libblkid: cramfs: add checksum support

diff --git a/libblkid/src/superblocks/cramfs.c b/libblkid/src/superblocks/cramfs.c
index 2c41cc5deb325f7a93adc6be1b08f5baea63752e..fd893fc1880bb70e548ea66c5594797969005318 100644 (file)
--- 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;
 }