From be129842566599f2c6f8fbba277c098802cd4b3d Mon Sep 17 00:00:00 2001 From: Kristina Martsenko Date: Fri, 13 Mar 2020 14:34:51 +0530 Subject: [PATCH] arm64: install user ptrauth keys at kernel exit time As we're going to enable pointer auth within the kernel and use a different APIAKey for the kernel itself, so move the user APIAKey switch to EL0 exception return. The other 4 keys could remain switched during task switch, but are also moved to keep things consistent. Reviewed-by: Kees Cook Reviewed-by: James Morse Reviewed-by: Vincenzo Frascino Signed-off-by: Kristina Martsenko [Amit: commit msg, re-positioned the patch, comments] Signed-off-by: Amit Daniel Kachhap Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/asm_pointer_auth.h | 49 +++++++++++++++++++++++++++++++ arch/arm64/include/asm/pointer_auth.h | 23 +-------------- arch/arm64/kernel/asm-offsets.c | 11 +++++++ arch/arm64/kernel/entry.S | 3 ++ arch/arm64/kernel/pointer_auth.c | 3 -- arch/arm64/kernel/process.c | 1 - 6 files changed, 64 insertions(+), 26 deletions(-) create mode 100644 arch/arm64/include/asm/asm_pointer_auth.h diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h new file mode 100644 index 0000000..3482348 --- /dev/null +++ b/arch/arm64/include/asm/asm_pointer_auth.h @@ -0,0 +1,49 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_ASM_POINTER_AUTH_H +#define __ASM_ASM_POINTER_AUTH_H + +#include +#include +#include +#include + +#ifdef CONFIG_ARM64_PTR_AUTH +/* + * thread.keys_user.ap* as offset exceeds the #imm offset range + * so use the base value of ldp as thread.keys_user and offset as + * thread.keys_user.ap*. + */ + .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3 + mov \tmp1, #THREAD_KEYS_USER + add \tmp1, \tsk, \tmp1 +alternative_if_not ARM64_HAS_ADDRESS_AUTH + b .Laddr_auth_skip_\@ +alternative_else_nop_endif + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIA] + msr_s SYS_APIAKEYLO_EL1, \tmp2 + msr_s SYS_APIAKEYHI_EL1, \tmp3 + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APIB] + msr_s SYS_APIBKEYLO_EL1, \tmp2 + msr_s SYS_APIBKEYHI_EL1, \tmp3 + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APDA] + msr_s SYS_APDAKEYLO_EL1, \tmp2 + msr_s SYS_APDAKEYHI_EL1, \tmp3 + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APDB] + msr_s SYS_APDBKEYLO_EL1, \tmp2 + msr_s SYS_APDBKEYHI_EL1, \tmp3 +.Laddr_auth_skip_\@: +alternative_if ARM64_HAS_GENERIC_AUTH + ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_USER_KEY_APGA] + msr_s SYS_APGAKEYLO_EL1, \tmp2 + msr_s SYS_APGAKEYHI_EL1, \tmp3 +alternative_else_nop_endif + .endm + +#else /* CONFIG_ARM64_PTR_AUTH */ + + .macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3 + .endm + +#endif /* CONFIG_ARM64_PTR_AUTH */ + +#endif /* __ASM_ASM_POINTER_AUTH_H */ diff --git a/arch/arm64/include/asm/pointer_auth.h b/arch/arm64/include/asm/pointer_auth.h index 799b079..dabe026 100644 --- a/arch/arm64/include/asm/pointer_auth.h +++ b/arch/arm64/include/asm/pointer_auth.h @@ -50,19 +50,6 @@ do { \ write_sysreg_s(__pki_v.hi, SYS_ ## k ## KEYHI_EL1); \ } while (0) -static inline void ptrauth_keys_switch_user(struct ptrauth_keys_user *keys) -{ - if (system_supports_address_auth()) { - __ptrauth_key_install(APIA, keys->apia); - __ptrauth_key_install(APIB, keys->apib); - __ptrauth_key_install(APDA, keys->apda); - __ptrauth_key_install(APDB, keys->apdb); - } - - if (system_supports_generic_auth()) - __ptrauth_key_install(APGA, keys->apga); -} - extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg); /* @@ -78,20 +65,12 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr) } #define ptrauth_thread_init_user(tsk) \ -do { \ - struct task_struct *__ptiu_tsk = (tsk); \ - ptrauth_keys_init_user(&__ptiu_tsk->thread.keys_user); \ - ptrauth_keys_switch_user(&__ptiu_tsk->thread.keys_user); \ -} while (0) - -#define ptrauth_thread_switch(tsk) \ - ptrauth_keys_switch_user(&(tsk)->thread.keys_user) + ptrauth_keys_init_user(&(tsk)->thread.keys_user) #else /* CONFIG_ARM64_PTR_AUTH */ #define ptrauth_prctl_reset_keys(tsk, arg) (-EINVAL) #define ptrauth_strip_insn_pac(lr) (lr) #define ptrauth_thread_init_user(tsk) -#define ptrauth_thread_switch(tsk) #endif /* CONFIG_ARM64_PTR_AUTH */ #endif /* __ASM_POINTER_AUTH_H */ diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index a5bdce8..7b1ea2a 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -40,6 +40,9 @@ int main(void) #endif BLANK(); DEFINE(THREAD_CPU_CONTEXT, offsetof(struct task_struct, thread.cpu_context)); +#ifdef CONFIG_ARM64_PTR_AUTH + DEFINE(THREAD_KEYS_USER, offsetof(struct task_struct, thread.keys_user)); +#endif BLANK(); DEFINE(S_X0, offsetof(struct pt_regs, regs[0])); DEFINE(S_X2, offsetof(struct pt_regs, regs[2])); @@ -128,5 +131,13 @@ int main(void) DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs)); DEFINE(SDEI_EVENT_PRIORITY, offsetof(struct sdei_registered_event, priority)); #endif +#ifdef CONFIG_ARM64_PTR_AUTH + DEFINE(PTRAUTH_USER_KEY_APIA, offsetof(struct ptrauth_keys_user, apia)); + DEFINE(PTRAUTH_USER_KEY_APIB, offsetof(struct ptrauth_keys_user, apib)); + DEFINE(PTRAUTH_USER_KEY_APDA, offsetof(struct ptrauth_keys_user, apda)); + DEFINE(PTRAUTH_USER_KEY_APDB, offsetof(struct ptrauth_keys_user, apdb)); + DEFINE(PTRAUTH_USER_KEY_APGA, offsetof(struct ptrauth_keys_user, apga)); + BLANK(); +#endif return 0; } diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 9461d81..684e475 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -341,6 +342,8 @@ alternative_else_nop_endif msr cntkctl_el1, x1 4: #endif + ptrauth_keys_install_user tsk, x0, x1, x2 + apply_ssbd 0, x0, x1 .endif diff --git a/arch/arm64/kernel/pointer_auth.c b/arch/arm64/kernel/pointer_auth.c index af5a638..1e77736 100644 --- a/arch/arm64/kernel/pointer_auth.c +++ b/arch/arm64/kernel/pointer_auth.c @@ -19,7 +19,6 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg) if (!arg) { ptrauth_keys_init_user(keys); - ptrauth_keys_switch_user(keys); return 0; } @@ -41,7 +40,5 @@ int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg) if (arg & PR_PAC_APGAKEY) get_random_bytes(&keys->apga, sizeof(keys->apga)); - ptrauth_keys_switch_user(keys); - return 0; } diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 0062605..6140e79 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -512,7 +512,6 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev, contextidr_thread_switch(next); entry_task_switch(next); uao_thread_switch(next); - ptrauth_thread_switch(next); ssbs_thread_switch(next); /* -- 2.7.4