diff options
Diffstat (limited to 'arch')
29 files changed, 222 insertions, 40 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index d9b4ae0fc805..266862428a84 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -744,11 +744,13 @@ config ARCH_SUPPORTS_CFI_CLANG An architecture should select this option if it can support Clang's Control-Flow Integrity (CFI) checking. +config ARCH_USES_CFI_TRAPS + bool + config CFI_CLANG bool "Use Clang's Control Flow Integrity (CFI)" - depends on LTO_CLANG && ARCH_SUPPORTS_CFI_CLANG - depends on CLANG_VERSION >= 140000 - select KALLSYMS + depends on ARCH_SUPPORTS_CFI_CLANG + depends on $(cc-option,-fsanitize=kcfi) help This option enables Clang’s forward-edge Control Flow Integrity (CFI) checking, where the compiler injects a runtime check to each @@ -760,16 +762,6 @@ config CFI_CLANG https://clang.llvm.org/docs/ControlFlowIntegrity.html -config CFI_CLANG_SHADOW - bool "Use CFI shadow to speed up cross-module checks" - default y - depends on CFI_CLANG && MODULES - help - If you select this option, the kernel builds a fast look-up table of - CFI check functions in loaded modules to reduce performance overhead. - - If unsure, say Y. - config CFI_PERMISSIVE bool "Use CFI in permissive mode" depends on CFI_CLANG diff --git a/arch/arm64/crypto/ghash-ce-core.S b/arch/arm64/crypto/ghash-ce-core.S index 7868330dd54e..ebe5558929b7 100644 --- a/arch/arm64/crypto/ghash-ce-core.S +++ b/arch/arm64/crypto/ghash-ce-core.S @@ -6,6 +6,7 @@ */ #include <linux/linkage.h> +#include <linux/cfi_types.h> #include <asm/assembler.h> SHASH .req v0 @@ -350,11 +351,11 @@ CPU_LE( rev64 T1.16b, T1.16b ) * void pmull_ghash_update(int blocks, u64 dg[], const char *src, * struct ghash_key const *k, const char *head) */ -SYM_FUNC_START(pmull_ghash_update_p64) +SYM_TYPED_FUNC_START(pmull_ghash_update_p64) __pmull_ghash p64 SYM_FUNC_END(pmull_ghash_update_p64) -SYM_FUNC_START(pmull_ghash_update_p8) +SYM_TYPED_FUNC_START(pmull_ghash_update_p8) __pmull_ghash p8 SYM_FUNC_END(pmull_ghash_update_p8) diff --git a/arch/arm64/crypto/sm3-ce-core.S b/arch/arm64/crypto/sm3-ce-core.S index ef97d3187cb7..ca70cfacd0d0 100644 --- a/arch/arm64/crypto/sm3-ce-core.S +++ b/arch/arm64/crypto/sm3-ce-core.S @@ -6,6 +6,7 @@ */ #include <linux/linkage.h> +#include <linux/cfi_types.h> #include <asm/assembler.h> .irp b, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 @@ -73,7 +74,7 @@ * int blocks) */ .text -SYM_FUNC_START(sm3_ce_transform) +SYM_TYPED_FUNC_START(sm3_ce_transform) /* load state */ ld1 {v8.4s-v9.4s}, [x0] rev64 v8.4s, v8.4s diff --git a/arch/arm64/include/asm/brk-imm.h b/arch/arm64/include/asm/brk-imm.h index ec7720dbe2c8..6e000113e508 100644 --- a/arch/arm64/include/asm/brk-imm.h +++ b/arch/arm64/include/asm/brk-imm.h @@ -17,6 +17,7 @@ * 0x401: for compile time BRK instruction * 0x800: kernel-mode BUG() and WARN() traps * 0x9xx: tag-based KASAN trap (allowed values 0x900 - 0x9ff) + * 0x8xxx: Control-Flow Integrity traps */ #define KPROBES_BRK_IMM 0x004 #define UPROBES_BRK_IMM 0x005 @@ -28,4 +29,9 @@ #define KASAN_BRK_IMM 0x900 #define KASAN_BRK_MASK 0x0ff +#define CFI_BRK_IMM_TARGET GENMASK(4, 0) +#define CFI_BRK_IMM_TYPE GENMASK(9, 5) +#define CFI_BRK_IMM_BASE 0x8000 +#define CFI_BRK_IMM_MASK (CFI_BRK_IMM_TARGET | CFI_BRK_IMM_TYPE) + #endif diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index dbc45a4157fa..329dbbd4d50b 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -26,7 +26,7 @@ #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS #define ARCH_SUPPORTS_FTRACE_OPS 