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new ELF marking
- From: "Kees Cook via binutils" <binutils at sourceware dot org>
- To: LKML <linux-kernel at vger dot kernel dot org>, binutils at sourceware dot org
- Date: Wed, 9 Aug 2017 10:07:54 -0700
- Subject: new ELF marking
- Authentication-results: sourceware.org; auth=none
- Reply-to: Kees Cook <keescook at google dot com>
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.