From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gao feng Subject: Re: Interaction user namespace, /proc/1 ownership & cap_set Date: Tue, 02 Jul 2013 18:07:05 +0800 Message-ID: <51D2A649.9030102@cn.fujitsu.com> References: <20130701161625.GQ15954@redhat.com> <51D261D3.3030002@cn.fujitsu.com> <87wqp9uz9a.fsf@xmission.com> <51D295C5.1080003@nod.at> <20130702092554.GD2524@redhat.com> <87ehbhthbl.fsf@xmission.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87ehbhthbl.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Eric W. Biederman" Cc: Richard Weinberger , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Serge Hallyn List-Id: containers.vger.kernel.org On 07/02/2013 05:57 PM, Eric W. Biederman wrote: > "Daniel P. Berrange" writes: > >> On Tue, Jul 02, 2013 at 10:56:37AM +0200, Richard Weinberger wrote: >>> Am 02.07.2013 10:44, schrieb Eric W. Biederman: >>>> Gao feng writes: >>>> >>>>> On 07/02/2013 12:16 AM, Daniel P. Berrange wrote: >>>>>> I'm struggling debugging a strange problem with interaction between user >>>>>> namespaces, cap_set and ownership of files in /proc/1/ >>>>>> >>>>> >>>>> This problem is occured after we call setuid/gid. >>>>> >>>>> for example, a task whose pid is 1234 calls >>>>> setregid(10,10); >>>>> setreuid(10,10); >> >> If seems to get reset to the right values (0:0) when we execve() >> the init binary though. This doesn't happen if we have invoked >> the capset() syscall in between the setregid & the execve() calls. > > Yes, execve() should reset the dumpable state. > > I took a quick look and I don't see a way around set_dumpable calls in > setup_new_exec. Why the process remains undumpable after exec is worth > investigating. That logic should not be user namespace specific > however. > I think it's the install_exec_creds, it calls commit_creds to set process undumpable /* dumpability changes */ if (!uid_eq(old->euid, new->euid) || !gid_eq(old->egid, new->egid) || !uid_eq(old->fsuid, new->fsuid) || !gid_eq(old->fsgid, new->fsgid) || !cred_cap_issubset(old, new)) { if (task->mm) set_dumpable(task->mm, suid_dumpable); task->pdeath_signal = 0; smp_wmb(); }