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 int cls_cgroup_init(struct tcf_proto *tp) 71 { 72 return 0; 73 } 74 75 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = { 76 [TCA_CGROUP_EMATCHES] = { .type = NLA_NESTED }, 77 }; 78 79 static void cls_cgroup_destroy_rcu(struct rcu_head *root) 80 { 81 struct cls_cgroup_head *head = container_of(root, 82 struct cls_cgroup_head, 83 rcu); 84 85 tcf_exts_destroy(&head->exts); 86 tcf_em_tree_destroy(&head->ematches); 87 kfree(head); 88 } 89 90 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb, 91 struct tcf_proto *tp, unsigned long base, 92 u32 handle, struct nlattr **tca, 93 unsigned long *arg, bool ovr) 94 { 95 struct nlattr *tb[TCA_CGROUP_MAX + 1]; 96 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 97 struct cls_cgroup_head *new; 98 struct tcf_ematch_tree t; 99 struct tcf_exts e; 100 int err; 101 102 if (!tca[TCA_OPTIONS]) 103 return -EINVAL; 104 105 if (!head && !handle) 106 return -EINVAL; 107 108 if (head && handle != head->handle) 109 return -ENOENT; 110 111 new = kzalloc(sizeof(*head), GFP_KERNEL); 112 if (!new) 113 return -ENOBUFS; 114 115 tcf_exts_init(&new->exts, TCA_CGROUP_ACT, TCA_CGROUP_POLICE); 116 new->handle = handle; 117 new->tp = tp; 118 err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS], 119 cgroup_policy); 120 if (err < 0) 121 goto errout; 122 123 tcf_exts_init(&e, TCA_CGROUP_ACT, TCA_CGROUP_POLICE); 124 err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e, ovr); 125 if (err < 0) 126 goto errout; 127 128 err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t); 129 if (err < 0) { 130 tcf_exts_destroy(&e); 131 goto errout; 132 } 133 134 tcf_exts_change(tp, &new->exts, &e); 135 tcf_em_tree_change(tp, &new->ematches, &t); 136 137 rcu_assign_pointer(tp->root, new); 138 if (head) 139 call_rcu(&head->rcu, cls_cgroup_destroy_rcu); 140 return 0; 141 errout: 142 kfree(new); 143 return err; 144 } 145 146 static void cls_cgroup_destroy(struct tcf_proto *tp) 147 { 148 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 149 150 if (head) { 151 RCU_INIT_POINTER(tp->root, NULL); 152 call_rcu(&head->rcu, cls_cgroup_destroy_rcu); 153 } 154 } 155 156 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg) 157 { 158 return -EOPNOTSUPP; 159 } 160 161 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg) 162 { 163 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 164 165 if (arg->count < arg->skip) 166 goto skip; 167 168 if (arg->fn(tp, (unsigned long) head, arg) < 0) { 169 arg->stop = 1; 170 return; 171 } 172 skip: 173 arg->count++; 174 } 175 176 static int cls_cgroup_dump(struct net *net, struct tcf_proto *tp, unsigned long fh, 177 struct sk_buff *skb, struct tcmsg *t) 178 { 179 struct cls_cgroup_head *head = rtnl_dereference(tp->root); 180 struct nlattr *nest; 181 182 t->tcm_handle = head->handle; 183 184 nest = nla_nest_start(skb, TCA_OPTIONS); 185 if (nest == NULL) 186 goto nla_put_failure; 187 188 if (tcf_exts_dump(skb, &head->exts) < 0 || 189 tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0) 190 goto nla_put_failure; 191 192 nla_nest_end(skb, nest); 193 194 if (tcf_exts_dump_stats(skb, &head->exts) < 0) 195 goto nla_put_failure; 196 197 return skb->len; 198 199 nla_put_failure: 200 nla_nest_cancel(skb, nest); 201 return -1; 202 } 203 204 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = { 205 .kind = "cgroup", 206 .init = cls_cgroup_init, 207 .change = cls_cgroup_change, 208 .classify = cls_cgroup_classify, 209 .destroy = cls_cgroup_destroy, 210 .get = cls_cgroup_get, 211 .delete = cls_cgroup_delete, 212 .walk = cls_cgroup_walk, 213 .dump = cls_cgroup_dump, 214 .owner = THIS_MODULE, 215 }; 216 217 static int __init init_cgroup_cls(void) 218 { 219 return register_tcf_proto_ops(&cls_cgroup_ops); 220 } 221 222 static void __exit exit_cgroup_cls(void) 223 { 224 unregister_tcf_proto_ops(&cls_cgroup_ops); 225 } 226 227 module_init(init_cgroup_cls); 228 module_exit(exit_cgroup_cls); 229 MODULE_LICENSE("GPL"); 230