From: Eric Biggers <ebigg...@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 <ebigg...@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



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