Commit 579a12f7 authored Dec 23, 2022 by Eric Biggers

fsverity: store log2(digest_size) precomputed



Add log_digestsize to struct merkle_tree_params so that it can be used
in verify.c.  Also save memory by using u8 for all the log_* fields.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Andrey Albershteyn <aalbersh@redhat.com>
Tested-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://lore.kernel.org/r/20221223203638.41293-4-ebiggers@kernel.org

parent 9098f36b

fs/verity/fsverity_private.h

+3 −2

Original line number	Diff line number	Diff line
		@@ -42,8 +42,9 @@ struct merkle_tree_params {
		unsigned int digest_size; /* same as hash_alg->digest_size */
		unsigned int block_size; /* size of data and tree blocks */
		unsigned int hashes_per_block; /* number of hashes per tree block */
		unsigned int log_blocksize; /* log2(block_size) */
		unsigned int log_arity; /* log2(hashes_per_block) */
		u8 log_digestsize; /* log2(digest_size) */
		u8 log_blocksize; /* log2(block_size) */
		u8 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 tree_pages; /* Merkle tree size in pages */

fs/verity/open.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -76,7 +76,8 @@ int fsverity_init_merkle_tree_params(struct merkle_tree_params *params,
		err = -EINVAL;
		goto out_err;
		}
		params->log_arity = params->log_blocksize - ilog2(params->digest_size);
		params->log_digestsize = ilog2(params->digest_size);
		params->log_arity = log_blocksize - params->log_digestsize;
		params->hashes_per_block = 1 << params->log_arity;

		/*

fs/verity/verify.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -35,7 +35,7 @@ static void hash_at_level(const struct merkle_tree_params *params,

		/* Offset of the wanted hash (in bytes) within the hash block */
		*hoffset = (position & ((1 << params->log_arity) - 1)) <<
		(params->log_blocksize - params->log_arity);
		params->log_digestsize;
		}

		static inline int cmp_hashes(const struct fsverity_info *vi,