arch/arm64/include/asm/pointer_auth.h

   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 #define PR_PAC_ENABLED_KEYS_MASK                                               \
  14         (PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
  15
  16 #ifdef CONFIG_ARM64_PTR_AUTH
  17 /*
  18  * Each key is a 128-bit quantity which is split across a pair of 64-bit
  19  * registers (Lo and Hi).
  20  */
  21 struct ptrauth_key {
  22         unsigned long lo, hi;
  23 };
  24
  25 /*
  26  * We give each process its own keys, which are shared by all threads. The keys
  27  * are inherited upon fork(), and reinitialised upon exec*().
  28  */
  29 struct ptrauth_keys_user {
  30         struct ptrauth_key apia;
  31         struct ptrauth_key apib;
  32         struct ptrauth_key apda;
  33         struct ptrauth_key apdb;
  34         struct ptrauth_key apga;
  35 };
  36
  37 #define __ptrauth_key_install_nosync(k, v)                      \
  38 do {                                                            \
  39         struct ptrauth_key __pki_v = (v);                       \
  40         write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);     \
  41         write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);     \
  42 } while (0)
  43
  44 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
  45
  46 struct ptrauth_keys_kernel {
  47         struct ptrauth_key apia;
  48 };
  49
  50 static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
  51 {
  52         if (system_supports_address_auth())
  53                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  54 }
  55
  56 static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
  57 {
  58         if (!system_supports_address_auth())
  59                 return;
  60
  61         __ptrauth_key_install_nosync(APIA, keys->apia);
  62         isb();
  63 }
  64
  65 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
  66
  67 static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
  68 {
  69         if (system_supports_address_auth()) {
  70                 __ptrauth_key_install_nosync(APIB, keys->apib);
  71                 __ptrauth_key_install_nosync(APDA, keys->apda);
  72                 __ptrauth_key_install_nosync(APDB, keys->apdb);
  73         }
  74
  75         if (system_supports_generic_auth())
  76                 __ptrauth_key_install_nosync(APGA, keys->apga);
  77 }
  78
  79 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
  80 {
  81         if (system_supports_address_auth()) {
  82                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  83                 get_random_bytes(&keys->apib, sizeof(keys->apib));
  84                 get_random_bytes(&keys->apda, sizeof(keys->apda));
  85                 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
  86         }
  87
  88         if (system_supports_generic_auth())
  89                 get_random_bytes(&keys->apga, sizeof(keys->apga));
  90
  91         ptrauth_keys_install_user(keys);
  92 }
  93
  94 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
  95
  96 extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
  97                                     unsigned long enabled);
  98 extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
  99
 100 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
 101 {
 102         return ptrauth_clear_pac(ptr);
 103 }
 104
 105 static __always_inline void ptrauth_enable(void)
 106 {
 107         if (!system_supports_address_auth())
 108                 return;
 109         sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
 110                                         SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
 111         isb();
 112 }
 113
 114 #define ptrauth_suspend_exit()                                                 \
 115         ptrauth_keys_install_user(&current->thread.keys_user)
 116
 117 #define ptrauth_thread_init_user()                                             \
 118         do {                                                                   \
 119                 ptrauth_keys_init_user(&current->thread.keys_user);            \
 120                                                                                \
 121                 /* enable all keys */                                          \
 122                 if (system_supports_address_auth())                            \
 123                         ptrauth_set_enabled_keys(current,                      \
 124                                                  PR_PAC_ENABLED_KEYS_MASK,     \
 125                                                  PR_PAC_ENABLED_KEYS_MASK);    \
 126         } while (0)
 127
 128 #define ptrauth_thread_switch_user(tsk)                                        \
 129         ptrauth_keys_install_user(&(tsk)->thread.keys_user)
 130
 131 #else /* CONFIG_ARM64_PTR_AUTH */
 132 #define ptrauth_enable()
 133 #define ptrauth_prctl_reset_keys(tsk, arg)      (-EINVAL)
 134 #define ptrauth_set_enabled_keys(tsk, keys, enabled)    (-EINVAL)
 135 #define ptrauth_get_enabled_keys(tsk)   (-EINVAL)
 136 #define ptrauth_strip_insn_pac(lr)      (lr)
 137 #define ptrauth_suspend_exit()
 138 #define ptrauth_thread_init_user()
 139 #define ptrauth_thread_switch_user(tsk)
 140 #endif /* CONFIG_ARM64_PTR_AUTH */
 141
 142 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
 143 #define ptrauth_thread_init_kernel(tsk)                                 \
 144         ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
 145 #define ptrauth_thread_switch_kernel(tsk)                               \
 146         ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
 147 #else
 148 #define ptrauth_thread_init_kernel(tsk)
 149 #define ptrauth_thread_switch_kernel(tsk)
 150 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
 151
 152 #endif /* __ASM_POINTER_AUTH_H */