Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758613AbZCQSX6 (ORCPT ); Tue, 17 Mar 2009 14:23:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754166AbZCQSXs (ORCPT ); Tue, 17 Mar 2009 14:23:48 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:39056 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753582AbZCQSXr (ORCPT ); Tue, 17 Mar 2009 14:23:47 -0400 Date: Tue, 17 Mar 2009 13:23:35 -0500 From: "Serge E. Hallyn" To: Stephen Smalley Cc: Igor Zhbanov , "J. Bruce Fields" , Michael Kerrisk , linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, neilb@suse.de, Trond.Myklebust@netapp.com, David Howells , Andrew Morgan , James Morris , linux-security-module@vger.kernel.org, SELinux Subject: Re: =?utf-8?B?0J7RgtCy0LXRgjogVkZTLCBORlMg?= =?utf-8?Q?security_bug=3F_Shoul?= =?utf-8?Q?d?= CAP_MKNOD and CAP_LINUX_IMMUTABLE be added to CAP_FS_MASK? Message-ID: <20090317182335.GB31633@us.ibm.com> References: <20090313175848.GB27891@fieldses.org> <20090313190002.GA16025@us.ibm.com> <1237227705.1035.93.camel@localhost.localdomain> <20090316184926.GA6729@us.ibm.com> <1237237216.1035.195.camel@localhost.localdomain> <20090316231340.GC15522@us.ibm.com> <1237299633.6582.107.camel@localhost.localdomain> <20090317173903.GA31566@us.ibm.com> <1237312345.6582.140.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1237312345.6582.140.camel@localhost.localdomain> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2906 Lines: 69 Quoting Stephen Smalley (sds@tycho.nsa.gov): > On Tue, 2009-03-17 at 12:39 -0500, Serge E. Hallyn wrote: > > Quoting Stephen Smalley (sds@tycho.nsa.gov): > > > > So do you think it makes sense to have CAP_MAC_ADMIN and CAP_FOWNER > > > > in CAP_FS_MASK? In other words are you objecting to CAP_SYS_ADMIN > > > > because of all of its other implications, or because you disagree > > > > that labels for security modules should be treated as mere fs data > > > > here? > > > > > > For CAP_FOWNER, yes (and it is already there). CAP_MAC_ADMIN is less > > > > Sorry, I meant CAP_SETFCAP. Should it be added? > > Sure - it is only used for filesystem operations. Ok, so then: > > > > ideal as it isn't clearly tied to filesystem accesses, and likewise for > > > CAP_MAC_OVERRIDE (but that one is included in CAP_FS_MASK already). > > > > So it is. I didn't realize that. > > > > > Ideally the capability space would be partitioned into capabilities that > > > affect filesystem accesses and the rest so that setfsuid() would yield > > > the expected behavior of only affecting filesystem access. > > > CAP_SYS_ADMIN is even less suitable due to its pervasive use outside of > > > the filesystem. So that's the first concern. > > > > > > The second one is that we don't want CAP_SYS_ADMIN (or CAP_MAC_ADMIN) to > > > be required when setting SELinux labels. Only the SELinux permission > > > checks should govern setting those labels (aside from the usual DAC > > > ownership || CAP_FOWNER check). > > > > So if a non-selinux kernel is booted, then you think only the usual > > DAC checks should be required to set selinux labels? > > I'm talking about the dumb NFS server case (non-SELinux NFS server > providing label and data storage to SELinux clients, MAC enforcement > handled client-side). But we aren't there yet, so I don't think we have > to worry about it right now. But in cap_inode_setxattr, any security.* xattrs are controlled by CAP_SYS_ADMIN. So do you think that this should be changed to a CAP_XATTR_SECURITY capability which can be added to CAP_FS_MASK? Or do you think it's ok that fsuid=0 does not allow you to set security.selinux (or security.SMACK64, etc) xattrs when selinux is not compiled in? (You may have already answered this with your EOPNOTSUPP comment, but I want to make sure I understand right) > > Does anyone know what the trusted xattrs are used for? > > Not beyond what attr(5) says about them. Well, if attr(5) says CAP_SYS_ADMIN being needed is the very thing that defines these xattrs, then changing that seems a bigger deal. That really does seem akin to changing kernel-user API. thanks, -serge -- 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/