Commit 814525f4 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
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ext4: calculate and verify inode checksums 



This patch introduces to ext4 the ability to calculate and verify
inode checksums.  This requires the use of a new ro compatibility flag
and some accompanying e2fsprogs patches to provide the relevant
features in tune2fs and e2fsck.  The inode generation changes have
been integrated into this patch.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent a9c47317

fs/ext4/ext4.h

+3 −0
Original line number Diff line number Diff line
@@ -915,6 +915,9 @@ struct ext4_inode_info { 
	 */

	tid_t i_sync_tid;

	tid_t i_datasync_tid;



	/* Precomputed uuid+inum+igen checksum for seeding inode checksums */

	__u32 i_csum_seed;

};



/*

fs/ext4/ialloc.c

+13 −0
Original line number Diff line number Diff line
@@ -850,6 +850,19 @@ got: 
	inode->i_generation = sbi->s_next_generation++;

	spin_unlock(&sbi->s_next_gen_lock);



	/* Precompute checksum seed for inode metadata */

	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,

			EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {

		__u32 csum;

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

		__le32 inum = cpu_to_le32(inode->i_ino);

		__le32 gen = cpu_to_le32(inode->i_generation);

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

				   sizeof(inum));

		ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,

					      sizeof(gen));

	}



	ext4_clear_state_flags(ei); /* Only relevant on 32-bit archs */

	ext4_set_inode_state(inode, EXT4_STATE_NEW);

fs/ext4/inode.c

+103 −8
Original line number Diff line number Diff line
@@ -47,6 +47,73 @@ 


#define MPAGE_DA_EXTENT_TAIL 0x01



static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,

			      struct ext4_inode_info *ei)

{

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

	__u16 csum_lo;

	__u16 csum_hi = 0;

	__u32 csum;



	csum_lo = raw->i_checksum_lo;

	raw->i_checksum_lo = 0;

	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&

	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {

		csum_hi = raw->i_checksum_hi;

		raw->i_checksum_hi = 0;

	}



	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw,

			   EXT4_INODE_SIZE(inode->i_sb));



	raw->i_checksum_lo = csum_lo;

	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&

	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))

		raw->i_checksum_hi = csum_hi;



	return csum;

}



static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,

				  struct ext4_inode_info *ei)

{

	__u32 provided, calculated;



	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=

	    cpu_to_le32(EXT4_OS_LINUX) ||

	    !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,

		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))

		return 1;



	provided = le16_to_cpu(raw->i_checksum_lo);

	calculated = ext4_inode_csum(inode, raw, ei);

	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&

	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))

		provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;

	else

		calculated &= 0xFFFF;



	return provided == calculated;

}



static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,

				struct ext4_inode_info *ei)

{

	__u32 csum;



	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=

	    cpu_to_le32(EXT4_OS_LINUX) ||

	    !EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,

		EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))

		return;



	csum = ext4_inode_csum(inode, raw, ei);

	raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);

	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&

	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))

		raw->i_checksum_hi = cpu_to_le16(csum >> 16);

}



static inline int ext4_begin_ordered_truncate(struct inode *inode,

					      loff_t new_size)

{
@@ -3644,6 +3711,39 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) 
	if (ret < 0)

		goto bad_inode;

	raw_inode = ext4_raw_inode(&iloc);



	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {

		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);

		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >

		    EXT4_INODE_SIZE(inode->i_sb)) {

			EXT4_ERROR_INODE(inode, "bad extra_isize (%u != %u)",

				EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize,

				EXT4_INODE_SIZE(inode->i_sb));

			ret = -EIO;

			goto bad_inode;

		}

	} else

		ei->i_extra_isize = 0;



	/* Precompute checksum seed for inode metadata */

	if (EXT4_HAS_RO_COMPAT_FEATURE(sb,

			EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {

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

		__u32 csum;

		__le32 inum = cpu_to_le32(inode->i_ino);

		__le32 gen = raw_inode->i_generation;

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

				   sizeof(inum));

		ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,

					      sizeof(gen));

	}



	if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {

		EXT4_ERROR_INODE(inode, "checksum invalid");

		ret = -EIO;

		goto bad_inode;

	}



	inode->i_mode = le16_to_cpu(raw_inode->i_mode);

	inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);

	inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
@@ -3721,12 +3821,6 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) 
	}



	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {

		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);

		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >

		    EXT4_INODE_SIZE(inode->i_sb)) {

			ret = -EIO;

			goto bad_inode;

		}

		if (ei->i_extra_isize == 0) {

			/* The extra space is currently unused. Use it. */

			ei->i_extra_isize = sizeof(struct ext4_inode) -
@@ -3738,8 +3832,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino) 
			if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))

				ext4_set_inode_state(inode, EXT4_STATE_XATTR);

		}

	} else

		ei->i_extra_isize = 0;

	}



	EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);

	EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
@@ -3963,6 +4056,8 @@ static int ext4_do_update_inode(handle_t *handle, 
		raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);

	}



	ext4_inode_csum_set(inode, raw_inode, ei);



	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");

	rc = ext4_handle_dirty_metadata(handle, NULL, bh);

	if (!err)

fs/ext4/ioctl.c

+7 −0
Original line number Diff line number Diff line
@@ -152,6 +152,13 @@ flags_out: 
		if (!inode_owner_or_capable(inode))

			return -EPERM;



		if (EXT4_HAS_RO_COMPAT_FEATURE(inode->i_sb,

				EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) {

			ext4_warning(sb, "Setting inode version is not "

				     "supported with metadata_csum enabled.");

			return -ENOTTY;

		}



		err = mnt_want_write_file(filp);

		if (err)

			return err;

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