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