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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/slab.h> |
14 | #include <linux/types.h> |
15 | #include <linux/string.h> |
16 | #include <linux/errno.h> |
17 | #include <linux/skbuff.h> |
18 | #include <linux/cgroup.h> |
19 | #include <linux/rcupdate.h> |
20 | #include <linux/fdtable.h> |
21 | #include <net/rtnetlink.h> |
22 | #include <net/pkt_cls.h> |
23 | #include <net/sock.h> |
24 | #include <net/cls_cgroup.h> |
25 | |
26 | static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp) |
27 | { |
28 | return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id), |
29 | struct cgroup_cls_state, css); |
30 | } |
31 | |
32 | static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p) |
33 | { |
34 | return container_of(task_subsys_state(p, net_cls_subsys_id), |
35 | struct cgroup_cls_state, css); |
36 | } |
37 | |
38 | static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp) |
39 | { |
40 | struct cgroup_cls_state *cs; |
41 | |
42 | cs = kzalloc(sizeof(*cs), GFP_KERNEL); |
43 | if (!cs) |
44 | return ERR_PTR(-ENOMEM); |
45 | return &cs->css; |
46 | } |
47 | |
48 | static int cgrp_css_online(struct cgroup *cgrp) |
49 | { |
50 | if (cgrp->parent) |
51 | cgrp_cls_state(cgrp)->classid = |
52 | cgrp_cls_state(cgrp->parent)->classid; |
53 | return 0; |
54 | } |
55 | |
56 | static void cgrp_css_free(struct cgroup *cgrp) |
57 | { |
58 | kfree(cgrp_cls_state(cgrp)); |
59 | } |
60 | |
61 | static int update_classid(const void *v, struct file *file, unsigned n) |
62 | { |
63 | int err; |
64 | struct socket *sock = sock_from_file(file, &err); |
65 | if (sock) |
66 | sock->sk->sk_classid = (u32)(unsigned long)v; |
67 | return 0; |
68 | } |
69 | |
70 | static void cgrp_attach(struct cgroup *cgrp, struct cgroup_taskset *tset) |
71 | { |
72 | struct task_struct *p; |
73 | void *v; |
74 | |
75 | cgroup_taskset_for_each(p, cgrp, tset) { |
76 | task_lock(p); |
77 | v = (void *)(unsigned long)task_cls_classid(p); |
78 | iterate_fd(p->files, 0, update_classid, v); |
79 | task_unlock(p); |
80 | } |
81 | } |
82 | |
83 | static u64 read_classid(struct cgroup *cgrp, struct cftype *cft) |
84 | { |
85 | return cgrp_cls_state(cgrp)->classid; |
86 | } |
87 | |
88 | static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value) |
89 | { |
90 | cgrp_cls_state(cgrp)->classid = (u32) value; |
91 | return 0; |
92 | } |
93 | |
94 | static struct cftype ss_files[] = { |
95 | { |
96 | .name = "classid", |
97 | .read_u64 = read_classid, |
98 | .write_u64 = write_classid, |
99 | }, |
100 | { } /* terminate */ |
101 | }; |
102 | |
103 | struct cgroup_subsys net_cls_subsys = { |
104 | .name = "net_cls", |
105 | .css_alloc = cgrp_css_alloc, |
106 | .css_online = cgrp_css_online, |
107 | .css_free = cgrp_css_free, |
108 | .attach = cgrp_attach, |
109 | .subsys_id = net_cls_subsys_id, |
110 | .base_cftypes = ss_files, |
111 | .module = THIS_MODULE, |
112 | }; |
113 | |
114 | struct cls_cgroup_head { |
115 | u32 handle; |
116 | struct tcf_exts exts; |
117 | struct tcf_ematch_tree ematches; |
118 | }; |
119 | |
120 | static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp, |
121 | struct tcf_result *res) |
122 | { |
123 | struct cls_cgroup_head *head = tp->root; |
124 | u32 classid; |
125 | |
126 | rcu_read_lock(); |
127 | classid = task_cls_state(current)->classid; |
128 | rcu_read_unlock(); |
129 | |
130 | /* |
131 | * Due to the nature of the classifier it is required to ignore all |
132 | * packets originating from softirq context as accessing `current' |
133 | * would lead to false results. |
134 | * |
135 | * This test assumes that all callers of dev_queue_xmit() explicitely |
136 | * disable bh. Knowing this, it is possible to detect softirq based |
137 | * calls by looking at the number of nested bh disable calls because |
138 | * softirqs always disables bh. |
139 | */ |
140 | if (in_serving_softirq()) { |
141 | /* If there is an sk_classid we'll use that. */ |
142 | if (!skb->sk) |
143 | return -1; |
144 | classid = skb->sk->sk_classid; |
145 | } |
146 | |
147 | if (!classid) |
148 | return -1; |
149 | |
150 | if (!tcf_em_tree_match(skb, &head->ematches, NULL)) |
151 | return -1; |
152 | |
153 | res->classid = classid; |
154 | res->class = 0; |
155 | return tcf_exts_exec(skb, &head->exts, res); |
156 | } |
157 | |
158 | static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle) |
159 | { |
160 | return 0UL; |
161 | } |
162 | |
163 | static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f) |
164 | { |
165 | } |
166 | |
