Commit cc8e94fd authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

ext4: Calculate and verify checksums of extended attribute blocks 



Calculate and verify the checksums of extended attribute blocks.  This
only applies to separate EA blocks that are pointed to by
inode->i_file_acl (i.e.  external EA blocks); the checksum lives in
the EA header.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent b0336e8d

fs/ext4/xattr.c

+77 −15
Original line number Diff line number Diff line
@@ -122,6 +122,58 @@ const struct xattr_handler *ext4_xattr_handlers[] = { 
	NULL

};



static __le32 ext4_xattr_block_csum(struct inode *inode,

				    sector_t block_nr,

				    struct ext4_xattr_header *hdr)

{

	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);

	struct ext4_inode_info *ei = EXT4_I(inode);

	__u32 csum, old;



	old = hdr->h_checksum;

	hdr->h_checksum = 0;

	if (le32_to_cpu(hdr->h_refcount) != 1) {

		block_nr = cpu_to_le64(block_nr);

		csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&block_nr,

				   sizeof(block_nr));

	} else

		csum = ei->i_csum_seed;

	csum = ext4_chksum(sbi, csum, (__u8 *)hdr,

			   EXT4_BLOCK_SIZE(inode->i_sb));

	hdr->h_checksum = old;

	return cpu_to_le32(csum);

}



static int ext4_xattr_block_csum_verify(struct inode *inode,

					sector_t block_nr,

					struct ext4_xattr_header *hdr)

{

	if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,

		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&

	    (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))

		return 0;

	return 1;

}



static void ext4_xattr_block_csum_set(struct inode *inode,

				      sector_t block_nr,

				      struct ext4_xattr_header *hdr)

{

	if (!EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,

		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))

		return;



	hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);

}



static inline int ext4_handle_dirty_xattr_block(handle_t *handle,

						struct inode *inode,

						struct buffer_head *bh)

{

	ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));

	return ext4_handle_dirty_metadata(handle, inode, bh);

}



static inline const struct xattr_handler *

ext4_xattr_handler(int name_index)

{
@@ -156,12 +208,22 @@ ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end) 
}



static inline int

ext4_xattr_check_block(struct buffer_head *bh)

ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)

{

	int error;



	if (buffer_verified(bh))

		return 0;



	if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||

	    BHDR(bh)->h_blocks != cpu_to_le32(1))

		return -EIO;

	return ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);

	if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))

		return -EIO;

	error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);

	if (!error)

		set_buffer_verified(bh);

	return error;

}



static inline int
@@ -224,7 +286,7 @@ ext4_xattr_block_get(struct inode *inode, int name_index, const char *name, 
		goto cleanup;

	ea_bdebug(bh, "b_count=%d, refcount=%d",

		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));

	if (ext4_xattr_check_block(bh)) {

	if (ext4_xattr_check_block(inode, bh)) {

bad_block:

		EXT4_ERROR_INODE(inode, "bad block %llu",

				 EXT4_I(inode)->i_file_acl);
@@ -369,7 +431,7 @@ ext4_xattr_block_list(struct dentry *dentry, char *buffer, size_t buffer_size) 
		goto cleanup;

	ea_bdebug(bh, "b_count=%d, refcount=%d",

		atomic_read(&(bh->b_count)), le32_to_cpu(BHDR(bh)->h_refcount));

	if (ext4_xattr_check_block(bh)) {

	if (ext4_xattr_check_block(inode, bh)) {

		EXT4_ERROR_INODE(inode, "bad block %llu",

				 EXT4_I(inode)->i_file_acl);

		error = -EIO;
@@ -492,7 +554,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode, 
		if (ce)

			mb_cache_entry_release(ce);

		unlock_buffer(bh);

		error = ext4_handle_dirty_metadata(handle, inode, bh);

		error = ext4_handle_dirty_xattr_block(handle, inode, bh);

		if (IS_SYNC(inode))

			ext4_handle_sync(handle);

		dquot_free_block(inode, 1);
@@ -662,7 +724,7 @@ ext4_xattr_block_find(struct inode *inode, struct ext4_xattr_info *i, 
		ea_bdebug(bs->bh, "b_count=%d, refcount=%d",

			atomic_read(&(bs->bh->b_count)),

			le32_to_cpu(BHDR(bs->bh)->h_refcount));

		if (ext4_xattr_check_block(bs->bh)) {

		if (ext4_xattr_check_block(inode, bs->bh)) {

			EXT4_ERROR_INODE(inode, "bad block %llu",

					 EXT4_I(inode)->i_file_acl);

			error = -EIO;
@@ -725,7 +787,7 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode, 
			if (error == -EIO)

				goto bad_block;

			if (!error)

				error = ext4_handle_dirty_metadata(handle,

				error = ext4_handle_dirty_xattr_block(handle,

								      inode,

								      bs->bh);

			if (error)
@@ -796,7 +858,7 @@ inserted: 
				ea_bdebug(new_bh, "reusing; refcount now=%d",

					le32_to_cpu(BHDR(new_bh)->h_refcount));

				unlock_buffer(new_bh);

				error = ext4_handle_dirty_metadata(handle,

				error = ext4_handle_dirty_xattr_block(handle,

								      inode,

								      new_bh);

				if (error)
@@ -855,7 +917,7 @@ getblk_failed: 
			set_buffer_uptodate(new_bh);

			unlock_buffer(new_bh);

			ext4_xattr_cache_insert(new_bh);

			error = ext4_handle_dirty_metadata(handle,

			error = ext4_handle_dirty_xattr_block(handle,

							      inode, new_bh);

			if (error)

				goto cleanup;
@@ -1193,7 +1255,7 @@ retry: 
		error = -EIO;

		if (!bh)

			goto cleanup;

		if (ext4_xattr_check_block(bh)) {

		if (ext4_xattr_check_block(inode, bh)) {

			EXT4_ERROR_INODE(inode, "bad block %llu",

					 EXT4_I(inode)->i_file_acl);

			error = -EIO;

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