Re: [PATCH 5/6] btrfs: tree-checker: Verify inode item

[Nikolay Borisov <nborisov@suse.com>]

On 13.03.19 г. 10:55 ч., Qu Wenruo wrote:
> There is a report in kernel bugzilla about mismatch file type in dir
> item and inode item.
> 
> This inspires us to check inode mode in inode item.
> 
> This patch will check the following members:
> - inode key objectid
>   Should be ROOT_DIR_DIR or [256, (u64)-256] or FREE_INO.
> 
> - inode key offset
>   Should be 0
> 
> - inode item generation
> - inode item transid
>   No newer than sb generation + 1.
>   The +1 is for log tree.
> 
> - inode item mode
>   No unknown bits.
>   No invalid S_IF* bit.
>   NOTE: S_IFMT check is not enough, need extra check for it.
> 
> - inode item nlink
>   Dir should have no more link than 1.
> 
> - inode item flags
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/btrfs/ctree.h        |  2 +
>  fs/btrfs/tree-checker.c | 99 +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 101 insertions(+)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 7a2a2621f0d9..f002c63a34e3 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1504,6 +1504,8 @@ do {                                                                   \
>  #define BTRFS_INODE_COMPRESS		(1 << 11)
>  
>  #define BTRFS_INODE_ROOT_ITEM_INIT	(1 << 31)
> +#define BTRFS_INODE_FLAG_MASK		(((1 << 12) - 1) |\
> +					 BTRFS_INODE_ROOT_ITEM_INIT)
>  
>  struct btrfs_map_token {
>  	const struct extent_buffer *eb;
> diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
> index c08609627720..4b178ef1a9e7 100644
> --- a/fs/btrfs/tree-checker.c
> +++ b/fs/btrfs/tree-checker.c
> @@ -682,6 +682,102 @@ static int check_dev_item(struct btrfs_fs_info *fs_info,
>  	return -EUCLEAN;
>  }
>  
> +/* Inode item error output has the same format as dir_item_err() */
> +#define inode_item_err(fs_info, eb, slot, fmt, ...)	\
> +	dir_item_err(fs_info, eb, slot, fmt, __VA_ARGS__)
> +
> +static int check_inode_item(struct btrfs_fs_info *fs_info,
> +			    struct extent_buffer *leaf,
> +			    struct btrfs_key *key, int slot)
> +{
> +	struct btrfs_inode_item *iitem;
> +	u64 super_gen = btrfs_super_generation(fs_info->super_copy);
> +	u32 valid_mask = (S_IFMT | S_ISUID | S_ISGID | S_ISVTX | 0777);
> +	u32 mode;
> +
> +	if ((key->objectid < BTRFS_FIRST_FREE_OBJECTID ||
> +	     key->objectid > BTRFS_LAST_FREE_OBJECTID) &&
> +	     key->objectid != BTRFS_ROOT_TREE_DIR_OBJECTID &&
> +	     key->objectid != BTRFS_FREE_INO_OBJECTID) {
> +		generic_err(fs_info, leaf, slot,
> +	"invalid key objectid: has %llu expect %llu or [%llu, %llu] or %llu",
> +			    key->objectid, BTRFS_ROOT_TREE_DIR_OBJECTID,
> +			    BTRFS_FIRST_FREE_OBJECTID,
> +			    BTRFS_LAST_FREE_OBJECTID,
> +			    BTRFS_FREE_INO_OBJECTID);
> +		goto error;
> +	}
> +	if (key->offset != 0) {
> +		inode_item_err(fs_info, leaf, slot,
> +			"invalid key offset: has %llu expect 0",
> +			key->offset);
> +		goto error;
> +	}
> +	iitem = btrfs_item_ptr(leaf, slot, struct btrfs_inode_item);
> +
> +	/* Here we use super block generation + 1 to handle log tree */
> +	if (btrfs_inode_generation(leaf, iitem) > super_gen + 1) {
> +		inode_item_err(fs_info, leaf, slot,
> +			"invalid inode generation: has %llu expect (0, %llu]",
> +			       btrfs_inode_generation(leaf, iitem),
> +			       super_gen + 1);
> +		goto error;
> +	}
> +	/* Note for ROOT_TREE_DIR_ITEM, mkfs could make its transid as 0 */
> +	if (btrfs_inode_transid(leaf, iitem) > super_gen + 1) {
> +		inode_item_err(fs_info, leaf, slot,
> +			"invalid inode generation: has %llu expect [0, %llu]",
> +			       btrfs_inode_transid(leaf, iitem),
> +			       super_gen + 1);
> +		goto error;
> +	}
> +
> +	/*
> +	 * For size and nbytes it's better not to be too strict, as for dir
> +	 * item its size/nbytes can easily get wrong, but doesn't affect
> +	 * any thing of the fs. So here we skip the check.
> +	 */
> +
> +	mode = btrfs_inode_mode(leaf, iitem);
> +	if (mode & ~valid_mask) {
> +		inode_item_err(fs_info, leaf, slot,
> +			       "unknown mode bit detected: 0x%x",
> +			       mode & ~valid_mask);
> +		goto error;
> +	}
> +
> +	/*
> +	 * S_IFMT is not bit mapped so we can't completely rely is_power_of_2(),
> +	 * but is_power_of_2() can save us from checking FIFO/CHR/DIR/REG.
> +	 * Only needs to check BLK, LNK and SOCKS
> +	 */
> +	if (!is_power_of_2(mode & S_IFMT)) {
> +		if (!S_ISLNK(mode) && ! S_ISBLK(mode) && !S_ISSOCK(mode)) {
> +			inode_item_err(fs_info, leaf, slot,
> +			"invalid mode: has 0%o expect valid S_IF* bit(s)",
> +				       mode & S_IFMT);
> +			goto error;
> +		}
> +	}
> +	if (S_ISDIR(mode) && btrfs_inode_nlink(leaf, iitem) > 1) {
> +		inode_item_err(fs_info, leaf, slot,
> +			       "invalid nlink: has %u expect no more than 1 for dir",
> +			btrfs_inode_nlink(leaf, iitem));
> +		goto error;
> +	}
> +	if (btrfs_inode_flags(leaf, iitem) & ~BTRFS_INODE_FLAG_MASK) {
> +		inode_item_err(fs_info, leaf, slot,
> +			       "unknown flags detected: 0x%llx",
> +			       btrfs_inode_flags(leaf, iitem) &
> +			       ~BTRFS_INODE_FLAG_MASK);
> +		goto error;
> +	}
> +	return 0;
> +
> +error:
> +	return -EUCLEAN;
> +}
> +
>  /*
>   * Common point to switch the item-specific validation.
>   */
> @@ -715,6 +811,9 @@ static int check_leaf_item(struct btrfs_fs_info *fs_info,
>  	case BTRFS_DEV_ITEM_KEY:
>  		ret = check_dev_item(fs_info, leaf, key, slot);
>  		break;
> +	case BTRFS_INODE_ITEM_KEY:
> +		ret = check_inode_item(fs_info, leaf, key, slot);
> +		break;
>  	}
>  	return ret;
>  }
>