cls_cgroup: Fix oops when user send improperly 'tc filter add' request
[linux-2.6.git] / net / sched / cls_cgroup.c
1 /*
2  * net/sched/cls_cgroup.c       Control Group Classifier
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/module.h>
13 #include <linux/types.h>
14 #include <linux/string.h>
15 #include <linux/errno.h>
16 #include <linux/skbuff.h>
17 #include <linux/cgroup.h>
18 #include <net/rtnetlink.h>
19 #include <net/pkt_cls.h>
20
21 struct cgroup_cls_state
22 {
23         struct cgroup_subsys_state css;
24         u32 classid;
25 };
26
27 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
28 {
29         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
30                             struct cgroup_cls_state, css);
31 }
32
33 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
34 {
35         return container_of(task_subsys_state(p, net_cls_subsys_id),
36                             struct cgroup_cls_state, css);
37 }
38
39 static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss,
40                                                  struct cgroup *cgrp)
41 {
42         struct cgroup_cls_state *cs;
43
44         if (!(cs = kzalloc(sizeof(*cs), GFP_KERNEL)))
45                 return ERR_PTR(-ENOMEM);
46
47         if (cgrp->parent)
48                 cs->classid = cgrp_cls_state(cgrp->parent)->classid;
49
50         return &cs->css;
51 }
52
53 static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
54 {
55         kfree(cgrp_cls_state(cgrp));
56 }
57
58 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
59 {
60         return cgrp_cls_state(cgrp)->classid;
61 }
62
63 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
64 {
65         if (!cgroup_lock_live_group(cgrp))
66                 return -ENODEV;
67
68         cgrp_cls_state(cgrp)->classid = (u32) value;
69
70         cgroup_unlock();
71
72         return 0;
73 }
74
75 static struct cftype ss_files[] = {
76         {
77                 .name = "classid",
78                 .read_u64 = read_classid,
79                 .write_u64 = write_classid,
80         },
81 };
82
83 static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
84 {
85         return cgroup_add_files(cgrp, ss, ss_files, ARRAY_SIZE(ss_files));
86 }
87
88 struct cgroup_subsys net_cls_subsys = {
89         .name           = "net_cls",
90         .create         = cgrp_create,
91         .destroy        = cgrp_destroy,
92         .populate       = cgrp_populate,
93         .subsys_id      = net_cls_subsys_id,
94 };
95
96 struct cls_cgroup_head
97 {
98         u32                     handle;
99         struct tcf_exts         exts;
100         struct tcf_ematch_tree  ematches;
101 };
102
103 static int cls_cgroup_classify(struct sk_buff *skb, struct tcf_proto *tp,
104                                struct tcf_result *res)
105 {
106         struct cls_cgroup_head *head = tp->root;
107         u32 classid;
108
109         /*
110          * Due to the nature of the classifier it is required to ignore all
111          * packets originating from softirq context as accessing `current'
112          * would lead to false results.
113          *
114          * This test assumes that all callers of dev_queue_xmit() explicitely
115          * disable bh. Knowing this, it is possible to detect softirq based
116          * calls by looking at the number of nested bh disable calls because
117          * softirqs always disables bh.
