From: Amir Goldstein <amir73il@gmail.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: matthew.garrett@nebula.com, Chao Yu <yuchao0@huawei.com>,
Theodore Tso <tytso@mit.edu>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Josef Bacik <josef@toxicpanda.com>,
Christoph Hellwig <hch@infradead.org>, Chris Mason <clm@fb.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.com>,
David Sterba <dsterba@suse.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
jk@ozlabs.org, reiserfs-devel@vger.kernel.org,
linux-efi@vger.kernel.org, devel@lists.orangefs.org,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-f2fs-devel@lists.sourceforge.net,
linux-xfs <linux-xfs@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
linux-nilfs@vger.kernel.org, linux-mtd@lists.infradead.org,
ocfs2-devel@oss.oracle.com,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Ext4 <linux-ext4@vger.kernel.org>,
Linux Btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] vfs: don't allow most setxattr to immutable files
Date: Tue, 2 Jul 2019 13:45:32 +0300 [thread overview]
Message-ID: <CAOQ4uxizFXgSa4KzkwxmoPAvpiENg=y0=fsxEC1PkCX5J1ybag@mail.gmail.com> (raw)
In-Reply-To: <20190701154200.GK1404256@magnolia>
On Mon, Jul 1, 2019 at 7:31 PM Darrick J. Wong <darrick.wong@oracle.com> wrote:
>
> From: Darrick J. Wong <darrick.wong@oracle.com>
>
> The chattr manpage has this to say about immutable files:
>
> "A file with the 'i' attribute cannot be modified: it cannot be deleted
> or renamed, no link can be created to this file, most of the file's
> metadata can not be modified, and the file can not be opened in write
> mode."
>
> However, we don't actually check the immutable flag in the setattr code,
> which means that we can update inode flags and project ids and extent
> size hints on supposedly immutable files. Therefore, reject setflags
> and fssetxattr calls on an immutable file if the file is immutable and
> will remain that way.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> v2: use memcmp instead of open coding a bunch of checks
Thanks,
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> ---
> fs/inode.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/fs/inode.c b/fs/inode.c
> index cf07378e5731..31f694e405fe 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -2214,6 +2214,14 @@ int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags,
> !capable(CAP_LINUX_IMMUTABLE))
> return -EPERM;
>
> + /*
> + * We aren't allowed to change any other flags if the immutable flag is
> + * already set and is not being unset.
> + */
> + if ((oldflags & FS_IMMUTABLE_FL) && (flags & FS_IMMUTABLE_FL) &&
> + oldflags != flags)
> + return -EPERM;
> +
> /*
> * Now that we're done checking the new flags, flush all pending IO and
> * dirty mappings before setting S_IMMUTABLE on an inode via
> @@ -2284,6 +2292,15 @@ int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa,
> !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)))
> return -EINVAL;
>
> + /*
> + * We aren't allowed to change any fields if the immutable flag is
> + * already set and is not being unset.
> + */
> + if ((old_fa->fsx_xflags & FS_XFLAG_IMMUTABLE) &&
> + (fa->fsx_xflags & FS_XFLAG_IMMUTABLE) &&
> + memcmp(fa, old_fa, offsetof(struct fsxattr, fsx_pad)))
> + return -EPERM;
> +
> /* Extent size hints of zero turn off the flags. */
> if (fa->fsx_extsize == 0)
> fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE | FS_XFLAG_EXTSZINHERIT);
next prev parent reply other threads:[~2019-07-02 10:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-28 18:34 [PATCH v6 0/4] vfs: make immutable files actually immutable Darrick J. Wong
2019-06-28 18:34 ` [PATCH 1/4] mm/fs: don't allow writes to immutable files Darrick J. Wong
2019-06-28 18:34 ` [PATCH 2/4] vfs: flush and wait for io when setting the immutable flag via SETFLAGS Darrick J. Wong
2019-06-28 18:34 ` [PATCH 3/4] vfs: flush and wait for io when setting the immutable flag via FSSETXATTR Darrick J. Wong
2019-06-28 18:35 ` [PATCH 4/4] vfs: don't allow most setxattr to immutable files Darrick J. Wong
2019-06-29 7:04 ` Amir Goldstein
2019-07-01 15:42 ` [PATCH v2 " Darrick J. Wong
2019-07-02 10:45 ` Amir Goldstein [this message]
2019-07-01 17:20 ` [PATCH v6 0/4] vfs: make immutable files actually immutable Boaz Harrosh
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