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 { 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 static inline void ptrauth_keys_init(struct ptrauth_keys *keys) 34 { 35 if (system_supports_address_auth()) { 36 get_random_bytes(&keys->apia, sizeof(keys->apia)); 37 get_random_bytes(&keys->apib, sizeof(keys->apib)); 38 get_random_bytes(&keys->apda, sizeof(keys->apda)); 39 get_random_bytes(&keys->apdb, sizeof(keys->apdb)); 40 } 41 42 if (system_supports_generic_auth()) 43 get_random_bytes(&keys->apga, sizeof(keys->apga)); 44 } 45 46 #define __ptrauth_key_install(k, v) \ 47 do { \ 48 struct ptrauth_key __pki_v = (v); \ 49 write_sysreg_s(__pki_v.lo, SYS_ ## k ## KEYLO_EL1); \ 50 write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \ 51 } while (0) 52 53 static inline void ptrauth_keys_switch(struct ptrauth_keys *keys) 54 { 55 if (system_supports_address_auth()) { 56 __ptrauth_key_install(APIA, keys->apia); 57 __ptrauth_key_install(APIB, keys->apib); 58 __ptrauth_key_install(APDA, keys->apda); 59 __ptrauth_key_install(APDB, keys->apdb); 60 } 61 62 if (system_supports_generic_auth()) 63 __ptrauth_key_install(APGA, keys->apga); 64 } 65 66 extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg); 67 68 /* 69 * The EL0 pointer bits used by a pointer authentication code. 70 * This is dependent on TBI0 being enabled, or bits 63:56 would also apply. 71 */ 72 #define ptrauth_user_pac_mask() GENMASK(54, vabits_user) 73 74 /* Only valid for EL0 TTBR0 instruction pointers */ 75 static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr) 76 { 77 return ptr & ~ptrauth_user_pac_mask(); 78 } 79 80 #define ptrauth_thread_init_user(tsk) \ 81 do { \ 82 struct task_struct *__ptiu_tsk = (tsk); \ 83 ptrauth_keys_init(&__ptiu_tsk->thread.keys_user); \ 84 ptrauth_keys_switch(&__ptiu_tsk->thread.keys_user); \ 85 } while (0) 86 87 #define ptrauth_thread_switch(tsk) \ 88 ptrauth_keys_switch(&(tsk)->thread.keys_user) 89 90 #else /* CONFIG_ARM64_PTR_AUTH */ 91 #define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL) 92 #define ptrauth_strip_insn_pac(lr) (lr) 93 #define ptrauth_thread_init_user(tsk) 94 #define ptrauth_thread_switch(tsk) 95 #endif /* CONFIG_ARM64_PTR_AUTH */ 96 97 #endif /* __ASM_POINTER_AUTH_H */ 98