Messages in this thread | | | Date | Thu, 26 May 2011 16:55:49 -0400 | From | Vivek Goyal <> | Subject | Re: [RFC][PATCH] Randomize kernel base address on boot |
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On Thu, May 26, 2011 at 04:44:34PM -0400, Dan Rosenberg wrote: > On Thu, 2011-05-26 at 16:40 -0400, Vivek Goyal wrote: > > On Thu, May 26, 2011 at 04:35:02PM -0400, Vivek Goyal wrote: > > > On Tue, May 24, 2011 at 04:31:45PM -0400, Dan Rosenberg wrote: > > > > This introduces CONFIG_RANDOMIZE_BASE, which randomizes the address at > > > > which the kernel is decompressed at boot as a security feature that > > > > deters exploit attempts relying on knowledge of the location of kernel > > > > internals. The default values of the kptr_restrict and dmesg_restrict > > > > sysctls are set to (1) when this is enabled, since hiding kernel > > > > pointers is necessary to preserve the secrecy of the randomized base > > > > address. > > > > > > What happens to /proc/iomem interface which gives us the physical memory > > > location where kernel is loaded. kexec-tools relies on that interface > > > heavily so we can not take it away. And if we can not take it away then > > > I think somebody should be easibly be able to calculate this randomized > > > base address. > > Is it common to run kexec-tools as non-root? It may be necessary to > restrict this interface to root when randomization is used (keep in mind > nobody's going to force you to turn this on by default, at least for the > foreseeable future).
kexec-tools runs as root. And I see that /proc/iomem permissions are also for root only. So it probably is a non-issue.
Thanks Vivek
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