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