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 /*
  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
  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 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
  73
  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
  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
 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(&current->thread.keys_user)
 118
 119 #define ptrauth_thread_init_user()                                             \
 120         do {                                                                   \
 121                 ptrauth_keys_init_user(&current->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 */