[RFC PATCH v9 24/27] x86/cet/shstk: ELF header parsing for Shadow Stack
From: Yu-cheng Yu <hidden>
Date: 2020-02-05 18:20:56
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
Check an ELF file's .note.gnu.property, and setup Shadow Stack if the application supports it. v9: - Change cpu_feature_enabled() to static_cpu_has(). Signed-off-by: Yu-cheng Yu <redacted> --- arch/x86/Kconfig | 2 ++ arch/x86/include/asm/elf.h | 13 +++++++++++++ arch/x86/kernel/process_64.c | 31 +++++++++++++++++++++++++++++++ 3 files changed, 46 insertions(+)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6c34b701c588..d1447380e02e 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -1987,6 +1987,8 @@ config X86_INTEL_SHADOW_STACK_USER select ARCH_USES_HIGH_VMA_FLAGS select X86_INTEL_CET select ARCH_HAS_SHSTK + select ARCH_USE_GNU_PROPERTY + select ARCH_BINFMT_ELF_STATE ---help--- Shadow Stack (SHSTK) provides protection against program stack corruption. It is active when the kernel has this
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 69c0f892e310..fac79b621e0a 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h@@ -367,6 +367,19 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp); #define compat_arch_setup_additional_pages compat_arch_setup_additional_pages +#ifdef CONFIG_ARCH_BINFMT_ELF_STATE +struct arch_elf_state { + unsigned int gnu_property; +}; + +#define INIT_ARCH_ELF_STATE { \ + .gnu_property = 0, \ +} + +#define arch_elf_pt_proc(ehdr, phdr, elf, interp, state) (0) +#define arch_check_elf(ehdr, interp, interp_ehdr, state) (0) +#endif + /* Do not change the values. See get_align_mask() */ enum align_flags { ALIGN_VA_32 = BIT(0),
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 506d66830d4d..99548cde0cc6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c@@ -732,3 +732,34 @@ unsigned long KSTK_ESP(struct task_struct *task) { return task_pt_regs(task)->sp; } + +#ifdef CONFIG_ARCH_USE_GNU_PROPERTY +int arch_parse_elf_property(u32 type, const void *data, size_t datasz, + bool compat, struct arch_elf_state *state) +{ + if (type != GNU_PROPERTY_X86_FEATURE_1_AND) + return 0; + + if (datasz != sizeof(unsigned int)) + return -ENOEXEC; + + state->gnu_property = *(unsigned int *)data; + return 0; +} + +int arch_setup_elf_property(struct arch_elf_state *state) +{ + int r = 0; + + memset(¤t->thread.cet, 0, sizeof(struct cet_status)); + + if (static_cpu_has(X86_FEATURE_SHSTK)) { + if (state->gnu_property & GNU_PROPERTY_X86_FEATURE_1_SHSTK) + r = cet_setup_shstk(); + if (r < 0) + return r; + } + + return r; +} +#endif
--
2.21.0