From: Al Viro <viro@zeniv.linux.org.uk>
To: Alexander Lochmann <alexander.lochmann@tu-dortmund.de>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Jan Kara <jack@suse.cz>,
Horst Schirmeier <horst.schirmeier@tu-dortmund.de>
Subject: Re: [PATCH] Fix sync. in blkdev_write_iter() acessing i_flags
Date: Sat, 8 Dec 2018 00:49:44 +0000 [thread overview]
Message-ID: <20181208004944.GA2217@ZenIV.linux.org.uk> (raw)
In-Reply-To: <5c86e85f-0ad4-935a-3021-7046551f361f@tu-dortmund.de>
On Fri, Dec 07, 2018 at 08:49:16PM +0100, Alexander Lochmann wrote:
> > _What_ SUID bit? We are talking about a write to block device, for fsck sake...
> >
> That's the way I understood Jan's explanation:
> "
> Thinking more about this I'm not sure if this is actually the right
> solution. Because for example the write(2) can set S_NOSEC flag wrongly
> when it would race with chmod adding SUID bit. So probably we rather need
> to acquire i_rwsem in blkdev_write_iter() if file does not have S_NOSEC set
> (we don't want to acquire it unconditionally as that would heavily impact
> scalability of block device writes).
IDGI. We are talking about a block device here. What business could
file_remove_privs() have doing _anything_ to it? should_remove_suid() returns
to return 0 for those; what case do you have in mind? Somebody setting
security.capabilities on a block device inode?
IMO the bug here is file_remove_privs() not buggering off immediately
after having observed that we are dealing with a block device. It really
has nothing useful to do.
next prev parent reply other threads:[~2018-12-08 0:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-07 16:10 [PATCH] Fix sync. in blkdev_write_iter() acessing i_flags Alexander Lochmann
2018-12-07 17:58 ` Al Viro
2018-12-07 19:49 ` Alexander Lochmann
2018-12-08 0:49 ` Al Viro [this message]
2018-12-10 9:47 ` Jan Kara
2018-12-14 10:55 ` [PATCH] Abort file_remove_privs() for non-reg. files Alexander Lochmann
2018-12-17 8:28 ` Jan Kara
2019-01-11 15:42 ` Alexander Lochmann
2019-03-08 15:10 ` Alexander Lochmann
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