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From: Willy Tarreau <w@1wt.eu>
To: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: "David S. Miller" <davem@davemloft.net>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Eric Dumazet <edumazet@google.com>,
	socketpair@gmail.com
Subject: Re: [PATCH] unix: properly account for FDs passed over unix sockets
Date: Wed, 30 Dec 2015 12:23:17 +0100	[thread overview]
Message-ID: <20151230112317.GC14049@1wt.eu> (raw)
In-Reply-To: <56839CC2.9080000@stressinduktion.org>

On Wed, Dec 30, 2015 at 09:58:42AM +0100, Hannes Frederic Sowa wrote:
> The MSG_PEEK code should not be harmful and the patch is good as is. I 
> first understood from the published private thread, that it is possible 
> for a program to exceed the rlimit of fds. But the DoS is only by 
> keeping the fds in flight and not attaching them to any program.

Exactly. The real issue is when these FDs become very expensive such as
pipes full of data.

> __alloc_fd, called on the receiver side, does check for the rlimit 
> maximum anyway, so I don't see a loophole anymore:
> 
> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>

Thanks!

> Another idea would be to add the amount of memory used to manage the fds 
> to sock_rmem/wmem but I don't see any advantages or disadvantages.

Compared to the impact of the pending data in pipes themselves in flight,
this would remain fairly minimal.

Thanks,
Willy

  reply	other threads:[~2015-12-30 11:23 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-28 14:14 [PATCH] unix: properly account for FDs passed over unix sockets Willy Tarreau
2015-12-29 14:37 ` Hannes Frederic Sowa
2015-12-29 14:48 ` Hannes Frederic Sowa
2015-12-29 20:35   ` Willy Tarreau
2015-12-30  8:58     ` Hannes Frederic Sowa
2015-12-30 11:23       ` Willy Tarreau [this message]
2015-12-30 13:14         ` One Thousand Gnomes
2015-12-31  6:08         ` Tetsuo Handa
2015-12-31  7:12           ` Willy Tarreau
2015-12-31 10:27             ` One Thousand Gnomes
2016-01-04 21:44 ` David Miller

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