1/*
  2 * net/core/netclassid_cgroup.c	Classid Cgroupfs Handling
  3 *
  4 *		This program is free software; you can redistribute it and/or
  5 *		modify it under the terms of the GNU General Public License
  6 *		as published by the Free Software Foundation; either version
  7 *		2 of the License, or (at your option) any later version.
  8 *
  9 * Authors:	Thomas Graf <tgraf@suug.ch>
 10 */
 11
 12#include <linux/slab.h>
 13#include <linux/cgroup.h>
 14#include <linux/fdtable.h>
 15#include <linux/sched/task.h>
 16
 17#include <net/cls_cgroup.h>
 18#include <net/sock.h>
 19
 20static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
 21{
 22	return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
 23}
 24
 25struct cgroup_cls_state *task_cls_state(struct task_struct *p)
 26{
 27	return css_cls_state(task_css_check(p, net_cls_cgrp_id,
 28					    rcu_read_lock_bh_held()));
 29}
 30EXPORT_SYMBOL_GPL(task_cls_state);
 31
 32static struct cgroup_subsys_state *
 33cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
 34{
 35	struct cgroup_cls_state *cs;
 36
 37	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
 38	if (!cs)
 39		return ERR_PTR(-ENOMEM);
 40
 41	return &cs->css;
 42}
 43
 44static int cgrp_css_online(struct cgroup_subsys_state *css)
 45{
 46	struct cgroup_cls_state *cs = css_cls_state(css);
 47	struct cgroup_cls_state *parent = css_cls_state(css->parent);
 48
 49	if (parent)
 50		cs->classid = parent->classid;
 51
 52	return 0;
 53}
 54
 55static void cgrp_css_free(struct cgroup_subsys_state *css)
 56{
 57	kfree(css_cls_state(css));
 58}
 59
 60static int update_classid_sock(const void *v, struct file *file, unsigned n)
 61{
 62	int err;
 63	struct socket *sock = sock_from_file(file, &err);
 64
 65	if (sock) {
 66		spin_lock(&cgroup_sk_update_lock);
 67		sock_cgroup_set_classid(&sock->sk->sk_cgrp_data,
 68					(unsigned long)v);
 69		spin_unlock(&cgroup_sk_update_lock);
 70	}
 71	return 0;
 72}
 73
 74static void cgrp_attach(struct cgroup_taskset *tset)
 75{
 76	struct cgroup_subsys_state *css;
 77	struct task_struct *p;
 78
 79	cgroup_taskset_for_each(p, css, tset) {
 80		task_lock(p);
 81		iterate_fd(p->files, 0, update_classid_sock,
 82			   (void *)(unsigned long)css_cls_state(css)->classid);
 83		task_unlock(p);
 84	}
 85}
 86
 87static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
 88{
 89	return css_cls_state(css)->classid;
 90}
 91
 92static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
 93			 u64 value)
 94{
 95	struct cgroup_cls_state *cs = css_cls_state(css);
 96	struct css_task_iter it;
 97	struct task_struct *p;
 98
 99	cgroup_sk_alloc_disable();
100
101	cs->classid = (u32)value;
102
103	css_task_iter_start(css, 0, &it);
104	while ((p = css_task_iter_next(&it))) {
105		task_lock(p);
106		iterate_fd(p->files, 0, update_classid_sock,
107			   (void *)(unsigned long)cs->classid);
108		task_unlock(p);
109	}
110	css_task_iter_end(&it);
111
112	return 0;
113}
114
115static struct cftype ss_files[] = {
116	{
117		.name		= "classid",
118		.read_u64	= read_classid,
119		.write_u64	= write_classid,
120	},
121	{ }	/* terminate */
122};
123
124struct cgroup_subsys net_cls_cgrp_subsys = {
125	.css_alloc		= cgrp_css_alloc,
126	.css_online		= cgrp_css_online,
127	.css_free		= cgrp_css_free,
128	.attach			= cgrp_attach,
129	.legacy_cftypes		= ss_files,
130};