84 lines
2.1 KiB
C
84 lines
2.1 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_STACKLEAK_H
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#define _LINUX_STACKLEAK_H
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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/*
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* Check that the poison value points to the unused hole in the
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* virtual memory map for your platform.
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*/
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#define STACKLEAK_POISON -0xBEEF
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#define STACKLEAK_SEARCH_DEPTH 128
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#ifdef CONFIG_GCC_PLUGIN_STACKLEAK
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#include <asm/stacktrace.h>
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/*
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* The lowest address on tsk's stack which we can plausibly erase.
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*/
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static __always_inline unsigned long
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stackleak_task_low_bound(const struct task_struct *tsk)
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{
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/*
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* The lowest unsigned long on the task stack contains STACK_END_MAGIC,
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* which we must not corrupt.
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*/
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return (unsigned long)end_of_stack(tsk) + sizeof(unsigned long);
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}
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/*
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* The address immediately after the highest address on tsk's stack which we
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* can plausibly erase.
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*/
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static __always_inline unsigned long
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stackleak_task_high_bound(const struct task_struct *tsk)
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{
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/*
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* The task's pt_regs lives at the top of the task stack and will be
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* overwritten by exception entry, so there's no need to erase them.
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*/
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return (unsigned long)task_pt_regs(tsk);
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}
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/*
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* Find the address immediately above the poisoned region of the stack, where
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* that region falls between 'low' (inclusive) and 'high' (exclusive).
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*/
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static __always_inline unsigned long
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stackleak_find_top_of_poison(const unsigned long low, const unsigned long high)
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{
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const unsigned int depth = STACKLEAK_SEARCH_DEPTH / sizeof(unsigned long);
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unsigned int poison_count = 0;
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unsigned long poison_high = high;
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unsigned long sp = high;
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while (sp > low && poison_count < depth) {
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sp -= sizeof(unsigned long);
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if (*(unsigned long *)sp == STACKLEAK_POISON) {
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poison_count++;
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} else {
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poison_count = 0;
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poison_high = sp;
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}
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}
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return poison_high;
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}
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static inline void stackleak_task_init(struct task_struct *t)
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{
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t->lowest_stack = stackleak_task_low_bound(t);
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# ifdef CONFIG_STACKLEAK_METRICS
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t->prev_lowest_stack = t->lowest_stack;
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# endif
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}
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#else /* !CONFIG_GCC_PLUGIN_STACKLEAK */
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static inline void stackleak_task_init(struct task_struct *t) { }
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#endif
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#endif
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