1 files changed, 88 insertions, 13 deletions

diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-target.c
index e705799976c2..d60d15fac7e2 100644
--- a/drivers/md/dm-verity-target.c
+++ b/drivers/md/dm-verity-target.c
@@ -32,6 +32,7 @@
 #define DM_VERITY_OPT_LOGGING		"ignore_corruption"
 #define DM_VERITY_OPT_RESTART		"restart_on_corruption"
 #define DM_VERITY_OPT_IGN_ZEROES	"ignore_zero_blocks"
+#define DM_VERITY_OPT_AT_MOST_ONCE	"check_at_most_once"
 
 #define DM_VERITY_OPTS_MAX		(2 + DM_VERITY_OPTS_FEC)
 
@@ -291,8 +292,12 @@ out:
 	if (v->mode == DM_VERITY_MODE_LOGGING)
 		return 0;
 
-	if (v->mode == DM_VERITY_MODE_RESTART)
+	if (v->mode == DM_VERITY_MODE_RESTART) {
+#ifdef CONFIG_DM_VERITY_AVB
+		dm_verity_avb_error_handler();
+#endif
 		kernel_restart("dm-verity device corrupted");
+	}
 
 	return 1;
 }
@@ -490,6 +495,18 @@ static int verity_bv_zero(struct dm_verity *v, struct dm_verity_io *io,
 }
 
 /*
+ * Moves the bio iter one data block forward.
+ */
+static inline void verity_bv_skip_block(struct dm_verity *v,
+					struct dm_verity_io *io,
+					struct bvec_iter *iter)
+{
+	struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
+
+	bio_advance_iter(bio, iter, 1 << v->data_dev_block_bits);
+}
+
+/*
  * Verify one "dm_verity_io" structure.
  */
 static int verity_verify_io(struct dm_verity_io *io)
@@ -502,9 +519,16 @@ static int verity_verify_io(struct dm_verity_io *io)
 
 	for (b = 0; b < io->n_blocks; b++) {
 		int r;
+		sector_t cur_block = io->block + b;
 		struct ahash_request *req = verity_io_hash_req(v, io);
 
-		r = verity_hash_for_block(v, io, io->block + b,
+		if (v->validated_blocks &&
+		    likely(test_bit(cur_block, v->validated_blocks))) {
+			verity_bv_skip_block(v, io, &io->iter);
+			continue;
+		}
+
+		r = verity_hash_for_block(v, io, cur_block,
 					  verity_io_want_digest(v, io),
 					  &is_zero);
 		if (unlikely(r < 0))
@@ -538,13 +562,16 @@ static int verity_verify_io(struct dm_verity_io *io)
 			return r;
 
 		if (likely(memcmp(verity_io_real_digest(v, io),
-				  verity_io_want_digest(v, io), v->digest_size) == 0))
+				  verity_io_want_digest(v, io), v->digest_size) == 0)) {
+			if (v->validated_blocks)
+				set_bit(cur_block, v->validated_blocks);
 			continue;
+		}
 		else if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_DATA,
-					   io->block + b, NULL, &start) == 0)
+					   cur_block, NULL, &start) == 0)
 			continue;
 		else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,
-					   io->block + b))
+					   cur_block))
 			return -EIO;
 	}
 
@@ -648,7 +675,7 @@ 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;
@@ -693,7 +720,7 @@ 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;
@@ -730,6 +757,8 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 			args += DM_VERITY_OPTS_FEC;
 		if (v->zero_digest)
 			args++;
+		if (v->validated_blocks)
+			args++;
 		if (!args)
 			return;
 		DMEMIT(" %u", args);
@@ -748,12 +777,14 @@ static void verity_status(struct dm_target *ti, status_type_t type,
 		}
 		if (v->zero_digest)
 			DMEMIT(" " DM_VERITY_OPT_IGN_ZEROES);
+		if (v->validated_blocks)
+			DMEMIT(" " DM_VERITY_OPT_AT_MOST_ONCE);
 		sz = verity_fec_status_table(v, sz, result, maxlen);
 		break;
 	}
 }
 
-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;
@@ -766,7 +797,7 @@ 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;
@@ -774,7 +805,7 @@ 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;
 
@@ -787,7 +818,7 @@ 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;
 
@@ -797,6 +828,7 @@ static void verity_dtr(struct dm_target *ti)
 	if (v->bufio)
 		dm_bufio_client_destroy(v->bufio);
 
+	kvfree(v->validated_blocks);
 	kfree(v->salt);
 	kfree(v->root_digest);
 	kfree(v->zero_digest);
@@ -817,6 +849,26 @@ static void verity_dtr(struct dm_target *ti)
 	kfree(v);
 }
 
+static int verity_alloc_most_once(struct dm_verity *v)
+{
+	struct dm_target *ti = v->ti;
+
+	/* the bitset can only handle INT_MAX blocks */
+	if (v->data_blocks > INT_MAX) {
+		ti->error = "device too large to use check_at_most_once";
+		return -E2BIG;
+	}
+
+	v->validated_blocks = kvzalloc(BITS_TO_LONGS(v->data_blocks) *
+				       sizeof(unsigned long), GFP_KERNEL);
+	if (!v->validated_blocks) {
+		ti->error = "failed to allocate bitset for check_at_most_once";
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
 static int verity_alloc_zero_digest(struct dm_verity *v)
 {
 	int r = -ENOMEM;
@@ -886,6 +938,12 @@ static int verity_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v)
 			}
 			continue;
 
+		} else if (!strcasecmp(arg_name, DM_VERITY_OPT_AT_MOST_ONCE)) {
+			r = verity_alloc_most_once(v);
+			if (r)
+				return r;
+			continue;
+
 		} else if (verity_is_fec_opt_arg(arg_name)) {
 			r = verity_fec_parse_opt_args(as, v, &argc, arg_name);
 			if (r)
@@ -914,7 +972,7 @@ 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;
@@ -1027,6 +1085,15 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 		v->tfm = NULL;
 		goto bad;
 	}
+
+	/*
+	 * dm-verity performance can vary greatly depending on which hash
+	 * algorithm implementation is used.  Help people debug performance
+	 * problems by logging the ->cra_driver_name.
+	 */
+	DMINFO("%s using implementation \"%s\"", v->alg_name,
+	       crypto_hash_alg_common(v->tfm)->base.cra_driver_name);
+
 	v->digest_size = crypto_ahash_digestsize(v->tfm);
 	if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) {
 		ti->error = "Digest size too big";
@@ -1078,6 +1145,14 @@ static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			goto bad;
 	}
 
+#ifdef CONFIG_DM_ANDROID_VERITY_AT_MOST_ONCE_DEFAULT_ENABLED
+	if (!v->validated_blocks) {
+		r = verity_alloc_most_once(v);
+		if (r)
+			goto bad;
+	}
+#endif
+
 	v->hash_per_block_bits =
 		__fls((1 << v->hash_dev_block_bits) / v->digest_size);
 
@@ -1153,7 +1228,7 @@ bad:
 
 static struct target_type verity_target = {
 	.name		= "verity",
-	.version	= {1, 3, 0},
+	.version	= {1, 4, 0},
 	.module		= THIS_MODULE,
 	.ctr		= verity_ctr,
 	.dtr		= verity_dtr,