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Message-Id: <1446688954-29589-2-git-send-email-samitolvanen@google.com>
Date: Thu, 5 Nov 2015 02:02:31 +0000
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Mikulas Patocka <mpatocka@...hat.com>,
Mandeep Baines <msb@...omium.org>,
Will Drewry <wad@...omium.org>
Cc: Alasdair Kergon <agk@...hat.com>,
Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
Mark Salyzyn <salyzyn@...gle.com>,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH 1/4] dm verity: clean up duplicate hashing code
Handle dm-verity salting in one place to simplify the code.
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
drivers/md/dm-verity.c | 262 +++++++++++++++++++++++++++----------------------
1 file changed, 147 insertions(+), 115 deletions(-)
diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index edc624b..487cb66 100644
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -173,6 +173,84 @@ static sector_t verity_position_at_level(struct dm_verity *v, sector_t block,
return block >> (level * v->hash_per_block_bits);
}
+/*
+ * Wrapper for crypto_shash_init, which handles verity salting.
+ */
+static int verity_hash_init(struct dm_verity *v, struct shash_desc *desc)
+{
+ int r;
+
+ desc->tfm = v->tfm;
+ desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+ r = crypto_shash_init(desc);
+
+ if (unlikely(r < 0)) {
+ DMERR("crypto_shash_init failed: %d", r);
+ return r;
+ }
+
+ if (likely(v->version >= 1)) {
+ r = crypto_shash_update(desc, v->salt, v->salt_size);
+
+ if (unlikely(r < 0)) {
+ DMERR("crypto_shash_update failed: %d", r);
+ return r;
+ }
+ }
+
+ return 0;
+}
+
+static int verity_hash_update(struct dm_verity *v, struct shash_desc *desc,
+ const u8 *data, size_t len)
+{
+ int r = crypto_shash_update(desc, data, len);
+
+ if (unlikely(r < 0))
+ DMERR("crypto_shash_update failed: %d", r);
+
+ return r;
+}
+
+static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc,
+ u8 *digest)
+{
+ int r;
+
+ if (unlikely(!v->version)) {
+ r = crypto_shash_update(desc, v->salt, v->salt_size);
+
+ if (r < 0) {
+ DMERR("crypto_shash_update failed: %d", r);
+ return r;
+ }
+ }
+
+ r = crypto_shash_final(desc, digest);
+
+ if (unlikely(r < 0))
+ DMERR("crypto_shash_final failed: %d", r);
+
+ return r;
+}
+
+static int verity_hash(struct dm_verity *v, struct shash_desc *desc,
+ const u8 *data, size_t len, u8 *digest)
+{
+ int r;
+
+ r = verity_hash_init(v, desc);
+ if (unlikely(r < 0))
+ return r;
+
+ r = verity_hash_update(v, desc, data, len);
+ if (unlikely(r < 0))
+ return r;
+
+ return verity_hash_final(v, desc, digest);
+}
+
static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level,
sector_t *hash_block, unsigned *offset)
{
@@ -253,10 +331,10 @@ out:
* If "skip_unverified" is false, unverified buffer is hashed and verified
* against current value of io_want_digest(v, io).
*/
-static int verity_verify_level(struct dm_verity_io *io, sector_t block,
- int level, bool skip_unverified)
+static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,
+ sector_t block, int level, bool skip_unverified,
+ u8 *want_digest)
{
- struct dm_verity *v = io->v;
struct dm_buffer *buf;
struct buffer_aux *aux;
u8 *data;
@@ -273,75 +351,72 @@ static int verity_verify_level(struct dm_verity_io *io, sector_t block,
aux = dm_bufio_get_aux_data(buf);
if (!aux->hash_verified) {
- struct shash_desc *desc;
- u8 *result;
-
if (skip_unverified) {
r = 1;
goto release_ret_r;
}
- desc = io_hash_desc(v, io);
- desc->tfm = v->tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
- r = crypto_shash_init(desc);
- if (r < 0) {
- DMERR("crypto_shash_init failed: %d", r);
+ r = verity_hash(v, io_hash_desc(v, io),
+ data, 1 << v->hash_dev_block_bits,
+ io_real_digest(v, io));
+ if (unlikely(r < 0))
goto release_ret_r;
- }
-
- if (likely(v->version >= 1)) {
- r = crypto_shash_update(desc, v->salt, v->salt_size);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
- goto release_ret_r;
- }
- }
- r = crypto_shash_update(desc, data, 1 << v->hash_dev_block_bits);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
- goto release_ret_r;
- }
-
- if (!v->version) {
- r = crypto_shash_update(desc, v->salt, v->salt_size);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
- goto release_ret_r;
- }
- }
-
- result = io_real_digest(v, io);
- r = crypto_shash_final(desc, result);
- if (r < 0) {
- DMERR("crypto_shash_final failed: %d", r);
+ if (likely(memcmp(io_real_digest(v, io), want_digest,
+ v->digest_size) == 0))
+ aux->hash_verified = 1;
+ else if (verity_handle_err(v,
+ DM_VERITY_BLOCK_TYPE_METADATA,
+ hash_block)) {
+ r = -EIO;
goto release_ret_r;
}
- if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
- if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_METADATA,
- hash_block)) {
- r = -EIO;
- goto release_ret_r;
- }
- } else
- aux->hash_verified = 1;
}
data += offset;
-
- memcpy(io_want_digest(v, io), data, v->digest_size);
-
- dm_bufio_release(buf);
- return 0;
+ memcpy(want_digest, data, v->digest_size);
+ r = 0;
release_ret_r:
dm_bufio_release(buf);
-
return r;
}
/*
+ * Find a hash for a given block, write it to digest and verify the integrity
+ * of the hash tree if necessary.
