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 /*
14 * The EL0/EL1 pointer bits used by a pointer authentication code.
15 * This is dependent on TBI0/TBI1 being enabled, or bits 63:56 would also apply.
16 */
17 #define ptrauth_user_pac_mask() GENMASK_ULL(54, vabits_actual)
18 #define ptrauth_kernel_pac_mask() GENMASK_ULL(63, vabits_actual)
19
20 #define PR_PAC_ENABLED_KEYS_MASK \
21 (PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
22
23 #ifdef CONFIG_ARM64_PTR_AUTH
24 /*
25 * Each key is a 128-bit quantity which is split across a pair of 64-bit
26 * registers (Lo and Hi).
27 */
28 struct ptrauth_key {
29 unsigned long lo, hi;
30 };
31
32 /*
33 * We give each process its own keys, which are shared by all threads. The keys
34 * are inherited upon fork(), and reinitialised upon exec*().
35 */
36 struct ptrauth_keys_user {
37 struct ptrauth_key apia;
38 struct ptrauth_key apib;
39 struct ptrauth_key apda;
40 struct ptrauth_key apdb;
41 struct ptrauth_key apga;
42 };
43
44 #define __ptrauth_key_install_nosync(k, v) \
45 do { \
46 struct ptrauth_key __pki_v = (v); \
47 write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \
48 write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \
49 } while (0)
50
51 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
52
53 struct ptrauth_keys_kernel {
54 struct ptrauth_key apia;
55 };
56
ptrauth_keys_init_kernel(struct ptrauth_keys_kernel * keys)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
ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel * keys)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 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
73
ptrauth_keys_install_user(struct ptrauth_keys_user * keys)74 static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
75 {
76 if (system_supports_address_auth()) {
77 __ptrauth_key_install_nosync(APIB, keys->apib);
78 __ptrauth_key_install_nosync(APDA, keys->apda);
79 __ptrauth_key_install_nosync(APDB, keys->apdb);
80 }
81
82 if (system_supports_generic_auth())
83 __ptrauth_key_install_nosync(APGA, keys->apga);
84 }
85
ptrauth_keys_init_user(struct ptrauth_keys_user * keys)86 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
87 {
88 if (system_supports_address_auth()) {
89 get_random_bytes(&keys->apia, sizeof(keys->apia));
90 get_random_bytes(&keys->apib, sizeof(keys->apib));
91 get_random_bytes(&keys->apda, sizeof(keys->apda));
92 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
93 }
94
95 if (system_supports_generic_auth())
96 get_random_bytes(&keys->apga, sizeof(keys->apga));
97
98 ptrauth_keys_install_user(keys);
99 }
100
101 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
102
103 extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
104 unsigned long enabled);
105 extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
106
ptrauth_enable(void)107 static __always_inline void ptrauth_enable(void)
108 {
109 if (!system_supports_address_auth())
110 return;
111 sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
112 SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
113 isb();
114 }
115
116 #define ptrauth_suspend_exit() \
117 ptrauth_keys_install_user(¤t->thread.keys_user)
118
119 #define ptrauth_thread_init_user() \
120 do { \
121 ptrauth_keys_init_user(¤t->thread.keys_user); \
122 \
123 /* enable all keys */ \
124 if (system_supports_address_auth()) \
125 ptrauth_set_enabled_keys(current, \
126 PR_PAC_ENABLED_KEYS_MASK, \
127 PR_PAC_ENABLED_KEYS_MASK); \
128 } while (0)
129
130 #define ptrauth_thread_switch_user(tsk) \
131 ptrauth_keys_install_user(&(tsk)->thread.keys_user)
132
133 #else /* CONFIG_ARM64_PTR_AUTH */
134 #define ptrauth_enable()
135 #define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL)
136 #define ptrauth_set_enabled_keys(tsk, keys, enabled) (-EINVAL)
137 #define ptrauth_get_enabled_keys(tsk) (-EINVAL)
138 #define ptrauth_suspend_exit()
139 #define ptrauth_thread_init_user()
140 #define ptrauth_thread_switch_user(tsk)
141 #endif /* CONFIG_ARM64_PTR_AUTH */
142
143 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
144 #define ptrauth_thread_init_kernel(tsk) \
145 ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
146 #define ptrauth_thread_switch_kernel(tsk) \
147 ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
148 #else
149 #define ptrauth_thread_init_kernel(tsk)
150 #define ptrauth_thread_switch_kernel(tsk)
151 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
152
153 #endif /* __ASM_POINTER_AUTH_H */
154
