net/sched/cls_cgroup.c

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