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=-15.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 9A3B6C433E0 for ; Sun, 5 Jul 2020 14:15:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B25820739 for ; Sun, 5 Jul 2020 14:15:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593958514; bh=zNnCIpEumQvRRF67btqkikC48THjPev/mPim2NMvzSs=; h=From:To:Cc:Subject:Date:List-ID:From; b=doanMgwiEhOVryqOoaNsIsUP9x0258nFC699uECmXICvXs/IxxPpADAXdrDQ0T+kp Neub2V1EabhG9M2SSIn712GnDjutkzwmdVBUAeKQTN5ZFhYpO+0UjlscUnSlfmBvtw ds/eT6+/Y/axwTxd9SL9sHXcfl4FvOQCxAW0Rgik= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726894AbgGEOPK (ORCPT ); Sun, 5 Jul 2020 10:15:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:34504 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726538AbgGEOPK (ORCPT ); Sun, 5 Jul 2020 10:15:10 -0400 Received: from localhost.localdomain (unknown [89.208.247.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EA3BC20724; Sun, 5 Jul 2020 14:15:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593958509; bh=zNnCIpEumQvRRF67btqkikC48THjPev/mPim2NMvzSs=; h=From:To:Cc:Subject:Date:From; b=h6k1WaQYt6l4lzPM4ByGzaWTADkxgSPSiqQaUlU6QPUTlvVVWvRdPWWN713XTEuJM oZVzeKncNXDEBkdSjnL93PNQkrpqynSiSQeJr+vAlP4n5qUT6NjglOdw2o7LJ9w4Hq gOPaD1zQ88oGl/m87zZnrCjWStbrBFJBnLbkEixc= From: guoren@kernel.org To: guoren@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, Guo Ren , Kees Cook Subject: [RFC PATCH] riscv: enable per-task stack canaries Date: Sun, 5 Jul 2020 14:13:17 +0000 Message-Id: <1593958397-62466-1-git-send-email-guoren@kernel.org> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guo Ren 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 ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) prepare: stack_protector_prepare stack_protector_prepare: prepare0 $(eval KBUILD_CFLAGS += -mstack-protector-guard=sysreg \ -mstack-protector-guard-reg=sp_el0 \ -mstack-protector-guard-offset=$(shell \ awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \ include/generated/asm-offsets.h)) endif I prefer arm64, but x86 percpu_data design needs to be considered ? After the discussion, let's continue the work for riscv gcc stack-protector. Here is arm64 gcc's work [1]. [1] https://github.com/gcc-mirror/gcc/commit/cd0b2d361df82c848dc7e1c3078651bb0624c3c6 Signed-off-by: Guo Ren Cc: Kees Cook --- 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..4b4e833 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -394,6 +394,13 @@ config CMDLINE_FORCE endchoice +config CC_HAVE_STACKPROTECTOR_SYSREG + def_bool $(cc-option,-mstack-protector-guard=gpr -mstack-protector-guard-reg=tp -mstack-protector-guard-offset=0) + +config STACKPROTECTOR_PER_TASK + def_bool y + depends on STACKPROTECTOR && CC_HAVE_STACKPROTECTOR_SYSREG + endmenu config BUILTIN_DTB diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index fb6e37d..880a288 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -47,6 +47,16 @@ KBUILD_AFLAGS += -march=$(riscv-march-y) KBUILD_CFLAGS += -mno-save-restore KBUILD_CFLAGS += -DCONFIG_PAGE_OFFSET=$(CONFIG_PAGE_OFFSET) +ifeq ($(CONFIG_STACKPROTECTOR_PER_TASK),y) +prepare: stack_protector_prepare +stack_protector_prepare: prepare0 + $(eval KBUILD_CFLAGS += -mstack-protector-guard=gpr \ + -mstack-protector-guard-reg=tp \ + -mstack-protector-guard-offset=$(shell \ + awk '{if ($$2 == "TSK_STACK_CANARY") print $$3;}' \ + include/generated/asm-offsets.h)) +endif + ifeq ($(CONFIG_CMODEL_MEDLOW),y) KBUILD_CFLAGS += -mcmodel=medlow endif diff --git a/arch/riscv/include/asm/stackprotector.h b/arch/riscv/include/asm/stackprotector.h index 5962f88..09093af 100644 --- a/arch/riscv/include/asm/stackprotector.h +++ b/arch/riscv/include/asm/stackprotector.h @@ -24,6 +24,7 @@ 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