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 <linux/fdtable.h>
  21 #include <net/rtnetlink.h>
  22 #include <net/pkt_cls.h>
  23 #include <net/sock.h>
  24 #include <net/cls_cgroup.h>
  25
  26 static inline struct cgroup_cls_state *cgrp_cls_state(struct cgroup *cgrp)
  27 {
  28         return container_of(cgroup_subsys_state(cgrp, net_cls_subsys_id),
  29                             struct cgroup_cls_state, css);
  30 }
  31
  32 static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p)
  33 {
  34         return container_of(task_subsys_state(p, net_cls_subsys_id),
  35                             struct cgroup_cls_state, css);
  36 }
  37
  38 static struct cgroup_subsys_state *cgrp_css_alloc(struct cgroup *cgrp)
  39 {
  40         struct cgroup_cls_state *cs;
  41
  42         cs = kzalloc(sizeof(*cs), GFP_KERNEL);
  43         if (!cs)
  44                 return ERR_PTR(-ENOMEM);
  45         return &cs->css;
  46 }
  47
  48 static int cgrp_css_online(struct cgroup *cgrp)
  49 {
  50         if (cgrp->parent)
  51                 cgrp_cls_state(cgrp)->classid =
  52                         cgrp_cls_state(cgrp->parent)->classid;
  53         return 0;
  54 }
  55
  56 static void cgrp_css_free(struct cgroup *cgrp)
  57 {
  58         kfree(cgrp_cls_state(cgrp));
  59 }
  60
  61 static int update_classid(const void *v, struct file *file, unsigned n)
  62 {
  63         int err;
  64         struct socket *sock = sock_from_file(file, &err);
  65         if (sock)
  66                 sock->sk->sk_classid = (u32)(unsigned long)v;
  67         return 0;
  68 }
  69
  70 static void cgrp_attach(struct cgroup *cgrp, struct cgroup_taskset *tset)
  71 {
  72         struct task_struct *p;
  73         void *v;
  74
  75         cgroup_taskset_for_each(p, cgrp, tset) {
  76                 task_lock(p);
  77                 v = (void *)(unsigned long)task_cls_classid(p);
  78                 iterate_fd(p->files, 0, update_classid, v);
  79                 task_unlock(p);
  80         }
  81 }
  82
  83 static u64 read_classid(struct cgroup *cgrp, struct cftype *cft)
  84 {
  85         return cgrp_cls_state(cgrp)->classid;
  86 }
  87
  88 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
  89 {
  90         cgrp_cls_state(cgrp)->classid = (u32) value;
  91         return 0;
  92 }
  93
  94 static struct cftype ss_files[] = {
  95         {
  96                 .name = "classid",
  97                 .read_u64 = read_classid,
  98                 .write_u64 = write_classid,
  99         },
 100         { }     /* terminate */
 101 };
 102
 103 struct cgroup_subsys net_cls_subsys = {
 104         .name           = "net_cls",
 105         .css_alloc      = cgrp_css_alloc,
 106         .css_online     = cgrp_css_online,
 107         .css_free       = cgrp_css_free,
 108         .attach         = cgrp_attach,
 109         .subsys_id      = net_cls_subsys_id,
 110         .base_cftypes   = ss_files,
 111         .module         = THIS_MODULE,
 112 };
 113
 114 struct cls_cgroup_head {
 115         u32                     handle;
 116         struct tcf_exts         exts;
 117         struct tcf_ematch_tree  ematches;
 118 };
 119
 120 static int cls_cgroup_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 121                                struct tcf_result *res)
 122 {
 123         struct cls_cgroup_head *head = tp->root;
 124         u32 classid;
 125
 126         rcu_read_lock();
 127         classid = task_cls_state(current)->classid;
 128         rcu_read_unlock();
 129
 130         /*
 131          * Due to the nature of the classifier it is required to ignore all
 132          * packets originating from softirq context as accessing `current'
 133          * would lead to false results.
 134          *
 135          * This test assumes that all callers of dev_queue_xmit() explicitely
 136          * disable bh. Knowing this, it is possible to detect softirq based
 137          * calls by looking at the number of nested bh disable calls because
 138          * softirqs always disables bh.
