libblkid: erofs: add checksum support

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>

diff --git a/libblkid/src/superblocks/erofs.c b/libblkid/src/superblocks/erofs.c
index 30914a89c4f8a183a487cae5a03fbe028c80e234..a914704156cf63bb078669364160c7752347d414 100644 (file)
--- a/libblkid/src/superblocks/erofs.c
+++ b/libblkid/src/superblocks/erofs.c
@@ -8,9 +8,11 @@
 #include <string.h>
 
 #include "superblocks.h"
+#include "crc32c.h"
 
 #define EROFS_SUPER_OFFSET      1024
 #define EROFS_SB_KBOFF         (EROFS_SUPER_OFFSET >> 10)
+#define EROFS_FEATURE_SB_CSUM  (1 << 0)
 
 #define EROFS_SUPER_MAGIC_V1   "\xe2\xe1\xf5\xe0"
 #define EROFS_MAGIC_OFF                0
@@ -37,6 +39,25 @@ struct erofs_super_block {
        uint8_t         reserved2[44];
 };
 
+static int erofs_verify_checksum(blkid_probe pr, const struct blkid_idmag *mag,
+               const struct erofs_super_block *sb)
+{
+       if (!(le32_to_cpu(sb->feature_compat) & EROFS_FEATURE_SB_CSUM))
+               return 1;
+
+       uint32_t expected = le32_to_cpu(sb->checksum);
+
+       size_t csummed_size = (1U << sb->blkszbits) - EROFS_SUPER_OFFSET;
+       unsigned char *csummed = blkid_probe_get_sb_buffer(pr, mag, csummed_size);
+       if (!csummed)
+               return 0;
+
+       memset(csummed + offsetof(struct erofs_super_block, checksum), 0, sizeof(uint32_t));
+       uint32_t csum = crc32c(~0L, csummed, csummed_size);
+
+       return blkid_probe_verify_csum(pr, csum, expected);
+}
+
 static int probe_erofs(blkid_probe pr, const struct blkid_idmag *mag)
 {
        struct erofs_super_block *sb;
@@ -45,6 +66,9 @@ static int probe_erofs(blkid_probe pr, const struct blkid_idmag *mag)
        if (!sb)
                return errno ? -errno : BLKID_PROBE_NONE;
 
+       if (!erofs_verify_checksum(pr, mag, sb))
+               return BLKID_PROBE_NONE;
+
        if (sb->volume_name[0])
                blkid_probe_set_label(pr, (unsigned char *)sb->volume_name,
                                      sizeof(sb->volume_name));