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// SPDX-License-Identifier: GPL-2.0
#include "cgroup-internal.h"
#include <linux/sched/task.h>
#include <linux/slab.h>
#include <linux/nsproxy.h>
#include <linux/proc_ns.h>
/* cgroup namespaces */
static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
{
return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
}
static void dec_cgroup_namespaces(struct ucounts *ucounts)
{
dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
}
static struct cgroup_namespace *alloc_cgroup_ns(void)
{
struct cgroup_namespace *new_ns;
int ret;
new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
if (!new_ns)
return ERR_PTR(-ENOMEM);
ret = ns_alloc_inum(&new_ns->ns);
if (ret) {
kfree(new_ns);
return ERR_PTR(ret);
}
refcount_set(&new_ns->ns.count, 1);
new_ns->ns.ops = &cgroupns_operations;
return new_ns;
}
void free_cgroup_ns(struct cgroup_namespace *ns)
{
put_css_set(ns->root_cset);
dec_cgroup_namespaces(ns->ucounts);
put_user_ns(ns->user_ns);
ns_free_inum(&ns->ns);
kfree(ns);
}
EXPORT_SYMBOL(free_cgroup_ns);
struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
struct user_namespace *user_ns,
struct cgroup_namespace *old_ns)
{
struct cgroup_namespace *new_ns;
struct ucounts *ucounts;
struct css_set *cset;
BUG_ON(!old_ns);
if (!(flags & CLONE_NEWCGROUP)) {
get_cgroup_ns(old_ns);
return old_ns;
}
/* Allow only sysadmin to create cgroup namespace. */
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
ucounts = inc_cgroup_namespaces(user_ns);
if (!ucounts)
return ERR_PTR(-ENOSPC);
/* It is not safe to take cgroup_mutex here */
spin_lock_irq(&css_set_lock);
cset = task_css_set(current);
get_css_set(cset);
spin_unlock_irq(&css_set_lock);
new_ns = alloc_cgroup_ns();
if (IS_ERR(new_ns)) {
put_css_set(cset);
dec_cgroup_namespaces(ucounts);
return new_ns;
}
new_ns->user_ns = get_user_ns(user_ns);
new_ns->ucounts = ucounts;
new_ns->root_cset = cset;
return new_ns;
}
static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
{
return container_of(ns, struct cgroup_namespace, ns);
}
static int cgroupns_install(struct nsset *nsset, struct ns_common *ns)
{
struct nsproxy *nsproxy = nsset->nsproxy;
struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
if (!ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN) ||
!ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
return -EPERM;
/* Don't need to do anything if we are attaching to our own cgroupns. */
if (cgroup_ns == nsproxy->cgroup_ns)
return 0;
get_cgroup_ns(cgroup_ns);
put_cgroup_ns(nsproxy->cgroup_ns);
nsproxy->cgroup_ns = cgroup_ns;
return 0;
}
static struct ns_common *cgroupns_get(struct task_struct *task)
{
struct cgroup_namespace *ns = NULL;
struct nsproxy *nsproxy;
task_lock(task);
nsproxy = task->nsproxy;
if (nsproxy) {
ns = nsproxy->cgroup_ns;
get_cgroup_ns(ns);
}
task_unlock(task);
return ns ? &ns->ns : NULL;
}
static void cgroupns_put(struct ns_common *ns)
{
put_cgroup_ns(to_cg_ns(ns));
}
static struct user_namespace *cgroupns_owner(struct ns_common *ns)
{
return to_cg_ns(ns)->user_ns;
}
const struct proc_ns_operations cgroupns_operations = {
.name = "cgroup",
.type = CLONE_NEWCGROUP,
.get = cgroupns_get,
.put = cgroupns_put,
.install = cgroupns_install,
.owner = cgroupns_owner,
};
static __init int cgroup_namespaces_init(void)
{
return 0;
}
subsys_initcall(cgroup_namespaces_init);
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