diff options
| -rw-r--r-- | fs/ext4/verity.c | 47 | ||||
| -rw-r--r-- | fs/f2fs/data.c | 2 | ||||
| -rw-r--r-- | fs/f2fs/f2fs.h | 3 | ||||
| -rw-r--r-- | fs/f2fs/verity.c | 47 | ||||
| -rw-r--r-- | fs/verity/enable.c | 67 | ||||
| -rw-r--r-- | fs/verity/fsverity_private.h | 17 | ||||
| -rw-r--r-- | fs/verity/hash_algs.c | 98 | ||||
| -rw-r--r-- | fs/verity/open.c | 5 | ||||
| -rw-r--r-- | fs/verity/verify.c | 47 | ||||
| -rw-r--r-- | include/linux/fsverity.h | 7 |
10 files changed, 273 insertions, 67 deletions
diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c index d0d8a9795dd6..dc5ec724d889 100644 --- a/fs/ext4/verity.c +++ b/fs/ext4/verity.c @@ -342,12 +342,55 @@ static int ext4_get_verity_descriptor(struct inode *inode, void *buf, return desc_size; } +/* + * Prefetch some pages from the file's Merkle tree. + * + * This is basically a stripped-down version of __do_page_cache_readahead() + * which works on pages past i_size. + */ +static void ext4_merkle_tree_readahead(struct address_space *mapping, + pgoff_t start_index, unsigned long count) +{ + LIST_HEAD(pages); + unsigned int nr_pages = 0; + struct page *page; + pgoff_t index; + struct blk_plug plug; + + for (index = start_index; index < start_index + count; index++) { + page = xa_load(&mapping->i_pages, index); + if (!page || xa_is_value(page)) { + page = __page_cache_alloc(readahead_gfp_mask(mapping)); + if (!page) + break; + page->index = index; + list_add(&page->lru, &pages); + nr_pages++; + } + } + blk_start_plug(&plug); + ext4_mpage_readpages(mapping, &pages, NULL, nr_pages, true); + blk_finish_plug(&plug); +} + static struct page *ext4_read_merkle_tree_page(struct inode *inode, - pgoff_t index) + pgoff_t index, + unsigned long num_ra_pages) { + struct page *page; + index += ext4_verity_metadata_pos(inode) >> PAGE_SHIFT; - return read_mapping_page(inode->i_mapping, index, NULL); + page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED); + if (!page || !PageUptodate(page)) { + if (page) + put_page(page); + else if (num_ra_pages > 1) + ext4_merkle_tree_readahead(inode->i_mapping, index, + num_ra_pages); + page = read_mapping_page(inode->i_mapping, index, NULL); + } + return page; } static int ext4_write_merkle_tree_block(struct inode *inode, const void *buf, diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index a034cd0ce021..0fa356e94ef5 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -1881,7 +1881,7 @@ out: * use ->readpage() or do the necessary surgery to decouple ->readpages() * from read-ahead. */ -static int f2fs_mpage_readpages(struct address_space *mapping, +int f2fs_mpage_readpages(struct address_space *mapping, struct list_head *pages, struct page *page, unsigned nr_pages, bool is_readahead) { diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 5a888a063c7f..059ade83bfb1 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -3229,6 +3229,9 @@ int f2fs_reserve_new_block(struct dnode_of_data *dn); int f2fs_get_block(struct dnode_of_data *dn, pgoff_t index); int f2fs_preallocate_blocks(struct kiocb *iocb, struct iov_iter *from); int f2fs_reserve_block(struct dnode_of_data *dn, pgoff_t index); +int f2fs_mpage_readpages(struct address_space *mapping, + struct list_head *pages, struct page *page, + unsigned nr_pages, bool is_readahead); struct page *f2fs_get_read_data_page(struct inode *inode, pgoff_t index, int op_flags, bool for_write); struct page *f2fs_find_data_page(struct inode *inode, pgoff_t index); diff --git a/fs/f2fs/verity.c b/fs/f2fs/verity.c index a401ef72bc82..d7d430a6f130 100644 --- a/fs/f2fs/verity.c +++ b/fs/f2fs/verity.c @@ -222,12 +222,55 @@ static int f2fs_get_verity_descriptor(struct inode *inode, void *buf, return size; } +/* + * Prefetch some pages from the file's Merkle tree. + * + * This is basically a stripped-down version of __do_page_cache_readahead() + * which works on pages past i_size. + */ +static void f2fs_merkle_tree_readahead(struct