From: Amit Daniel Kachhap <amit.kachhap@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Kees Cook <keescook@chromium.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Will Deacon <will.deacon@arm.com>,
Kristina Martsenko <kristina.martsenko@arm.com>,
James Morse <james.morse@arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
Amit Daniel Kachhap <amit.kachhap@arm.com>,
Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
Dave Martin <Dave.Martin@arm.com>
Subject: [PATCH v2 07/14] arm64: initialize and switch ptrauth kernel keys
Date: Tue, 19 Nov 2019 18:02:19 +0530 [thread overview]
Message-ID: <1574166746-27197-8-git-send-email-amit.kachhap@arm.com> (raw)
In-Reply-To: <1574166746-27197-1-git-send-email-amit.kachhap@arm.com>
From: Kristina Martsenko <kristina.martsenko@arm.com>
Set up keys to use pointer authentication within the kernel. The kernel
will be compiled with APIAKey instructions, the other keys are currently
unused. Each task is given its own APIAKey, which is initialized during
fork. The key is changed during context switch and on kernel entry from
EL0.
The keys for idle threads need to be set before calling any C functions,
because it is not possible to enter and exit a function with different
keys.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com>
[Amit: Modified secondary cores key structure, comments]
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
---
Changes since last version:
* Used "struct ptrauth_keys_kernel" instead of 2 unsigned longs. [James]
* Check secondary data validity for slow cpus. [James]
Link to above discussion: https://www.spinics.net/lists/arm-kernel/msg763623.html
arch/arm64/include/asm/asm_pointer_auth.h | 14 ++++++++++++++
arch/arm64/include/asm/pointer_auth.h | 13 +++++++++++++
arch/arm64/include/asm/processor.h | 1 +
arch/arm64/include/asm/smp.h | 4 ++++
arch/arm64/kernel/asm-offsets.c | 5 +++++
arch/arm64/kernel/entry.S | 3 +++
arch/arm64/kernel/process.c | 2 ++
arch/arm64/kernel/smp.c | 8 ++++++++
arch/arm64/mm/proc.S | 13 +++++++++++++
9 files changed, 63 insertions(+)
diff --git a/arch/arm64/include/asm/asm_pointer_auth.h b/arch/arm64/include/asm/asm_pointer_auth.h
index 3d39788..172548a 100644
--- a/arch/arm64/include/asm/asm_pointer_auth.h
+++ b/arch/arm64/include/asm/asm_pointer_auth.h
@@ -35,11 +35,25 @@ alternative_if ARM64_HAS_GENERIC_AUTH
alternative_else_nop_endif
.endm
+ .macro ptrauth_keys_install_kernel tsk, tmp1, tmp2, tmp3
+ mov \tmp1, #THREAD_KEYS_KERNEL
+ add \tmp1, \tsk, \tmp1
+alternative_if ARM64_HAS_ADDRESS_AUTH
+ ldp \tmp2, \tmp3, [\tmp1, #PTRAUTH_KERNEL_KEY_APIA]
+ msr_s SYS_APIAKEYLO_EL1, \tmp2
+ msr_s SYS_APIAKEYHI_EL1, \tmp3
+ isb
+alternative_else_nop_endif
+ .endm
+
#else /* CONFIG_ARM64_PTR_AUTH */
.macro ptrauth_keys_install_user tsk, tmp1, tmp2, tmp3
.endm
+ .macro ptrauth_keys_install_kernel 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 cc42145..599dd09 100644
--- a/arch/arm64/include/asm/pointer_auth.h
+++ b/arch/arm64/include/asm/pointer_auth.h
@@ -30,6 +30,10 @@ struct ptrauth_keys_user {
struct ptrauth_key apga;
};
+struct ptrauth_keys_kernel {
+ struct ptrauth_key apia;
+};
+
static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
{
if (system_supports_address_auth()) {
@@ -43,6 +47,12 @@ static inline void ptrauth_keys_init_user(struct ptrauth_keys_user *keys)
get_random_bytes(&keys->apga, sizeof(keys->apga));
}
+static inline void ptrauth_keys_init_kernel(struct ptrauth_keys_kernel *keys)
+{
+ if (system_supports_address_auth())
+ get_random_bytes(&keys->apia, sizeof(keys->apia));
+}
+
extern int ptrauth_prctl_reset_keys(struct task_struct *tsk, unsigned long arg);
/*
@@ -59,11 +69,14 @@ static inline unsigned long ptrauth_strip_insn_pac(unsigned long ptr)
#define ptrauth_thread_init_user(tsk) \
ptrauth_keys_init_user(&(tsk)->thread.keys_user)
+#define ptrauth_thread_init_kernel(tsk) \
+ ptrauth_keys_init_kernel(&(tsk)->thread.keys_kernel)
#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_init_kernel(tsk)
#endif /* CONFIG_ARM64_PTR_AUTH */
#endif /* __ASM_POINTER_AUTH_H */
