1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __ASM_POINTER_AUTH_H
3 #define __ASM_POINTER_AUTH_H
4 
5 #include <linux/bitops.h>
6 #include <linux/random.h>
7 
8 #include <asm/cpufeature.h>
9 #include <asm/memory.h>
10 #include <asm/sysreg.h>
11 
12 #ifdef CONFIG_ARM64_PTR_AUTH
13 /*
14  * Each key is a 128-bit quantity which is split across a pair of 64-bit
15  * registers (Lo and Hi).
16  */
17 struct ptrauth_key {
18 	unsigned long lo, hi;
19 };
20 
21 /*
22  * We give each process its own keys, which are shared by all threads. The keys
23  * are inherited upon fork(), and reinitialised upon exec*().
24  */
25 struct ptrauth_keys_user {
26 	struct ptrauth_key apia;
27 	struct ptrauth_key apib;
28 	struct ptrauth_key apda;
29 	struct ptrauth_key apdb;
30 	struct ptrauth_key apga;
31 };
32 
33 struct ptrauth_keys_kernel {
34 	struct ptrauth_key apia;
35 };
36 
37 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
38 {
39 	if (system_supports_address_auth()) {
40 		get_random_bytes(&keys->apia, sizeof(keys->apia));
41 		get_random_bytes(&keys->apib, sizeof(keys->apib));
42 		get_random_bytes(&keys->apda, sizeof(keys->apda));
43 		get_random_bytes(&keys->apdb, sizeof(keys->apdb));
44 	}
45 
46 	if (system_supports_generic_auth())
47 		get_random_bytes(&keys->apga, sizeof(keys->apga));
48 }
49 
50 #define __ptrauth_key_install_nosync(k, v)			\
51 do {								\
52 	struct ptrauth_key __pki_v = (v);			\
53 	write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);	\
54 	write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);	\
55 } while (0)
56 
57 static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
58 {
59 	if (system_supports_address_auth())
60 		get_random_bytes(&keys->apia, sizeof(keys->apia));
61 }
62 
63 static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
64 {
65 	if (!system_supports_address_auth())
66 		return;
67 
68 	__ptrauth_key_install_nosync(APIA, keys->apia);
69 	isb();
70 }
71 
72 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
73 
74 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
75 {
76 	return ptrauth_clear_pac(ptr);
77 }
78 
79 static __always_inline void ptrauth_enable(void)
80 {
81 	if (!system_supports_address_auth())
82 		return;
83 	sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
84 					SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
85 	isb();
86 }
87 
88 #define ptrauth_thread_init_user(tsk)					\
89 	ptrauth_keys_init_user(&(tsk)->thread.keys_user)
90 #define ptrauth_thread_init_kernel(tsk)					\
91 	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
92 #define ptrauth_thread_switch_kernel(tsk)				\
93 	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
94 
95 #else /* CONFIG_ARM64_PTR_AUTH */
96 #define ptrauth_enable()
97 #define ptrauth_prctl_reset_keys(tsk, arg)	(-EINVAL)
98 #define ptrauth_strip_insn_pac(lr)	(lr)
99 #define ptrauth_thread_init_user(tsk)
100 #define ptrauth_thread_init_kernel(tsk)
101 #define ptrauth_thread_switch_kernel(tsk)
102 #endif /* CONFIG_ARM64_PTR_AUTH */
103 
104 #endif /* __ASM_POINTER_AUTH_H */
105