Re: [PATCH v6 00/12] implement KASLR for powerpc/fsl_booke/32

[Jason Yan]

A polite ping :)

What else should I do now?

Thanks

On 2019/8/19 14:12, Jason Yan wrote:
> Hi Michael,
>
> Is there anything more I should do to get this feature meeting the 
> requirements of the mainline?
>
> Thanks,
> Jason
>
> On 2019/8/9 18:07, Jason Yan wrote:
> > This series implements KASLR for powerpc/fsl_booke/32, as a security
> > feature that deters exploit attempts relying on knowledge of the location
> > of kernel internals.
> >
> > Since CONFIG_RELOCATABLE has already supported, what we need to do is
> > map or copy kernel to a proper place and relocate. Freescale Book-E
> > parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1
> > entries are not suitable to map the kernel directly in a randomized
> > region, so we chose to copy the kernel to a proper place and restart to
> > relocate.
> >
> > Entropy is derived from the banner and timer base, which will change 
> > every
> > build and boot. This not so much safe so additionally the bootloader may
> > pass entropy via the /chosen/kaslr-seed node in device tree.
> >
> > We will use the first 512M of the low memory to randomize the kernel
> > image. The memory will be split in 64M zones. We will use the lower 8
> > bit of the entropy to decide the index of the 64M zone. Then we chose a
> > 16K aligned offset inside the 64M zone to put the kernel in.
> >
> > ÂÂÂÂ KERNELBASE
> >
> > ÂÂÂÂÂÂÂÂ |-->ÂÂ 64MÂÂ <--|
> > ÂÂÂÂÂÂÂÂ |ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |
> > ÂÂÂÂÂÂÂÂ +---------------+ÂÂÂ +----------------+---------------+
> > ÂÂÂÂÂÂÂÂ |ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |....|ÂÂÂ |kernel|ÂÂÂ |ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |
> > ÂÂÂÂÂÂÂÂ +---------------+ÂÂÂ +----------------+---------------+
> > ÂÂÂÂÂÂÂÂ |ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |
> > ÂÂÂÂÂÂÂÂ |----->ÂÂ offsetÂÂÂ <-----|
> >
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ kernstart_virt_addr
> >
> > We also check if we will overlap with some areas like the dtb area, the
> > initrd area or the crashkernel area. If we cannot find a proper area,
> > kaslr will be disabled and boot from the original kernel.
> >
> > Changes since v5:
> > Â - Rename M_IF_NEEDED to MAS2_M_IF_NEEDED
> > Â - Define some global variable as __ro_after_init
> > Â - Replace kimage_vaddr with kernstart_virt_addr
> > Â - Depend on RELOCATABLE, not select it
> > Â - Modify the comment block below the SPDX tag
> > Â - Remove some useless headers in kaslr_booke.c and move is_second_reloc
> > ÂÂÂ declarationto mmu_decl.h
> > Â - Remove DBG() and use pr_debug() and rewrite comment above 
> > get_boot_seed().
> > Â - Add a patch to document the KASLR implementation.
> > Â - Split a patch from patch #10 which exports kaslr offset in 
> > VMCOREINFO ELF notes.
> > Â - Remove extra logic around finding nokaslr string in cmdline.
> > Â - Make regions static global and __initdata
> >
> > Changes since v4:
> > Â - Add Reviewed-by tag from Christophe
> > Â - Remove an unnecessary cast
> > Â - Remove unnecessary parenthesis
> > Â - Fix checkpatch warning
> >
> > Changes since v3:
> > Â - Add Reviewed-by and Tested-by tag from Diana
> > Â - Change the comment in fsl_booke_entry_mapping.S to be consistent
> > ÂÂÂ with the new code.
> >
> > Changes since v2:
> > Â - Remove unnecessary #ifdef
> > Â - Use SZ_64M instead of0x4000000
> > Â - Call early_init_dt_scan_chosen() to init boot_command_line
> > Â - Rename kaslr_second_init() to kaslr_late_init()
> >
> > Changes since v1:
> > Â - Remove some useless 'extern' keyword.
> > Â - Replace EXPORT_SYMBOL with EXPORT_SYMBOL_GPL
> > Â - Improve some assembly code
> > Â - Use memzero_explicit instead of memset
> > Â - Use boot_command_line and remove early_command_line
> > Â - Do not print kaslr offset if kaslr is disabled
> >
> > Jason Yan (12):
> > ÂÂ powerpc: unify definition of M_IF_NEEDED
> > ÂÂ powerpc: move memstart_addr and kernstart_addr to init-common.c
> > ÂÂ powerpc: introduce kernstart_virt_addr to store the kernel base
> > ÂÂ powerpc/fsl_booke/32: introduce create_tlb_entry() helper
> > ÂÂ powerpc/fsl_booke/32: introduce reloc_kernel_entry() helper
> > ÂÂ powerpc/fsl_booke/32: implement KASLR infrastructure
> > ÂÂ powerpc/fsl_booke/32: randomize the kernel image offset
> > ÂÂ powerpc/fsl_booke/kaslr: clear the original kernel if randomized
> > ÂÂ powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter
> > ÂÂ powerpc/fsl_booke/kaslr: dump out kernel offset information on panic
> > ÂÂ powerpc/fsl_booke/kaslr: export offset in VMCOREINFO ELF notes
> > ÂÂ powerpc/fsl_booke/32: Document KASLR implementation
> >
> > Â Documentation/powerpc/kaslr-booke32.rstÂÂÂÂÂÂ |Â 42 ++
> > Â arch/powerpc/KconfigÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |Â 11 +
> >  arch/powerpc/include/asm/nohash/mmu-book3e.h | 10 +
> > Â arch/powerpc/include/asm/page.hÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 7 +
> > Â arch/powerpc/kernel/MakefileÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 1 +
> > Â arch/powerpc/kernel/early_32.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 2 +-
> > Â arch/powerpc/kernel/exceptions-64e.SÂÂÂÂÂÂÂÂÂ |Â 12 +-
> > Â arch/powerpc/kernel/fsl_booke_entry_mapping.S |Â 27 +-
> > Â arch/powerpc/kernel/head_fsl_booke.SÂÂÂÂÂÂÂÂÂ |Â 55 ++-
> > Â arch/powerpc/kernel/kaslr_booke.cÂÂÂÂÂÂÂÂÂÂÂÂ | 393 ++++++++++++++++++
> > Â arch/powerpc/kernel/machine_kexec.cÂÂÂÂÂÂÂÂÂÂ |ÂÂ 1 +
> > Â arch/powerpc/kernel/misc_64.SÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 7 +-
> > Â arch/powerpc/kernel/setup-common.cÂÂÂÂÂÂÂÂÂÂÂ |Â 20 +
> > Â arch/powerpc/mm/init-common.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 7 +
> > Â arch/powerpc/mm/init_32.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 5 -
> > Â arch/powerpc/mm/init_64.cÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 5 -
> > Â arch/powerpc/mm/mmu_decl.hÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ |Â 11 +
> > Â arch/powerpc/mm/nohash/fsl_booke.cÂÂÂÂÂÂÂÂÂÂÂ |ÂÂ 8 +-
> > Â 18 files changed, 572 insertions(+), 52 deletions(-)
> > Â create mode 100644 Documentation/powerpc/kaslr-booke32.rst
> > Â create mode 100644 arch/powerpc/kernel/kaslr_booke.c