Commit be129842 authored by Kristina Martsenko's avatar Kristina Martsenko Committed by Catalin Marinas
Browse files

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: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarVincenzo Frascino <Vincenzo.Frascino@arm.com>
Signed-off-by: default avatarKristina Martsenko <kristina.martsenko@arm.com>
[Amit: commit msg, re-positioned the patch, comments]
Signed-off-by: default avatarAmit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 91a1b6cc

arch/arm64/include/asm/asm_pointer_auth.h

0 → 100644
+49 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef __ASM_ASM_POINTER_AUTH_H

#define __ASM_ASM_POINTER_AUTH_H



#include <asm/alternative.h>

#include <asm/asm-offsets.h>

#include <asm/cpufeature.h>

#include <asm/sysreg.h>



#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 */

arch/arm64/include/asm/pointer_auth.h

+1 −22
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/kernel/asm-offsets.c

+11 −0
Original line number Diff line number Diff line
@@ -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]));
@@ -127,6 +130,14 @@ int main(void) 
#ifdef CONFIG_ARM_SDE_INTERFACE

  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;

}

arch/arm64/kernel/entry.S

+3 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <asm/alternative.h>

#include <asm/assembler.h>

#include <asm/asm-offsets.h>

#include <asm/asm_pointer_auth.h>

#include <asm/cpufeature.h>

#include <asm/errno.h>

#include <asm/esr.h>
@@ -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

arch/arm64/kernel/pointer_auth.c

+0 −3
Original line number Diff line number Diff line
@@ -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;

}

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