linux-kernel - Re: [PATCH v3] vfs: new O

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]

Date:	Thu, 03 Dec 2009 06:46:27 +0100
From:	Miklos Szeredi <miklos@...redi.hu>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	miklos@...redi.hu, akpm@...ux-foundation.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] vfs: new O_NODE open flag

On Wed, 2 Dec 2009, Alan Cox wrote:
> > You're still missing the point.  O_NODE is like a hard link, except
> > the reference doesn't come from the filesystem but from a file
> > descriptor.  From udev's perspective there's no difference.
> 
> I don't think I am missing the point here. You have a reference to an
> object in the fs but you don't have a reference to the driver underneath
> s the driver can change on you *while* you have the O_NODE open and fd
> live. That cannot happen with a hard link and open.
> 
> It isn't the same thing as far as I can see. You don't have the barrier
> between the operations that occurs in the real open/close case because
> they lock the driver.

The file descriptor opened with O_NODE allows exaclactly the same
operations that a hard link to the device would, nothing more.  It's
just a link to the *node*, except it doesn't increment the link count,
the driver is irrelevant.

Miklos
--
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/