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Commit 29171e82 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Greg Kroah-Hartman
Browse files

ext4: don't allow any modifications to an immutable file 



commit 2e53840362771c73eb0a5ff71611507e64e8eecd upstream.

Don't allow any modifications to a file that's marked immutable, which
means that we have to flush all the writable pages to make the readonly
and we have to check the setattr/setflags parameters more closely.

Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4a5cc64d

fs/ext4/ioctl.c

+45 −1
Original line number Diff line number Diff line
@@ -268,6 +268,29 @@ static int uuid_is_zero(__u8 u[16]) 
}

#endif



/*

 * If immutable is set and we are not clearing it, we're not allowed to change

 * anything else in the inode.  Don't error out if we're only trying to set

 * immutable on an immutable file.

 */

static int ext4_ioctl_check_immutable(struct inode *inode, __u32 new_projid,

				      unsigned int flags)

{

	struct ext4_inode_info *ei = EXT4_I(inode);

	unsigned int oldflags = ei->i_flags;



	if (!(oldflags & EXT4_IMMUTABLE_FL) || !(flags & EXT4_IMMUTABLE_FL))

		return 0;



	if ((oldflags & ~EXT4_IMMUTABLE_FL) != (flags & ~EXT4_IMMUTABLE_FL))

		return -EPERM;

	if (ext4_has_feature_project(inode->i_sb) &&

	    __kprojid_val(ei->i_projid) != new_projid)

		return -EPERM;



	return 0;

}



static int ext4_ioctl_setflags(struct inode *inode,

			       unsigned int flags)

{
@@ -321,6 +344,20 @@ static int ext4_ioctl_setflags(struct inode *inode, 
			goto flags_out;

	}



	/*

	 * Wait for all pending directio and then flush all the dirty pages

	 * for this file.  The flush marks all the pages readonly, so any

	 * subsequent attempt to write to the file (particularly mmap pages)

	 * will come through the filesystem and fail.

	 */

	if (S_ISREG(inode->i_mode) && !IS_IMMUTABLE(inode) &&

	    (flags & EXT4_IMMUTABLE_FL)) {

		inode_dio_wait(inode);

		err = filemap_write_and_wait(inode->i_mapping);

		if (err)

			goto flags_out;

	}



	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);

	if (IS_ERR(handle)) {

		err = PTR_ERR(handle);
@@ -750,6 +787,10 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 
			return err;



		inode_lock(inode);

		err = ext4_ioctl_check_immutable(inode,

				from_kprojid(&init_user_ns, ei->i_projid),

				flags);

		if (!err)

			err = ext4_ioctl_setflags(inode, flags);

		inode_unlock(inode);

		mnt_drop_write_file(filp);
@@ -1120,6 +1161,9 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 
			goto out;

		flags = (ei->i_flags & ~EXT4_FL_XFLAG_VISIBLE) |

			 (flags & EXT4_FL_XFLAG_VISIBLE);

		err = ext4_ioctl_check_immutable(inode, fa.fsx_projid, flags);

		if (err)

			goto out;

		err = ext4_ioctl_setflags(inode, flags);

		if (err)

			goto out;