forked from luck/tmp_suning_uos_patched
858d72ead4
When a task enters a new namespace via a clone() or unshare(), a new cgroup is created and the task moves into it. This version names cgroups which are automatically created using cgroup_clone() as "node_<pid>" 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 /cgroups/(...)/node_<pid>/node_<pid> 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_<pid> will be empty and can be rmdir'ed to make the subsequent unshare() succeed. Changelog: Name cloned cgroups as "node_<pid>". [clg@fr.ibm.com: fix order of cgroup subsystems in init/Kconfig] Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Cc: Paul Menage <menage@google.com> Signed-off-by: Cedric Le Goater <clg@fr.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
101 lines
2.2 KiB
C
101 lines
2.2 KiB
C
/*
|
|
* ns_cgroup.c - namespace cgroup subsystem
|
|
*
|
|
* Copyright 2006, 2007 IBM Corp
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/cgroup.h>
|
|
#include <linux/fs.h>
|
|
|
|
struct ns_cgroup {
|
|
struct cgroup_subsys_state css;
|
|
spinlock_t lock;
|
|
};
|
|
|
|
struct cgroup_subsys ns_subsys;
|
|
|
|
static inline struct ns_cgroup *cgroup_to_ns(
|
|
struct cgroup *cgroup)
|
|
{
|
|
return container_of(cgroup_subsys_state(cgroup, ns_subsys_id),
|
|
struct ns_cgroup, css);
|
|
}
|
|
|
|
int ns_cgroup_clone(struct task_struct *task)
|
|
{
|
|
return cgroup_clone(task, &ns_subsys);
|
|
}
|
|
|
|
/*
|
|
* Rules:
|
|
* 1. you can only enter a cgroup which is a child of your current
|
|
* cgroup
|
|
* 2. you can only place another process into a cgroup if
|
|
* a. you have CAP_SYS_ADMIN
|
|
* b. your cgroup is an ancestor of task's destination cgroup
|
|
* (hence either you are in the same cgroup as task, or in an
|
|
* ancestor cgroup thereof)
|
|
*/
|
|
static int ns_can_attach(struct cgroup_subsys *ss,
|
|
struct cgroup *new_cgroup, struct task_struct *task)
|
|
{
|
|
struct cgroup *orig;
|
|
|
|
if (current != task) {
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
if (!cgroup_is_descendant(new_cgroup))
|
|
return -EPERM;
|
|
}
|
|
|
|
if (atomic_read(&new_cgroup->count) != 0)
|
|
return -EPERM;
|
|
|
|
orig = task_cgroup(task, ns_subsys_id);
|
|
if (orig && orig != new_cgroup->parent)
|
|
return -EPERM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Rules: you can only create a cgroup if
|
|
* 1. you are capable(CAP_SYS_ADMIN)
|
|
* 2. the target cgroup is a descendant of your own cgroup
|
|
*/
|
|
static struct cgroup_subsys_state *ns_create(struct cgroup_subsys *ss,
|
|
struct cgroup *cgroup)
|
|
{
|
|
struct ns_cgroup *ns_cgroup;
|
|
|
|
if (!capable(CAP_SYS_ADMIN))
|
|
return ERR_PTR(-EPERM);
|
|
if (!cgroup_is_descendant(cgroup))
|
|
return ERR_PTR(-EPERM);
|
|
|
|
ns_cgroup = kzalloc(sizeof(*ns_cgroup), GFP_KERNEL);
|
|
if (!ns_cgroup)
|
|
return ERR_PTR(-ENOMEM);
|
|
spin_lock_init(&ns_cgroup->lock);
|
|
return &ns_cgroup->css;
|
|
}
|
|
|
|
static void ns_destroy(struct cgroup_subsys *ss,
|
|
struct cgroup *cgroup)
|
|
{
|
|
struct ns_cgroup *ns_cgroup;
|
|
|
|
ns_cgroup = cgroup_to_ns(cgroup);
|
|
kfree(ns_cgroup);
|
|
}
|
|
|
|
struct cgroup_subsys ns_subsys = {
|
|
.name = "ns",
|
|
.can_attach = ns_can_attach,
|
|
.create = ns_create,
|
|
.destroy = ns_destroy,
|
|
.subsys_id = ns_subsys_id,
|
|
};
|