netdev - Re: [tipc] dest_name_check() is racy (potential security hole)

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Date:	Mon, 7 Apr 2014 10:08:52 +0200
From:	Erik Hugne <erik.hugne@...csson.com>
To:	Al Viro <viro@...IV.linux.org.uk>
CC:	<netdev@...r.kernel.org>, Jon Maloy <jon.maloy@...csson.com>
Subject: Re: [tipc] dest_name_check() is racy (potential security hole)

On Sun, Apr 06, 2014 at 05:39:34AM +0100, Al Viro wrote:
> According to the comment in front of it, it "prevents restricted configuration
> commands from being issued by unauthorized users".  Makes sense, right?
> Except that it obviously doesn't provide any security whatsoever, because
> the value we'd read from the iovec is immediately discarded and later
> we reread it again.
> 
> There is nothing to stop the caller from spawning a threar that would flip
> the bits in question back and forth, while the parent keeps calling sendmsg().
> Sooner or later we will have dest_name_check() pick the harmless value,
> with subsequent memcpy_fromiovecend() picking the modified one.

Ack, but as of commit 5902385a2440a55f005b266c93e0bb9398e5a62b ("tipc: obsolete the
remote management feature) this is no longer an issue. We missed to remove the
TIPC_CFG_SRV/CAP_NET_ADMIN check in that commit aswell.

//W
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