From patchwork Tue Oct 23 21:34:48 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Igor Stoppa X-Patchwork-Id: 10653711 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id BE8DB13A4 for ; Tue, 23 Oct 2018 21:36:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AA1022A3CD for ; Tue, 23 Oct 2018 21:36:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 999912A3D2; Tue, 23 Oct 2018 21:36:30 +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=-5.0 required=2.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FROM,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED 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 A37672A3CD for ; Tue, 23 Oct 2018 21:36:29 +0000 (UTC) Received: (qmail 13427 invoked by uid 550); 23 Oct 2018 21:36:11 -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 12241 invoked from network); 23 Oct 2018 21:36:10 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references:reply-to; bh=zu6YpzsO3OPxEg4tClPcjQ9+ceDNkNmVTbJmyduztxw=; b=IYU37E3Goc1gepM+z7hog9RH6DIyAowZ3kap0+WnwznOQYEPQmswmAxSGL4JWRQEyS CVrhUhp6EhYzB/yceyWg6J016IiEWahMGlmmJJMR8SB9NsCkUaysR15IMkJiU9XU5A4x MYbPNGz5r322XE/6vXeNUMLtZBrdp5hnW7p6Gu6ioi4MnKP5t0mRajj05ORcpQyv+vrY Z6ynoOqJzxtr0/3c7DGuoeWYCgLGwyy1UvRU4MZvg/8f07ITGGyeJcCceomGyRisd/Gm odqfJ5zXkKMEu4gInslFJueixysz3Std4Mztz2zYPYKLbOawgJ0QCO9GrluxawhCBR6S qfuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:reply-to; bh=zu6YpzsO3OPxEg4tClPcjQ9+ceDNkNmVTbJmyduztxw=; b=lPtlV8GADFY2EistCXuj7iJ0gf5c4ROWvY3K9k1uoHQYsNz3v7uBokv0I3PCdkaqpE acX1lQZnpmjYSrZctFuSGjhcos/eFGFcg2hypuOBinnsC1iSpZCRqZ8DhW9KNDHPBKWu kjeqf9OdTI5w3EHarE6JpppXdXGznF8lwFRoqe3KNvJ0RIf2IiO/p0TeoflHzaT+LVJk 7ONl/YrcNThJnmShTbZE5LHb3EyjXS4AHFJPEYbN0jBKSzsYxevcv/x1Ml9cCwPhhezq weV3KZrAuvB0XP05Z1B1Rvdp4C07GTu5qafq7eKjdzLYs4FG3mZznaM+zYwmqTkE1qvR dx7w== X-Gm-Message-State: ABuFfohuY69vZS5cI3UUfwQCkVDTo5M7/kLt9O3mBlo0lEg7E0Ic+Jyg pZe64lBxJZlSB3Lq/J06DpU= X-Google-Smtp-Source: ACcGV60Pq7KtfnwIP2lKFjHQF4lR+JAvWyiJuqcEsOhPvZE+obfCKGmgt17NFjnFkz3993bVkhoNew== X-Received: by 2002:a19:690d:: with SMTP id e13mr9045976lfc.84.1540330558395; Tue, 23 Oct 2018 14:35:58 -0700 (PDT) From: Igor Stoppa X-Google-Original-From: Igor Stoppa To: Mimi Zohar , Kees Cook , Matthew Wilcox , Dave Chinner , James Morris , Michal Hocko , kernel-hardening@lists.openwall.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org Cc: igor.stoppa@huawei.com, Dave Hansen , Jonathan Corbet , Laura Abbott , Arnd Bergmann , Thomas Gleixner , Kate Stewart , Greg Kroah-Hartman , Philippe Ombredanne , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 01/17] prmem: linker section for static write rare Date: Wed, 24 Oct 2018 00:34:48 +0300 Message-Id: <20181023213504.28905-2-igor.stoppa@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181023213504.28905-1-igor.stoppa@huawei.com> References: <20181023213504.28905-1-igor.stoppa@huawei.com> X-Virus-Scanned: ClamAV using ClamSMTP Introduce a section and a label for statically allocated write rare data. The label is named "__write_rare_after_init". As the name implies, after the init phase is completed, this section will be modifiable only by invoking write rare functions. NOTE: this needs rework, because the current write-rare mechanism works only on x86_64 and not arm64, due to arm64 mappings. Signed-off-by: Igor Stoppa CC: Arnd Bergmann CC: Thomas Gleixner CC: Kate Stewart CC: Greg Kroah-Hartman CC: Philippe Ombredanne CC: linux-arch@vger.kernel.org CC: linux-kernel@vger.kernel.org --- include/asm-generic/vmlinux.lds.h | 20 ++++++++++++++++++++ include/linux/cache.h | 17 +++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index d7701d466b60..fd40a15e3b24 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -300,6 +300,25 @@ . = __start_init_task + THREAD_SIZE; \ __end_init_task = .; +/* + * Allow architectures to handle wr_after_init data on their + * own by defining an empty WR_AFTER_INIT_DATA. + * However, it's important that pages containing WR_RARE data do not + * hold anything else, to avoid both accidentally unprotecting something + * that is supposed to stay read-only all the time and also to protect + * something else that is supposed to be writeable all the time. + */ +#ifndef WR_AFTER_INIT_DATA +#define WR_AFTER_INIT_DATA(align) \ + . = ALIGN(PAGE_SIZE); \ + __start_wr_after_init = .; \ + . = ALIGN(align); \ + *(.data..wr_after_init) \ + . = ALIGN(PAGE_SIZE); \ + __end_wr_after_init = .; \ + . = ALIGN(align); +#endif + /* * Allow architectures to handle ro_after_init data on their * own by defining an empty RO_AFTER_INIT_DATA. @@ -320,6 +339,7 @@ __start_rodata = .; \ *(.rodata) *(.rodata.*) \ RO_AFTER_INIT_DATA /* Read only after init */ \ + WR_AFTER_INIT_DATA(align) /* wr after init */ \ KEEP(*(__vermagic)) /* Kernel version magic */ \ . = ALIGN(8); \ __start___tracepoints_ptrs = .; \ diff --git a/include/linux/cache.h b/include/linux/cache.h index 750621e41d1c..9a7e7134b887 100644 --- a/include/linux/cache.h +++ b/include/linux/cache.h @@ -31,6 +31,23 @@ #define __ro_after_init __attribute__((__section__(".data..ro_after_init"))) #endif +/* + * __wr_after_init is used to mark objects that cannot be modified + * directly after init (i.e. after mark_rodata_ro() has been called). + * These objects become effectively read-only, from the perspective of + * performing a direct write, like a variable assignment. + * However, they can be altered through a dedicated function. + * It is intended for those objects which are occasionally modified after + * init, however they are modified so seldomly, that the extra cost from + * the indirect modification is either negligible or worth paying, for the + * sake of the protection gained. + */ +#ifndef __wr_after_init +#define __wr_after_init \ + __attribute__((__section__(".data..wr_after_init"))) +#endif + + #ifndef ____cacheline_aligned #define ____cacheline_aligned __attribute__((__aligned__(SMP_CACHE_BYTES))) #endif