From patchwork Fri Apr 26 23:22:50 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nadav Amit X-Patchwork-Id: 10920045 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 4406614DB for ; Sat, 27 Apr 2019 06:44:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 353C128E6B for ; Sat, 27 Apr 2019 06:44:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 28F2528E7B; Sat, 27 Apr 2019 06:44:50 +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=-5.5 required=2.0 tests=BAYES_00,DATE_IN_PAST_06_12, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CD5A828E6B for ; Sat, 27 Apr 2019 06:44:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726048AbfD0Goi (ORCPT ); Sat, 27 Apr 2019 02:44:38 -0400 Received: from mail-pf1-f196.google.com ([209.85.210.196]:42640 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726509AbfD0GnV (ORCPT ); Sat, 27 Apr 2019 02:43:21 -0400 Received: by mail-pf1-f196.google.com with SMTP id w25so2743878pfi.9; Fri, 26 Apr 2019 23:43:21 -0700 (PDT) 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; bh=yNv4uuWY37+QDIo+8eJ5Cs1RQKFygWuhu/mUpTFc+50=; b=qfcv0jVylRwgUSdFp0yVo6y3SoCAOjol9XbR7W5+lwraaEg2QoXyt+VrAjGp9wzdAn BOm9G9cC4mrsWbrKkWfeWua0CLcUhNFX2UYmr160CAGJNRPhpKunjycWCJnpjaUptQXK FymoezD52jYoCa9vw1d8DrTtNcDpUD3gesH2ZoYEwsgq0bZE6tTukM9zPOscjJPRRiHd 0d0EQKT1ASnMLtYxkgiq4MVCWAUZf/kjKC/u6ibFbPlbEhDhs/jBfSTvPAadE2T4MBPs yoHMRLVUDfJJ0O31Q2uS3OPiszz2lAVHUHfzcDpTk8KxpsBn4aqr0vTCALbdk7a/EPYd 2uWQ== 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; bh=yNv4uuWY37+QDIo+8eJ5Cs1RQKFygWuhu/mUpTFc+50=; b=e36XDmzl6UQXWwFVnf1Aho7OYa6xYxx/ohzJMVW9lHybNH2PZQdH8bKlDrUn2puVx/ HrODl7AvP0qb/38oQYRDHwjENuuFmbysNLhayn7KAjkWNwmzWxpb2p9wZZ80Kko0zlOh m33D5qlUf4EpEoI6Yo/raL9lm9KANbzYTczEf8jqvJCW+uQV8cj1zbkIOY30ayPWO6t7 KMTkHoRxr5yKENMHV86B6bkDzj3rbmHTunDaJ+nLe5iwQLo8qNxwxouY/901FCPIJnuE bdsvfOwbpKfu85tnX6J13UwqPSchNti/M6I4yUwYo9OUmbOun9hVf8MKHSlrGLRSum/Y xuWQ== X-Gm-Message-State: APjAAAVic7Kmx599MCiIJZgM1lzjuP0Vyvi5p/aQtl7ZrzCe/B2QJNIR z05MD8SrRAYoLHRVtfO0bxk= X-Google-Smtp-Source: APXvYqxCgMCnuubydaHXfJIDthz2u46RkKoNrhpM9xg9spe5Zm1Eq7YBRg8tloTlDMLwvkBDrQMPvQ== X-Received: by 2002:a63:7f0b:: with SMTP id a11mr44847434pgd.234.1556347400564; Fri, 26 Apr 2019 23:43:20 -0700 (PDT) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id j22sm36460145pfn.129.2019.04.26.23.43.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Apr 2019 23:43:20 -0700 (PDT) From: nadav.amit@gmail.com To: Peter Zijlstra , Borislav Petkov , Andy Lutomirski , Ingo Molnar Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, Thomas Gleixner , Nadav Amit , Dave Hansen , linux_dti@icloud.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, akpm@linux-foundation.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, will.deacon@arm.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, deneen.t.dock@intel.com, Rick Edgecombe , Nadav Amit Subject: [PATCH v6 11/24] x86/kprobes: Set instruction page as executable Date: Fri, 26 Apr 2019 16:22:50 -0700 Message-Id: <20190426232303.28381-12-nadav.amit@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190426232303.28381-1-nadav.amit@gmail.com> References: <20190426232303.28381-1-nadav.amit@gmail.com> Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: Nadav Amit Set the page as executable after allocation. This patch is a preparatory patch for a following patch that makes module allocated pages non-executable. While at it, do some small cleanup of what appears to be unnecessary masking. Acked-by: Masami Hiramatsu Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe --- arch/x86/kernel/kprobes/core.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index a034cb808e7e..1591852d3ac4 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -431,8 +431,20 @@ void *alloc_insn_page(void) void *page; page = module_alloc(PAGE_SIZE); - if (page) - set_memory_ro((unsigned long)page & PAGE_MASK, 1); + if (!page) + return NULL; + + /* + * First make the page read-only, and only then make it executable to + * prevent it from being W+X in between. + */ + set_memory_ro((unsigned long)page, 1); + + /* + * TODO: Once additional kernel code protection mechanisms are set, ensure + * that the page was not maliciously altered and it is still zeroed. + */ + set_memory_x((unsigned long)page, 1); return page; } @@ -440,8 +452,12 @@ void *alloc_insn_page(void) /* Recover page to RW mode before releasing it */ void free_insn_page(void *page) { - set_memory_nx((unsigned long)page & PAGE_MASK, 1); - set_memory_rw((unsigned long)page & PAGE_MASK, 1); + /* + * First make the page non-executable, and only then make it writable to + * prevent it from being W+X in between. + */ + set_memory_nx((unsigned long)page, 1); + set_memory_rw((unsigned long)page, 1); module_memfree(page); }