167 | static int cls_cgroup_init(struct tcf_proto *tp) |
168 | { |
169 | return 0; |
170 | } |
171 | |
172 | static const struct tcf_ext_map cgroup_ext_map = { |
173 | .action = TCA_CGROUP_ACT, |
174 | .police = TCA_CGROUP_POLICE, |
175 | }; |
176 | |
177 | static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = { |
178 | [TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED }, |
179 | }; |
180 | |
181 | static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb, |
182 | struct tcf_proto *tp, unsigned long base, |
183 | u32 handle, struct nlattr **tca, |
184 | unsigned long *arg) |
185 | { |
186 | struct nlattr *tb[TCA_CGROUP_MAX + 1]; |
187 | struct cls_cgroup_head *head = tp->root; |
188 | struct tcf_ematch_tree t; |
189 | struct tcf_exts e; |
190 | int err; |
191 | |
192 | if (!tca[TCA_OPTIONS]) |
193 | return -EINVAL; |
194 | |
195 | if (head == NULL) { |
196 | if (!handle) |
197 | return -EINVAL; |
198 | |
199 | head = kzalloc(sizeof(*head), GFP_KERNEL); |
200 | if (head == NULL) |
201 | return -ENOBUFS; |
202 | |
203 | head->handle = handle; |
204 | |
205 | tcf_tree_lock(tp); |
206 | tp->root = head; |
207 | tcf_tree_unlock(tp); |
208 | } |
209 | |
210 | if (handle != head->handle) |
211 | return -ENOENT; |
212 | |
213 | err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS], |
214 | cgroup_policy); |
215 | if (err < 0) |
216 | return err; |
217 | |
218 | err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, |
219 | &cgroup_ext_map); |
220 | if (err < 0) |
221 | return err; |
222 | |
223 | err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t); |
224 | if (err < 0) |
225 | return err; |
226 | |
227 | tcf_exts_change(tp, &head->exts, &e); |
228 | tcf_em_tree_change(tp, &head->ematches, &t); |
229 | |
230 | return 0; |
231 | } |
232 | |
233 | static void cls_cgroup_destroy(struct tcf_proto *tp) |
234 | { |
235 | struct cls_cgroup_head *head = tp->root; |
236 | |
237 | if (head) { |
238 | tcf_exts_destroy(tp, &head->exts); |
239 | tcf_em_tree_destroy(tp, &head->ematches); |
240 | kfree(head); |
241 | } |
242 | } |
243 | |
244 | static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg) |
245 | { |
246 | return -EOPNOTSUPP; |
247 | } |
248 | |
249 | static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg) |
250 | { |
251 | struct cls_cgroup_head *head = tp->root; |
252 | |
253 | if (arg->count < arg->skip) |
254 | goto skip; |
255 | |
256 | if (arg->fn(tp, (unsigned long) head, arg) < 0) { |
257 | arg->stop = 1; |
258 | return; |
259 | } |
260 | skip: |
261 | arg->count++; |
262 | } |
263 | |
264 | static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh, |
265 | struct sk_buff *skb, struct tcmsg *t) |
266 | { |
267 | struct cls_cgroup_head *head = tp->root; |
268 | unsigned char *b = skb_tail_pointer(skb); |
269 | struct nlattr *nest; |
270 | |
271 | t->tcm_handle = head->handle; |
272 | |
273 | nest = nla_nest_start(skb, TCA_OPTIONS); |
274 | if (nest == NULL) |
275 | goto nla_put_failure; |
276 | |
277 | if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 || |
278 | tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0) |
279 | goto nla_put_failure; |
280 | |
281 | nla_nest_end(skb, nest); |
282 | |
283 | if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0) |
284 | goto nla_put_failure; |
285 | |
286 | return skb->len; |
287 | |
288 | nla_put_failure: |
289 | nlmsg_trim(skb, b); |
290 | return -1; |
291 | } |
292 | |
293 | static struct tcf_proto_ops cls_cgroup_ops __read_mostly = { |
294 | .kind = "cgroup", |
295 | .init = cls_cgroup_init, |
296 | .change = cls_cgroup_change, |
297 | .classify = cls_cgroup_classify, |
298 | .destroy = cls_cgroup_destroy, |
299 | .get = cls_cgroup_get, |
300 | .put = cls_cgroup_put, |
301 | .delete = cls_cgroup_delete, |
302 | .walk = cls_cgroup_walk, |
303 | .dump = cls_cgroup_dump, |
304 | .owner = THIS_MODULE, |
305 | }; |
306 | |
307 | static int __init init_cgroup_cls(void) |
308 | { |
309 | int ret; |
310 | |
311 | ret = cgroup_load_subsys(&net_cls_subsys); |
312 | if (ret) |
313 | goto out; |
314 | |
315 | ret = register_tcf_proto_ops(&cls_cgroup_ops); |
316 | if (ret) |
317 | cgroup_unload_subsys(&net_cls_subsys); |
318 | |
319 | out: |
320 | return ret; |
321 | } |
322 | |
323 | static void __exit exit_cgroup_cls(void) |
324 | { |
325 | unregister_tcf_proto_ops(&cls_cgroup_ops); |
326 | |
327 | cgroup_unload_subsys(&net_cls_subsys); |
328 | } |
329 | |
330 | module_init(init_cgroup_cls); |
331 | module_exit(exit_cgroup_cls); |
332 | MODULE_LICENSE("GPL"); |
333 |
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