From patchwork Mon Oct 19 11:52:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Salyzyn X-Patchwork-Id: 11844209 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5B63814B4 for ; Mon, 19 Oct 2020 11:53:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27833222B8 for ; Mon, 19 Oct 2020 11:53:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="k5COJ/7G" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727163AbgJSLxK (ORCPT ); Mon, 19 Oct 2020 07:53:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726588AbgJSLxJ (ORCPT ); Mon, 19 Oct 2020 07:53:09 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01D4BC0613D0 for ; Mon, 19 Oct 2020 04:53:08 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id w11so4851854pll.8 for ; Mon, 19 Oct 2020 04:53:08 -0700 (PDT) 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=cd0IbTkhiLHMnOo5qjbBSQNOqKZEtNi0Z2jN3s0JZ68=; b=k5COJ/7GIPiX2Bm3xsv3BHBknU06Ek53XKH5bqWcovWXBagETrw+FGun9O5l8KxyF3 p/+N9AUAxZ5Nx3ng6GbEqs/gr7QqAi2ONjeBRAyLuUzttkbibtSQStSd1LwlPsJBw9cW nYcZQ0ll36s80jmryDMxWBWWpdMoLbKRUQunB39/McmKqdhJY8Y1gS9H4sPik6nPW4Pt v8a1GyteLqq7KN1vY8CRvSpm/f2MM4X6AkyWcZm1siLipxzhkInr2VmwIwy9H5gND44K 0TDn77i6LZVIpIeowPqsAlp6tC7gf45m3/7Vq3qSASM2YwasvNYNC8yZ+a67wMwKNPu0 ls/Q== 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:mime-version :content-transfer-encoding; bh=cd0IbTkhiLHMnOo5qjbBSQNOqKZEtNi0Z2jN3s0JZ68=; b=MEA4DInE3lFGYYv5fZrdA6Um3DvNeQxR99gARGgXZ3tjO9eNBdpvdCDI1HAlAwnDAa 1jFZ3+Jk2dGnqWIrA29okD24/uEwl59ioPJk7PzKPGMvShwhA5KyYqOmKmpCJoCDegi6 YI55+vkExeWT0kTXinXrXx9mUXnLTm82GZIFjj1A6mG22EZMQU6gfz400w/jFB1MklA6 EqOpq7xAfZDdxX4rMgmuJwCZxbXKThU7AWgfHfCJdZL5uUaBrT3xoTA1uo0sqPDIAvA1 PjKSOIZc3vUfhY+Bd+C5p0Hbq8j+hsx44MaAwC4FU0c3iFaGBHi1jlLmv+jJPp7reEeG ViOw== X-Gm-Message-State: AOAM533QvbqE9WG4xJhpXV9BOtkfMWJpkyRGU3X5Hf7jP/xcLwxOLUfn TM2MXKRFCOHxZA8ujcnDdwzifg== X-Google-Smtp-Source: ABdhPJwVTBnbUb5J6jLEfI/u7ZOZbeWRazgv5iGiVryaPhmMtZ2Hn3uWu6mNLAKjpLwG8Cc//WRVgg== X-Received: by 2002:a17:90b:4910:: with SMTP id kr16mr13164681pjb.227.1603108388434; Mon, 19 Oct 2020 04:53:08 -0700 (PDT) Received: from nebulus.mtv.corp.google.com ([2620:15c:211:200:4a0f:cfff:fe35:d61b]) by smtp.gmail.com with ESMTPSA id w68sm12128099pfb.108.2020.10.19.04.53.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2020 04:53:07 -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 , John Stultz , linux-doc@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v15 0/4] overlayfs override_creds=off & nested get xattr fix Date: Mon, 19 Oct 2020 04:52:35 -0700 Message-Id: <20201019115239.2732422-1-salyzyn@android.com> X-Mailer: git-send-email 2.29.0.rc1.297.gfa9743e501-goog MIME-Version: 1.0 Precedence: bulk List-ID: Mark Salyzyn (3): Add flags option to get xattr method paired to __vfs_getxattr overlayfs: handle XATTR_NOSECURITY flag for get xattr method overlayfs: override_creds=off option bypass creator_cred Mark Salyzyn + John Stultz (1): overlayfs: inode_owner_or_capable called during execv The first three