[PATCH 00/30] implement KASLR for ARM
Ard Biesheuvel
ard.biesheuvel at linaro.org
Mon Aug 14 05:53:41 PDT 2017
This series implements randomization of the placement of the core ARM kernel
inside the lowmem region. It consists of the following parts:
- changes that allow us to build vmlinux as a PIE executable which retains
the metadata required to fix up all absolute symbol references at runtime
- changes that eliminate absolute references from low-level code that may
execute with the MMU off: this removes the need to perform explicit cache
maintenance after the absolute references have been fixed up at runtime with
the caches enabled
- changes to the core kernel startup code to take the physical offset into
account when creating the virtual mapping (the pa-to-va mapping remains
unchanged)
- changes to the decompressor to take the KASLR offset into account when
placing the kernel in physical memory
- changes to the UEFI stub code to choose the KASLR offset and communicate
it to the decompressor
Bootloader changes required for other boot environments are left as an
exercise for the reader.
To test these changes, get a UEFI image for QEMU here [0] and boot a
multi_v7_defconfig+CONFIG_RANDOMIZE_BASE=y build using:
qemu-system-aarch64 -M virt -m 2048 -bios QEMU_EFI.fd -kernel zImage \
-device virtio-rng-pci -net none -nographic -append earlycon
and expect to see something like
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB)
[ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB)
[ 0.000000] vmalloc : 0xf0800000 - 0xff800000 ( 240 MB)
[ 0.000000] lowmem : 0xc0000000 - 0xf0000000 ( 768 MB)
[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB)
[ 0.000000] modules : 0xbf800000 - 0xbfe00000 ( 6 MB)
[ 0.000000] .text : 0xd4208000 - 0xd4c00000 (10208 kB) <----
[ 0.000000] .init : 0xd5200000 - 0xd5600000 (4096 kB) <----
[ 0.000000] .data : 0xd5600000 - 0xd5776f28 (1500 kB) <----
[ 0.000000] .bss : 0xd57805e0 - 0xd57e60ac ( 407 kB) <----
[0] https://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-ARM/RELEASE_GCC49/QEMU_EFI.fd
(or update patch #26 to poke a hardcoded value into kaslr_offset directly)
Note that this series partially overlaps with my series 'ARM: add and use
convenience macros for PC relative references', for which I will not send
a follow up. I kept the necessary ones, and dropped some others that are
not actually that useful in the context of KASLR.
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Nicolas Pitre <nico at linaro.org>
Cc: Russell King <linux at armlinux.org.uk>
Cc: Kees Cook <keescook at chromium.org>
Cc: Thomas Garnier <thgarnie at google.com>
Cc: Marc Zyngier <marc.zyngier at arm.com>
Cc: Mark Rutland <mark.rutland at arm.com>
Cc: Tony Lindgren <tony at atomide.com>
Cc: Matt Fleming <matt at codeblueprint.co.uk>
Cc: Dave Martin <dave.martin at arm.com>
Ard Biesheuvel (30):
asm-generic: add .data.rel.ro sections to __ro_after_init
ARM: assembler: introduce adr_l, ldr_l and str_l macros
ARM: head-common.S: use PC-relative insn sequence for __proc_info
ARM: head-common.S: use PC-relative insn sequence for idmap creation
ARM: head.S: use PC-relative insn sequence for secondary_data
ARM: kernel: use relative references for UP/SMP alternatives
ARM: head: use PC-relative insn sequence for __smp_alt
ARM: sleep.S: use PC-relative insn sequence for
sleep_save_sp/mpidr_hash
