xref: /openbmc/linux/net/core/netclassid_cgroup.c (revision 4f6cce39) 
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 
20 static 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 
25 struct 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 }
30 EXPORT_SYMBOL_GPL(task_cls_state);
31 
32 static struct cgroup_subsys_state *
33 cgrp_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 
44 static 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 
55 static void cgrp_css_free(struct cgroup_subsys_state *css)
56 {
57 	kfree(css_cls_state(css));
58 }
59 
60 static 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 
74 static void update_classid(struct cgroup_subsys_state *css, void *v)
75 {
76 	struct css_task_iter it;
77 	struct task_struct *p;
78 
79 	css_task_iter_start(css, &it);
80 	while ((p = css_task_iter_next(&it))) {
81 		task_lock(p);
82 		iterate_fd(p->files, 0, update_classid_sock, v);
83 		task_unlock(p);
84 	}
85 	css_task_iter_end(&it);
86 }
87 
88 static void cgrp_attach(struct cgroup_taskset *tset)
89 {
90 	struct cgroup_subsys_state *css;
91 
92 	cgroup_taskset_first(tset, &css);
93 	update_classid(css,
94 		       (void *)(unsigned long)css_cls_state(css)->classid);
95 }
96 
97 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
98 {
99 	return css_cls_state(css)->classid;
100 }
101 
102 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
103 			 u64 value)
104 {
105 	struct cgroup_cls_state *cs = css_cls_state(css);
106 
107 	cgroup_sk_alloc_disable();
108 
109 	cs->classid = (u32)value;
110 
111 	update_classid(css, (void *)(unsigned long)cs->classid);
112 	return 0;
113 }
114 
115 static struct cftype ss_files[] = {
116 	{
117 		.name		= "classid",
118 		.read_u64	= read_classid,
119 		.write_u64	= write_classid,
120 	},
121 	{ }	/* terminate */
122 };
123 
124 struct 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 };
131