patches address fundamental security issues that should be solved regardless of the override_creds=off feature. The fourth 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: John Stultz Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org To: linux-fsdevel@vger.kernel.org To: linux-unionfs@vger.kernel.org Cc: linux-security-module@vger.kernel.org Cc: kernel-team@android.com --- v16 - rebase and merge of two patches. - add adjustment to deal with execv when overrides is off. v15 - Revert back to v4 with fixes from on the way from v5-v14. The single structure argument passing to address the complaints about too many arguments was rejected by the community. - Drop the udner discussion fix for an additional CAP_DAC_READ_SEARCH check. Can address that independently. - ToDo: upstream test frame for thes security fixes (currently testing is all in Android). v14: - Rejoin, rebase and a few adjustments. v13: - Pull out first patch and try to get it in alone feedback, some Acks, and then because people forgot why we were doing i. 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. Documentation/filesystems/locking.rst | 2 +- Documentation/filesystems/overlayfs.rst | 23 ++++++++++++++++ fs/9p/acl.c | 3 ++- fs/9p/xattr.c | 3 ++- fs/afs/xattr.c | 10 +++---- fs/btrfs/xattr.c | 3 ++- fs/ceph/xattr.c | 3 ++- fs/cifs/xattr.c | 2 +- fs/ecryptfs/inode.c | 6 +++-- fs/ecryptfs/mmap.c | 2 +- fs/erofs/xattr.c | 3 ++- fs/ext2/xattr_security.c | 2 +- fs/ext2/xattr_trusted.c | 2 +- fs/ext2/xattr_user.c | 2 +- fs/ext4/xattr_security.c | 2 +- fs/ext4/xattr_trusted.c | 2 +- fs/ext4/xattr_user.c | 2 +- fs/f2fs/xattr.c | 4 +-- fs/fuse/xattr.c | 4 +-- fs/gfs2/xattr.c | 3 ++- fs/hfs/attr.c | 2 +- fs/hfsplus/xattr.c | 3 ++- fs/hfsplus/xattr_security.c | 3 ++- fs/hfsplus/xattr_trusted.c | 3 ++- fs/hfsplus/xattr_user.c | 3 ++- fs/jffs2/security.c | 3 ++- fs/jffs2/xattr_trusted.c | 3 ++- fs/jffs2/xattr_user.c | 3 ++- fs/jfs/xattr.c | 5 ++-- fs/kernfs/inode.c | 3 ++- fs/nfs/nfs4proc.c | 9 ++++--- fs/ocfs2/xattr.c | 9 ++++--- fs/orangefs/xattr.c | 3 ++- fs/overlayfs/copy_up.c | 2 +- fs/overlayfs/dir.c | 17 +++++++----- fs/overlayfs/file.c | 26 +++++++++--------- fs/overlayfs/inode.c | 23 ++++++++-------- fs/overlayfs/namei.c | 6 ++--- fs/overlayfs/overlayfs.h | 5 ++-- fs/overlayfs/ovl_entry.h | 1 + fs/overlayfs/readdir.c | 8 +++--- fs/overlayfs/super.c | 34 ++++++++++++++++++----- fs/overlayfs/util.c | 13 +++++++-- fs/posix_acl.c | 2 +- fs/reiserfs/xattr_security.c | 3 ++- fs/reiserfs/xattr_trusted.c | 3 ++- fs/reiserfs/xattr_user.c | 3 ++- fs/squashfs/xattr.c | 2 +- fs/ubifs/xattr.c | 3 ++- fs/xattr.c | 36 ++++++++++++------------- fs/xfs/xfs_xattr.c | 3 ++- include/linux/xattr.h | 9 ++++--- include/uapi/linux/xattr.h | 7 +++-- mm/shmem.c | 3 ++- net/socket.c | 3 ++- security/commoncap.c | 6 +++-- security/integrity/evm/evm_main.c | 3 ++- security/selinux/hooks.c | 11 +++++--- security/smack/smack_lsm.c | 5 ++-- 59 files changed, 237 insertions(+), 135 deletions(-)