1 #else -#define MCOUNT_ADDR ((unsigned long)function_nocfi(_mcount)) +#define MCOUNT_ADDR ((unsigned long)_mcount) #endif /* The BL at the callsite's adjusted rec->ip */ diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h index 43f8c25b3fda..1436fa1cde24 100644 --- a/arch/arm64/include/asm/linkage.h +++ b/arch/arm64/include/asm/linkage.h @@ -39,4 +39,8 @@ SYM_START(name, SYM_L_WEAK, SYM_A_NONE) \ bti c ; +#define SYM_TYPED_FUNC_START(name) \ + SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \ + bti c ; + #endif diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index c7ccd82db1d2..d3f8b5df0c1f 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -147,7 +147,7 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz) * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD, * avoiding the possibility of conflicting TLB entries being allocated. */ -static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap) +static inline void cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap) { typedef void (ttbr_replace_func)(phys_addr_t); extern ttbr_replace_func idmap_cpu_replace_ttbr1; @@ -168,7 +168,7 @@ static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp, pgd_t *idmap) ttbr1 |= TTBR_CNP_BIT; } - replace_phys = (void *)__pa_symbol(function_nocfi(idmap_cpu_replace_ttbr1)); + replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1); __cpu_install_idmap(idmap); replace_phys(ttbr1); diff --git a/arch/arm64/kernel/acpi_parking_protocol.c b/arch/arm64/kernel/acpi_parking_protocol.c index bfeeb5319abf..b1990e38aed0 100644 --- a/arch/arm64/kernel/acpi_parking_protocol.c +++ b/arch/arm64/kernel/acpi_parking_protocol.c @@ -99,7 +99,7 @@ static int acpi_parking_protocol_cpu_boot(unsigned int cpu) * that read this address need to convert this address to the * Boot-Loader's endianness before jumping. */ - writeq_relaxed(__pa_symbol(function_nocfi(secondary_entry)), + writeq_relaxed(__pa_symbol(secondary_entry), &mailbox->entry_point); writel_relaxed(cpu_entry->gic_cpu_id, &mailbox->cpu_id); diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c index 9bcaa5eacf16..d2c66507398d 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -133,7 +133,7 @@ static void clean_dcache_range_nopatch(u64 start, u64 end) } while (cur += d_size, cur < end); } -static void __nocfi __apply_alternatives(struct alt_region *region, bool is_module, +static void __apply_alternatives(struct alt_region *region, bool is_module, unsigned long *feature_mask) { struct alt_instr *alt; diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S index 48a8af97faa9..6b752fe89745 100644 --- a/arch/arm64/kernel/cpu-reset.S +++ b/arch/arm64/kernel/cpu-reset.S @@ -8,6 +8,7 @@ */ #include <linux/linkage.h> +#include <linux/cfi_types.h> #include <asm/assembler.h> #include <asm/sysreg.h> #include <asm/virt.h> @@ -28,7 +29,7 @@ * branch to what would be the reset vector. It must be executed with the * flat identity mapping. */ -SYM_CODE_START(cpu_soft_restart) +SYM_TYPED_FUNC_START(cpu_soft_restart) mov_q x12, INIT_SCTLR_EL1_MMU_OFF pre_disable_mmu_workaround /* @@ -47,6 +48,6 @@ SYM_CODE_START(cpu_soft_restart) mov x1, x3 // arg1 mov x2, x4 // arg2 br x8 -SYM_CODE_END(cpu_soft_restart) +SYM_FUNC_END(cpu_soft_restart) .popsection diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index af4de817d712..d8361691efeb 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1685,7 +1685,7 @@ static phys_addr_t kpti_ng_pgd_alloc(int shift) return kpti_ng_temp_alloc; } -static void __nocfi +static void kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) { typedef void (kpti_remap_fn)(int, int, phys_addr_t, unsigned long); @@ -1713,7 +1713,7 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused) if (arm64_use_ng_mappings) return; - remap_fn = (void *)__pa_symbol(function_nocfi(idmap_kpti_install_ng_mappings)); + remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings); if (!cpu) { alloc = __get_free_pages(GFP_ATOMIC | __GFP_ZERO, order); diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index ea5dc7c90f46..26789865748c 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -56,7 +56,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func) unsigned long pc; u32 new; - pc = (unsigned long)function_nocfi(ftrace_call); + pc = (unsigned long)ftrace_call; new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func, AARCH64_INSN_BRANCH_LINK); diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c index 19c2d487cb08..ce3d40120f72 100644 --- a/arch/arm64/kernel/machine_kexec.c +++ b/arch/arm64/kernel/machine_kexec.c @@ -204,7 +204,7 @@ void machine_kexec(struct kimage *kimage) typeof(cpu_soft_restart) *restart; cpu_install_idmap(); - restart = (void *)__pa_symbol(function_nocfi(cpu_soft_restart)); + restart = (void *)__pa_symbol(cpu_soft_restart); restart(is_hyp_nvhe(), kimage->start, kimage->arch.dtb_mem, 0, 0); } else { diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index ab7f4c476104..29a8e444db83 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -38,7 +38,7 @@ static int __init cpu_psci_cpu_prepare(unsigned int cpu) static int cpu_psci_cpu_boot(unsigned int cpu) { - phys_addr_t pa_secondary_entry = __pa_symbol(function_nocfi(secondary_entry)); + phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry); int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry); if (err) pr_err("failed to boot CPU%d (%d)\n", cpu, err); diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c index 7e1624ecab3c..49029eace3ad 100644 --- a/arch/arm64/kernel/smp_spin_table.c +++ b/arch/arm64/kernel/smp_spin_table.c @@ -66,7 +66,7 @@ static int smp_spin_table_cpu_init(unsigned int cpu) static int smp_spin_table_cpu_prepare(unsigned int cpu) { __le64 __iomem *release_addr; - phys_addr_t pa_holding_pen = __pa_symbol(function_nocfi(secondary_holding_pen)); + phys_addr_t pa_holding_pen = __pa_symbol(secondary_holding_pen); if (!cpu_release_addr[cpu]) return -ENODEV; diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index b7fed33981f7..3c026da95bbc 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -26,6 +26,7 @@ #include <linux/syscalls.h> #include <linux/mm_types.h> #include <linux/kasan.h> +#include <linux/cfi.h> #include <asm/atomic.h> #include <asm/bug.h> @@ -991,6 +992,38 @@ static struct break_hook bug_break_hook = { .imm = BUG_BRK_IMM, }; +#ifdef CONFIG_CFI_CLANG +static int cfi_handler(struct pt_regs *regs, unsigned long esr) +{ + unsigned long target; + u32 type; + + target = pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TARGET, esr)); + type = (u32)pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TYPE, esr)); + + switch (report_cfi_failure(regs, regs->pc, &target, type)) { + case BUG_TRAP_TYPE_BUG: + die("Oops - CFI", regs, 0); + break; + + case BUG_TRAP_TYPE_WARN: + break; + + default: + return DBG_HOOK_ERROR; + } + + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); + return DBG_HOOK_HANDLED; +} + +static struct break_hook cfi_break_hook = { + .fn = cfi_handler, + .imm = CFI_BRK_IMM_BASE, + .mask = CFI_BRK_IMM_MASK, +}; +#endif /* CONFIG_CFI_CLANG */ + static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr) { pr_err("%s generated an invalid instruction at %pS!