From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756768Ab1BAPCb (ORCPT ); Tue, 1 Feb 2011 10:02:31 -0500 Received: from msux-gh1-uea01.nsa.gov ([63.239.65.39]:47653 "EHLO msux-gh1-uea01.nsa.gov" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751167Ab1BAPCa (ORCPT ); Tue, 1 Feb 2011 10:02:30 -0500 Subject: Re: [PATCH] security/selinux: fix /proc/sys/ labeling From: Stephen Smalley To: Lucian Adrian Grijincu Cc: James Morris , Eric Paris , Nick Piggin , "Eric W. Biederman" , linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org In-Reply-To: <1296519474-15714-1-git-send-email-lucian.grijincu@gmail.com> References: <1296519474-15714-1-git-send-email-lucian.grijincu@gmail.com> Content-Type: text/plain; charset="UTF-8" Organization: National Security Agency Date: Tue, 01 Feb 2011 10:02:18 -0500 Message-ID: <1296572538.12605.4.camel@moss-pluto> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 (2.32.1-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-02-01 at 02:17 +0200, Lucian Adrian Grijincu wrote: > From: Eric W. Biederman Is this patch really from Eric or just derived from an earlier patch by him? > > This fixes an old (2007) selinux regression: filesystem labeling for > /proc/sys returned > -r--r--r-- unknown /proc/sys/fs/file-nr > instead of > -r--r--r-- system_u:object_r:sysctl_fs_t:s0 /proc/sys/fs/file-nr > > Events that lead to breaking of /proc/sys selinux labeling: > > 1) sysctl was reimplemented to route all calls through /proc/sysctl > > commit 77b14db502cb85a031fe8fde6c85d52f3e0acb63 > [PATCH] sysctl: reimplement the sysctl proc support > > 2) proc_dir_entry was removed from ctl_table: > > commit 3fbfa98112fc3962c416452a0baf2214381030e6 > [PATCH] sysctl: remove the proc_dir_entry member for the sysctl tables > > 3) selinux still walked the proc_dir_entry tree to apply > labeling. Because ctl_tables don't have a proc_dir_entry, we did > not label /proc/sys/ inodes any more. To achieve this the /proc/sys > inodes were marked private and private inodes were ignored by > selinux. > > commit bbaca6c2e7ef0f663bc31be4dad7cf530f6c4962 > [PATCH] selinux: enhance selinux to always ignore private inodes > > commit 86a71dbd3e81e8870d0f0e56b87875f57e58222b > [PATCH] sysctl: hide the sysctl proc inodes from selinux > > Access control checks have been done by means of a special sysctl hook > that was called for read/write accesses to any /proc/sys/ entry. > > We don't have to do this because, instead of walking the > proc_dir_entry tree we can walk the dentry tree (as done in this > patch). With this patch: > * we don't mark /proc/sys inodes as private > * we don't need the sysclt security hook > * we walk the dentry tree to find the path to the inode. > > We have to strip the PID in /proc/PID/ entries that have a > proc_dir_entry because selinux does not know how to label paths like > '/1/net/rpc/nfsd.fh' (and defaults to 'proc_t' labeling). Selinux does > know of '/net/rpc/nfsd.fh' (and applies the 'sysctl_rpc_t' label). > > PID stripping from the path was done implicitly in the previous code > because the proc_dir_entry tree had the root in '/net' in the example > from above. The dentry tree has the root in '/1'. > > Signed-off-by: Eric W. Biederman And did Eric truly sign off on this patch or just on an earlier one? > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index e276eb4..7c5dfb1 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -1317,9 +1311,9 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent > > if ((sbsec->flags & SE_SBPROC) && !S_ISLNK(inode->i_mode)) { > struct proc_inode *proci = PROC_I(inode); > - if (proci->pde) { > + if (opt_dentry && (proci->pde || proci->sysctl)) { > isec->sclass = inode_mode_to_security_class(inode->i_mode); > - rc = selinux_proc_get_sid(proci->pde, > + rc = selinux_proc_get_sid(opt_dentry, > isec->sclass, > &sid); > if (rc) It would be nice if we could eliminate the last remaining piece of proc internal knowledge from this code - why do we need the proci->pde || proci->sysctl test here? What changes without it? -- Stephen Smalley National Security Agency