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