From: Qu Wenruo <wqu@xxxxxxxx>
commit 3d17adea74a56a4965f7a603d8ed8c66bb9356d9 upstream.
Previous commit a05d3c915314 ("btrfs: check superblock to ensure the fs
was not modified at thaw time") only checks the content of the super
block, but it doesn't really check if the on-disk super block has a
matching checksum.
This patch will add the checksum verification to thaw time superblock
verification.
This involves the following extra changes:
- Export btrfs_check_super_csum()
As we need to call it in super.c.
- Change the argument list of btrfs_check_super_csum()
Instead of passing a char *, directly pass struct btrfs_super_block *
pointer.
- Verify that our checksum type didn't change before checking the
checksum value, like it's done at mount time
Fixes: a05d3c915314 ("btrfs: check superblock to ensure the fs was not modified at thaw time")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/disk-io.c | 10 ++++------
fs/btrfs/disk-io.h | 2 ++
fs/btrfs/super.c | 16 ++++++++++++++++
3 files changed, 22 insertions(+), 6 deletions(-)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -167,11 +167,9 @@ static bool btrfs_supported_super_csum(u
* Return 0 if the superblock checksum type matches the checksum value of that
* algorithm. Pass the raw disk superblock data.
*/
-static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
- char *raw_disk_sb)
+int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
+ const struct btrfs_super_block *disk_sb)
{
- struct btrfs_super_block *disk_sb =
- (struct btrfs_super_block *)raw_disk_sb;
char result[BTRFS_CSUM_SIZE];
SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
@@ -182,7 +180,7 @@ static int btrfs_check_super_csum(struct
* BTRFS_SUPER_INFO_SIZE range, we expect that the unused space is
* filled with zeros and is included in the checksum.
*/
- crypto_shash_digest(shash, raw_disk_sb + BTRFS_CSUM_SIZE,
+ crypto_shash_digest(shash, (const u8 *)disk_sb + BTRFS_CSUM_SIZE,
BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE, result);
if (memcmp(disk_sb->csum, result, fs_info->csum_size))
@@ -3471,7 +3469,7 @@ int __cold open_ctree(struct super_block
* We want to check superblock checksum, the type is stored inside.
* Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
*/
- if (btrfs_check_super_csum(fs_info, (u8 *)disk_super)) {
+ if (btrfs_check_super_csum(fs_info, disk_super)) {
btrfs_err(fs_info, "superblock checksum mismatch");
err = -EINVAL;
btrfs_release_disk_super(disk_super);
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -42,6 +42,8 @@ struct extent_buffer *btrfs_find_create_
void btrfs_clean_tree_block(struct extent_buffer *buf);
void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info);
int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info);
+int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
+ const struct btrfs_super_block *disk_sb);
int __cold open_ctree(struct super_block *sb,
struct btrfs_fs_devices *fs_devices,
char *options);
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2553,6 +2553,7 @@ static int check_dev_super(struct btrfs_
{
struct btrfs_fs_info *fs_info = dev->fs_info;
struct btrfs_super_block *sb;
+ u16 csum_type;
int ret = 0;
/* This should be called with fs still frozen. */
@@ -2567,6 +2568,21 @@ static int check_dev_super(struct btrfs_
if (IS_ERR(sb))
return PTR_ERR(sb);
+ /* Verify the checksum. */
+ csum_type = btrfs_super_csum_type(sb);
+ if (csum_type != btrfs_super_csum_type(fs_info->super_copy)) {
+ btrfs_err(fs_info, "csum type changed, has %u expect %u",
+ csum_type, btrfs_super_csum_type(fs_info->super_copy));
+ ret = -EUCLEAN;
+ goto out;
+ }
+
+ if (btrfs_check_super_csum(fs_info, sb)) {
+ btrfs_err(fs_info, "csum for on-disk super block no longer matches");
+ ret = -EUCLEAN;
+ goto out;
+ }
+
/* Btrfs_validate_super() includes fsid check against super->fsid. */
ret = btrfs_validate_super(fs_info, sb, 0);
if (ret < 0)
