From 13e2408d02dd12a3b46bf8a29b3ae4f6119fc520 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Sat, 3 Jun 2023 19:23:12 -0700 Subject: [PATCH] fsverity: simplify error handling in verify_data_block() Clean up the error handling in verify_data_block() to (a) eliminate the 'err' variable which has caused some confusion because the function actually returns a bool, (b) reduce the compiled code size slightly, and (c) execute one fewer branch in the success case. Link: https://lore.kernel.org/r/20230604022312.48532-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- fs/verity/verify.c | 55 +++++++++++++++++++++--------------------------------- 1 file changed, 21 insertions(+), 34 deletions(-) diff --git a/fs/verity/verify.c b/fs/verity/verify.c index cf40e2f..433cef5 100644 --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -12,23 +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; -} - /* * Returns true if the hash block with index @hblock_idx in the tree, located in * @hpage, has already been verified. @@ -131,7 +114,6 @@ 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); @@ -191,11 +173,10 @@ verify_data_block(struct inode *inode, struct fsverity_info *vi, 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)) { @@ -221,12 +202,10 @@ descend: unsigned long hblock_idx = hblocks[level - 1].index; unsigned int hoffset = hblocks[level - 1].hoffset; - err = fsverity_hash_block(params, inode, haddr, 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 @@ -243,16 +222,24 @@ descend: } /* Finally, verify the data block. */ - err = fsverity_hash_block(params, inode, data, real_hash); - if (err) - goto out; - err = cmp_hashes(vi, want_hash, real_hash, data_pos, -1); -out: + if (fsverity_hash_block(params, inode, data, real_hash) != 0) + goto error; + if (memcmp(want_hash, real_hash, hsize) != 0) + goto corrupted; + return true; + +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 err == 0; + return false; } static bool -- 2.7.4