Messages in this thread | | | Date | Fri, 20 Oct 2006 13:54:14 +0200 | From | Marcus Meissner <> | Subject | Re: [PATCH] binfmt_elf: randomize PIE binaries |
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On Thu, Oct 19, 2006 at 04:23:54PM -0400, Dave Jones wrote: > On Thu, Oct 19, 2006 at 04:35:47PM +0200, Marcus Meissner wrote: > > > --- linux-2.6.18/fs/binfmt_elf.c.xx 2006-10-19 11:21:49.000000000 +0200 > > +++ linux-2.6.18/fs/binfmt_elf.c 2006-10-19 11:24:58.000000000 +0200 > > @@ -856,7 +856,12 @@ static int load_elf_binary(struct linux_ > > * default mmap base, as well as whatever program they > > * might try to exec. This is because the brk will > > * follow the loader, and is not movable. */ > > - load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr); > > + if (current->flags & PF_RANDOMIZE) > > + load_bias = randomize_range(0, ELF_ET_DYN_BASE, > > + vaddr); > > + else > > + load_bias = ELF_ET_DYN_BASE - vaddr; > > + load_bias = ELF_PAGESTART(load_bias); > > } > > > > error = elf_map(bprm->file, load_bias + vaddr, elf_ppnt, > > > vaddr seems odd to be using as the len for randomize_range doesn't it ? > Should that be randomize_range(0, ELF_ET_DYN_BASE, ELF_ET_DYN_BASE - vaddr); > > maybe ?
> Also, when we get to the elf_map(), we add vaddr back again, but in the > randomize_range case, we never subtracted it. hmm?
Yes, the code was not really doing what I actually intended. (It was working, but the range always started at vaddr).
I am using randomize_range (PAGE_SIZE, ELF_ET_DYN_BASE,0) (- vaddr) now after further comments from Arjan.
Any other good ideas for a range to do the randomization in are welcome.
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