Messages in this thread | | | Date | Thu, 1 Oct 2015 21:41:21 +0200 | From | Borislav Petkov <> | Subject | Re: [RFC][PATCH] x86/mm: warn on W+x mappings |
| |
On Thu, Oct 01, 2015 at 12:24:25PM -0700, Kees Cook wrote: > On Thu, Oct 1, 2015 at 9:28 AM, Stephen Smalley <sds@tycho.nsa.gov> wrote: > > Warn on any residual W+x mappings if X86_PTDUMP is enabled. > > > > Sample dmesg output: > > Checking for W+x mappings > > 0xffffffff81755000-0xffffffff81800000 684K RW GLB x pte > > Found W+x mappings. Please fix. > > > > Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> > > --- > > Not sure if this is the best place to put this check. > > It must occur after free_init_pages() or it won't catch the > > W+x case for the gap between __ex_table and rodata. > > Yeah. Hmm. I want this test for sure, but I'd like to be able to do > with without needing PTDUMP, since that puts a very sensitive file in > debugfs. I wonder if we can reuse the same code, but only expose the > page tables to userspace with PTDUMP?
So make it a debugging option like CONFIG_EFI_PGT_DUMP and let it dump the pagetable in dmesg during boot, at the exact point you want it to. Then one can grep dmesg for W+x bits or whatever else...
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply.
| |