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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 00/27] x86: PIE support and option to extend KASLR randomization
On Thu, Oct 12, 2017 at 9:28 AM, Tom Lendacky <thomas.lendacky@xxxxxxx> wrote: > On 10/12/2017 10:34 AM, Thomas Garnier wrote: >> >> On Wed, Oct 11, 2017 at 2:34 PM, Tom Lendacky <thomas.lendacky@xxxxxxx> >> wrote: >>> >>> On 10/11/2017 3:30 PM, Thomas Garnier wrote: >>>> >>>> Changes: >>>> - patch v1: >>>> - Simplify ftrace implementation. >>>> - Use gcc mstack-protector-guard-reg=%gs with PIE when possible. >>>> - rfc v3: >>>> - Use --emit-relocs instead of -pie to reduce dynamic relocation >>>> space on >>>> mapped memory. It also simplifies the relocation process. >>>> - Move the start the module section next to the kernel. Remove the >>>> need for >>>> -mcmodel=large on modules. Extends module space from 1 to 2G >>>> maximum. >>>> - Support for XEN PVH as 32-bit relocations can be ignored with >>>> --emit-relocs. >>>> - Support for GOT relocations previously done automatically with >>>> -pie. >>>> - Remove need for dynamic PLT in modules. >>>> - Support dymamic GOT for modules. >>>> - rfc v2: >>>> - Add support for global stack cookie while compiler default to fs >>>> without >>>> mcmodel=kernel >>>> - Change patch 7 to correctly jump out of the identity mapping on >>>> kexec load >>>> preserve. >>>> >>>> These patches make the changes necessary to build the kernel as Position >>>> Independent Executable (PIE) on x86_64. A PIE kernel can be relocated >>>> below >>>> the top 2G of the virtual address space. It allows to optionally extend >>>> the >>>> KASLR randomization range from 1G to 3G. >>> >>> >>> Hi Thomas, >>> >>> I've applied your patches so that I can verify that SME works with PIE. >>> Unfortunately, I'm running into build warnings and errors when I enable >>> PIE. >>> >>> With CONFIG_STACK_VALIDATION=y I receive lots of messages like this: >>> >>> drivers/scsi/libfc/fc_exch.o: warning: objtool: >>> fc_destroy_exch_mgr()+0x0: call without frame pointer save/setup >>> >>> Disabling CONFIG_STACK_VALIDATION suppresses those. >> >> >> I ran into that, I plan to fix it in the next iteration. >> >>> >>> But near the end of the build, I receive errors like this: >>> >>> arch/x86/kernel/setup.o: In function `dump_kernel_offset': >>> .../arch/x86/kernel/setup.c:801:(.text+0x32): relocation truncated to >>> fit: R_X86_64_32S against symbol `_text' defined in .text section in >>> .tmp_vmlinux1 >>> . >>> . about 10 more of the above type messages >>> . >>> make: *** [vmlinux] Error 1 >>> Error building kernel, exiting >>> >>> Are there any config options that should or should not be enabled when >>> building with PIE enabled? Is there a compiler requirement for PIE (I'm >>> using gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.5))? >> >> >> I never ran into these ones and I tested compilers older and newer. >> What was your exact configuration? > > > I'll send you the config in a separate email. > > Thanks, > Tom Thanks for your feedback (Tom and Markus). The issue was linked to using a modern gcc with a modern linker, I managed to repro and fix it on my current version. I will create a v1.5 for Kees Cook to