From patchwork Sun Feb 12 23:31:40 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eddie Kovsky X-Patchwork-Id: 9568651 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id F2E4D60572 for ; Sun, 12 Feb 2017 23:32:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E7FC628066 for ; Sun, 12 Feb 2017 23:32:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DC87728112; Sun, 12 Feb 2017 23:32:30 +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=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 2380C28066 for ; Sun, 12 Feb 2017 23:32:29 +0000 (UTC) Received: (qmail 28405 invoked by uid 550); 12 Feb 2017 23:32:26 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 28258 invoked from network); 12 Feb 2017 23:32:25 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=edkovsky.org; s=mail; t=1486942334; bh=SckxKPth9bt9NHHDmYEsN3xnCrPQZamsn61AiZZ53qY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZaGszIYF2w5SKvNTMfQSi2yCEf9jx9VCNx1D/luzfNL4SCxTJF1dbfn706Hvx/KBX Uccq7DYbhjhEBFxgU7F/i+ZkQh4LSV2jm+v847Vvc+0fVy5gwO+Q8PayPcEPSIal8V iVc8kCOViVTudn1SYPPLqZuqkS7M5W5Ack9ZIgOw= From: Eddie Kovsky To: jeyu@redhat.com, rusty@rustcorp.com.au, keescook@chromium.org Cc: kernel-hardening@lists.openwall.com, Eddie Kovsky Date: Sun, 12 Feb 2017 16:31:40 -0700 Message-Id: <20170212233140.10606-3-ewk@edkovsky.org> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20170212233140.10606-1-ewk@edkovsky.org> References: <20170212233140.10606-1-ewk@edkovsky.org> X-Virus-Scanned: clamav-milter 0.99.2 at olympus X-Virus-Status: Clean Subject: [kernel-hardening] [RFC] [PATCH 2/2] extable: verify address is read-only X-Virus-Scanned: ClamAV using ClamSMTP Provide a mechanism to check if the address of a variable is const or ro_after_init. It mimics the existing functions that test if an address is inside the kernel's text section. Signed-off-by: Eddie Kovsky --- include/linux/kernel.h | 2 ++ kernel/extable.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) -- 2.11.1 diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 4c26dc3a8295..51beea39e6c4 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -444,6 +444,8 @@ extern int core_kernel_data(unsigned long addr); extern int __kernel_text_address(unsigned long addr); extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); +extern int core_kernel_ro_data(unsigned long addr); +extern int kernel_ro_address(unsigned long addr); unsigned long int_sqrt(unsigned long); diff --git a/kernel/extable.c b/kernel/extable.c index 6b0d09051efb..f5a29c4ae391 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -149,3 +149,34 @@ int func_ptr_is_kernel_text(void *ptr) return 1; return is_module_text_address(addr); } + +/** + * core_kernel_ro_data - Verify address points to read-only section + * @addr: address to test + * + */ +int core_kernel_ro_data(unsigned long addr) +{ + if (addr >= (unsigned long)__start_rodata && + addr < (unsigned long)__end_rodata) + return 1; + + if (addr >= (unsigned long)__start_data_ro_after_init && + addr < (unsigned long)__end_data_ro_after_init) + return 1; + + return 0; +} + +/* Verify that address is const or ro_after_init. */ +int kernel_ro_address(unsigned long addr) +{ + if (core_kernel_ro_data(addr)) + return 1; + if (is_module_ro_address(addr)) + return 1; + if (is_ftrace_trampoline(addr)) + return 1; + + return 0; +}