[PATCH 7/9] Validate input arguments to libfsverity_compute_digest()

[Jes Sorensen <jes.sorensen@xxxxxxxxx>]

From: Jes Sorensen <jsorensen@xxxxxx>

If any argument is invalid, return -EINVAL. Similarly
if any of the reserved fields in the params struct
are set, return -EINVAL;

Signed-off-by: Jes Sorensen <jsorensen@xxxxxx>
---
 libverity.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/libverity.c b/libverity.c
index 183259e..1cef544 100644
--- a/libverity.c
+++ b/libverity.c
@@ -155,9 +155,31 @@ libfsverity_compute_digest(int fd,
 	struct fsverity_descriptor desc;
 	struct stat stbuf;
 	u64 file_size;
-	int retval = -EINVAL;
+	int i, retval = -EINVAL;
+
+	if (!digest_ret)
+		return -EINVAL;
+	if (params->version != 1)
+		return -EINVAL;
+	if (!is_power_of_2(params->block_size))
+		return -EINVAL;
+	if (params->salt_size > sizeof(desc.salt)) {
+		error_msg("Salt too long (got %u bytes; max is %zu bytes)",
+			  params->salt_size, sizeof(desc.salt));
+		return -EINVAL;
+	}
+	if (params->salt_size && !params->salt)
+		return -EINVAL;
+	for (i = 0;
+	     i < sizeof(params->reserved) / sizeof(params->reserved[0]); i++) {
+		if (params->reserved[i])
+			return -EINVAL;
+	}
 
 	hash_alg = libfsverity_find_hash_alg_by_num(params->hash_algorithm);
+	if (!hash_alg)
+		return -EINVAL;
+
 	hash = hash_alg->create_ctx(hash_alg);
 
 	digest = malloc(sizeof(struct libfsverity_digest) +
@@ -180,16 +202,9 @@ libfsverity_compute_digest(int fd,
 	desc.version = 1;
 	desc.hash_algorithm = params->hash_algorithm;
 
-	ASSERT(is_power_of_2(params->block_size));
 	desc.log_blocksize = ilog2(params->block_size);
 
 	if (params->salt_size != 0) {
-		if (params->salt_size > sizeof(desc.salt)) {
-			error_msg("Salt too long (got %u bytes; max is %zu bytes)",
-				  params->salt_size, sizeof(desc.salt));
-			retval = EINVAL;
-			goto error_out;
-		}
 		memcpy(desc.salt, params->salt, params->salt_size);
 		desc.salt_size = params->salt_size;
 	}
-- 
2.24.1