From patchwork Fri Oct 26 17:25:01 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jessica Yu X-Patchwork-Id: 10657691 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 B534A109C for ; Fri, 26 Oct 2018 17:25:29 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8E81F2CAC8 for ; Fri, 26 Oct 2018 17:25:29 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7F25D2CB24; Fri, 26 Oct 2018 17:25:29 +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 D325E2CAC8 for ; Fri, 26 Oct 2018 17:25:28 +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=dvE5SGKvrqQGlT1zX5b4ZvZ1PbPKhcq1batWqM3rMiA=; b=Uwq9gwwmf2wsKFZumeoes1KYm 2WF+HdYvUiOzG9xUHQjieDWZRxFRrt+az2iZsDgAGarYr/DxZQATnBZe6FAPGX22DHBEXvn4qRIr2 7yDT6yooDkpSXfl+EFrR6mltCuQU8K09Rok2rvVDQGuFC95Qylx21gIFylsocc97LtGyQoZYu85Dd E8I2m+jhSpps2bJRonzGvwYFT8S1vJrTNFGKgihwvZtRaMrvaJkBmDjv3sRn8pOwZRUK1D90Dot7S VTL5SYrbMgTTk+CIoCyqJ56UuwP2ZzDUKbAIk3lChYZh0TNAgxkKyMcMSmCDefjEAIhhGBRtEBOHM YAUe1hfUA==; 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 1gG5rL-0007BM-Mj; Fri, 26 Oct 2018 17:25:19 +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 1gG5rJ-0006B3-19 for linux-arm-kernel@lists.infradead.org; Fri, 26 Oct 2018 17:25:18 +0000 Received: from linux-8ccs (ip5f5adbd5.dynamic.kabel-deutschland.de [95.90.219.213]) (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 2D9FD20834; Fri, 26 Oct 2018 17:25:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540574706; bh=NH/jFtg26Sqvz1Ye0YcXn8c+VYgyXxrNMpkdpPRD/tU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VubXXLQV6Qw/naseomYCeO/7QcR8M9aGkkvS1iJHHcichAURJEazVkL+HVydcsvKx ZNNR4XaypjvVLFJAurfv6qedrEDkOn1N8J8rNf5IR7FxombDOFjJU15NvV8SrBSoFT xpE+/0oa2prf+KZfD+1aQJ4JZ8m92X4PtawWUZ7M= Date: Fri, 26 Oct 2018 19:25:01 +0200 From: Jessica Yu To: Torsten Duwe Subject: [PATCH v2] arm64/module: use mod->klp_info section header information for livepatch modules Message-ID: <20181026172500.g65bl2p7cvey3qsx@linux-8ccs> References: <20181001140910.086E768BC7@newverein.lst.de> <20181001141652.5478C68BE1@newverein.lst.de> <20181023175553.gaobskk26koft6s2@linux-8ccs> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20181023175553.gaobskk26koft6s2@linux-8ccs> 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-20181026_102517_112076_D9CC572B X-CRM114-Status: GOOD ( 18.57 ) 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: Petr Mladek , 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, Miroslav Benes , 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 Acked-by: Will Deacon Acked-by: Ard Biesheuvel --- v2: - fix missing free_module_elf() in error path - move copy_module_elf() and module_finalize() out of post_relocation() to make error handling more clear - add braces to if-else block in arm64 module_frob_arch_sections() arch/arm64/include/asm/module.h | 1 + arch/arm64/kernel/module-plts.c | 17 ++++++++++++----- arch/arm64/kernel/module.c | 10 ++++++++++ kernel/module.c | 29 +++++++++++++++-------------- 4 files changed, 38 insertions(+), 19 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..851311ffd427 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -210,16 +210,23 @@ 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) && + } else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && !strcmp(secstrings + sechdrs[i].sh_name, - ".text.ftrace_trampoline")) + ".text.ftrace_trampoline")) { tramp = sechdrs + i; - else if (sechdrs[i].sh_type == SHT_SYMTAB) + } else if (sechdrs[i].sh_type == SHT_SYMTAB) { syms = (Elf64_Sym *)sechdrs[i].sh_addr; + } } if (!mod->arch.core.plt || !mod->arch.init.plt) { 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..611f4fe64370 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3365,7 +3365,7 @@ int __weak module_finalize(const Elf_Ehdr *hdr, return 0; } -static int post_relocation(struct module *mod, const struct load_info *info) +static void post_relocation(struct module *mod, const struct load_info *info) { /* Sort exception table now relocations are done. */ sort_extable(mod->extable, mod->extable + mod->num_exentries); @@ -3376,9 +3376,6 @@ static int post_relocation(struct module *mod, const struct load_info *info) /* Setup kallsyms-specific fields. */ add_kallsyms(mod, info); - - /* Arch-specific module finalizing. */ - return module_finalize(info->hdr, info->sechdrs, mod); } /* Is this module of this name done loading? No locks held. */ @@ -3726,9 +3723,18 @@ static int load_module(struct load_info *info, const char __user *uargs, if (err < 0) goto free_modinfo; - err = post_relocation(mod, info); + post_relocation(mod, info); + + if (is_livepatch_module(mod)) { + err = copy_module_elf(mod, info); + if (err < 0) + goto free_modinfo; + } + + /* Arch-specific module finalizing. */ + err = module_finalize(info->hdr, info->sechdrs, mod); if (err < 0) - goto free_modinfo; + goto free_module_elf; flush_module_icache(mod); @@ -3770,12 +3776,6 @@ 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 +3784,6 @@ 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); @@ -3809,6 +3807,9 @@ static int load_module(struct load_info *info, const char __user *uargs, kfree(mod->args); free_arch_cleanup: module_arch_cleanup(mod); + free_module_elf: + if (is_livepatch_module(mod)) + free_module_elf(mod); free_modinfo: free_modinfo(mod); free_unload: