From patchwork Wed Aug 13 17:06:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 4720201 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 156809F377 for ; Wed, 13 Aug 2014 17:11:35 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AEF09201DC for ; Wed, 13 Aug 2014 17:11:33 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A3D8A201BF for ; Wed, 13 Aug 2014 17:11:32 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XHc3Y-0003so-CY; Wed, 13 Aug 2014 17:09:48 +0000 Received: from smtp.outflux.net ([2001:19d0:2:6:c0de:0:736d:7470]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XHc3A-00038G-KH for linux-arm-kernel@lists.infradead.org; Wed, 13 Aug 2014 17:09:25 +0000 Received: from www.outflux.net (serenity.outflux.net [10.2.0.2]) by vinyl.outflux.net (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id s7DH6eun031389; Wed, 13 Aug 2014 10:06:40 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Subject: [PATCH v4 8/8] ARM: mm: allow text and rodata sections to be read-only Date: Wed, 13 Aug 2014 10:06:33 -0700 Message-Id: <1407949593-16121-9-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407949593-16121-1-git-send-email-keescook@chromium.org> References: <1407949593-16121-1-git-send-email-keescook@chromium.org> X-MIMEDefang-Filter: outflux$Revision: 1.316 $ X-HELO: www.outflux.net X-Scanned-By: MIMEDefang 2.73 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140813_100924_725139_B556A790 X-CRM114-Status: GOOD ( 19.45 ) X-Spam-Score: -3.0 (---) Cc: Nicolas Pitre , Rob Herring , Laura Abbott , Kees Cook , Liu hua , linux-doc@vger.kernel.org, Will Deacon , Tomasz Figa , Jason Wessel , Stephen Boyd , Leif Lindholm , Doug Anderson , Rabin Vincent , Nikolay Borisov , Mark Salter , Russell King - ARM Linux , Catalin Marinas , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata read-only. Additionally, this splits rodata from text so that rodata can also be NX, which may lead to wasted memory when aligning to SECTION_SIZE. The read-only areas are made writable during ftrace updates and kexec. Signed-off-by: Kees Cook Tested-by: Laura Abbott --- arch/arm/include/asm/cacheflush.h | 10 ++++++++ arch/arm/kernel/ftrace.c | 19 ++++++++++++++++ arch/arm/kernel/machine_kexec.c | 1 + arch/arm/kernel/vmlinux.lds.S | 3 +++ arch/arm/mm/Kconfig | 12 ++++++++++ arch/arm/mm/init.c | 48 ++++++++++++++++++++++++++++++++++++++- 6 files changed, 92 insertions(+), 1 deletion(-) diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index fd43f7f55b70..0cdf1e31df86 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -487,6 +487,16 @@ int set_memory_rw(unsigned long addr, int numpages); int set_memory_x(unsigned long addr, int numpages); int set_memory_nx(unsigned long addr, int numpages); +#ifdef CONFIG_DEBUG_RODATA +void mark_rodata_ro(void); +void set_kernel_text_rw(void); +void set_kernel_text_ro(void); +#else +static inline void set_kernel_text_rw(void) { } +static inline void set_kernel_text_ro(void) { } +#endif + void flush_uprobe_xol_access(struct page *page, unsigned long uaddr, void *kaddr, unsigned long len); + #endif diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index af9a8a927a4e..b8c75e45a950 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -35,6 +36,22 @@ #define OLD_NOP 0xe1a00000 /* mov r0, r0 */ +static int __ftrace_modify_code(void *data) +{ + int *command = data; + + set_kernel_text_rw(); + ftrace_modify_all_code(*command); + set_kernel_text_ro(); + + return 0; +} + +void arch_ftrace_update_code(int command) +{ + stop_machine(__ftrace_modify_code, &command, NULL); +} + static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) { return rec->arch.old_mcount ? OLD_NOP : NOP; @@ -73,6 +90,8 @@ int ftrace_arch_code_modify_prepare(void) int ftrace_arch_code_modify_post_process(void) { set_all_modules_text_ro(); + /* Make sure any TLB misses during machine stop are cleared. */ + flush_tlb_all(); return 0; } diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8f75250cbe30..4423a565ef6f 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -164,6 +164,7 @@ void machine_kexec(struct kimage *image) reboot_code_buffer = page_address(image->control_code_page); /* Prepare parameters for reboot_code_buffer*/ + set_kernel_text_rw(); kexec_start_address = image->start; kexec_indirection_page = page_list; kexec_mach_type = machine_arch_type; diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index a3d07ca2bbb4..542e58919bd9 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -120,6 +120,9 @@ SECTIONS ARM_CPU_KEEP(PROC_INFO) } +#ifdef CONFIG_DEBUG_RODATA + . = ALIGN(1<