linux-kernel - Re: [PATCH 1/4] coredump: add an interface to control the core dump routine

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:	Fri, 30 Mar 2007 09:10:28 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	"Kawai, Hidehiro" <hidehiro.kawai.ez@...achi.com>
Cc:	David Howells <dhowells@...hat.com>, Pavel Machek <pavel@....cz>,
	kernel list <linux-kernel@...r.kernel.org>,
	Robin Holt <holt@....com>, Alan Cox <alan@...rguk.ukuu.org.uk>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	sugita <yumiko.sugita.yf@...achi.com>,
	Satoshi OSHIMA <soshima@...hat.com>,
	Hideo AOKI <haoki@...hat.com>
Subject: Re: [PATCH 1/4] coredump: add an interface to control the core dump
 routine

On Fri, 30 Mar 2007 19:29:23 +0900 "Kawai, Hidehiro" <hidehiro.kawai.ez@...achi.com> wrote:

> > core_pattern:
> >   ...
> > . If the first character of the pattern is a '|', the kernel will treat
> >   the rest of the pattern as a command to run.  The core dump will be
> >   written to the standard input of that program instead of to a file.
> 
> I think dumping core over a pipe is almost good.  Filtering and writing
> out a core by a separete userspace program can be reliable because it is
> independent of the failed user process.  But I have one concern; data
> transfer over a pipe is slow.  It took 7 seconds to transfer 2GB
> anonymous shared memory (detailed at the last of this mail).
> 
> In the case of dumping hundreds processes which share giga bytes memory,
> it will take a few minutes even if the huge shared memory is not written
> to a disk.  If a user wants to restart the failed application as soon
> as possible to keep downtime to a minimum, this extra transfer time will
> be a barrier.  So I think in-kernel filtering is still needed.

Yes, I agree - I don't think we presently have a way of avoiding having
to send all of that uninteresting data down the pipe.

One may, however, be able to play tricks with /proc/<pid>/mem from within
the corefile-generating program: select the vmas which are to be dumped,
read only those ones.  I don't know how practical that would be.
-
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/