| 1 |
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| 2 | |
| 3 | * Return hooking with list-based shadow stack.
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| 4 |
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| 5 | #ifndef _LINUX_RETHOOK_H
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| 6 | #define _LINUX_RETHOOK_H
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| 7 |
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| 8 | #include <linux/compiler.h>
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| 9 | #include <linux/objpool.h>
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| 10 | #include <linux/kallsyms.h>
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| 11 | #include <linux/llist.h>
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| 12 | #include <linux/rcupdate.h>
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| 13 |
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| 14 | struct rethook_node;
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| 15 |
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| 16 | typedef void (*rethook_handler_t) (struct rethook_node *, void *, unsigned long, struct pt_regs *);
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| 17 |
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| 18 | |
| 19 | * struct rethook - The rethook management data structure.
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| 20 | * @data: The user-defined data storage.
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| 21 | * @handler: The user-defined return hook handler.
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| 22 | * @pool: The pool of struct rethook_node.
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| 23 | * @ref: The reference counter.
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| 24 | * @rcu: The rcu_head for deferred freeing.
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| 25 | *
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| 26 | * Don't embed to another data structure, because this is a self-destructive
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| 27 | * data structure when all rethook_node are freed.
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| 28 |
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| 29 | struct rethook {
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| 30 | void *data;
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| 31 | |
| 32 | * To avoid sparse warnings, this uses a raw function pointer with
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| 33 | * __rcu, instead of rethook_handler_t. But this must be same as
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| 34 | * rethook_handler_t.
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| 35 |
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| 36 | void (__rcu *handler) (struct rethook_node *, void *, unsigned long, struct pt_regs *);
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| 37 | struct objpool_head pool;
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| 38 | struct rcu_head rcu;
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| 39 | };
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| 40 |
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| 41 | |
| 42 | * struct rethook_node - The rethook shadow-stack entry node.
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| 43 | * @rcu: The rcu_head for deferred freeing.
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| 44 | * @llist: The llist, linked to a struct task_struct::rethooks.
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| 45 | * @rethook: The pointer to the struct rethook.
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| 46 | * @ret_addr: The storage for the real return address.
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| 47 | * @frame: The storage for the frame pointer.
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| 48 | *
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| 49 | * You can embed this to your extended data structure to store any data
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| 50 | * on each entry of the shadow stack.
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| 51 |
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| 52 | struct rethook_node {
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| 53 | struct rcu_head rcu;
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| 54 | struct llist_node llist;
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| 55 | struct rethook *rethook;
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| 56 | unsigned long ret_addr;
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| 57 | unsigned long frame;
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| 58 | };
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| 59 |
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| 60 | struct rethook *rethook_alloc(void *data, rethook_handler_t handler, int size, int num);
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| 61 | void rethook_stop(struct rethook *rh);
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| 62 | void rethook_free(struct rethook *rh);
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| 63 | struct rethook_node *rethook_try_get(struct rethook *rh);
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| 64 | void rethook_recycle(struct rethook_node *node);
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| 65 | void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount);
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| 66 | unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame,
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| 67 | struct llist_node **cur);
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| 68 |
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| 69 |
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| 70 | void arch_rethook_prepare(struct rethook_node *node, struct pt_regs *regs, bool mcount);
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| 71 | void arch_rethook_trampoline(void);
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| 72 |
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| 73 | |
| 74 | * is_rethook_trampoline() - Check whether the address is rethook trampoline
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| 75 | * @addr: The address to be checked
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| 76 | *
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| 77 | * Return true if the @addr is the rethook trampoline address.
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| 78 |
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| 79 | static inline bool is_rethook_trampoline(unsigned long addr)
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| 80 | {
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| 81 | return addr == (unsigned long)dereference_symbol_descriptor(arch_rethook_trampoline);
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| 82 | }
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| 83 |
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| 84 |
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| 85 | void arch_rethook_fixup_return(struct pt_regs *regs,
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| 86 | unsigned long correct_ret_addr);
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| 87 |
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| 88 |
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| 89 | unsigned long rethook_trampoline_handler(struct pt_regs *regs,
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| 90 | unsigned long frame);
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| 91 |
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| 92 | #ifdef CONFIG_RETHOOK
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| 93 | void rethook_flush_task(struct task_struct *tk);
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| 94 | #else
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| 95 | #define rethook_flush_task(tsk) do { } while (0)
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| 96 | #endif
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| 97 |
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| 98 | #endif
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