From patchwork Sat Feb 18 05:58:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eddie Kovsky X-Patchwork-Id: 9580997 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 F3B1E604A4 for ; Sat, 18 Feb 2017 05:59:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E47512878D for ; Sat, 18 Feb 2017 05:59:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D94AF28793; Sat, 18 Feb 2017 05:59:48 +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 EDF812878D for ; Sat, 18 Feb 2017 05:59:47 +0000 (UTC) Received: (qmail 7458 invoked by uid 550); 18 Feb 2017 05:59:46 -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 7413 invoked from network); 18 Feb 2017 05:59:45 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=edkovsky.org; s=mail; t=1487397574; bh=wepaF/E+VF6ydAy6VSOTzR5vW1sBP8caZyheF7/sjGw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eozEt1duTu3QGMgdyiZFsefjsYXPlJVlG7jXYwPLknMMmLvSt6F6QuDL1RfL8XtO5 W/I3+tKDMfGeYn+BNPDlZkZIOi2gAGrnClfNxtcQ6Aq26EUayLQCgxCAo01YbD2TG/ bINRytep4o9kDhLTUwcrL/wAGju1nhn3+C7Z5QbA= From: Eddie Kovsky To: jeyu@redhat.com, rusty@rustcorp.com.au, keescook@chromium.org, kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com Cc: linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Date: Fri, 17 Feb 2017 22:58:43 -0700 Message-Id: <20170218055844.1457-3-ewk@edkovsky.org> X-Mailer: git-send-email 2.11.1 In-Reply-To: <20170218055844.1457-1-ewk@edkovsky.org> References: <20170218055844.1457-1-ewk@edkovsky.org> X-Virus-Scanned: clamav-milter 0.99.2 at olympus X-Virus-Status: Clean Subject: [kernel-hardening] [PATCH v2 2/3] 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 | 29 +++++++++++++++++++++++++++++ 2 files changed, 31 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..e9608f129730 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -149,3 +149,32 @@ 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; + + return 0; +}