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[23.128.96.18]) by mx.google.com with ESMTP id s18si3489098edx.6.2020.07.30.09.32.34; Thu, 30 Jul 2020 09:32:56 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729965AbgG3QaA (ORCPT + 99 others); Thu, 30 Jul 2020 12:30:00 -0400 Received: from verein.lst.de ([213.95.11.211]:56532 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726353AbgG3QaA (ORCPT ); Thu, 30 Jul 2020 12:30:00 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 70B0468BEB; Thu, 30 Jul 2020 18:29:57 +0200 (CEST) Date: Thu, 30 Jul 2020 18:29:57 +0200 From: Christoph Hellwig To: Jessica Yu Cc: Christoph Hellwig , Greg Kroah-Hartman , open list Subject: Re: [PATCH 8/8] modules: inherit TAINT_PROPRIETARY_MODULE Message-ID: <20200730162957.GA22469@lst.de> References: <20200730061027.29472-1-hch@lst.de> <20200730061027.29472-9-hch@lst.de> <20200730141232.GA31539@linux-8ccs> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200730141232.GA31539@linux-8ccs> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 30, 2020 at 04:12:32PM +0200, Jessica Yu wrote: >> + if (owner && test_bit(TAINT_PROPRIETARY_MODULE, &owner->taints)) { >> + if (mod->using_gplonly_symbols) { >> + sym = NULL; >> + goto getname; >> + } >> + add_taint_module(mod, TAINT_PROPRIETARY_MODULE, >> + LOCKDEP_NOW_UNRELIABLE); >> + } > > Sorry that I didn't think of this yesterday, but I'm wondering if we > should print a warning before add_taint_module(). Maybe something > along the lines of, "%s: module uses symbols from proprietary module > %s, inheriting taint.", with %s being mod->name, owner->name. We can > check mod->taints for TAINT_PROPRIETARY_MODULE and print the warning once. > > Additionally, maybe it's a good idea to print an error before goto > getname (e.g., "%s: module using GPL-only symbols uses symbols from > proprietary module %s."), so one would know why the module load > failed, right now this manifests itself as an unknown symbol error. > > Otherwise, this patchset looks good to me and I agree with it in > principle. Thanks Christoph! What about this version? It also factors the code out into a new helper, and replaces the add_taint_module with a simple set_bit, as the system-wide tain must have been set before by definition: --- From 25e928b6b691911717d30b3449e56fca3e13dba9 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Tue, 28 Jul 2020 23:33:33 +0200 Subject: modules: inherit TAINT_PROPRIETARY_MODULE If a TAINT_PROPRIETARY_MODULE exports symbol, inherit the taint flag for all modules importing these symbols, and don't allow loading symbols from TAINT_PROPRIETARY_MODULE modules if the module previously imported gplonly symbols. Add a anti-circumvention devices so people don't accidentally get themselves into trouble this way. Comment from Greg: "Ah, the proven-to-be-illegal "GPL Condom" defense :)" Signed-off-by: Christoph Hellwig Reviewed-by: Greg Kroah-Hartman --- include/linux/module.h | 1 + kernel/module.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) diff --git a/include/linux/module.h b/include/linux/module.h index 30b0f5fcdb3c37..e30ed5fa33a738 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -389,6 +389,7 @@ struct module { unsigned int num_gpl_syms; const struct kernel_symbol *gpl_syms; const s32 *gpl_crcs; + bool using_gplonly_symbols; #ifdef CONFIG_UNUSED_SYMBOLS /* unused exported symbols. */ diff --git a/kernel/module.c b/kernel/module.c index afb2bfdd5134b3..81d5facce28c14 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1431,6 +1431,24 @@ static int verify_namespace_is_imported(const struct load_info *info, return 0; } +static bool inherit_taint(struct module *mod, struct module *owner) +{ + if (!owner || !test_bit(TAINT_PROPRIETARY_MODULE, &owner->taints)) + return true; + + if (mod->using_gplonly_symbols) { + pr_info("%s: module using GPL-only symbols uses symbols from proprietary module %s.\n", + mod->name, owner->name); + return false; + } + + if (!test_bit(TAINT_PROPRIETARY_MODULE, &mod->taints)) { + pr_info("%s: module uses symbols from proprietary module %s, inheriting taint.\n", + mod->name, owner->name); + set_bit(TAINT_PROPRIETARY_MODULE, &mod->taints); + } + return true; +} /* Resolve a symbol for this module. I.e. if we find one, record usage. */ static const struct kernel_symbol *resolve_symbol(struct module *mod, @@ -1456,6 +1474,14 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod, if (!sym) goto unlock; + if (license == GPL_ONLY) + mod->using_gplonly_symbols = true; + + if (!inherit_taint(mod, owner)) { + sym = NULL; + goto getname; + } + if (!check_version(info, name, mod, crc)) { sym = ERR_PTR(-EINVAL); goto getname; -- 2.27.0