net/sched/cls_api.c

   1 /*
   2  * net/sched/cls_api.c  Packet classifier API.
   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:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  * Changes:
  12  *
  13  * Eduardo J. Blanco <ejbs@netlabs.com.uy> :990222: kmod support
  14  *
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/string.h>
  21 #include <linux/errno.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/init.h>
  24 #include <linux/kmod.h>
  25 #include <linux/err.h>
  26 #include <linux/slab.h>
  27 #include <net/net_namespace.h>
  28 #include <net/sock.h>
  29 #include <net/netlink.h>
  30 #include <net/pkt_sched.h>
  31 #include <net/pkt_cls.h>
  32
  33 /* The list of all installed classifier types */
  34 static LIST_HEAD(tcf_proto_base);
  35
  36 /* Protects list of registered TC modules. It is pure SMP lock. */
  37 static DEFINE_RWLOCK(cls_mod_lock);
  38
  39 /* Find classifier type by string name */
  40
  41 static const struct tcf_proto_ops *tcf_proto_lookup_ops(struct nlattr *kind)
  42 {
  43         const struct tcf_proto_ops *t, *res = NULL;
  44
  45         if (kind) {
  46                 read_lock(&cls_mod_lock);
  47                 list_for_each_entry(t, &tcf_proto_base, head) {
  48                         if (nla_strcmp(kind, t->kind) == 0) {
  49                                 if (try_module_get(t->owner))
  50                                         res = t;
  51                                 break;
  52                         }
  53                 }
  54                 read_unlock(&cls_mod_lock);
  55         }
  56         return res;
  57 }
  58
  59 /* Register(unregister) new classifier type */
  60
  61 int register_tcf_proto_ops(struct tcf_proto_ops *ops)
  62 {
  63         struct tcf_proto_ops *t;
  64         int rc = -EEXIST;
  65
  66         write_lock(&cls_mod_lock);
  67         list_for_each_entry(t, &tcf_proto_base, head)
  68                 if (!strcmp(ops->kind, t->kind))
  69                         goto out;
  70
  71         list_add_tail(&ops->head, &tcf_proto_base);
  72         rc = 0;
  73 out:
  74         write_unlock(&cls_mod_lock);
  75         return rc;
  76 }
  77 EXPORT_SYMBOL(register_tcf_proto_ops);
  78
  79 int unregister_tcf_proto_ops(struct tcf_proto_ops *ops)
  80 {
  81         struct tcf_proto_ops *t;
  82         int rc = -ENOENT;
  83
  84         /* Wait for outstanding call_rcu()s, if any, from a
  85          * tcf_proto_ops's destroy() handler.
  86          */
  87         rcu_barrier();
  88
  89         write_lock(&cls_mod_lock);
  90         list_for_each_entry(t, &tcf_proto_base, head) {
  91                 if (t == ops) {
  92                         list_del(&t->head);
  93                         rc = 0;
  94                         break;
  95                 }
  96         }
  97         write_unlock(&cls_mod_lock);
  98         return rc;
  99 }
 100 EXPORT_SYMBOL(unregister_tcf_proto_ops);
 101
 102 static int tfilter_notify(struct net *net, struct sk_buff *oskb,
 103                           struct nlmsghdr *n, struct tcf_proto *tp,
 104                           unsigned long fh, int event);
 105
 106
 107 /* Select new prio value from the range, managed by kernel. */
 108
 109 static inline u32 tcf_auto_prio(struct tcf_proto *tp)
 110 {
 111         u32 first = TC_H_MAKE(0xC0000000U, 0U);
 112
 113         if (tp)
 114                 first = tp->prio - 1;
 115
 116         return first;
 117 }
 118
 119 /* Add/change/delete/get a filter node */
 120
 121 static int tc_ctl_tfilter(struct sk_buff *skb, struct nlmsghdr *n)
 122 {
 123         struct net *net = sock_net(skb->sk);
 124         struct nlattr *tca[TCA_MAX + 1];
 125         struct tcmsg *t;
 126         u32 protocol;
 127         u32 prio;
 128         u32 nprio;
 129         u32 parent;
 130         struct net_device *dev;
 131         struct Qdisc  *q;
 132         struct tcf_proto __rcu **back;
 133         struct tcf_proto __rcu **chain;
 134         struct tcf_proto *tp;
 135         const struct tcf_proto_ops *tp_ops;
 136         const struct Qdisc_class_ops *cops;
 137         unsigned long cl;
 138         unsigned long fh;
 139         int err;
 140         int tp_created = 0;
 141
 142         if ((n->nlmsg_type != RTM_GETTFILTER) &&