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 8ec792d..c12c98d 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -145,6 +145,7 @@ struct thread_struct {
struct debug_info debug; /* debugging */
#ifdef CONFIG_ARM64_PTR_AUTH
struct ptrauth_keys_user keys_user;
+ struct ptrauth_keys_kernel keys_kernel;
#endif
};
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index ddb6d70..8664ec4 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -36,6 +36,7 @@
#include <linux/threads.h>
#include <linux/cpumask.h>
#include <linux/thread_info.h>
+#include <asm/pointer_auth.h>
DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
@@ -93,6 +94,9 @@ asmlinkage void secondary_start_kernel(void);
struct secondary_data {
void *stack;
struct task_struct *task;
+#ifdef CONFIG_ARM64_PTR_AUTH
+ struct ptrauth_keys_kernel ptrauth_key;
+#endif
long status;
};
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index cf15182..7e0e1bc 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -42,6 +42,7 @@ int main(void)
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));
+ DEFINE(THREAD_KEYS_KERNEL, offsetof(struct task_struct, thread.keys_kernel));
#endif
BLANK();
DEFINE(S_X0, offsetof(struct pt_regs, regs[0]));
@@ -90,6 +91,9 @@ int main(void)
BLANK();
DEFINE(CPU_BOOT_STACK, offsetof(struct secondary_data, stack));
DEFINE(CPU_BOOT_TASK, offsetof(struct secondary_data, task));
+#ifdef CONFIG_ARM64_PTR_AUTH
+ DEFINE(CPU_BOOT_PTRAUTH_KEY, offsetof(struct secondary_data, ptrauth_key));
+#endif
BLANK();
#ifdef CONFIG_KVM_ARM_HOST
DEFINE(VCPU_CONTEXT, offsetof(struct kvm_vcpu, arch.ctxt));
@@ -136,6 +140,7 @@ int main(void)
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));
+ DEFINE(PTRAUTH_KERNEL_KEY_APIA, offsetof(struct ptrauth_keys_kernel, apia));
BLANK();
#endif
return 0;
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 6a4e402..b85695c 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -173,6 +173,7 @@ alternative_cb_end
apply_ssbd 1, x22, x23
+ ptrauth_keys_install_kernel tsk, x20, x22, x23
.else
add x21, sp, #S_FRAME_SIZE
get_current_task tsk
@@ -342,6 +343,7 @@ alternative_else_nop_endif
msr cntkctl_el1, x1
4:
#endif
+ /* No kernel C function calls after this as user keys are set. */
ptrauth_keys_install_user tsk, x0, x1, x2
apply_ssbd 0, x0, x1
@@ -1158,6 +1160,7 @@ ENTRY(cpu_switch_to)
ldr lr, [x8]
mov sp, x9
msr sp_el0, x1
+ ptrauth_keys_install_kernel x1, x8, x9, x10
ret
ENDPROC(cpu_switch_to)
NOKPROBE(cpu_switch_to)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 3716528..0d4a3b8 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -376,6 +376,8 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
*/
fpsimd_flush_task_state(p);
+ ptrauth_thread_init_kernel(p);
+
if (likely(!(p->flags & PF_KTHREAD))) {
*childregs = *current_pt_regs();
childregs->regs[0] = 0;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index a6a5f24..b171237 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -110,6 +110,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
*/
secondary_data.task = idle;
secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;
+#if defined(CONFIG_ARM64_PTR_AUTH)
+ secondary_data.ptrauth_key.apia.lo = idle->thread.keys_kernel.apia.lo;
+ secondary_data.ptrauth_key.apia.hi = idle->thread.keys_kernel.apia.hi;
+#endif
update_cpu_boot_status(CPU_MMU_OFF);
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
@@ -136,6 +140,10 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
secondary_data.task = NULL;
secondary_data.stack = NULL;
+#if defined(CONFIG_ARM64_PTR_AUTH)
+ secondary_data.ptrauth_key.apia.lo = 0;
+ secondary_data.ptrauth_key.apia.hi = 0;
+#endif
__flush_dcache_area(&secondary_data, sizeof(secondary_data));
status = READ_ONCE(secondary_data.status);
if (ret && status) {
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 8734d99..c5a43ac 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -491,6 +491,11 @@ ENTRY(__cpu_setup)
ubfx x2, x2, #ID_AA64ISAR1_APA_SHIFT, #8
cbz x2, 3f
+ /*
+ * TODO: The primary cpu keys are reset here and may be
+ * re-initialised with values passed from bootloader or
+ * some other way.
