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[209.85.220.65]) by mx.google.com with SMTPS id ca12sor2885175pjb.6.2019.07.31.09.58.11 for (Google Transport Security); Wed, 31 Jul 2019 09:58:11 -0700 (PDT) Received-SPF: pass (google.com: domain of salyzyn@android.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@android.com header.s=20161025 header.b=cfX4VNn7; spf=pass (google.com: domain of salyzyn@android.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=salyzyn@android.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=android.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=YkWr+p+vKLuVNlEdLhOL/tn/V0J5xAeOTfzwbmW2id8=; b=cfX4VNn7i5fVUAJEVA4MBhomWV9u/SiICGvW/8hoXIHAFSEgly0mFbnQ+ACtuwiC3g IpRmu1ckKjW2mFtirOT4pZeZvT2dDPhZMzF32ZvoQFr92hPVsLC2dNO3QsACLmwar0UV QGuSfotvuKuTlqK5sSL0gn6Mhis1cY41gMWMYYlYUWkSVqwTLLDgqF7CYEi0YCD1g00b 7XO/I47/oxluNGrRhfkGi6MsDix8d8wmsmYqbtCrJdMXSv2+AjyqFMUYQjA2L9of7CoM 8oMQRrlSd8a/C7QbtWiQIXkLjDxq+jhIt0VkS66EI4A6SO7z2CwCPG6R7kaiAWc0Io97 PoBw== X-Google-Smtp-Source: APXvYqy8vRIpYoYhq+l1XHKOf/Pp65RQkYrvXTYdFcAiznSLIUoJDMNElyzOyLh9v1G4MbxuSIIkEQ== X-Received: by 2002:a17:90a:2041:: with SMTP id n59mr3794829pjc.6.1564592291310; Wed, 31 Jul 2019 09:58:11 -0700 (PDT) Received: from nebulus.mtv.corp.google.com ([2620:15c:211:200:5404:91ba:59dc:9400]) by smtp.gmail.com with ESMTPSA id f72sm2245954pjg.10.2019.07.31.09.58.09 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 31 Jul 2019 09:58:10 -0700 (PDT) From: Mark Salyzyn To: linux-kernel@vger.kernel.org Cc: kernel-team@android.com, Mark Salyzyn , Miklos Szeredi , Jonathan Corbet , Vivek Goyal , "Eric W . Biederman" , Amir Goldstein , Randy Dunlap , Stephen Smalley , linux-unionfs@vger.kernel.org, linux-doc@vger.kernel.org, Eric Van Hensbergen , Latchesar Ionkov , Dominique Martinet , David Howells , Chris Mason , Josef Bacik , David Sterba , Jeff Layton , Sage Weil , Ilya Dryomov , Steve French , Tyler Hicks , Jan Kara , Theodore Ts'o , Andreas Dilger , Jaegeuk Kim , Chao Yu , Bob Peterson , Andreas Gruenbacher , David Woodhouse , Richard Weinberger , Dave Kleikamp , Greg Kroah-Hartman , Tejun Heo , Trond Myklebust , Anna Schumaker , Mark Fasheh , Joel Becker , Joseph Qi , Mike Marshall , Martin Brandenburg , Alexander Viro , Phillip Lougher , "Darrick J . Wong" , linux-xfs@vger.kernel.org, Hugh Dickins , "David S . Miller" , Andrew Morton , Mathieu Malaterre , =?utf-8?q?Ernesto_A_=2E_Fern=C3=A1nde?= =?utf-8?q?z?= , Vyacheslav Dubeyko , v9fs-developer@lists.sourceforge.net, linux-afs@lists.infradead.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, ecryptfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, cluster-devel@redhat.com, linux-mtd@lists.infradead.org, jfs-discussion@lists.sourceforge.net, linux-nfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, devel@lists.orangefs.org, reiserfs-devel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linux-security-module@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v13 0/5] overlayfs override_creds=off Date: Wed, 31 Jul 2019 09:57:55 -0700 Message-Id: <20190731165803.4755-1-salyzyn@android.com> X-Mailer: git-send-email 2.22.0.770.g0f2c4a37fd-goog MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP Patch series: overlayfs: check CAP_DAC_READ_SEARCH before issuing exportfs_decode_fh Add flags option to get xattr method paired to __vfs_getxattr overlayfs: handle XATTR_NOSECURITY flag for get xattr method overlayfs: internal getxattr operations without sepolicy checking overlayfs: override_creds=off option bypass creator_cred The first four patches address fundamental security issues that should be solved regardless of the override_creds=off feature. on them). The fifth adds the feature depends on these other fixes. By default, all access to the upper, lower and work directories is the recorded mounter's MAC and DAC credentials. The incoming