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/prctl.h>
7 #include <linux/random.h>
8 
9 #include <asm/cpufeature.h>
10 #include <asm/memory.h>
11 #include <asm/sysreg.h>
12 
13 #ifdef CONFIG_ARM64_PTR_AUTH
14 /*
15  * Each key is a 128-bit quantity which is split across a pair of 64-bit
16  * registers (Lo and Hi).
17  */
18 struct ptrauth_key {
19 	unsigned long lo, hi;
20 };
21 
22 /*
23  * We give each process its own keys, which are shared by all threads. The keys
24  * are inherited upon fork(), and reinitialised upon exec*().
25  */
26 struct ptrauth_keys_user {
27 	struct ptrauth_key apia;
28 	struct ptrauth_key apib;
29 	struct ptrauth_key apda;
30 	struct ptrauth_key apdb;
31 	struct ptrauth_key apga;
32 };
33 
34 struct ptrauth_keys_kernel {
35 	struct ptrauth_key apia;
36 };
37 
38 #define __ptrauth_key_install_nosync(k, v)			\
39 do {								\
40 	struct ptrauth_key __pki_v = (v);			\
41 	write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);	\
42 	write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);	\
43 } while (0)
44 
45 static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
46 {
47 	if (system_supports_address_auth()) {
48 		__ptrauth_key_install_nosync(APIB, keys->apib);
49 		__ptrauth_key_install_nosync(APDA, keys->apda);
50 		__ptrauth_key_install_nosync(APDB, keys->apdb);
51 	}
52 
53 	if (system_supports_generic_auth())
54 		__ptrauth_key_install_nosync(APGA, keys->apga);
55 }
56 
57 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
58 {
59 	if (system_supports_address_auth()) {
60 		get_random_bytes(&keys->apia, sizeof(keys->apia));
61 		get_random_bytes(&keys->apib, sizeof(keys->apib));
62 		get_random_bytes(&keys->apda, sizeof(keys->apda));
63 		get_random_bytes(&keys->apdb, sizeof(keys->apdb));
64 	}
65 
66 	if (system_supports_generic_auth())
67 		get_random_bytes(&keys->apga, sizeof(keys->apga));
68 
69 	ptrauth_keys_install_user(keys);
70 }
71 
72 static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
73 {
74 	if (system_supports_address_auth())
75 		get_random_bytes(&keys->apia, sizeof(keys->apia));
76 }
77 
78 static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
79 {
80 	if (!system_supports_address_auth())
81 		return;
82 
83 	__ptrauth_key_install_nosync(APIA, keys->apia);
84 	isb();
85 }
86 
87 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
88 
89 extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
90 				    unsigned long enabled);
91 extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
92 
93 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
94 {
95 	return ptrauth_clear_pac(ptr);
96 }
97 
98 static __always_inline void ptrauth_enable(void)
99 {
100 	if (!system_supports_address_auth())
101 		return;
102 	sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
103 					SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
104 	isb();
105 }
106 
107 #define ptrauth_suspend_exit()                                                 \
108 	ptrauth_keys_install_user(&current->thread.keys_user)
109 
110 #define ptrauth_thread_init_user()                                             \
111 	do {                                                                   \
112 		ptrauth_keys_init_user(&current->thread.keys_user);            \
113 									       \
114 		/* enable all keys */                                          \
115 		if (system_supports_address_auth())                            \
116 			set_task_sctlr_el1(current->thread.sctlr_user |        \
117 					   SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |   \
118 					   SCTLR_ELx_ENDA | SCTLR_ELx_ENDB);   \
119 	} while (0)
120 
121 #define ptrauth_thread_switch_user(tsk)                                        \
122 	ptrauth_keys_install_user(&(tsk)->thread.keys_user)
123 
124 #define ptrauth_thread_init_kernel(tsk)					\
125 	ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
126 #define ptrauth_thread_switch_kernel(tsk)				\
127 	ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
128 
129 #else /* CONFIG_ARM64_PTR_AUTH */
130 #define ptrauth_enable()
131 #define ptrauth_prctl_reset_keys(tsk, arg)	(-EINVAL)
132 #define ptrauth_set_enabled_keys(tsk, keys, enabled)	(-EINVAL)
133 #define ptrauth_get_enabled_keys(tsk)	(-EINVAL)
134 #define ptrauth_strip_insn_pac(lr)	(lr)
135 #define ptrauth_suspend_exit()
136 #define ptrauth_thread_init_user()
137 #define ptrauth_thread_init_kernel(tsk)
138 #define ptrauth_thread_switch_user(tsk)
139 #define ptrauth_thread_switch_kernel(tsk)
140 #endif /* CONFIG_ARM64_PTR_AUTH */
141 
142 #define PR_PAC_ENABLED_KEYS_MASK                                               \
143 	(PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
144 
145 #endif /* __ASM_POINTER_AUTH_H */
146