Btrfs-progs will read the superblock without checking the checksum.
When all superblocks are corrupted, continuing will cause disaster.
So this patch will add checksum check for btrfs-progs when reading
superblocks.
Also fix a bug that btrfs_read_dev_super() only reads sizeof(struct
btrfs_super_block), corrent size should be BTRFS_SUPER_INFO_SIZE.
Signed-off-by: Qu Wenruo <quwen...@cn.fujitsu.com>
---
v2:
Use corrent memcmp src.
Read the whole supblock size(sectorsize) other than
sizeof(btrfs_super_block).
---
disk-io.c | 46 +++++++++++++++++++++++++++++-----------------
1 file changed, 29 insertions(+), 17 deletions(-)
diff --git a/disk-io.c b/disk-io.c
index 8db0335..e447af8 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -1186,22 +1186,25 @@ int btrfs_read_dev_super(int fd, struct
btrfs_super_block *sb, u64 sb_bytenr)
{
u8 fsid[BTRFS_FSID_SIZE];
int fsid_is_initialized = 0;
- struct btrfs_super_block buf;
+ u8 data[BTRFS_SUPER_INFO_SIZE];
+ struct btrfs_super_block *buf = (struct btrfs_super_block *) data;
int i;
int ret;
u64 transid = 0;
u64 bytenr;
+ u32 crc;
+ char crc_result[BTRFS_CSUM_SIZE];
if (sb_bytenr != BTRFS_SUPER_INFO_OFFSET) {
- ret = pread64(fd, &buf, sizeof(buf), sb_bytenr);
- if (ret < sizeof(buf))
+ ret = pread64(fd, data, sizeof(data), sb_bytenr);
+ if (ret < sizeof(data))
return -1;
- if (btrfs_super_bytenr(&buf) != sb_bytenr ||
- btrfs_super_magic(&buf) != BTRFS_MAGIC)
+ if (btrfs_super_bytenr(buf) != sb_bytenr ||
+ btrfs_super_magic(buf) != BTRFS_MAGIC)
return -1;
- memcpy(sb, &buf, sizeof(*sb));
+ memcpy(sb, data, sizeof(data));
return 0;
}
@@ -1214,22 +1217,31 @@ int btrfs_read_dev_super(int fd, struct
btrfs_super_block *sb, u64 sb_bytenr)
for (i = 0; i < 1; i++) {
bytenr = btrfs_sb_offset(i);
- ret = pread64(fd, &buf, sizeof(buf), bytenr);
- if (ret < sizeof(buf))
+ ret = pread64(fd, data, sizeof(data), bytenr);
+ if (ret < sizeof(data))
break;
- if (btrfs_super_bytenr(&buf) != bytenr )
+ if (btrfs_super_bytenr(buf) != bytenr)
continue;
- /* if magic is NULL, the device was removed */
- if (btrfs_super_magic(&buf) == 0 && i == 0)
+ /* if first super block is not btrfs, the device was removed */
+ if (btrfs_super_magic(buf) != BTRFS_MAGIC && i == 0)
return -1;
- if (btrfs_super_magic(&buf) != BTRFS_MAGIC)
+ if (btrfs_super_magic(buf) != BTRFS_MAGIC)
+ continue;
+
+ /* check if the superblock is damaged */
+ crc = ~(u32)0;
+ crc = btrfs_csum_data(NULL, (char *)buf + BTRFS_CSUM_SIZE,
+ crc, BTRFS_SUPER_INFO_SIZE -
+ BTRFS_CSUM_SIZE);
+ btrfs_csum_final(crc, crc_result);
+ if (memcmp(crc_result, buf, btrfs_super_csum_size(buf)))
continue;
if (!fsid_is_initialized) {
- memcpy(fsid, buf.fsid, sizeof(fsid));
+ memcpy(fsid, buf->fsid, sizeof(fsid));
fsid_is_initialized = 1;
- } else if (memcmp(fsid, buf.fsid, sizeof(fsid))) {
+ } else if (memcmp(fsid, buf->fsid, sizeof(fsid))) {
/*
* the superblocks (the original one and
* its backups) contain data of different
@@ -1238,9 +1250,9 @@ int btrfs_read_dev_super(int fd, struct btrfs_super_block
*sb, u64 sb_bytenr)
continue;
}
- if (btrfs_super_generation(&buf) > transid) {
- memcpy(sb, &buf, sizeof(*sb));
- transid = btrfs_super_generation(&buf);
+ if (btrfs_super_generation(buf) > transid) {
+ memcpy(sb, data, sizeof(data));
+ transid = btrfs_super_generation(buf);
}
}
--
2.0.1
--
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