linux-kernel - Re: [PATCH 2/6] ext4: Check for atomic writes support in write iter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b6f456bb-9998-4789-830d-45767dbbfdea@oracle.com>
Date: Fri, 25 Oct 2024 10:44:56 +0100
From: John Garry <john.g.garry@...cle.com>
To: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>, linux-ext4@...r.kernel.org
Cc: Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>,
        "Darrick J . Wong" <djwong@...nel.org>,
        Christoph Hellwig
 <hch@...radead.org>,
        Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
        Dave Chinner <david@...morbit.com>, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 2/6] ext4: Check for atomic writes support in write iter

On 25/10/2024 04:45, Ritesh Harjani (IBM) wrote:
> Let's validate using generic_atomic_write_valid() in
> ext4_file_write_iter() if the write request has IOCB_ATOMIC set.
> 
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@...il.com>
> ---
>   fs/ext4/file.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index f14aed14b9cf..b06c5d34bbd2 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -692,6 +692,20 @@ ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
>   	if (IS_DAX(inode))
>   		return ext4_dax_write_iter(iocb, from);
>   #endif
> +
> +	if (iocb->ki_flags & IOCB_ATOMIC) {
> +		size_t len = iov_iter_count(from);
> +		int ret;
> +
> +		if (!IS_ALIGNED(len, EXT4_SB(inode->i_sb)->fs_awu_min) ||
> +			len > EXT4_SB(inode->i_sb)->fs_awu_max)
> +			return -EINVAL;

this looks ok, but the IS_ALIGNED() check looks odd. I am not sure why 
you don't just check that fs_awu_max >= len >= fs_awu_min

> +
> +		ret = generic_atomic_write_valid(iocb, from);
> +		if (ret)
> +			return ret;
> +	}
> +
>   	if (iocb->ki_flags & IOCB_DIRECT)
>   		return ext4_dio_write_iter(iocb, from);
>   	else