118          */
119         if (softirq_count() != SOFTIRQ_OFFSET)
120                 return -1;
121
122         rcu_read_lock();
123         classid = task_cls_state(current)->classid;
124         rcu_read_unlock();
125
126         if (!classid)
127                 return -1;
128
129         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
130                 return -1;
131
132         res->classid = classid;
133         res->class = 0;
134         return tcf_exts_exec(skb, &head->exts, res);
135 }
136
137 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
138 {
139         return 0UL;
140 }
141
142 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
143 {
144 }
145
146 static int cls_cgroup_init(struct tcf_proto *tp)
147 {
148         return 0;
149 }
150
151 static const struct tcf_ext_map cgroup_ext_map = {
152         .action = TCA_CGROUP_ACT,
153         .police = TCA_CGROUP_POLICE,
154 };
155
156 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
157         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
158 };
159
160 static int cls_cgroup_change(struct tcf_proto *tp, unsigned long base,
161                              u32 handle, struct nlattr **tca,
162                              unsigned long *arg)
163 {
164         struct nlattr *tb[TCA_CGROUP_MAX+1];
165         struct cls_cgroup_head *head = tp->root;
166         struct tcf_ematch_tree t;
167         struct tcf_exts e;
168         int err;
169
170         if (!tca[TCA_OPTIONS])
171                 return -EINVAL;
172
173         if (head == NULL) {
174                 if (!handle)
175                         return -EINVAL;
176
177                 head = kzalloc(sizeof(*head), GFP_KERNEL);
178                 if (head == NULL)
179                         return -ENOBUFS;
180
181                 head->handle = handle;
182
183                 tcf_tree_lock(tp);
184                 tp->root = head;
185                 tcf_tree_unlock(tp);
186         }
187
188         if (handle != head->handle)
189                 return -ENOENT;
190
191         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
192                                cgroup_policy);
193         if (err < 0)
194                 return err;
195
196         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &cgroup_ext_map);
197         if (err < 0)
198                 return err;
199
200         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
201         if (err < 0)
202                 return err;
203
204         tcf_exts_change(tp, &head->exts, &e);
205         tcf_em_tree_change(tp, &head->ematches, &t);
206
207         return 0;
208 }
209
210 static void cls_cgroup_destroy(struct tcf_proto *tp)
211 {
212         struct cls_cgroup_head *head = tp->root;
213
214         if (head) {
215                 tcf_exts_destroy(tp, &head->exts);
216                 tcf_em_tree_destroy(tp, &head->ematches);
217                 kfree(head);
218         }
219 }
220
221 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
222 {
223         return -EOPNOTSUPP;
224 }
225
226 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
227 {
228         struct cls_cgroup_head *head = tp->root;
229
230         if (arg->count < arg->skip)
231                 goto skip;
232
233         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
234                 arg->stop = 1;
235                 return;
236         }
237 skip:
238         arg->count++;
239 }
240
241 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
242                            struct sk_buff *skb, struct tcmsg *t)
243 {
244         struct cls_cgroup_head *head = tp->root;
245         unsigned char *b = skb_tail_pointer(skb);
246         struct nlattr *nest;
247
248         t->tcm_handle = head->handle;
249
250         nest = nla_nest_start(skb, TCA_OPTIONS);
251         if (nest == NULL)
252                 goto nla_put_failure;
253
254         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
255             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
256                 goto nla_put_failure;
257
258         nla_nest_end(skb, nest);
259
260         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
261                 goto nla_put_failure;
262
263         return skb->len;
264
265 nla_put_failure:
266         nlmsg_trim(skb, b);
267         return -1;
268 }
269
270 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
271         .kind           =       "cgroup",
272         .init           =       cls_cgroup_init,
273         .change         =       cls_cgroup_change,
274         .classify       =       cls_cgroup_classify,
275         .destroy        =       cls_cgroup_destroy,
276         .get            =       cls_cgroup_get,
277         .put            =       cls_cgroup_put,
278         .delete         =       cls_cgroup_delete,
279         .walk           =       cls_cgroup_walk,
280         .dump           =       cls_cgroup_dump,
281         .owner          =       THIS_MODULE,
282 };
283
284 static int __init init_cgroup_cls(void)
285 {
286         return register_tcf_proto_ops(&cls_cgroup_ops);
287 }
288
289 static void __exit exit_cgroup_cls(void)
290 {
291         unregister_tcf_proto_ops(&cls_cgroup_ops);
292 }
293
294 module_init(init_cgroup_cls);
295 module_exit(exit_cgroup_cls);
296 MODULE_LICENSE("GPL");