From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1091FC433DF for ; Thu, 9 Jul 2020 07:29:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF7DB2076A for ; Thu, 9 Jul 2020 07:29:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594279762; bh=sYXGN+ISBs9KPOjbyjpY1q+N4IQd2AK8zDLRacqq5qI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UzBx7zOdl3ndV/1eLUR0filigF/qI3XuGOjxbSvhrNVPABkqdae2Ve6/rFuaw6SST z3rPmJhICysPQnhDDcMuETAN1U4tUM3aNWYX02+NAuYyYXlPDwJnanqZdUMV9fcF8E cPSECajrpgMlARlJcblJwrJRkyaDozlwLxWZ+938= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726645AbgGIH3V (ORCPT ); Thu, 9 Jul 2020 03:29:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:42684 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726624AbgGIH3S (ORCPT ); Thu, 9 Jul 2020 03:29:18 -0400 Received: from localhost.localdomain (unknown [42.120.72.66]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 024492076A; Thu, 9 Jul 2020 07:29:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594279757; bh=sYXGN+ISBs9KPOjbyjpY1q+N4IQd2AK8zDLRacqq5qI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eSI/Rgh1kXZ1HlARWCrzTjim05pipMNwMfy1Uo8UBaJtpTBEOuNgOgMv0T/c2e8PC nCT+cTy8jHaW6SoOUhOnfVQANfKhtZSe0FcLV0aCl4oq4PoZ/Dp5jFoUHM2k9QqkUV 0/9Xapw2ikat2PVTqylpEqAUOnFvvj71N5xMTJ5I= From: guoren@kernel.org To: palmerdabbelt@google.com, paul.walmsley@sifive.com, anup@brainfault.org, greentime.hu@sifive.com, zong.li@sifive.com, me@packi.ch, bjorn.topel@gmail.com, atish.patra@wdc.com Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, guoren@kernel.org, Guo Ren , cooper , Kees Cook Subject: [PATCH v2 2/2] riscv: Enable per-task stack canaries Date: Thu, 9 Jul 2020 07:28:17 +0000 Message-Id: <1594279697-72511-2-git-send-email-guoren@kernel.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1594279697-72511-1-git-send-email-guoren@kernel.org> References: <1594279697-72511-1-git-send-email-guoren@kernel.org> Sender: linux-csky-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org From: Guo Ren This enables the use of per-task stack canary values if GCC has support for emitting the stack canary reference relative to the value of tp, which holds the task struct pointer in the riscv kernel. After compare arm64 and x86 implementations, seems arm64's is more flexible and readable. The key point is how gcc get the offset of stack_canary from gs/el0_sp. x86: Use a fix offset from gs, not flexible. struct fixed_percpu_data { /* * GCC hardcodes the stack canary as %gs:40. Since the * irq_stack is the object at %gs:0, we reserve the bottom * 48 bytes of the irq stack for the canary. */ char gs_base[40]; // :( unsigned long stack_canary; }; arm64: Use -mstack-protector-guard-offset & guard-reg gcc options: -mstack-protector-guard=sysreg -mstack-protector-guard-reg=sp_el0 -mstack-protector-guard-offset=xxx riscv: Use -mstack-protector-guard-offset & guard-reg gcc options: -mstack-protector-guard=tls -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=xxx Here is riscv gcc's work [1]. [1] https://gcc.gnu.org/pipermail/gcc-patches/2020-July/549583.html In the end, these codes are inserted by gcc before return: * 0xffffffe00020b396 <+120>: ld a5,1008(tp) # 0x3f0 * 0xffffffe00020b39a <+124>: xor a5,a5,a4 * 0xffffffe00020b39c <+126>: mv a0,s5 * 0xffffffe00020b39e <+128>: bnez a5,0xffffffe00020b61c <_do_fork+766> 0xffffffe00020b3a2 <+132>: ld ra,136(sp) 0xffffffe00020b3a4 <+134>: ld s0,128(sp) 0xffffffe00020b3a6 <+136>: ld s1,120(sp) 0xffffffe00020b3a8 <+138>: ld s2,112(sp) 0xffffffe00020b3aa <+140>: ld s3,104(sp) 0xffffffe00020b3ac <+142>: ld s4,96(sp) 0xffffffe00020b3ae <+144>: ld s5,88(sp) 0xffffffe00020b3b0 <+146>: ld s6,80(sp) 0xffffffe00020b3b2 <+148>: ld s7,72(sp) 0xffffffe00020b3b4 <+150>: addi sp,sp,144 0xffffffe00020b3b6 <+152>: ret ... * 0xffffffe00020b61c <+766>: auipc ra,0x7f8 * 0xffffffe00020b620 <+770>: jalr -1764(ra) # 0xffffffe000a02f38 <__stack_chk_fail> Signed-off-by: Guo Ren Signed-off-by: cooper Cc: cooper Cc: Kees Cook --- Change v2: - Change to -mstack-protector-guard=tls for gcc final define - Solve compile error by changing position of KBUILD_CFLAGS in Makefile Signed-off-by: Guo Ren --- arch/riscv/Kconfig | 7 +++++++ arch/riscv/Makefile | 10 ++++++++++ arch/riscv/include/asm/stackprotector.h | 3 ++- arch/riscv/kernel/asm-offsets.c | 3 +++ arch/riscv/kernel/process.c | 2 +- 5 files changed, 23 insertions(+), 2 deletions(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 4b0e308..d98ce29 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -394,6 +394,13 @@ config CMDLINE_FORCE endchoice +config CC_HAVE_STACKPROTECTOR_TLS + def_bool $(cc-option,-mstack-protector-guard=tls -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=0) + +config STACKPROTECTOR_PER_TASK + def_bool y + depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_TLS + endmenu config BUILTIN_DTB diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index fb6e37d..f5f8ee9 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -68,6 +68,16 @@ KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax) # architectures. It's faster to have GCC emit only aligned accesses. KBUILD_CFLAGS += $(call cc-option,-mstrict-align) +ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) +prepare: stack_protector_prepare +stack_protector_prepare: prepare0 + $(eval KBUILD_CFLAGS += -mstack-protector-guard=tls \ + -mstack-protector-guard-reg=tp \ + -mstack-protector-guard-offset=$(shell \ + awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \ + include/generated/asm-offsets.h)) +endif + # arch specific predefines for sparse CHECKFLAGS += -D__riscv -D__riscv_xlen=$(BITS) diff --git a/arch/riscv/include/asm/stackprotector.h b/arch/riscv/include/asm/stackprotector.h index 8e1ef2c..bda4d83 100644 --- a/arch/riscv/include/asm/stackprotector.h +++ b/arch/riscv/include/asm/stackprotector.h @@ -28,6 +28,7 @@ static __always_inline void boot_init_stack_canary(void) canary &= CANARY_MASK; current->stack_canary = canary; - __stack_chk_guard = current->stack_canary; + if (!IS_ENABLED(CONFIG_STACKPROTECTOR_PER_TASK)) + __stack_chk_guard = current->stack_canary; } #endif /* _ASM_RISCV_STACKPROTECTOR_H */ diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c index 07cb9c1..999b465 100644 --- a/arch/riscv/kernel/asm-offsets.c +++ b/arch/riscv/kernel/asm-offsets.c @@ -29,6 +29,9 @@ void asm_offsets(void) OFFSET(TASK_THREAD_S11, task_struct, thread.s[11]); OFFSET(TASK_THREAD_SP, task_struct, thread.sp); OFFSET(TASK_STACK, task_struct, stack); +#ifdef CONFIG_STACKPROTECTOR + OFFSET(TSK_STACK_CANARY, task_struct, stack_canary); +#endif OFFSET(TASK_TI, task_struct, thread_info); OFFSET(TASK_TI_FLAGS, task_struct, thread_info.flags); OFFSET(TASK_TI_PREEMPT_COUNT, task_struct, thread_info.preempt_count); diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index 6548929..cb4ac65 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -24,7 +24,7 @@ register unsigned long gp_in_global __asm__("gp"); -#ifdef CONFIG_STACKPROTECTOR +#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) #include unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); -- 2.7.4