From patchwork Wed Aug 6 19:32:41 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 4688281 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id BA05CC033A for ; Wed, 6 Aug 2014 19:37:58 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DA5E820145 for ; Wed, 6 Aug 2014 19:37:56 +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 DF26A2013A for ; Wed, 6 Aug 2014 19:37:55 +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 1XF70Y-0006UB-PF; Wed, 06 Aug 2014 19:36:22 +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 1XF6zu-0005ii-C3 for linux-arm-kernel@lists.infradead.org; Wed, 06 Aug 2014 19:35:43 +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 s76JWpEI004032; Wed, 6 Aug 2014 12:32:52 -0700 From: Kees Cook To: linux-kernel@vger.kernel.org Subject: [PATCH 4/7] arm: use fixmap for text patching when text is RO Date: Wed, 6 Aug 2014 12:32:41 -0700 Message-Id: <1407353564-21478-5-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407353564-21478-1-git-send-email-keescook@chromium.org> References: <1407353564-21478-1-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-20140806_123542_475120_BEF4C7D2 X-CRM114-Status: GOOD ( 16.01 ) X-Spam-Score: -3.0 (---) Cc: Nicolas Pitre , Rob Herring , Laura Abbott , Kees Cook , Liu hua , Catalin Marinas , Tomasz Figa , Will Deacon , Leif Lindholm , Doug Anderson , Rabin Vincent , Nikolay Borisov , Mark Salter , Russell King - ARM Linux , 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,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 From: Rabin Vincent Use fixmaps for text patching when the kernel text is read-only, inspired by x86. This makes jump labels and kprobes work with the currently available CONFIG_DEBUG_SET_MODULE_RONX and the upcoming CONFIG_DEBUG_RODATA options. Signed-off-by: Rabin Vincent [update for "ARM: 8031/2: change fixmap mapping region to support 32 CPUs"] Signed-off-by: Kees Cook --- arch/arm/include/asm/fixmap.h | 4 +++ arch/arm/kernel/jump_label.c | 2 +- arch/arm/kernel/patch.c | 70 ++++++++++++++++++++++++++++++++++++++----- arch/arm/kernel/patch.h | 12 +++++++- 4 files changed, 79 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h index 3ed08232be55..056f2be273a3 100644 --- a/arch/arm/include/asm/fixmap.h +++ b/arch/arm/include/asm/fixmap.h @@ -19,6 +19,10 @@ enum fixed_addresses { FIX_KMAP_BEGIN, FIX_KMAP_END = (FIX_KMAP_NR_PTES * FIX_KMAP_NR_CPUS) - 1, + /* Support writing RO kernel text via kprobes, jump labels, etc. */ + FIX_TEXT_POKE0, + FIX_TEXT_POKE1, + __end_of_fixed_addresses }; diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c index 4ce4f789446d..afeeb9ea6f43 100644 --- a/arch/arm/kernel/jump_label.c +++ b/arch/arm/kernel/jump_label.c @@ -19,7 +19,7 @@ static void __arch_jump_label_transform(struct jump_entry *entry, insn = arm_gen_nop(); if (is_static) - __patch_text(addr, insn); + __patch_text_early(addr, insn); else patch_text(addr, insn); } diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c index 07314af47733..03dd4e39c833 100644 --- a/arch/arm/kernel/patch.c +++ b/arch/arm/kernel/patch.c @@ -1,8 +1,11 @@ #include +#include #include +#include #include #include +#include #include #include @@ -13,21 +16,69 @@ struct patch { unsigned int insn; }; -void __kprobes __patch_text(void *addr, unsigned int insn) +static DEFINE_SPINLOCK(patch_lock); + +static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) +{ + unsigned int uintaddr = (uintptr_t) addr; + bool module = !core_kernel_text(uintaddr); + struct page *page; + + if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) + page = vmalloc_to_page(addr); + else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) + page = virt_to_page(addr); + else + return addr; + + if (flags) + spin_lock_irqsave(&patch_lock, *flags); + + set_fixmap(fixmap, page_to_phys(page)); + + return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK)); +} + +static void __kprobes patch_unmap(int fixmap, unsigned long *flags) +{ + clear_fixmap(fixmap); + + if (flags) + spin_unlock_irqrestore(&patch_lock, *flags); +} + +void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap) { bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL); + unsigned int uintaddr = (uintptr_t) addr; + bool twopage = false; + unsigned long flags; + void *waddr = addr; int size; + if (remap) + waddr = patch_map(addr, FIX_TEXT_POKE0, &flags); + if (thumb2 && __opcode_is_thumb16(insn)) { - *(u16 *)addr = __opcode_to_mem_thumb16(insn); + *(u16 *)waddr = __opcode_to_mem_thumb16(insn); size = sizeof(u16); - } else if (thumb2 && ((uintptr_t)addr & 2)) { + } else if (thumb2 && (uintaddr & 2)) { u16 first = __opcode_thumb32_first(insn); u16 second = __opcode_thumb32_second(insn); - u16 *addrh = addr; + u16 *addrh0 = waddr; + u16 *addrh1 = waddr + 2; - addrh[0] = __opcode_to_mem_thumb16(first); - addrh[1] = __opcode_to_mem_thumb16(second); + twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2; + if (twopage && remap) + addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL); + + *addrh0 = __opcode_to_mem_thumb16(first); + *addrh1 = __opcode_to_mem_thumb16(second); + + if (twopage && addrh1 != addr + 2) { + flush_kernel_vmap_range(addrh1, 2); + patch_unmap(FIX_TEXT_POKE1, NULL); + } size = sizeof(u32); } else { @@ -36,10 +87,15 @@ void __kprobes __patch_text(void *addr, unsigned int insn) else insn = __opcode_to_mem_arm(insn); - *(u32 *)addr = insn; + *(u32 *)waddr = insn; size = sizeof(u32); } + if (waddr != addr) { + flush_kernel_vmap_range(waddr, twopage ? size / 2 : size); + patch_unmap(FIX_TEXT_POKE0, &flags); + } + flush_icache_range((uintptr_t)(addr), (uintptr_t)(addr) + size); } diff --git a/arch/arm/kernel/patch.h b/arch/arm/kernel/patch.h index b4731f2dac38..77e054c2f6cd 100644 --- a/arch/arm/kernel/patch.h +++ b/arch/arm/kernel/patch.h @@ -2,6 +2,16 @@ #define _ARM_KERNEL_PATCH_H void patch_text(void *addr, unsigned int insn); -void __patch_text(void *addr, unsigned int insn); +void __patch_text_real(void *addr, unsigned int insn, bool remap); + +static inline void __patch_text(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, true); +} + +static inline void __patch_text_early(void *addr, unsigned int insn) +{ + __patch_text_real(addr, insn, false); +} #endif