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