1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/kernel.h> 3 #include <linux/skbuff.h> 4 #include <linux/export.h> 5 #include <linux/ip.h> 6 #include <linux/ipv6.h> 7 #include <linux/if_vlan.h> 8 #include <net/dsa.h> 9 #include <net/dst_metadata.h> 10 #include <net/ip.h> 11 #include <net/ipv6.h> 12 #include <net/gre.h> 13 #include <net/pptp.h> 14 #include <net/tipc.h> 15 #include <linux/igmp.h> 16 #include <linux/icmp.h> 17 #include <linux/sctp.h> 18 #include <linux/dccp.h> 19 #include <linux/if_tunnel.h> 20 #include <linux/if_pppox.h> 21 #include <linux/ppp_defs.h> 22 #include <linux/stddef.h> 23 #include <linux/if_ether.h> 24 #include <linux/mpls.h> 25 #include <linux/tcp.h> 26 #include <linux/ptp_classify.h> 27 #include <net/flow_dissector.h> 28 #include <scsi/fc/fc_fcoe.h> 29 #include <uapi/linux/batadv_packet.h> 30 #include <linux/bpf.h> 31 #if IS_ENABLED(CONFIG_NF_CONNTRACK) 32 #include <net/netfilter/nf_conntrack_core.h> 33 #include <net/netfilter/nf_conntrack_labels.h> 34 #endif 35 #include <linux/bpf-netns.h> 36 37 static void dissector_set_key(struct flow_dissector *flow_dissector, 38 enum flow_dissector_key_id key_id) 39 { 40 flow_dissector->used_keys |= (1 << key_id); 41 } 42 43 void skb_flow_dissector_init(struct flow_dissector *flow_dissector, 44 const struct flow_dissector_key *key, 45 unsigned int key_count) 46 { 47 unsigned int i; 48 49 memset(flow_dissector, 0, sizeof(*flow_dissector)); 50 51 for (i = 0; i < key_count; i++, key++) { 52 /* User should make sure that every key target offset is within 53 * boundaries of unsigned short. 54 */ 55 BUG_ON(key->offset > USHRT_MAX); 56 BUG_ON(dissector_uses_key(flow_dissector, 57 key->key_id)); 58 59 dissector_set_key(flow_dissector, key->key_id); 60 flow_dissector->offset[key->key_id] = key->offset; 61 } 62 63 /* Ensure that the dissector always includes control and basic key. 64 * That way we are able to avoid handling lack of these in fast path. 65 */ 66 BUG_ON(!dissector_uses_key(flow_dissector, 67 FLOW_DISSECTOR_KEY_CONTROL)); 68 BUG_ON(!dissector_uses_key(flow_dissector, 69 FLOW_DISSECTOR_KEY_BASIC)); 70 } 71 EXPORT_SYMBOL(skb_flow_dissector_init); 72 73 #ifdef CONFIG_BPF_SYSCALL 74 int flow_dissector_bpf_prog_attach_check(struct net *net, 75 struct bpf_prog *prog) 76 { 77 enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; 78 79 if (net == &init_net) { 80 /* BPF flow dissector in the root namespace overrides 81 * any per-net-namespace one. When attaching to root, 82 * make sure we don't have any BPF program attached 83 * to the non-root namespaces. 84 */ 85 struct net *ns; 86 87 for_each_net(ns) { 88 if (ns == &init_net) 89 continue; 90 if (rcu_access_pointer(ns->bpf.run_array[type])) 91 return -EEXIST; 92 } 93 } else { 94 /* Make sure root flow dissector is not attached 95 * when attaching to the non-root namespace. 96 */ 97 if (rcu_access_pointer(init_net.bpf.run_array[type])) 98 return -EEXIST; 99 } 100 101 return 0; 102 } 103 #endif /* CONFIG_BPF_SYSCALL */ 104 105 /** 106 * __skb_flow_get_ports - extract the upper layer ports and return them 107 * @skb: sk_buff to extract the ports from 108 * @thoff: transport header offset 109 * @ip_proto: protocol for which to get port offset 110 * @data: raw buffer pointer to the packet, if NULL use skb->data 111 * @hlen: packet header length, if @data is NULL use skb_headlen(skb) 112 * 113 * The function will try to retrieve the ports at offset thoff + poff where poff 114 * is the protocol port offset returned from proto_ports_offset 115 */ 116 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto, 117 const void *data, int hlen) 118 { 119 int poff = proto_ports_offset(ip_proto); 120 121 if (!data) { 122 data = skb->data; 123 hlen = skb_headlen(skb); 124 } 125 126 if (poff >= 0) { 127 __be32 *ports, _ports; 128 129 ports = __skb_header_pointer(skb, thoff + poff, 130 sizeof(_ports), data, hlen, &_ports); 131 if (ports) 132 return *ports; 133 } 134 135 return 0; 136 } 137 EXPORT_SYMBOL(__skb_flow_get_ports); 138 139 static bool icmp_has_id(u8 type) 140 { 141 switch (type) { 142 case ICMP_ECHO: 143 case ICMP_ECHOREPLY: 144 case ICMP_TIMESTAMP: 145 case ICMP_TIMESTAMPREPLY: 146 case ICMPV6_ECHO_REQUEST: 147 case ICMPV6_ECHO_REPLY: 148 return true; 149 } 150 151 return false; 152 } 153 154 /** 155 * skb_flow_get_icmp_tci - extract ICMP(6) Type, Code and Identifier fields 156 * @skb: sk_buff to extract from 157 * @key_icmp: struct flow_dissector_key_icmp to fill 158 * @data: raw buffer pointer to the packet 159 * @thoff: offset to extract at 160 * @hlen: packet header length 161 */ 162 void skb_flow_get_icmp_tci(const struct sk_buff *skb, 163 struct flow_dissector_key_icmp *key_icmp, 164 const void *data, int thoff, int hlen) 165 { 166 struct icmphdr *ih, _ih; 167 168 ih = __skb_header_pointer(skb, thoff, sizeof(_ih), data, hlen, &_ih); 169 if (!ih) 170 return; 171 172 key_icmp->type = ih->type; 173 key_icmp->code = ih->code; 174 175 /* As we use 0 to signal that the Id field is not present, 176 * avoid confusion with packets without such field 177 */ 178 if (icmp_has_id(ih->type)) 179 key_icmp->id = ih->un.echo.id ? ntohs(ih->un.echo.id) : 1; 180 else 181 key_icmp->id = 0; 182 } 183 EXPORT_SYMBOL(skb_flow_get_icmp_tci); 184 185 /* If FLOW_DISSECTOR_KEY_ICMP is set, dissect an ICMP packet 186 * using skb_flow_get_icmp_tci(). 187 */ 188 static void __skb_flow_dissect_icmp(const struct sk_buff *skb, 189 struct flow_dissector *flow_dissector, 190 void *target_container, const void *data, 191 int thoff, int hlen) 192 { 193 struct flow_dissector_key_icmp *key_icmp; 194 195 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ICMP)) 196 return; 197 198 key_icmp = skb_flow_dissector_target(flow_dissector, 199 FLOW_DISSECTOR_KEY_ICMP, 200 target_container); 201 202 skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen); 203 } 204 205 void skb_flow_dissect_meta(const struct sk_buff *skb, 206 struct flow_dissector *flow_dissector, 207 void *target_container) 208 { 209 struct flow_dissector_key_meta *meta; 210 211 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_META)) 212 return; 213 214 meta = skb_flow_dissector_target(flow_dissector, 215 FLOW_DISSECTOR_KEY_META, 216 target_container); 217 meta->ingress_ifindex = skb->skb_iif; 218 } 219 EXPORT_SYMBOL(skb_flow_dissect_meta); 220 221 static void 222 skb_flow_dissect_set_enc_addr_type(enum flow_dissector_key_id type, 223 struct flow_dissector *flow_dissector, 224 void *target_container) 225 { 226 struct flow_dissector_key_control *ctrl; 227 228 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_CONTROL)) 229 return; 230 231 ctrl = skb_flow_dissector_target(flow_dissector, 232 FLOW_DISSECTOR_KEY_ENC_CONTROL, 233 target_container); 234 ctrl->addr_type = type; 235 } 236 237 void 238 skb_flow_dissect_ct(const struct sk_buff *skb, 239 struct flow_dissector *flow_dissector, 240 void *target_container, u16 *ctinfo_map, 241 size_t mapsize, bool post_ct) 242 { 243 #if IS_ENABLED(CONFIG_NF_CONNTRACK) 244 struct flow_dissector_key_ct *key; 245 enum ip_conntrack_info ctinfo; 246 struct nf_conn_labels *cl; 247 struct nf_conn *ct; 248 249 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_CT)) 250 return; 251 252 ct = nf_ct_get(skb, &ctinfo); 253 if (!ct && !post_ct) 254 return; 255 256 key = skb_flow_dissector_target(flow_dissector, 257 FLOW_DISSECTOR_KEY_CT, 258 target_container); 259 260 if (!ct) { 261 key->ct_state = TCA_FLOWER_KEY_CT_FLAGS_TRACKED | 262 TCA_FLOWER_KEY_CT_FLAGS_INVALID; 263 return; 264 } 265 266 if (ctinfo < mapsize) 267 key->ct_state = ctinfo_map[ctinfo]; 268 #if IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) 269 key->ct_zone = ct->zone.id; 270 #endif 271 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) 272 key->ct_mark = ct->mark; 273 #endif 274 275 cl = nf_ct_labels_find(ct); 276 if (cl) 277 memcpy(key->ct_labels, cl->bits, sizeof(key->ct_labels)); 278 #endif /* CONFIG_NF_CONNTRACK */ 279 } 280 EXPORT_SYMBOL(skb_flow_dissect_ct); 281 282 void 283 skb_flow_dissect_tunnel_info(const struct sk_buff *skb, 284 struct flow_dissector *flow_dissector, 285 void *target_container) 286 { 287 struct ip_tunnel_info *info; 288 struct ip_tunnel_key *key; 289 290 /* A quick check to see if there might be something to do. */ 291 if (!dissector_uses_key(flow_dissector, 292 FLOW_DISSECTOR_KEY_ENC_KEYID) && 293 !dissector_uses_key(flow_dissector, 294 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS) && 295 !dissector_uses_key(flow_dissector, 296 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS) && 297 !dissector_uses_key(flow_dissector, 298 FLOW_DISSECTOR_KEY_ENC_CONTROL) && 299 !dissector_uses_key(flow_dissector, 300 FLOW_DISSECTOR_KEY_ENC_PORTS) && 301 !dissector_uses_key(flow_dissector, 302 FLOW_DISSECTOR_KEY_ENC_IP) && 303 !dissector_uses_key(flow_dissector, 304 FLOW_DISSECTOR_KEY_ENC_OPTS)) 305 return; 306 307 info = skb_tunnel_info(skb); 308 if (!info) 309 return; 310 311 key = &info->key; 312 313 switch (ip_tunnel_info_af(info)) { 314 case AF_INET: 315 skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV4_ADDRS, 316 flow_dissector, 317 target_container); 318 if (dissector_uses_key(flow_dissector, 319 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS)) { 320 struct flow_dissector_key_ipv4_addrs *ipv4; 321 322 ipv4 = skb_flow_dissector_target(flow_dissector, 323 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS, 324 target_container); 325 ipv4->src = key->u.ipv4.src; 326 ipv4->dst = key->u.ipv4.dst; 327 } 328 break; 329 case AF_INET6: 330 skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV6_ADDRS, 331 flow_dissector, 332 target_container); 333 if (dissector_uses_key(flow_dissector, 334 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS)) { 335 struct flow_dissector_key_ipv6_addrs *ipv6; 336 337 ipv6 = skb_flow_dissector_target(flow_dissector, 338 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS, 339 target_container); 340 ipv6->src = key->u.ipv6.src; 341 ipv6->dst = key->u.ipv6.dst; 342 } 343 break; 344 } 345 346 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_KEYID)) { 347 struct flow_dissector_key_keyid *keyid; 348 349 keyid = skb_flow_dissector_target(flow_dissector, 350 FLOW_DISSECTOR_KEY_ENC_KEYID, 351 target_container); 352 keyid->keyid = tunnel_id_to_key32(key->tun_id); 353 } 354 355 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_PORTS)) { 356 struct flow_dissector_key_ports *tp; 357 358 tp = skb_flow_dissector_target(flow_dissector, 359 FLOW_DISSECTOR_KEY_ENC_PORTS, 360 target_container); 361 tp->src = key->tp_src; 362 tp->dst = key->tp_dst; 363 } 364 365 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_IP)) { 366 struct flow_dissector_key_ip *ip; 367 368 ip = skb_flow_dissector_target(flow_dissector, 369 FLOW_DISSECTOR_KEY_ENC_IP, 370 target_container); 371 ip->tos = key->tos; 372 ip->ttl = key->ttl; 373 } 374 375 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_OPTS)) { 376 struct flow_dissector_key_enc_opts *enc_opt; 377 378 enc_opt = skb_flow_dissector_target(flow_dissector, 379 FLOW_DISSECTOR_KEY_ENC_OPTS, 380 target_container); 381 382 if (info->options_len) { 383 enc_opt->len = info->options_len; 384 ip_tunnel_info_opts_get(enc_opt->data, info); 385 enc_opt->dst_opt_type = info->key.tun_flags & 386 TUNNEL_OPTIONS_PRESENT; 387 } 388 } 389 } 390 EXPORT_SYMBOL(skb_flow_dissect_tunnel_info); 391 392 void skb_flow_dissect_hash(const struct sk_buff *skb, 393 struct flow_dissector *flow_dissector, 394 void *target_container) 395 { 396 struct flow_dissector_key_hash *key; 397 398 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_HASH)) 399 return; 400 401 key = skb_flow_dissector_target(flow_dissector, 402 FLOW_DISSECTOR_KEY_HASH, 403 target_container); 404 405 key->hash = skb_get_hash_raw(skb); 406 } 407 EXPORT_SYMBOL(skb_flow_dissect_hash); 408 409 static enum flow_dissect_ret 410 __skb_flow_dissect_mpls(const struct sk_buff *skb, 411 struct flow_dissector *flow_dissector, 412 void *target_container, const void *data, int nhoff, 413 int hlen, int lse_index, bool *entropy_label) 414 { 415 struct mpls_label *hdr, _hdr; 416 u32 entry, label, bos; 417 418 if (!dissector_uses_key(flow_dissector, 419 FLOW_DISSECTOR_KEY_MPLS_ENTROPY) && 420 !dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS)) 421 return FLOW_DISSECT_RET_OUT_GOOD; 422 423 if (lse_index >= FLOW_DIS_MPLS_MAX) 424 return FLOW_DISSECT_RET_OUT_GOOD; 425 426 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, 427 hlen, &_hdr); 428 if (!hdr) 429 return FLOW_DISSECT_RET_OUT_BAD; 430 431 entry = ntohl(hdr->entry); 432 label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT; 433 bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT; 434 435 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS)) { 436 struct flow_dissector_key_mpls *key_mpls; 437 struct flow_dissector_mpls_lse *lse; 438 439 key_mpls = skb_flow_dissector_target(flow_dissector, 440 FLOW_DISSECTOR_KEY_MPLS, 441 target_container); 442 lse = &key_mpls->ls[lse_index]; 443 444 lse->mpls_ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT; 445 lse->mpls_bos = bos; 446 lse->mpls_tc = (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT; 447 lse->mpls_label = label; 448 dissector_set_mpls_lse(key_mpls, lse_index); 449 } 450 451 if (*entropy_label && 452 dissector_uses_key(flow_dissector, 453 FLOW_DISSECTOR_KEY_MPLS_ENTROPY)) { 454 struct flow_dissector_key_keyid *key_keyid; 455 456 key_keyid = skb_flow_dissector_target(flow_dissector, 457 FLOW_DISSECTOR_KEY_MPLS_ENTROPY, 458 target_container); 459 key_keyid->keyid = cpu_to_be32(label); 460 } 461 462 *entropy_label = label == MPLS_LABEL_ENTROPY; 463 464 return bos ? FLOW_DISSECT_RET_OUT_GOOD : FLOW_DISSECT_RET_PROTO_AGAIN; 465 } 466 467 static enum flow_dissect_ret 468 __skb_flow_dissect_arp(const struct sk_buff *skb, 469 struct flow_dissector *flow_dissector, 470 void *target_container, const void *data, 471 int nhoff, int hlen) 472 { 473 struct flow_dissector_key_arp *key_arp; 474 struct { 475 unsigned char ar_sha[ETH_ALEN]; 476 unsigned char ar_sip[4]; 477 unsigned char ar_tha[ETH_ALEN]; 478 unsigned char ar_tip[4]; 479 } *arp_eth, _arp_eth; 480 const struct arphdr *arp; 481 struct arphdr _arp; 482 483 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ARP)) 484 return FLOW_DISSECT_RET_OUT_GOOD; 485 486 arp = __skb_header_pointer(skb, nhoff, sizeof(_arp), data, 487 hlen, &_arp); 488 if (!arp) 489 return FLOW_DISSECT_RET_OUT_BAD; 490 491 if (arp->ar_hrd != htons(ARPHRD_ETHER) || 492 arp->ar_pro != htons(ETH_P_IP) || 493 arp->ar_hln != ETH_ALEN || 494 arp->ar_pln != 4 || 495 (arp->ar_op != htons(ARPOP_REPLY) && 496 arp->ar_op != htons(ARPOP_REQUEST))) 497 return FLOW_DISSECT_RET_OUT_BAD; 498 499 arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp), 500 sizeof(_arp_eth), data, 501 hlen, &_arp_eth); 502 if (!arp_eth) 503 return FLOW_DISSECT_RET_OUT_BAD; 504 505 key_arp = skb_flow_dissector_target(flow_dissector, 506 FLOW_DISSECTOR_KEY_ARP, 507 target_container); 508 509 memcpy(&key_arp->sip, arp_eth->ar_sip, sizeof(key_arp->sip)); 510 memcpy(&key_arp->tip, arp_eth->ar_tip, sizeof(key_arp->tip)); 511 512 /* Only store the lower byte of the opcode; 513 * this covers ARPOP_REPLY and ARPOP_REQUEST. 514 */ 515 key_arp->op = ntohs(arp->ar_op) & 0xff; 516 517 ether_addr_copy(key_arp->sha, arp_eth->ar_sha); 518 ether_addr_copy(key_arp->tha, arp_eth->ar_tha); 519 520 return FLOW_DISSECT_RET_OUT_GOOD; 521 } 522 523 static enum flow_dissect_ret 524 __skb_flow_dissect_gre(const struct sk_buff *skb, 525 struct flow_dissector_key_control *key_control, 526 struct flow_dissector *flow_dissector, 527 void *target_container, const void *data, 528 __be16 *p_proto, int *p_nhoff, int *p_hlen, 529 unsigned int flags) 530 { 531 struct flow_dissector_key_keyid *key_keyid; 532 struct gre_base_hdr *hdr, _hdr; 533 int offset = 0; 534 u16 gre_ver; 535 536 hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), 537 data, *p_hlen, &_hdr); 538 if (!hdr) 539 return FLOW_DISSECT_RET_OUT_BAD; 540 541 /* Only look inside GRE without routing */ 542 if (hdr->flags & GRE_ROUTING) 543 return FLOW_DISSECT_RET_OUT_GOOD; 544 545 /* Only look inside GRE for version 0 and 1 */ 546 gre_ver = ntohs(hdr->flags & GRE_VERSION); 547 if (gre_ver > 1) 548 return FLOW_DISSECT_RET_OUT_GOOD; 549 550 *p_proto = hdr->protocol; 551 if (gre_ver) { 552 /* Version1 must be PPTP, and check the flags */ 553 if (!(*p_proto == GRE_PROTO_PPP && (hdr->flags & GRE_KEY))) 554 return FLOW_DISSECT_RET_OUT_GOOD; 555 } 556 557 offset += sizeof(struct gre_base_hdr); 558 559 if (hdr->flags & GRE_CSUM) 560 offset += sizeof_field(struct gre_full_hdr, csum) + 561 sizeof_field(struct gre_full_hdr, reserved1); 562 563 if (hdr->flags & GRE_KEY) { 564 const __be32 *keyid; 565 __be32 _keyid; 566 567 keyid = __skb_header_pointer(skb, *p_nhoff + offset, 568 sizeof(_keyid), 569 data, *p_hlen, &_keyid); 570 if (!keyid) 571 return FLOW_DISSECT_RET_OUT_BAD; 572 573 if (dissector_uses_key(flow_dissector, 574 FLOW_DISSECTOR_KEY_GRE_KEYID)) { 575 key_keyid = skb_flow_dissector_target(flow_dissector, 576 FLOW_DISSECTOR_KEY_GRE_KEYID, 577 target_container); 578 if (gre_ver == 0) 579 key_keyid->keyid = *keyid; 580 else 581 key_keyid->keyid = *keyid & GRE_PPTP_KEY_MASK; 582 } 583 offset += sizeof_field(struct gre_full_hdr, key); 584 } 585 586 if (hdr->flags & GRE_SEQ) 587 offset += sizeof_field(struct pptp_gre_header, seq); 588 589 if (gre_ver == 0) { 590 if (*p_proto == htons(ETH_P_TEB)) { 591 const struct ethhdr *eth; 592 struct ethhdr _eth; 593 594 eth = __skb_header_pointer(skb, *p_nhoff + offset, 595 sizeof(_eth), 596 data, *p_hlen, &_eth); 597 if (!eth) 598 return FLOW_DISSECT_RET_OUT_BAD; 599 *p_proto = eth->h_proto; 600 offset += sizeof(*eth); 601 602 /* Cap headers that we access via pointers at the 603 * end of the Ethernet header as our maximum alignment 604 * at that point is only 2 bytes. 605 */ 606 if (NET_IP_ALIGN) 607 *p_hlen = *p_nhoff + offset; 608 } 609 } else { /* version 1, must be PPTP */ 610 u8 _ppp_hdr[PPP_HDRLEN]; 611 u8 *ppp_hdr; 612 613 if (hdr->flags & GRE_ACK) 614 offset += sizeof_field(struct pptp_gre_header, ack); 615 616 ppp_hdr = __skb_header_pointer(skb, *p_nhoff + offset, 617 sizeof(_ppp_hdr), 618 data, *p_hlen, _ppp_hdr); 619 if (!ppp_hdr) 620 return FLOW_DISSECT_RET_OUT_BAD; 621 622 switch (PPP_PROTOCOL(ppp_hdr)) { 623 case PPP_IP: 624 *p_proto = htons(ETH_P_IP); 625 break; 626 case PPP_IPV6: 627 *p_proto = htons(ETH_P_IPV6); 628 break; 629 default: 630 /* Could probably catch some more like MPLS */ 631 break; 632 } 633 634 offset += PPP_HDRLEN; 635 } 636 637 *p_nhoff += offset; 638 key_control->flags |= FLOW_DIS_ENCAPSULATION; 639 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) 640 return FLOW_DISSECT_RET_OUT_GOOD; 641 642 return FLOW_DISSECT_RET_PROTO_AGAIN; 643 } 644 645 /** 646 * __skb_flow_dissect_batadv() - dissect batman-adv header 647 * @skb: sk_buff to with the batman-adv header 648 * @key_control: flow dissectors control key 649 * @data: raw buffer pointer to the packet, if NULL use skb->data 650 * @p_proto: pointer used to update the protocol to process next 651 * @p_nhoff: pointer used to update inner network header offset 652 * @hlen: packet header length 653 * @flags: any combination of FLOW_DISSECTOR_F_* 654 * 655 * ETH_P_BATMAN packets are tried to be dissected. Only 656 * &struct batadv_unicast packets are actually processed because they contain an 657 * inner ethernet header and are usually followed by actual network header. This 658 * allows the flow dissector to continue processing the packet. 659 * 660 * Return: FLOW_DISSECT_RET_PROTO_AGAIN when &struct batadv_unicast was found, 661 * FLOW_DISSECT_RET_OUT_GOOD when dissector should stop after encapsulation, 662 * otherwise FLOW_DISSECT_RET_OUT_BAD 663 */ 664 static enum flow_dissect_ret 665 __skb_flow_dissect_batadv(const struct sk_buff *skb, 666 struct flow_dissector_key_control *key_control, 667 const void *data, __be16 *p_proto, int *p_nhoff, 668 int hlen, unsigned int flags) 669 { 670 struct { 671 struct batadv_unicast_packet batadv_unicast; 672 struct ethhdr eth; 673 } *hdr, _hdr; 674 675 hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), data, hlen, 676 &_hdr); 677 if (!hdr) 678 return FLOW_DISSECT_RET_OUT_BAD; 679 680 if (hdr->batadv_unicast.version != BATADV_COMPAT_VERSION) 681 return FLOW_DISSECT_RET_OUT_BAD; 682 683 if (hdr->batadv_unicast.packet_type != BATADV_UNICAST) 684 return FLOW_DISSECT_RET_OUT_BAD; 685 686 *p_proto = hdr->eth.h_proto; 687 *p_nhoff += sizeof(*hdr); 688 689 key_control->flags |= FLOW_DIS_ENCAPSULATION; 690 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) 691 return FLOW_DISSECT_RET_OUT_GOOD; 692 693 return FLOW_DISSECT_RET_PROTO_AGAIN; 694 } 695 696 static void 697 __skb_flow_dissect_tcp(const struct sk_buff *skb, 698 struct flow_dissector *flow_dissector, 699 void *target_container, const void *data, 700 int thoff, int hlen) 701 { 702 struct flow_dissector_key_tcp *key_tcp; 703 struct tcphdr *th, _th; 704 705 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_TCP)) 706 return; 707 708 th = __skb_header_pointer(skb, thoff, sizeof(_th), data, hlen, &_th); 709 if (!th) 710 return; 711 712 if (unlikely(__tcp_hdrlen(th) < sizeof(_th))) 713 return; 714 715 key_tcp = skb_flow_dissector_target(flow_dissector, 716 FLOW_DISSECTOR_KEY_TCP, 717 target_container); 718 key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); 719 } 720 721 static void 722 __skb_flow_dissect_ports(const struct sk_buff *skb, 723 struct flow_dissector *flow_dissector, 724 void *target_container, const void *data, 725 int nhoff, u8 ip_proto, int hlen) 726 { 727 enum flow_dissector_key_id dissector_ports = FLOW_DISSECTOR_KEY_MAX; 728 struct flow_dissector_key_ports *key_ports; 729 730 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS)) 731 dissector_ports = FLOW_DISSECTOR_KEY_PORTS; 732 else if (dissector_uses_key(flow_dissector, 733 FLOW_DISSECTOR_KEY_PORTS_RANGE)) 734 dissector_ports = FLOW_DISSECTOR_KEY_PORTS_RANGE; 735 736 if (dissector_ports == FLOW_DISSECTOR_KEY_MAX) 737 return; 738 739 key_ports = skb_flow_dissector_target(flow_dissector, 740 dissector_ports, 741 target_container); 742 key_ports->ports = __skb_flow_get_ports(skb, nhoff, ip_proto, 743 data, hlen); 744 } 745 746 static void 747 __skb_flow_dissect_ipv4(const struct sk_buff *skb, 748 struct flow_dissector *flow_dissector, 749 void *target_container, const void *data, 750 const struct iphdr *iph) 751 { 752 struct flow_dissector_key_ip *key_ip; 753 754 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP)) 755 return; 756 757 key_ip = skb_flow_dissector_target(flow_dissector, 758 FLOW_DISSECTOR_KEY_IP, 759 target_container); 760 key_ip->tos = iph->tos; 761 key_ip->ttl = iph->ttl; 762 } 763 764 static void 765 __skb_flow_dissect_ipv6(const struct sk_buff *skb, 766 struct flow_dissector *flow_dissector, 767 void *target_container, const void *data, 768 const struct ipv6hdr *iph) 769 { 770 struct flow_dissector_key_ip *key_ip; 771 772 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP)) 773 return; 774 775 key_ip = skb_flow_dissector_target(flow_dissector, 776 FLOW_DISSECTOR_KEY_IP, 777 target_container); 778 key_ip->tos = ipv6_get_dsfield(iph); 779 key_ip->ttl = iph->hop_limit; 780 } 781 782 /* Maximum number of protocol headers that can be parsed in 783 * __skb_flow_dissect 784 */ 785 #define MAX_FLOW_DISSECT_HDRS 15 786 787 static bool skb_flow_dissect_allowed(int *num_hdrs) 788 { 789 ++*num_hdrs; 790 791 return (*num_hdrs <= MAX_FLOW_DISSECT_HDRS); 792 } 793 794 static void __skb_flow_bpf_to_target(const struct bpf_flow_keys *flow_keys, 795 struct flow_dissector *flow_dissector, 796 void *target_container) 797 { 798 struct flow_dissector_key_ports *key_ports = NULL; 799 struct flow_dissector_key_control *key_control; 800 struct flow_dissector_key_basic *key_basic; 801 struct flow_dissector_key_addrs *key_addrs; 802 struct flow_dissector_key_tags *key_tags; 803 804 key_control = skb_flow_dissector_target(flow_dissector, 805 FLOW_DISSECTOR_KEY_CONTROL, 806 target_container); 807 key_control->thoff = flow_keys->thoff; 808 if (flow_keys->is_frag) 809 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 810 if (flow_keys->is_first_frag) 811 key_control->flags |= FLOW_DIS_FIRST_FRAG; 812 if (flow_keys->is_encap) 813 key_control->flags |= FLOW_DIS_ENCAPSULATION; 814 815 key_basic = skb_flow_dissector_target(flow_dissector, 816 FLOW_DISSECTOR_KEY_BASIC, 817 target_container); 818 key_basic->n_proto = flow_keys->n_proto; 819 key_basic->ip_proto = flow_keys->ip_proto; 820 821 if (flow_keys->addr_proto == ETH_P_IP && 822 dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IPV4_ADDRS)) { 823 key_addrs = skb_flow_dissector_target(flow_dissector, 824 FLOW_DISSECTOR_KEY_IPV4_ADDRS, 825 target_container); 826 key_addrs->v4addrs.src = flow_keys->ipv4_src; 827 key_addrs->v4addrs.dst = flow_keys->ipv4_dst; 828 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS; 829 } else if (flow_keys->addr_proto == ETH_P_IPV6 && 830 dissector_uses_key(flow_dissector, 831 FLOW_DISSECTOR_KEY_IPV6_ADDRS)) { 832 key_addrs = skb_flow_dissector_target(flow_dissector, 833 FLOW_DISSECTOR_KEY_IPV6_ADDRS, 834 target_container); 835 memcpy(&key_addrs->v6addrs.src, &flow_keys->ipv6_src, 836 sizeof(key_addrs->v6addrs.src)); 837 memcpy(&key_addrs->v6addrs.dst, &flow_keys->ipv6_dst, 838 sizeof(key_addrs->v6addrs.dst)); 839 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 840 } 841 842 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS)) 843 key_ports = skb_flow_dissector_target(flow_dissector, 844 FLOW_DISSECTOR_KEY_PORTS, 845 target_container); 846 else if (dissector_uses_key(flow_dissector, 847 FLOW_DISSECTOR_KEY_PORTS_RANGE)) 848 key_ports = skb_flow_dissector_target(flow_dissector, 849 FLOW_DISSECTOR_KEY_PORTS_RANGE, 850 target_container); 851 852 if (key_ports) { 853 key_ports->src = flow_keys->sport; 854 key_ports->dst = flow_keys->dport; 855 } 856 857 if (dissector_uses_key(flow_dissector, 858 FLOW_DISSECTOR_KEY_FLOW_LABEL)) { 859 key_tags = skb_flow_dissector_target(flow_dissector, 860 FLOW_DISSECTOR_KEY_FLOW_LABEL, 861 target_container); 862 key_tags->flow_label = ntohl(flow_keys->flow_label); 863 } 864 } 865 866 bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx, 867 __be16 proto, int nhoff, int hlen, unsigned int flags) 868 { 869 struct bpf_flow_keys *flow_keys = ctx->flow_keys; 870 u32 result; 871 872 /* Pass parameters to the BPF program */ 873 memset(flow_keys, 0, sizeof(*flow_keys)); 874 flow_keys->n_proto = proto; 875 flow_keys->nhoff = nhoff; 876 flow_keys->thoff = flow_keys->nhoff; 877 878 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG != 879 (int)FLOW_DISSECTOR_F_PARSE_1ST_FRAG); 880 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL != 881 (int)FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 882 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP != 883 (int)FLOW_DISSECTOR_F_STOP_AT_ENCAP); 884 flow_keys->flags = flags; 885 886 result = bpf_prog_run_pin_on_cpu(prog, ctx); 887 888 flow_keys->nhoff = clamp_t(u16, flow_keys->nhoff, nhoff, hlen); 889 flow_keys->thoff = clamp_t(u16, flow_keys->thoff, 890 flow_keys->nhoff, hlen); 891 892 return result == BPF_OK; 893 } 894 895 /** 896 * __skb_flow_dissect - extract the flow_keys struct and return it 897 * @net: associated network namespace, derived from @skb if NULL 898 * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified 899 * @flow_dissector: list of keys to dissect 900 * @target_container: target structure to put dissected values into 901 * @data: raw buffer pointer to the packet, if NULL use skb->data 902 * @proto: protocol for which to get the flow, if @data is NULL use skb->protocol 903 * @nhoff: network header offset, if @data is NULL use skb_network_offset(skb) 904 * @hlen: packet header length, if @data is NULL use skb_headlen(skb) 905 * @flags: flags that control the dissection process, e.g. 906 * FLOW_DISSECTOR_F_STOP_AT_ENCAP. 907 * 908 * The function will try to retrieve individual keys into target specified 909 * by flow_dissector from either the skbuff or a raw buffer specified by the 910 * rest parameters. 911 * 912 * Caller must take care of zeroing target container memory. 913 */ 914 bool __skb_flow_dissect(const struct net *net, 915 const struct sk_buff *skb, 916 struct flow_dissector *flow_dissector, 917 void *target_container, const void *data, 918 __be16 proto, int nhoff, int hlen, unsigned int flags) 919 { 920 struct flow_dissector_key_control *key_control; 921 struct flow_dissector_key_basic *key_basic; 922 struct flow_dissector_key_addrs *key_addrs; 923 struct flow_dissector_key_tags *key_tags; 924 struct flow_dissector_key_vlan *key_vlan; 925 enum flow_dissect_ret fdret; 926 enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX; 927 bool mpls_el = false; 928 int mpls_lse = 0; 929 int num_hdrs = 0; 930 u8 ip_proto = 0; 931 bool ret; 932 933 if (!data) { 934 data = skb->data; 935 proto = skb_vlan_tag_present(skb) ? 936 skb->vlan_proto : skb->protocol; 937 nhoff = skb_network_offset(skb); 938 hlen = skb_headlen(skb); 939 #if IS_ENABLED(CONFIG_NET_DSA) 940 if (unlikely(skb->dev && netdev_uses_dsa(skb->dev) && 941 proto == htons(ETH_P_XDSA))) { 942 const struct dsa_device_ops *ops; 943 int offset = 0; 944 945 ops = skb->dev->dsa_ptr->tag_ops; 946 /* Only DSA header taggers break flow dissection */ 947 if (ops->needed_headroom) { 948 if (ops->flow_dissect) 949 ops->flow_dissect(skb, &proto, &offset); 950 else 951 dsa_tag_generic_flow_dissect(skb, 952 &proto, 953 &offset); 954 hlen -= offset; 955 nhoff += offset; 956 } 957 } 958 #endif 959 } 960 961 /* It is ensured by skb_flow_dissector_init() that control key will 962 * be always present. 963 */ 964 key_control = skb_flow_dissector_target(flow_dissector, 965 FLOW_DISSECTOR_KEY_CONTROL, 966 target_container); 967 968 /* It is ensured by skb_flow_dissector_init() that basic key will 969 * be always present. 970 */ 971 key_basic = skb_flow_dissector_target(flow_dissector, 972 FLOW_DISSECTOR_KEY_BASIC, 973 target_container); 974 975 if (skb) { 976 if (!net) { 977 if (skb->dev) 978 net = dev_net(skb->dev); 979 else if (skb->sk) 980 net = sock_net(skb->sk); 981 } 982 } 983 984 WARN_ON_ONCE(!net); 985 if (net) { 986 enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR; 987 struct bpf_prog_array *run_array; 988 989 rcu_read_lock(); 990 run_array = rcu_dereference(init_net.bpf.run_array[type]); 991 if (!run_array) 992 run_array = rcu_dereference(net->bpf.run_array[type]); 993 994 if (run_array) { 995 struct bpf_flow_keys flow_keys; 996 struct bpf_flow_dissector ctx = { 997 .flow_keys = &flow_keys, 998 .data = data, 999 .data_end = data + hlen, 1000 }; 1001 __be16 n_proto = proto; 1002 struct bpf_prog *prog; 1003 1004 if (skb) { 1005 ctx.skb = skb; 1006 /* we can't use 'proto' in the skb case 1007 * because it might be set to skb->vlan_proto 1008 * which has been pulled from the data 1009 */ 1010 n_proto = skb->protocol; 1011 } 1012 1013 prog = READ_ONCE(run_array->items[0].prog); 1014 ret = bpf_flow_dissect(prog, &ctx, n_proto, nhoff, 1015 hlen, flags); 1016 __skb_flow_bpf_to_target(&flow_keys, flow_dissector, 1017 target_container); 1018 rcu_read_unlock(); 1019 return ret; 1020 } 1021 rcu_read_unlock(); 1022 } 1023 1024 if (dissector_uses_key(flow_dissector, 1025 FLOW_DISSECTOR_KEY_ETH_ADDRS)) { 1026 struct ethhdr *eth = eth_hdr(skb); 1027 struct flow_dissector_key_eth_addrs *key_eth_addrs; 1028 1029 key_eth_addrs = skb_flow_dissector_target(flow_dissector, 1030 FLOW_DISSECTOR_KEY_ETH_ADDRS, 1031 target_container); 1032 memcpy(key_eth_addrs, ð->h_dest, sizeof(*key_eth_addrs)); 1033 } 1034 1035 proto_again: 1036 fdret = FLOW_DISSECT_RET_CONTINUE; 1037 1038 switch (proto) { 1039 case htons(ETH_P_IP): { 1040 const struct iphdr *iph; 1041 struct iphdr _iph; 1042 1043 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); 1044 if (!iph || iph->ihl < 5) { 1045 fdret = FLOW_DISSECT_RET_OUT_BAD; 1046 break; 1047 } 1048 1049 nhoff += iph->ihl * 4; 1050 1051 ip_proto = iph->protocol; 1052 1053 if (dissector_uses_key(flow_dissector, 1054 FLOW_DISSECTOR_KEY_IPV4_ADDRS)) { 1055 key_addrs = skb_flow_dissector_target(flow_dissector, 1056 FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1057 target_container); 1058 1059 memcpy(&key_addrs->v4addrs, &iph->saddr, 1060 sizeof(key_addrs->v4addrs)); 1061 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS; 1062 } 1063 1064 __skb_flow_dissect_ipv4(skb, flow_dissector, 1065 target_container, data, iph); 1066 1067 if (ip_is_fragment(iph)) { 1068 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 1069 1070 if (iph->frag_off & htons(IP_OFFSET)) { 1071 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1072 break; 1073 } else { 1074 key_control->flags |= FLOW_DIS_FIRST_FRAG; 1075 if (!(flags & 1076 FLOW_DISSECTOR_F_PARSE_1ST_FRAG)) { 1077 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1078 break; 1079 } 1080 } 1081 } 1082 1083 break; 1084 } 1085 case htons(ETH_P_IPV6): { 1086 const struct ipv6hdr *iph; 1087 struct ipv6hdr _iph; 1088 1089 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); 1090 if (!iph) { 1091 fdret = FLOW_DISSECT_RET_OUT_BAD; 1092 break; 1093 } 1094 1095 ip_proto = iph->nexthdr; 1096 nhoff += sizeof(struct ipv6hdr); 1097 1098 if (dissector_uses_key(flow_dissector, 1099 FLOW_DISSECTOR_KEY_IPV6_ADDRS)) { 1100 key_addrs = skb_flow_dissector_target(flow_dissector, 1101 FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1102 target_container); 1103 1104 memcpy(&key_addrs->v6addrs, &iph->saddr, 1105 sizeof(key_addrs->v6addrs)); 1106 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 1107 } 1108 1109 if ((dissector_uses_key(flow_dissector, 1110 FLOW_DISSECTOR_KEY_FLOW_LABEL) || 1111 (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)) && 1112 ip6_flowlabel(iph)) { 1113 __be32 flow_label = ip6_flowlabel(iph); 1114 1115 if (dissector_uses_key(flow_dissector, 1116 FLOW_DISSECTOR_KEY_FLOW_LABEL)) { 1117 key_tags = skb_flow_dissector_target(flow_dissector, 1118 FLOW_DISSECTOR_KEY_FLOW_LABEL, 1119 target_container); 1120 key_tags->flow_label = ntohl(flow_label); 1121 } 1122 if (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL) { 1123 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1124 break; 1125 } 1126 } 1127 1128 __skb_flow_dissect_ipv6(skb, flow_dissector, 1129 target_container, data, iph); 1130 1131 break; 1132 } 1133 case htons(ETH_P_8021AD): 1134 case htons(ETH_P_8021Q): { 1135 const struct vlan_hdr *vlan = NULL; 1136 struct vlan_hdr _vlan; 1137 __be16 saved_vlan_tpid = proto; 1138 1139 if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX && 1140 skb && skb_vlan_tag_present(skb)) { 1141 proto = skb->protocol; 1142 } else { 1143 vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan), 1144 data, hlen, &_vlan); 1145 if (!vlan) { 1146 fdret = FLOW_DISSECT_RET_OUT_BAD; 1147 break; 1148 } 1149 1150 proto = vlan->h_vlan_encapsulated_proto; 1151 nhoff += sizeof(*vlan); 1152 } 1153 1154 if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) { 1155 dissector_vlan = FLOW_DISSECTOR_KEY_VLAN; 1156 } else if (dissector_vlan == FLOW_DISSECTOR_KEY_VLAN) { 1157 dissector_vlan = FLOW_DISSECTOR_KEY_CVLAN; 1158 } else { 1159 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1160 break; 1161 } 1162 1163 if (dissector_uses_key(flow_dissector, dissector_vlan)) { 1164 key_vlan = skb_flow_dissector_target(flow_dissector, 1165 dissector_vlan, 1166 target_container); 1167 1168 if (!vlan) { 1169 key_vlan->vlan_id = skb_vlan_tag_get_id(skb); 1170 key_vlan->vlan_priority = skb_vlan_tag_get_prio(skb); 1171 } else { 1172 key_vlan->vlan_id = ntohs(vlan->h_vlan_TCI) & 1173 VLAN_VID_MASK; 1174 key_vlan->vlan_priority = 1175 (ntohs(vlan->h_vlan_TCI) & 1176 VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT; 1177 } 1178 key_vlan->vlan_tpid = saved_vlan_tpid; 1179 } 1180 1181 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1182 break; 1183 } 1184 case htons(ETH_P_PPP_SES): { 1185 struct { 1186 struct pppoe_hdr hdr; 1187 __be16 proto; 1188 } *hdr, _hdr; 1189 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr); 1190 if (!hdr) { 1191 fdret = FLOW_DISSECT_RET_OUT_BAD; 1192 break; 1193 } 1194 1195 proto = hdr->proto; 1196 nhoff += PPPOE_SES_HLEN; 1197 switch (proto) { 1198 case htons(PPP_IP): 1199 proto = htons(ETH_P_IP); 1200 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1201 break; 1202 case htons(PPP_IPV6): 1203 proto = htons(ETH_P_IPV6); 1204 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1205 break; 1206 default: 1207 fdret = FLOW_DISSECT_RET_OUT_BAD; 1208 break; 1209 } 1210 break; 1211 } 1212 case htons(ETH_P_TIPC): { 1213 struct tipc_basic_hdr *hdr, _hdr; 1214 1215 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), 1216 data, hlen, &_hdr); 1217 if (!hdr) { 1218 fdret = FLOW_DISSECT_RET_OUT_BAD; 1219 break; 1220 } 1221 1222 if (dissector_uses_key(flow_dissector, 1223 FLOW_DISSECTOR_KEY_TIPC)) { 1224 key_addrs = skb_flow_dissector_target(flow_dissector, 1225 FLOW_DISSECTOR_KEY_TIPC, 1226 target_container); 1227 key_addrs->tipckey.key = tipc_hdr_rps_key(hdr); 1228 key_control->addr_type = FLOW_DISSECTOR_KEY_TIPC; 1229 } 1230 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1231 break; 1232 } 1233 1234 case htons(ETH_P_MPLS_UC): 1235 case htons(ETH_P_MPLS_MC): 1236 fdret = __skb_flow_dissect_mpls(skb, flow_dissector, 1237 target_container, data, 1238 nhoff, hlen, mpls_lse, 1239 &mpls_el); 1240 nhoff += sizeof(struct mpls_label); 1241 mpls_lse++; 1242 break; 1243 case htons(ETH_P_FCOE): 1244 if ((hlen - nhoff) < FCOE_HEADER_LEN) { 1245 fdret = FLOW_DISSECT_RET_OUT_BAD; 1246 break; 1247 } 1248 1249 nhoff += FCOE_HEADER_LEN; 1250 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1251 break; 1252 1253 case htons(ETH_P_ARP): 1254 case htons(ETH_P_RARP): 1255 fdret = __skb_flow_dissect_arp(skb, flow_dissector, 1256 target_container, data, 1257 nhoff, hlen); 1258 break; 1259 1260 case htons(ETH_P_BATMAN): 1261 fdret = __skb_flow_dissect_batadv(skb, key_control, data, 1262 &proto, &nhoff, hlen, flags); 1263 break; 1264 1265 case htons(ETH_P_1588): { 1266 struct ptp_header *hdr, _hdr; 1267 1268 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, 1269 hlen, &_hdr); 1270 if (!hdr) { 1271 fdret = FLOW_DISSECT_RET_OUT_BAD; 1272 break; 1273 } 1274 1275 nhoff += ntohs(hdr->message_length); 1276 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1277 break; 1278 } 1279 1280 default: 1281 fdret = FLOW_DISSECT_RET_OUT_BAD; 1282 break; 1283 } 1284 1285 /* Process result of proto processing */ 1286 switch (fdret) { 1287 case FLOW_DISSECT_RET_OUT_GOOD: 1288 goto out_good; 1289 case FLOW_DISSECT_RET_PROTO_AGAIN: 1290 if (skb_flow_dissect_allowed(&num_hdrs)) 1291 goto proto_again; 1292 goto out_good; 1293 case FLOW_DISSECT_RET_CONTINUE: 1294 case FLOW_DISSECT_RET_IPPROTO_AGAIN: 1295 break; 1296 case FLOW_DISSECT_RET_OUT_BAD: 1297 default: 1298 goto out_bad; 1299 } 1300 1301 ip_proto_again: 1302 fdret = FLOW_DISSECT_RET_CONTINUE; 1303 1304 switch (ip_proto) { 1305 case IPPROTO_GRE: 1306 fdret = __skb_flow_dissect_gre(skb, key_control, flow_dissector, 1307 target_container, data, 1308 &proto, &nhoff, &hlen, flags); 1309 break; 1310 1311 case NEXTHDR_HOP: 1312 case NEXTHDR_ROUTING: 1313 case NEXTHDR_DEST: { 1314 u8 _opthdr[2], *opthdr; 1315 1316 if (proto != htons(ETH_P_IPV6)) 1317 break; 1318 1319 opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr), 1320 data, hlen, &_opthdr); 1321 if (!opthdr) { 1322 fdret = FLOW_DISSECT_RET_OUT_BAD; 1323 break; 1324 } 1325 1326 ip_proto = opthdr[0]; 1327 nhoff += (opthdr[1] + 1) << 3; 1328 1329 fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN; 1330 break; 1331 } 1332 case NEXTHDR_FRAGMENT: { 1333 struct frag_hdr _fh, *fh; 1334 1335 if (proto != htons(ETH_P_IPV6)) 1336 break; 1337 1338 fh = __skb_header_pointer(skb, nhoff, sizeof(_fh), 1339 data, hlen, &_fh); 1340 1341 if (!fh) { 1342 fdret = FLOW_DISSECT_RET_OUT_BAD; 1343 break; 1344 } 1345 1346 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 1347 1348 nhoff += sizeof(_fh); 1349 ip_proto = fh->nexthdr; 1350 1351 if (!(fh->frag_off & htons(IP6_OFFSET))) { 1352 key_control->flags |= FLOW_DIS_FIRST_FRAG; 1353 if (flags & FLOW_DISSECTOR_F_PARSE_1ST_FRAG) { 1354 fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN; 1355 break; 1356 } 1357 } 1358 1359 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1360 break; 1361 } 1362 case IPPROTO_IPIP: 1363 proto = htons(ETH_P_IP); 1364 1365 key_control->flags |= FLOW_DIS_ENCAPSULATION; 1366 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) { 1367 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1368 break; 1369 } 1370 1371 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1372 break; 1373 1374 case IPPROTO_IPV6: 1375 proto = htons(ETH_P_IPV6); 1376 1377 key_control->flags |= FLOW_DIS_ENCAPSULATION; 1378 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) { 1379 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1380 break; 1381 } 1382 1383 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1384 break; 1385 1386 1387 case IPPROTO_MPLS: 1388 proto = htons(ETH_P_MPLS_UC); 1389 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1390 break; 1391 1392 case IPPROTO_TCP: 1393 __skb_flow_dissect_tcp(skb, flow_dissector, target_container, 1394 data, nhoff, hlen); 1395 break; 1396 1397 case IPPROTO_ICMP: 1398 case IPPROTO_ICMPV6: 1399 __skb_flow_dissect_icmp(skb, flow_dissector, target_container, 1400 data, nhoff, hlen); 1401 break; 1402 1403 default: 1404 break; 1405 } 1406 1407 if (!(key_control->flags & FLOW_DIS_IS_FRAGMENT)) 1408 __skb_flow_dissect_ports(skb, flow_dissector, target_container, 1409 data, nhoff, ip_proto, hlen); 1410 1411 /* Process result of IP proto processing */ 1412 switch (fdret) { 1413 case FLOW_DISSECT_RET_PROTO_AGAIN: 1414 if (skb_flow_dissect_allowed(&num_hdrs)) 1415 goto proto_again; 1416 break; 1417 case FLOW_DISSECT_RET_IPPROTO_AGAIN: 1418 if (skb_flow_dissect_allowed(&num_hdrs)) 1419 goto ip_proto_again; 1420 break; 1421 case FLOW_DISSECT_RET_OUT_GOOD: 1422 case FLOW_DISSECT_RET_CONTINUE: 1423 break; 1424 case FLOW_DISSECT_RET_OUT_BAD: 1425 default: 1426 goto out_bad; 1427 } 1428 1429 out_good: 1430 ret = true; 1431 1432 out: 1433 key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); 1434 key_basic->n_proto = proto; 1435 key_basic->ip_proto = ip_proto; 1436 1437 return ret; 1438 1439 out_bad: 1440 ret = false; 1441 goto out; 1442 } 1443 EXPORT_SYMBOL(__skb_flow_dissect); 1444 1445 static siphash_key_t hashrnd __read_mostly; 1446 static __always_inline void __flow_hash_secret_init(void) 1447 { 1448 net_get_random_once(&hashrnd, sizeof(hashrnd)); 1449 } 1450 1451 static const void *flow_keys_hash_start(const struct flow_keys *flow) 1452 { 1453 BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % SIPHASH_ALIGNMENT); 1454 return &flow->FLOW_KEYS_HASH_START_FIELD; 1455 } 1456 1457 static inline size_t flow_keys_hash_length(const struct flow_keys *flow) 1458 { 1459 size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs); 1460 1461 BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32)); 1462 1463 switch (flow->control.addr_type) { 1464 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1465 diff -= sizeof(flow->addrs.v4addrs); 1466 break; 1467 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1468 diff -= sizeof(flow->addrs.v6addrs); 1469 break; 1470 case FLOW_DISSECTOR_KEY_TIPC: 1471 diff -= sizeof(flow->addrs.tipckey); 1472 break; 1473 } 1474 return sizeof(*flow) - diff; 1475 } 1476 1477 __be32 flow_get_u32_src(const struct flow_keys *flow) 1478 { 1479 switch (flow->control.addr_type) { 1480 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1481 return flow->addrs.v4addrs.src; 1482 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1483 return (__force __be32)ipv6_addr_hash( 1484 &flow->addrs.v6addrs.src); 1485 case FLOW_DISSECTOR_KEY_TIPC: 1486 return flow->addrs.tipckey.key; 1487 default: 1488 return 0; 1489 } 1490 } 1491 EXPORT_SYMBOL(flow_get_u32_src); 1492 1493 __be32 flow_get_u32_dst(const struct flow_keys *flow) 1494 { 1495 switch (flow->control.addr_type) { 1496 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1497 return flow->addrs.v4addrs.dst; 1498 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1499 return (__force __be32)ipv6_addr_hash( 1500 &flow->addrs.v6addrs.dst); 1501 default: 1502 return 0; 1503 } 1504 } 1505 EXPORT_SYMBOL(flow_get_u32_dst); 1506 1507 /* Sort the source and destination IP and the ports, 1508 * to have consistent hash within the two directions 1509 */ 1510 static inline void __flow_hash_consistentify(struct flow_keys *keys) 1511 { 1512 int addr_diff, i; 1513 1514 switch (keys->control.addr_type) { 1515 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1516 addr_diff = (__force u32)keys->addrs.v4addrs.dst - 1517 (__force u32)keys->addrs.v4addrs.src; 1518 if (addr_diff < 0) 1519 swap(keys->addrs.v4addrs.src, keys->addrs.v4addrs.dst); 1520 1521 if ((__force u16)keys->ports.dst < 1522 (__force u16)keys->ports.src) { 1523 swap(keys->ports.src, keys->ports.dst); 1524 } 1525 break; 1526 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1527 addr_diff = memcmp(&keys->addrs.v6addrs.dst, 1528 &keys->addrs.v6addrs.src, 1529 sizeof(keys->addrs.v6addrs.dst)); 1530 if (addr_diff < 0) { 1531 for (i = 0; i < 4; i++) 1532 swap(keys->addrs.v6addrs.src.s6_addr32[i], 1533 keys->addrs.v6addrs.dst.s6_addr32[i]); 1534 } 1535 if ((__force u16)keys->ports.dst < 1536 (__force u16)keys->ports.src) { 1537 swap(keys->ports.src, keys->ports.dst); 1538 } 1539 break; 1540 } 1541 } 1542 1543 static inline u32 __flow_hash_from_keys(struct flow_keys *keys, 1544 const siphash_key_t *keyval) 1545 { 1546 u32 hash; 1547 1548 __flow_hash_consistentify(keys); 1549 1550 hash = siphash(flow_keys_hash_start(keys), 1551 flow_keys_hash_length(keys), keyval); 1552 if (!hash) 1553 hash = 1; 1554 1555 return hash; 1556 } 1557 1558 u32 flow_hash_from_keys(struct flow_keys *keys) 1559 { 1560 __flow_hash_secret_init(); 1561 return __flow_hash_from_keys(keys, &hashrnd); 1562 } 1563 EXPORT_SYMBOL(flow_hash_from_keys); 1564 1565 static inline u32 ___skb_get_hash(const struct sk_buff *skb, 1566 struct flow_keys *keys, 1567 const siphash_key_t *keyval) 1568 { 1569 skb_flow_dissect_flow_keys(skb, keys, 1570 FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 1571 1572 return __flow_hash_from_keys(keys, keyval); 1573 } 1574 1575 struct _flow_keys_digest_data { 1576 __be16 n_proto; 1577 u8 ip_proto; 1578 u8 padding; 1579 __be32 ports; 1580 __be32 src; 1581 __be32 dst; 1582 }; 1583 1584 void make_flow_keys_digest(struct flow_keys_digest *digest, 1585 const struct flow_keys *flow) 1586 { 1587 struct _flow_keys_digest_data *data = 1588 (struct _flow_keys_digest_data *)digest; 1589 1590 BUILD_BUG_ON(sizeof(*data) > sizeof(*digest)); 1591 1592 memset(digest, 0, sizeof(*digest)); 1593 1594 data->n_proto = flow->basic.n_proto; 1595 data->ip_proto = flow->basic.ip_proto; 1596 data->ports = flow->ports.ports; 1597 data->src = flow->addrs.v4addrs.src; 1598 data->dst = flow->addrs.v4addrs.dst; 1599 } 1600 EXPORT_SYMBOL(make_flow_keys_digest); 1601 1602 static struct flow_dissector flow_keys_dissector_symmetric __read_mostly; 1603 1604 u32 __skb_get_hash_symmetric(const struct sk_buff *skb) 1605 { 1606 struct flow_keys keys; 1607 1608 __flow_hash_secret_init(); 1609 1610 memset(&keys, 0, sizeof(keys)); 1611 __skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric, 1612 &keys, NULL, 0, 0, 0, 1613 FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 1614 1615 return __flow_hash_from_keys(&keys, &hashrnd); 1616 } 1617 EXPORT_SYMBOL_GPL(__skb_get_hash_symmetric); 1618 1619 /** 1620 * __skb_get_hash: calculate a flow hash 1621 * @skb: sk_buff to calculate flow hash from 1622 * 1623 * This function calculates a flow hash based on src/dst addresses 1624 * and src/dst port numbers. Sets hash in skb to non-zero hash value 1625 * on success, zero indicates no valid hash. Also, sets l4_hash in skb 1626 * if hash is a canonical 4-tuple hash over transport ports. 1627 */ 1628 void __skb_get_hash(struct sk_buff *skb) 1629 { 1630 struct flow_keys keys; 1631 u32 hash; 1632 1633 __flow_hash_secret_init(); 1634 1635 hash = ___skb_get_hash(skb, &keys, &hashrnd); 1636 1637 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys)); 1638 } 1639 EXPORT_SYMBOL(__skb_get_hash); 1640 1641 __u32 skb_get_hash_perturb(const struct sk_buff *skb, 1642 const siphash_key_t *perturb) 1643 { 1644 struct flow_keys keys; 1645 1646 return ___skb_get_hash(skb, &keys, perturb); 1647 } 1648 EXPORT_SYMBOL(skb_get_hash_perturb); 1649 1650 u32 __skb_get_poff(const struct sk_buff *skb, const void *data, 1651 const struct flow_keys_basic *keys, int hlen) 1652 { 1653 u32 poff = keys->control.thoff; 1654 1655 /* skip L4 headers for fragments after the first */ 1656 if ((keys->control.flags & FLOW_DIS_IS_FRAGMENT) && 1657 !(keys->control.flags & FLOW_DIS_FIRST_FRAG)) 1658 return poff; 1659 1660 switch (keys->basic.ip_proto) { 1661 case IPPROTO_TCP: { 1662 /* access doff as u8 to avoid unaligned access */ 1663 const u8 *doff; 1664 u8 _doff; 1665 1666 doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff), 1667 data, hlen, &_doff); 1668 if (!doff) 1669 return poff; 1670 1671 poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2); 1672 break; 1673 } 1674 case IPPROTO_UDP: 1675 case IPPROTO_UDPLITE: 1676 poff += sizeof(struct udphdr); 1677 break; 1678 /* For the rest, we do not really care about header 1679 * extensions at this point for now. 1680 */ 1681 case IPPROTO_ICMP: 1682 poff += sizeof(struct icmphdr); 1683 break; 1684 case IPPROTO_ICMPV6: 1685 poff += sizeof(struct icmp6hdr); 1686 break; 1687 case IPPROTO_IGMP: 1688 poff += sizeof(struct igmphdr); 1689 break; 1690 case IPPROTO_DCCP: 1691 poff += sizeof(struct dccp_hdr); 1692 break; 1693 case IPPROTO_SCTP: 1694 poff += sizeof(struct sctphdr); 1695 break; 1696 } 1697 1698 return poff; 1699 } 1700 1701 /** 1702 * skb_get_poff - get the offset to the payload 1703 * @skb: sk_buff to get the payload offset from 1704 * 1705 * The function will get the offset to the payload as far as it could 1706 * be dissected. The main user is currently BPF, so that we can dynamically 1707 * truncate packets without needing to push actual payload to the user 1708 * space and can analyze headers only, instead. 1709 */ 1710 u32 skb_get_poff(const struct sk_buff *skb) 1711 { 1712 struct flow_keys_basic keys; 1713 1714 if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, 1715 NULL, 0, 0, 0, 0)) 1716 return 0; 1717 1718 return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb)); 1719 } 1720 1721 __u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys) 1722 { 1723 memset(keys, 0, sizeof(*keys)); 1724 1725 memcpy(&keys->addrs.v6addrs.src, &fl6->saddr, 1726 sizeof(keys->addrs.v6addrs.src)); 1727 memcpy(&keys->addrs.v6addrs.dst, &fl6->daddr, 1728 sizeof(keys->addrs.v6addrs.dst)); 1729 keys->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 1730 keys->ports.src = fl6->fl6_sport; 1731 keys->ports.dst = fl6->fl6_dport; 1732 keys->keyid.keyid = fl6->fl6_gre_key; 1733 keys->tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6); 1734 keys->basic.ip_proto = fl6->flowi6_proto; 1735 1736 return flow_hash_from_keys(keys); 1737 } 1738 EXPORT_SYMBOL(__get_hash_from_flowi6); 1739 1740 static const struct flow_dissector_key flow_keys_dissector_keys[] = { 1741 { 1742 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1743 .offset = offsetof(struct flow_keys, control), 1744 }, 1745 { 1746 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1747 .offset = offsetof(struct flow_keys, basic), 1748 }, 1749 { 1750 .key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1751 .offset = offsetof(struct flow_keys, addrs.v4addrs), 1752 }, 1753 { 1754 .key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1755 .offset = offsetof(struct flow_keys, addrs.v6addrs), 1756 }, 1757 { 1758 .key_id = FLOW_DISSECTOR_KEY_TIPC, 1759 .offset = offsetof(struct flow_keys, addrs.tipckey), 1760 }, 1761 { 1762 .key_id = FLOW_DISSECTOR_KEY_PORTS, 1763 .offset = offsetof(struct flow_keys, ports), 1764 }, 1765 { 1766 .key_id = FLOW_DISSECTOR_KEY_VLAN, 1767 .offset = offsetof(struct flow_keys, vlan), 1768 }, 1769 { 1770 .key_id = FLOW_DISSECTOR_KEY_FLOW_LABEL, 1771 .offset = offsetof(struct flow_keys, tags), 1772 }, 1773 { 1774 .key_id = FLOW_DISSECTOR_KEY_GRE_KEYID, 1775 .offset = offsetof(struct flow_keys, keyid), 1776 }, 1777 }; 1778 1779 static const struct flow_dissector_key flow_keys_dissector_symmetric_keys[] = { 1780 { 1781 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1782 .offset = offsetof(struct flow_keys, control), 1783 }, 1784 { 1785 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1786 .offset = offsetof(struct flow_keys, basic), 1787 }, 1788 { 1789 .key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1790 .offset = offsetof(struct flow_keys, addrs.v4addrs), 1791 }, 1792 { 1793 .key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1794 .offset = offsetof(struct flow_keys, addrs.v6addrs), 1795 }, 1796 { 1797 .key_id = FLOW_DISSECTOR_KEY_PORTS, 1798 .offset = offsetof(struct flow_keys, ports), 1799 }, 1800 }; 1801 1802 static const struct flow_dissector_key flow_keys_basic_dissector_keys[] = { 1803 { 1804 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1805 .offset = offsetof(struct flow_keys, control), 1806 }, 1807 { 1808 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1809 .offset = offsetof(struct flow_keys, basic), 1810 }, 1811 }; 1812 1813 struct flow_dissector flow_keys_dissector __read_mostly; 1814 EXPORT_SYMBOL(flow_keys_dissector); 1815 1816 struct flow_dissector flow_keys_basic_dissector __read_mostly; 1817 EXPORT_SYMBOL(flow_keys_basic_dissector); 1818 1819 static int __init init_default_flow_dissectors(void) 1820 { 1821 skb_flow_dissector_init(&flow_keys_dissector, 1822 flow_keys_dissector_keys, 1823 ARRAY_SIZE(flow_keys_dissector_keys)); 1824 skb_flow_dissector_init(&flow_keys_dissector_symmetric, 1825 flow_keys_dissector_symmetric_keys, 1826 ARRAY_SIZE(flow_keys_dissector_symmetric_keys)); 1827 skb_flow_dissector_init(&flow_keys_basic_dissector, 1828 flow_keys_basic_dissector_keys, 1829 ARRAY_SIZE(flow_keys_basic_dissector_keys)); 1830 return 0; 1831 } 1832 core_initcall(init_default_flow_dissectors); 1833