prepare_ioctl(struct dm_target *ti,
+int verity_prepare_ioctl(struct dm_target *ti,
 		struct block_device **bdev, fmode_t *mode)
 {
 	struct dm_verity *v = ti->private;
@@ -669,7 +669,7 @@ static int verity_prepare_ioctl(struct dm_target *ti,
 	return 0;
 }
 
-static int verity_iterate_devices(struct dm_target *ti,
+int verity_iterate_devices(struct dm_target *ti,
 				  iterate_devices_callout_fn fn, void *data)
 {
 	struct dm_verity *v = ti->private;
@@ -677,7 +677,7 @@ static int verity_iterate_devices(struct dm_target *ti,
 	return fn(ti, v->data_dev, v->data_start, ti->len, data);
 }
 
-static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
+void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct dm_verity *v = ti->private;
 
@@ -690,7 +690,7 @@ static void verity_io_hints(struct dm_target *ti, struct queue_limits *limits)
 	blk_limits_io_min(limits, limits->logical_block_size);
 }
 
-static void verity_dtr(struct dm_target *ti)
+void verity_dtr(struct dm_target *ti)
 {
 	struct dm_verity *v = ti->private;
 
@@ -817,7 +817,7 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
  *	<digest>
  *	<salt>		Hex string or "-" if no salt.
  */
-static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
+int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 {
 	struct dm_verity *v;
 	struct dm_arg_set as;

drivers/md/dm-verity.h

@@ -126,4 +126,14 @@ extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,
 extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
 				 sector_t block, u8 *digest, bool *is_zero);
 
+extern void verity_status(struct dm_target *ti, status_type_t type,
+			unsigned status_flags, char *result, unsigned maxlen);
+extern int verity_prepare_ioctl(struct dm_target *ti,
+                struct block_device **bdev, fmode_t *mode);
+extern int verity_iterate_devices(struct dm_target *ti,
+				iterate_devices_callout_fn fn, void *data);
+extern void verity_io_hints(struct dm_target *ti, struct queue_limits *limits);
+extern void verity_dtr(struct dm_target *ti);
+extern int verity_ctr(struct dm_target *ti, unsigned argc, char **argv);
+extern int verity_map(struct dm_target *ti, struct bio *bio);
 #endif /* DM_VERITY_H */

init/do_mounts.h

@@ -13,6 +13,9 @@ void  mount_block_root(char *name, int flags);
 void  mount_root(void);
 extern int root_mountflags;
 
+struct dm_table;
+static inline void dm_table_put(struct dm_table *t) { }
+
 static inline int create_dev(char *name, dev_t dev)
 {
 	sys_unlink(name);