Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933991AbXFFB2I (ORCPT ); Tue, 5 Jun 2007 21:28:08 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758510AbXFFB14 (ORCPT ); Tue, 5 Jun 2007 21:27:56 -0400 Received: from e32.co.us.ibm.com ([32.97.110.150]:47220 "EHLO e32.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750837AbXFFB1z (ORCPT ); Tue, 5 Jun 2007 21:27:55 -0400 Date: Tue, 5 Jun 2007 20:27:43 -0500 From: "Serge E. Hallyn" To: Pavel Emelianov Cc: "Serge E. Hallyn" , menage@google.com, Andrew Morton , dev@sw.ru, vatsa@in.ibm.com, ebiederm@xmission.com, svaidy@linux.vnet.ibm.com, balbir@in.ibm.com, pj@sgi.com, cpw@sgi.com, ckrm-tech@lists.sourceforge.net, linux-kernel@vger.kernel.org, containers@lists.osdl.org, mbligh@google.com, rohitseth@google.com, devel@openvz.org Subject: Re: [PATCH 1/1] containers: implement nsproxy containers subsystem Message-ID: <20070606012743.GA16893@sergelap.austin.ibm.com> References: <20070604185034.GA17970@sergelap.austin.ibm.com> <4665346F.20200@openvz.org> <20070605121358.GB22230@sergelap.austin.ibm.com> <46656051.2060207@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46656051.2060207@openvz.org> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10425 Lines: 351 Quoting Pavel Emelianov (xemul@openvz.org): > Serge E. Hallyn wrote: > > Quoting Pavel Emelianov (xemul@openvz.org): > >> Serge E. Hallyn wrote: > >>> >From 190ea72d213393dd1440643b2b87b5b2128dff87 Mon Sep 17 00:00:00 2001 > >>> From: Serge E. Hallyn > >>> Date: Mon, 4 Jun 2007 14:18:52 -0400 > >>> Subject: [PATCH 1/1] containers: implement nsproxy containers subsystem > >>> > >>> When a task enters a new namespace via a clone() or unshare(), a new > >>> container is created and the task moves into it. This enables > >> I have a design question. > >> > >> How the child that has a new namespace guesses what id > >> this namespace has in containers? > > > > parse /proc/$$/container > > Ok. > > > So more likely the parent would have to grab the cloned pid of the > > child, parse /proc/$$/container, then rename the container. > > Child can happen to die before this and we'll have an orphaned > container. I mean, it will be deletable, but its name will be unknown. > > Maybe its better to get the containers id from the pid of new task? Here is a patch to do so: >From f42eeba62ec06544841070f55f6f1625c1216652 Mon Sep 17 00:00:00 2001 From: Serge E. Hallyn Date: Tue, 5 Jun 2007 10:25:05 -0400 Subject: [PATCH 1/1] containers: implement namespace tracking subsystem (v3) When a task enters a new namespace via a clone() or unshare(), a new container is created and the task moves into it. This version names containers which are automatically created using container_clone() as "node_" where pid is the pid of the unsharing or cloned process. (Thanks Pavel for the idea) This is safe because if the process unshares again, it will create /containers/(...)/node_/node_ The only possibilities (AFAICT) for a -EEXIST on unshare are 1. pid wraparound 2. a process fails an unshare, then tries again. Case 1 is unlikely enough that I ignore it (at least for now). In case 2, the node_ will be empty and can be rmdir'ed to make the subsequent unshare() succeed. Changelog: Name cloned containers as "node_". (no idea where to start versioning, calling this v3 "at random") Signed-off-by: Serge E. Hallyn --- include/linux/container_subsys.h | 6 ++ include/linux/nsproxy.h | 7 +++ init/Kconfig | 9 ++++ kernel/Makefile | 1 + kernel/container.c | 27 +++++++---- kernel/ns_container.c | 99 ++++++++++++++++++++++++++++++++++++++ kernel/nsproxy.c | 16 ++++++ 7 files changed, 155 insertions(+), 10 