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/random.h>
   7
   8 #include <asm/cpufeature.h>
   9 #include <asm/memory.h>
  10 #include <asm/sysreg.h>
  11
  12 #ifdef CONFIG_ARM64_PTR_AUTH
  13 /*
  14  * Each key is a 128-bit quantity which is split across a pair of 64-bit
  15  * registers (Lo and Hi).
  16  */
  17 struct ptrauth_key {
  18         unsigned long lo, hi;
  19 };
  20
  21 /*
  22  * We give each process its own keys, which are shared by all threads. The keys
  23  * are inherited upon fork(), and reinitialised upon exec*().
  24  */
  25 struct ptrauth_keys_user {
  26         struct ptrauth_key apia;
  27         struct ptrauth_key apib;
  28         struct ptrauth_key apda;
  29         struct ptrauth_key apdb;
  30         struct ptrauth_key apga;
  31 };
  32
  33 struct ptrauth_keys_kernel {
  34         struct ptrauth_key apia;
  35 };
  36
  37 static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
  38 {
  39         if (system_supports_address_auth()) {
  40                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  41                 get_random_bytes(&keys->apib, sizeof(keys->apib));
  42                 get_random_bytes(&keys->apda, sizeof(keys->apda));
  43                 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
  44         }
  45
  46         if (system_supports_generic_auth())
  47                 get_random_bytes(&keys->apga, sizeof(keys->apga));
  48 }
  49
  50 #define __ptrauth_key_install_nosync(k, v)                      \
  51 do {                                                            \
  52         struct ptrauth_key __pki_v = (v);                       \
  53         write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);     \
  54         write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);     \
  55 } while (0)
  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 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
  73
  74 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
  75 {
  76         return ptrauth_clear_pac(ptr);
  77 }
  78
  79 #define ptrauth_thread_init_user(tsk)                                   \
  80         ptrauth_keys_init_user(&(tsk)->thread.keys_user)
  81 #define ptrauth_thread_init_kernel(tsk)                                 \
  82         ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
  83 #define ptrauth_thread_switch_kernel(tsk)                               \
  84         ptrauth_keys_switch_kernel(&(tsk)->thread.keys_kernel)
  85
  86 #else /* CONFIG_ARM64_PTR_AUTH */
  87 #define ptrauth_prctl_reset_keys(tsk, arg)      (-EINVAL)
  88 #define ptrauth_strip_insn_pac(lr)      (lr)
  89 #define ptrauth_thread_init_user(tsk)
  90 #define ptrauth_thread_init_kernel(tsk)
  91 #define ptrauth_thread_switch_kernel(tsk)
  92 #endif /* CONFIG_ARM64_PTR_AUTH */
  93
  94 #endif /* __ASM_POINTER_AUTH_H */