Re: [Linux-ima-devel] [PATCH v4 2/5] ima: use fs method to read integrity data [updated]

[Jan K. <ja...@su...>]

On Tue 01-08-17 16:24:30, Mimi Zohar wrote:
> From: Christoph Hellwig <hc...@ls...>
> 
> Add a new ->integrity_read file operation to read data for integrity
> hash collection.  This is defined to be equivalent to ->read_iter,
> except that it will be called with the i_rwsem held exclusively.
> 
> Signed-off-by: Christoph Hellwig <hc...@ls...>
> Cc: Matthew Garrett <mat...@ne...>
> Cc: Jan Kara <ja...@su...>
> Cc: "Theodore Ts'o" <ty...@mi...>
> Cc: Andreas Dilger <adi...@di...>
> Cc: Jaegeuk Kim <ja...@ke...>
> Cc: Chao Yu <yu...@hu...>
> Cc: Steven Whitehouse <swh...@re...>
> Cc: Bob Peterson <rpe...@re...>
> Cc: David Woodhouse <dw...@in...>
> Cc: Dave Kleikamp <sh...@ke...>
> Cc: Ryusuke Konishi <kon...@la...>
> Cc: Mark Fasheh <mf...@ve...>
> Cc: Joel Becker <jl...@ev...>
> Cc: Richard Weinberger <ri...@no...>
> Cc: "Darrick J. Wong" <dar...@or...>
> Cc: Hugh Dickins <hu...@go...>
> Cc: Chris Mason <cl...@fb...>
> Signed-off-by: Mimi Zohar <zo...@li...>

...

> +static ssize_t ext4_file_integrity_read_iter(struct kiocb *iocb,
> +					     struct iov_iter *to)
> +{
> +	struct inode *inode = file_inode(iocb->ki_filp);
> +	int o_direct = iocb->ki_flags & IOCB_DIRECT;
> +
> +	lockdep_assert_held(&inode->i_rwsem);
> +	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
> +		return -EIO;
> +
> +	if (!iov_iter_count(to))
> +		return 0; /* skip atime */
> +
> +#ifdef CONFIG_FS_DAX
> +	if (IS_DAX(inode))
> +		return dax_iomap_rw(iocb, to, &ext4_iomap_ops);
> +#endif
> +	if (o_direct)
> +		return -EINVAL;
> +	return generic_file_read_iter(iocb, to);
> +}

I have noticed this o_direct check - why is it only in ext4 and shouldn't
rather higher layers make sure IOCB_DIRECT iocbs cannot reach
.integrity_read() methods?

								Honza
-- 
Jan Kara <ja...@su...>
SUSE Labs, CR