From patchwork Mon Jun 25 22:39:13 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Garnier X-Patchwork-Id: 10488317 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C3430602B3 for ; Tue, 26 Jun 2018 08:47:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B0190287E5 for ; Tue, 26 Jun 2018 08:47:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A4A0C287E8; Tue, 26 Jun 2018 08:47:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED, USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 6E6DA287E5 for ; Tue, 26 Jun 2018 08:47:09 +0000 (UTC) Received: (qmail 30418 invoked by uid 550); 26 Jun 2018 08:40:19 -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 Delivered-To: moderator for kernel-hardening@lists.openwall.com Received: (qmail 13543 invoked from network); 25 Jun 2018 22:42:58 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:date:in-reply-to:message-id:references:subject:from:to :cc; bh=0Et0L1WNV93Y8jFq/slU2S2/QDsQt375W8lPWTfs1Bc=; b=ZitlR5a23umamAsH5LxOO1jXh5eil0uclaGl3j21u1ZcICqEwMHGHYW/SlANufZ9Pp aCrtpNfvYL8Ns4ofggvwpUFXljxxb+ZeM2tAnXx/c9zAc2a7agGqI0jitk/oQKzKyQ/3 g7vQ2161rrwm8OIFWbXgJOzIDxBeLaIo98KgABGW2ZO0pLDjxGks/fb1y/S6DWRADGNV i2xeWgrwN+fLvxx2cqpo+fJkVLHuPxxlkYCTwBwlpxsgclbdckSBSxeQ8KxC8jbulU6c 5pP96d9OSSNO0AOHt+PXiuGrlo9mFOBiLeON4iUJEkglKc8JqeDiWMQ7WH/CZ+KKLtFG SXVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:in-reply-to:message-id :references:subject:from:to:cc; bh=0Et0L1WNV93Y8jFq/slU2S2/QDsQt375W8lPWTfs1Bc=; b=GGFT2YyhJNkeFytX0IABc/eJMTYQp4//keDSad0I/802n81Me4KVuvC2aMQU3/iTBV wo3JY3SbR/8lpKP1rbggoSOURrOXGEQaIqlUY0Iyt/it9X+njm1Onmg8DnSmLbsRdAJ/ w44G4ySIruVJhF2drTYmA6inm5dghIhqCKkjLGsN3PmhCS//C5k/u2eNK87S60eLZ0Mf CpkC4paVywyhoX6Xk6wIIwM/Mcwg5/32XJw4fROjeYJHx37eWiDxUNfnyroEBjBtyu5L X0ZQWe8Cx6JZ1jCN2e2M7arYLypp4v6q4hM26YRLBUj9EbaZpyb1fSbRcjCQl7QU/aIK Hh6w== X-Gm-Message-State: APt69E0+fa9xtg1wrgrcRc6XoXcMEPd3xchkeTUKa4foCyZu6EU5Fmr5 AkWgMuQ3VaOqDA3Nw/ExYzGl7agyBsJceSr1ZtyJj4vBbyFOkrBC56aXFIFatDj4tFIcmNr9Uki JaahZRcs439T6KH5mH/x7MauyZlV8Wf5hvMDSSncw5JYOQleMMXOx11K6C8VFXSSL/OL1AyCUVB X7Py1z2ahj X-Google-Smtp-Source: ADUXVKLjl5yCkiFySSReJU+4bOqmO0dc7PlRxQcx3A4TQQPoNoLAeQQHI7UE7Rs9Uu5jlbaA+iVg6nT6XWoYPw== MIME-Version: 1.0 X-Received: by 2002:a1f:ae0a:: with SMTP id x10-v6mr6560226vke.92.1529966566293; Mon, 25 Jun 2018 15:42:46 -0700 (PDT) Date: Mon, 25 Jun 2018 15:39:13 -0700 In-Reply-To: <20180625224014.134829-1-thgarnie@google.com> Message-Id: <20180625224014.134829-26-thgarnie@google.com> References: <20180625224014.134829-1-thgarnie@google.com> X-Mailer: git-send-email 2.18.0.rc2.346.g013aa6912e-goog Subject: [PATCH v5 25/27] x86/pie: Add option to build the kernel as PIE From: Thomas Garnier To: kernel-hardening@lists.openwall.com Cc: Thomas Garnier , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add the CONFIG_X86_PIE option which builds the kernel as a Position Independent Executable (PIE). The kernel is currently build with the mcmodel=kernel option which forces it to stay on the top 2G of the virtual address space. With PIE, the kernel will be able to move below the current limit. The --emit-relocs linker option was kept instead of using -pie to limit the impact on mapped sections. Any incompatible relocation will be catch by the arch/x86/tools/relocs binary at compile time. If segment based stack cookies are enabled, try to use the compiler option to select the segment register. If not available, automatically enabled global stack cookie in auto mode. Otherwise, recommend compiler update or global stack cookie option. Performance/Size impact: Size of vmlinux (Default configuration): File size: - PIE disabled: +0.18% - PIE enabled: -1.977% (less relocations) .text section: - PIE disabled: same - PIE enabled: same Size of vmlinux (Ubuntu configuration): File size: - PIE disabled: +0.21% - PIE enabled: +10% .text section: - PIE disabled: same - PIE enabled: +0.001% The size increase is mainly due to not having access to the 32-bit signed relocation that can be used with mcmodel=kernel. A small part is due to reduced optimization for PIE code. This bug [1] was opened with gcc to provide a better code generation for kernel PIE. Hackbench (50% and 1600% on thread/process for pipe/sockets): - PIE disabled: no significant change (avg -/+ 0.5% on latest test). - PIE enabled: between -1% to +1% in average (default and Ubuntu config). Kernbench (average of 10 Half and Optimal runs): Elapsed Time: - PIE disabled: no significant change (avg -0.5%) - PIE enabled: average -0.5% to +0.5% System Time: - PIE disabled: no significant change (avg -0.1%) - PIE enabled: average -0.4% to +0.4%. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82303 Signed-off-by: Thomas Garnier merge pie --- arch/x86/Kconfig | 8 ++++++++ arch/x86/Makefile | 45 ++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 52 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f98a47662023..42f77aff5df1 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -2228,6 +2228,14 @@ config X86_GLOBAL_STACKPROTECTOR If unsure, say N +config X86_PIE + bool + depends on X86_64 + select DEFAULT_HIDDEN + select WEAK_PROVIDE_HIDDEN + select DYNAMIC_MODULE_BASE + select MODULE_REL_CRCS if MODVERSIONS + config HOTPLUG_CPU bool "Support for hot-pluggable CPUs" depends on SMP diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 112ccdc99566..b3647d78c26e 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -60,6 +60,8 @@ endif KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow KBUILD_CFLAGS += $(call cc-option,-mno-avx,) +stackglobal := $(call cc-option-yn, -mstack-protector-guard=global) + ifeq ($(CONFIG_X86_32),y) BITS := 32 UTS_MACHINE := i386 @@ -135,7 +137,48 @@ else KBUILD_CFLAGS += -mno-red-zone ifdef CONFIG_X86_PIE + KBUILD_CFLAGS += -fPIE KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/x86/kernel/module.lds + + # Relax relocation in both CFLAGS and LDFLAGS to support older compilers + KBUILD_CFLAGS += $(call cc-option,-Wa$(comma)-mrelax-relocations=no) + LDFLAGS_vmlinux += $(call ld-option,--no-relax) + KBUILD_LDFLAGS_MODULE += $(call ld-option,--no-relax) + + # Stack validation is not yet support due to self-referenced switches +ifdef CONFIG_STACK_VALIDATION + $(warning CONFIG_STACK_VALIDATION is not yet supported for x86_64 pie \ + build.) + SKIP_STACK_VALIDATION := 1 + export SKIP_STACK_VALIDATION +endif + +ifndef CONFIG_CC_STACKPROTECTOR_NONE +ifndef CONFIG_X86_GLOBAL_STACKPROTECTOR + stackseg-flag := -mstack-protector-guard-reg=%gs + ifeq ($(call cc-option-yn,$(stackseg-flag)),n) + # Try to enable global stack cookie if possible + ifeq ($(stackglobal), y) + $(warning Cannot use CONFIG_CC_STACKPROTECTOR_* while \ + building a position independent kernel. \ + Default to global stack protector \ + (CONFIG_X86_GLOBAL_STACKPROTECTOR).) + CONFIG_X86_GLOBAL_STACKPROTECTOR := y + KBUILD_CFLAGS += -DCONFIG_X86_GLOBAL_STACKPROTECTOR + KBUILD_AFLAGS += -DCONFIG_X86_GLOBAL_STACKPROTECTOR + else + $(error echo Cannot use \ + CONFIG_CC_STACKPROTECTOR_(REGULAR|STRONG|AUTO) \ + while building a position independent binary. \ + Update your compiler or use \ + CONFIG_X86_GLOBAL_STACKPROTECTOR) + endif + else + KBUILD_CFLAGS += $(stackseg-flag) + endif +endif +endif + else KBUILD_CFLAGS += -mcmodel=kernel endif @@ -146,7 +189,7 @@ endif endif ifdef CONFIG_X86_GLOBAL_STACKPROTECTOR - ifeq ($(call cc-option, -mstack-protector-guard=global),) + ifeq ($(stackglobal), n) $(error Cannot use CONFIG_X86_GLOBAL_STACKPROTECTOR: \ -mstack-protector-guard=global not supported \ by compiler)