keep on one of his branch for few weeks so I can collect as much feedback from 0day. After that I will send v2. > > >> >>> >>> Thanks, >>> Tom >>> >>>> >>>> Thanks a lot to Ard Biesheuvel & Kees Cook on their feedback on compiler >>>> changes, PIE support and KASLR in general. Thanks to Roland McGrath on >>>> his >>>> feedback for using -pie versus --emit-relocs and details on compiler >>>> code >>>> generation. >>>> >>>> The patches: >>>> - 1-3, 5-1#, 17-18: Change in assembly code to be PIE compliant. >>>> - 4: Add a new _ASM_GET_PTR macro to fetch a symbol address >>>> generically. >>>> - 14: Adapt percpu design to work correctly when PIE is enabled. >>>> - 15: Provide an option to default visibility to hidden except for >>>> key symbols. >>>> It removes errors between compilation units. >>>> - 16: Adapt relocation tool to handle PIE binary correctly. >>>> - 19: Add support for global cookie. >>>> - 20: Support ftrace with PIE (used on Ubuntu config). >>>> - 21: Fix incorrect address marker on dump_pagetables. >>>> - 22: Add option to move the module section just after the kernel. >>>> - 23: Adapt module loading to support PIE with dynamic GOT. >>>> - 24: Make the GOT read-only. >>>> - 25: Add the CONFIG_X86_PIE option (off by default). >>>> - 26: Adapt relocation tool to generate a 64-bit relocation table. >>>> - 27: Add the CONFIG_RANDOMIZE_BASE_LARGE option to increase >>>> relocation range >>>> from 1G to 3G (off by default). >>>> >>>> Performance/Size impact: >>>> >>>> Size of vmlinux (Default configuration): >>>> File size: >>>> - PIE disabled: +0.000031% >>>> - PIE enabled: -3.210% (less relocations) >>>> .text section: >>>> - PIE disabled: +0.000644% >>>> - PIE enabled: +0.837% >>>> >>>> Size of vmlinux (Ubuntu configuration): >>>> File size: >>>> - PIE disabled: -0.201% >>>> - PIE enabled: -0.082% >>>> .text section: >>>> - PIE disabled: same >>>> - PIE enabled: +1.319% >>>> >>>> Size of vmlinux (Default configuration + ORC): >>>> File size: >>>> - PIE enabled: -3.167% >>>> .text section: >>>> - PIE enabled: +0.814% >>>> >>>> Size of vmlinux (Ubuntu configuration + ORC): >>>> File size: >>>> - PIE enabled: -3.167% >>>> .text section: >>>> - PIE enabled: +1.26% >>>> >>>> The size increase is mainly due to not having access to the 32-bit >>>> signed >>>> relocation that can be used with mcmodel=kernel. A small part is due to >>>> reduced >>>> optimization for PIE code. This bug [1] was opened with gcc to provide a >>>> better >>>> code generation for kernel PIE. >>>> >>>> Hackbench (50% and 1600% on thread/process for pipe/sockets): >>>> - PIE disabled: no significant change (avg +0.1% on latest test). >>>> - PIE enabled: between -0.50% to +0.86% in average (default and >>>> Ubuntu config). >>>> >>>> slab_test (average of 10 runs): >>>> - PIE disabled: no significant change (-2% on latest run, likely >>>> noise). >>>> - PIE enabled: between -1% and +0.8% on latest runs. >>>> >>>> Kernbench (average of 10 Half and Optimal runs): >>>> Elapsed Time: >>>> - PIE disabled: no significant change (avg -0.239%) >>>> - PIE enabled: average +0.07% >>>> System Time: >>>> - PIE disabled: no significant change (avg -0.277%) >>>> - PIE enabled: average +0.7% >>>> >>>> [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82303 >>>> >>>> diffstat: >>>> Documentation/x86/x86_64/mm.txt | 3 >>>> arch/x86/Kconfig | 43 ++++++ >>>> arch/x86/Makefile | 40 +++++ >>>> arch/x86/boot/boot.h | 2 >>>> arch/x86/boot/compressed/Makefile | 5 >>>> arch/x86/boot/compressed/misc.c | 10 + >>>> arch/x86/crypto/aes-x86_64-asm_64.S | 45 ++++-- >>>> arch/x86/crypto/aesni-intel_asm.S | 14 +- >>>> arch/x86/crypto/aesni-intel_avx-x86_64.S | 6 >>>> arch/x86/crypto/camellia-aesni-avx-asm_64.S | 42 +++--- >>>> arch/x86/crypto/camellia-aesni-avx2-asm_64.S | 44 +++--- >>>> arch/x86/crypto/camellia-x86_64-asm_64.S | 8 - >>>> arch/x86/crypto/cast5-avx-x86_64-asm_64.S | 50 ++++--- >>>> arch/x86/crypto/cast6-avx-x86_64-asm_64.S | 44 +++--- >>>> arch/x86/crypto/des3_ede-asm_64.S | 96 +++++++++----- >>>> arch/x86/crypto/ghash-clmulni-intel_asm.S | 4 >>>> arch/x86/crypto/glue_helper-asm-avx.S | 4 >>>> arch/x86/crypto/glue_helper-asm-avx2.S | 6 >>>> arch/x86/entry/entry_32.S | 3 >>>> arch/x86/entry/entry_64.S | 29 ++-- >>>> arch/x86/include/asm/asm.h | 13 + >>>> arch/x86/include/asm/bug.h | 2 >>>> arch/x86/include/asm/ftrace.h | 6 >>>> arch/x86/include/asm/jump_label.h | 8 - >>>> arch/x86/include/asm/kvm_host.h | 6 >>>> arch/x86/include/asm/module.h | 11 + >>>> arch/x86/include/asm/page_64_types.h | 9 + >>>> arch/x86/include/asm/paravirt_types.h | 12 + >>>> arch/x86/include/asm/percpu.h | 25 ++- >>>> arch/x86/include/asm/pgtable_64_types.h | 6 >>>> arch/x86/include/asm/pm-trace.h | 2 >>>> arch/x86/include/asm/processor.h | 12 + >>>> arch/x86/include/asm/sections.h | 8 + >>>> arch/x86/include/asm/setup.h | 2 >>>> arch/x86/include/asm/stackprotector.h | 19 ++ >>>> arch/x86/kernel/acpi/wakeup_64.S | 31 ++-- >>>> arch/x86/kernel/asm-offsets.c | 3 >>>> arch/x86/kernel/asm-offsets_32.c | 3 >>>> arch/x86/kernel/asm-offsets_64.c | 3 >>>> arch/x86/kernel/cpu/common.c | 7 - >>>> arch/x86/kernel/cpu/microcode/core.c | 4 >>>> arch/x86/kernel/ftrace.c | 42 +++++- >>>> arch/x86/kernel/head64.c | 32 +++- >>>> arch/x86/kernel/head_32.S | 3 >>>> arch/x86/kernel/head_64.S | 41 +++++- >>>> arch/x86/kernel/kvm.c | 6 >>>> arch/x86/kernel/module.c | 182 >>>> ++++++++++++++++++++++++++- >>>> arch/x86/kernel/module.lds | 3 >>>> arch/x86/kernel/process.c | 5 >>>> arch/x86/kernel/relocate_kernel_64.S | 8 - >>>> arch/x86/kernel/setup_percpu.c | 2 >>>> arch/x86/kernel/vmlinux.lds.S | 13 + >>>> arch/x86/kvm/svm.c | 4 >>>> arch/x86/lib/cmpxchg16b_emu.S | 8 - >>>> arch/x86/mm/dump_pagetables.c | 11 + >>>> arch/x86/power/hibernate_asm_64.S | 4 >>>> arch/x86/tools/relocs.c | 170 >>>> +++++++++++++++++++++++-- >>>> arch/x86/tools/relocs.h | 4 >>>> arch/x86/tools/relocs_common.c | 15 +- >>>> arch/x86/xen/xen-asm.S | 12 - >>>> arch/x86/xen/xen-head.S | 9 - >>>> arch/x86/xen/xen-pvh.S | 13 + >>>> drivers/base/firmware_class.c | 4 >>>> include/asm-generic/sections.h | 6 >>>> include/asm-generic/vmlinux.lds.h | 12 + >>>> include/linux/compiler.h | 8 + >>>> init/Kconfig | 9 + >>>> kernel/kallsyms.c | 16 +- >>>> kernel/trace/trace.h | 4 >>>> lib/dynamic_debug.c | 4 >>>> 70 files changed, 1032 insertions(+), 308 deletions(-) >>>> >> >> >> > -- Thomas _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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