[PATCH v3] kwboot: do a filetype check before sending the image

[Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>]

Signed-off-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
---
Changes since (implicit) v1, sent with
Message-Id: 1453276010-4669-1-git-send-email-uwe@xxxxxxxxxxxxxxxxx:

- whitespace fix
- error out if a problem is detected
- add a commit log

Changes since v2, sent with
Message-Id: 1453277701-10367-1-git-send-email-uwe@xxxxxxxxxxxxxxxxx:

- add -f to not quit on failed test
- add const to img parameter
- check image length first
- write error messages to stderr instead of stdout
- simplify logic

Thanks to Sascha, Sebastian and Trend for the feedback.

 scripts/kwboot.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 70 insertions(+), 2 deletions(-)

diff --git a/scripts/kwboot.c b/scripts/kwboot.c
index 46328d8ed006..9b0d1d0602a0 100644
--- a/scripts/kwboot.c
+++ b/scripts/kwboot.c
@@ -546,6 +546,63 @@ out:
 	return rc;
 }
 
+static int
+kwboot_check_image(const unsigned char *img, size_t size)
+{
+	size_t i;
+	size_t header_size, image_size;
+	unsigned char csum = 0;
+
+	if (size < 0x20) {
+		fprintf(stderr,
+			"Image too small to even contain a Main Header\n");
+		return 1;
+	}
+
+	switch (img[0x0]) {
+		case 0x5a: /* SPI/NOR */
+		case 0x69: /* UART0 */
+		case 0x78: /* SATA */
+		case 0x8b: /* NAND */
+		case 0x9c: /* PCIe */
+			break;
+		default:
+			fprintf(stderr,
+				"Unknown boot source: 0x%hhx\n", img[0x0]);
+			return 1;
+	}
+
+	if (img[0x8] != 1) {
+		fprintf(stderr, "Unknown version: 0x%hhx\n", img[0x8]);
+		return 1;
+	}
+
+	image_size = img[0x4] | (img[0x5] << 8) |
+		(img[0x6] << 16) | (img[0x7] << 24);
+
+	header_size = (img[0x9] << 16) | img[0xa] | (img[0xb] << 8);
+
+	if (header_size + image_size != size) {
+		fprintf(stderr, "Size mismatch (%zu + %zu != %zu)\n",
+			header_size, image_size, size);
+		return 1;
+	}
+
+	for (i = 0; i < header_size; ++i)
+		csum += img[i];
+
+	csum -= img[0x1f];
+
+	if (csum != img[0x1f]) {
+		fprintf(stderr,
+			"Checksum mismatch: specified: 0x%02hhx, calculated: 0x%02hhx\n",
+			img[0x1f], csum);
+		return 1;
+	}
+
+	return 0;
+}
+
 static void *
 kwboot_mmap_image(const char *path, size_t *size, int prot)
 {
@@ -608,7 +665,7 @@ int
 main(int argc, char **argv)
 {
 	const char *ttypath, *imgpath;
-	int rv, rc, tty, term;
+	int rv, rc, tty, term, force = 0;
 	void *bootmsg;
 	void *debugmsg;
 	void *img;
@@ -628,7 +685,7 @@ main(int argc, char **argv)
 	kwboot_verbose = isatty(STDOUT_FILENO);
 
 	do {
-		int c = getopt(argc, argv, "hb:dtB:D:");
+		int c = getopt(argc, argv, "b:dfhtB:D:");
 		if (c < 0)
 			break;
 
@@ -651,6 +708,10 @@ main(int argc, char **argv)
 			term = 1;
 			break;
 
+		case 'f':
+			force = 1;
+			break;
+
 		case 'B':
 			speed = kwboot_tty_speed(atoi(optarg));
 			if (speed == -1)
@@ -684,6 +745,13 @@ main(int argc, char **argv)
 			perror(imgpath);
 			goto out;
 		}
+
+		rc = kwboot_check_image(img, size);
+		if (rc && !force) {
+			fprintf(stderr,
+				"Image check failed, restart with -f to ignore\n");
+			goto out;
+		}
 	}
 
 	if (debugmsg) {
-- 
2.7.0.rc3


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