* [PATCH v2 2/2] riscv: Enable per-task stack canaries
2020-07-09 7:28 [PATCH v2 1/2] riscv: Add STACKPROTECTOR supported guoren
@ 2020-07-09 7:28 ` guoren
2020-07-09 18:36 ` [PATCH v2 1/2] riscv: Add STACKPROTECTOR supported kernel test robot
1 sibling, 0 replies; 4+ messages in thread
From: guoren @ 2020-07-09 7:28 UTC (permalink / raw)
To: palmerdabbelt, paul.walmsley, anup, greentime.hu, zong.li, me,
bjorn.topel, atish.patra
Cc: linux-riscv, linux-kernel, linux-csky, guoren, Guo Ren, cooper,
Kees Cook
From: Guo Ren <guoren@linux.alibaba.com>
This enables the use of per-task stack canary values if GCC has
support for emitting the stack canary reference relative to the
value of tp, which holds the task struct pointer in the riscv
kernel.
After compare arm64 and x86 implementations, seems arm64's is more
flexible and readable. The key point is how gcc get the offset of
stack_canary from gs/el0_sp.
x86: Use a fix offset from gs, not flexible.
struct fixed_percpu_data {
/*
* GCC hardcodes the stack canary as %gs:40. Since the
* irq_stack is the object at %gs:0, we reserve the bottom
* 48 bytes of the irq stack for the canary.
*/
char gs_base[40]; // :(
unsigned long stack_canary;
};
arm64: Use -mstack-protector-guard-offset & guard-reg
gcc options:
-mstack-protector-guard=sysreg
-mstack-protector-guard-reg=sp_el0
-mstack-protector-guard-offset=xxx
riscv: Use -mstack-protector-guard-offset & guard-reg
gcc options:
-mstack-protector-guard=tls
-mstack-protector-guard-reg=tp
-mstack-protector-guard-offset=xxx
Here is riscv gcc's work [1].
[1] https://gcc.gnu.org/pipermail/gcc-patches/2020-July/549583.html
In the end, these codes are inserted by gcc before return:
* 0xffffffe00020b396 <+120>: ld a5,1008(tp) # 0x3f0
* 0xffffffe00020b39a <+124>: xor a5,a5,a4
* 0xffffffe00020b39c <+126>: mv a0,s5
* 0xffffffe00020b39e <+128>: bnez a5,0xffffffe00020b61c <_do_fork+766>
0xffffffe00020b3a2 <+132>: ld ra,136(sp)
0xffffffe00020b3a4 <+134>: ld s0,128(sp)
0xffffffe00020b3a6 <+136>: ld s1,120(sp)
0xffffffe00020b3a8 <+138>: ld s2,112(sp)
0xffffffe00020b3aa <+140>: ld s3,104(sp)
0xffffffe00020b3ac <+142>: ld s4,96(sp)
0xffffffe00020b3ae <+144>: ld s5,88(sp)
0xffffffe00020b3b0 <+146>: ld s6,80(sp)
0xffffffe00020b3b2 <+148>: ld s7,72(sp)
0xffffffe00020b3b4 <+150>: addi sp,sp,144
0xffffffe00020b3b6 <+152>: ret
...
* 0xffffffe00020b61c <+766>: auipc ra,0x7f8
* 0xffffffe00020b620 <+770>: jalr -1764(ra) # 0xffffffe000a02f38 <__stack_chk_fail>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: cooper <cooper.qu@linux.alibaba.com>
Cc: cooper <cooper.qu@linux.alibaba.com>
Cc: Kees Cook <keescook@chromium.org>
---
Change v2:
- Change to -mstack-protector-guard=tls for gcc final define
- Solve compile error by changing position of KBUILD_CFLAGS in
Makefile
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
---
arch/riscv/Kconfig | 7 +++++++
arch/riscv/Makefile | 10 ++++++++++
arch/riscv/include/asm/stackprotector.h | 3 ++-
arch/riscv/kernel/asm-offsets.c | 3 +++
arch/riscv/kernel/process.c | 2 +-
5 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 4b0e308..d98ce29 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -394,6 +394,13 @@ config CMDLINE_FORCE
endchoice
+config CC_HAVE_STACKPROTECTOR_TLS
+ def_bool $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=0)
+
+config STACKPROTECTOR_PER_TASK
+ def_bool y
+ depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS
+
endmenu
config BUILTIN_DTB
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index fb6e37d..f5f8ee9 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -68,6 +68,16 @@ KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax)
