From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Garnier via Virtualization Subject: [PATCH v3 20/27] x86: Support global stack cookie Date: Wed, 23 May 2018 12:54:14 -0700 Message-ID: <20180523195421.180248-21-thgarnie__4568.59957562319$1527106369$gmane$org@google.com> References: <20180523195421.180248-1-thgarnie@google.com> Reply-To: Thomas Garnier Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180523195421.180248-1-thgarnie@google.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Herbert Xu , "David S . Miller" , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Peter Zijlstra , Josh Poimboeuf , Greg Kroah-Hartman , Thomas Garnier , Philippe Ombredanne , Kate Stewart , Arnaldo Carvalho de Melo , Yonghong Song , Andrey Ryabinin , Kees Cook , Tom Lendacky , "Kirill A . Shutemov" , Andy Lutomirski , Dominik Brodowski , Borislav Petkov , Borislav Petkov , "Rafael J . Wysocki" Len Cc: linux-arch@vger.kernel.org, kvm@vger.kernel.org, linux-pm@vger.kernel.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-sparse@vger.kernel.org, linux-crypto@vger.kernel.org, kernel-hardening@lists.openwall.com, xen-devel@lists.xenproject.org List-Id: virtualization@lists.linuxfoundation.org Add an off-by-default configuration option to use a global stack cookie instead of the default TLS. This configuration option will only be used with PIE binaries. For kernel stack cookie, the compiler uses the mcmodel=kernel to switch between the fs segment to gs segment. A PIE binary does not use mcmodel=kernel because it can be relocated anywhere, therefore the compiler will default to the fs segment register. This is fixed on the latest version of gcc. If the segment selector is available, it will be automatically added. If the automatic configuration was selected, a warning is written and the global variable stack cookie is used. If a specific stack mode was selected (regular or strong) and the compiler does not support selecting the segment register, an error is emitted. Signed-off-by: Thomas Garnier --- arch/x86/Kconfig | 12 ++++++++++++ arch/x86/Makefile | 9 +++++++++ arch/x86/entry/entry_32.S | 3 ++- arch/x86/entry/entry_64.S | 3 ++- arch/x86/include/asm/processor.h | 3 ++- arch/x86/include/asm/stackprotector.h | 19 ++++++++++++++----- 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 | 3 ++- arch/x86/kernel/head_32.S | 3 ++- arch/x86/kernel/process.c | 5 +++++ 12 files changed, 56 insertions(+), 13 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index dda87a331a7e..0fc2e981458d 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2199,6 +2199,18 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING If unsure, leave at the default value. +config X86_GLOBAL_STACKPROTECTOR + bool "Stack cookie using a global variable" + depends on CC_STACKPROTECTOR_AUTO + default n + ---help--- + This option turns on the "stack-protector" GCC feature using a global + variable instead of a segment register. It is useful when the + compiler does not support custom segment registers when building a + position independent (PIE) binary. + + If unsure, say N + config HOTPLUG_CPU bool "Support for hot-pluggable CPUs" depends on SMP diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 60135cbd905c..277ffc57ae13 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -141,6 +141,15 @@ else KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time) endif +ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR + ifeq ($(call cc-option, -mstack-protector-guard=global),) + $(error Cannot use CONFIG_X86_GLOBAL_STACKPROTECTOR: \ + -mstack-protector-guard=global not supported \ + by compiler) + endif + KBUILD_CFLAGS += -mstack-protector-guard=global +endif + ifdef CONFIG_X86_X32 x32_ld_ok := $(call try-run,\ /bin/echo -e '1: .quad 1b' | \ diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index bb4f540be234..2f9bdbc6be6d 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -241,7 +241,8 @@ ENTRY(__switch_to_asm) movl %esp, TASK_threadsp(%eax) movl TASK_threadsp(%edx), %esp -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) movl TASK_stack_canary(%edx), %ebx movl %ebx, PER_CPU_VAR(stack_canary)+stack_canary_offset #endif diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index c1700b00b1b6..c8b4e8a7d1e1 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -359,7 +359,8 @@ ENTRY(__switch_to_asm) movq %rsp, TASK_threadsp(%rdi) movq TASK_threadsp(%rsi), %rsp -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) movq TASK_stack_canary(%rsi), %rbx movq %rbx, PER_CPU_VAR(irq_stack_union + stack_canary_offset) #endif diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 5cf36fa30254..6e5d9ac3bf17 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -414,7 +414,8 @@ extern asmlinkage void ignore_sysret(void); void save_fsgs_for_kvm(void); #endif #else /* X86_64 */ -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) /* * Make sure stack canary segment base is cached-aligned: * "For Intel Atom processors, avoid non zero segment base address diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h index 371b3a4af000..5063f57d99f5 100644 --- a/arch/x86/include/asm/stackprotector.h +++ b/arch/x86/include/asm/stackprotector.h @@ -52,6 +52,10 @@ #define GDT_STACK_CANARY_INIT \ [GDT_ENTRY_STACK_CANARY] = GDT_ENTRY_INIT(0x4090, 0, 0x18), +#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR +extern unsigned long __stack_chk_guard; +#endif + /* * Initialize the stackprotector canary value. * @@ -63,7 +67,7 @@ static __always_inline void boot_init_stack_canary(void) u64 canary; u64 tsc; -#ifdef CONFIG_X86_64 +#if defined(CONFIG_X86_64) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40); #endif /* @@ -77,17 +81,22 @@ static __always_inline void boot_init_stack_canary(void) canary += tsc + (tsc << 32UL); canary &= CANARY_MASK; +#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR + if (__stack_chk_guard == 0) + __stack_chk_guard = canary ?: 1; +#else /* !CONFIG_X86_GLOBAL_STACKPROTECTOR */ current->stack_canary = canary; #ifdef CONFIG_X86_64 this_cpu_write(irq_stack_union.stack_canary, canary); -#else +#else /* CONFIG_X86_32 */ this_cpu_write(stack_canary.canary, canary); #endif +#endif } static inline void setup_stack_canary_segment(int cpu) { -#ifdef CONFIG_X86_32 +#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) unsigned long canary = (unsigned long)&per_cpu(stack_canary, cpu); struct desc_struct *gdt_table = get_cpu_gdt_rw(cpu); struct desc_struct desc; @@ -100,7 +109,7 @@ static inline void setup_stack_canary_segment(int cpu) static inline void load_stack_canary_segment(void) { -#ifdef CONFIG_X86_32 +#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) asm("mov %0, %%gs" : : "r" (__KERNEL_STACK_CANARY) : "memory"); #endif } @@ -116,7 +125,7 @@ static inline void setup_stack_canary_segment(int cpu) static inline void load_stack_canary_segment(void) { -#ifdef CONFIG_X86_32 +#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) asm volatile ("mov %0, %%gs" : : "r" (0)); #endif } diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 76417a9aab73..4c9e1b667bda 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -32,7 +32,8 @@ void common(void) { BLANK(); OFFSET(TASK_threadsp, task_struct, thread.sp); -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) OFFSET(TASK_stack_canary, task_struct, stack_canary); #endif diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index f91ba53e06c8..cf8ef55a8b82 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -50,7 +50,8 @@ void foo(void) DEFINE(TSS_sysenter_sp0, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) - offsetofend(struct cpu_entry_area, entry_stack_page.stack)); -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) BLANK(); OFFSET(stack_canary_offset, stack_canary, canary); #endif diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index bf51e51d808d..a3c7e14f6434 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -69,7 +69,8 @@ int main(void) OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); BLANK(); -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) DEFINE(stack_canary_offset, offsetof(union irq_stack_union, stack_canary)); BLANK(); #endif diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 39ed2e6ff8a0..d279a7df5018 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1540,7 +1540,8 @@ DEFINE_PER_CPU(unsigned long, cpu_current_top_of_stack) = (unsigned long)&init_thread_union + THREAD_SIZE; EXPORT_PER_CPU_SYMBOL(cpu_current_top_of_stack); -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) DEFINE_PER_CPU_ALIGNED(struct stack_canary, stack_canary); #endif diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index b59e4fb40fd9..0e849242de91 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -375,7 +375,8 @@ ENDPROC(startup_32_smp) */ __INIT setup_once: -#ifdef CONFIG_CC_STACKPROTECTOR +#if defined(CONFIG_CC_STACKPROTECTOR) && \ + !defined(CONFIG_X86_GLOBAL_STACKPROTECTOR) /* * Configure the stack canary. The linker can't handle this by * relocation. Manually set base address in stack canary diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 03408b942adb..ebe21d258a82 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -86,6 +86,11 @@ EXPORT_PER_CPU_SYMBOL(cpu_tss_rw); DEFINE_PER_CPU(bool, __tss_limit_invalid); EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid); +#ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR +unsigned long __stack_chk_guard __read_mostly; +EXPORT_SYMBOL(__stack_chk_guard); +#endif + /* * this gets called so that we can store lazy state into memory and copy the * current task into the new thread. -- 2.17.0.441.gb46fe60e1d-goog