+ */
msr_s SYS_APIAKEYLO_EL1, xzr
msr_s SYS_APIAKEYHI_EL1, xzr
@@ -503,6 +508,14 @@ alternative_if_not ARM64_HAS_ADDRESS_AUTH
b 3f
alternative_else_nop_endif
+ /* Install ptrauth key for secondary cpus */
+ adr_l x2, secondary_data
+ ldr x3, [x2, #CPU_BOOT_TASK] // get secondary_data.task
+ cbz x3, 2f // check for slow booting cpus
+ ldp x3, x4, [x2, #CPU_BOOT_PTRAUTH_KEY]
+ msr_s SYS_APIAKEYLO_EL1, x3
+ msr_s SYS_APIAKEYHI_EL1, x4
+
2: /* Enable ptrauth instructions */
ldr x2, =SCTLR_ELx_ENIA | SCTLR_ELx_ENIB | \
SCTLR_ELx_ENDA | SCTLR_ELx_ENDB
--
2.7.4
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next prev parent reply other threads:[~2019-11-19 12:35 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 12:32 [PATCH v2 00/14] arm64: return address signing Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 01/14] arm64: cpufeature: add pointer auth meta-capabilities Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 02/14] arm64: install user ptrauth keys at kernel exit time Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 03/14] arm64: create macro to park cpu in an infinite loop Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 04/14] arm64: ptrauth: Add bootup/runtime flags for __cpu_setup Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 05/14] arm64: enable ptrauth earlier Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 06/14] arm64: rename ptrauth key structures to be user-specific Amit Daniel Kachhap
2019-11-22 13:28 ` Ard Biesheuvel
2019-11-25 9:22 ` Amit Kachhap
2019-11-19 12:32 ` Amit Daniel Kachhap [this message]
2019-11-22 19:19 ` [PATCH v2 07/14] arm64: initialize and switch ptrauth kernel keys Richard Henderson
2019-11-25 9:34 ` Amit Kachhap
2019-11-25 9:39 ` Ard Biesheuvel
2019-11-25 11:01 ` Amit Kachhap
2019-11-19 12:32 ` [PATCH v2 08/14] arm64: mask PAC bits of __builtin_return_address Amit Daniel Kachhap
2019-11-21 17:42 ` Ard Biesheuvel
2019-11-22 8:48 ` Richard Henderson
2019-11-22 13:27 ` Ard Biesheuvel
2019-11-25 9:18 ` Amit Kachhap
2019-11-25 9:12 ` Amit Kachhap
2019-11-25 5:42 ` Amit Kachhap
2019-11-19 12:32 ` [PATCH v2 09/14] arm64: unwind: strip PAC from kernel addresses Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 10/14] arm64: __show_regs: strip PAC from lr in printk Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 11/14] arm64: suspend: restore the kernel ptrauth keys Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 12/14] arm64: kprobe: disable probe of ptrauth instruction Amit Daniel Kachhap
2019-11-19 12:32 ` [PATCH v2 13/14] arm64: compile the kernel with ptrauth return address signing Amit Daniel Kachhap
2019-11-21 15:06 ` Mark Brown
2019-11-26 7:00 ` Amit Kachhap
2019-11-25 17:35 ` Mark Brown
2019-11-19 12:32 ` [PATCH v2 14/14] lkdtm: arm64: test kernel pointer authentication Amit Daniel Kachhap
2019-11-21 17:39 ` Ard Biesheuvel
2019-11-22 18:51 ` Richard Henderson
2019-11-25 9:25 ` Amit Kachhap
2019-11-25 5:34 ` Amit Kachhap
2019-11-20 16:05 ` [PATCH v2 00/14] arm64: return address signing Ard Biesheuvel
2019-11-21 12:15 ` Amit Kachhap
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