linux/arch/x86
Thomas Garnier 0483e1fa6e x86/mm: Implement ASLR for kernel memory regions
Randomizes the virtual address space of kernel memory regions for
x86_64. This first patch adds the infrastructure and does not randomize
any region. The following patches will randomize the physical memory
mapping, vmalloc and vmemmap regions.

This security feature mitigates exploits relying on predictable kernel
addresses. These addresses can be used to disclose the kernel modules
base addresses or corrupt specific structures to elevate privileges
bypassing the current implementation of KASLR. This feature can be
enabled with the CONFIG_RANDOMIZE_MEMORY option.

The order of each memory region is not changed. The feature looks at the
available space for the regions based on different configuration options
and randomizes the base and space between each. The size of the physical
memory mapping is the available physical memory. No performance impact
was detected while testing the feature.

Entropy is generated using the KASLR early boot functions now shared in
the lib directory (originally written by Kees Cook). Randomization is
done on PGD & PUD page table levels to increase possible addresses. The
physical memory mapping code was adapted to support PUD level virtual
addresses. This implementation on the best configuration provides 30,000
possible virtual addresses in average for each memory region.  An
additional low memory page is used to ensure each CPU can start with a
PGD aligned virtual address (for realmode).

x86/dump_pagetable was updated to correctly display each region.

Updated documentation on x86_64 memory layout accordingly.

Performance data, after all patches in the series:

Kernbench shows almost no difference (-+ less than 1%):

Before:

Average Optimal load -j 12 Run (std deviation): Elapsed Time 102.63 (1.2695)
User Time 1034.89 (1.18115) System Time 87.056 (0.456416) Percent CPU 1092.9
(13.892) Context Switches 199805 (3455.33) Sleeps 97907.8 (900.636)

After:

Average Optimal load -j 12 Run (std deviation): Elapsed Time 102.489 (1.10636)
User Time 1034.86 (1.36053) System Time 87.764 (0.49345) Percent CPU 1095
(12.7715) Context Switches 199036 (4298.1) Sleeps 97681.6 (1031.11)

Hackbench shows 0% difference on average (hackbench 90 repeated 10 times):

attemp,before,after 1,0.076,0.069 2,0.072,0.069 3,0.066,0.066 4,0.066,0.068
5,0.066,0.067 6,0.066,0.069 7,0.067,0.066 8,0.063,0.067 9,0.067,0.065
10,0.068,0.071 average,0.0677,0.0677

Signed-off-by: Thomas Garnier <thgarnie@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Lv Zheng <lv.zheng@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: kernel-hardening@lists.openwall.com
Cc: linux-doc@vger.kernel.org
Link: http://lkml.kernel.org/r/1466556426-32664-6-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-08 17:33:46 +02:00
..
boot x86/mm: Refactor KASLR entropy functions 2016-07-08 17:33:45 +02:00
configs arch/defconfig: remove CONFIG_RESOURCE_COUNTERS 2016-05-23 17:04:14 -07:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2016-05-20 10:25:16 -07:00
entry x86/vdso: Add mremap hook to vm_special_mapping 2016-07-08 14:17:51 +02:00
events perf/x86/intel/uncore: Remove SBOX support for Broadwell server 2016-06-03 08:39:38 +02:00
ia32 mm: remove more IS_ERR_VALUE abuses 2016-05-27 15:57:31 -07:00
include x86/mm: Implement ASLR for kernel memory regions 2016-07-08 17:33:46 +02:00
kernel x86/mm: Implement ASLR for kernel memory regions 2016-07-08 17:33:46 +02:00
kvm KVM: nVMX: VMX instructions: fix segment checks when L1 is in long mode. 2016-06-27 15:30:44 +02:00
lguest x86/paravirt: Remove paravirt_enabled() 2016-04-22 10:29:07 +02:00
lib x86/mm: Refactor KASLR entropy functions 2016-07-08 17:33:45 +02:00
math-emu Merge branch 'x86-headers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-11-03 21:05:40 -08:00
mm x86/mm: Implement ASLR for kernel memory regions 2016-07-08 17:33:46 +02:00
net bpf, x86: add support for constant blinding 2016-05-16 13:49:32 -04:00
oprofile x86/cpufeature: Replace cpu_has_apic with boot_cpu_has() usage 2016-04-13 11:37:41 +02:00
pci xen: bug fixes for 4.7-rc0 2016-05-24 10:22:34 -07:00
platform x86/efi: get rid of superfluous __GFP_REPEAT 2016-06-24 17:23:52 -07:00
power x86/cpufeature: Remove cpu_has_pse 2016-03-31 13:35:10 +02:00
purgatory kbuild: delete unnecessary "@:" 2016-04-20 10:36:57 +02:00
ras x86/RAS: Add SMCA support to AMD Error Injector 2016-05-12 09:08:23 +02:00
realmode x86/mm: Separate variable for trampoline PGD 2016-07-08 17:33:46 +02:00
tools x86/KASLR: Clean up unused code from old 'run_size' and rename it to 'kernel_total_size' 2016-04-29 11:03:30 +02:00
um Merge branch 'for-linus-4.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2016-05-27 18:54:59 -07:00
video x86/video: Don't assume all FB devices are PCI devices 2016-03-15 11:08:26 +01:00
xen Merge branch 'akpm' (patches from Andrew) 2016-06-24 19:08:33 -07:00
.gitignore
Kbuild perf/x86: Move perf_event.c ............... => x86/events/core.c 2016-02-09 10:23:49 +01:00
Kconfig x86/mm: Implement ASLR for kernel memory regions 2016-07-08 17:33:46 +02:00
Kconfig.cpu x86/Kconfig/cpus: Fix/complete CPU type help texts 2015-10-21 11:12:56 +02:00
Kconfig.debug Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-03-15 09:32:27 -07:00
Makefile x86/init: Rename EBDA code file 2016-04-22 10:29:07 +02:00
Makefile.um
Makefile_32.cpu