From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Thu, 13 Oct 2022 22:33:54 +0000 (+0200)
Subject: libblkid: cramfs: add checksum support
X-Git-Tag: v2.39-rc1~482^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3703ce084235a92b8b1c143bef3089c8b3e022b9;p=thirdparty%2Futil-linux.git

libblkid: cramfs: add checksum support
---

diff --git a/libblkid/src/superblocks/cramfs.c b/libblkid/src/superblocks/cramfs.c
index 2c41cc5deb..fd893fc188 100644
--- a/libblkid/src/superblocks/cramfs.c
+++ b/libblkid/src/superblocks/cramfs.c
@@ -16,6 +16,7 @@
 #include <stdint.h>
 
 #include "superblocks.h"
+#include "crc32.h"
 
 struct cramfs_super
 {
@@ -34,6 +35,24 @@ struct cramfs_super
 	uint8_t		name[16];
 } __attribute__((packed));
 
+#define CRAMFS_FLAG_FSID_VERSION_2	0x00000001	/* fsid version #2 */
+
+static int cramfs_verify_csum(blkid_probe pr, const struct blkid_idmag *mag, struct cramfs_super *cs)
+{
+	if (!(cs->flags & CRAMFS_FLAG_FSID_VERSION_2))
+		return 1;
+
+	uint32_t expected = le32_to_cpu(cs->info.crc);
+	uint32_t csummed_size = le32_to_cpu(cs->size);
+	if (csummed_size > 1 << 16)
+		return 0;
+
+	unsigned char *csummed = blkid_probe_get_sb_buffer(pr, mag, csummed_size);
+	memset(csummed + offsetof(struct cramfs_super, info.crc), 0, sizeof(uint32_t));
+	uint32_t crc = ~ul_crc32(~0LL, csummed, csummed_size);
+	return blkid_probe_verify_csum(pr, crc, expected);
+}
+
 static int probe_cramfs(blkid_probe pr, const struct blkid_idmag *mag)
 {
 	struct cramfs_super *cs;
@@ -42,6 +61,9 @@ static int probe_cramfs(blkid_probe pr, const struct blkid_idmag *mag)
 	if (!cs)
 		return errno ? -errno : 1;
 
+	if (!cramfs_verify_csum(pr, mag, cs))
+		return 1;
+
 	blkid_probe_set_label(pr, cs->name, sizeof(cs->name));
 	return 0;
 }