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c743f38013
This is the very basic stuff without the changing canary upon task switch yet. Just the Kconfig option and a constant canary value initialized at boot time. Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
39 lines
1.1 KiB
C
39 lines
1.1 KiB
C
/*
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* GCC stack protector support.
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*
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* Stack protector works by putting predefined pattern at the start of
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* the stack frame and verifying that it hasn't been overwritten when
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* returning from the function. The pattern is called stack canary
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* and gcc expects it to be defined by a global variable called
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* "__stack_chk_guard" on ARM. This unfortunately means that on SMP
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* we cannot have a different canary value per task.
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*/
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#ifndef _ASM_STACKPROTECTOR_H
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#define _ASM_STACKPROTECTOR_H 1
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#include <linux/random.h>
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#include <linux/version.h>
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extern unsigned long __stack_chk_guard;
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/*
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* Initialize the stackprotector canary value.
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*
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* NOTE: this must only be called from functions that never return,
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* and it must always be inlined.
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*/
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static __always_inline void boot_init_stack_canary(void)
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{
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unsigned long canary;
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/* Try to get a semi random initial value. */
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get_random_bytes(&canary, sizeof(canary));
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canary ^= LINUX_VERSION_CODE;
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current->stack_canary = canary;
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__stack_chk_guard = current->stack_canary;
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}
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#endif /* _ASM_STACKPROTECTOR_H */
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