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d="scan'208";a="15642555" Received: from mail-ig0-f175.google.com ([209.85.213.175]) by emsm-gh1-uea11.nsa.gov with ESMTP/TLS/AES128-GCM-SHA256; 26 Apr 2016 19:37:01 +0000 Received: by mail-ig0-f175.google.com with SMTP id u10so52242295igr.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=HKG3sPaQr4Cng48jxOGOvC6gz+xR57sR2cMTwKJI3wjbEapfxgJyiyp0mUL8JIvqF6 AlivzUH8FeeG8cb/Xixj5CfA0OB+XcEAy3zgW8lwKy5zzp7GpdxJmrQ1JU/emy0lYlVC H+yOZza27BFHD4ajSSVpEY5oUXUOiRAy6c6SE6kDPuXQNCLCH6gYysH08YNR+ZzA/l6Y N6lA8FGzFn4YVc9ebQaiSBV4rdBYPYb+zyxjl48g7PehlkFX2J+VYyQYeq9vkcF1tmhU b8BWXh+UWU/WbvCqlzULzErCArAE9DxeAgmHB/CRXOhkZh5XYgy4rkl9fuSnR9rDS31m VybQ== X-Gm-Message-State: AOPr4FWXmkhluJippbwetzyvskUCAy2ms3/gGcl4FG9ruB64Wf0nvB1AehT8Ca27q752fiDX 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-Mailman-Approved-At: Tue, 26 Apr 2016 16:11:01 -0400 X-BeenThere: selinux@tycho.nsa.gov X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Security-Enhanced Linux \(SELinux\) mailing list" List-Post: List-Help: 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 Errors-To: selinux-bounces@tycho.nsa.gov Sender: "Selinux" X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RP_MATCHES_RCVD, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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);