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/skbuff.h> 15 #include <linux/rcupdate.h> 16 #include <net/rtnetlink.h> 17 #include <net/pkt_cls.h> 18 #include <net/sock.h> 19 #include <net/cls_cgroup.h> 20 21 struct cls_cgroup_head { 22 u32 handle; 23 struct tcf_exts exts; 24 struct tcf_ematch_tree ematches; 25 struct tcf_proto *tp; 26 struct rcu_head rcu; 27 }; 28 29 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp, 30 struct tcf_result *res) 31 { 32 struct cls_cgroup_head *head = rcu_dereference_bh(tp->root); 33 u32 classid; 34 35 classid = task_cls_state(current)->classid; 36 37 /* 38 * Due to the nature of the classifier it is required to ignore all 39 * packets originating from softirq context as accessing `current' 40 * would lead to false results. 41 * 42 * This test assumes that all callers of dev_queue_xmit() explicitely 43 * disable bh. Knowing this, it is possible to detect softirq based 44 * calls by looking at the number of nested bh disable calls because 45 * softirqs always disables bh. 46 */ 47 if (in_serving_softirq()) { 48 /* If there is an sk_classid we'll use that. */ 49 if (!skb->sk) 50 return -1; 51 classid = skb->sk->sk_classid; 52 } 53 54 if (!classid) 55 return -1; 56 57 if (!tcf_em_tree_match(skb, &head->ematches, NULL)) 58 return -1; 59 60 res->classid = classid; 61 res->class = 0; 62 return tcf_exts_exec(skb, &head->exts, res); 63 } 64 65 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle) 66 { 67 return 0UL; 68 } 69 70 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f) 71 { 72 } 73 74 static int cls_cgroup_init(struct tcf_proto *tp) 75 { 76 return 0; 77 } 78 79 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = { 80 [TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED }, 81 }; 82 83 static void cls_cgroup_destroy_rcu(struct rcu_head *root) 84 { 85 struct cls_cgroup_head *head = container_of(root, 86 struct cls_cgroup_head, 87 rcu); 88 89 tcf_exts_destroy(&head->exts); 90 tcf_em_tree_destroy(&head->ematches); 91 kfree(head); 92 } 93 94 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb, 95 struct tcf_proto *tp, unsigned long base, 96 u32 handle, struct nlattr **tca, 97 unsigned long *arg, bool ovr) 98 { 99 struct nlattr *tb[TCA_CGROUP_MAX + 1]; 100 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 101 struct cls_cgroup_head *new; 102 struct tcf_ematch_tree t; 103 struct tcf_exts e; 104 int err; 105 106 if (!tca[TCA_OPTIONS]) 107 return -EINVAL; 108 109 if (!head && !handle) 110 return -EINVAL; 111 112 if (head && handle != head->handle) 113 return -ENOENT; 114 115 new = kzalloc(sizeof(*head), GFP_KERNEL); 116 if (!new) 117 return -ENOBUFS; 118 119 tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE); 120 if (head) 121 new->handle = head->handle; 122 else 123 new->handle = handle; 124 125 new->tp = tp; 126 err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS], 127 cgroup_policy); 128 if (err < 0) 129 goto errout; 130 131 tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE); 132 err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr); 133 if (err < 0) 134 goto errout; 135 136 err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t); 137 if (err < 0) { 138 tcf_exts_destroy(&e); 139 goto errout; 140 } 141 142 tcf_exts_change(tp, &new->exts, &e); 143 tcf_em_tree_change(tp, &new->ematches, &t); 144 145 rcu_assign_pointer(tp->root, new); 146 if (head) 147 call_rcu(&head->rcu, cls_cgroup_destroy_rcu); 148 return 0; 149 errout: 150 kfree(new); 151 return err; 152 } 153 154 static void cls_cgroup_destroy(struct tcf_proto *tp) 155 { 156 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 157 158 if (head) { 159 RCU_INIT_POINTER(tp->root, NULL); 160 call_rcu(&head->rcu, cls_cgroup_destroy_rcu); 161 } 162 } 163 164 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg) 165 { 166 return -EOPNOTSUPP; 167 } 168 169 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg) 170 { 171 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 172 173 if (arg->count < arg->skip) 174 goto skip; 175 176 if (arg->fn(tp, (unsigned long) head, arg) < 0) { 177 arg->stop = 1; 178 return; 179 } 180 skip: 181 arg->count++; 182 } 183 184 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 185 struct sk_buff *skb, struct tcmsg *t) 186 { 187 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 188 unsigned char *b = skb_tail_pointer(skb); 189 struct nlattr *nest; 190 191 t->tcm_handle = head->handle; 192 193 nest = nla_nest_start(skb, TCA_OPTIONS); 194 if (nest == NULL) 195 goto nla_put_failure; 196 197 if (tcf_exts_dump(skb, &head->exts) < 0 || 198 tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0) 199 goto nla_put_failure; 200 201 nla_nest_end(skb, nest); 202 203 if (tcf_exts_dump_stats(skb, &head->exts) < 0) 204 goto nla_put_failure; 205 206 return skb->len; 207 208 nla_put_failure: 209 nlmsg_trim(skb, b); 210 return -1; 211 } 212 213 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = { 214 .kind = "cgroup", 215 .init = cls_cgroup_init, 216 .change = cls_cgroup_change, 217 .classify = cls_cgroup_classify, 218 .destroy = cls_cgroup_destroy, 219 .get = cls_cgroup_get, 220 .put = cls_cgroup_put, 221 .delete = cls_cgroup_delete, 222 .walk = cls_cgroup_walk, 223 .dump = cls_cgroup_dump, 224 .owner = THIS_MODULE, 225 }; 226 227 static int __init init_cgroup_cls(void) 228 { 229 return register_tcf_proto_ops(&cls_cgroup_ops); 230 } 231 232 static void __exit exit_cgroup_cls(void) 233 { 234 unregister_tcf_proto_ops(&cls_cgroup_ops); 235 } 236 237 module_init(init_cgroup_cls); 238 module_exit(exit_cgroup_cls); 239 MODULE_LICENSE("GPL"); 240