linux-kernel - Re: [WTF] ... is going on with current->fs->{root,mnt} accesses in pohmelfs

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: <20100210133007.GA17744@ioremap.net>
Date:	Wed, 10 Feb 2010 16:30:07 +0300
From:	Evgeniy Polyakov <zbr@...emap.net>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [WTF] ... is going on with current->fs->{root,mnt} accesses in pohmelfs

On Wed, Feb 10, 2010 at 11:59:39AM +0000, Al Viro (viro@...IV.linux.org.uk) wrote:
> > Let me guess... Mmmm, it was in the yesterday newspaper, I remember.
> > Maybe when we chroot somewhere. I meant not mounted fs root, but
> > thread's root.
> 
> Why would a filesystem give a damn about the chroot of syscall originator
> in the first place?

That's the point - it is not needed.

> > > Why not use the dentries you've been given by VFS?
> > 
> > At writeback we do not have parents, so must find a path somehow.
> 
> Most of the places do have those just fine and unlike the writeback,
> rename et.al. really care which pathname is being dealt with...

POHMELFS uses writeback cache also for metadata, so effectively most of
such operations are also postponed. Later I turned that off though.

> BTW, what prevents writeback vs. rename races?

There are proper locks for such operations.

-- 
	Evgeniy Polyakov
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/