1 /*
2  * cls_cgroup.h			Control Group Classifier
3  *
4  * Authors:	Thomas Graf <tgraf@suug.ch>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  */
12 
13 #ifndef _NET_CLS_CGROUP_H
14 #define _NET_CLS_CGROUP_H
15 
16 #include <linux/cgroup.h>
17 #include <linux/hardirq.h>
18 #include <linux/rcupdate.h>
19 #include <net/sock.h>
20 #include <net/inet_sock.h>
21 
22 #ifdef CONFIG_CGROUP_NET_CLASSID
23 struct cgroup_cls_state {
24 	struct cgroup_subsys_state css;
25 	u32 classid;
26 };
27 
28 struct cgroup_cls_state *task_cls_state(struct task_struct *p);
29 
task_cls_classid(struct task_struct * p)30 static inline u32 task_cls_classid(struct task_struct *p)
31 {
32 	u32 classid;
33 
34 	if (in_interrupt())
35 		return 0;
36 
37 	rcu_read_lock();
38 	classid = container_of(task_css(p, net_cls_cgrp_id),
39 			       struct cgroup_cls_state, css)->classid;
40 	rcu_read_unlock();
41 
42 	return classid;
43 }
44 
sock_update_classid(struct sock_cgroup_data * skcd)45 static inline void sock_update_classid(struct sock_cgroup_data *skcd)
46 {
47 	u32 classid;
48 
49 	classid = task_cls_classid(current);
50 	sock_cgroup_set_classid(skcd, classid);
51 }
52 
task_get_classid(const struct sk_buff * skb)53 static inline u32 task_get_classid(const struct sk_buff *skb)
54 {
55 	u32 classid = task_cls_state(current)->classid;
56 
57 	/* Due to the nature of the classifier it is required to ignore all
58 	 * packets originating from softirq context as accessing `current'
59 	 * would lead to false results.
60 	 *
61 	 * This test assumes that all callers of dev_queue_xmit() explicitly
62 	 * disable bh. Knowing this, it is possible to detect softirq based
63 	 * calls by looking at the number of nested bh disable calls because
64 	 * softirqs always disables bh.
65 	 */
66 	if (in_serving_softirq()) {
67 		struct sock *sk = skb_to_full_sk(skb);
68 
69 		/* If there is an sock_cgroup_classid we'll use that. */
70 		if (!sk || !sk_fullsock(sk))
71 			return 0;
72 
73 		classid = sock_cgroup_classid(&sk->sk_cgrp_data);
74 	}
75 
76 	return classid;
77 }
78 #else /* !CONFIG_CGROUP_NET_CLASSID */
sock_update_classid(struct sock_cgroup_data * skcd)79 static inline void sock_update_classid(struct sock_cgroup_data *skcd)
80 {
81 }
82 
task_get_classid(const struct sk_buff * skb)83 static inline u32 task_get_classid(const struct sk_buff *skb)
84 {
85 	return 0;
86 }
87 #endif /* CONFIG_CGROUP_NET_CLASSID */
88 #endif  /* _NET_CLS_CGROUP_H */
89