Hi Mikulas, This is a nice rewrite and takes advantage of your dm-bufio layer. I wish it'd existed (and or we wrote it :) in 2009 when we started this work! Some comments below: On Tue, Mar 13, 2012 at 5:20 PM, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > Hi > >> Hi Mikulus, >> >> This is some nice work. I like that you've been able to abstract a lot >> of the hash buffer management with dm-bufio. You got rid of the I/O queue. >> I've been meaning to do that for a while. The prefetch is also nice. >> We planned to do this but I decided to not do it now in order to get the >> base functionality in: >> >> http://crosbug.com/25441 >> >> However, there are some things that I don't like. I don't like comments >> either but you have none. You also removed our documentation. You are > > I added some comments. As for documentation, it's OK to use documentation > from your patch because the on-disk format and the target arguments are > the same (with an enhancement that my code supports different data and > metadata bock size and it has variable-length salt). Sounds good. >> allocated a complete shash_desc per I/O. We only allocate one per CPU. > > The hash of 4k block takes 174000 cycles. So trying to optimize > memory latency that is about 250 cycles doesn't make much sense. > > I actually observed better performance using verity on ramdisk with > workqueue unbound to specific CPUs. The reason is that the ramdisk bio > completion routine is always run on the same CPU (that one that submitted > the request), so with bound workqueue, everything was executing on one > CPU. With unbound workqueue, I got parallelism. > >> We short-circuit the hash at any level. Your implementation can only >> shirt circuit at the lowest level. > > It short-circuits hash at all levels. If the function > "verity_verify_level" finds out that "aux->hash_verified" is non-zero, it > doesn't do any hashing, it just copies the hash for the lower level. My > implementation walks the tree from the top to the bottom, but it doesn't > do hash verification if the same block has been verified before. > > All this tree-walking from the root to the bottom is 50-times faster than > the actual hashing of the data block (I measured that), so there's not > much point in trying to optimize it. I did a simple optimization (don't > walk the tree if the lowest block is already verified) and I don't need to > do anything complicated given the fact that it can't improve more than by > 2%. All we'd done was reverse the walk (we've had it both ways now :), nothing complicated, but I don't think it's a problem. >> I'd like to propose that we get the version we sent upstream and then work >> together on adding some of your enhancements incrementally. > > If you add dm-bufio support, you end up deleting majority of the original > code anyway. That's why I wrote it from scratch and that's why I didn't > attempt to morph your code. > > It's simpler to write the code from scratch and it is also less bug-prone. > >> Other than >> the changes we've made to cleanup for upstreaming, the version I >> submitted is the code we are using in production. >> >> I'm happy to add prefetch now if that is required for merging. >> >> What do you think? >> >> Regards, >> Mandeep > > This is the version with comments added: > > Mikulas > > ---- > > Remake of the google dm-verity patch. > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > --- > drivers/md/Kconfig | 17 > drivers/md/Makefile | 1 > drivers/md/dm-verity.c | 851 +++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 869 insertions(+) > > Index: linux-3.3-rc6-fast/drivers/md/Kconfig > =================================================================== > --- linux-3.3-rc6-fast.orig/drivers/md/Kconfig 2012-03-13 21:46:03.000000000 +0100 > +++ linux-3.3-rc6-fast/drivers/md/Kconfig 2012-03-13 21:46:05.000000000 +0100 > @@ -404,4 +404,21 @@ config DM_VERITY2 > > If unsure, say N. > > +config DM_VERITY > + tristate "Verity target support" > + depends on BLK_DEV_DM > + select CRYPTO > + select CRYPTO_HASH > + select DM_BUFIO > + ---help--- > + This device-mapper target allows you to create a device that > + transparently integrity checks the data on it. You'll need to > + activate the digests you're going to use in the cryptoapi > + configuration. > + > + To compile this code as a module, choose M here: the module will > + be called dm-verity. > + > + If unsure, say N. > + > endif # MD > Index: linux-3.3-rc6-fast/drivers/md/Makefile > =================================================================== > --- linux-3.3-rc6-fast.orig/drivers/md/Makefile 2012-03-13 21:46:03.000000000 +0100 > +++ linux-3.3-rc6-fast/drivers/md/Makefile 2012-03-13 21:46:05.000000000 +0100 > @@ -29,6 +29,7 @@ obj-$(CONFIG_MD_FAULTY) += faulty.o > obj-$(CONFIG_BLK_DEV_MD) += md-mod.o > obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o > obj-$(CONFIG_DM_BUFIO) += dm-bufio.o > +obj-$(CONFIG_DM_VERITY) += dm-verity.o > obj-$(CONFIG_DM_CRYPT) += dm-crypt.o > obj-$(CONFIG_DM_DELAY) += dm-delay.o > obj-$(CONFIG_DM_FLAKEY) += dm-flakey.o > Index: linux-3.3-rc6-fast/drivers/md/dm-verity.c > =================================================================== > --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > +++ linux-3.3-rc6-fast/drivers/md/dm-verity.c 2012-03-13 22:02:05.000000000 +0100 > @@ -0,0 +1,851 @@ > +/* > + * Copyright (C) 2012 Red Hat, Inc. > + * > + * Author: Mikulas Patocka <mpatocka@xxxxxxxxxx> > + * > + * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors > + * > + * This file is released under the GPLv2. > + * > + * Device mapper target parameters: > + * <version> 0 > + * <data device> > + * <hash device> > + * <hash start> (typically 0) > + * <block size> (typically 4096) > + * <algorithm> > + * <digest> > + * optional parameters: > + * <salt> (should have 32 bytes for compatibility with Google code) > + * <hash block size> (by default it is the same as data block size) > + * > + * In the file "/sys/module/dm_verity/parameters/prefetch_cluster" you can set > + * default prefetch value. Data are read in "prefetch_cluster" chunks from the > + * hash device. Prefetch cluster greatly improves performance when data and hash > + * are on the same disk on different partitions. ... on different partitions on devices with poor random access behavior. > + */ > + > +#include <linux/module.h> > +#include <linux/device-mapper.h> > +#include <crypto/hash.h> > +#include "dm-bufio.h" > + > +#define DM_MSG_PREFIX "verity" > + > +#define DM_VERITY_IO_VEC_INLINE 16 > +#define DM_VERITY_MEMPOOL_SIZE 4 > +#define DM_VERITY_DEFAULT_PREFETCH_SIZE 262144 > + > +#define DM_VERITY_MAX_LEVELS 63 > + > +static unsigned prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; > + > +module_param_named(prefetch_cluster, prefetch_cluster, uint, S_IRUGO | S_IWUSR); > + > +struct dm_verity { > + struct dm_dev *data_dev; > + struct dm_dev *hash_dev; > + struct dm_target *ti; > + struct dm_bufio_client *bufio; > + char *alg_name; > + struct crypto_shash *tfm; > + u8 *root_digest; /* digest of the root block */ > + u8 *salt; /* salt, its size is salt_size */ > + unsigned salt_size; > + sector_t data_start; /* data offset in 512-byte sectors */ > + sector_t hash_start; /* hash start in blocks */ > + sector_t data_blocks; /* the number of data blocks */ > + sector_t hash_blocks; /* the number of hash blocks */ > + unsigned char data_dev_block_bits; /* log2(data blocksize) */ > + unsigned char hash_dev_block_bits; /* log2(hash blocksize) */ > + unsigned char hash_per_block_bits; /* log2(hashes in hash block) */ > + unsigned char levels; /* the number of tree levels */ > + unsigned digest_size; /* digest size for the current hash algorithm */ > + unsigned shash_descsize;/* the size of temporary space for crypto */ > + > + mempool_t *io_mempool; /* mempool of struct dm_verity_io */ > + mempool_t *vec_mempool; /* mempool of bio vector */ > + > + struct workqueue_struct *verify_wq; > + > + /* starting blocks for each tree level. 