Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753214AbcDZToA (ORCPT ); Tue, 26 Apr 2016 15:44:00 -0400 Received: from mail-io0-f178.google.com ([209.85.223.178]:33369 "EHLO mail-io0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752717AbcDZThG (ORCPT ); Tue, 26 Apr 2016 15:37:06 -0400 From: Seth Forshee To: "Eric W. Biederman" , Alexander Viro Cc: Serge Hallyn , Richard Weinberger , Austin S Hemmelgarn , Miklos Szeredi , Pavel Tikhomirov , linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, cgroups@vger.kernel.org, Seth Forshee Subject: [PATCH v4 12/21] fs: Refuse uid/gid changes which don't map into s_user_ns Date: Tue, 26 Apr 2016 14:36:25 -0500 Message-Id: <1461699396-33000-13-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> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1060 Lines: 34 Add checks to inode_change_ok to verify that uid and gid changes will map into the superblock's user namespace. If they do not fail with -EOVERFLOW. This cannot be overriden with ATTR_FORCE. Signed-off-by: Seth Forshee Acked-by: Serge Hallyn --- fs/attr.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/attr.c b/fs/attr.c index 25b24d0f6c88..3cfaaac4a18e 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -42,6 +42,17 @@ int inode_change_ok(const struct inode *inode, struct iattr *attr) return error; } + /* + * Verify that uid/gid changes are valid in the target namespace + * of the superblock. This cannot be overriden using ATTR_FORCE. + */ + if (ia_valid & ATTR_UID && + from_kuid(inode->i_sb->s_user_ns, attr->ia_uid) == (uid_t)-1) + return -EOVERFLOW; + if (ia_valid & ATTR_GID && + from_kgid(inode->i_sb->s_user_ns, attr->ia_gid) == (gid_t)-1) + return -EOVERFLOW; + /* If force is set do it anyway. */ if (ia_valid & ATTR_FORCE) return 0; -- 2.7.4