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Date: Tue, 25 Apr 2006 15:00:13 -0500
From: "Serge E. Hallyn" <serue@us.ibm.com>
To: Chris Boot <bootc@bootc.net>
Cc: Axelle Apvrille <axelle_apvrille@yahoo.fr>, Nix <nix@esperi.org.uk>,
       Arjan van de Ven <arjan@infradead.org>, drepper@gmail.com,
       linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org,
       disec-devel@lists.sourceforge.net
Subject: Re: [ANNOUNCE] Release Digsig 1.5: kernel module for run-timeauthentication of binaries
Message-ID: <20060425200013.GA7228@sergelap.austin.ibm.com>
References: <20060425161139.87285.qmail@web26109.mail.ukl.yahoo.com> <9C02B13C-8615-440B-A08C-AC463CC2E0AE@bootc.net>
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Quoting Chris Boot (bootc@bootc.net):
> On 25 Apr 2006, at 17:11, Axelle Apvrille wrote:
> 
> >- finally, note you also have choice not to sign this
> >elf loader of yours. If it isn't signed, it won't ever
> >run ;-)
> 
> Wouldn't you need to sign, say, /lib/ld-linux.so?  In that case, you  
> can simply get it to load an execute almost anything that's ELF, even  

It uses dlopen, which does mmap(PROT_EXEC), at which point digsig will
check for a signature.

If you rewrite it to not use mmap(PROT_EXEC), then the signature will
not match.  If you resign it, then you presumably know what you're
doing.

I don't see the problem in this case.

> on filesystems marked noexec, if I'm not mistaken...