From 36ecafc5ad17861e2bc1fb12af4cc97680e25942 Mon Sep 17 00:00:00 2001 From: Gregory Fong Date: Wed, 12 Jun 2013 17:08:54 +0000 Subject: MIPS: initial stack protector support Implements basic stack protector support based on ARM version in c743f38013aeff58ef6252601e397b5ba281c633 , with Kconfig option, constant canary value set at boot time, and script to check if compiler actually supports stack protector. Tested by creating a kernel module that writes past end of char[]. Signed-off-by: Gregory Fong Cc: linux-mips@linux-mips.org Cc: Filippo Arcidiacono Cc: Carmelo Amoroso Patchwork: https://patchwork.linux-mips.org/patch/5448/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/stackprotector.h | 40 ++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 arch/mips/include/asm/stackprotector.h (limited to 'arch/mips/include/asm/stackprotector.h') diff --git a/arch/mips/include/asm/stackprotector.h b/arch/mips/include/asm/stackprotector.h new file mode 100644 index 000000000000..eb9b1035e926 --- /dev/null +++ b/arch/mips/include/asm/stackprotector.h @@ -0,0 +1,40 @@ +/* + * GCC stack protector support. + * + * (This is directly adopted from the ARM implementation) + * + * Stack protector works by putting predefined pattern at the start of + * the stack frame and verifying that it hasn't been overwritten when + * returning from the function. The pattern is called stack canary + * and gcc expects it to be defined by a global variable called + * "__stack_chk_guard" on MIPS. This unfortunately means that on SMP + * we cannot have a different canary value per task. + */ + +#ifndef _ASM_STACKPROTECTOR_H +#define _ASM_STACKPROTECTOR_H 1 + +#include +#include + +extern unsigned long __stack_chk_guard; + +/* + * Initialize the stackprotector canary value. + * + * NOTE: this must only be called from functions that never return, + * and it must always be inlined. + */ +static __always_inline void boot_init_stack_canary(void) +{ + unsigned long canary; + + /* Try to get a semi random initial value. */ + get_random_bytes(&canary, sizeof(canary)); + canary ^= LINUX_VERSION_CODE; + + current->stack_canary = canary; + __stack_chk_guard = current->stack_canary; +} + +#endif /* _ASM_STACKPROTECTOR_H */ -- cgit v1.2.3-59-g8ed1b