 143             !netlink_ns_capable(skb, net->user_ns, CAP_NET_ADMIN))
 144                 return -EPERM;
 145
 146 replay:
 147         err = nlmsg_parse(n, sizeof(*t), tca, TCA_MAX, NULL);
 148         if (err < 0)
 149                 return err;
 150
 151         t = nlmsg_data(n);
 152         protocol = TC_H_MIN(t->tcm_info);
 153         prio = TC_H_MAJ(t->tcm_info);
 154         nprio = prio;
 155         parent = t->tcm_parent;
 156         cl = 0;
 157
 158         if (prio == 0) {
 159                 /* If no priority is given, user wants we allocated it. */
 160                 if (n->nlmsg_type != RTM_NEWTFILTER ||
 161                     !(n->nlmsg_flags & NLM_F_CREATE))
 162                         return -ENOENT;
 163                 prio = TC_H_MAKE(0x80000000U, 0U);
 164         }
 165
 166         /* Find head of filter chain. */
 167
 168         /* Find link */
 169         dev = __dev_get_by_index(net, t->tcm_ifindex);
 170         if (dev == NULL)
 171                 return -ENODEV;
 172
 173         /* Find qdisc */
 174         if (!parent) {
 175                 q = dev->qdisc;
 176                 parent = q->handle;
 177         } else {
 178                 q = qdisc_lookup(dev, TC_H_MAJ(t->tcm_parent));
 179                 if (q == NULL)
 180                         return -EINVAL;
 181         }
 182
 183         /* Is it classful? */
 184         cops = q->ops->cl_ops;
 185         if (!cops)
 186                 return -EINVAL;
 187
 188         if (cops->tcf_chain == NULL)
 189                 return -EOPNOTSUPP;
 190
 191         /* Do we search for filter, attached to class? */
 192         if (TC_H_MIN(parent)) {
 193                 cl = cops->get(q, parent);
 194                 if (cl == 0)
 195                         return -ENOENT;
 196         }
 197
 198         /* And the last stroke */
 199         chain = cops->tcf_chain(q, cl);
 200         err = -EINVAL;
 201         if (chain == NULL)
 202                 goto errout;
 203
 204         /* Check the chain for existence of proto-tcf with this priority */
 205         for (back = chain;
 206              (tp = rtnl_dereference(*back)) != NULL;
 207              back = &tp->next) {
 208                 if (tp->prio >= prio) {
 209                         if (tp->prio == prio) {
 210                                 if (!nprio ||
 211                                     (tp->protocol != protocol && protocol))
 212                                         goto errout;
 213                         } else
 214                                 tp = NULL;
 215                         break;
 216                 }
 217         }
 218
 219         if (tp == NULL) {
 220                 /* Proto-tcf does not exist, create new one */
 221
 222                 if (tca[TCA_KIND] == NULL || !protocol)
 223                         goto errout;
 224
 225                 err = -ENOENT;
 226                 if (n->nlmsg_type != RTM_NEWTFILTER ||
 227                     !(n->nlmsg_flags & NLM_F_CREATE))
 228                         goto errout;
 229
 230
 231                 /* Create new proto tcf */
 232
 233                 err = -ENOBUFS;
 234                 tp = kzalloc(sizeof(*tp), GFP_KERNEL);
 235                 if (tp == NULL)
 236                         goto errout;
 237                 err = -ENOENT;
 238                 tp_ops = tcf_proto_lookup_ops(tca[TCA_KIND]);
 239                 if (tp_ops == NULL) {
 240 #ifdef CONFIG_MODULES
 241                         struct nlattr *kind = tca[TCA_KIND];
 242                         char name[IFNAMSIZ];
 243
 244                         if (kind != NULL &&
 245                             nla_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
 246                                 rtnl_unlock();
 247                                 request_module("cls_%s", name);
 248                                 rtnl_lock();
 249                                 tp_ops = tcf_proto_lookup_ops(kind);
 250                                 /* We dropped the RTNL semaphore in order to
 251                                  * perform the module load.  So, even if we
 252                                  * succeeded in loading the module we have to
 253                                  * replay the request.  We indicate this using
 254                                  * -EAGAIN.
