From patchwork Wed Sep 23 17:38:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kristen Carlson Accardi X-Patchwork-Id: 11795347 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E32B2618 for ; Wed, 23 Sep 2020 17:40:28 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4505C20B1F for ; Wed, 23 Sep 2020 17:40:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4505C20B1F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-19974-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 5610 invoked by uid 550); 23 Sep 2020 17:40:23 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 5501 invoked from network); 23 Sep 2020 17:40:22 -0000 IronPort-SDR: Dw5jrwNM+8ko+XpH9x21J2tNFSluxII/6j24uzk4wTuQyFicjMn873e2oFDT7+pPfNlVddQO0E WCJHRzP7xQ4Q== X-IronPort-AV: E=McAfee;i="6000,8403,9753"; a="222548898" X-IronPort-AV: E=Sophos;i="5.77,293,1596524400"; d="scan'208";a="222548898" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False IronPort-SDR: FE1hSON25G6Tvgbqpi7Vg0+F9ucWFU0hDup715ktVBXKfJP0FaBnXW8V5iOFFVYiHwTpjB948b jp54cm1zd7LQ== X-IronPort-AV: E=Sophos;i="5.77,293,1596524400"; d="scan'208";a="309992993" From: Kristen Carlson Accardi To: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, Masahiro Yamada , Michal Marek , x86@kernel.org, "H. Peter Anvin" , Arnd Bergmann Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, Kristen Carlson Accardi , Tony Luck , linux-kbuild@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH v5 03/10] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Date: Wed, 23 Sep 2020 10:38:57 -0700 Message-Id: <20200923173905.11219-4-kristen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200923173905.11219-1-kristen@linux.intel.com> References: <20200923173905.11219-1-kristen@linux.intel.com> MIME-Version: 1.0 Allow user to select CONFIG_FG_KASLR if dependencies are met. Change the make file to build with -ffunction-sections if CONFIG_FG_KASLR. While the only architecture that supports CONFIG_FG_KASLR does not currently enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION, make sure these 2 features play nicely together for the future by ensuring that if CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is selected when used with CONFIG_FG_KASLR the function sections will not be consolidated back into .text. Thanks to Kees Cook for the dead code elimination changes. Signed-off-by: Kristen Carlson Accardi Reviewed-by: Tony Luck Reviewed-by: Kees Cook Tested-by: Tony Luck --- Makefile | 6 +++++- arch/x86/Kconfig | 4 ++++ include/asm-generic/vmlinux.lds.h | 16 ++++++++++++++-- init/Kconfig | 14 ++++++++++++++ 4 files changed, 37 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index 2b66d3398878..0c116b833fd5 100644 --- a/Makefile +++ b/Makefile @@ -878,10 +878,14 @@ KBUILD_CFLAGS += $(call cc-option, -fno-inline-functions-called-once) endif ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION -KBUILD_CFLAGS_KERNEL += -ffunction-sections -fdata-sections +KBUILD_CFLAGS_KERNEL += -fdata-sections LDFLAGS_vmlinux += --gc-sections endif +ifneq ($(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION)$(CONFIG_FG_KASLR),) +KBUILD_CFLAGS += -ffunction-sections +endif + ifdef CONFIG_SHADOW_CALL_STACK CC_FLAGS_SCS := -fsanitize=shadow-call-stack KBUILD_CFLAGS += $(CC_FLAGS_SCS) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 7101ac64bb20..ff0f90d0421f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -374,6 +374,10 @@ config CC_HAS_SANE_STACKPROTECTOR We have to make sure stack protector is unconditionally disabled if the compiler produces broken code. +config ARCH_HAS_FG_KASLR + def_bool y + depends on RANDOMIZE_BASE && X86_64 + menu "Processor type and features" config ZONE_DMA diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 5430febd34be..afd5cdf79a3a 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -93,14 +93,12 @@ * sections to be brought in with rodata. */ #ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION -#define TEXT_MAIN .text .text.[0-9a-zA-Z_]* #define DATA_MAIN .data .data.[0-9a-zA-Z_]* .data..LPBX* #define SDATA_MAIN .sdata .sdata.[0-9a-zA-Z_]* #define RODATA_MAIN .rodata .rodata.[0-9a-zA-Z_]* #define BSS_MAIN .bss .bss.[0-9a-zA-Z_]* #define SBSS_MAIN .sbss .sbss.[0-9a-zA-Z_]* #else -#define TEXT_MAIN .text #define DATA_MAIN .data #define SDATA_MAIN .sdata #define RODATA_MAIN .rodata @@ -108,6 +106,20 @@ #define SBSS_MAIN .sbss #endif +/* + * Both LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_FG_KASLR options enable + * -ffunction-sections, which produces separately named .text sections. In + * the case of CONFIG_FG_KASLR, they need to stay distict so they can be + * separately randomized. Without CONFIG_FG_KASLR, the separate .text + * sections can be collected back into a common section, which makes the + * resulting image slightly smaller + */ +#if defined(CONFIG_LD_DEAD_CODE_DATA_ELIMINATION) && !defined(CONFIG_FG_KASLR) +#define TEXT_MAIN .text .text.[0-9a-zA-Z_]* +#else +#define TEXT_MAIN .text +#endif + /* * GCC 4.5 and later have a 32 bytes section alignment for structures. * Except GCC 4.9, that feels the need to align on 64 bytes. diff --git a/init/Kconfig b/init/Kconfig index d6a0b31b13dc..81220973b064 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -2019,6 +2019,20 @@ config PROFILING config TRACEPOINTS bool +config FG_KASLR + bool "Function Granular Kernel Address Space Layout Randomization" + depends on $(cc-option, -ffunction-sections) + depends on ARCH_HAS_FG_KASLR + default n + help + This option improves the randomness of the kernel text + over basic Kernel Address Space Layout Randomization (KASLR) + by reordering the kernel text at boot time. This feature + uses information generated at compile time to re-layout the + kernel text section at boot time at function level granularity. + + If unsure, say N. + endmenu # General setup source "arch/Kconfig"