1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * net/core/netclassid_cgroup.c	Classid Cgroupfs Handling
  4 *
  5 * Authors:	Thomas Graf <tgraf@suug.ch>
  6 */
  7
  8#include <linux/slab.h>
  9#include <linux/cgroup.h>
 10#include <linux/fdtable.h>
 11#include <linux/sched/task.h>
 12
 13#include <net/cls_cgroup.h>
 14#include <net/sock.h>
 15
 16static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
 17{
 18	return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
 19}
 20
 21struct cgroup_cls_state *task_cls_state(struct task_struct *p)
 22{
 23	return css_cls_state(task_css_check(p, net_cls_cgrp_id,
 24					    rcu_read_lock_bh_held()));
 25}
 26EXPORT_SYMBOL_GPL(task_cls_state);
 27
 28static struct cgroup_subsys_state *
 29cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
 30{
 31	struct cgroup_cls_state *cs;
 32
 33	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 34	if (!cs)
 35		return ERR_PTR(-ENOMEM);
 36
 37	return &cs->css;
 38}
 39
 40static int cgrp_css_online(struct cgroup_subsys_state *css)
 41{
 42	struct cgroup_cls_state *cs = css_cls_state(css);
 43	struct cgroup_cls_state *parent = css_cls_state(css->parent);
 44
 45	if (parent)
 46		cs->classid = parent->classid;
 47
 48	return 0;
 49}
 50
 51static void cgrp_css_free(struct cgroup_subsys_state *css)
 52{
 53	kfree(css_cls_state(css));
 54}
 55
 56static int update_classid_sock(const void *v, struct file *file, unsigned n)
 57{
 58	int err;
 59	struct socket *sock = sock_from_file(file, &err);
 60
 61	if (sock) {
 62		spin_lock(&cgroup_sk_update_lock);
 63		sock_cgroup_set_classid(&sock->sk->sk_cgrp_data,
 64					(unsigned long)v);
 65		spin_unlock(&cgroup_sk_update_lock);
 66	}
 67	return 0;
 68}
 69
 70static void cgrp_attach(struct cgroup_taskset *tset)
 71{
 72	struct cgroup_subsys_state *css;
 73	struct task_struct *p;
 74
 75	cgroup_taskset_for_each(p, css, tset) {
 76		task_lock(p);
 77		iterate_fd(p->files, 0, update_classid_sock,
 78			   (void *)(unsigned long)css_cls_state(css)->classid);
 79		task_unlock(p);
 80	}
 81}
 82
 83static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
 84{
 85	return css_cls_state(css)->classid;
 86}
 87
 88static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
 89			 u64 value)
 90{
 91	struct cgroup_cls_state *cs = css_cls_state(css);
 92	struct css_task_iter it;
 93	struct task_struct *p;
 94
 95	cgroup_sk_alloc_disable();
 96
 97	cs->classid = (u32)value;
 98
 99	css_task_iter_start(css, 0, &it);
100	while ((p = css_task_iter_next(&it))) {
101		task_lock(p);
102		iterate_fd(p->files, 0, update_classid_sock,
103			   (void *)(unsigned long)cs->classid);
104		task_unlock(p);
105		cond_resched();
106	}
107	css_task_iter_end(&it);
108
109	return 0;
110}
111
112static struct cftype ss_files[] = {
113	{
114		.name		= "classid",
115		.read_u64	= read_classid,
116		.write_u64	= write_classid,
117	},
118	{ }	/* terminate */
119};
120
121struct cgroup_subsys net_cls_cgrp_subsys = {
122	.css_alloc		= cgrp_css_alloc,
123	.css_online		= cgrp_css_online,
124	.css_free		= cgrp_css_free,
125	.attach			= cgrp_attach,
126	.legacy_cftypes		= ss_files,
127};