diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/verity/Kconfig | 16 | ||||
| -rw-r--r-- | fs/verity/enable.c | 21 | ||||
| -rw-r--r-- | fs/verity/fsverity_private.h | 23 | ||||
| -rw-r--r-- | fs/verity/hash_algs.c | 139 | ||||
| -rw-r--r-- | fs/verity/measure.c | 37 | ||||
| -rw-r--r-- | fs/verity/open.c | 12 | ||||
| -rw-r--r-- | fs/verity/read_metadata.c | 4 | ||||
| -rw-r--r-- | fs/verity/signature.c | 8 | ||||
| -rw-r--r-- | fs/verity/verify.c | 164 |
9 files changed, 152 insertions, 272 deletions
diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig index a7ffd718f171..e1036e535352 100644 --- a/fs/verity/Kconfig +++ b/fs/verity/Kconfig @@ -39,14 +39,14 @@ config FS_VERITY_BUILTIN_SIGNATURES depends on FS_VERITY select SYSTEM_DATA_VERIFICATION help - Support verifying signatures of verity files against the X.509 - certificates that have been loaded into the ".fs-verity" - kernel keyring. + This option adds support for in-kernel verification of + fs-verity builtin signatures. - This is meant as a relatively simple mechanism that can be - used to provide an authenticity guarantee for verity files, as - an alternative to IMA appraisal. Userspace programs still - need to check that the verity bit is set in order to get an - authenticity guarantee. + Please take great care before using this feature. It is not + the only way to do signatures with fs-verity, and the + alternatives (such as userspace signature verification, and + IMA appraisal) can be much better. For details about the + limitations of this feature, see + Documentation/filesystems/fsverity.rst. If unsure, say N. diff --git a/fs/verity/enable.c b/fs/verity/enable.c index fc4c50e5219d..c284f46d1b53 100644 --- a/fs/verity/enable.c +++ b/fs/verity/enable.c @@ -7,6 +7,7 @@ #include "fsverity_private.h" +#include <crypto/hash.h> #include <linux/mount.h> #include <linux/sched/signal.h> #include <linux/uaccess.h> @@ -20,7 +21,7 @@ struct block_buffer { /* Hash a block, writing the result to the next level's pending block buffer. */ static int hash_one_block(struct inode *inode, const struct merkle_tree_params *params, - struct ahash_request *req, struct block_buffer *cur) + struct block_buffer *cur) { struct block_buffer *next = cur + 1; int err; @@ -36,8 +37,7 @@ static int hash_one_block(struct inode *inode, /* Zero-pad the block if it's shorter than the block size. */ memset(&cur->data[cur->filled], 0, params->block_size - cur->filled); - err = fsverity_hash_block(params, inode, req, virt_to_page(cur->data), - offset_in_page(cur->data), + err = fsverity_hash_block(params, inode, cur->data, &next->data[next->filled]); if (err) return err; @@ -76,7 +76,6 @@ static int build_merkle_tree(struct file *filp, struct inode *inode = file_inode(filp); const u64 data_size = inode->i_size; const int num_levels = params->num_levels; - struct ahash_request *req; struct block_buffer _buffers[1 + FS_VERITY_MAX_LEVELS + 1] = {}; struct block_buffer *buffers = &_buffers[1]; unsigned long level_offset[FS_VERITY_MAX_LEVELS]; @@ -90,9 +89,6 @@ static int build_merkle_tree(struct file *filp, return 0; } - /* This allocation never fails, since it's mempool-backed. */ - req = fsverity_alloc_hash_request(params->hash_alg, GFP_KERNEL); - /* * Allocate the block buffers. Buffer "-1" is for data blocks. * Buffers 0 <= level < num_levels are for the actual tree levels. @@ -130,7 +126,7 @@ static int build_merkle_tree(struct file *filp, fsverity_err(inode, "Short read of file data"); goto out; } - err = hash_one_block(inode, params, req, &buffers[-1]); + err = hash_one_block(inode, params, &buffers[-1]); if (err) goto out; for (level = 0; level < num_levels; level++) { @@ -141,8 +137,7 @@ static int build_merkle_tree(struct file *filp, } /* Next block at @level is full */ - err = hash_one_block(inode, params, req, - &buffers[level]); + err = hash_one_block(inode, params, &buffers[level]); if (err) goto out; err = write_merkle_tree_block(inode, @@ -162,8 +157,7 @@ static int