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 #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 #define __ptrauth_key_install_nosync(k, v)                      \
  35 do {                                                            \
  36         struct ptrauth_key __pki_v = (v);                       \
  37         write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);     \
  38         write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);     \
  39 } while (0)
  40
  41 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
  42
  43 struct ptrauth_keys_kernel {
  44         struct ptrauth_key apia;
  45 };
  46
  47 static __always_inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
  48 {
  49         if (system_supports_address_auth())
  50                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  51 }
  52
  53 static __always_inline void ptrauth_keys_switch_kernel(struct ptrauth_keys_kernel *keys)
  54 {
  55         if (!system_supports_address_auth())
  56                 return;
  57
  58         __ptrauth_key_install_nosync(APIA, keys->apia);
  59         isb();
  60 }
  61
  62 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
  63
  64 static inline void ptrauth_keys_install_user(struct ptrauth_keys_user *keys)
  65 {
  66         if (system_supports_address_auth()) {
  67                 __ptrauth_key_install_nosync(APIB, keys->apib);
  68                 __ptrauth_key_install_nosync(APDA, keys->apda);
  69                 __ptrauth_key_install_nosync(APDB, keys->apdb);
  70         }
  71
  72         if (system_supports_generic_auth())
  73                 __ptrauth_key_install_nosync(APGA, keys->apga);
  74 }
  75
  76 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
  77 {
  78         if (system_supports_address_auth()) {
  79                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  80                 get_random_bytes(&keys->apib, sizeof(keys->apib));
  81                 get_random_bytes(&keys->apda, sizeof(keys->apda));
  82                 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
  83         }
  84
  85         if (system_supports_generic_auth())
  86                 get_random_bytes(&keys->apga, sizeof(keys->apga));
  87
  88         ptrauth_keys_install_user(keys);
  89 }
  90
  91 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
  92
  93 extern int ptrauth_set_enabled_keys(struct task_struct *tsk, unsigned long keys,
  94                                     unsigned long enabled);
  95 extern int ptrauth_get_enabled_keys(struct task_struct *tsk);
  96
  97 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
  98 {
  99         return ptrauth_clear_pac(ptr);
 100 }
 101
 102 static __always_inline void ptrauth_enable(void)
 103 {
 104         if (!system_supports_address_auth())
 105                 return;
 106         sysreg_clear_set(sctlr_el1, 0, (SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |
 107                                         SCTLR_ELx_ENDA | SCTLR_ELx_ENDB));
 108         isb();
 109 }
 110
 111 #define ptrauth_suspend_exit()                                                 \
 112         ptrauth_keys_install_user(&current->thread.keys_user)
 113
 114 #define ptrauth_thread_init_user()                                             \
 115         do {                                                                   \
 116                 ptrauth_keys_init_user(&current->thread.keys_user);            \
 117                                                                                \
 118                 /* enable all keys */                                          \
 119                 if (system_supports_address_auth())                            \
 120                         set_task_sctlr_el1(current->thread.sctlr_user |        \
 121                                            SCTLR_ELx_ENIA | SCTLR_ELx_ENIB |   \
 122                                            SCTLR_ELx_ENDA | SCTLR_ELx_ENDB);   \
 123         } while (0)
 124
 125 #define ptrauth_thread_switch_user(tsk)                                        \
 126         ptrauth_keys_install_user(&(tsk)->thread.keys_user)
 127
 128 #else /* CONFIG_ARM64_PTR_AUTH */
 129 #define ptrauth_enable()
 130 #define ptrauth_prctl_reset_keys(tsk, arg)      (-EINVAL)
 131 #define ptrauth_set_enabled_keys(tsk, keys, enabled)    (-EINVAL)
 132 #define ptrauth_get_enabled_keys(tsk)   (-EINVAL)
 133 #define ptrauth_strip_insn_pac(lr)      (lr)
 134 #define ptrauth_suspend_exit()
 135 #define ptrauth_thread_init_user()
 136 #define ptrauth_thread_switch_user(tsk)
 137 #endif /* CONFIG_ARM64_PTR_AUTH */
 138
 139 #ifdef CONFIG_ARM64_PTR_AUTH_KERNEL
 140 #define ptrauth_thread_init_kernel(tsk)                                 \
 141         ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
 142 #define ptrauth_thread_switch_kernel(tsk)                               \
 143         ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
 144 #else
 145 #define ptrauth_thread_init_kernel(tsk)
 146 #define ptrauth_thread_switch_kernel(tsk)
 147 #endif /* CONFIG_ARM64_PTR_AUTH_KERNEL */
 148
 149 #define PR_PAC_ENABLED_KEYS_MASK                                               \
 150         (PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY)
 151
 152 #endif /* __ASM_POINTER_AUTH_H */