accesses are checked against the caller's credentials. If the principles of least privilege are applied for sepolicy, the mounter's credentials might not overlap the credentials of the caller's when accessing the overlayfs filesystem. For example, a file that a lower DAC privileged caller can execute, is MAC denied to the generally higher DAC privileged mounter, to prevent an attack vector. We add the option to turn off override_creds in the mount options; all subsequent operations after mount on the filesystem will be only the caller's credentials. The module boolean parameter and mount option override_creds is also added as a presence check for this "feature", existence of /sys/module/overlay/parameters/overlay_creds Signed-off-by: Mark Salyzyn Cc: Miklos Szeredi Cc: Jonathan Corbet Cc: Vivek Goyal Cc: Eric W. Biederman Cc: Amir Goldstein Cc: Randy Dunlap Cc: Stephen Smalley Cc: linux-unionfs@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Eric Van Hensbergen Cc: Latchesar Ionkov Cc: Dominique Martinet Cc: David Howells Cc: Chris Mason Cc: Josef Bacik Cc: David Sterba Cc: Jeff Layton Cc: Sage Weil Cc: Ilya Dryomov Cc: Steve French Cc: Tyler Hicks Cc: Jan Kara Cc: Theodore Ts'o Cc: Andreas Dilger Cc: Jaegeuk Kim Cc: Chao Yu Cc: Bob Peterson Cc: Andreas Gruenbacher Cc: David Woodhouse Cc: Richard Weinberger Cc: Dave Kleikamp Cc: Greg Kroah-Hartman Cc: Tejun Heo Cc: Trond Myklebust Cc: Anna Schumaker Cc: Mark Fasheh Cc: Joel Becker Cc: Joseph Qi Cc: Mike Marshall Cc: Martin Brandenburg Cc: Alexander Viro Cc: Phillip Lougher Cc: Darrick J. Wong Cc: linux-xfs@vger.kernel.org Cc: Hugh Dickins Cc: David S. Miller Cc: Andrew Morton Cc: Mathieu Malaterre Cc: Ernesto A. Fernández Cc: Vyacheslav Dubeyko Cc: v9fs-developer@lists.sourceforge.net Cc: linux-afs@lists.infradead.org Cc: linux-btrfs@vger.kernel.org Cc: ceph-devel@vger.kernel.org Cc: linux-cifs@vger.kernel.org Cc: samba-technical@lists.samba.org Cc: ecryptfs@vger.kernel.org Cc: linux-ext4@vger.kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net Cc: linux-fsdevel@vger.kernel.org Cc: cluster-devel@redhat.com Cc: linux-mtd@lists.infradead.org Cc: jfs-discussion@lists.sourceforge.net Cc: linux-nfs@vger.kernel.org Cc: ocfs2-devel@oss.oracle.com Cc: devel@lists.orangefs.org Cc: reiserfs-devel@vger.kernel.org Cc: linux-mm@kvack.org Cc: netdev@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: stable@vger.kernel.org # 4.4, 4.9, 4.14 & 4.19 Signed-off-by: Mark Salyzyn --- v13: - add flags argument to __vfs_getxattr - drop GFP_NOFS side-effect v12: - Restore squished out patch 2 and 3 in the series, then change algorithm to add flags argument. Per-thread flag is a large security surface. v11: - Squish out v10 introduced patch 2 and 3 in the series, then and use per-thread flag instead for nesting. - Switch name to ovl_do_vds_getxattr for __vds_getxattr wrapper. - Add sb argument to ovl_revert_creds to match future work. v10: - Return NULL on CAP_DAC_READ_SEARCH - Add __get xattr method to solve sepolicy logging issue - Drop unnecessary sys_admin sepolicy checking for administrative driver internal xattr functions. v6: - Drop CONFIG_OVERLAY_FS_OVERRIDE_CREDS. - Do better with the documentation, drop rationalizations. - pr_warn message adjusted to report consequences. v5: - beefed up the caveats in the Documentation - Is dependent on "overlayfs: check CAP_DAC_READ_SEARCH before issuing exportfs_decode_fh" "overlayfs: check CAP_MKNOD before issuing vfs_whiteout" - Added prwarn when override_creds=off v4: - spelling and grammar errors in text v3: - Change name from caller_credentials / creator_credentials to the boolean override_creds. - Changed from creator to mounter credentials. - Updated and fortified the documentation. - Added CONFIG_OVERLAY_FS_OVERRIDE_CREDS v2: - Forward port changed attr to stat, resulting in a build error. - altered commit message.