Re: segfault in ftpd

From: Mikko Tyolajarvi (mikko@dynas.se)
Date: 04/24/02


Date: Tue, 23 Apr 2002 19:53:53 -0700 (PDT)
From: Mikko Tyolajarvi <mikko@dynas.se>
To: blaz@si.FreeBSD.org

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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