 255                                  */
 256                                 if (tp_ops != NULL) {
 257                                         module_put(tp_ops->owner);
 258                                         err = -EAGAIN;
 259                                 }
 260                         }
 261 #endif
 262                         kfree(tp);
 263                         goto errout;
 264                 }
 265                 tp->ops = tp_ops;
 266                 tp->protocol = protocol;
 267                 tp->prio = nprio ? :
 268                                TC_H_MAJ(tcf_auto_prio(rtnl_dereference(*back)));
 269                 tp->q = q;
 270                 tp->classify = tp_ops->classify;
 271                 tp->classid = parent;
 272
 273                 err = tp_ops->init(tp);
 274                 if (err != 0) {
 275                         module_put(tp_ops->owner);
 276                         kfree(tp);
 277                         goto errout;
 278                 }
 279
 280                 tp_created = 1;
 281
 282         } else if (tca[TCA_KIND] && nla_strcmp(tca[TCA_KIND], tp->ops->kind))
 283                 goto errout;
 284
 285         fh = tp->ops->get(tp, t->tcm_handle);
 286
 287         if (fh == 0) {
 288                 if (n->nlmsg_type == RTM_DELTFILTER && t->tcm_handle == 0) {
 289                         struct tcf_proto *next = rtnl_dereference(tp->next);
 290
 291                         RCU_INIT_POINTER(*back, next);
 292
 293                         tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
 294                         tcf_destroy(tp, true);
 295                         err = 0;
 296                         goto errout;
 297                 }
 298
 299                 err = -ENOENT;
 300                 if (n->nlmsg_type != RTM_NEWTFILTER ||
 301                     !(n->nlmsg_flags & NLM_F_CREATE))
 302                         goto errout;
 303         } else {
 304                 switch (n->nlmsg_type) {
 305                 case RTM_NEWTFILTER:
 306                         err = -EEXIST;
 307                         if (n->nlmsg_flags & NLM_F_EXCL) {
 308                                 if (tp_created)
 309                                         tcf_destroy(tp, true);
 310                                 goto errout;
 311                         }
 312                         break;
 313                 case RTM_DELTFILTER:
 314                         err = tp->ops->delete(tp, fh);
 315                         if (err == 0) {
 316                                 struct tcf_proto *next = rtnl_dereference(tp->next);
 317
 318                                 tfilter_notify(net, skb, n, tp, fh, RTM_DELTFILTER);
 319                                 if (tcf_destroy(tp, false))
 320                                         RCU_INIT_POINTER(*back, next);
 321                         }
 322                         goto errout;
 323                 case RTM_GETTFILTER:
 324                         err = tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
 325                         goto errout;
 326                 default:
 327                         err = -EINVAL;
 328                         goto errout;
 329                 }
 330         }
 331
 332         err = tp->ops->change(net, skb, tp, cl, t->tcm_handle, tca, &fh,
 333                               n->nlmsg_flags & NLM_F_CREATE ? TCA_ACT_NOREPLACE : TCA_ACT_REPLACE);
 334         if (err == 0) {
 335                 if (tp_created) {
 336                         RCU_INIT_POINTER(tp->next, rtnl_dereference(*back));
 337                         rcu_assign_pointer(*back, tp);
 338                 }
 339                 tfilter_notify(net, skb, n, tp, fh, RTM_NEWTFILTER);
 340         } else {
 341                 if (tp_created)
 342                         tcf_destroy(tp, true);
 343         }
 344
 345 errout:
 346         if (cl)
 347                 cops->put(q, cl);
 348         if (err == -EAGAIN)
 349                 /* Replay the request. */
 350                 goto replay;
 351         return err;
 352 }
 353
 354 static int tcf_fill_node(struct net *net, struct sk_buff *skb, struct tcf_proto *tp,
 355                          unsigned long fh, u32 portid, u32 seq, u16 flags, int event)
 356 {
 357         struct tcmsg *tcm;
 358         struct nlmsghdr  *nlh;
 359         unsigned char *b = skb_tail_pointer(skb);
 360
 361         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*tcm), flags);
 362         if (!nlh)
 363                 goto out_nlmsg_trim;
 364         tcm = nlmsg_data(nlh);
 365         tcm->tcm_family = AF_UNSPEC;
 366         tcm->tcm__pad1 = 0;
 367         tcm->tcm__pad2 = 0;
 368         tcm->tcm_ifindex = qdisc_dev(tp->q)->ifindex;
 369         tcm->tcm_parent = tp->classid;
 370         tcm->tcm_info = TC_H_MAKE(tp->prio, tp->protocol);
 371         if (nla_put_string(skb, TCA_KIND, tp->ops->kind))
 372                 goto nla_put_failure;
 373         tcm->tcm_handle = fh;
 374         if (RTM_DELTFILTER != event) {
 375                 tcm->tcm_handle = 0;
 376                 if (tp->ops->dump && tp->ops->dump(net, tp, fh, skb, tcm) < 0)
 377                         goto nla_put_failure;
 378         }
 379         nlh->nlmsg_len = skb_tail_pointer(skb) - b;
 380         return skb->len;
 381
 382 out_nlmsg_trim:
 383 nla_put_failure:
 384         nlmsg_trim(skb, b);
 385         return -1;
 386 }
 387
 388 static int tfilter_notify(struct net *net, struct sk_buff *oskb,
 389                           struct nlmsghdr *n, struct tcf_proto *tp,
 390                           unsigned long fh, int event)
 391 {
 392         struct sk_buff *skb;
 393         u32 portid = oskb ? NETLINK_CB(oskb).portid : 0;
 394
 395         skb = alloc_skb(NLMSG_GOODSIZE, GFP_KERNEL);
 396         if (!skb)
 397                 return -ENOBUFS;
 398
 399         if (tcf_fill_node(net, skb, tp, fh, portid, n->nlmsg_seq, 0, event) <= 0) {
 400                 kfree_skb(skb);
 401                 return -EINVAL;
 402         }
 403
 404         return rtnetlink_send(skb, net, portid, RTNLGRP_TC,
 405                               n->nlmsg_flags & NLM_F_ECHO);
 406 }
 407
 408 struct tcf_dump_args {
 409         struct tcf_walker w;
 410         struct sk_buff *skb;
 411         struct netlink_callback *cb;
 412 };
 413
 414 static int tcf_node_dump(struct tcf_proto *tp, unsigned long n,
 415                          struct tcf_walker *arg)
 416 {
 417         struct tcf_dump_args *a = (void *)arg;
 418         struct net *net = sock_net(a->skb->sk);
 419
 420         return tcf_fill_node(net, a->skb, tp, n, NETLINK_CB(a->cb->skb).portid,
 421                              a->cb->nlh->nlmsg_seq, NLM_F_MULTI, RTM_NEWTFILTER);
 422 }
 423
 424 /* called with RTNL */
 425 static int tc_dump_tfilter(struct sk_buff *skb, struct netlink_callback *cb)
 426 {
 427         struct net *net = sock_net(skb->sk);
 428         int t;
 429         int s_t;
 430         struct net_device *dev;
 431         struct Qdisc *q;
 432         struct tcf_proto *tp, __rcu **chain;
 433         struct tcmsg *tcm = nlmsg_data(cb->nlh);
 434         unsigned long cl = 0;
 435         const struct Qdisc_class_ops *cops;
 436         struct tcf_dump_args arg;
 437
 438         if (nlmsg_len(cb->nlh) < sizeof(*tcm))
 439                 return skb->len;
 440         dev = __dev_get_by_index(net, tcm->tcm_ifindex);
