Date: Mon, 18 Nov 1996 08:30:43 +0100 From: Poul-Henning Kamp <phk@critter.tfs.com> To: Michael Smith <msmith@atrad.adelaide.edu.au> Cc: imp@village.org (Warner Losh), newton@communica.com.au, batie@agora.rdrop.com, adam@homeport.org, pgiffuni@fps.biblos.unal.edu.co, freebsd-security@FreeBSD.org Subject: Re: BoS: Exploit for sendmail smtpd bug (ver. 8.7-8.8.2). Message-ID: <9172.848302243@critter.tfs.com> In-Reply-To: Your message of "Mon, 18 Nov 1996 14:05:04 %2B1030." <199611180335.OAA17231@genesis.atrad.adelaide.edu.au>
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In message <199611180335.OAA17231@genesis.atrad.adelaide.edu.au>, Michael Smith writes: >Warner Losh stands accused of saying: >> >> I don't buy this. You need to be able to create a mailbox of an >> arbitrary user, and then write to that mailbox with that user's uid, >> or to a shell of that user's uid. To do otherwise would introduce >> other security problems, some of which have been beat to death in the >> freebsd lists. >> >> What am I missing? > >mail.local. > >Mark's sense of warmth is perhaps slightly over-smug, but his point is >valid. In fact, if it were possible to be non-root and bind to port 25, >then sendmail could be run non-root in daemon mode and not be called from >cron (which Mark omitted to mention). What we REALLY need, is a way for root, to hand out certain priviledges. Imagine this: sysctl -w net.inet.tcp.uidforport.25=`id -ur smtp` sysctl -w net.inet.tcp.uidforport.20=`id -ur ftp` sysctl -w net.inet.tcp.uidforport.21=`id -ur ftp` sysctl -w net.inet.tcp.uidforport.119=`id -ur nntp` This means that users with UID smtp can bind to socket 25 (aka smtp), and so on. Now sendmail NEVER needs to be root. How's that for security ? -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. Future will arrive by its own means, progress not so.
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