Messages in this thread | | | Date | Wed, 07 Nov 2012 12:42:12 +0800 | From | Jeff Liu <> | Subject | Re: + binfmt_elfc-use-get_random_int-to-fix-entropy-depleting.patch added to -mm tree |
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On 11/07/2012 12:29 PM, Kees Cook wrote: > On Tue, Nov 6, 2012 at 8:21 PM, Jeff Liu <jeff.liu@oracle.com> wrote: >> Hi Andrew and Kees, >> >> Great thanks for both your comments! >> >> On 11/07/2012 09:11 AM, Kees Cook wrote: >>> Hrm, I don't like this. get_random_int() specifically says: "Get a >>> random word for internal kernel use only." The intent of AT_RANDOM is >>> for userspace pRNG seeding (though glibc currently uses it directly >>> for stack protector and pointer mangling), which is not "internal >>> kernel use only". :) Though I suppose this is already being used for >>> the randomize_stack_top(), but I think it'd still be better to use >>> higher quality bits. >> Btw Kees, does it sounds make sense if we just return the 16 bytes >> uninitialized stack array if the user disable the stack randomize via >> "/proc/sys/kernel/randomize_va_space = 0" or via the related sysctl, or >> even specified norandmaps on boot? > > No, I feel that ASLR (randomize_va_space) is distinctly separate from > how glibc uses AT_RANDOM (stack protector and pointer mangling). > AT_RANDOM should remain active even if randomize_va_space is 0. Ok, I was confused about the semantics of ASLR, thanks for your clarification, will post another patch soon according to your feedback.
-Jeff
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