 441         if (!dev)
 442                 return skb->len;
 443
 444         if (!tcm->tcm_parent)
 445                 q = dev->qdisc;
 446         else
 447                 q = qdisc_lookup(dev, TC_H_MAJ(tcm->tcm_parent));
 448         if (!q)
 449                 goto out;
 450         cops = q->ops->cl_ops;
 451         if (!cops)
 452                 goto errout;
 453         if (cops->tcf_chain == NULL)
 454                 goto errout;
 455         if (TC_H_MIN(tcm->tcm_parent)) {
 456                 cl = cops->get(q, tcm->tcm_parent);
 457                 if (cl == 0)
 458                         goto errout;
 459         }
 460         chain = cops->tcf_chain(q, cl);
 461         if (chain == NULL)
 462                 goto errout;
 463
 464         s_t = cb->args[0];
 465
 466         for (tp = rtnl_dereference(*chain), t = 0;
 467              tp; tp = rtnl_dereference(tp->next), t++) {
 468                 if (t < s_t)
 469                         continue;
 470                 if (TC_H_MAJ(tcm->tcm_info) &&
 471                     TC_H_MAJ(tcm->tcm_info) != tp->prio)
 472                         continue;
 473                 if (TC_H_MIN(tcm->tcm_info) &&
 474                     TC_H_MIN(tcm->tcm_info) != tp->protocol)
 475                         continue;
 476                 if (t > s_t)
 477                         memset(&cb->args[1], 0, sizeof(cb->args)-sizeof(cb->args[0]));
 478                 if (cb->args[1] == 0) {
 479                         if (tcf_fill_node(net, skb, tp, 0, NETLINK_CB(cb->skb).portid,
 480                                           cb->nlh->nlmsg_seq, NLM_F_MULTI,
 481                                           RTM_NEWTFILTER) <= 0)
 482                                 break;
 483
 484                         cb->args[1] = 1;
 485                 }
 486                 if (tp->ops->walk == NULL)
 487                         continue;
 488                 arg.w.fn = tcf_node_dump;
 489                 arg.skb = skb;
 490                 arg.cb = cb;
 491                 arg.w.stop = 0;
 492                 arg.w.skip = cb->args[1] - 1;
 493                 arg.w.count = 0;
 494                 tp->ops->walk(tp, &arg.w);
 495                 cb->args[1] = arg.w.count + 1;
 496                 if (arg.w.stop)
 497                         break;
 498         }
 499
 500         cb->args[0] = t;
 501
 502 errout:
 503         if (cl)
 504                 cops->put(q, cl);
 505 out:
 506         return skb->len;
 507 }
 508
 509 void tcf_exts_destroy(struct tcf_exts *exts)
 510 {
 511 #ifdef CONFIG_NET_CLS_ACT
 512         tcf_action_destroy(&exts->actions, TCA_ACT_UNBIND);
 513         INIT_LIST_HEAD(&exts->actions);
 514 #endif
 515 }
 516 EXPORT_SYMBOL(tcf_exts_destroy);
 517
 518 int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb,
 519                   struct nlattr *rate_tlv, struct tcf_exts *exts, bool ovr)
 520 {
 521 #ifdef CONFIG_NET_CLS_ACT
 522         {
 523                 struct tc_action *act;
 524
 525                 INIT_LIST_HEAD(&exts->actions);
 526                 if (exts->police && tb[exts->police]) {
 527                         act = tcf_action_init_1(net, tb[exts->police], rate_tlv,
 528                                                 "police", ovr,
 529                                                 TCA_ACT_BIND);
 530                         if (IS_ERR(act))
 531                                 return PTR_ERR(act);
 532
 533                         act->type = exts->type = TCA_OLD_COMPAT;
 534                         list_add(&act->list, &exts->actions);
 535                 } else if (exts->action && tb[exts->action]) {
 536                         int err;