0 is the lowest level. */ > + sector_t hash_level_block[DM_VERITY_MAX_LEVELS]; > +}; > + > +struct dm_verity_io { > + struct dm_verity *v; > + struct bio *bio; > + > + /* original values of bio->bi_end_io and bio->bi_private */ > + bio_end_io_t *orig_bi_end_io; > + void *orig_bi_private; > + > + sector_t block; > + unsigned n_blocks; > + > + /* saved bio vector */ > + struct bio_vec *io_vec; > + unsigned io_vec_size; > + > + struct work_struct work; > + > + /* a space for short vectors; longer vectors are allocated separately */ > + struct bio_vec io_vec_inline[DM_VERITY_IO_VEC_INLINE]; > + > + /* variable-size fields, accessible with functions > + io_hash_desc, io_real_digest, io_want_digest */ > + /* u8 hash_desc[crypto_shash_descsize(v->tfm)]; */ > + /* u8 real_digest[v->digest_size]; */ > + /* u8 want_digest[v->digest_size]; */ > +}; > + > +static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io) > +{ > + return (struct shash_desc *)(io + 1); > +} > + > +static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io) > +{ > + return (u8 *)(io + 1) + v->shash_descsize; > +} > + > +static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io) > +{ > + return (u8 *)(io + 1) + v->shash_descsize + v->digest_size; > +} > + > +/* > + * Auxiliary structure appended to each dm-bufio buffer. If the value > + * hash_verified is nonzero, hash of the block has been verified. > + * > + * There is no lock around this value, a race condition can at worst cause > + * that multiple processes verify the hash of the same buffer simultaneously. > + * This condition is harmless, so we don't need locking. > + */ Might be worth clarifying that no consumer will ever write a 0 value to the hash_verified field after dm_bufio_alloc_callback, as that is the critical constraint. It's what makes lockless/atomic-less access acceptable. As you say, the worst case you over verify or you over-write. bufio is nice for this use since it encapsulates the need for the atomic state transitions we were using in our module to stay lock-free. > +struct buffer_aux { > + int hash_verified; > +}; > + > +/* > + * Initialize struct buffer_aux for a freshly created buffer. > + */ > +static void dm_bufio_alloc_callback(struct dm_buffer *buf) > +{ > + struct buffer_aux *aux = dm_bufio_get_aux_data(buf); > + aux->hash_verified = 0; > +} > + > +/* > + * Translate input sector number to the sector number on the target device. > + */ > +static sector_t verity_map_sector(struct dm_verity *v, sector_t bi_sector) > +{ > + return v->data_start + dm_target_offset(v->ti, bi_sector); > +} > + > +/* > + * Return hash position of a specified block at a specified tree level > + * (0 is the lowest level). > + * The lowest "hash_per_block_bits"-bits of the result denote hash position > + * inside a hash block. The remaining bits denode location of the hash block. s/denode/denote/ > + */ > +static sector_t verity_position_at_level(struct dm_verity *v, sector_t block, > + int level) > +{ > + return block >> (level * v->hash_per_block_bits); > +} > + > +static void verity_hash_at_level(struct dm_verity *v, sector_t block, int level, > + sector_t *hash_block, unsigned *offset) > +{ > + sector_t position = verity_position_at_level(v, block, level); > + > + *hash_block = v->hash_level_block[level] + (position >> v->hash_per_block_bits); > + if (offset) > + *offset = v->digest_size * (position & ((1 << v->hash_per_block_bits) - 1)); > +} > + > +/* > + * Verify hash of a metadata block pertaining to the specified data block > + * ("block" argument) at a specified level ("level" argument). > + * > + * On successful return, io_want_digest(v, io) contains the hash value for > + * a lower tree level or for the data block (if we're at the lowest leve). > + * > + * If "skip_unverified" is true, unverified buffer is skipped an 1 is returned. > + * 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) > +{ > + struct dm_verity *v = io->v; > + struct dm_buffer *buf; > + struct buffer_aux *aux; > + u8 *data; > + int r; > + sector_t hash_block; > + unsigned offset; > + > + verity_hash_at_level(v, block, level, &hash_block, &offset); > + > + data = dm_bufio_read(v->bufio, hash_block, &buf); > + if (unlikely(IS_ERR(data))) > + return PTR_ERR(data); > + > + 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); > + 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; > + } > + > + 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); > + goto release_ret_r; > + } > + if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { > + DMERR_LIMIT("metadata block %llu is corrupted", > + (unsigned long long)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; > + > +release_ret_r: > + dm_bufio_release(buf); > + return r; > +} > + > +/* > + * Verify one "dm_verity_io" structure. > + */ > +static int verity_verify_io(struct dm_verity_io *io) > +{ > + struct dm_verity *v = io->v; > + unsigned b; > + int i; > + unsigned vector = 0, offset = 0; > + for (b = 0; b < io->n_blocks; b++) { > + struct shash_desc *desc; > + u8 *result; > + int r; > + unsigned todo; > + > + 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; > + } > + > +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); > + return r; > + } > + > + todo = 1 << v->data_dev_block_bits; > + do { > + struct bio_vec *bv; > + u8 *page; > + unsigned len; > + > + BUG_ON(vector >= io->io_vec_size); > + bv = &io->io_vec[vector]; > + page = kmap_atomic(bv->bv_page, KM_USER0); > + len = bv->bv_len - offset; > + if (likely(len >= todo)) > + len = todo; > + r = crypto_shash_update(desc, > + page + bv->bv_offset + offset, len); > + kunmap_atomic(page, KM_USER0); > + if (r < 0) { > + DMERR("crypto_shash_update failed: %d", r); > + return r; > + } > + offset += len; > + if (likely(offset == bv->bv_len)) { > + offset = 0; > + vector++; > + } > + todo -= len; > + } while (todo); > + > + 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); > + return r; > + } > + if (unlikely(memcmp(result, io_want_digest(v, io), v->digest_size))) { > + DMERR_LIMIT("data block %llu is corrupted", > + (unsigned long long)(io->block + b)); > + return -EIO; > + } > + } > + BUG_ON(vector != io->io_vec_size); > + BUG_ON(offset); > + return 0; > +} > + > +/* > + * End one "io" structure with a given error. > + */ > +static void verity_finish_io(struct dm_verity_io *io, int error) > +{ > + struct bio *bio = io->bio; > + struct dm_verity *v = io->v; > + > + bio->bi_end_io = io->orig_bi_end_io; > + bio->bi_private = io->orig_bi_private; > + > + if (io->io_vec != io->io_vec_inline) > + mempool_free(io->io_vec, v->vec_mempool); > + mempool_free(io, v->io_mempool); > + > + bio_endio(bio, error); > +} > + > +static void verity_work(struct work_struct *w) > +{ > + struct dm_verity_io *io = container_of(w, struct dm_verity_io, work); > + > + verity_finish_io(io, verity_verify_io(io)); > +} > + > +static void verity_end_io(struct bio *bio, int error) > +{ > + struct dm_verity_io *io = bio->bi_private; > + if (error) { > + verity_finish_io(io, error); > + return; > + } > + > + INIT_WORK(&io->work, verity_work); > + queue_work(io->v->verify_wq, &io->work); > +} > + > +/* > + * Prefetch