address_space *mapping, + pgoff_t start_index, unsigned long count) +{ + LIST_HEAD(pages); + unsigned int nr_pages = 0; + struct page *page; + pgoff_t index; + struct blk_plug plug; + + for (index = start_index; index < start_index + count; index++) { + page = xa_load(&mapping->i_pages, index); + if (!page || xa_is_value(page)) { + page = __page_cache_alloc(readahead_gfp_mask(mapping)); + if (!page) + break; + page->index = index; + list_add(&page->lru, &pages); + nr_pages++; + } + } + blk_start_plug(&plug); + f2fs_mpage_readpages(mapping, &pages, NULL, nr_pages, true); + blk_finish_plug(&plug); +} + static struct page *f2fs_read_merkle_tree_page(struct inode *inode, - pgoff_t index) + pgoff_t index, + unsigned long num_ra_pages) { + struct page *page; + index += f2fs_verity_metadata_pos(inode) >> PAGE_SHIFT; - return read_mapping_page(inode->i_mapping, index, NULL); + page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED); + if (!page || !PageUptodate(page)) { + if (page) + put_page(page); + else if (num_ra_pages > 1) + f2fs_merkle_tree_readahead(inode->i_mapping, index, + num_ra_pages); + page = read_mapping_page(inode->i_mapping, index, NULL); + } + return page; } static int f2fs_write_merkle_tree_block(struct inode *inode, const void *buf, diff --git a/fs/verity/enable.c b/fs/verity/enable.c index b79e3fd19d11..d98bea308fd7 100644 --- a/fs/verity/enable.c +++ b/fs/verity/enable.c @@ -8,18 +8,48 @@ #include "fsverity_private.h" #include <crypto/hash.h> +#include <linux/backing-dev.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/sched/signal.h> #include <linux/uaccess.h> -static int build_merkle_tree_level(struct inode *inode, unsigned int level, +/* + * Read a file data page for Merkle tree construction. Do aggressive readahead, + * since we're sequentially reading the entire file. + */ +static struct page *read_file_data_page(struct file *filp, pgoff_t index, + struct file_ra_state *ra, + unsigned long remaining_pages) +{ + struct page *page; + + page = find_get_page_flags(filp->f_mapping, index, FGP_ACCESSED); + if (!page || !PageUptodate(page)) { + if (page) + put_page(page); + else + page_cache_sync_readahead(filp->f_mapping, ra, filp, + index, remaining_pages); + page = read_mapping_page(filp->f_mapping, index, NULL); + if (IS_ERR(page)) + return page; + } + if (PageReadahead(page)) + page_cache_async_readahead(filp->f_mapping, ra, filp, page, + index, remaining_pages); + return page; +} + +static int build_merkle_tree_level(struct file *filp, unsigned int level, u64 num_blocks_to_hash, const struct merkle_tree_params *params, u8 *pending_hashes, struct ahash_request *req) { + struct inode *inode = file_inode(filp); const struct fsverity_operations *vops = inode->i_sb->s_vop; + struct file_ra_state ra = { 0 }; unsigned int pending_size = 0; u64 dst_block_num; u64 i; @@ -36,6 +66,8 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, dst_block_num = 0; /* unused */ } + file_ra_state_init(&ra, filp->f_mapping); + for (i = 0; i < num_blocks_to_hash; i++) { struct page *src_page; @@ -45,7 +77,8 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, if (level == 0) { /* Leaf: hashing a data block */ - src_page = read_mapping_page(inode->i_mapping, i, NULL); + src_page = read_file_data_page(filp, i, &ra, + num_blocks_to_hash - i); if (IS_ERR(src_page)) { err = PTR_ERR(src_page); fsverity_err(inode, @@ -54,9 +87,14 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, return err; } } else { + unsigned long num_ra_pages = + min_t(unsigned long, num_blocks_to_hash - i, + inode->i_sb->s_bdi->io_pages); + /* Non-leaf: hashing hash block from level below */ src_page = vops->read_merkle_tree_page(inode, - params->level_start[level - 1] + i); + params->level_start[level - 1] + i, + num_ra_pages); if (IS_ERR(src_page)) { err = PTR_ERR(src_page); fsverity_err(inode, @@ -103,17 +141,18 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, } /* - * Build