From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C610A82886; Fri, 21 Jun 2024 02:24:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718936699; cv=none; b=Is+Nm89EMhGkiR2QOh3AkEOtEVfJTZ9EVOy3gDGalcFNtWXfbWWojIK9V8pf66bQJBLNtbsDg6+qQYbkYxtlrV4tTw/HU485RY1CtvdDff5rEFwfBYKoaRWmmiD2kHR4wfCvUX0ZVccHbKsQGSQClxrWmbBY5v6lexxZNXYz8FA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718936699; c=relaxed/simple; bh=PraBJhcoPBo5S5n6x2fO4drOmb0FI0JqOZb9NqLnUYQ=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=CpYEQ9qFKaBv+EQjn+MtKVdwbbZvQ6X5mBj3erebT7RKhUxshHtl1DyJIzeouT/Q0kuIRs6SCaEZro6tLnvqge6smOKyMJNxVldtZeHJ41JiOS9CX3icbBMtaNnVENV2gM4NHbb3o9AeaBEIK62iNili1ZStCuExvGMCNm4NlJI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.188 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.105]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4W51K90pJpzVlQc; Fri, 21 Jun 2024 10:19:57 +0800 (CST) Received: from kwepemi100008.china.huawei.com (unknown [7.221.188.57]) by mail.maildlp.com (Postfix) with ESMTPS id 157591402CF; Fri, 21 Jun 2024 10:24:54 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemi100008.china.huawei.com (7.221.188.57) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 21 Jun 2024 10:24:53 +0800 Message-ID: Date: Fri, 21 Jun 2024 10:24:52 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH] ARM: Add support for STACKLEAK gcc plugin Content-Language: en-US To: Kees Cook CC: , , , , , , , , , , , , , , , , , , , Alexander Popov References: <20240620131649.886995-1-ruanjinjie@huawei.com> <202406201136.A441E0B7@keescook> From: Jinjie Ruan In-Reply-To: <202406201136.A441E0B7@keescook> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi100008.china.huawei.com (7.221.188.57) On 2024/6/21 2:38, Kees Cook wrote: > On Thu, Jun 20, 2024 at 09:16:49PM +0800, Jinjie Ruan wrote: >> Add the STACKLEAK gcc plugin to arm32 by adding the helper used by >> stackleak common code: on_thread_stack(). It initialize the stack with the >> poison value before returning from system calls which improves the kernel >> security. Additionally, this disables the plugin in EFI stub code and >> decompress code, which are out of scope for the protection. > > Oh very cool! Thanks for sending this! > >> Before the test on Qemu versatilepb board: >> # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT >> lkdtm: Performing direct entry STACKLEAK_ERASING >> lkdtm: XFAIL: stackleak is not supported on this arch (HAVE_ARCH_STACKLEAK=n) >> >> After: >> # echo STACKLEAK_ERASING > /sys/kernel/debug/provoke-crash/DIRECT >> lkdtm: Performing direct entry STACKLEAK_ERASING >> lkdtm: stackleak stack usage: >> high offset: 80 bytes >> current: 280 bytes >> lowest: 696 bytes >> tracked: 696 bytes >> untracked: 192 bytes >> poisoned: 7220 bytes >> low offset: 4 bytes >> lkdtm: OK: the rest of the thread stack is properly erased >> >> Signed-off-by: Jinjie Ruan >> --- >> arch/arm/Kconfig | 1 + >> arch/arm/boot/compressed/Makefile | 1 + >> arch/arm/include/asm/stacktrace.h | 5 +++++ >> arch/arm/kernel/entry-common.S | 3 +++ >> drivers/firmware/efi/libstub/Makefile | 3 ++- >> 5 files changed, 12 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >> index 036381c5d42f..b211b7f5a138 100644 >> --- a/arch/arm/Kconfig >> +++ b/arch/arm/Kconfig >> @@ -86,6 +86,7 @@ config ARM >> select HAVE_ARCH_PFN_VALID >> select HAVE_ARCH_SECCOMP >> select HAVE_ARCH_SECCOMP_FILTER if AEABI && !OABI_COMPAT >> + select HAVE_ARCH_STACKLEAK >> select HAVE_ARCH_THREAD_STRUCT_WHITELIST >> select HAVE_ARCH_TRACEHOOK >> select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE >> diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile >> index 6bca03c0c7f0..945b5975fce2 100644 >> --- a/arch/arm/boot/compressed/Makefile >> +++ b/arch/arm/boot/compressed/Makefile >> @@ -9,6 +9,7 @@ OBJS = >> >> HEAD = head.o >> OBJS += misc.o decompress.o >> +CFLAGS_decompress.o += $(DISABLE_STACKLEAK_PLUGIN) >> ifeq ($(CONFIG_DEBUG_UNCOMPRESS),y) >> OBJS += debug.o >> AFLAGS_head.o += -DDEBUG >> diff --git a/arch/arm/include/asm/stacktrace.h b/arch/arm/include/asm/stacktrace.h >> index 360f0d2406bf..a9b4b72ed241 100644 >> --- a/arch/arm/include/asm/stacktrace.h >> +++ b/arch/arm/include/asm/stacktrace.h >> @@ -26,6 +26,11 @@ struct stackframe { >> #endif >> }; >> >> +static inline bool on_thread_stack(void) >> +{ >> + return !(((unsigned long)(current->stack) ^ current_stack_pointer) & ~(THREAD_SIZE - 1)); >> +} >> + >> static __always_inline >> void arm_get_current_stackframe(struct pt_regs *regs, struct stackframe *frame) >> { >> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >> index 5c31e9de7a60..f379c852dcb7 100644 >> --- a/arch/arm/kernel/entry-common.S >> +++ b/arch/arm/kernel/entry-common.S >> @@ -119,6 +119,9 @@ no_work_pending: >> >> ct_user_enter save = 0 >> >> +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK >> + bl stackleak_erase_on_task_stack >> +#endif >> restore_user_regs fast = 0, offset = 0 >> ENDPROC(ret_to_user_from_irq) >> ENDPROC(ret_to_user) >> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile >> index 06f0428a723c..20d8a491f25f 100644 >> --- a/drivers/firmware/efi/libstub/Makefile >> +++ b/drivers/firmware/efi/libstub/Makefile >> @@ -27,7 +27,8 @@ cflags-$(CONFIG_ARM64) += -fpie $(DISABLE_STACKLEAK_PLUGIN) \ >> cflags-$(CONFIG_ARM) += -DEFI_HAVE_STRLEN -DEFI_HAVE_STRNLEN \ >> -DEFI_HAVE_MEMCHR -DEFI_HAVE_STRRCHR \ >> -DEFI_HAVE_STRCMP -fno-builtin -fpic \ >> - $(call cc-option,-mno-single-pic-base) >> + $(call cc-option,-mno-single-pic-base) \ >> + $(DISABLE_STACKLEAK_PLUGIN) >> cflags-$(CONFIG_RISCV) += -fpic -DNO_ALTERNATIVE -mno-relax >> cflags-$(CONFIG_LOONGARCH) += -fpie > > This looks very straight forward! If an ARM person can Ack this, I could > carry it via the hardening tree. Otherwise, it should probably go via > rmk's patch tracker? Thank you for your attention and reply. > > -Kees >