Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750804AbXAOPDx (ORCPT ); Mon, 15 Jan 2007 10:03:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750814AbXAOPDx (ORCPT ); Mon, 15 Jan 2007 10:03:53 -0500 Received: from mtagate3.uk.ibm.com ([195.212.29.136]:25977 "EHLO mtagate3.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750804AbXAOPDw (ORCPT ); Mon, 15 Jan 2007 10:03:52 -0500 Message-ID: <45AB97D5.6010503@fr.ibm.com> Date: Mon, 15 Jan 2007 16:03:49 +0100 From: Cedric Le Goater User-Agent: Thunderbird 1.5.0.9 (X11/20061219) MIME-Version: 1.0 To: "Serge E. Hallyn" CC: Andrew Morton , lkml Subject: Re: [PATCH -mm 7/8] user_ns: handle file sigio References: <20070104180635.GA11377@sergelap.austin.ibm.com> <20070104181257.GH11377@sergelap.austin.ibm.com> <20070111212039.68e57e65.akpm@osdl.org> <20070115072653.GA7385@sergelap.austin.ibm.com> In-Reply-To: <20070115072653.GA7385@sergelap.austin.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2071 Lines: 59 Serge E. Hallyn wrote: > Quoting Andrew Morton (akpm@osdl.org): >> On Thu, 4 Jan 2007 12:12:57 -0600 >> "Serge E. Hallyn" wrote: >> >>> A process in one user namespace could set a fowner and sigio on a file in a >>> shared vfsmount, ending up killing a task in another user namespace. >>> >>> Prevent this by adding a user namespace pointer to the fown_struct, and >>> enforcing that a process causing a signal to be sent be in the same >>> user namespace as the file owner. >> This patch breaks the X server (stock FC5 install) with CONFIG_USER_NS=n. >> Neither the USB mouse nor the trackpad work. They work OK under GPM. >> >> Setting CONFIG_USER_NS=y "fixes" this. This bug was not observed in >> 2.6.20-rc3-mm1 because that kernel had user-ns-always-on.patch for other >> reasons. (I'll restore that patch). >> >> There's nothing very interesting here: > [ ... ] > > I can't see any reason for this in the code or comparative ltp runs. > Cedric is testing on a fc6 laptop, hopefully he can reproduce it. I did reproduce it on a FC5 desktop finally. get_user_ns() returns NULL when CONFIG_USER_NS=n and this breaks sigio_perm() which does not expect NULL values for ->user_ns. I would fix this with the following patch. C. Signed-off-by: Cedric Le Goater --- include/linux/user_namespace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: 2.6.20-rc4-mm1/include/linux/user_namespace.h =================================================================== --- 2.6.20-rc4-mm1.orig/include/linux/user_namespace.h +++ 2.6.20-rc4-mm1/include/linux/user_namespace.h @@ -49,7 +49,7 @@ static inline struct user_namespace *get_user_ns(struct user_namespace *ns) { - return NULL; + return &init_user_ns; } static inline int unshare_user_ns(unsigned long flags, - 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/