From patchwork Tue Oct 23 17:55:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jessica Yu X-Patchwork-Id: 10653455 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9923414BB for ; Tue, 23 Oct 2018 17:56:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7EE252A11D for ; Tue, 23 Oct 2018 17:56:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 72B042A12A; Tue, 23 Oct 2018 17:56:30 +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=-2.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E94DC2A123 for ; Tue, 23 Oct 2018 17:56:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=xsAjiTn9Y3G/sjnmWLSfwV7hrh9lhQVFE9C3grBx5SA=; b=SkcptAGu91J3joQ6wA0BEyVhM h+83nI5h245NO23rYKE9M6dFBu2ze/pLVNqm70fwXBs7u9x1rJvdpILjGgvrSuMjVuvxP0UpV+TGm TcVRTpVUfkvFo1dg5MB53U/kHGbOJjNCV9ZE63wEYxCopZ0vItyBScA7uY2cZa0O4Kvs8cYyAi/nD 77nFVGkNWQdPbrQdUe+wrsUVixYjZD1/kz70bvxZde4jc/Bm+wPfQrJkNuTunpAejL7pLFcKLCuNn jgJkIb//s3svaLc0Bxd/3T9h3dN3xSlw5+lq8zdCefFn+iwOYxW+JD9QyuQtOhvT/W68bGjT9RHKP VyxsoD+AQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gF0ud-0003n7-R7; Tue, 23 Oct 2018 17:56:15 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gF0uZ-0003m9-Nc for linux-arm-kernel@lists.infradead.org; Tue, 23 Oct 2018 17:56:13 +0000 Received: from linux-8ccs (ip5f5adbed.dynamic.kabel-deutschland.de [95.90.219.237]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BC1A220671; Tue, 23 Oct 2018 17:55:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540317360; bh=4koekTgFWekm4QlxCRSqWdypR4TDpZwhZLdmSfFRLqs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1KeK6CZ/ReHE2QTotz5oKGvmlQcb0mBOiqyyYDV32A0g9VRqrVBjr6x6KvpZAWF41 PSWrVRV77V1wFHZ0lSuWgcKowkcgNonGpNVyELsk2+iL7ndD6/E/ca4494WxqxE+T2 +wkuSU4hQtH7kbCCt8P8J3BujCW9idEJJX5A0yWU= Date: Tue, 23 Oct 2018 19:55:54 +0200 From: Jessica Yu To: Torsten Duwe Subject: [PATCH] arm64/module: use mod->klp_info section header information Message-ID: <20181023175553.gaobskk26koft6s2@linux-8ccs> References: <20181001140910.086E768BC7@newverein.lst.de> <20181001141652.5478C68BE1@newverein.lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181001141652.5478C68BE1@newverein.lst.de> X-OS: Linux linux-8ccs 4.12.14-lp150.12.16-default x86_64 User-Agent: NeoMutt/20170912 (1.9.0) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181023_105611_803911_0533CABC X-CRM114-Status: GOOD ( 17.80 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Arnd Bergmann , Julien Thierry , Catalin Marinas , Ard Biesheuvel , Will Deacon , linux-kernel@vger.kernel.org, Steven Rostedt , AKASHI Takahiro , Ingo Molnar , Josh Poimboeuf , live-patching@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP The arm64 module loader keeps a pointer into info->sechdrs to keep track of section header information for .plt section(s). A pointer to the relevent section header (struct elf64_shdr) in info->sechdrs is stored in mod->arch.{init,core}.plt. This pointer may be accessed while applying relocations in apply_relocate_add() for example. And unlike normal modules, livepatch modules can call apply_relocate_add() after module load. But the info struct (and therefore info->sechdrs) gets freed at the end of load_module() and so mod->arch.{init,core}.plt becomes an invalid pointer after the module is done loading. Luckily, livepatch modules already keep a copy of Elf section header information in mod->klp_info. So make sure livepatch modules on arm64 have access to the section headers in klp_info and set mod->arch.