fs-verity: add SHA-512 support

Add SHA-512 support to fs-verity.  This is primarily a demonstration of
the trivial changes needed to support a new hash algorithm in fs-verity;
most users will still use SHA-256, due to the smaller space required to
store the hashes.  But some users may prefer SHA-512.

Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>

diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h
index eaa2b3b..02a547f 100644 (file)
--- a/fs/verity/fsverity_private.h
+++ b/fs/verity/fsverity_private.h
@@ -29,7 +29,7 @@ struct ahash_request;
  * Largest digest size among all hash algorithms supported by fs-verity.
  * Currently assumed to be <= size of fsverity_descriptor::root_hash.
  */
-#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 7df1d67..31e6d7d 100644 (file)
--- a/fs/verity/hash_algs.c
+++ b/fs/verity/hash_algs.c
@@ -17,6 +17,11 @@ struct fsverity_hash_alg fsverity_hash_algs[] = {
                .digest_size = SHA256_DIGEST_SIZE,
                .block_size = SHA256_BLOCK_SIZE,
        },
+       [FS_VERITY_HASH_ALG_SHA512] = {
+               .name = "sha512",
+               .digest_size = SHA512_DIGEST_SIZE,
+               .block_size = SHA512_BLOCK_SIZE,
+       },
 };
 
 /**

diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h
index 57d1d7f..da0daf6 100644 (file)
--- a/include/uapi/linux/fsverity.h
+++ b/include/uapi/linux/fsverity.h
@@ -14,6 +14,7 @@
 #include <linux/types.h>
 
 #define FS_VERITY_HASH_ALG_SHA256      1
+#define FS_VERITY_HASH_ALG_SHA512      2
 
 struct fsverity_enable_arg {
        __u32 version;