buffers for the specified io. > + * The root buffer is not prefetched, it is assumed that it will be cached > + * all the time. > + */ > +static void verity_prefetch_io(struct dm_verity *v, struct dm_verity_io *io) > +{ > + int i; > + for (i = v->levels - 2; i >= 0; i--) { > + sector_t hash_block_start; > + sector_t hash_block_end; > + verity_hash_at_level(v, io->block, i, &hash_block_start, NULL); > + verity_hash_at_level(v, io->block + io->n_blocks - 1, i, &hash_block_end, NULL); > + if (!i) { > + unsigned cluster = prefetch_cluster; > + /* barrier to stop GCC from re-reading prefetch_cluster again */ > + barrier(); > + cluster >>= v->data_dev_block_bits; Would: unsigned cluster = prefetch_cluster >> v->data_dev_block_bits; not have similar behavior without a barrier? (Yeah yeah I could compile and see, but I was curious if you already had.) Since the max iterations here is 61 in a worst-case, I don't think it's a big deal to barrier() each time, just thought I'd ask. > + if (unlikely(!cluster)) > + goto no_prefetch_cluster; > + if (unlikely(cluster & (cluster - 1))) > + cluster = 1 << (fls(cluster) - 1); > + > + hash_block_start &= ~(sector_t)(cluster - 1); > + hash_block_end |= cluster - 1; > + if (unlikely(hash_block_end >= v->hash_blocks)) > + hash_block_end = v->hash_blocks - 1; > + } > +no_prefetch_cluster: > + dm_bufio_prefetch(v->bufio, hash_block_start, > + hash_block_end - hash_block_start + 1); > + } > +} > + > +/* > + * 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, > + union map_info *map_context) > +{ > + struct dm_verity *v = ti->private; > + struct dm_verity_io *io; > + > + if (((unsigned)bio->bi_sector | bio_sectors(bio)) & > + ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { > + DMERR_LIMIT("unaligned io"); > + return -EIO; > + } > + > + if ((bio->bi_sector + bio_sectors(bio)) >> > + (v->data_dev_block_bits - SECTOR_SHIFT) > v->data_blocks) { > + DMERR_LIMIT("io out of range"); > + return -EIO; > + } > + > + if (bio_data_dir(bio) == WRITE) > + return -EIO; > + > + io = mempool_alloc(v->io_mempool, GFP_NOIO); > + io->v = v; > + io->bio = bio; > + io->orig_bi_end_io = bio->bi_end_io; > + io->orig_bi_private = bio->bi_private; > + io->block = bio->bi_sector >> (v->data_dev_block_bits - SECTOR_SHIFT); > + io->n_blocks = bio->bi_size >> v->data_dev_block_bits; > + > + bio->bi_end_io = verity_end_io; > + bio->bi_private = io; > + bio->bi_bdev = v->data_dev->bdev; > + bio->bi_sector = verity_map_sector(v, bio->bi_sector); > + > + io->io_vec_size = bio->bi_vcnt - bio->bi_idx; > + if (io->io_vec_size < DM_VERITY_IO_VEC_INLINE) > + io->io_vec = io->io_vec_inline; > + else > + io->io_vec = mempool_alloc(v->vec_mempool, GFP_NOIO); > + memcpy(io->io_vec, bio_iovec(bio), > + io->io_vec_size * sizeof(struct bio_vec)); > + > + verity_prefetch_io(v, io); > + > + generic_make_request(bio); > + > + return DM_MAPIO_SUBMITTED; > +} > + > +static int verity_status(struct dm_target *ti, status_type_t type, > + char *result, unsigned maxlen) > +{ > + struct dm_verity *v = ti->private; > + unsigned sz = 0; > + unsigned x; > + > + switch (type) { > + case STATUSTYPE_INFO: > + result[0] = 0; > + break; > + case STATUSTYPE_TABLE: > + DMEMIT("%u %s %s %llu %u %s ", > + 0, > + v->data_dev->name, > + v->hash_dev->name, I understand the new approach is to use major:minor instead of the device name. I don't care which, but I believe agk@ requested that. > + (unsigned long long)v->hash_start << (v->hash_dev_block_bits - SECTOR_SHIFT), > + 1 << v->data_dev_block_bits, > + v->alg_name > + ); > + for (x = 0; x < v->digest_size; x++) > + DMEMIT("%02x", v->root_digest[x]); > + DMEMIT(" "); > + if (!v->salt_size) > + DMEMIT("-"); > + else > + for (x = 0; x < v->salt_size; x++) > + DMEMIT("%02x", v->salt[x]); > + if (v->data_dev_block_bits != v->hash_dev_block_bits) > + DMEMIT(" %u", 1 << v->hash_dev_block_bits); > + break; > + } > + return 0; > +} > + > +static int verity_ioctl(struct dm_target *ti, unsigned cmd, > + unsigned long arg) > +{ > + struct dm_verity *v = ti->private; > + int r = 0; > + > + if (v->data_start || > + ti->len != i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) > + r = scsi_verify_blk_ioctl(NULL, cmd); > + Is it worth supporting ioctl at all given these hoops? Nothing stops a privileged user from directly running the ioctl on the underlying device/devices, it's just very inconvenient :) > + return r ? : __blkdev_driver_ioctl(v->data_dev->bdev, v->data_dev->mode, > + cmd, arg); > +} > + > +static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm, > + struct bio_vec *biovec, int max_size) > +{ > + struct dm_verity *v = ti->private; > + struct request_queue *q = bdev_get_queue(v->data_dev->bdev); > + > + if (!q->merge_bvec_fn) > + return max_size; > + > + bvm->bi_bdev = v->data_dev->bdev; > + bvm->bi_sector = verity_map_sector(v, bvm->bi_sector); > + > + return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); > +} > + > +static int verity_iterate_devices(struct dm_target *ti, > + iterate_devices_callout_fn fn, void *data) > +{ > + struct dm_verity *v = ti->private; > + 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) > +{ > + struct dm_verity *v = ti->private; > + > + if (limits->logical_block_size < 1 << v->data_dev_block_bits) > + limits->logical_block_size = 1 << v->data_dev_block_bits; > + if (limits->physical_block_size < 1 << v->data_dev_block_bits) > + limits->physical_block_size = 1 << v->data_dev_block_bits; > + blk_limits_io_min(limits, limits->logical_block_size); > +} > + > +static void verity_dtr(struct dm_target *ti); > + > +static int verity_ctr(struct dm_target *ti, unsigned argc, char **argv) > +{ > + struct dm_verity *v; > + unsigned num; > + unsigned long long hs; > + int r; > + int i; > + sector_t hash_position; > + char dummy; > + > + v = kzalloc(sizeof(struct dm_verity), GFP_KERNEL); > + if (!v) { > + ti->error = "Cannot allocate verity structure"; > + return -ENOMEM; > + } > + ti->private = v; > + v->ti = ti; > + > + if ((dm_table_get_mode(ti->table) & ~FMODE_READ) != 0) { > + ti->error = "Device must be readonly"; > + r = -EINVAL; > + goto bad; > + } > + > + if (argc < 7) { > + ti->error = "Not enough arguments"; > + r = -EINVAL; > + goto bad; > + } > + > + if (sscanf(argv[0], "%d%c", &num, &dummy) != 1 || > + num != 0) { > + ti->error = "Invalid version"; > + r = -EINVAL; > + goto bad; > + } > + > + r = dm_get_device(ti, argv[1], FMODE_READ, &v->data_dev); > + if (r) { > + ti->error = "Data device lookup failed"; > + goto bad; > + } > + > + r = dm_get_device(ti, argv[2], FMODE_READ, &v->hash_dev); > + if (r) { > + ti->error = "Data device lookup failed"; > + goto bad; > + } > + > + if (sscanf(argv[3], "%llu%c", &hs, &dummy) != 1 || > + hs != (sector_t)hs) { > + ti->error = "Invalid hash start"; > + r = -EINVAL; > + goto bad; > + } > + > + if (sscanf(argv[4], "%u%c", &num, &dummy) != 1 || > + !num || (num & (num - 1)) || > + num < bdev_logical_block_size(v->data_dev->bdev) || > + num > PAGE_SIZE) { > + ti->error = "Invalid data device block size"; > + r = -EINVAL; > + goto bad; > + } > + v->data_dev_block_bits = ffs(num) - 1; > + v->hash_dev_block_bits = ffs(num) - 1; > + > + v->alg_name = kstrdup(argv[5], GFP_KERNEL); > + if (!v->alg_name) { > + ti->error = "Cannot allocate algorithm name"; > + r = -ENOMEM; > + goto bad; > + } > + > + v->tfm = crypto_alloc_shash(v->alg_name, 0, 0); > + if (IS_ERR(v->tfm)) { > + ti->error = "Cannot initialize hash function"; > + r = PTR_ERR(v->tfm); > + v->tfm = NULL; > + goto bad; > + } > + v->digest_size = crypto_shash_digestsize(v->tfm); > + if ((1 << v->hash_dev_block_bits) < v->digest_size * 2) { > + ti->error = "Digest size too big"; > + r = -EINVAL; > + goto bad; > + } > + v->shash_descsize = > + sizeof(struct shash_desc) + crypto_shash_descsize(v->tfm); > + > + v->root_digest = kmalloc(v->digest_size, GFP_KERNEL); > + if (!v->root_digest) { > + ti->error = "Cannot allocate root digest"; > + r = -ENOMEM; > + goto bad; > + } > + if (strlen(argv[6]) != v->digest_size * 2 || > + hex2bin(v->root_digest, argv[6], v->digest_size)) { > + ti->error = "Invalid root digest"; > + r = -EINVAL; > + goto bad; > + } > + > + if (argc > 7 && strcmp(argv[7], "-")) { > + v->salt_size = strlen(argv[7]) / 2; > + v->salt = kmalloc(v->salt_size, GFP_KERNEL); > + if (!v->salt) { > + ti->error = "Cannot allocate salt"; > + r = -ENOMEM; > + goto bad; > + } > + if (strlen(argv[7]) != v->salt_size * 2 || > + hex2bin(v->salt, argv[7], v->salt_size)) { > + ti->error = "Invalid salt"; > + r = -EINVAL; > + goto bad; > + } > + } > + > + if (argc > 8) { > + if (sscanf(argv[8], "%u%c", &num, &dummy) != 1 || > + !num || (num & (num - 1)) || > + num < bdev_logical_block_size(v->hash_dev->bdev) || > + num > INT_MAX) { > + ti->error = "Invalid hash device block size"; > + r = -EINVAL; > + goto bad; > + } > + v->hash_dev_block_bits = ffs(num) - 1; > + } > + > + if (hs & ((1 << (v->hash_dev_block_bits - SECTOR_SHIFT)) - 1)) { > + ti->error = "Hash start not aligned on block boundary"; > + r = -EINVAL; > + goto bad; > + } > + v->hash_start = hs >> (v->hash_dev_block_bits - SECTOR_SHIFT); > + > + if (ti->len > i_size_read(v->data_dev->bdev->bd_inode) >> SECTOR_SHIFT) { > + ti->error = "Data device si too small"; s/si/is Should this also check ti->start + ti->len to ensure it isn't reading off the end or do you just rely on the requests failing? > + r = -EINVAL; > + goto bad; > + } > + > + if (ti->len & ((1 << (v->data_dev_block_bits - SECTOR_SHIFT)) - 1)) { > + ti->error = "Data device length is not aligned to block size"; > + r = -EINVAL; > + goto bad; > + } > + > + v->data_blocks = ti->len >> (v->data_dev_block_bits - SECTOR_SHIFT); > + > + v->hash_per_block_bits = > + fls((1 << v->hash_dev_block_bits) / v->digest_size) - 1; > + > + v->levels = 0; > + if (v->data_blocks) > + while (v->hash_per_block_bits * v->levels < 64 && > + (unsigned long long)(v->data_blocks - 1) >> > + (v->hash_per_block_bits * v->levels)) > + v->levels++; > + > + if (v->levels > DM_VERITY_MAX_LEVELS) { > + ti->error = "Too many tree levels"; > + r = -E2BIG; > + goto bad; > + } > + > + hash_position = v->hash_start; > + for (i = v->levels - 1; i >= 0; i--) { > + sector_t s; > + v->hash_level_block[i] = hash_position; > + s = verity_position_at_level(v, v->data_blocks, i); > + s = (s >> v->hash_per_block_bits) + > + !!(s & ((1 << v->hash_per_block_bits) - 1)); > + if (hash_position + s < hash_position) { > + ti->error = "Hash device offset overflow"; > + r = -E2BIG; > + goto bad; > + } > + hash_position += s; > + } > + v->hash_blocks = hash_position; > + > + v->bufio = dm_bufio_client_create(v->hash_dev->bdev, > + 1 << v->hash_dev_block_bits, 1, sizeof(struct buffer_aux), > + dm_bufio_alloc_callback, NULL); > + if (IS_ERR(v->bufio)) { > + ti->error = "Cannot initialize dm-bufio"; > + r = PTR_ERR(v->bufio); > + v->bufio = NULL; > + goto bad; > + } > + > + if (dm_bufio_get_device_size(v->bufio) < v->hash_blocks) { > + ti->error = "Hash device is too small"; > + r = -E2BIG; > + goto bad; > + } > + > + v->io_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, > + sizeof(struct dm_verity_io) + v->shash_descsize + v->digest_size * 2); > + if (!v->io_mempool) { > + ti->error = "Cannot allocate io mempool"; > + r = -ENOMEM; > + goto bad; > + } > + > + v->vec_mempool = mempool_create_kmalloc_pool(DM_VERITY_MEMPOOL_SIZE, > + BIO_MAX_PAGES * sizeof(struct bio_vec)); > + if (!v->vec_mempool) { > + ti->error = "Cannot allocate vector mempool"; > + r = -ENOMEM; > + goto bad; > + } > + > + /*v->verify_wq = alloc_workqueue("verityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM, 1);*/ > + /* WQ_UNBOUND greatly improves performance when running on ramdisk */ > + v->verify_wq = alloc_workqueue("verityd", WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND, num_online_cpus()); > + if (!v->verify_wq) { > + ti->error = "Cannot allocate workqueue"; > + r = -ENOMEM; > + goto bad; > + } > + > + return 0; > + > +bad: > + verity_dtr(ti); > + return r; > +} > + > +static void verity_dtr(struct dm_target *ti) > +{ > + struct dm_verity *v = ti->private; > + > + if (v->verify_wq) > + destroy_workqueue(v->verify_wq); > + if (v->vec_mempool) > + mempool_destroy(v->vec_mempool); > + if (v->io_mempool) > + mempool_destroy(v->io_mempool); > + if (v->bufio) > + dm_bufio_client_destroy(v->bufio); > + kfree(v->salt); > + kfree(v->root_digest); > + if (v->tfm) > + crypto_free_shash(v->tfm); > + kfree(v->alg_name); > + if (v->hash_dev) > + dm_put_device(ti, v->hash_dev); > + if (v->data_dev) > + dm_put_device(ti, v->data_dev); > + kfree(v); > +} > + > +static struct target_type verity_target = { > + .name = "verity", > + .version = {1, 0, 0}, > + .module = THIS_MODULE, > + .ctr = verity_ctr, > + .dtr = verity_dtr, > + .map = verity_map, > + .status = verity_status, > + .ioctl = verity_ioctl, > + .merge = verity_merge, > + .iterate_devices = verity_iterate_devices, > + .io_hints = verity_io_hints, > +}; > + > +static int __init dm_verity_init(void) > +{ > + int r; > + r = dm_register_target(&verity_target); > + if (r < 0) > + DMERR("register failed %d", r); > + return r; > +} > + > +static void __exit dm_verity_exit(void) > +{ > + dm_unregister_target(&verity_target); > +} > + > +module_init(dm_verity_init); > +module_exit(dm_verity_exit); > + > +MODULE_AUTHOR("Mikulas Patocka <mpatocka@xxxxxxxxxx>"); As per linux/module.h, I'd welcome additional authors as per the lkml/patch lineage: MODULE_AUTHOR("Mandeep Baines <msb@xxxxxxxxxxxx>"); MODULE_AUTHOR("Will Drewry <wad@xxxxxxxxxxxx>"); Regardless, I'll just be happy to see this functionality merge. > +MODULE_DESCRIPTION(DM_NAME " target for transparent disk integrity checking"); > +MODULE_LICENSE("GPL"); > + > Index: linux-3.3-rc6-fast/drivers/md/dm-bufio.c This should be in a separate patch I think. > =================================================================== > --- linux-3.3-rc6-fast.orig/drivers/md/dm-bufio.c 2012-03-12 22:43:23.000000000 +0100 > +++ linux-3.3-rc6-fast/drivers/md/dm-bufio.c 2012-03-13 15:41:02.000000000 +0100 [snip] > @@ -882,6 +888,19 @@ static struct dm_buffer *__bufio_new(str > > b = __find(c, block); > if (b) { > +found_buffer: > + if (nf == NF_PREFETCH) > + return NULL; > + /* > + * Note: it is essential that we don't wait for the buffer to be > + * read if dm_bufio_get function is used. Both dm_bufio_get and > + * dm_bufio_prefetch can be used in the driver request routine. > + * If the user called both dm_bufio_prefetch and dm_bufio_get on > + * the same buffer, it would deadlock if we waited. > + */ > + if (nf == NF_GET && unlikely(test_bit(B_READING, &b->state))) > + return NULL; > + > b->hold_count++; Are these hold_counts safe on architectures with weak memory models? Should they be atomic_ts? I haven't looked at them in context, but based on what I see here they make me a bit nervous. Thanks for jumping in to the fray! None of my comments are blocking, so I believe the following is appropriate (if not s/Signed-off/Reviewed-by/). Signed-off-by: Will Drewry <wad@xxxxxxxxxxxx> cheers! will -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
