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Re: new ELF marking
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Kees Cook <keescook at google dot com>
- Cc: LKML <linux-kernel at vger dot kernel dot org>, Binutils <binutils at sourceware dot org>
- Date: Wed, 9 Aug 2017 10:16:57 -0700
- Subject: Re: new ELF marking
- Authentication-results: sourceware.org; auth=none
- References: <CAGXu5jL2iY8=VhWyqhhUqxAs1akywodrWezU77rnrq-Ksbzwow@mail.gmail.com>
On Wed, Aug 9, 2017 at 10:07 AM, Kees Cook via binutils
> I'd like to be able to mark an ELF binary in such a way that Linux's
> binfmt_elf.c will collapse a PIE text area into the mmap region
> (currently they are separately randomized in memory). This is desired
> by AddressSanitizer to avoid having an ASan-built binary have its text
> area moving into an unexpected location (ASLR is still desired, but
> doesn't need to have a PIE/mmap split).
> I see a few ways:
> - Add parsing for NOTE program headers and add a new NOTE type
> (NT_GNU_EXEC_FLAGS), though notes tend to be strings...
> - Add a new Program Header (GNU_EXEC_FLAGS), which is similar to how
> GNU_STACK and GNU_RELRO were handled. This could sort of be like NOTE
> except just lots of bit flags.
> - Use a filesystem xattr. This is fragile, in the case of copying
> binaries between systems or filesystems.
Why don't you use NT_GNU_PROPERTY_TYPE_0?