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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 5B17AC43331 for ; Fri, 3 Apr 2020 17:13:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D189A206F6 for ; Fri, 3 Apr 2020 17:13:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="BHzwZZov" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390939AbgDCRNI (ORCPT ); Fri, 3 Apr 2020 13:13:08 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49922 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726087AbgDCRNI (ORCPT ); Fri, 3 Apr 2020 13:13:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=Content-Type:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:In-Reply-To:References; bh=jv9Yf7cQCjMobtLa9/No1kE+P61DSmIa48Wq8z5iHcI=; b=BHzwZZovpp1Jkmqku0nupezxv5 IgyOcoOt6ZwXcDyaavQROpQU6N9/O/KIC91FiiaaKEAtkyQPzeWvh/+Va3qoUK8Tk6iK2DYiOSR2l QsCCEvPl11kbipf0xEqUmNCn24YAqgQiTinb3gkG3xnb0O0X4Qc3oeo1a7SyJhRy9up+2oavIeyBF tH9MQLug1ROCSisewPft92IoZj/Vp1sNPrrB3tvWvhOjxpmdCS5KHiK9m97aX1tkY3Nn63VOmkOrZ 8iyNHZ0s+ZNliRrey8DpfrAaLhZmFQvdZsRyEQl7KSrysGlPnpKXHpsxuhu0d+UUeaJaBoKr6oj55 otM7PcFA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jKPsO-0003oN-Ct; Fri, 03 Apr 2020 17:13:04 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 394F53060FD; Fri, 3 Apr 2020 19:13:03 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 250C12B125211; Fri, 3 Apr 2020 19:13:03 +0200 (CEST) Date: Fri, 3 Apr 2020 19:13:03 +0200 From: Peter Zijlstra To: jeyu@kernel.org Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , keescook@chromium.org, Josh Poimboeuf , Miroslav Benes Subject: [PATCH v2] module: Harden STRICT_MODULE_RWX Message-ID: <20200403171303.GK20760@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We're very close to enforcing W^X memory, refuse to load modules that violate this principle per construction. Signed-off-by: Peter Zijlstra (Intel) --- kernel/module.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) --- a/kernel/module.c +++ b/kernel/module.c @@ -2044,9 +2044,29 @@ static void module_enable_x(const struct frob_text(&mod->core_layout, set_memory_x); frob_text(&mod->init_layout, set_memory_x); } + +static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + const unsigned long shf_wx = SHF_WRITE|SHF_EXECINSTR; + int i; + + for (i = 0; i < hdr->e_shnum; i++) { + if ((sechdrs[i].sh_flags & shf_wx) == shf_wx) + return -ENOEXEC; + } + + return 0; +} + #else /* !CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ static void module_enable_nx(const struct module *mod) { } static void module_enable_x(const struct module *mod) { } +static int module_enforce_rwx_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs, + char *secstrings, struct module *mod) +{ + return 0; +} #endif /* CONFIG_ARCH_HAS_STRICT_MODULE_RWX */ @@ -3378,6 +3398,11 @@ static struct module *layout_and_allocat if (err < 0) return ERR_PTR(err); + err = module_enforce_rwx_sections(info->hdr, info->sechdrs, + info->secstrings, info->mod); + if (err < 0) + return ERR_PTR(err); + /* We will do a special allocation for per-cpu sections later. */ info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;