\n", @@ -1052,6 +1085,9 @@ static struct break_hook kasan_break_hook = { }; #endif + +#define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) + /* * Initial handler for AArch64 BRK exceptions * This handler only used until debug_traps_init(). @@ -1059,10 +1095,12 @@ static struct break_hook kasan_break_hook = { int __init early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs) { +#ifdef CONFIG_CFI_CLANG + if ((esr_comment(esr) & ~CFI_BRK_IMM_MASK) == CFI_BRK_IMM_BASE) + return cfi_handler(regs, esr) != DBG_HOOK_HANDLED; +#endif #ifdef CONFIG_KASAN_SW_TAGS - unsigned long comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; - - if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) + if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; #endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; @@ -1071,6 +1109,9 @@ int __init early_brk64(unsigned long addr, unsigned long esr, void __init trap_init(void) { register_kernel_break_hook(&bug_break_hook); +#ifdef CONFIG_CFI_CLANG + register_kernel_break_hook(&cfi_break_hook); +#endif register_kernel_break_hook(&fault_break_hook); #ifdef CONFIG_KASAN_SW_TAGS register_kernel_break_hook(&kasan_break_hook); diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index bafbf78fab77..619e2dc7ee14 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -40,7 +40,8 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO # kernel with CONFIG_WERROR enabled. CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) \ $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) \ - $(CC_FLAGS_LTO) -Wmissing-prototypes -Wmissing-declarations + $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) \ + -Wmissing-prototypes -Wmissing-declarations KASAN_SANITIZE := n KCSAN_SANITIZE := n UBSAN_SANITIZE := n diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 7837a69524c5..8b9f419fcad9 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -10,6 +10,7 @@ #include <linux/init.h> #include <linux/linkage.h> #include <linux/pgtable.h> +#include <linux/cfi_types.h> #include <asm/assembler.h> #include <asm/asm-offsets.h> #include <asm/asm_pointer_auth.h> @@ -185,7 +186,7 @@ SYM_FUNC_END(cpu_do_resume) * This is the low-level counterpart to cpu_replace_ttbr1, and should not be * called by anything else. It can only be executed from a TTBR0 mapping. */ -SYM_FUNC_START(idmap_cpu_replace_ttbr1) +SYM_TYPED_FUNC_START(idmap_cpu_replace_ttbr1) save_and_disable_daif flags=x2 __idmap_cpu_set_reserved_ttbr1 x1, x3 @@ -253,7 +254,7 @@ SYM_FUNC_END(idmap_cpu_replace_ttbr1) SYM_DATA(__idmap_kpti_flag, .long 1) .popsection -SYM_FUNC_START(idmap_kpti_install_ng_mappings) +SYM_TYPED_FUNC_START(idmap_kpti_install_ng_mappings) cpu .req w0 temp_pte .req x0 num_cpus .req w1 diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 3ca198742b10..cabd6e13f549 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -107,6 +107,8 @@ config X86 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 + select ARCH_SUPPORTS_CFI_CLANG if X86_64 + select ARCH_USES_CFI_TRAPS if X86_64 && CFI_CLANG select ARCH_SUPPORTS_LTO_CLANG select ARCH_SUPPORTS_LTO_CLANG_THIN select ARCH_USE_BUILTIN_BSWAP diff --git a/arch/x86/crypto/blowfish-x86_64-asm_64.S b/arch/x86/crypto/blowfish-x86_64-asm_64.S index 802d71582689..4a43e072d2d1 100644 --- a/arch/x86/crypto/blowfish-x86_64-asm_64.S +++ b/arch/x86/crypto/blowfish-x86_64-asm_64.S @@ -6,6 +6,7 @@ */ #include <linux/linkage.h> +#include <linux/cfi_types.h> .file "blowfish-x86_64-asm.S" .text @@ -141,7 +142,7 @@ SYM_FUNC_START(__blowfish_enc_blk) RET; SYM_FUNC_END(__blowfish_enc_blk) -SYM_FUNC_START(blowfish_dec_blk) +SYM_TYPED_FUNC_START(blowfish_dec_blk) /* input: * %rdi: ctx * %rsi: dst @@ -332,7 +333,7 @@ SYM_FUNC_START(__blowfish_enc_blk_4way) RET; SYM_FUNC_END(__blowfish_enc_blk_4way) -SYM_FUNC_START(blowfish_dec_blk_4way) +SYM_TYPED_FUNC_START(blowfish_dec_blk_4way) /* input: * %rdi: ctx * %rsi: dst diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 12f6c4d714cd..381d3333b996 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -91,7 +91,7 @@ ifneq ($(RETPOLINE_VDSO_CFLAGS),) endif endif -$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) $(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO # @@ -153,6 +153,7 @@ KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32)) KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic KBUILD_CFLAGS_32 += -fno-stack-protector KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls) diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h new file mode 100644 index 000000000000..58dacd90daef --- /dev/null +++ b/arch/x86/include/asm/cfi.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_CFI_H +#define _ASM_X86_CFI_H + +/* + * Clang Control Flow Integrity (CFI) support. + * + * Copyright (C) 2022 Google LLC + */ + +#include <linux/cfi.h> + +#ifdef CONFIG_CFI_CLANG +enum bug_trap_type handle_cfi_failure(struct pt_regs *regs); +#else +static inline enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) +{ + return BUG_TRAP_TYPE_NONE; +} +#endif /* CONFIG_CFI_CLANG */ + +#endif /* _ASM_X86_CFI_H */ diff --git a/arch/x86/include/asm/linkage.h b/arch/x86/include/asm/linkage.h index 73ca20049835..f484d656d34e 100644 --- a/arch/x86/include/asm/linkage.h +++ b/arch/x86/include/asm/linkage.h @@ -43,6 +43,18 @@ #endif /* __ASSEMBLY__ */ +#define __CFI_TYPE(name) \ + SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE) \ + .fill 11, 1, 0x90 ASM_NL \ + .byte 0xb8 ASM_NL \ + .long __kcfi_typeid_##name ASM_NL \ + SYM_FUNC_END(__cfi_##name) + +/* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */ +#define SYM_TYPED_FUNC_START(name) \ + SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \ + ENDBR + /* SYM_FUNC_START -- use for global functions */ #define SYM_FUNC_START(name) \ SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN) \ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index a20a5ebfacd7..1286a73ebdbc 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -139,6 +139,8 @@ obj-$(CONFIG_UNWINDER_GUESS) += unwind_guess.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += sev.o +obj-$(CONFIG_CFI_CLANG) += cfi.o + ### # 64 bit specific files ifeq ($(CONFIG_X86_64),y) diff --git a/arch/x86/kernel/cfi.c b/arch/x86/kernel/cfi.c new file mode 100644 index 000000000000..8674a5c0c031 --- /dev/null +++ b/arch/x86/kernel/cfi.c @@ -0,0 +1,86 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Clang Control Flow Integrity (CFI) support. + * + * Copyright (C) 2022 Google LLC + */ +#include <asm/cfi.h> +#include <asm/insn.h> +#include <asm/insn-eval.h> +#include <linux/string.h> + +/* + * Returns the target address and the expected type when regs->ip points + * to a compiler-generated CFI trap. + */ +static bool decode_cfi_insn(struct pt_regs *regs, unsigned long *target, + u32 *type) +{ + char buffer[MAX_INSN_SIZE]; + struct insn insn; + int offset = 0; + + *target = *type = 0; + + /* + * The compiler generates the following instruction sequence + * for indirect call checks: + * + * movl -<id>, %r10d ; 6 bytes + * addl -4(%reg), %r10d ; 4 bytes + * je .Ltmp1 ; 2 bytes + * ud2 ; <- regs->ip + * .Ltmp1: + * + * We can decode the expected type and the target address from the + * movl/addl instructions. + */ + if (copy_from_kernel_nofault(buffer, (void *)regs->ip - 12, MAX_INSN_SIZE)) + return false; + if (insn_decode_kernel(&insn, &buffer[offset])) + return false; + if (insn.opcode.value != 0xBA) + return false; + + *type = -(u32)insn.immediate.value; + + if (copy_from_kernel_nofault(buffer, (void *)regs->ip - 6, MAX_INSN_SIZE)) + return false; + if (insn_decode_kernel(&insn, &buffer[offset])) + return false; + if (insn.opcode.value != 0x3) + return false; + + /* Read the target address from the register. */ + offset = insn_get_modrm_rm_off(&insn, regs); + if (offset < 0) + return false; + + *target = *(unsigned long *)((void *)regs + offset); + + return true; +} + +/* + * Checks if a ud2 trap is because of a CFI failure, and handles the trap + * if needed. Returns a bug_trap_type value similarly to report_bug. + */ +enum bug_trap_type handle_cfi_failure(struct pt_regs *regs) +{ + unsigned long target; + u32 type; + + if (!is_cfi_trap(regs->ip)) + return BUG_TRAP_TYPE_NONE; + + if (!decode_cfi_insn(regs, &target, &type)) + return report_cfi_failure_noaddr(regs, regs->ip); + + return report_cfi_failure(regs, regs->ip, &target, type); +} + +/* + * Ensure that __kcfi_typeid_ symbols are emitted for functions that may + * not be indirectly called with all configurations. + */ +__ADDRESSABLE(__memcpy) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index d62b2cb85cea..178015a820f0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -63,6 +63,7 @@ #include <asm/insn-eval.h> #include <asm/vdso.h> #include <asm/tdx.h> +#include <asm/cfi.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -313,7 +314,8 @@ static noinstr bool handle_bug(struct pt_regs *regs) */ if (regs->flags & X86_EFLAGS_IF) raw_local_irq_enable(); - if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) { + if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN || + handle_cfi_failure(regs) == BUG_TRAP_TYPE_WARN) { regs->ip += LEN_UD2; handled = true; } diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S index d0d7b9bc6cad..dd8cd8831251 100644 --- a/arch/x86/lib/memcpy_64.S +++ b/arch/x86/lib/memcpy_64.S @@ -2,6 +2,7 @@ /* Copyright 2002 Andi Kleen */ #include <linux/linkage.h> +#include <linux/cfi_types.h> #include <asm/errno.h> #include <asm/cpufeatures.h> #include <asm/alternative.h> @@ -27,7 +28,7 @@ * Output: * rax original destination */ -SYM_FUNC_START(__memcpy) +SYM_TYPED_FUNC_START(__memcpy) ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ "jmp memcpy_erms", X86_FEATURE_ERMS diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index 31c634a22818..58a200dc762d 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -55,6 +55,10 @@ ifdef CONFIG_RETPOLINE PURGATORY_CFLAGS_REMOVE += $(RETPOLINE_CFLAGS) endif +ifdef CONFIG_CFI_CLANG +PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_CFI) +endif + CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE) CFLAGS_purgatory.o += $(PURGATORY_CFLAGS) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index e2c5b296120d..2925074b9a58 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -56,6 +56,7 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = { "^(xen_irq_disable_direct_reloc$|" "xen_save_fl_direct_reloc$|" "VDSO|" + "__kcfi_typeid_|" "__crc_)", /* |