+ */
+static int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
+ sector_t block, u8 *digest)
+{
+ int i;
+ int r;
+
+ if (likely(v->levels)) {
+ /*
+ * First, we try to get the requested hash for
+ * the current block. If the hash block itself is
+ * verified, zero is returned. If it isn't, this
+ * function returns 1 and we fall back to whole
+ * chain verification.
+ */
+ r = verity_verify_level(v, io, block, 0, true, digest);
+ if (likely(r <= 0))
+ return r;
+ }
+
+ memcpy(digest, v->root_digest, v->digest_size);
+
+ for (i = v->levels - 1; i >= 0; i--) {
+ r = verity_verify_level(v, io, block, i, false, digest);
+ if (unlikely(r))
+ return r;
+ }
+
+ return 0;
+}
+
+/*
* Verify one "dm_verity_io" structure.
*/
static int verity_verify_io(struct dm_verity_io *io)
@@ -350,54 +425,21 @@ static int verity_verify_io(struct dm_verity_io *io)
struct bio *bio = dm_bio_from_per_bio_data(io,
v->ti->per_bio_data_size);
unsigned b;
- int i;
for (b = 0; b < io->n_blocks; b++) {
- struct shash_desc *desc;
- u8 *result;
int r;
unsigned todo;
+ struct shash_desc *desc = io_hash_desc(v, io);
- if (likely(v->levels)) {
- /*
- * First, we try to get the requested hash for
- * the current block. If the hash block itself is
- * verified, zero is returned. If it isn't, this
- * function returns 0 and we fall back to whole
- * chain verification.
- */
- int r = verity_verify_level(io, io->block + b, 0, true);
- if (likely(!r))
- goto test_block_hash;
- if (r < 0)
- return r;
- }
-
- memcpy(io_want_digest(v, io), v->root_digest, v->digest_size);
-
- for (i = v->levels - 1; i >= 0; i--) {
- int r = verity_verify_level(io, io->block + b, i, false);
- if (unlikely(r))
- return r;
- }
+ r = verity_hash_for_block(v, io, io->block + b,
+ io_want_digest(v, io));
+ if (unlikely(r < 0))
+ return r;
-test_block_hash:
- desc = io_hash_desc(v, io);
- desc->tfm = v->tfm;
- desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
- r = crypto_shash_init(desc);
- if (r < 0) {
- DMERR("crypto_shash_init failed: %d", r);
+ r = verity_hash_init(v, desc);
+ if (unlikely(r < 0))
return r;
- }
- if (likely(v->version >= 1)) {
- r = crypto_shash_update(desc, v->salt, v->salt_size);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
- return r;
- }
- }
todo = 1 << v->data_dev_block_bits;
do {
u8 *page;
@@ -408,37 +450,27 @@ test_block_hash:
len = bv.bv_len;
if (likely(len >= todo))
len = todo;
- r = crypto_shash_update(desc, page + bv.bv_offset, len);
+ r = verity_hash_update(v, desc, page + bv.bv_offset,
+ len);
kunmap_atomic(page);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
+ if (unlikely(r < 0))
return r;
- }
bio_advance_iter(bio, &io->iter, len);
todo -= len;
} while (todo);
- if (!v->version) {
- r = crypto_shash_update(desc, v->salt, v->salt_size);
- if (r < 0) {
- DMERR("crypto_shash_update failed: %d", r);
- return r;
- }
- }
-
- result = io_real_digest(v, io);
- r = crypto_shash_final(desc, result);
- if (r < 0) {
- DMERR("crypto_shash_final failed: %d", r);
+ r = verity_hash_final(v, desc, io_real_digest(v, io));
+ if (unlikely(r < 0))
return r;
- }
- if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) {
- if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
- io->block + b))
- return -EIO;
- }
+
+ if (likely(memcmp(io_real_digest(v, io),
+ io_want_digest(v, io), v->digest_size) == 0))
+ continue;
+ else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
+ io->block + b))
+ return -EIO;
}
return 0;
--
2.6.0.rc2.230.g3dd15c0
--
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