 139          */
 140         if (in_serving_softirq()) {
 141                 /* If there is an sk_classid we'll use that. */
 142                 if (!skb->sk)
 143                         return -1;
 144                 classid = skb->sk->sk_classid;
 145         }
 146
 147         if (!classid)
 148                 return -1;
 149
 150         if (!tcf_em_tree_match(skb, &head->ematches, NULL))
 151                 return -1;
 152
 153         res->classid = classid;
 154         res->class = 0;
 155         return tcf_exts_exec(skb, &head->exts, res);
 156 }
 157
 158 static unsigned long cls_cgroup_get(struct tcf_proto *tp, u32 handle)
 159 {
 160         return 0UL;
 161 }
 162
 163 static void cls_cgroup_put(struct tcf_proto *tp, unsigned long f)
 164 {
 165 }
 166
 167 static int cls_cgroup_init(struct tcf_proto *tp)
 168 {
 169         return 0;
 170 }
 171
 172 static const struct tcf_ext_map cgroup_ext_map = {
 173         .action = TCA_CGROUP_ACT,
 174         .police = TCA_CGROUP_POLICE,
 175 };
 176
 177 static const struct nla_policy cgroup_policy[TCA_CGROUP_MAX + 1] = {
 178         [TCA_CGROUP_EMATCHES]   = { .type = NLA_NESTED },
 179 };
 180
 181 static int cls_cgroup_change(struct net *net, struct sk_buff *in_skb,
 182                              struct tcf_proto *tp, unsigned long base,
 183                              u32 handle, struct nlattr **tca,
 184                              unsigned long *arg)
 185 {
 186         struct nlattr *tb[TCA_CGROUP_MAX + 1];
 187         struct cls_cgroup_head *head = tp->root;
 188         struct tcf_ematch_tree t;
 189         struct tcf_exts e;
 190         int err;
 191
 192         if (!tca[TCA_OPTIONS])
 193                 return -EINVAL;
 194
 195         if (head == NULL) {
 196                 if (!handle)
 197                         return -EINVAL;
 198
 199                 head = kzalloc(sizeof(*head), GFP_KERNEL);
 200                 if (head == NULL)
 201                         return -ENOBUFS;
 202
 203                 head->handle = handle;
 204
 205                 tcf_tree_lock(tp);
 206                 tp->root = head;
 207                 tcf_tree_unlock(tp);
 208         }
 209
 210         if (handle != head->handle)
 211                 return -ENOENT;
 212
 213         err = nla_parse_nested(tb, TCA_CGROUP_MAX, tca[TCA_OPTIONS],
 214                                cgroup_policy);
 215         if (err < 0)
 216                 return err;
 217
 218         err = tcf_exts_validate(net, tp, tb, tca[TCA_RATE], &e,
 219                                 &cgroup_ext_map);
 220         if (err < 0)
 221                 return err;
 222
 223         err = tcf_em_tree_validate(tp, tb[TCA_CGROUP_EMATCHES], &t);
 224         if (err < 0)
 225                 return err;
 226
 227         tcf_exts_change(tp, &head->exts, &e);
 228         tcf_em_tree_change(tp, &head->ematches, &t);
 229
 230         return 0;
 231 }
 232
 233 static void cls_cgroup_destroy(struct tcf_proto *tp)
 234 {
 235         struct cls_cgroup_head *head = tp->root;
 236
 237         if (head) {
 238                 tcf_exts_destroy(tp, &head->exts);
 239                 tcf_em_tree_destroy(tp, &head->ematches);
 240                 kfree(head);
 241         }
 242 }
 243
 244 static int cls_cgroup_delete(struct tcf_proto *tp, unsigned long arg)
 245 {
 246         return -EOPNOTSUPP;
 247 }
 248
 249 static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 250 {
 251         struct cls_cgroup_head *head = tp->root;
 252
 253         if (arg->count < arg->skip)
 254                 goto skip;
 255
 256         if (arg->fn(tp, (unsigned long) head, arg) < 0) {
 257                 arg->stop = 1;
 258                 return;
 259         }
 260 skip:
 261         arg->count++;
 262 }
 263
 264 static int cls_cgroup_dump(struct tcf_proto *tp, unsigned long fh,
 265                            struct sk_buff *skb, struct tcmsg *t)
 266 {
 267         struct cls_cgroup_head *head = tp->root;
 268         unsigned char *b = skb_tail_pointer(skb);
 269         struct nlattr *nest;
 270
 271         t->tcm_handle = head->handle;
 272
 273         nest = nla_nest_start(skb, TCA_OPTIONS);
 274         if (nest == NULL)
 275                 goto nla_put_failure;
 276
 277         if (tcf_exts_dump(skb, &head->exts, &cgroup_ext_map) < 0 ||
 278             tcf_em_tree_dump(skb, &head->ematches, TCA_CGROUP_EMATCHES) < 0)
 279                 goto nla_put_failure;
 280
 281         nla_nest_end(skb, nest);
 282
 283         if (tcf_exts_dump_stats(skb, &head->exts, &cgroup_ext_map) < 0)
 284                 goto nla_put_failure;
 285
 286         return skb->len;
 287
 288 nla_put_failure:
 289         nlmsg_trim(skb, b);
 290         return -1;
 291 }
 292
 293 static struct tcf_proto_ops cls_cgroup_ops __read_mostly = {
 294         .kind           =       "cgroup",
 295         .init           =       cls_cgroup_init,
 296         .change         =       cls_cgroup_change,
 297         .classify       =       cls_cgroup_classify,
 298         .destroy        =       cls_cgroup_destroy,
 299         .get            =       cls_cgroup_get,
 300         .put            =       cls_cgroup_put,
 301         .delete         =       cls_cgroup_delete,
 302         .walk           =       cls_cgroup_walk,
 303         .dump           =       cls_cgroup_dump,
 304         .owner          =       THIS_MODULE,
 305 };
 306
 307 static int __init init_cgroup_cls(void)
 308 {
 309         int ret;
 310
 311         ret = cgroup_load_subsys(&net_cls_subsys);
 312         if (ret)
 313                 goto out;
 314
 315         ret = register_tcf_proto_ops(&cls_cgroup_ops);
 316         if (ret)
 317                 cgroup_unload_subsys(&net_cls_subsys);
 318
 319 out:
 320         return ret;
 321 }
 322
 323 static void __exit exit_cgroup_cls(void)
 324 {
 325         unregister_tcf_proto_ops(&cls_cgroup_ops);
 326
 327         cgroup_unload_subsys(&net_cls_subsys);
 328 }
 329
 330 module_init(init_cgroup_cls);
 331 module_exit(exit_cgroup_cls);
 332 MODULE_LICENSE("GPL");