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Date:      Tue, 23 Apr 2002 19:53:53 -0700 (PDT)
From:      Mikko Tyolajarvi <mikko@dynas.se>
To:        blaz@si.FreeBSD.org
Cc:        security@freebsd.org
Subject:   Re: segfault in ftpd
Message-ID:  <200204240253.g3O2rrM33014@mikko.rsa.com>
References:  <20020423225805.Q93786-100000@titanic.medinet.si>

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In local.freebsd.security you write:

>For some time now I see messages like this in the logs on our webserver:

>pid 36861 (ftpd), uid 29987: exited on signal 11

>This is with the stock ftpd on 4.5-RELEASE-p3 (users use it to upload their
>web pages to it). I compiled ftpd with -g and tried to set it up so that I get
>a coredump. I configured:

>	mkdir /var/coredumps
>	chmod 1777 /var/coredumps
>	sysctl kern.corefile=/var/coredumps/%U.%N.%P.core

>Now I can create a simple program that crashes and the core will be written to
>/var/coredumps. But ftpd simply does not want to create a coredump. As far as
>I can see, /etc/login.conf specifies coredumpsize=unlimited. Is there anything
>else I need to configure or tune to be able to catch a coredump?

Try:

   sysctl kern.sugid_coredump=1

If ftpd crashes after user login, then UID != EUID (which is what
makes it such a security problem in the first place -- how often do
you _really_ need to change user in the middle of an ftp session?
It should just switch uid and be done with it, IMHO).

  $.02,
  /Mikko
-- 
 Mikko Työläjärvi_______________________________________mikko@rsasecurity.com
 RSA Security

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