the Merkle tree for the given inode using the given parameters, and + * Build the Merkle tree for the given file using the given parameters, and * return the root hash in @root_hash. * * The tree is written to a filesystem-specific location as determined by the * ->write_merkle_tree_block() method. However, the blocks that comprise the * tree are the same for all filesystems. */ -static int build_merkle_tree(struct inode *inode, +static int build_merkle_tree(struct file *filp, const struct merkle_tree_params *params, u8 *root_hash) { + struct inode *inode = file_inode(filp); u8 *pending_hashes; struct ahash_request *req; u64 blocks; @@ -126,9 +165,11 @@ static int build_merkle_tree(struct inode *inode, return 0; } + /* This allocation never fails, since it's mempool-backed. */ + req = fsverity_alloc_hash_request(params->hash_alg, GFP_KERNEL); + pending_hashes = kmalloc(params->block_size, GFP_KERNEL); - req = ahash_request_alloc(params->hash_alg->tfm, GFP_KERNEL); - if (!pending_hashes || !req) + if (!pending_hashes) goto out; /* @@ -139,7 +180,7 @@ static int build_merkle_tree(struct inode *inode, blocks = (inode->i_size + params->block_size - 1) >> params->log_blocksize; for (level = 0; level <= params->num_levels; level++) { - err = build_merkle_tree_level(inode, level, blocks, params, + err = build_merkle_tree_level(filp, level, blocks, params, pending_hashes, req); if (err) goto out; @@ -150,7 +191,7 @@ static int build_merkle_tree(struct inode *inode, err = 0; out: kfree(pending_hashes); - ahash_request_free(req); + fsverity_free_hash_request(params->hash_alg, req); return err; } @@ -175,8 +216,7 @@ static int enable_verity(struct file *filp, /* Get the salt if the user provided one */ if (arg->salt_size && - copy_from_user(desc->salt, - (const u8 __user *)(uintptr_t)arg->salt_ptr, + copy_from_user(desc->salt, u64_to_user_ptr(arg->salt_ptr), arg->salt_size)) { err = -EFAULT; goto out; @@ -185,8 +225,7 @@ static int enable_verity(struct file *filp, /* Get the signature if the user provided one */ if (arg->sig_size && - copy_from_user(desc->signature, - (const u8 __user *)(uintptr_t)arg->sig_ptr, + copy_from_user(desc->signature, u64_to_user_ptr(arg->sig_ptr), arg->sig_size)) { err = -EFAULT; goto out; @@ -227,7 +266,7 @@ static int enable_verity(struct file *filp, */ pr_debug("Building Merkle tree...\n"); BUILD_BUG_ON(sizeof(desc->root_hash) < FS_VERITY_MAX_DIGEST_SIZE); - err = build_merkle_tree(inode, ¶ms, desc->root_hash); + err = build_merkle_tree(filp, ¶ms, desc->root_hash); if (err) { fsverity_err(inode, "Error %d building Merkle tree", err); goto rollback; diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index e74c79b64d88..74768cf539da 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -16,6 +16,7 @@ #include <crypto/sha.h> #include <linux/fsverity.h> +#include <linux/mempool.h> struct ahash_request; @@ -37,11 +38,12 @@ struct fsverity_hash_alg { const char *name; /* crypto API name, e.g. sha256 */ unsigned int digest_size; /* digest size in bytes, e.g. 32 for SHA-256 */ unsigned int block_size; /* block size in bytes, e.g. 64 for SHA-256 */ + mempool_t req_pool; /* mempool with a preallocated hash request */ }; /* Merkle tree parameters: hash algorithm, initial hash state, and topology */ struct merkle_tree_params { - const struct fsverity_hash_alg *hash_alg; /* the hash algorithm */ + struct fsverity_hash_alg *hash_alg; /* the hash algorithm */ const u8 *hashstate; /* initial hash state or NULL */ unsigned int digest_size; /* same as hash_alg->digest_size */ unsigned int block_size; /* size of data and tree blocks */ @@ -50,6 +52,7 @@ struct merkle_tree_params { unsigned int log_arity; /* log2(hashes_per_block) */ unsigned int num_levels; /* number of levels in Merkle tree */ u64 tree_size; /* Merkle tree size in bytes */ + unsigned long level0_blocks; /* number of blocks in tree level 0 */ /* * Starting block index for each tree