From: Qu Wenruo wqu@suse.com
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@wdc.com Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -202,11 +202,9 @@ 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);
@@ -217,7 +215,7 @@ 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)) @@ -3210,7 +3208,7 @@ 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 @@ -52,6 +52,8 @@ 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 @@ -2501,6 +2501,7 @@ 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. */ @@ -2515,6 +2516,21 @@ 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)