deletions(-) create mode 100644 kernel/ns_container.c diff --git a/include/linux/container_subsys.h b/include/linux/container_subsys.h index 8fea7cf..9861751 100644 --- a/include/linux/container_subsys.h +++ b/include/linux/container_subsys.h @@ -24,3 +24,9 @@ SUBSYS(debug) #endif /* */ + +#ifdef CONFIG_CONTAINER_NS +SUBSYS(ns) +#endif + +/* */ diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index 189e0dc..8be975b 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -54,4 +54,11 @@ static inline void exit_task_namespaces(struct task_struct *p) put_nsproxy(ns); } } + +#ifdef CONFIG_CONTAINER_NS +int ns_container_clone(struct task_struct *tsk); +#else +static inline int ns_container_clone(struct task_struct *tsk) { return 0; } +#endif + #endif diff --git a/init/Kconfig b/init/Kconfig index 5861ad9..d79c505 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -355,6 +355,15 @@ config CONTAINER_CPUACCT Provides a simple Resource Controller for monitoring the total CPU consumed by the tasks in a container +config CONTAINER_NS + bool "Namespace container subsystem" + select CONTAINERS + help + Provides a simple namespace container subsystem to + provide hierarchical naming of sets of namespaces, + for instance virtual servers and checkpoint/restart + jobs. + config PROC_PID_CPUSET bool "Include legacy /proc//cpuset file" depends on CPUSETS diff --git a/kernel/Makefile b/kernel/Makefile index f73b3d3..34f2345 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -40,6 +40,7 @@ obj-$(CONFIG_CONTAINERS) += container.o obj-$(CONFIG_CONTAINER_DEBUG) += container_debug.o obj-$(CONFIG_CPUSETS) += cpuset.o obj-$(CONFIG_CONTAINER_CPUACCT) += cpu_acct.o +obj-$(CONFIG_CONTAINER_NS) += ns_container.o obj-$(CONFIG_IKCONFIG) += configs.o obj-$(CONFIG_STOP_MACHINE) += stop_machine.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o diff --git a/kernel/container.c b/kernel/container.c index 6f80487..988cd8b 100644 --- a/kernel/container.c +++ b/kernel/container.c @@ -2302,12 +2302,6 @@ void container_exit(struct task_struct *tsk, int run_callbacks) put_css_group_taskexit(cg); } -static atomic_t namecnt; -static void get_unused_name(char *buf) -{ - sprintf(buf, "node%d", atomic_inc_return(&namecnt)); -} - /** * container_clone - duplicate the current container in the hierarchy * that the given subsystem is attached to, and move this task into @@ -2317,7 +2311,7 @@ int container_clone(struct task_struct *tsk, struct container_subsys *subsys) { struct dentry *dentry; int ret = 0; - char nodename[32]; + char nodename[MAX_CONTAINER_TYPE_NAMELEN]; struct container *parent, *child; struct inode *inode; struct css_group *cg; @@ -2340,6 +2334,9 @@ int container_clone(struct task_struct *tsk, struct container_subsys *subsys) } cg = tsk->containers; parent = task_container(tsk, subsys->subsys_id); + + snprintf(nodename, MAX_CONTAINER_TYPE_NAMELEN, "node_%d", tsk->pid); + /* Pin the hierarchy */ atomic_inc(&parent->root->sb->s_active); @@ -2348,7 +2345,6 @@ int container_clone(struct task_struct *tsk, struct container_subsys *subsys) mutex_unlock(&container_mutex); /* Now do the VFS work to create a container */ - get_unused_name(nodename); inode = parent->dentry->d_inode; /* Hold the parent directory mutex across this operation to @@ -2415,14 +2411,25 @@ int container_clone(struct task_struct *tsk, struct container_subsys *subsys) return ret; } -/* See if "cont" is a descendant of the current task's container in - * the appropriate hierarchy */ +/* + * See if "cont" is a descendant of the current task's container in + * the appropriate hierarchy + * + * If we are sending in dummytop, then presumably we are creating + * the top container in the subsystem. + * + * Called only by the ns (nsproxy) container. + */ int container_is_descendant(const struct container *cont) { int ret; struct container *target; int subsys_id; + + if (cont == dummytop) + return 1; + get_first_subsys(cont, NULL, &subsys_id); target = task_container(current, subsys_id); while (cont != target && cont!