Date: Tue, 16 Nov 1999 13:03:39 -0500 From: Greg Lehey <grog@mojave.sitaranetworks.com> To: Graham Wheeler <gram@cequrux.com>, hackers@FreeBSD.ORG Subject: Re: Missing core dumps Message-ID: <19991116130339.17641@mojave.sitaranetworks.com> In-Reply-To: <9911161453040F.23105@cequrux.com>; from Graham Wheeler on Tue, Nov 16, 1999 at 02:45:26PM %2B0200 References: <9911161453040F.23105@cequrux.com>
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On Tuesday, 16 November 1999 at 14:45:26 +0200, Graham Wheeler wrote: > Howdy all > > I have a program that occasionally catches a SEGV signal, but it doesn't dump > core. And I really could use that core file, as I can't replicate the problem > under controlled conditions. > > The program is invoked from inetd. It is owned by user nobody and has group > mail. When it starts up, it calls setuid and setgid to set the user and group > to be nobody and mail respectively. It then chroots to a directory which is > owned by bin and has group mail. This directory has owner and group read, > write and execute permissions on. The program can create and destroy temporary > files in this directory without any problem. > > It doesn't catch SEGV signals in its own handler, and it has no obvious file > size limits. > > From my reading of Stevens APITUE, there are no reasons why the core file > shouldn't be created. Am I missing something? (This is on 2.2.7 and 2.2.8 > systems, although I suspect the behaviour will be unchanged under 3.x) For security reasons, you normally can't get a core dump of a setuid program. You could use it to break security. To change this behaviour, set the sysctl sugid.coredump: # sysctl -w sugid.coredump=1 BTW, this knob isn't mentioned in the man page. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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