From patchwork Fri Jul 29 17:27:48 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Serge E. Hallyn" X-Patchwork-Id: 107443 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id B5832B6F64 for ; Sat, 30 Jul 2011 03:29:10 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751997Ab1G2R1r (ORCPT ); Fri, 29 Jul 2011 13:27:47 -0400 Received: from 50-56-35-84.static.cloud-ips.com ([50.56.35.84]:47797 "EHLO mail" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751392Ab1G2R1q (ORCPT ); Fri, 29 Jul 2011 13:27:46 -0400 Received: by mail (Postfix, from userid 1000) id 33627100252; Fri, 29 Jul 2011 17:27:48 +0000 (UTC) Date: Fri, 29 Jul 2011 17:27:48 +0000 From: "Serge E. Hallyn" To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, containers@lists.linux-foundation.org, dhowells@redhat.com Subject: [PATCH 02/14] allow root in container to copy namespaces (v3) Message-ID: <20110729172748.GB18935@hallyn.com> References: <1311706717-7398-1-git-send-email-serge@hallyn.com> <1311706717-7398-3-git-send-email-serge@hallyn.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Quoting Eric W. Biederman (ebiederm@xmission.com): > Serge Hallyn writes: > > > From: Serge E. Hallyn > > > > Othewise nested containers with user namespaces won't be possible. > > > > It's true that user namespaces are not yet fully isolated, but for > > that same reason there are far worse things that root in a child > > user ns can do. Spawning a child user ns is not in itself bad. > > > > This patch also allows setns for root in a container: > > @Eric Biederman: are there gotchas in allowing setns from child > > userns? > > Yes. We need to ensure that the target namespaces are namespaces > that have been created in from user_namespace or from a child of this > user_namespace. > > Aka we need to ensure that we have CAP_SYS_ADMIN for the new namespace. [New patch below] Othewise nested containers with user namespaces won't be possible. It's true that user namespaces are not yet fully isolated, but for that same reason there are far worse things that root in a child user ns can do. Spawning a child user ns is not in itself bad. This patch also allows setns for root in a container: @Eric Biederman: are there gotchas in allowing setns from child userns? Changelog: Jul 29: setns: target capability check for setns When changing to another namespace, make sure that we have the CAP_SYS_ADMIN capability targeted at the user namespace owning the new ns. Signed-off-by: Serge E. Hallyn Cc: Eric W. Biederman --- ipc/namespace.c | 3 +++ kernel/fork.c | 4 ++-- kernel/nsproxy.c | 7 ++----- kernel/utsname.c | 3 +++ net/core/net_namespace.c | 3 +++ 5 files changed, 13 insertions(+), 7 deletions(-) diff --git a/ipc/namespace.c b/ipc/namespace.c index ce0a647..f527e49 100644 --- a/ipc/namespace.c +++ b/ipc/namespace.c @@ -163,6 +163,9 @@ static void ipcns_put(void *ns) static int ipcns_install(struct nsproxy *nsproxy, void *ns) { + struct ipc_namespace *newns = ns; + if (!ns_capable(newns->user_ns, CAP_SYS_ADMIN)) + return -1; /* Ditch state from the old ipc namespace */ exit_sem(current); put_ipc_ns(nsproxy->ipc_ns); diff --git a/kernel/fork.c b/kernel/fork.c index e7ceaca..f9fac70 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1488,8 +1488,8 @@ long do_fork(unsigned long clone_flags, /* hopefully this check will go away when userns support is * complete */ - if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) || - !capable(CAP_SETGID)) + if (!nsown_capable(CAP_SYS_ADMIN) || !nsown_capable(CAP_SETUID) || + !nsown_capable(CAP_SETGID)) return -EPERM; } diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 9aeab4b..cadcee0 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -134,7 +134,7 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk) CLONE_NEWPID | CLONE_NEWNET))) return 0; - if (!capable(CAP_SYS_ADMIN)) { + if (!nsown_capable(CAP_SYS_ADMIN)) { err = -EPERM; goto out; } @@ -191,7 +191,7 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags, CLONE_NEWNET))) return 0; - if (!capable(CAP_SYS_ADMIN)) + if (!nsown_capable(CAP_SYS_ADMIN)) return -EPERM; *new_nsp = create_new_namespaces(unshare_flags, current, @@ -241,9 +241,6 @@ SYSCALL_DEFINE2(setns, int, fd, int, nstype) struct file *file; int err; - if (!capable(CAP_SYS_ADMIN)) - return -EPERM; - file = proc_ns_fget(fd); if (IS_ERR(file)) return PTR_ERR(file); diff --git a/kernel/utsname.c b/kernel/utsname.c index bff131b..8f648cc 100644 --- a/kernel/utsname.c +++ b/kernel/utsname.c @@ -104,6 +104,9 @@ static void utsns_put(void *ns) static int utsns_install(struct nsproxy *nsproxy, void *ns) { + struct uts_namespace *newns = ns; + if (!ns_capable(newns->user_ns, CAP_SYS_ADMIN)) + return -1; get_uts_ns(ns); put_uts_ns(nsproxy->uts_ns); nsproxy->uts_ns = ns; diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c index 5bbdbf0..90c97f6 100644 --- a/net/core/net_namespace.c +++ b/net/core/net_namespace.c @@ -620,6 +620,9 @@ static void netns_put(void *ns) static int netns_install(struct nsproxy *nsproxy, void *ns) { + struct net *net = ns; + if (!ns_capable(net->user_ns, CAP_SYS_ADMIN)) + return -1; put_net(nsproxy->net_ns); nsproxy->net_ns = get_net(ns); return 0;