From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:59438 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755978AbeDKSrp (ORCPT ); Wed, 11 Apr 2018 14:47:45 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miklos Szeredi , Sasha Levin Subject: [PATCH 4.4 096/190] ovl: filter trusted xattr for non-admin Date: Wed, 11 Apr 2018 20:35:42 +0200 Message-Id: <20180411183556.186437172@linuxfoundation.org> In-Reply-To: <20180411183550.114495991@linuxfoundation.org> References: <20180411183550.114495991@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miklos Szeredi [ Upstream commit a082c6f680da298cf075886ff032f32ccb7c5e1a ] Filesystems filter out extended attributes in the "trusted." domain for unprivlieged callers. Overlay calls underlying filesystem's method with elevated privs, so need to do the filtering in overlayfs too. Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/inode.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -272,6 +272,16 @@ ssize_t ovl_getxattr(struct dentry *dent return vfs_getxattr(realpath.dentry, name, value, size); } +static bool ovl_can_list(const char *s) +{ + /* List all non-trusted xatts */ + if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0) + return true; + + /* Never list trusted.overlay, list other trusted for superuser only */ + return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); +} + ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) { struct path realpath; @@ -296,7 +306,7 @@ ssize_t ovl_listxattr(struct dentry *den return -EIO; len -= slen; - if (ovl_is_private_xattr(s)) { + if (!ovl_can_list(s)) { res -= slen; memmove(s, s + slen, len); } else {