# architectures. It's faster to have GCC emit only aligned accesses.
KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
+ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y)
+prepare: stack_protector_prepare
+stack_protector_prepare: prepare0
+ $(eval KBUILD_CFLAGS += -mstack-protector-guard=tls \
+ -mstack-protector-guard-reg=tp \
+ -mstack-protector-guard-offset=$(shell \
+ awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \
+ include/generated/asm-offsets.h))
+endif
+
# arch specific predefines for sparse
CHECKFLAGS += -D__riscv -D__riscv_xlen=$(BITS)
diff --git a/arch/riscv/include/asm/stackprotector.h b/arch/riscv/include/asm/stackprotector.h
index 8e1ef2c..bda4d83 100644
--- a/arch/riscv/include/asm/stackprotector.h
+++ b/arch/riscv/include/asm/stackprotector.h
@@ -28,6 +28,7 @@ static __always_inline void boot_init_stack_canary(void)
canary &= CANARY_MASK;
current->stack_canary = canary;
- __stack_chk_guard = current->stack_canary;
+ if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK))
+ __stack_chk_guard = current->stack_canary;
}
#endif /* _ASM_RISCV_STACKPROTECTOR_H */
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index 07cb9c1..999b465 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -29,6 +29,9 @@ void asm_offsets(void)
OFFSET(TASK_THREAD_S11, task_struct, thread.s[11]);
OFFSET(TASK_THREAD_SP, task_struct, thread.sp);
OFFSET(TASK_STACK, task_struct, stack);
+#ifdef CONFIG_STACKPROTECTOR
+ OFFSET(TSK_STACK_CANARY, task_struct, stack_canary);
+#endif
OFFSET(TASK_TI, task_struct, thread_info);
OFFSET(TASK_TI_FLAGS, task_struct, thread_info.flags);
OFFSET(TASK_TI_PREEMPT_COUNT, task_struct, thread_info.preempt_count);
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 6548929..cb4ac65 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -24,7 +24,7 @@
register unsigned long gp_in_global __asm__("gp");
-#ifdef CONFIG_STACKPROTECTOR
+#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
#include <linux/stackprotector.h>
unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v2 1/2] riscv: Add STACKPROTECTOR supported
2020-07-09 7:28 [PATCH v2 1/2] riscv: Add STACKPROTECTOR supported guoren
2020-07-09 7:28 ` [PATCH v2 2/2] riscv: Enable per-task stack canaries guoren
@ 2020-07-09 18:36 ` kernel test robot
2020-07-09 23:14 ` Guo Ren
1 sibling, 1 reply; 4+ messages in thread
From: kernel test robot @ 2020-07-09 18:36 UTC (permalink / raw)
To: guoren, palmerdabbelt, paul.walmsley, anup, greentime.hu,
zong.li, me, bjorn.topel, atish.patra
Cc: kbuild-all, linux-riscv, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2785 bytes --]
Hi,
I love your patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v5.8-rc4 next-20200709]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/guoren-kernel-org/riscv-Add-STACKPROTECTOR-supported/20200709-153112
base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 0bddd227f3dc55975e2b8dfa7fc6f959b062a2c7
config: riscv-randconfig-s031-20200709 (attached as .config)
compiler: riscv32-linux-gcc (GCC) 9.3.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# apt-get install sparse
# sparse version: v0.6.2-37-gc9676a3b-dirty
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=riscv
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
In file included from include/linux/stackprotector.h:10,
from arch/riscv/kernel/process.c:28:
arch/riscv/include/asm/stackprotector.h: In function 'boot_init_stack_canary':
>> arch/riscv/include/asm/stackprotector.h:26:23: warning: left shift count >= width of type [-Wshift-count-overflow]
26 | canary += tsc + (tsc << 32UL);
| ^~
arch/riscv/kernel/process.c: At top level:
arch/riscv/kernel/process.c:42:6: warning: no previous prototype for 'show_regs' [-Wmissing-prototypes]
42 | void show_regs(struct pt_regs *regs)
| ^~~~~~~~~
arch/riscv/kernel/process.c:103:5: warning: no previous prototype for 'arch_dup_task_struct' [-Wmissing-prototypes]
103 | int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
| ^~~~~~~~~~~~~~~~~~~~
vim +26 arch/riscv/include/asm/stackprotector.h
11
12 /*
13 * Initialize the stackprotector canary value.
14 *
15 * NOTE: this must only be called from functions that never return,
16 * and it must always be inlined.
17 */
18 static __always_inline void boot_init_stack_canary(void)
19 {
20 unsigned long canary;
21 unsigned long tsc;
22
23 /* Try to get a semi random initial value. */
24 get_random_bytes(&canary, sizeof(canary));
25 tsc = get_cycles();
> 26 canary += tsc + (tsc << 32UL);
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 26898 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread