net/sched/cls_flow.c

   1 /*
   2  * net/sched/cls_flow.c         Generic flow classifier
   3  *
   4  * Copyright (c) 2007, 2008 Patrick McHardy <kaber@trash.net>
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version 2
   9  * of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/list.h>
  15 #include <linux/jhash.h>
  16 #include <linux/random.h>
  17 #include <linux/pkt_cls.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/in.h>
  20 #include <linux/ip.h>
  21 #include <linux/ipv6.h>
  22 #include <linux/if_vlan.h>
  23
  24 #include <net/pkt_cls.h>
  25 #include <net/ip.h>
  26 #include <net/route.h>
  27 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
  28 #include <net/netfilter/nf_conntrack.h>
  29 #endif
  30
  31 struct flow_head {
  32         struct list_head        filters;
  33 };
  34
  35 struct flow_filter {
  36         struct list_head        list;
  37         struct tcf_exts         exts;
  38         struct tcf_ematch_tree  ematches;
  39         struct timer_list       perturb_timer;
  40         u32                     perturb_period;
  41         u32                     handle;
  42
  43         u32                     nkeys;
  44         u32                     keymask;
  45         u32                     mode;
  46         u32                     mask;
  47         u32                     xor;
  48         u32                     rshift;
  49         u32                     addend;
  50         u32                     divisor;
  51         u32                     baseclass;
  52         u32                     hashrnd;
  53 };
  54
  55 static const struct tcf_ext_map flow_ext_map = {
  56         .action = TCA_FLOW_ACT,
  57         .police = TCA_FLOW_POLICE,
  58 };
  59
  60 static inline u32 addr_fold(void *addr)
  61 {
  62         unsigned long a = (unsigned long)addr;
  63
  64         return (a & 0xFFFFFFFF) ^ (BITS_PER_LONG > 32 ? a >> 32 : 0);
  65 }
  66
  67 static u32 flow_get_src(const struct sk_buff *skb)
  68 {
  69         switch (skb->protocol) {
  70         case __constant_htons(ETH_P_IP):
  71                 return ntohl(ip_hdr(skb)->saddr);
  72         case __constant_htons(ETH_P_IPV6):
  73                 return ntohl(ipv6_hdr(skb)->saddr.s6_addr32[3]);
  74         default:
  75                 return addr_fold(skb->sk);
  76         }
  77 }
  78
  79 static u32 flow_get_dst(const struct sk_buff *skb)
  80 {
  81         switch (skb->protocol) {
  82         case __constant_htons(ETH_P_IP):
  83                 return ntohl(ip_hdr(skb)->daddr);
  84         case __constant_htons(ETH_P_IPV6):
  85                 return ntohl(ipv6_hdr(skb)->daddr.s6_addr32[3]);
  86         default:
  87                 return addr_fold(skb->dst) ^ (__force u16)skb->protocol;
  88         }
  89 }
  90
  91 static u32 flow_get_proto(const struct sk_buff *skb)
  92 {
  93         switch (skb->protocol) {
  94         case __constant_htons(ETH_P_IP):
  95                 return ip_hdr(skb)->protocol;
  96         case __constant_htons(ETH_P_IPV6):
  97                 return ipv6_hdr(skb)->nexthdr;
  98         default:
  99                 return 0;
 100         }
 101 }
 102
 103 static int has_ports(u8 protocol)
 104 {
 105         switch (protocol) {
 106         case IPPROTO_TCP:
 107         case IPPROTO_UDP:
 108         case IPPROTO_UDPLITE:
 109         case IPPROTO_SCTP:
 110         case IPPROTO_DCCP:
 111         case IPPROTO_ESP:
 112                 return 1;
 113         default:
 114                 return 0;
 115         }
 116 }
 117
 118 static u32 flow_get_proto_src(const struct sk_buff *skb)
 119 {
 120         u32 res = 0;
 121
 122         switch (skb->protocol) {
 123         case __constant_htons(ETH_P_IP): {
 124                 struct iphdr *iph = ip_hdr(skb);
 125
 126                 if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
 127                     has_ports(iph->protocol))
 128                         res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4));
 129                 break;
 130         }
 131         case __constant_htons(ETH_P_IPV6): {
 132                 struct ipv6hdr *iph = ipv6_hdr(skb);
 133
 134                 if (has_ports(iph->nexthdr))
 135                         res = ntohs(*(__be16 *)&iph[1]);
 136                 break;
 137         }
 138         default:
 139                 res = addr_fold(skb->sk);
 140         }
 141
 142         return res;
 143 }
 144
 145 static u32 flow_get_proto_dst(const struct sk_buff *skb)
 146 {
 147         u32 res = 0;
 148
 149         switch (skb->protocol) {
 150         case __constant_htons(ETH_P_IP): {
 151                 struct iphdr *iph = ip_hdr(skb);
 152
 153                 if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
 154                     has_ports(iph->protocol))
 155                         res = ntohs(*(__be16 *)((void *)iph + iph->ihl * 4 + 2));
 156                 break;
 157         }
 158         case __constant_htons(ETH_P_IPV6): {
 159                 struct ipv6hdr *iph = ipv6_hdr(skb);
 160
 161                 if (has_ports(iph->nexthdr))
 162                         res = ntohs(*(__be16 *)((void *)&iph[1] + 2));
 163                 break;
 164         }
 165         default:
 166                 res = addr_fold(skb->dst) ^ (__force u16)skb->protocol;
 167         }
 168
 169         return res;
 170 }
 171
 172 static u32 flow_get_iif(const struct sk_buff *skb)
 173 {
 174         return skb->iif;
 175 }
 176
 177 static u32 flow_get_priority(const struct sk_buff *skb)
 178 {
 179         return skb->priority;
 180 }
 181
 182 static u32 flow_get_mark(const struct sk_buff *skb)
 183 {
 184         return skb->mark;
 185 }
 186
 187 static u32 flow_get_nfct(const struct sk_buff *skb)
 188 {
 189 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 190         return addr_fold(skb->nfct);
 191 #else
 192         return 0;
 193 #endif
 194 }
 195
 196 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 197 #define CTTUPLE(skb, member)                                            \
 198 ({                                                                      \
 199         enum ip_conntrack_info ctinfo;                                  \
 200         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);                   \
 201         if (ct == NULL)                                                 \
 202                 goto fallback;                                          \
 203         ct->tuplehash[CTINFO2DIR(ctinfo)].tuple.member;                 \
 204 })
 205 #else
 206 #define CTTUPLE(skb, member)                                            \
 207 ({                                                                      \
 208         goto fallback;                                                  \
 209         0;                                                              \
 210 })
 211 #endif
 212
 213 static u32 flow_get_nfct_src(const struct sk_buff *skb)
 214 {
 215         switch (skb->protocol) {
 216         case __constant_htons(ETH_P_IP):
 217                 return ntohl(CTTUPLE(skb, src.u3.ip));
 218         case __constant_htons(ETH_P_IPV6):
 219                 return ntohl(CTTUPLE(skb, src.u3.ip6[3]));
 220         }
 221 fallback:
 222         return flow_get_src(skb);
 223 }
 224
 225 static u32 flow_get_nfct_dst(const struct sk_buff *skb)
 226 {
 227         switch (skb->protocol) {
 228         case __constant_htons(ETH_P_IP):
 229                 return ntohl(CTTUPLE(skb, dst.u3.ip));
 230         case __constant_htons(ETH_P_IPV6):
 231                 return ntohl(CTTUPLE(skb, dst.u3.ip6[3]));
 232         }
 233 fallback:
 234         return flow_get_dst(skb);
 235 }
 236
 237 static u32 flow_get_nfct_proto_src(const struct sk_buff *skb)
 238 {
 239         return ntohs(CTTUPLE(skb, src.u.all));
 240 fallback:
 241         return flow_get_proto_src(skb);
 242 }
 243
 244 static u32 flow_get_nfct_proto_dst(const struct sk_buff *skb)
 245 {
 246         return ntohs(CTTUPLE(skb, dst.u.all));
 247 fallback:
 248         return flow_get_proto_dst(skb);
 249 }
 250
 251 static u32 flow_get_rtclassid(const struct sk_buff *skb)
 252 {
 253 #ifdef CONFIG_NET_CLS_ROUTE
 254         if (skb->dst)
 255                 return skb->dst->tclassid;
 256 #endif
 257         return 0;
 258 }
 259
 260 static u32 flow_get_skuid(const struct sk_buff *skb)
 261 {
 262         if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
 263                 return skb->sk->sk_socket->file->f_uid;
 264         return 0;
 265 }
 266
 267 static u32 flow_get_skgid(const struct sk_buff *skb)
 268 {
 269         if (skb->sk && skb->sk->sk_socket && skb->sk->sk_socket->file)
 270                 return skb->sk->sk_socket->file->f_gid;
 271         return 0;
 272 }
 273
 274 static u32 flow_get_vlan_tag(const struct sk_buff *skb)
 275 {
 276         u16 uninitialized_var(tag);
 277
 278         if (vlan_get_tag(skb, &tag) < 0)
 279                 return 0;
 280         return tag & VLAN_VID_MASK;
 281 }
 282
 283 static u32 flow_key_get(const struct sk_buff *skb, int key)
 284 {
 285         switch (key) {
 286         case FLOW_KEY_SRC:
 287                 return flow_get_src(skb);
 288         case FLOW_KEY_DST:
 289                 return flow_get_dst(skb);
 290         case FLOW_KEY_PROTO:
 291                 return flow_get_proto(skb);
 292         case FLOW_KEY_PROTO_SRC:
 293                 return flow_get_proto_src(skb);
 294         case FLOW_KEY_PROTO_DST:
 295                 return flow_get_proto_dst(skb);
 296         case FLOW_KEY_IIF:
 297                 return flow_get_iif(skb);
 298         case FLOW_KEY_PRIORITY:
 299                 return flow_get_priority(skb);
 300         case FLOW_KEY_MARK:
 301                 return flow_get_mark(skb);
 302         case FLOW_KEY_NFCT:
 303                 return flow_get_nfct(skb);
 304         case FLOW_KEY_NFCT_SRC:
 305                 return flow_get_nfct_src(skb);
 306         case FLOW_KEY_NFCT_DST:
 307                 return flow_get_nfct_dst(skb);
 308         case FLOW_KEY_NFCT_PROTO_SRC:
 309                 return flow_get_nfct_proto_src(skb);
 310         case FLOW_KEY_NFCT_PROTO_DST:
 311                 return flow_get_nfct_proto_dst(skb);
 312         case FLOW_KEY_RTCLASSID:
 313                 return flow_get_rtclassid(skb);
 314         case FLOW_KEY_SKUID:
 315                 return flow_get_skuid(skb);
 316         case FLOW_KEY_SKGID:
 317                 return flow_get_skgid(skb);
 318         case FLOW_KEY_VLAN_TAG:
 319                 return flow_get_vlan_tag(skb);
 320         default:
 321                 WARN_ON(1);
 322                 return 0;
 323         }
 324 }
 325
 326 static int flow_classify(struct sk_buff *skb, struct tcf_proto *tp,
 327                          struct tcf_result *res)
 328 {
 329         struct flow_head *head = tp->root;
 330         struct flow_filter *f;
 331         u32 keymask;
 332         u32 classid;
 333         unsigned int n, key;
 334         int r;
 335
 336         list_for_each_entry(f, &head->filters, list) {
 337                 u32 keys[f->nkeys];
 338
 339                 if (!tcf_em_tree_match(skb, &f->ematches, NULL))
 340                         continue;
 341
 342                 keymask = f->keymask;
 343
 344                 for (n = 0; n < f->nkeys; n++) {
 345                         key = ffs(keymask) - 1;
 346                         keymask &= ~(1 << key);
 347                         keys[n] = flow_key_get(skb, key);
 348                 }
 349
 350                 if (f->mode == FLOW_MODE_HASH)
 351                         classid = jhash2(keys, f->nkeys, f->hashrnd);
 352                 else {
 353                         classid = keys[0];
 354                         classid = (classid & f->mask) ^ f->xor;
 355                         classid = (classid >> f->rshift) + f->addend;
 356                 }
 357
 358                 if (f->divisor)
 359                         classid %= f->divisor;
 360
 361                 res->class   = 0;
 362                 res->classid = TC_H_MAKE(f->baseclass, f->baseclass + classid);
 363
 364                 r = tcf_exts_exec(skb, &f->exts, res);
 365                 if (r < 0)
 366                         continue;
 367                 return r;
 368         }
 369         return -1;
 370 }
 371
 372 static void flow_perturbation(unsigned long arg)
 373 {
 374         struct flow_filter *f = (struct flow_filter *)arg;
 375
 376         get_random_bytes(&f->hashrnd, 4);
 377         if (f->perturb_period)
 378                 mod_timer(&f->perturb_timer, jiffies + f->perturb_period);
 379 }
 380
 381 static const struct nla_policy flow_policy[TCA_FLOW_MAX + 1] = {
 382         [TCA_FLOW_KEYS]         = { .type = NLA_U32 },
 383         [TCA_FLOW_MODE]         = { .type = NLA_U32 },
 384         [TCA_FLOW_BASECLASS]    = { .type = NLA_U32 },
 385         [TCA_FLOW_RSHIFT]       = { .type = NLA_U32 },
 386         [TCA_FLOW_ADDEND]       = { .type = NLA_U32 },
 387         [TCA_FLOW_MASK]         = { .type = NLA_U32 },
 388         [TCA_FLOW_XOR]          = { .type = NLA_U32 },
 389         [TCA_FLOW_DIVISOR]      = { .type = NLA_U32 },
 390         [TCA_FLOW_ACT]          = { .type = NLA_NESTED },
 391         [TCA_FLOW_POLICE]       = { .type = NLA_NESTED },
 392         [TCA_FLOW_EMATCHES]     = { .type = NLA_NESTED },
 393         [TCA_FLOW_PERTURB]      = { .type = NLA_U32 },
 394 };
 395
 396 static int flow_change(struct tcf_proto *tp, unsigned long base,
 397                        u32 handle, struct nlattr **tca,
 398                        unsigned long *arg)
 399 {
 400         struct flow_head *head = tp->root;
 401         struct flow_filter *f;
 402         struct nlattr *opt = tca[TCA_OPTIONS];
 403         struct nlattr *tb[TCA_FLOW_MAX + 1];
 404         struct tcf_exts e;
 405         struct tcf_ematch_tree t;
 406         unsigned int nkeys = 0;
 407         unsigned int perturb_period = 0;
 408         u32 baseclass = 0;
 409         u32 keymask = 0;
 410         u32 mode;
 411         int err;
 412
 413         if (opt == NULL)
 414                 return -EINVAL;
 415
 416         err = nla_parse_nested(tb, TCA_FLOW_MAX, opt, flow_policy);
 417         if (err < 0)
 418                 return err;
 419
 420         if (tb[TCA_FLOW_BASECLASS]) {
 421                 baseclass = nla_get_u32(tb[TCA_FLOW_BASECLASS]);
 422                 if (TC_H_MIN(baseclass) == 0)
 423                         return -EINVAL;
 424         }
 425
 426         if (tb[TCA_FLOW_KEYS]) {
 427                 keymask = nla_get_u32(tb[TCA_FLOW_KEYS]);
 428
 429                 nkeys = hweight32(keymask);
 430                 if (nkeys == 0)
 431                         return -EINVAL;
 432
 433                 if (fls(keymask) - 1 > FLOW_KEY_MAX)
 434                         return -EOPNOTSUPP;
 435         }
 436
 437         err = tcf_exts_validate(tp, tb, tca[TCA_RATE], &e, &flow_ext_map);
 438         if (err < 0)
 439                 return err;
 440
 441         err = tcf_em_tree_validate(tp, tb[TCA_FLOW_EMATCHES], &t);
 442         if (err < 0)
 443                 goto err1;
 444
 445         f = (struct flow_filter *)*arg;
 446         if (f != NULL) {
 447                 err = -EINVAL;
 448                 if (f->handle != handle && handle)
 449                         goto err2;
 450
 451                 mode = f->mode;
 452                 if (tb[TCA_FLOW_MODE])
 453                         mode = nla_get_u32(tb[TCA_FLOW_MODE]);
 454                 if (mode != FLOW_MODE_HASH && nkeys > 1)
 455                         goto err2;
 456
 457                 if (mode == FLOW_MODE_HASH)
 458                         perturb_period = f->perturb_period;
 459                 if (tb[TCA_FLOW_PERTURB]) {
 460                         if (mode != FLOW_MODE_HASH)
 461                                 goto err2;
 462                         perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
 463                 }
 464         } else {
 465                 err = -EINVAL;
 466                 if (!handle)
 467                         goto err2;
 468                 if (!tb[TCA_FLOW_KEYS])
 469                         goto err2;
 470
 471                 mode = FLOW_MODE_MAP;
 472                 if (tb[TCA_FLOW_MODE])
 473                         mode = nla_get_u32(tb[TCA_FLOW_MODE]);
 474                 if (mode != FLOW_MODE_HASH && nkeys > 1)
 475                         goto err2;
 476
 477                 if (tb[TCA_FLOW_PERTURB]) {
 478                         if (mode != FLOW_MODE_HASH)
 479                                 goto err2;
 480                         perturb_period = nla_get_u32(tb[TCA_FLOW_PERTURB]) * HZ;
 481                 }
 482
 483                 if (TC_H_MAJ(baseclass) == 0)
 484                         baseclass = TC_H_MAKE(tp->q->handle, baseclass);
 485                 if (TC_H_MIN(baseclass) == 0)
 486                         baseclass = TC_H_MAKE(baseclass, 1);
 487
 488                 err = -ENOBUFS;
 489                 f = kzalloc(sizeof(*f), GFP_KERNEL);
 490                 if (f == NULL)
 491                         goto err2;
 492
 493                 f->handle = handle;
 494                 f->mask   = ~0U;
 495
 496                 get_random_bytes(&f->hashrnd, 4);
 497                 f->perturb_timer.function = flow_perturbation;
 498                 f->perturb_timer.data = (unsigned long)f;
 499                 init_timer_deferrable(&f->perturb_timer);
 500         }
 501
 502         tcf_exts_change(tp, &f->exts, &e);
 503         tcf_em_tree_change(tp, &f->ematches, &t);
 504
 505         tcf_tree_lock(tp);
 506
 507         if (tb[TCA_FLOW_KEYS]) {
 508                 f->keymask = keymask;
 509                 f->nkeys   = nkeys;
 510         }
 511
 512         f->mode = mode;
 513
 514         if (tb[TCA_FLOW_MASK])
 515                 f->mask = nla_get_u32(tb[TCA_FLOW_MASK]);
 516         if (tb[TCA_FLOW_XOR])
 517                 f->xor = nla_get_u32(tb[TCA_FLOW_XOR]);
 518         if (tb[TCA_FLOW_RSHIFT])
 519                 f->rshift = nla_get_u32(tb[TCA_FLOW_RSHIFT]);
 520         if (tb[TCA_FLOW_ADDEND])
 521                 f->addend = nla_get_u32(tb[TCA_FLOW_ADDEND]);
 522
 523         if (tb[TCA_FLOW_DIVISOR])
 524                 f->divisor = nla_get_u32(tb[TCA_FLOW_DIVISOR]);
 525         if (baseclass)
 526                 f->baseclass = baseclass;
 527
 528         f->perturb_period = perturb_period;
 529         del_timer(&f->perturb_timer);
 530         if (perturb_period)
 531                 mod_timer(&f->perturb_timer, jiffies + perturb_period);
 532
 533         if (*arg == 0)
 534                 list_add_tail(&f->list, &head->filters);
 535
 536         tcf_tree_unlock(tp);
 537
 538         *arg = (unsigned long)f;
 539         return 0;
 540
 541 err2:
 542         tcf_em_tree_destroy(tp, &t);
 543 err1:
 544         tcf_exts_destroy(tp, &e);
 545         return err;
 546 }
 547
 548 static void flow_destroy_filter(struct tcf_proto *tp, struct flow_filter *f)
 549 {
 550         del_timer_sync(&f->perturb_timer);
 551         tcf_exts_destroy(tp, &f->exts);
 552         tcf_em_tree_destroy(tp, &f->ematches);
 553         kfree(f);
 554 }
 555
 556 static int flow_delete(struct tcf_proto *tp, unsigned long arg)
 557 {
 558         struct flow_filter *f = (struct flow_filter *)arg;
 559
 560         tcf_tree_lock(tp);
 561         list_del(&f->list);
 562         tcf_tree_unlock(tp);
 563         flow_destroy_filter(tp, f);
 564         return 0;
 565 }
 566
 567 static int flow_init(struct tcf_proto *tp)
 568 {
 569         struct flow_head *head;
 570
 571         head = kzalloc(sizeof(*head), GFP_KERNEL);
 572         if (head == NULL)
 573                 return -ENOBUFS;
 574         INIT_LIST_HEAD(&head->filters);
 575         tp->root = head;
 576         return 0;
 577 }
 578
 579 static void flow_destroy(struct tcf_proto *tp)
 580 {
 581         struct flow_head *head = tp->root;
 582         struct flow_filter *f, *next;
 583
 584         list_for_each_entry_safe(f, next, &head->filters, list) {
 585                 list_del(&f->list);
 586                 flow_destroy_filter(tp, f);
 587         }
 588         kfree(head);
 589 }
 590
 591 static unsigned long flow_get(struct tcf_proto *tp, u32 handle)
 592 {
 593         struct flow_head *head = tp->root;
 594         struct flow_filter *f;
 595
 596         list_for_each_entry(f, &head->filters, list)
 597                 if (f->handle == handle)
 598                         return (unsigned long)f;
 599         return 0;
 600 }
 601
 602 static void flow_put(struct tcf_proto *tp, unsigned long f)
 603 {
 604         return;
 605 }
 606
 607 static int flow_dump(struct tcf_proto *tp, unsigned long fh,
 608                      struct sk_buff *skb, struct tcmsg *t)
 609 {
 610         struct flow_filter *f = (struct flow_filter *)fh;
 611         struct nlattr *nest;
 612
 613         if (f == NULL)
 614                 return skb->len;
 615
 616         t->tcm_handle = f->handle;
 617
 618         nest = nla_nest_start(skb, TCA_OPTIONS);
 619         if (nest == NULL)
 620                 goto nla_put_failure;
 621
 622         NLA_PUT_U32(skb, TCA_FLOW_KEYS, f->keymask);
 623         NLA_PUT_U32(skb, TCA_FLOW_MODE, f->mode);
 624
 625         if (f->mask != ~0 || f->xor != 0) {
 626                 NLA_PUT_U32(skb, TCA_FLOW_MASK, f->mask);
 627                 NLA_PUT_U32(skb, TCA_FLOW_XOR, f->xor);
 628         }
 629         if (f->rshift)
 630                 NLA_PUT_U32(skb, TCA_FLOW_RSHIFT, f->rshift);
 631         if (f->addend)
 632                 NLA_PUT_U32(skb, TCA_FLOW_ADDEND, f->addend);
 633
 634         if (f->divisor)
 635                 NLA_PUT_U32(skb, TCA_FLOW_DIVISOR, f->divisor);
 636         if (f->baseclass)
 637                 NLA_PUT_U32(skb, TCA_FLOW_BASECLASS, f->baseclass);
 638
 639         if (f->perturb_period)
 640                 NLA_PUT_U32(skb, TCA_FLOW_PERTURB, f->perturb_period / HZ);
 641
 642         if (tcf_exts_dump(skb, &f->exts, &flow_ext_map) < 0)
 643                 goto nla_put_failure;
 644 #ifdef CONFIG_NET_EMATCH
 645         if (f->ematches.hdr.nmatches &&
 646             tcf_em_tree_dump(skb, &f->ematches, TCA_FLOW_EMATCHES) < 0)
 647                 goto nla_put_failure;
 648 #endif
 649         nla_nest_end(skb, nest);
 650
 651         if (tcf_exts_dump_stats(skb, &f->exts, &flow_ext_map) < 0)
 652                 goto nla_put_failure;
 653
 654         return skb->len;
 655
 656 nla_put_failure:
 657         nlmsg_trim(skb, nest);
 658         return -1;
 659 }
 660
 661 static void flow_walk(struct tcf_proto *tp, struct tcf_walker *arg)
 662 {
 663         struct flow_head *head = tp->root;
 664         struct flow_filter *f;
 665
 666         list_for_each_entry(f, &head->filters, list) {
 667                 if (arg->count < arg->skip)
 668                         goto skip;
 669                 if (arg->fn(tp, (unsigned long)f, arg) < 0) {
 670                         arg->stop = 1;
 671                         break;
 672                 }
 673 skip:
 674                 arg->count++;
 675         }
 676 }
 677
 678 static struct tcf_proto_ops cls_flow_ops __read_mostly = {
 679         .kind           = "flow",
 680         .classify       = flow_classify,
 681         .init           = flow_init,
 682         .destroy        = flow_destroy,
 683         .change         = flow_change,
 684         .delete         = flow_delete,
 685         .get            = flow_get,
 686         .put            = flow_put,
 687         .dump           = flow_dump,
 688         .walk           = flow_walk,
 689         .owner          = THIS_MODULE,
 690 };
 691
 692 static int __init cls_flow_init(void)
 693 {
 694         return register_tcf_proto_ops(&cls_flow_ops);
 695 }
 696
 697 static void __exit cls_flow_exit(void)
 698 {
 699         unregister_tcf_proto_ops(&cls_flow_ops);
 700 }
 701
 702 module_init(cls_flow_init);
 703 module_exit(cls_flow_exit);
 704
 705 MODULE_LICENSE("GPL");
 706 MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
 707 MODULE_DESCRIPTION("TC flow classifier");