xref: /openbmc/linux/net/core/netclassid_cgroup.c (revision 293d5b43) 
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 <net/cls_cgroup.h>
16 #include <net/sock.h>
17 
18 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css)
19 {
20 	return css ? container_of(css, struct cgroup_cls_state, css) : NULL;
21 }
22 
23 struct cgroup_cls_state *task_cls_state(struct task_struct *p)
24 {
25 	return css_cls_state(task_css_check(p, net_cls_cgrp_id,
26 					    rcu_read_lock_bh_held()));
27 }
28 EXPORT_SYMBOL_GPL(task_cls_state);
29 
30 static struct cgroup_subsys_state *
31 cgrp_css_alloc(struct cgroup_subsys_state *parent_css)
32 {
33 	struct cgroup_cls_state *cs;
34 
35 	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
36 	if (!cs)
37 		return ERR_PTR(-ENOMEM);
38 
39 	return &cs->css;
40 }
41 
42 static int cgrp_css_online(struct cgroup_subsys_state *css)
43 {
44 	struct cgroup_cls_state *cs = css_cls_state(css);
45 	struct cgroup_cls_state *parent = css_cls_state(css->parent);
46 
47 	if (parent)
48 		cs->classid = parent->classid;
49 
50 	return 0;
51 }
52 
53 static void cgrp_css_free(struct cgroup_subsys_state *css)
54 {
55 	kfree(css_cls_state(css));
56 }
57 
58 static int update_classid_sock(const void *v, struct file *file, unsigned n)
59 {
60 	int err;
61 	struct socket *sock = sock_from_file(file, &err);
62 
63 	if (sock) {
64 		spin_lock(&cgroup_sk_update_lock);
65 		sock_cgroup_set_classid(&sock->sk->sk_cgrp_data,
66 					(unsigned long)v);
67 		spin_unlock(&cgroup_sk_update_lock);
68 	}
69 	return 0;
70 }
71 
72 static void update_classid(struct cgroup_subsys_state *css, void *v)
73 {
74 	struct css_task_iter it;
75 	struct task_struct *p;
76 
77 	css_task_iter_start(css, &it);
78 	while ((p = css_task_iter_next(&it))) {
79 		task_lock(p);
80 		iterate_fd(p->files, 0, update_classid_sock, v);
81 		task_unlock(p);
82 	}
83 	css_task_iter_end(&it);
84 }
85 
86 static void cgrp_attach(struct cgroup_taskset *tset)
87 {
88 	struct cgroup_subsys_state *css;
89 
90 	cgroup_taskset_first(tset, &css);
91 	update_classid(css,
92 		       (void *)(unsigned long)css_cls_state(css)->classid);
93 }
94 
95 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft)
96 {
97 	return css_cls_state(css)->classid;
98 }
99 
100 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft,
101 			 u64 value)
102 {
103 	struct cgroup_cls_state *cs = css_cls_state(css);
104 
105 	cgroup_sk_alloc_disable();
106 
107 	cs->classid = (u32)value;
108 
109 	update_classid(css, (void *)(unsigned long)cs->classid);
110 	return 0;
111 }
112 
113 static struct cftype ss_files[] = {
114 	{
115 		.name		= "classid",
116 		.read_u64	= read_classid,
117 		.write_u64	= write_classid,
118 	},
119 	{ }	/* terminate */
120 };
121 
122 struct cgroup_subsys net_cls_cgrp_subsys = {
123 	.css_alloc		= cgrp_css_alloc,
124 	.css_online		= cgrp_css_online,
125 	.css_free		= cgrp_css_free,
126 	.attach			= cgrp_attach,
127 	.legacy_cftypes		= ss_files,
128 };
129