From patchwork Sun Jul 28 01:02:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aleksa Sarai X-Patchwork-Id: 11062779 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 EF6AB14E5 for ; Sun, 28 Jul 2019 01:04:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EC17C28905 for ; Sun, 28 Jul 2019 01:04:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DFF60289CD; Sun, 28 Jul 2019 01:04:55 +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=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 8544C28928 for ; Sun, 28 Jul 2019 01:04:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388281AbfG1BEv (ORCPT ); Sat, 27 Jul 2019 21:04:51 -0400 Received: from mx2.mailbox.org ([80.241.60.215]:49478 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726240AbfG1BEv (ORCPT ); Sat, 27 Jul 2019 21:04:51 -0400 Received: from smtp2.mailbox.org (smtp2.mailbox.org [IPv6:2001:67c:2050:105:465:1:2:0]) (using TLSv1.2 with cipher ECDHE-RSA-CHACHA20-POLY1305 (256/256 bits)) (No client certificate requested) by mx2.mailbox.org (Postfix) with ESMTPS id 6F4EBA10DC; Sun, 28 Jul 2019 03:04:46 +0200 (CEST) X-Virus-Scanned: amavisd-new at heinlein-support.de Received: from smtp2.mailbox.org ([80.241.60.241]) by spamfilter01.heinlein-hosting.de (spamfilter01.heinlein-hosting.de [80.241.56.115]) (amavisd-new, port 10030) with ESMTP id pibGlf-jZKFj; Sun, 28 Jul 2019 03:04:40 +0200 (CEST) From: Aleksa Sarai To: Al Viro , Jeff Layton , "J. Bruce Fields" , Arnd Bergmann , David Howells , Shuah Khan , Shuah Khan Cc: Aleksa Sarai , Eric Biederman , Andy Lutomirski , Andrew Morton , Alexei Starovoitov , Kees Cook , Jann Horn , Christian Brauner , Tycho Andersen , David Drysdale , Chanho Min , Oleg Nesterov , Aleksa Sarai , Linus Torvalds , containers@lists.linux-foundation.org, linux-alpha@vger.kernel.org, linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, sparclinux@vger.kernel.org Subject: [PATCH v11 2/8] procfs: switch magic-link modes to be more sane Date: Sun, 28 Jul 2019 11:02:01 +1000 Message-Id: <20190728010207.9781-3-cyphar@cyphar.com> In-Reply-To: <20190728010207.9781-1-cyphar@cyphar.com> References: <20190728010207.9781-1-cyphar@cyphar.com> MIME-Version: 1.0 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Now that magic-link modes are obeyed for file re-opening purposes, some of the pre-existing magic-link modes need to be adjusted to be more semantically correct. The most blatant example of this is /proc/self/exe, which had a mode of a+rwx even though tautologically the file could never be opened for writing (because it is the current->mm of a live process). With the new O_PATH restrictions, changing the default mode of these magic-links allows us to avoid delayed-access attacks such as we saw in CVE-2019-5736. Signed-off-by: Aleksa Sarai --- fs/proc/base.c | 20 ++++++++++---------- fs/proc/namespaces.c | 2 +- 2 files changed, 11 insertions(+), 11 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index ebea9501afb8..297242174402 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -133,9 +133,9 @@ struct pid_entry { #define DIR(NAME, MODE, iops, fops) \ NOD(NAME, (S_IFDIR|(MODE)), &iops, &fops, {} ) -#define LNK(NAME, get_link) \ - NOD(NAME, (S_IFLNK|S_IRWXUGO), \ - &proc_pid_link_inode_operations, NULL, \ +#define LNK(NAME, MODE, get_link) \ + NOD(NAME, (S_IFLNK|(MODE)), \ + &proc_pid_link_inode_operations, NULL, \ { .proc_get_link = get_link } ) #define REG(NAME, MODE, fops) \ NOD(NAME, (S_IFREG|(MODE)), NULL, &fops, {}) @@ -3028,9 +3028,9 @@ static const struct pid_entry tgid_base_stuff[] = { REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations), #endif REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations), - LNK("cwd", proc_cwd_link), - LNK("root", proc_root_link), - LNK("exe", proc_exe_link), + LNK("cwd", S_IRWXUGO, proc_cwd_link), + LNK("root", S_IRWXUGO, proc_root_link), + LNK("exe", S_IRUGO|S_IXUGO, proc_exe_link), REG("mounts", S_IRUGO, proc_mounts_operations), REG("mountinfo", S_IRUGO, proc_mountinfo_operations), REG("mountstats", S_IRUSR, proc_mountstats_operations), @@ -3429,11 +3429,11 @@ static const struct pid_entry tid_base_stuff[] = { REG("numa_maps", S_IRUGO, proc_pid_numa_maps_operations), #endif REG("mem", S_IRUSR|S_IWUSR, proc_mem_operations), - LNK("cwd", proc_cwd_link), - LNK("root", proc_root_link), - LNK("exe", proc_exe_link), + LNK("cwd", S_IRWXUGO, proc_cwd_link), + LNK("root", S_IRWXUGO, proc_root_link), + LNK("exe", S_IRUGO|S_IXUGO, proc_exe_link), REG("mounts", S_IRUGO, proc_mounts_operations), - REG("mountinfo", S_IRUGO, proc_mountinfo_operations), + REG("mountinfo", S_IRUGO, proc_mountinfo_operations), #ifdef CONFIG_PROC_PAGE_MONITOR REG("clear_refs", S_IWUSR, proc_clear_refs_operations), REG("smaps", S_IRUGO, proc_pid_smaps_operations), diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index dd2b35f78b09..cd1e130913f7 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -94,7 +94,7 @@ static struct dentry *proc_ns_instantiate(struct dentry *dentry, struct inode *inode; struct proc_inode *ei; - inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRWXUGO); + inode = proc_pid_make_inode(dentry->d_sb, task, S_IFLNK | S_IRUGO); if (!inode) return ERR_PTR(-ENOENT);