From patchwork Tue Apr 26 19:36:23 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Seth Forshee X-Patchwork-Id: 615132 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2001:1868:205::9]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3qvYLT4VkDz9t4h for ; Wed, 27 Apr 2016 05:38:57 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=canonical-com.20150623.gappssmtp.com header.i=@canonical-com.20150623.gappssmtp.com header.b=eDAQDD/i; dkim-atps=neutral Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1av8nt-0002ZX-8C; Tue, 26 Apr 2016 19:37:49 +0000 Received: from mail-ig0-x22a.google.com ([2607:f8b0:4001:c05::22a]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1av8nS-0001zH-2g for linux-mtd@lists.infradead.org; Tue, 26 Apr 2016 19:37:23 +0000 Received: by mail-ig0-x22a.google.com with SMTP id u10so52242286igr.1 for ; Tue, 26 Apr 2016 12:37:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=hfAVIOUNE/FEhSXuwJacQd4lvyAjACtDTcsa8KkVSEg=; b=eDAQDD/iKQ9QcBr4Ag4TeCvoZS8kiOxg7N++YYU9lH/X+8mDTZHdUVmwOse/RFNc1N FAHqy7c2JICV6lZ6LA2iqSAhr/1rk7I6ijKxvHJzVStbh432gpP+dP5HMCujGl3SWYSn nO+m0mBdIJcoizMwug+Y0CvU14zO2pLlCE7Wwnwe6TZlwkUDwaqlWwYZJVf2oQEfDfwT txsATnbDphmzQV7JWhCbDkkoryDVM7Nx3hmQ5jplHQGQYup9pQ5HPkgHZ1NoeSHAoBHo P3VaJ7I9fMOc6Cc6mQYSrqFU8uF84x9WpsbxZ+7fr6ZFbbkB/8cX4Lh1F7+d349y8Qhr Bwlw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=hfAVIOUNE/FEhSXuwJacQd4lvyAjACtDTcsa8KkVSEg=; b=aj61YiwY3cCri9eI0JuC4jTYQhvDwS+cBtoi98/f11GjR+iMnF1MOOrrdlGJCoA3Jq Qi6wOVdCAlUxGRvrkovmC9lbtRXOz9BPSK/hfpTqaVssc7viQzqxUhxmI54AHYj1UgLp XzyRYA1yQQvWBf/jUTGBH2lFQTd6zdTVACcLPdZWI5C/Ii0sdYCoNYJVuAmdHWwLKkDO 0FxZ65J5eu70VWvaSTTbC00BGPoWdKBhem2p/A2ut3LrWrkAvqtnhFHXB38B/Ioau9fH 2U+JgOZRCc6j8TySmW9WCUJuQKgp2RoYk3x76bX5IQo5GhXl/MiaqymjNTHP8C1gjG7N yURg== X-Gm-Message-State: AOPr4FXkfb0+pkRZvyqepIfOtCxwrcjw9RWuu1hGZU0prGw5BuCWgsRoY8ur24c58E5Jh0/6 X-Received: by 10.50.249.34 with SMTP id yr2mr21241027igc.28.1461699420969; Tue, 26 Apr 2016 12:37:00 -0700 (PDT) Received: from localhost ([2605:a601:aab:f920:39a1:5bcf:aa:5b00]) by smtp.gmail.com with ESMTPSA id i14sm2361090iod.34.2016.04.26.12.37.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 26 Apr 2016 12:37:00 -0700 (PDT) From: Seth Forshee To: "Eric W. Biederman" , Alexander Viro Subject: [PATCH v4 10/21] fs: Check for invalid i_uid in may_follow_link() Date: Tue, 26 Apr 2016 14:36:23 -0500 Message-Id: <1461699396-33000-11-git-send-email-seth.forshee@canonical.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> References: <1461699396-33000-1-git-send-email-seth.forshee@canonical.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160426_123722_252570_4D15D6B3 X-CRM114-Status: GOOD ( 11.50 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [2607:f8b0:4001:c05:0:0:0:22a listed in] [list.dnswl.org] -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-mtd@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-bcache@vger.kernel.org, Serge Hallyn , Seth Forshee , dm-devel@redhat.com, Miklos Szeredi , Richard Weinberger , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, fuse-devel@lists.sourceforge.net, Austin S Hemmelgarn , linux-mtd@lists.infradead.org, selinux@tycho.nsa.gov, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, Pavel Tikhomirov MIME-Version: 1.0 Sender: "linux-mtd" Errors-To: linux-mtd-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org Filesystem uids which don't map into a user namespace may result in inode->i_uid being INVALID_UID. A symlink and its parent could have different owners in the filesystem can both get mapped to INVALID_UID, which may result in following a symlink when this would not have otherwise been permitted when protected symlinks are enabled. Add a new helper function, uid_valid_eq(), and use this to validate that the ids in may_follow_link() are both equal and valid. Also add an equivalent helper for gids, which is currently unused. Signed-off-by: Seth Forshee Acked-by: Serge Hallyn Reviewed-by: Djalal Harouni --- fs/namei.c | 2 +- include/linux/uidgid.h | 10 ++++++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/fs/namei.c b/fs/namei.c index a29094c6f4a1..6fe8b0d8ca90 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -915,7 +915,7 @@ static inline int may_follow_link(struct nameidata *nd) return 0; /* Allowed if parent directory and link owner match. */ - if (uid_eq(parent->i_uid, inode->i_uid)) + if (uid_valid_eq(parent->i_uid, inode->i_uid)) return 0; if (nd->flags & LOOKUP_RCU) diff --git a/include/linux/uidgid.h b/include/linux/uidgid.h index 03835522dfcb..e09529fe2668 100644 --- a/include/linux/uidgid.h +++ b/include/linux/uidgid.h @@ -117,6 +117,16 @@ static inline bool gid_valid(kgid_t gid) return __kgid_val(gid) != (gid_t) -1; } +static inline bool uid_valid_eq(kuid_t left, kuid_t right) +{ + return uid_eq(left, right) && uid_valid(left); +} + +static inline bool gid_valid_eq(kgid_t left, kgid_t right) +{ + return gid_eq(left, right) && gid_valid(left); +} + #ifdef CONFIG_USER_NS extern kuid_t make_kuid(struct user_namespace *from, uid_t uid);