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