= cont->top_container) { diff --git a/kernel/ns_container.c b/kernel/ns_container.c new file mode 100644 index 0000000..3465716 --- /dev/null +++ b/kernel/ns_container.c @@ -0,0 +1,99 @@ +/* + * ns_container.c - namespace container subsystem + * + * Copyright 2006, 2007 IBM Corp + */ + +#include +#include +#include + +struct ns_container { + struct container_subsys_state css; + spinlock_t lock; +}; + +struct container_subsys ns_subsys; + +static inline struct ns_container *container_to_ns( + struct container *container) +{ + return container_of(container_subsys_state(container, ns_subsys_id), + struct ns_container, css); +} + +int ns_container_clone(struct task_struct *task) +{ + return container_clone(task, &ns_subsys); +} + +/* + * Rules: + * 1. you can only enter a container which is a child of your current + * container + * 2. you can only place another process into a container if + * a. you have CAP_SYS_ADMIN + * b. your container is an ancestor of task's destination container + * (hence either you are in the same container as task, or in an + * ancestor container thereof) + */ +static int ns_can_attach(struct container_subsys *ss, + struct container *new_container, struct task_struct *task) +{ + struct container *orig; + + if (current != task) { + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!container_is_descendant(new_container)) + return -EPERM; + } + + if (atomic_read(&new_container->count) != 0) + return -EPERM; + + orig = task_container(task, ns_subsys_id); + if (orig && orig != new_container->parent) + return -EPERM; + + return 0; +} + +/* + * Rules: you can only create a container if + * 1. you are capable(CAP_SYS_ADMIN) + * 2. the target container is a descendant of your own container + */ +static int ns_create(struct container_subsys *ss, struct container *container) +{ + struct ns_container *ns_container; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + if (!container_is_descendant(container)) + return -EPERM; + + ns_container = kzalloc(sizeof(*ns_container), GFP_KERNEL); + if (!ns_container) return -ENOMEM; + spin_lock_init(&ns_container->lock); + container->subsys[ns_subsys.subsys_id] = &ns_container->css; + return 0; +} + +static void ns_destroy(struct container_subsys *ss, + struct container *container) +{ + struct ns_container *ns_container; + + ns_container = container_to_ns(container); + kfree(ns_container); +} + +struct container_subsys ns_subsys = { + .name = "ns", + .can_attach = ns_can_attach, + .create = ns_create, + .destroy = ns_destroy, + .subsys_id = ns_subsys_id, +}; diff --git a/kernel/nsproxy.c b/kernel/nsproxy.c index 1bc4b55..afce808 100644 --- a/kernel/nsproxy.c +++ b/kernel/nsproxy.c @@ -124,7 +124,14 @@ int copy_namespaces(int flags, struct task_struct *tsk) goto out; } + err = ns_container_clone(tsk); + if (err) { + put_nsproxy(new_ns); + goto out; + } + tsk->nsproxy = new_ns; + out: put_nsproxy(old_ns); return err; @@ -177,6 +184,15 @@ int unshare_nsproxy_namespaces(unsigned long unshare_flags, if (IS_ERR(*new_nsp)) { err = PTR_ERR(*new_nsp); put_nsproxy(old_ns); + goto out; + } + + err = ns_container_clone(current); + if (err) { + put_nsproxy(*new_nsp); + put_nsproxy(old_ns); } + +out: return err; } -- 1.5.1.1.GIT - 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/