40 lines
1.1 KiB
C
40 lines
1.1 KiB
C
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#ifndef _ASM_STACKPROTECTOR_H
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#define _ASM_STACKPROTECTOR_H 1
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#include <asm/tsc.h>
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#include <asm/pda.h>
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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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u64 canary;
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u64 tsc;
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/*
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* If we're the non-boot CPU, nothing set the PDA stack
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* canary up for us - and if we are the boot CPU we have
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* a 0 stack canary. This is a good place for updating
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* it, as we wont ever return from this function (so the
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* invalid canaries already on the stack wont ever
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* trigger).
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*
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* We both use the random pool and the current TSC as a source
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* of randomness. The TSC only matters for very early init,
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* there it already has some randomness on most systems. Later
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* on during the bootup the random pool has true entropy too.
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*/
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get_random_bytes(&canary, sizeof(canary));
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tsc = __native_read_tsc();
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canary += tsc + (tsc << 32UL);
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current->stack_canary = canary;
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write_pda(stack_canary, canary);
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}
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#endif
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