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Message-Id: <20170810172615.51965-20-thgarnie@google.com>
Date: Thu, 10 Aug 2017 10:26:11 -0700
From: Thomas Garnier <thgarnie@...gle.com>
To: Herbert Xu <herbert@...dor.apana.org.au>,
"David S . Miller" <davem@...emloft.net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Arnd Bergmann <arnd@...db.de>,
Thomas Garnier <thgarnie@...gle.com>,
Matthias Kaehlcke <mka@...omium.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Joerg Roedel <joro@...tes.org>,
Tom Lendacky <thomas.lendacky@....com>,
Andy Lutomirski <luto@...nel.org>,
Borislav Petkov <bp@...e.de>,
Brian Gerst <brgerst@...il.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Len Brown <len.brown@...el.com>,
Pavel Machek <pavel@....cz>,
Tejun Heo <tj@...nel.org>,
Christoph Lameter <cl@...ux.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Chris Metcalf <cmetcalf@...lanox.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>,
Nicolas Pitre <nicolas.pitre@...aro.org>,
Christopher Li <sparse@...isli.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
Lukas Wunner <lukas@...ner.de>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Dou Liyang <douly.fnst@...fujitsu.com>,
Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
Masahiro Yamada <yamada.masahiro@...ionext.com>,
Markus Trippelsdorf <markus@...ppelsdorf.de>,
Steven Rostedt <rostedt@...dmis.org>,
Kees Cook <keescook@...omium.org>,
Rik van Riel <riel@...hat.com>,
David Howells <dhowells@...hat.com>,
Waiman Long <longman@...hat.com>,
Kyle Huey <me@...ehuey.com>,
Peter Foley <pefoley2@...oley.com>,
Tim Chen <tim.c.chen@...ux.intel.com>,
Catalin Marinas <catalin.marinas@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Michal Hocko <mhocko@...e.com>,
Matthew Wilcox <mawilcox@...rosoft.com>,
"H . J . Lu" <hjl.tools@...il.com>,
Paul Bolle <pebolle@...cali.nl>,
Rob Landley <rob@...dley.net>,
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Daniel Micay <danielmicay@...il.com>
Cc: x86@...nel.org,
linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org,
xen-devel@...ts.xenproject.org,
kvm@...r.kernel.org,
linux-pm@...r.kernel.org,
linux-arch@...r.kernel.org,
linux-sparse@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: [RFC v2 19/23] x86: Support global stack cookie
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 going to be
fixed with a compiler change allowing to pick the segment register as
done on PowerPC. In the meantime, this configuration can be used to
support older compilers.
Signed-off-by: Thomas Garnier <thgarnie@...gle.com>
---
arch/x86/Kconfig | 4 ++++
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, 48 insertions(+), 13 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index da37ba375e63..2632fa8e8945 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2128,6 +2128,10 @@ config RANDOMIZE_MEMORY_PHYSICAL_PADDING
If unsure, leave at the default value.
+config X86_GLOBAL_STACKPROTECTOR
+ bool
+ depends on CC_STACKPROTECTOR
+
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs"
depends on SMP
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 1e902f926be3..66af2704f096 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -58,6 +58,15 @@ endif
KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow
KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
+ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR
+ ifeq ($(call cc-option, -mstack-protector-guard=global),)
+ $(error Cannot use CONFIG_X86_GLOBAL_STACKPROTECTOR: \
+ -mstack-protector-guard=global not supported \
+ by compiler)
+ endif
+ KBUILD_CFLAGS += -mstack-protector-guard=global
+endif
+
ifeq ($(CONFIG_X86_32),y)
BITS := 32
UTS_MACHINE := i386
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 48ef7bb32c42..91b4f2c4f837 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -237,7 +237,8 @@ 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 c1f9b29d4c24..566380112a4f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -395,7 +395,8 @@ 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 14fc21e2df08..842b3b5d5e36 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -394,7 +394,8 @@ DECLARE_PER_CPU(char *, irq_stack_ptr);
DECLARE_PER_CPU(unsigned int, irq_count);
extern asmlinkage void ignore_sysret(void);
#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 8abedf1d650e..66462d778dc5 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -51,6 +51,10 @@
#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.
*
@@ -62,7 +66,7 @@ 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
/*
@@ -76,17 +80,22 @@ 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;
@@ -99,7 +108,7 @@ 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
}
@@ -115,7 +124,7 @@ 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 de827d6ac8c2..b30a12cd021e 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -30,7 +30,8 @@
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 880aa093268d..9deb60866eab 100644
--- a/arch/x86/kernel/asm-offsets_32.c
+++ b/arch/x86/kernel/asm-offsets_32.c
@@ -57,7 +57,8 @@ void foo(void)
/* Size of SYSENTER_stack */
DEFINE(SIZEOF_SYSENTER_stack, sizeof(((struct tss_struct *)0)->SYSENTER_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 99332f550c48..297bcdfc520a 100644
--- a/arch/x86/kernel/asm-offsets_64.c
+++ b/arch/x86/kernel/asm-offsets_64.c
@@ -65,7 +65,8 @@ int main(void)
OFFSET(TSS_sp0, tss_struct, x86_tss.sp0);
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 31300767ec0f..9e8608fc10a4 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1454,7 +1454,8 @@ 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 0332664eb158..6989bfb0a628 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -411,7 +411,8 @@ setup_once:
addl $8,%edi
loop 2b
-#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 bd6b85fac666..66ea1a35413e 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -73,6 +73,11 @@ EXPORT_PER_CPU_SYMBOL(cpu_tss);
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.
--
2.14.0.434.g98096fd7a8-goog
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