build_merkle_tree(struct file *filp, /* Finish all nonempty pending tree blocks. */ for (level = 0; level < num_levels; level++) { if (buffers[level].filled != 0) { - err = hash_one_block(inode, params, req, - &buffers[level]); + err = hash_one_block(inode, params, &buffers[level]); if (err) goto out; err = write_merkle_tree_block(inode, @@ -183,7 +177,6 @@ static int build_merkle_tree(struct file *filp, out: for (level = -1; level < num_levels; level++) kfree(buffers[level].data); - fsverity_free_hash_request(params->hash_alg, req); return err; } @@ -215,7 +208,7 @@ static int enable_verity(struct file *filp, } desc->salt_size = arg->salt_size; - /* Get the signature if the user provided one */ + /* Get the builtin signature if the user provided one */ if (arg->sig_size && copy_from_user(desc->signature, u64_to_user_ptr(arg->sig_ptr), arg->sig_size)) { diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index d34dcc033d72..49bf3a1eb2a0 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -11,9 +11,6 @@ #define pr_fmt(fmt) "fs-verity: " fmt #include <linux/fsverity.h> -#include <linux/mempool.h> - -struct ahash_request; /* * Implementation limit: maximum depth of the Merkle tree. For now 8 is plenty; @@ -23,11 +20,10 @@ struct ahash_request; /* A hash algorithm supported by fs-verity */ struct fsverity_hash_alg { - struct crypto_ahash *tfm; /* hash tfm, allocated on demand */ + struct crypto_shash *tfm; /* hash tfm, allocated on demand */ 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 */ /* * The HASH_ALGO_* constant for this algorithm. This is different from * FS_VERITY_HASH_ALG_*, which uses a different numbering scheme. @@ -37,7 +33,7 @@ struct fsverity_hash_alg { /* Merkle tree parameters: hash algorithm, initial hash state, and topology */ struct merkle_tree_params { - struct fsverity_hash_alg *hash_alg; /* the hash algorithm */ + const 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 */ @@ -83,18 +79,13 @@ struct fsverity_info { extern struct fsverity_hash_alg fsverity_hash_algs[]; -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 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, const u8 *salt, size_t salt_size); int fsverity_hash_block(const struct merkle_tree_params *params, - const struct inode *inode, struct ahash_request *req, - struct page *page, unsigned int offset, u8 *out); -int fsverity_hash_buffer(struct fsverity_hash_alg *alg, + const struct inode *inode, const void *data, u8 *out); +int fsverity_hash_buffer(const 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 ea00dbedf756..c598d2035476 100644 --- a/fs/verity/hash_algs.c +++ b/fs/verity/hash_algs.c @@ -8,7 +8,6 @@ #include "fsverity_private.h" #include <crypto/hash.h> -#include <linux/scatterlist.h> /* The hash algorithms supported by fs-verity */ struct fsverity_hash_alg fsverity_hash_algs[] = { @@ -40,11 +39,11 @@ static DEFINE_MUTEX(fsverity_hash_alg_init_mutex); * * Return: pointer to the hash alg on success, else an ERR_PTR() */ -struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, - unsigned int num) +const struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, + unsigned int num) { struct fsverity_hash_alg *alg; - struct crypto_ahash *tfm; + struct crypto_shash *tfm; int err; if (num >= ARRAY_SIZE(fsverity_hash_algs) || @@ -63,11 +62,7 @@ struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, 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. - */ - tfm = crypto_alloc_ahash(alg->name, 0, 0); + tfm = crypto_alloc_shash(alg->name, 0, 0); if (IS_ERR(tfm)) { if (PTR_ERR(tfm) == -ENOENT) { fsverity_warn(inode, @@ -84,26 +79,20 @@ struct fsverity_hash_alg *fsverity_get_hash_alg(const struct inode *inode, } err = -EINVAL; - if (WARN_ON_ONCE(alg->digest_size != crypto_ahash_digestsize(tfm))) + if (WARN_ON_ONCE(alg->digest_size != crypto_shash_digestsize(tfm))) goto err_free_tfm; - if (WARN_ON_ONCE(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) + if (WARN_ON_ONCE(alg->block_size != crypto_shash_blocksize(tfm))) goto err_free_tfm; pr_info("%s using implementation \"%s\"\n", - alg->name, crypto_ahash_driver_name(tfm)); + alg->name, crypto_shash_driver_name(tfm)); /* pairs with smp_load_acquire() above */ smp_store_release(&alg->tfm, tfm); goto out_unlock; err_free_tfm: - crypto_free_ahash(tfm); + crypto_free_shash(tfm); alg = ERR_PTR(err); out_unlock: mutex_unlock(&fsverity_hash_alg_init_mutex); @@ -111,42 +100,6 @@ out_unlock: } /** - * 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); - } -} - -/** * fsverity_prepare_hash_state() - precompute the initial hash state * @alg: hash algorithm * @salt: a salt which is to be prepended to all data to be hashed @@ -155,27 +108,24 @@ void fsverity_free_hash_request(struct fsverity_hash_alg *alg, * 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(struct fsverity_hash_alg *alg, +const u8 *fsverity_prepare_hash_state(const struct fsverity_hash_alg *alg, const u8 *salt, size_t salt_size) { u8 *hashstate = NULL; - struct ahash_request *req = NULL; + SHASH_DESC_ON_STACK(desc, alg->tfm); u8 *padded_salt = NULL; size_t padded_salt_size; - struct scatterlist sg; - DECLARE_CRYPTO_WAIT(wait); int err; + desc->tfm = alg->tfm; + if (salt_size == 0) return NULL; - hashstate = kmalloc(crypto_ahash_statesize(alg->tfm), GFP_KERNEL); + hashstate = kmalloc(crypto_shash_statesize(alg->tfm), GFP_KERNEL); if (!hashstate) return ERR_PTR(-ENOMEM); - /* 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 * algorithm's compression function, e.g. 64 bytes for SHA-256 or 128 @@ -190,26 +140,18 @@ const u8 *fsverity_prepare_hash_state(struct fsverity_hash_alg *alg, goto err_free; } memcpy(padded_salt, salt, salt_size); - - sg_init_one(&sg, padded_salt, padded_salt_size); - ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | - CRYPTO_TFM_REQ_MAY_BACKLOG, - crypto_req_done, &wait); - ahash_request_set_crypt(req, &sg, NULL, padded_salt_size); - - err = crypto_wait_req(crypto_ahash_init(req), &wait); + err = crypto_shash_init(desc); if (err) goto err_free; - err = crypto_wait_req(crypto_ahash_update(req), &wait); + err = crypto_shash_update(desc, padded_salt, padded_salt_size); if (err) goto err_free; - err = crypto_ahash_export(req, hashstate); + err = crypto_shash_export(desc, hashstate); if (err) goto err_free; out: - fsverity_free_hash_request(alg, req); kfree(padded_salt); return hashstate; @@ -223,9 +165,7 @@ err_free: * fsverity_hash_block() - hash a single data or hash block * @params: the Merkle tree's parameters * @inode: inode for which the hashing is being done - * @req: preallocated hash request - * @page: the page containing the block to hash - * @offset: the offset of the block within @page + * @data: virtual address of a buffer containing the block to hash * @out: output digest, size 'params->digest_size' bytes * * Hash a single data or hash block. The hash is salted if a salt is specified @@ -234,33 +174,24 @@ err_free: * Return: 0 on success, -errno on failure */ int fsverity_hash_block(const struct merkle_tree_params *params, - const struct inode *inode, struct ahash_request *req, - struct page *page, unsigned int offset, u8 *out) + const struct inode *inode, const void *data, u8 *out) { - struct scatterlist sg; - DECLARE_CRYPTO_WAIT(wait); + SHASH_DESC_ON_STACK(desc, params->hash_alg->tfm); int err; - sg_init_table(&sg, 1); - sg_set_page(&sg, page, params->block_size, offset); - ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | - CRYPTO_TFM_REQ_MAY_BACKLOG, - crypto_req_done, &wait); - ahash_request_set_crypt(req, &sg, out, params->block_size); + desc->tfm = params->hash_alg->tfm; if (params->hashstate) { - err = crypto_ahash_import(req, params->hashstate); + err = crypto_shash_import(desc, params->hashstate); if (err) { fsverity_err(inode, "Error %d importing hash state", err); return err; } - err = crypto_ahash_finup(req); + err = crypto_shash_finup(desc, data, params->block_size, out); } else { - err = crypto_ahash_digest(req); + err = crypto_shash_digest(desc, data, params->block_size, out); } - - err = crypto_wait_req(err, &wait); if (err) fsverity_err(inode, "Error %d computing block hash", err); return err; @@ -273,32 +204,12 @@ int fsverity_hash_block(const struct merkle_tree_params *params, * @size: size of data to hash, in bytes * @out: output digest, size 'alg->digest_size' bytes * - * Hash some data which is located in physically contiguous memory (i.e. memory - * allocated by kmalloc(), not by vmalloc()). No salt is used. - * * Return: 0 on success, -errno on failure */ -int fsverity_hash_buffer(struct fsverity_hash_alg *alg, +int fsverity_hash_buffer(const struct fsverity_hash_alg *alg, const void *data, size_t size, u8 *out) { - struct ahash_request *req; - struct scatterlist sg; - DECLARE_CRYPTO_WAIT(wait); - int err; - - /* 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 | - CRYPTO_TFM_REQ_MAY_BACKLOG, - crypto_req_done, &wait); - ahash_request_set_crypt(req, &sg, out, size); - - err = crypto_wait_req(crypto_ahash_digest(req), &wait); - - fsverity_free_hash_request(alg, req); - return err; + return crypto_shash_tfm_digest(alg->tfm, data, size, out); } void __init fsverity_check_hash_algs(void) diff --git a/fs/verity/measure.c b/fs/verity/measure.c index 5c79ea1b2468..eec5956141da 100644 --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -61,27 +61,42 @@ EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); /** * fsverity_get_digest() - get a verity file's digest * @inode: inode to get digest of - * @digest: (out) pointer to the digest - * @alg: (out) pointer to the hash algorithm enumeration + * @raw_digest: (out) the raw file digest + * @alg: (out) the digest's algorithm, as a FS_VERITY_HASH_ALG_* value + * @halg: (out) the digest's algorithm, as a HASH_ALGO_* value * - * Return the file hash algorithm and digest of an fsverity protected file. - * Assumption: before calling this, the file must have been opened. + * Retrieves the fsverity digest of the given file. The file must have been + * opened at least once since the inode was last loaded into the inode cache; + * otherwise this function will not recognize when fsverity is enabled. * - * Return: 0 on success, -errno on failure + * The file's fsverity digest consists of @raw_digest in combination with either + * @alg or @halg. (The caller can choose which one of @alg or @halg to use.) + * + * IMPORTANT: Callers *must* make use of one of the two algorithm IDs, since + * @raw_digest is meaningless without knowing which algorithm it uses! fsverity + * provides no security guarantee for users who ignore the algorithm ID, even if + * they use the digest size (since algorithms can share the same digest size). + * + * Return: The size of the raw digest in bytes, or 0 if the file doesn't have + * fsverity enabled. */ int fsverity_get_digest(struct inode *inode, - u8 digest[FS_VERITY_MAX_DIGEST_SIZE], - enum hash_algo *alg) + u8 raw_digest[FS_VERITY_MAX_DIGEST_SIZE], + u8 *alg, enum hash_algo *halg) { const struct fsverity_info *vi; const struct fsverity_hash_alg *hash_alg; vi = fsverity_get_info(inode); if (!vi) - return -ENODATA; /* not a verity file */ + return 0; /* not a verity file */ hash_alg = vi->tree_params.hash_alg; - memcpy(digest, vi->file_digest, hash_alg->digest_size); - *alg = hash_alg->algo_id; - return 0; + memcpy(raw_digest, vi->file_digest, hash_alg->digest_size); + if (alg) + *alg = hash_alg - fsverity_hash_algs; + if (halg) + *halg = hash_alg->algo_id; + return hash_alg->digest_size; } +EXPORT_SYMBOL_GPL(fsverity_get_digest); diff --git a/fs/verity/open.c b/fs/verity/open.c index 52048b7630dc..1db5106a9c38 100644 --- a/fs/verity/open.c +++ b/fs/verity/open.c @@ -32,7 +32,7 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params, unsigned int log_blocksize, const u8 *salt, size_t salt_size) { - struct fsverity_hash_alg *hash_alg; + const struct fsverity_hash_alg *hash_alg; int err; u64 blocks; u64 blocks_in_level[FS_VERITY_MAX_LEVELS]; @@ -156,9 +156,9 @@ out_err: /* * Compute the file digest by hashing the fsverity_descriptor excluding the - * signature and with the sig_size field set to 0. + * builtin signature and with the sig_size field set to 0. */ -static int compute_file_digest(struct fsverity_hash_alg *hash_alg, +static int compute_file_digest(const struct fsverity_hash_alg *hash_alg, struct fsverity_descriptor *desc, u8 *file_digest) { @@ -174,7 +174,7 @@ static int compute_file_digest(struct fsverity_hash_alg *hash_alg, /* * Create a new fsverity_info from the given fsverity_descriptor (with optional - * appended signature), and check the signature if present. The + * appended builtin signature), and check the signature if present. The * fsverity_descriptor must have already undergone basic validation. */ struct fsverity_info *fsverity_create_info(const struct inode *inode, @@ -319,8 +319,8 @@ static bool validate_fsverity_descriptor(struct inode *inode, } /* - * Read the inode's fsverity_descriptor (with optional appended signature) from - * the filesystem, and do basic validation of it. + * Read the inode's fsverity_descriptor (with optional appended builtin + * signature) from the filesystem, and do basic validation of it. */ int fsverity_get_descriptor(struct inode *inode, struct fsverity_descriptor **desc_ret) diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c index 2aefc5565152..f58432772d9e 100644 --- a/fs/verity/read_metadata.c +++ b/fs/verity/read_metadata.c @@ -105,7 +105,7 @@ static int fsverity_read_descriptor(struct inode *inode, if (res) return res; - /* don't include the signature */ + /* don't include the builtin signature */ desc_size = offsetof(struct fsverity_descriptor, signature); desc->sig_size = 0; @@ -131,7 +131,7 @@ static int fsverity_read_signature(struct inode *inode, } /* - * Include only the signature. Note that fsverity_get_descriptor() + * Include only the builtin signature. fsverity_get_descriptor() * already verified that sig_size is in-bounds. */ res = fsverity_read_buffer(buf, offset, length, desc->signature, diff --git a/fs/verity/signature.c b/fs/verity/signature.c index b8c51ad40d3a..72034bc71c9d 100644 --- a/fs/verity/signature.c +++ b/fs/verity/signature.c @@ -5,6 +5,14 @@ * Copyright 2019 Google LLC */ +/* + * This file implements verification of fs-verity builtin signatures. Please + * take great care before using this feature. It is not the only way to do + * signatures with fs-verity, and the alternatives (such as userspace signature + * verification, and IMA appraisal) can be much better. For details about the + * limitations of this feature, see Documentation/filesystems/fsverity.rst. + */ + #include "fsverity_private.h" #include <linux/cred.h> diff --git a/fs/verity/verify.c b/fs/verity/verify.c index e2508222750b..433cef51f5f6 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -12,38 +12,6 @@ static struct workqueue_struct *fsverity_read_workqueue; -static inline int cmp_hashes(const struct fsverity_info *vi, - const u8 *want_hash, const u8 *real_hash, - u64 data_pos, int level) -{ - const unsigned int hsize = vi->tree_params.digest_size; - - if (memcmp(want_hash, real_hash, hsize) == 0) - return 0; - - fsverity_err(vi->inode, - "FILE CORRUPTED! pos=%llu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN", - data_pos, level, - vi->tree_params.hash_alg->name, hsize, want_hash, - vi->tree_params.hash_alg->name, hsize, real_hash); - return -EBADMSG; -} - -static bool data_is_zeroed(struct inode *inode, struct page *page, - unsigned int len, unsigned int offset) -{ - void *virt = kmap_local_page(page); - - if (memchr_inv(virt + offset, 0, len)) { - kunmap_local(virt); - fsverity_err(inode, - "FILE CORRUPTED! Data past EOF is not zeroed"); - return false; - } - kunmap_local(virt); - return true; -} - /* * Returns true if the hash block with index @hblock_idx in the tree, located in * @hpage, has already been verified. @@ -122,9 +90,7 @@ static bool is_hash_block_verified(struct fsverity_info *vi, struct page *hpage, */ static bool verify_data_block(struct inode *inode, struct fsverity_info *vi, - struct ahash_request *req, struct page *data_page, - u64 data_pos, unsigned int dblock_offset_in_page, - unsigned long max_ra_pages) + const void *data, u64 data_pos, unsigned long max_ra_pages) { const struct merkle_tree_params *params = &vi->tree_params; const unsigned int hsize = params->digest_size; @@ -136,11 +102,11 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, struct { /* Page containing the hash block */ struct page *page; + /* Mapped address of the hash block (will be within @page) */ + const void *addr; /* Index of the hash block in the tree overall */ unsigned long index; - /* Byte offset of the hash block within @page */ - unsigned int offset_in_page; - /* Byte offset of the wanted hash within @page */ + /* Byte offset of the wanted hash relative to @addr */ unsigned int hoffset; } hblocks[FS_VERITY_MAX_LEVELS]; /* @@ -148,7 +114,9 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, * index of that block's hash within the current level. */ u64 hidx = data_pos >> params->log_blocksize; - int err; + + /* Up to 1 + FS_VERITY_MAX_LEVELS pages may be mapped at once */ + BUILD_BUG_ON(1 + FS_VERITY_MAX_LEVELS > KM_MAX_IDX); if (unlikely(data_pos >= inode->i_size)) { /* @@ -159,8 +127,12 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, * any part past EOF should be all zeroes. Therefore, we need * to verify that any data blocks fully past EOF are all zeroes. */ - return data_is_zeroed(inode, data_page, params->block_size, - dblock_offset_in_page); + if (memchr_inv(data, 0, params->block_size)) { + fsverity_err(inode, + "FILE CORRUPTED! Data past EOF is not zeroed"); + return false; + } + return true; } /* @@ -175,6 +147,7 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, unsigned int hblock_offset_in_page; unsigned int hoffset; struct page *hpage; + const void *haddr; /* * The index of the block in the current level; also the index @@ -192,30 +165,30 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, hblock_offset_in_page = (hblock_idx << params->log_blocksize) & ~PAGE_MASK; - /* Byte offset of the hash within the page */ - hoffset = hblock_offset_in_page + - ((hidx << params->log_digestsize) & - (params->block_size - 1)); + /* Byte offset of the hash within the block */ + hoffset = (hidx << params->log_digestsize) & + (params->block_size - 1); hpage = inode->i_sb->s_vop->read_merkle_tree_page(inode, hpage_idx, level == 0 ? min(max_ra_pages, params->tree_pages - hpage_idx) : 0); if (IS_ERR(hpage)) { - err = PTR_ERR(hpage); fsverity_err(inode, - "Error %d reading Merkle tree page %lu", - err, hpage_idx); - goto out; + "Error %ld reading Merkle tree page %lu", + PTR_ERR(hpage), hpage_idx); + goto error; } + haddr = kmap_local_page(hpage) + hblock_offset_in_page; if (is_hash_block_verified(vi, hpage, hblock_idx)) { - memcpy_from_page(_want_hash, hpage, hoffset, hsize); + memcpy(_want_hash, haddr + hoffset, hsize); want_hash = _want_hash; + kunmap_local(haddr); put_page(hpage); goto descend; } hblocks[level].page = hpage; + hblocks[level].addr = haddr; hblocks[level].index = hblock_idx; - hblocks[level].offset_in_page = hblock_offset_in_page; hblocks[level].hoffset = hoffset; hidx = next_hidx; } @@ -225,18 +198,14 @@ descend: /* Descend the tree verifying hash blocks. */ for (; level > 0; level--) { struct page *hpage = hblocks[level - 1].page; + const void *haddr = hblocks[level - 1].addr; unsigned long hblock_idx = hblocks[level - 1].index; - unsigned int hblock_offset_in_page = - hblocks[level - 1].offset_in_page; unsigned int hoffset = hblocks[level - 1].hoffset; - err = fsverity_hash_block(params, inode, req, hpage, - hblock_offset_in_page, real_hash); - if (err) - goto out; - err = cmp_hashes(vi, want_hash, real_hash, data_pos, level - 1); - if (err) - goto out; + if (fsverity_hash_block(params, inode, haddr, real_hash) != 0) + goto error; + if (memcmp(want_hash, real_hash, hsize) != 0) + goto