Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756377AbbLDR1n (ORCPT ); Fri, 4 Dec 2015 12:27:43 -0500 Received: from h2.hallyn.com ([78.46.35.8]:42447 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754610AbbLDR1l (ORCPT ); Fri, 4 Dec 2015 12:27:41 -0500 Date: Fri, 4 Dec 2015 11:27:38 -0600 From: "Serge E. Hallyn" To: Seth Forshee Cc: "Eric W. Biederman" , Alexander Viro , Serge Hallyn , Richard Weinberger , Austin S Hemmelgarn , Miklos Szeredi , linux-bcache@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-kernel@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 Subject: Re: [PATCH 09/19] fs: Refuse uid/gid changes which don't map into s_user_ns Message-ID: <20151204172738.GA2280@mail.hallyn.com> References: <1449070821-73820-1-git-send-email-seth.forshee@canonical.com> <1449070821-73820-10-git-send-email-seth.forshee@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1449070821-73820-10-git-send-email-seth.forshee@canonical.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1832 Lines: 51 On Wed, Dec 02, 2015 at 09:40:09AM -0600, Seth Forshee wrote: > 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 ... although i could see root on the host being upset that it can't assign a uid not valid in the mounter's ns. But it does seem safer. > --- > fs/attr.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/fs/attr.c b/fs/attr.c > index 6530ced19697..55b46e3aa888 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; > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/