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83 lines
2.1 KiB
83 lines
2.1 KiB
/* 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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