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