[PATCH v17 23/26] ELF: Introduce arch_setup_elf_property()
From: Yu-cheng Yu <hidden>
Date: 2020-12-29 21:34:22
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
arm64 port (aarch64 architecture), exec & binfmt api, elf, filesystems (vfs and infrastructure), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Catalin Marinas, Will Deacon, Kees Cook, Alexander Viro, Christian Brauner, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
An ELF file's .note.gnu.property indicates arch features supported by the file. These features are extracted by arch_parse_elf_property() and stored in 'arch_elf_state'. Introduce arch_setup_elf_property() for enabling such features. The first use-case of this function is shadow stack. ARM64 is the other arch that has ARCH_USER_GNU_PROPERTY and arch_parse_elf_ property(). Add arch_setup_elf_property() for it. Signed-off-by: Yu-cheng Yu <redacted> Cc: Mark Brown <broonie@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Martin <Dave.Martin@arm.com> --- arch/arm64/include/asm/elf.h | 5 +++++ arch/x86/Kconfig | 2 ++ arch/x86/include/asm/elf.h | 13 +++++++++++++ arch/x86/kernel/process_64.c | 32 ++++++++++++++++++++++++++++++++ fs/binfmt_elf.c | 4 ++++ include/linux/elf.h | 6 ++++++ 6 files changed, 62 insertions(+)
diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 8d1c8dcb87fd..d37bc7915935 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h@@ -281,6 +281,11 @@ static inline int arch_parse_elf_property(u32 type, const void *data, return 0; } +static inline int arch_setup_elf_property(struct arch_elf_state *arch) +{ + return 0; +} + static inline int arch_elf_pt_proc(void *ehdr, void *phdr, struct file *f, bool is_interp, struct arch_elf_state *state)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index fdaa437d9c53..b26c79c87558 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -1964,6 +1964,8 @@ config X86_CET_USER select ARCH_USES_HIGH_VMA_FLAGS select ARCH_HAS_SHADOW_STACK select ARCH_MAYBE_MKWRITE + select ARCH_USE_GNU_PROPERTY + select ARCH_BINFMT_ELF_STATE help Control-flow protection is a hardware security hardening feature that detects function-return address or jump target changes by
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 66bdfe838d61..13701eaa521c 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h@@ -390,6 +390,19 @@ extern int compat_arch_setup_additional_pages(struct linux_binprm *bprm, extern bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs); +#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 ad582f9ac5a6..2e8decf79f8c 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c@@ -835,3 +835,35 @@ 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; + + if (!IS_ENABLED(CONFIG_X86_CET_USER)) + return r; + + 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(); + } + + return r; +} +#endif
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 950bc177238a..5d5f6a54a035 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c@@ -1245,6 +1245,10 @@ static int load_elf_binary(struct linux_binprm *bprm) set_binfmt(&elf_format); + retval = arch_setup_elf_property(&arch_state); + if (retval < 0) + goto out; + #ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES retval = ARCH_SETUP_ADDITIONAL_PAGES(bprm, elf_ex, !!interpreter); if (retval < 0)
diff --git a/include/linux/elf.h b/include/linux/elf.h
index c9a46c4e183b..be04d15e937f 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h@@ -92,9 +92,15 @@ static inline int arch_parse_elf_property(u32 type, const void *data, { return 0; } + +static inline int arch_setup_elf_property(struct arch_elf_state *arch) +{ + return 0; +} #else extern int arch_parse_elf_property(u32 type, const void *data, size_t datasz, bool compat, struct arch_elf_state *arch); +extern int arch_setup_elf_property(struct arch_elf_state *arch); #endif #ifdef CONFIG_ARCH_HAVE_ELF_PROT
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2.21.0