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
   7 #include <asm/cpufeature.h>
   8 #include <asm/memory.h>
   9 #include <asm/sysreg.h>
  10
  11 #ifdef CONFIG_ARM64_PTR_AUTH
  12 /*
  13  * Each key is a 128-bit quantity which is split across a pair of 64-bit
  14  * registers (Lo and Hi).
  15  */
  16 struct ptrauth_key {
  17         unsigned long lo, hi;
  18 };
  19
  20 /*
  21  * We give each process its own keys, which are shared by all threads. The keys
  22  * are inherited upon fork(), and reinitialised upon exec*().
  23  */
  24 struct ptrauth_keys {
  25         struct ptrauth_key apia;
  26         struct ptrauth_key apib;
  27         struct ptrauth_key apda;
  28         struct ptrauth_key apdb;
  29         struct ptrauth_key apga;
  30 };
  31
  32 /*
  33  * Only include random.h once ptrauth_keys_* structures are defined
  34  * to avoid yet another circular include hell (random.h * ends up
  35  * including asm/smp.h, which requires ptrauth_keys_kernel).
  36  */
  37 #include <linux/random.h>
  38
  39 static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
  40 {
  41         if (system_supports_address_auth()) {
  42                 get_random_bytes(&keys->apia, sizeof(keys->apia));
  43                 get_random_bytes(&keys->apib, sizeof(keys->apib));
  44                 get_random_bytes(&keys->apda, sizeof(keys->apda));
  45                 get_random_bytes(&keys->apdb, sizeof(keys->apdb));
  46         }
  47
  48         if (system_supports_generic_auth())
  49                 get_random_bytes(&keys->apga, sizeof(keys->apga));
  50 }
  51
  52 #define __ptrauth_key_install(k, v)                             \
  53 do {                                                            \
  54         struct ptrauth_key __pki_v = (v);                       \
  55         write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1);     \
  56         write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1);     \
  57 } while (0)
  58
  59 static inline void ptrauth_keys_switch(struct ptrauth_keys *keys)
  60 {
  61         if (system_supports_address_auth()) {
  62                 __ptrauth_key_install(APIA, keys->apia);
  63                 __ptrauth_key_install(APIB, keys->apib);
  64                 __ptrauth_key_install(APDA, keys->apda);
  65                 __ptrauth_key_install(APDB, keys->apdb);
  66         }
  67
  68         if (system_supports_generic_auth())
  69                 __ptrauth_key_install(APGA, keys->apga);
  70 }
  71
  72 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
  73
  74 /*
  75  * The EL0 pointer bits used by a pointer authentication code.
  76  * This is dependent on TBI0 being enabled, or bits 63:56 would also apply.
  77  */
  78 #define ptrauth_user_pac_mask() GENMASK(54, vabits_actual)
  79
  80 /* Only valid for EL0 TTBR0 instruction pointers */
  81 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
  82 {
  83         return ptr & ~ptrauth_user_pac_mask();
  84 }
  85
  86 #define ptrauth_thread_init_user(tsk)                                   \
  87 do {                                                                    \
  88         struct task_struct *__ptiu_tsk = (tsk);                         \
  89         ptrauth_keys_init(&__ptiu_tsk->thread.keys_user);               \
  90         ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user);             \
  91 } while (0)
  92
  93 #define ptrauth_thread_switch(tsk)      \
  94         ptrauth_keys_switch(&(tsk)->thread.keys_user)
  95
  96 #else /* CONFIG_ARM64_PTR_AUTH */
  97 #define ptrauth_prctl_reset_keys(tsk, arg)      (-EINVAL)
  98 #define ptrauth_strip_insn_pac(lr)      (lr)
  99 #define ptrauth_thread_init_user(tsk)
 100 #define ptrauth_thread_switch(tsk)
 101 #endif /* CONFIG_ARM64_PTR_AUTH */
 102
 103 #endif /* __ASM_POINTER_AUTH_H */