level, ordered from leaf level (0) @@ -114,14 +117,18 @@ struct fsverity_signed_digest { extern struct fsverity_hash_alg fsverity_hash_algs[]; -const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, - unsigned int num); -const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg, +struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, + unsigned int num); +struct ahash_request *fsverity_alloc_hash_request(struct fsverity_hash_alg *alg, + gfp_t gfp_flags); +void fsverity_free_hash_request(struct fsverity_hash_alg *alg, + struct ahash_request *req); +const u8 *fsverity_prepare_hash_state(struct fsverity_hash_alg *alg, const u8 *salt, size_t salt_size); int fsverity_hash_page(const struct merkle_tree_params *params, const struct inode *inode, struct ahash_request *req, struct page *page, u8 *out); -int fsverity_hash_buffer(const struct fsverity_hash_alg *alg, +int fsverity_hash_buffer(struct fsverity_hash_alg *alg, const void *data, size_t size, u8 *out); void __init fsverity_check_hash_algs(void); diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c index 31e6d7d2389a..c37e186ebeb6 100644 --- a/fs/verity/hash_algs.c +++ b/fs/verity/hash_algs.c @@ -24,6 +24,8 @@ struct fsverity_hash_alg fsverity_hash_algs[] = { }, }; +static DEFINE_MUTEX(fsverity_hash_alg_init_mutex); + /** * fsverity_get_hash_alg() - validate and prepare a hash algorithm * @inode: optional inode for logging purposes @@ -36,8 +38,8 @@ struct fsverity_hash_alg fsverity_hash_algs[] = { * * Return: pointer to the hash alg on success, else an ERR_PTR() */ -const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, - unsigned int num) +struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, + unsigned int num) { struct fsverity_hash_alg *alg; struct crypto_ahash *tfm; @@ -50,10 +52,15 @@ const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, } alg = &fsverity_hash_algs[num]; - /* pairs with cmpxchg() below */ - tfm = READ_ONCE(alg->tfm); - if (likely(tfm != NULL)) + /* pairs with smp_store_release() below */ + if (likely(smp_load_acquire(&alg->tfm) != NULL)) return alg; + + mutex_lock(&fsverity_hash_alg_init_mutex); + + if (alg->tfm != NULL) + goto out_unlock; + /* * Using the shash API would make things a bit simpler, but the ahash * API is preferable as it allows the use of crypto accelerators. @@ -64,12 +71,14 @@ const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, fsverity_warn(inode, "Missing crypto API support for hash algorithm \"%s\"", alg->name); - return ERR_PTR(-ENOPKG); + alg = ERR_PTR(-ENOPKG); + goto out_unlock; } fsverity_err(inode, "Error allocating hash algorithm \"%s\": %ld", alg->name, PTR_ERR(tfm)); - return ERR_CAST(tfm); + alg = ERR_CAST(tfm); + goto out_unlock; } err = -EINVAL; @@ -78,18 +87,61 @@ const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, if (WARN_ON(alg->block_size != crypto_ahash_blocksize(tfm))) goto err_free_tfm; + err = mempool_init_kmalloc_pool(&alg->req_pool, 1, + sizeof(struct ahash_request) + + crypto_ahash_reqsize(tfm)); + if (err) + goto err_free_tfm; + pr_info("%s using implementation \"%s\"\n", alg->name, crypto_ahash_driver_name(tfm)); - /* pairs with READ_ONCE() above */ - if (cmpxchg(&alg->tfm, NULL, tfm) != NULL) - crypto_free_ahash(tfm); - - return alg; + /* pairs with smp_load_acquire() above */ + smp_store_release(&alg->tfm, tfm); + goto out_unlock; err_free_tfm: crypto_free_ahash(tfm); - return ERR_PTR(err); + alg = ERR_PTR(err); +out_unlock: + mutex_unlock(&fsverity_hash_alg_init_mutex); + return alg; +} + +/** + * fsverity_alloc_hash_request() - allocate a hash request object + * @alg: the hash algorithm for which to allocate the request + * @gfp_flags: memory allocation flags + * + * This is mempool-backed, so this never fails if __GFP_DIRECT_RECLAIM is set in + * @gfp_flags. However, in that case this might need to wait for all + * previously-allocated requests to be freed. So to avoid deadlocks, callers + * must never need multiple requests at a time to make forward progress. + * + * Return: the request object on success; NULL on failure (but see above) + */ +struct ahash_request *fsverity_alloc_hash_request(struct fsverity_hash_alg *alg, + gfp_t gfp_flags) +{ + struct ahash_request *req = mempool_alloc(&alg->req_pool, gfp_flags); + + if (req) + ahash_request_set_tfm(req, alg->tfm); + return req; +} + +/** + * fsverity_free_hash_request() - free a hash request object + * @alg: the hash algorithm + * @req: the hash request object to free + */ +void fsverity_free_hash_request(struct fsverity_hash_alg *alg, + struct ahash_request *req) +{ + if (req) { + ahash_request_zero(req); + mempool_free(req, &alg->req_pool); + } } /** @@ -101,7 +153,7 @@ err_free_tfm: * Return: NULL if the salt is empty, otherwise the kmalloc()'ed precomputed * initial hash state on success or an ERR_PTR() on failure. */ -const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg, +const u8 *fsverity_prepare_hash_state(struct fsverity_hash_alg *alg, const u8 *salt, size_t salt_size) { u8 *hashstate = NULL; @@ -119,11 +171,8 @@ const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg, if (!hashstate) return ERR_PTR(-ENOMEM); - req = ahash_request_alloc(alg->tfm, GFP_KERNEL); - if (!req) { - err = -ENOMEM; - goto err_free; - } + /* This allocation never fails, since it's mempool-backed. */ + req = fsverity_alloc_hash_request(alg, GFP_KERNEL); /* * Zero-pad the salt to the next multiple of the input size of the hash @@ -158,7 +207,7 @@ const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg, if (err) goto err_free; out: - ahash_request_free(req); + fsverity_free_hash_request(alg, req); kfree(padded_salt); return hashstate; @@ -229,7 +278,7 @@ int fsverity_hash_page(const struct merkle_tree_params *params, * * Return: 0 on success, -errno on failure */ -int fsverity_hash_buffer(const struct fsverity_hash_alg *alg, +int fsverity_hash_buffer(struct fsverity_hash_alg *alg, const void *data, size_t size, u8 *out) { struct ahash_request *req; @@ -237,9 +286,8 @@ int fsverity_hash_buffer(const struct fsverity_hash_alg *alg, DECLARE_CRYPTO_WAIT(wait); int err; - req = ahash_request_alloc(alg->tfm, GFP_KERNEL); - if (!req) - return -ENOMEM; + /* This allocation never fails, since it's mempool-backed. */ + req = fsverity_alloc_hash_request(alg, GFP_KERNEL); sg_init_one(&sg, data, size); ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | @@ -249,7 +297,7 @@ int fsverity_hash_buffer(const struct fsverity_hash_alg *alg, err = crypto_wait_req(crypto_ahash_digest(req), &wait); - ahash_request_free(req); + fsverity_free_hash_request(alg, req); return err; } diff --git a/fs/verity/open.c b/fs/verity/open.c index 63d1004b688c..c5fe6948e262 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -31,7 +31,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, unsigned int log_blocksize, const u8 *salt, size_t salt_size) { - const struct fsverity_hash_alg *hash_alg; + struct fsverity_hash_alg *hash_alg; int err; u64 blocks; u64 offset; @@ -102,6 +102,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, /* temporarily using level_start[] to store blocks in level */ params->level_start[params->num_levels++] = blocks; } + params->level0_blocks = params->level_start[0]; /* Compute the starting block of each level */ offset = 0; @@ -126,7 +127,7 @@ out_err: * Compute the file measurement by hashing the fsverity_descriptor excluding the * signature and with the sig_size field set to 0. */ -static int compute_file_measurement(const struct fsverity_hash_alg *hash_alg, +static int compute_file_measurement(struct fsverity_hash_alg *hash_alg, struct fsverity_descriptor *desc, u8 *measurement) { diff --git a/fs/verity/verify.c b/fs/verity/verify.c index 3e8f2de44667..e0cb62da3864 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -84,7 +84,8 @@ static inline int cmp_hashes(const struct fsverity_info *vi, * Return: true if the page is valid, else false. */ static bool verify_page(struct inode *inode, const struct fsverity_info *vi, - struct ahash_request *req, struct page *data_page) + struct ahash_request *req, struct page *data_page, + unsigned long level0_ra_pages) { const struct merkle_tree_params *params = &vi->tree_params; const unsigned int hsize = params->digest_size; @@ -117,8 +118,8 @@ static bool verify_page(struct inode *inode, const struct fsverity_info *vi, pr_debug_ratelimited("Level %d: hindex=%lu, hoffset=%u\n", level, hindex, hoffset); - hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, - hindex); + hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, hindex, + level == 0 ? level0_ra_pages : 0); if (IS_ERR(hpage)) { err = PTR_ERR(hpage); fsverity_err(inode, @@ -191,13 +192,12 @@ bool fsverity_verify_page(struct page *page) struct ahash_request *req; bool valid; - req = ahash_request_alloc(vi->tree_params.hash_alg->tfm, GFP_NOFS); - if (unlikely(!req)) - return false; + /* This allocation never fails, since it's mempool-backed. */ + req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS); - valid = verify_page(inode, vi, req, page); + valid = verify_page(inode, vi, req, page, 0); - ahash_request_free(req); + fsverity_free_hash_request(vi->tree_params.hash_alg, req); return valid; } @@ -222,25 +222,42 @@ void fsverity_verify_bio(struct bio *bio) { struct inode *inode = bio_first_page_all(bio)->mapping->host; const struct fsverity_info *vi = inode->i_verity_info; + const struct merkle_tree_params *params = &vi->tree_params; struct ahash_request *req; struct bio_vec *bv; struct bvec_iter_all iter_all; - - req = ahash_request_alloc(vi->tree_params.hash_alg->tfm, GFP_NOFS); - if (unlikely(!req)) { + unsigned long max_ra_pages = 0; + + /* This allocation never fails, since it's mempool-backed. */ + req = fsverity_alloc_hash_request(params->hash_alg, GFP_NOFS); + + if (bio->bi_opf & REQ_RAHEAD) { + /* + * If this bio is for data readahead, then we also do readahead + * of the first (largest) level of the Merkle tree. Namely, + * when a Merkle tree page is read, we also try to piggy-back on + * some additional pages -- up to 1/4 the number of data pages. + * + * This improves sequential read performance, as it greatly + * reduces the number of I/O requests made to the Merkle tree. + */ bio_for_each_segment_all(bv, bio, iter_all) - SetPageError(bv->bv_page); - return; + max_ra_pages++; + max_ra_pages /= 4; } bio_for_each_segment_all(bv, bio, iter_all) { struct page *page = bv->bv_page; + unsigned long level0_index = page->index >> params->log_arity; + unsigned long level0_ra_pages = + min(max_ra_pages, params->level0_blocks - level0_index); - if (!PageError(page) && !verify_page(inode, vi, req, page)) + if (!PageError(page) && + !verify_page(inode, vi, req, page, level0_ra_pages)) SetPageError(page); } - ahash_request_free(req); + fsverity_free_hash_request(params->hash_alg, req); } EXPORT_SYMBOL_GPL(fsverity_verify_bio); #endif /* CONFIG_BLOCK */ diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 3b6b8ccebe7d..ecc604e61d61 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -77,6 +77,10 @@ struct fsverity_operations { * * @inode: the inode * @index: 0-based index of the page within the Merkle tree + * @num_ra_pages: The number of Merkle tree pages that should be + * prefetched starting at @index if the page at @index + * isn't already cached. Implementations may ignore this + * argument; it's only a performance optimization. * * This can be called at any time on an open verity file, as well as * between ->begin_enable_verity() and ->end_enable_verity(). It may be @@ -87,7 +91,8 @@ struct fsverity_operations { * Return: the page on success, ERR_PTR() on failure */ struct page *(*read_merkle_tree_page)(struct inode *inode, - pgoff_t index); + pgoff_t index, + unsigned long num_ra_pages); /** * Write a Merkle tree block to the given inode. |