From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 71B43C46475 for ; Tue, 23 Oct 2018 17:56:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0F0402081B for ; Tue, 23 Oct 2018 17:56:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1KeK6CZ/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0F0402081B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728665AbeJXCU0 (ORCPT ); Tue, 23 Oct 2018 22:20:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:57246 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727264AbeJXCU0 (ORCPT ); Tue, 23 Oct 2018 22:20:26 -0400 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 Cc: Will Deacon , Catalin Marinas , Julien Thierry , Steven Rostedt , Josh Poimboeuf , Ingo Molnar , Ard Biesheuvel , Arnd Bergmann , AKASHI Takahiro , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org 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-Type: text/plain; charset=us-ascii; format=flowed 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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); -- 2.16.4