Re: [ANNOUNCE] Release Digsig 1.3.1: kernel module for run-time authentication of binaries

Chris Wright
2004-09-10T21:30:36Z

* Serge E. Hallyn (serue@us.ibm.com) wrote:
> > Thing is, x86 makes no distinction btween r/x so, have you tried mmaping
> > with read, then executing (I haven't)?
>
> Yup, clearly that will work on x86. And so obviously DigSig is not
> a solution to format and buffer overflows :) Nor, unfortunately, a

heh

> solution to code which for whatever reason exploited this behavior.

That's what I was getting at. Beats me what's out there that does this,
but I expect some stuff does, and it wouldn't get the same assurance.

> > This has nothing to do with file permissions aside of read. All you need
> > is read permission, then you can mmap(PROT_EXEC) which will kick off the
> > check, and do deny_write_access. It's a freeform way to lock writers
> > out of any readable file in the system.
>
> No, not "any readable file," because DigSig will not lock non-ELF files.

Ahh, this is the part I had missed.

thanks,
-chris
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