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    SubjectRe: [RFC][PATCH] Randomize kernel base address on boot
    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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