ARM: head.S: use PC-relative insn sequences for __fixup_pv_table
ARM: head.S: use PC relative insn sequence to calculate PHYS_OFFSET
ARM: kvm: replace open coded VA->PA calculations with adr_l call
arm-soc: exynos: replace open coded VA->PA conversions
arm-soc: mvebu: replace open coded VA->PA conversion
arm-soc: various: replace open coded VA->PA calculation of pen_release
ARM: kernel: switch to relative exception tables
ARM: kernel: use relative phys-to-virt patch tables
arm-soc: tegra: make sleep asm code runtime relocatable
ARM: kernel: make vmlinux buildable as a PIE executable
ARM: kernel: use PC-relative symbol references in MMU switch code
ARM: kernel: use PC relative symbol references in suspend/resume code
ARM: mm: export default vmalloc base address
ARM: kernel: refer to swapper_pg_dir via its symbol
ARM: kernel: implement randomization of the kernel load address
ARM: decompressor: explicitly map decompressor binary cacheable
ARM: compressed: factor out zImage header and make it extensible
ARM: decompressor: add KASLR support
efi/libstub: add 'max' parameter to efi_random_alloc()
efi/libstub: check for vmalloc= command line argument
efi/libstub: arm: reserve bootloader supplied initrd in memory map
efi/libstub: arm: implement KASLR
arch/arm/Kconfig | 19 ++
arch/arm/Makefile | 5 +
arch/arm/boot/compressed/head.S | 46 ++---
arch/arm/boot/compressed/vmlinux.lds.S | 5 +-
arch/arm/include/asm/Kbuild | 1 -
arch/arm/include/asm/assembler.h | 86 +++++++-
arch/arm/include/asm/extable.h | 20 ++
arch/arm/include/asm/futex.h | 2 +-
arch/arm/include/asm/memory.h | 6 +-
arch/arm/include/asm/pgtable.h | 1 +
arch/arm/include/asm/processor.h | 2 +-
arch/arm/include/asm/uaccess.h | 8 +-
arch/arm/include/asm/word-at-a-time.h | 2 +-
arch/arm/include/asm/zimage.h | 65 ++++++
arch/arm/kernel/entry-armv.S | 6 +-
arch/arm/kernel/head-common.S | 61 ++----
arch/arm/kernel/head.S | 217 ++++++++++++--------
arch/arm/kernel/hyp-stub.S | 33 ++-
arch/arm/kernel/sleep.S | 27 +--
arch/arm/kernel/swp_emulate.c | 4 +-
arch/arm/kernel/vmlinux.lds.S | 9 +
arch/arm/kvm/init.S | 8 +-
arch/arm/lib/backtrace.S | 8 +-
arch/arm/lib/getuser.S | 22 +-
arch/arm/lib/putuser.S | 12 +-
arch/arm/mach-exynos/headsmp.S | 9 +-
arch/arm/mach-exynos/sleep.S | 26 +--
arch/arm/mach-mvebu/coherency_ll.S | 8 +-
arch/arm/mach-prima2/headsmp.S | 11 +-
arch/arm/mach-spear/headsmp.S | 11 +-
arch/arm/mach-sti/headsmp.S | 10 +-
arch/arm/mach-tegra/sleep-tegra20.S | 22 +-
arch/arm/mach-tegra/sleep-tegra30.S | 6 +-
arch/arm/mach-tegra/sleep.S | 4 +-
arch/arm/mm/alignment.c | 14 +-
arch/arm/mm/extable.c | 2 +-
arch/arm/mm/mmu.c | 3 +-
arch/arm/nwfpe/entry.S | 2 +-
arch/arm/plat-versatile/headsmp.S | 9 +-
drivers/firmware/efi/libstub/arm-stub.c | 51 +++--
drivers/firmware/efi/libstub/arm32-stub.c | 46 ++++-
drivers/firmware/efi/libstub/arm64-stub.c | 2 +-
drivers/firmware/efi/libstub/efi-stub-helper.c | 9 +
drivers/firmware/efi/libstub/efistub.h | 7 +-
drivers/firmware/efi/libstub/fdt.c | 42 ++++
drivers/firmware/efi/libstub/random.c | 10 +-
include/asm-generic/vmlinux.lds.h | 2 +-
include/linux/hidden.h | 21 ++
scripts/sortextable.c | 2 +-
49 files changed, 636 insertions(+), 368 deletions(-)
create mode 100644 arch/arm/include/asm/extable.h
create mode 100644 arch/arm/include/asm/zimage.h
create mode 100644 include/linux/hidden.h
--
2.11.0
More information about the linux-arm-kernel
mailing list