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=-6.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,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 79750ECDE46 for ; Thu, 25 Oct 2018 11:42:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A4172083E for ; Thu, 25 Oct 2018 11:42:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="iQNUfavf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3A4172083E 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 S1727386AbeJYUO7 (ORCPT ); Thu, 25 Oct 2018 16:14:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:32988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727206AbeJYUO7 (ORCPT ); Thu, 25 Oct 2018 16:14:59 -0400 Received: from linux-8ccs (ip5f5adbf1.dynamic.kabel-deutschland.de [95.90.219.241]) (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 CDDC620831; Thu, 25 Oct 2018 11:42:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1540467753; bh=/lDqC7tsHJhi2MFD4gFFiKAERUxCmSaUl7jEVgZA7nA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=iQNUfavfR6WeKhWeIV/ejJRS5C70LCFCDm/inOk9a6oeMQ+2TfKVFoWQq5Bu1lw8d gEwqaFa4oAwlKYCniWuFjePxq4Ukn3NdSOdHT2vakv+mPQKI/lJ02pzvnpnurGdk9P EkIp17krxKtNPn5TNMb8tO05TnB0cOTRlPZ/GeKo= Date: Thu, 25 Oct 2018 13:42:28 +0200 From: Jessica Yu To: Miroslav Benes Cc: Petr Mladek , Torsten Duwe , 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: Re: [PATCH] arm64/module: use mod->klp_info section header information Message-ID: <20181025114228.4zkwvdfwrwhngwod@linux-8ccs> References: <20181001140910.086E768BC7@newverein.lst.de> <20181001141652.5478C68BE1@newverein.lst.de> <20181023175553.gaobskk26koft6s2@linux-8ccs> <20181025080816.525dppcfrrevf6jc@pathway.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: 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 +++ Miroslav Benes [25/10/18 11:00 +0200]: >On Thu, 25 Oct 2018, Petr Mladek wrote: > >> On Tue 2018-10-23 19:55:54, Jessica Yu wrote: >> > 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. >> > >> > 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) >> >> if (err < 0 && is_livepatch_module(mod)) > >Ah, right. > >> > + free_module_elf(mod); >> > + >> > + return err; >> > } >> >> Also we need to free the copied stuff in load_module() when >> anything called after post_relocation() fails. I think >> that the following would work: >> >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -3823,6 +3823,8 @@ static int load_module(struct load_info *info, const char __user *uargs, >> kfree(mod->args); >> free_arch_cleanup: >> module_arch_cleanup(mod); >> + if (is_livepatch_module(mod)) >> + free_module_elf(mod); >> free_modinfo: >> free_modinfo(mod); >> free_unload: > >Yes, we need to free it somewhere and I missed it. free_arch_cleanup seems >to be the correct place. Good catches, thank you both! >> But I suggest to just move copy_module_elf() up and keep >> calling it from load_module() directly. It would make >> the error handling more clear. > >Unfortunately it is not that simple. arm64's module_finalize() uses >mod->klp_info with the patch, so copy_module_elf() must be called before. >We could move module_finalize() from post_relocation() to load_module() >and place copy_module_elf() between those two, but I don't know. That's up >to Jessica. Yeah, it's a stylistic preference - will shuffle those calls around and see what looks best. v2 to come shortly. Thanks! Jessica From mboxrd@z Thu Jan 1 00:00:00 1970 From: jeyu@kernel.org (Jessica Yu) Date: Thu, 25 Oct 2018 13:42:28 +0200 Subject: [PATCH] arm64/module: use mod->klp_info section header information In-Reply-To: References: <20181001140910.086E768BC7@newverein.lst.de> <20181001141652.5478C68BE1@newverein.lst.de> <20181023175553.gaobskk26koft6s2@linux-8ccs> <20181025080816.525dppcfrrevf6jc@pathway.suse.cz> Message-ID: <20181025114228.4zkwvdfwrwhngwod@linux-8ccs> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org +++ Miroslav Benes [25/10/18 11:00 +0200]: >On Thu, 25 Oct 2018, Petr Mladek wrote: > >> On Tue 2018-10-23 19:55:54, Jessica Yu wrote: >> > 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. >> > >> > 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) >> >> if (err < 0 && is_livepatch_module(mod)) > >Ah, right. > >> > + free_module_elf(mod); >> > + >> > + return err; >> > } >> >> Also we need to free the copied stuff in load_module() when >> anything called after post_relocation() fails. I think >> that the following would work: >> >> --- a/kernel/module.c >> +++ b/kernel/module.c >> @@ -3823,6 +3823,8 @@ static int load_module(struct load_info *info, const char __user *uargs, >> kfree(mod->args); >> free_arch_cleanup: >> module_arch_cleanup(mod); >> + if (is_livepatch_module(mod)) >> + free_module_elf(mod); >> free_modinfo: >> free_modinfo(mod); >> free_unload: > >Yes, we need to free it somewhere and I missed it. free_arch_cleanup seems >to be the correct place. Good catches, thank you both! >> But I suggest to just move copy_module_elf() up and keep >> calling it from load_module() directly. It would make >> the error handling more clear. > >Unfortunately it is not that simple. arm64's module_finalize() uses >mod->klp_info with the patch, so copy_module_elf() must be called before. >We could move module_finalize() from post_relocation() to load_module() >and place copy_module_elf() between those two, but I don't know. That's up >to Jessica. Yeah, it's a stylistic preference - will shuffle those calls around and see what looks best. v2 to come shortly. Thanks! Jessica