From patchwork Thu Oct 24 22:51:32 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sami Tolvanen X-Patchwork-Id: 11211869 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9DD011390 for ; Fri, 25 Oct 2019 09:30:03 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 9386621D82 for ; Fri, 25 Oct 2019 09:30:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hAhjVTL6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9386621D82 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17122-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 9729 invoked by uid 550); 25 Oct 2019 09:28:24 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 19909 invoked from network); 24 Oct 2019 22:52:49 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=laHam8Bnh9szHwPpPFYZjoC0jp7B6WsVFsvms1hxAEc=; b=hAhjVTL6bIoJcrYQCYE63DErpy264AwpcxfLVA7FIoiOcz0cS/jQb/1jcof/bmmE7A qXq6jBR/bFCJtzydIP5jPHxSqHzVe5FoHlfxgDrRsZBoYNIbHeXTMtPUVOykUx8q6Ghj SOcwCH6Ku0YvNmNaUpfWHcew2ngAI4NrWsZzCPK53NAHQ/8OCc3unlu3OWeCmklO4pS0 6i4iZLs97kLpN4QTkOCRYxYVSimdUqechOywcPctiGqOVcld/EtiGRsQXCCo0he7QW/e XppoFtcrNDViO4QNhpHnFHEh2dPgNlThf4io5XsbDFAhoRMYkpckaAf+6zMC1BpYxg11 csOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=laHam8Bnh9szHwPpPFYZjoC0jp7B6WsVFsvms1hxAEc=; b=n1wsl6otVrdgPLFQK76UVgO15OV7P+0i83hzbQFeelYIh/GtuJ9noH6iBC94ofdXci JVVDqTg0NzBAiMVqIupNKnF02n5oIwVVf4jzWA0OtlJNKSfHiBhY6t2zKITuz2QTsSq0 XvzQ+PzDETHbtrciRezaBzGX0NEfuaKjr++JF3OCfZMRxYyKv5dk/0hWRKXKcc8ocDoz kr93HtMNRMe7DVyW5JzSmy343JDeEyl0nTeJ+QwYiQMp1cLLPTf2W9ZvungzwxdVFnJ8 xfdA9f60HKavrHmZbVyJ2q5LVY4xl/uI9DQNIDF5Kd/FPjMmJBm5znThqIJrYFeUj3lM lYJg== X-Gm-Message-State: APjAAAXqfga8Ujlq2BpjWPf3q49X9lbMNribkreQBFuS83uB+gbDTKHi S7Gp7+TtJG2XjNHGcW5FNmAfs0quErGa8WdAS1g= X-Google-Smtp-Source: APXvYqyUhFN230tJ8s/TZZIgZ3a08ItgOwIEn1bSB4vjFzKb3iaXQa+ZkHrZ+sdPxXk52O8lZ7SQkyVhX6Q+uI737Go= X-Received: by 2002:a65:6203:: with SMTP id d3mr515180pgv.272.1571957557198; Thu, 24 Oct 2019 15:52:37 -0700 (PDT) Date: Thu, 24 Oct 2019 15:51:32 -0700 In-Reply-To: <20191024225132.13410-1-samitolvanen@google.com> Message-Id: <20191024225132.13410-18-samitolvanen@google.com> Mime-Version: 1.0 References: <20191018161033.261971-1-samitolvanen@google.com> <20191024225132.13410-1-samitolvanen@google.com> X-Mailer: git-send-email 2.24.0.rc0.303.g954a862665-goog Subject: [PATCH v2 17/17] arm64: implement Shadow Call Stack From: samitolvanen@google.com To: Will Deacon , Catalin Marinas , Steven Rostedt , Masami Hiramatsu , Ard Biesheuvel Cc: Dave Martin , Kees Cook , Laura Abbott , Mark Rutland , Nick Desaulniers , Jann Horn , Miguel Ojeda , Masahiro Yamada , clang-built-linux@googlegroups.com, kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Sami Tolvanen This change implements shadow stack switching, initial SCS set-up, and interrupt shadow stacks for arm64. Signed-off-by: Sami Tolvanen --- arch/arm64/Kconfig | 5 ++++ arch/arm64/include/asm/scs.h | 45 ++++++++++++++++++++++++++++ arch/arm64/include/asm/stacktrace.h | 4 +++ arch/arm64/include/asm/thread_info.h | 3 ++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/asm-offsets.c | 3 ++ arch/arm64/kernel/entry.S | 28 +++++++++++++++++ arch/arm64/kernel/head.S | 9 ++++++ arch/arm64/kernel/irq.c | 2 ++ arch/arm64/kernel/process.c | 2 ++ arch/arm64/kernel/scs.c | 39 ++++++++++++++++++++++++ arch/arm64/kernel/smp.c | 4 +++ 12 files changed, 145 insertions(+) create mode 100644 arch/arm64/include/asm/scs.h create mode 100644 arch/arm64/kernel/scs.c diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 42867174920f..f4c94c5e8012 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -66,6 +66,7 @@ config ARM64 select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS select ARCH_SUPPORTS_MEMORY_FAILURE + select ARCH_SUPPORTS_SHADOW_CALL_STACK if CC_HAVE_SHADOW_CALL_STACK select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 50000 || CC_IS_CLANG select ARCH_SUPPORTS_NUMA_BALANCING @@ -948,6 +949,10 @@ config ARCH_HAS_CACHE_LINE_SIZE config ARCH_ENABLE_SPLIT_PMD_PTLOCK def_bool y if PGTABLE_LEVELS > 2 +# Supported by clang >= 7.0 +config CC_HAVE_SHADOW_CALL_STACK + def_bool $(cc-option, -fsanitize=shadow-call-stack -ffixed-x18) + config SECCOMP bool "Enable seccomp to safely compute untrusted bytecode" ---help--- diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h new file mode 100644 index 000000000000..76dda1228935 --- /dev/null +++ b/arch/arm64/include/asm/scs.h @@ -0,0 +1,45 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_SCS_H +#define _ASM_SCS_H + +#ifndef __ASSEMBLY__ + +#include + +#ifdef CONFIG_SHADOW_CALL_STACK + +extern void scs_init_irq(void); + +static __always_inline void scs_save(struct task_struct *tsk) +{ + void *s; + + asm volatile("mov %0, x18" : "=r" (s)); + task_set_scs(tsk, s); +} + +static inline void scs_overflow_check(struct task_struct *tsk) +{ + if (unlikely(scs_corrupted(tsk))) + panic("corrupted shadow stack detected inside scheduler\n"); +} + +#else /* CONFIG_SHADOW_CALL_STACK */ + +static inline void scs_init_irq(void) +{ +} + +static inline void scs_save(struct task_struct *tsk) +{ +} + +static inline void scs_overflow_check(struct task_struct *tsk) +{ +} + +#endif /* CONFIG_SHADOW_CALL_STACK */ + +#endif /* __ASSEMBLY __ */ + +#endif /* _ASM_SCS_H */ diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index 4d9b1f48dc39..b6cf32fb4efe 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -68,6 +68,10 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk); DECLARE_PER_CPU(unsigned long *, irq_stack_ptr); +#ifdef CONFIG_SHADOW_CALL_STACK +DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr); +#endif + static inline bool on_irq_stack(unsigned long sp, struct stack_info *info) { diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h index f0cec4160136..8c73764b9ed2 100644 --- a/arch/arm64/include/asm/thread_info.h +++ b/arch/arm64/include/asm/thread_info.h @@ -41,6 +41,9 @@ struct thread_info { #endif } preempt; }; +#ifdef CONFIG_SHADOW_CALL_STACK + void *shadow_call_stack; +#endif }; #define thread_saved_pc(tsk) \ diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 478491f07b4f..b3995329d9e5 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -63,6 +63,7 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o obj-$(CONFIG_ARM64_SSBD) += ssbd.o obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o +obj-$(CONFIG_SHADOW_CALL_STACK) += scs.o obj-y += vdso/ probes/ obj-$(CONFIG_COMPAT_VDSO) += vdso32/ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 214685760e1c..f6762b9ae1e1 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -33,6 +33,9 @@ int main(void) DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit)); #ifdef CONFIG_ARM64_SW_TTBR0_PAN DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0)); +#endif +#ifdef CONFIG_SHADOW_CALL_STACK + DEFINE(TSK_TI_SCS, offsetof(struct task_struct, thread_info.shadow_call_stack)); #endif DEFINE(TSK_STACK, offsetof(struct task_struct, stack)); #ifdef CONFIG_STACKPROTECTOR diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index cf3bd2976e57..12a5bc209280 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -172,6 +172,10 @@ alternative_cb_end apply_ssbd 1, x22, x23 +#ifdef CONFIG_SHADOW_CALL_STACK + ldr x18, [tsk, #TSK_TI_SCS] // Restore shadow call stack + str xzr, [tsk, #TSK_TI_SCS] +#endif .else add x21, sp, #S_FRAME_SIZE get_current_task tsk @@ -278,6 +282,12 @@ alternative_else_nop_endif ct_user_enter .endif +#ifdef CONFIG_SHADOW_CALL_STACK + .if \el == 0 + str x18, [tsk, #TSK_TI_SCS] // Save shadow call stack + .endif +#endif + #ifdef CONFIG_ARM64_SW_TTBR0_PAN /* * Restore access to TTBR0_EL1. If returning to EL0, no need for SPSR @@ -383,6 +393,9 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 .macro irq_stack_entry mov x19, sp // preserve the original sp +#ifdef CONFIG_SHADOW_CALL_STACK + mov x20, x18 // preserve the original shadow stack +#endif /* * Compare sp with the base of the task stack. @@ -400,6 +413,12 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 /* switch to the irq stack */ mov sp, x26 + +#ifdef CONFIG_SHADOW_CALL_STACK + /* also switch to the irq shadow stack */ + ldr_this_cpu x18, irq_shadow_call_stack_ptr, x26 +#endif + 9998: .endm @@ -409,6 +428,10 @@ alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 */ .macro irq_stack_exit mov sp, x19 +#ifdef CONFIG_SHADOW_CALL_STACK + /* x20 is also preserved */ + mov x18, x20 +#endif .endm /* GPRs used by entry code */ @@ -1155,6 +1178,11 @@ ENTRY(cpu_switch_to) ldr lr, [x8] mov sp, x9 msr sp_el0, x1 +#ifdef CONFIG_SHADOW_CALL_STACK + str x18, [x0, #TSK_TI_SCS] + ldr x18, [x1, #TSK_TI_SCS] + str xzr, [x1, #TSK_TI_SCS] +#endif ret ENDPROC(cpu_switch_to) NOKPROBE(cpu_switch_to) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 989b1944cb71..2be977c6496f 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -424,6 +425,10 @@ __primary_switched: stp xzr, x30, [sp, #-16]! mov x29, sp +#ifdef CONFIG_SHADOW_CALL_STACK + adr_l x18, init_shadow_call_stack // Set shadow call stack +#endif + str_l x21, __fdt_pointer, x5 // Save FDT pointer ldr_l x4, kimage_vaddr // Save the offset between @@ -731,6 +736,10 @@ __secondary_switched: ldr x2, [x0, #CPU_BOOT_TASK] cbz x2, __secondary_too_slow msr sp_el0, x2 +#ifdef CONFIG_SHADOW_CALL_STACK + ldr x18, [x2, #TSK_TI_SCS] // Set shadow call stack + str xzr, [x2, #TSK_TI_SCS] +#endif mov x29, #0 mov x30, #0 b secondary_start_kernel diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index 04a327ccf84d..fe0ca522ff60 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -21,6 +21,7 @@ #include #include #include +#include unsigned long irq_err_count; @@ -63,6 +64,7 @@ static void init_irq_stacks(void) void __init init_IRQ(void) { init_irq_stacks(); + scs_init_irq(); irqchip_init(); if (!handle_arch_irq) panic("No interrupt controller found."); diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 71f788cd2b18..5f0aec285848 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -52,6 +52,7 @@ #include #include #include +#include #include #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) @@ -507,6 +508,7 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, uao_thread_switch(next); ptrauth_thread_switch(next); ssbs_thread_switch(next); + scs_overflow_check(next); /* * Complete any pending TLB or cache maintenance on this CPU in case diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c new file mode 100644 index 000000000000..6f255072c9a9 --- /dev/null +++ b/arch/arm64/kernel/scs.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Shadow Call Stack support. + * + * Copyright (C) 2019 Google LLC + */ + +#include +#include +#include + +DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr); + +#ifndef CONFIG_SHADOW_CALL_STACK_VMAP +DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], irq_shadow_call_stack) + __aligned(SCS_SIZE); +#endif + +void scs_init_irq(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { +#ifdef CONFIG_SHADOW_CALL_STACK_VMAP + unsigned long *p; + + p = __vmalloc_node_range(SCS_SIZE, SCS_SIZE, + VMALLOC_START, VMALLOC_END, + SCS_GFP, PAGE_KERNEL, + 0, cpu_to_node(cpu), + __builtin_return_address(0)); + + per_cpu(irq_shadow_call_stack_ptr, cpu) = p; +#else + per_cpu(irq_shadow_call_stack_ptr, cpu) = + per_cpu(irq_shadow_call_stack, cpu); +#endif /* CONFIG_SHADOW_CALL_STACK_VMAP */ + } +} diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index dc9fe879c279..cc1938a585d2 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -44,6 +44,7 @@ #include #include #include +#include #include #include #include @@ -357,6 +358,9 @@ void cpu_die(void) { unsigned int cpu = smp_processor_id(); + /* Save the shadow stack pointer before exiting the idle task */ + scs_save(current); + idle_task_exit(); local_daif_mask();