 537                         err = tcf_action_init(net, tb[exts->action], rate_tlv,
 538                                               NULL, ovr,
 539                                               TCA_ACT_BIND, &exts->actions);
 540                         if (err)
 541                                 return err;
 542                 }
 543         }
 544 #else
 545         if ((exts->action && tb[exts->action]) ||
 546             (exts->police && tb[exts->police]))
 547                 return -EOPNOTSUPP;
 548 #endif
 549
 550         return 0;
 551 }
 552 EXPORT_SYMBOL(tcf_exts_validate);
 553
 554 void tcf_exts_change(struct tcf_proto *tp, struct tcf_exts *dst,
 555                      struct tcf_exts *src)
 556 {
 557 #ifdef CONFIG_NET_CLS_ACT
 558         LIST_HEAD(tmp);
 559         tcf_tree_lock(tp);
 560         list_splice_init(&dst->actions, &tmp);
 561         list_splice(&src->actions, &dst->actions);
 562         dst->type = src->type;
 563         tcf_tree_unlock(tp);
 564         tcf_action_destroy(&tmp, TCA_ACT_UNBIND);
 565 #endif
 566 }
 567 EXPORT_SYMBOL(tcf_exts_change);
 568
 569 #define tcf_exts_first_act(ext)                                 \
 570         list_first_entry_or_null(&(exts)->actions,              \
 571                                  struct tc_action, list)
 572
 573 int tcf_exts_dump(struct sk_buff *skb, struct tcf_exts *exts)
 574 {
 575 #ifdef CONFIG_NET_CLS_ACT
 576         struct nlattr *nest;
 577
 578         if (exts->action && !list_empty(&exts->actions)) {
 579                 /*
 580                  * again for backward compatible mode - we want
 581                  * to work with both old and new modes of entering
 582                  * tc data even if iproute2  was newer - jhs
 583                  */
 584                 if (exts->type != TCA_OLD_COMPAT) {
 585                         nest = nla_nest_start(skb, exts->action);
 586                         if (nest == NULL)
 587                                 goto nla_put_failure;
 588                         if (tcf_action_dump(skb, &exts->actions, 0, 0) < 0)
 589                                 goto nla_put_failure;
 590                         nla_nest_end(skb, nest);
 591                 } else if (exts->police) {
 592                         struct tc_action *act = tcf_exts_first_act(exts);
 593                         nest = nla_nest_start(skb, exts->police);
 594                         if (nest == NULL || !act)
 595                                 goto nla_put_failure;
 596                         if (tcf_action_dump_old(skb, act, 0, 0) < 0)
 597                                 goto nla_put_failure;
 598                         nla_nest_end(skb, nest);
 599                 }
 600         }
 601         return 0;
 602
 603 nla_put_failure:
 604         nla_nest_cancel(skb, nest);
 605         return -1;
 606 #else
 607         return 0;
 608 #endif
 609 }
 610 EXPORT_SYMBOL(tcf_exts_dump);
 611
 612
 613 int tcf_exts_dump_stats(struct sk_buff *skb, struct tcf_exts *exts)
 614 {
 615 #ifdef CONFIG_NET_CLS_ACT
 616         struct tc_action *a = tcf_exts_first_act(exts);
 617         if (a != NULL && tcf_action_copy_stats(skb, a, 1) < 0)
 618                 return -1;
 619 #endif
 620         return 0;
 621 }
 622 EXPORT_SYMBOL(tcf_exts_dump_stats);
 623
 624 static int __init tc_filter_init(void)
 625 {
 626         rtnl_register(PF_UNSPEC, RTM_NEWTFILTER, tc_ctl_tfilter, NULL, NULL);
 627         rtnl_register(PF_UNSPEC, RTM_DELTFILTER, tc_ctl_tfilter, NULL, NULL);
 628         rtnl_register(PF_UNSPEC, RTM_GETTFILTER, tc_ctl_tfilter,
 629                       tc_dump_tfilter, NULL);
 630
 631         return 0;
 632 }
 633
 634 subsys_initcall(tc_filter_init);