{init,core}.plt to the appropriate section header in mod->klp_info so that they can call apply_relocate_add() even after module load. Signed-off-by: Jessica Yu --- Hi! This patch may be applied on top or merged with the 3rd patch. I incoporated Miroslav's suggestions from the discussion. It's needed in order for livepatch modules on arm64 to be able to call apply_relocate_add() post-module-load, otherwise we could end up accessing invalid pointers from apply_relocate_add(). arch/arm64/include/asm/module.h | 1 + arch/arm64/kernel/module-plts.c | 10 ++++++++-- arch/arm64/kernel/module.c | 10 ++++++++++ kernel/module.c | 22 +++++++++++++--------- 4 files changed, 32 insertions(+), 11 deletions(-) diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index fef773c94e9d..ac9b97f9ae5e 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -25,6 +25,7 @@ struct mod_plt_sec { struct elf64_shdr *plt; int plt_num_entries; int plt_max_entries; + int plt_shndx; }; struct mod_arch_specific { diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index f0690c2ca3e0..05067717dfc5 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -210,9 +210,15 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, * entries. Record the symtab address as well. */ for (i = 0; i < ehdr->e_shnum; i++) { - if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) + if (!strcmp(secstrings + sechdrs[i].sh_name, ".plt")) { mod->arch.core.plt = sechdrs + i; - else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) + /* + * Keep the section index for the .plt section for + * livepatching. Note that .init.plt is irrelevant to + * livepatch, so only the shndx for .plt is saved. + */ + mod->arch.core.plt_shndx = i; + } else if (!strcmp(secstrings + sechdrs[i].sh_name, ".init.plt")) mod->arch.init.plt = sechdrs + i; else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && !strcmp(secstrings + sechdrs[i].sh_name, diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index dd23655fda3a..490e56070a7e 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -461,5 +461,15 @@ int module_finalize(const Elf_Ehdr *hdr, #endif } +#ifdef CONFIG_LIVEPATCH + /* + * For livepatching, switch to the saved section header info for .plt + * stored in mod->klp_info. This is needed so that livepatch is able to + * call apply_relocate_add() after patch module load. + */ + if (is_livepatch_module(me)) + me->arch.core.plt = me->klp_info->sechdrs + me->arch.core.plt_shndx; +#endif + return 0; } diff --git a/kernel/module.c b/kernel/module.c index f475f30eed8c..f3ac04cc9fc3 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3367,6 +3367,8 @@ int __weak module_finalize(const Elf_Ehdr *hdr, static int post_relocation(struct module *mod, const struct load_info *info) { + int err; + /* Sort exception table now relocations are done. */ sort_extable(mod->extable, mod->extable + mod->num_exentries); @@ -3377,8 +3379,18 @@ static int post_relocation(struct module *mod, const struct load_info *info) /* Setup kallsyms-specific fields. */ add_kallsyms(mod, info); + if (is_livepatch_module(mod)) { + err = copy_module_elf(mod, info); + if (err < 0) + return err; + } + /* Arch-specific module finalizing. */ - return module_finalize(info->hdr, info->sechdrs, mod); + err = module_finalize(info->hdr, info->sechdrs, mod); + if (err < 0) + free_module_elf(mod); + + return err; } /* Is this module of this name done loading? No locks held. */ @@ -3770,12 +3782,6 @@ static int load_module(struct load_info *info, const char __user *uargs, if (err < 0) goto coming_cleanup; - if (is_livepatch_module(mod)) { - err = copy_module_elf(mod, info); - if (err < 0) - goto sysfs_cleanup; - } - /* Get rid of temporary copy. */ free_copy(info); @@ -3784,8 +3790,6 @@ static int load_module(struct load_info *info, const char __user *uargs, return do_init_module(mod); - sysfs_cleanup: - mod_sysfs_teardown(mod); coming_cleanup: mod->state = MODULE_STATE_GOING; destroy_params(mod->kp, mod->num_kp);