Messages in this thread | | | Subject | Re: [ANNOUNCE] Release Digsig 1.5: kernel module for run-timeauthentication of binaries | From | Nix <> | Date | Mon, 24 Apr 2006 21:32:39 +0100 |
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On 24 Apr 2006, Arjan van de Ven announced authoritatively: > On Mon, 2006-04-24 at 12:27 -0400, Makan Pourzandi (QB/EMC) wrote: >> Hi Arjan, >> >> I hope I correctly understood your question, DigSig uses LSM hooks to >> check the digital signature before loading it, then as long as your elf >> loader uses kernel system calls, it's covered by DigSig. > > ok I have to admit that this answer worries me. > > how can it be covered? How do you distinguish an elf loader application > (which just uses open + mmap after all) with... say a grep-calling perl > script?
It checks mmap and mprotect with PROT_EXEC, and execve().
> As long as you allow apps to mmap (or even just read() a file into > memory).... they can start acting like an elf loader if they chose to do > so. And.. remember it's not the files WITH signature you're protecting > against (which you could check) but the ones WITHOUT. And there are many > of those; and you can't sign ALL files I think, not without going > through really great hoops anyway.
Why not? It's one command with bsign:
bsign -s -I -i / -e /proc
will sign every ELF shared object and executable on the system.
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