[PATCH] image-host: refactor and protect for very long filenames

[Hugo Cornelis]

This patch adds a function fit_image_read_key_iv_data that checks the
return value of snprintf and allows to generate a sensible error
message when generating binary images using filenames that are too
long for the OS to handle.

This is especially relevant for automated builds such as Buildroot and
Yocto builds.

Signed-off-by: Hugo Cornelis <hugo.cornelis at essensium.com>
---
 tools/image-host.c | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

diff --git a/tools/image-host.c b/tools/image-host.c
index ca4950312f..0092fa830f 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -340,6 +340,28 @@ err:
 	return ret;
 }
 
+static int fit_image_read_key_iv_data(const char *keydir, const char *key_iv_name,
+				      unsigned char *key_iv_data, int expected_size)
+{
+	char filename[PATH_MAX];
+	int ret = -1;
+
+	ret = snprintf(filename, sizeof(filename), "%s/%s%s",
+		       keydir, key_iv_name, ".bin");
+	if (ret >= sizeof(filename)) {
+		printf("Can't format the key or IV filename when setting up the cipher: insufficient buffer space\n");
+		ret = -1;
+	}
+	if (ret < 0) {
+		printf("Can't format the key or IV filename when setting up the cipher: snprintf error\n");
+		ret = -1;
+	}
+
+	ret = fit_image_read_data(filename, key_iv_data, expected_size);
+
+	return ret;
+}
+
 static int get_random_data(void *data, int size)
 {
 	unsigned char *tmp = data;
@@ -376,7 +398,6 @@ static int fit_image_setup_cipher(struct image_cipher_info *info,
 				  int noffset)
 {
 	char *algo_name;
-	char filename[128];
 	int ret = -1;
 
 	if (fit_image_cipher_get_algo(fit, noffset, &algo_name)) {
@@ -413,17 +434,17 @@ static int fit_image_setup_cipher(struct image_cipher_info *info,
 		goto out;
 	}
 
-	/* Read the key in the file */
-	snprintf(filename, sizeof(filename), "%s/%s%s",
-		 info->keydir, info->keyname, ".bin");
 	info->key = malloc(info->cipher->key_len);
 	if (!info->key) {
 		fprintf(stderr, "Can't allocate memory for key\n");
 		ret = -1;
 		goto out;
 	}
-	ret = fit_image_read_data(filename, (unsigned char *)info->key,
-				  info->cipher->key_len);
+
+	/* Read the key in the file */
+	ret = fit_image_read_key_iv_data(info->keydir, info->keyname,
+					 (unsigned char *)info->key,
+					 info->cipher->key_len);
 	if (ret < 0)
 		goto out;
 
@@ -436,10 +457,11 @@ static int fit_image_setup_cipher(struct image_cipher_info *info,
 
 	if (info->ivname) {
 		/* Read the IV in the file */
-		snprintf(filename, sizeof(filename), "%s/%s%s",
-			 info->keydir, info->ivname, ".bin");
-		ret = fit_image_read_data(filename, (unsigned char *)info->iv,
-					  info->cipher->iv_len);
+		ret = fit_image_read_key_iv_data(info->keydir, info->ivname,
+						 (unsigned char *)info->iv,
+						 info->cipher->iv_len);
+		if (ret < 0)
+			goto out;
 	} else {
 		/* Generate an ramdom IV */
 		ret = get_random_data((void *)info->iv, info->cipher->iv_len);
-- 
2.34.1