corrupted; /* * Mark the hash block as verified. This must be atomic and * idempotent, as the same hash block might be verified by @@ -246,29 +215,39 @@ descend: set_bit(hblock_idx, vi->hash_block_verified); else SetPageChecked(hpage); - memcpy_from_page(_want_hash, hpage, hoffset, hsize); + memcpy(_want_hash, haddr + hoffset, hsize); want_hash = _want_hash; + kunmap_local(haddr); put_page(hpage); } /* Finally, verify the data block. */ - err = fsverity_hash_block(params, inode, req, data_page, - dblock_offset_in_page, real_hash); - if (err) - goto out; - err = cmp_hashes(vi, want_hash, real_hash, data_pos, -1); -out: - for (; level > 0; level--) - put_page(hblocks[level - 1].page); + if (fsverity_hash_block(params, inode, data, real_hash) != 0) + goto error; + if (memcmp(want_hash, real_hash, hsize) != 0) + goto corrupted; + return true; - return err == 0; +corrupted: + fsverity_err(inode, + "FILE CORRUPTED! pos=%llu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN", + data_pos, level - 1, + params->hash_alg->name, hsize, want_hash, + params->hash_alg->name, hsize, real_hash); +error: + for (; level > 0; level--) { + kunmap_local(hblocks[level - 1].addr); + put_page(hblocks[level - 1].page); + } + return false; } static bool -verify_data_blocks(struct inode *inode, struct fsverity_info *vi, - struct ahash_request *req, struct folio *data_folio, - size_t len, size_t offset, unsigned long max_ra_pages) +verify_data_blocks(struct folio *data_folio, size_t len, size_t offset, + unsigned long max_ra_pages) { + struct inode *inode = data_folio->mapping->host; + struct fsverity_info *vi = inode->i_verity_info; const unsigned int block_size = vi->tree_params.block_size; u64 pos = (u64)data_folio->index << PAGE_SHIFT; @@ -278,11 +257,14 @@ verify_data_blocks(struct inode *inode, struct fsverity_info *vi, folio_test_uptodate(data_folio))) return false; do { - struct page *data_page = - folio_page(data_folio, offset >> PAGE_SHIFT); - - if (!verify_data_block(inode, vi, req, data_page, pos + offset, - offset & ~PAGE_MASK, max_ra_pages)) + void *data; + bool valid; + + data = kmap_local_folio(data_folio, offset); + valid = verify_data_block(inode, vi, data, pos + offset, + max_ra_pages); + kunmap_local(data); + if (!valid) return false; offset += block_size; len -= block_size; @@ -304,19 +286,7 @@ verify_data_blocks(struct inode *inode, struct fsverity_info *vi, */ bool fsverity_verify_blocks(struct folio *folio, size_t len, size_t offset) { - struct inode *inode = folio->mapping->host; - struct fsverity_info *vi = inode->i_verity_info; - struct ahash_request *req; - bool valid; - - /* This allocation never fails, since it's mempool-backed. */ - req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS); - - valid = verify_data_blocks(inode, vi, req, folio, len, offset, 0); - - fsverity_free_hash_request(vi->tree_params.hash_alg, req); - - return valid; + return verify_data_blocks(folio, len, offset, 0); } EXPORT_SYMBOL_GPL(fsverity_verify_blocks); @@ -337,15 +307,9 @@ EXPORT_SYMBOL_GPL(fsverity_verify_blocks); */ void fsverity_verify_bio(struct bio *bio) { - struct inode *inode = bio_first_page_all(bio)->mapping->host; - struct fsverity_info *vi = inode->i_verity_info; - struct ahash_request *req; struct folio_iter fi; unsigned long max_ra_pages = 0; - /* This allocation never fails, since it's mempool-backed. */ - req = fsverity_alloc_hash_request(vi->tree_params.hash_alg, GFP_NOFS); - if (bio->bi_opf & REQ_RAHEAD) { /* * If this bio is for data readahead, then we also do readahead @@ -360,14 +324,12 @@ void fsverity_verify_bio(struct bio *bio) } bio_for_each_folio_all(fi, bio) { - if (!verify_data_blocks(inode, vi, req, fi.folio, fi.length, - fi.offset, max_ra_pages)) { + if (!verify_data_blocks(fi.folio, fi.length, fi.offset, + max_ra_pages)) { bio->bi_status = BLK_STS_IOERR; break; } } - - fsverity_free_hash_request(vi->tree_params.hash_alg, req); } EXPORT_SYMBOL_GPL(fsverity_verify_bio); #endif /* CONFIG_BLOCK */ |