From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751198AbdBRGH3 (ORCPT ); Sat, 18 Feb 2017 01:07:29 -0500 Received: from olympus.edkovsky.org ([72.14.187.238]:33462 "EHLO edkovsky.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750742AbdBRGH2 (ORCPT ); Sat, 18 Feb 2017 01:07:28 -0500 X-Greylist: delayed 483 seconds by postgrey-1.27 at vger.kernel.org; Sat, 18 Feb 2017 01:07:28 EST 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 Subject: [PATCH v2 2/3] extable: verify address is read-only 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> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(+) 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; +} -- 2.11.1