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1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | /* | |
3 | * Return hooking with list-based shadow stack. | |
4 | */ | |
5 | #ifndef _LINUX_RETHOOK_H | |
6 | #define _LINUX_RETHOOK_H | |
7 | ||
8 | #include <linux/compiler.h> | |
9 | #include <linux/freelist.h> | |
10 | #include <linux/kallsyms.h> | |
11 | #include <linux/llist.h> | |
12 | #include <linux/rcupdate.h> | |
13 | #include <linux/refcount.h> | |
14 | ||
15 | struct rethook_node; | |
16 | ||
17 | typedef void (*rethook_handler_t) (struct rethook_node *, void *, struct pt_regs *); | |
18 | ||
19 | /** | |
20 | * struct rethook - The rethook management data structure. | |
21 | * @data: The user-defined data storage. | |
22 | * @handler: The user-defined return hook handler. | |
23 | * @pool: The pool of struct rethook_node. | |
24 | * @ref: The reference counter. | |
25 | * @rcu: The rcu_head for deferred freeing. | |
26 | * | |
27 | * Don't embed to another data structure, because this is a self-destructive | |
28 | * data structure when all rethook_node are freed. | |
29 | */ | |
30 | struct rethook { | |
31 | void *data; | |
32 | rethook_handler_t handler; | |
33 | struct freelist_head pool; | |
34 | refcount_t ref; | |
35 | struct rcu_head rcu; | |
36 | }; | |
37 | ||
38 | /** | |
39 | * struct rethook_node - The rethook shadow-stack entry node. | |
40 | * @freelist: The freelist, linked to struct rethook::pool. | |
41 | * @rcu: The rcu_head for deferred freeing. | |
42 | * @llist: The llist, linked to a struct task_struct::rethooks. | |
43 | * @rethook: The pointer to the struct rethook. | |
44 | * @ret_addr: The storage for the real return address. | |
45 | * @frame: The storage for the frame pointer. | |
46 | * | |
47 | * You can embed this to your extended data structure to store any data | |
48 | * on each entry of the shadow stack. | |
49 | */ | |
50 | struct rethook_node { | |
51 | union { | |
52 | struct freelist_node freelist; | |
53 | struct rcu_head rcu; | |
54 | }; | |
55 | struct llist_node llist; | |
56 | struct rethook *rethook; | |
57 | unsigned long ret_addr; | |
58 | unsigned long frame; | |
59 | }; | |
60 | ||
61 | struct rethook *rethook_alloc(void *data, rethook_handler_t handler); | |
62 | void rethook_free(struct rethook *rh); | |
63 | void rethook_add_node(struct rethook *rh, struct rethook_node *node); | |
64 | struct rethook_node *rethook_try_get(struct rethook *rh); | |
65 | void rethook_recycle(struct rethook_node *node); | |
66 | void rethook_hook(struct rethook_node *node, struct pt_regs *regs, bool mcount); | |
67 | unsigned long rethook_find_ret_addr(struct task_struct *tsk, unsigned long frame, | |
68 | struct llist_node **cur); | |
69 | ||
70 | /* Arch dependent code must implement arch_* and trampoline code */ | |
71 | void arch_rethook_prepare(struct rethook_node *node, struct pt_regs *regs, bool mcount); | |
72 | void arch_rethook_trampoline(void); | |
73 | ||
74 | /** | |
75 | * is_rethook_trampoline() - Check whether the address is rethook trampoline | |
76 | * @addr: The address to be checked | |
77 | * | |
78 | * Return true if the @addr is the rethook trampoline address. | |
79 | */ | |
80 | static inline bool is_rethook_trampoline(unsigned long addr) | |
81 | { | |
82 | return addr == (unsigned long)dereference_symbol_descriptor(arch_rethook_trampoline); | |
83 | } | |
84 | ||
85 | /* If the architecture needs to fixup the return address, implement it. */ | |
86 | void arch_rethook_fixup_return(struct pt_regs *regs, | |
87 | unsigned long correct_ret_addr); | |
88 | ||
89 | /* Generic trampoline handler, arch code must prepare asm stub */ | |
90 | unsigned long rethook_trampoline_handler(struct pt_regs *regs, | |
91 | unsigned long frame); | |
92 | ||
93 | #ifdef CONFIG_RETHOOK | |
94 | void rethook_flush_task(struct task_struct *tk); | |
95 | #else | |
96 | #define rethook_flush_task(tsk) do { } while (0) | |
97 | #endif | |
98 | ||
99 | #endif | |
100 |