[PATCH v2 07/12] fs-verity: add SHA-512 support

Eric Biggers
2018-11-01T22:54:58Z

From: Eric Biggers <ebiggers@google.com>

Add SHA-512 support to fs-verity. This is primarily a demonstration of
the (small) changes needed to support a new hash algorithm; it's
anticipated that most users will still prefer SHA-256 due to the smaller
space required to store the hashes, though some may prefer SHA-512.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
fs/verity/fsverity_private.h | 2 +-
fs/verity/hash_algs.c | 5 +++++
include/uapi/linux/fsverity.h | 1 +
3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
index dfdbac3874d74..c3a261a598557 100644
--- a/fs/verity/fsverity_private.h
+++ b/fs/verity/fsverity_private.h
@@ -30,7 +30,7 @@
* Largest digest size among all hash algorithms supported by fs-verity. This
* can be increased if needed.
*/
-#define FS_VERITY_MAX_DIGEST_SIZE SHA256_DIGEST_SIZE
+#define FS_VERITY_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE

/* A hash algorithm supported by fs-verity */
struct fsverity_hash_alg {
diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c
index 9c19c9553f120..3174a0c08785d 100644
--- a/fs/verity/hash_algs.c
+++ b/fs/verity/hash_algs.c
@@ -18,6 +18,11 @@ struct fsverity_hash_alg fsverity_hash_algs[] = {
.digest_size = 32,
.cryptographic = true,
},
+ [FS_VERITY_ALG_SHA512] = {
+ .name = "sha512",
+ .digest_size = 64,
+ .cryptographic = true,
+ },
};

/*
diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h
index 55b9f32676220..67ed830ae2ece 100644
--- a/include/uapi/linux/fsverity.h
+++ b/include/uapi/linux/fsverity.h
@@ -28,6 +28,7 @@ struct fsverity_digest {

/* Supported hash algorithms */
#define FS_VERITY_ALG_SHA256 1
+#define FS_VERITY_ALG_SHA512 2

/* Metadata stored near the end of verity files, after the Merkle tree */
/* This structure is 64 bytes long */
--
2.19.1.568.g152ad8e336-goog