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 <net/flow_dissector.h> 27 #include <scsi/fc/fc_fcoe.h> 28 #include <uapi/linux/batadv_packet.h> 29 #include <linux/bpf.h> 30 #if IS_ENABLED(CONFIG_NF_CONNTRACK) 31 #include <net/netfilter/nf_conntrack_core.h> 32 #include <net/netfilter/nf_conntrack_labels.h> 33 #endif 34 35 static DEFINE_MUTEX(flow_dissector_mutex); 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 withing 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 int skb_flow_dissector_prog_query(const union bpf_attr *attr, 74 union bpf_attr __user *uattr) 75 { 76 __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids); 77 u32 prog_id, prog_cnt = 0, flags = 0; 78 struct bpf_prog *attached; 79 struct net *net; 80 81 if (attr->query.query_flags) 82 return -EINVAL; 83 84 net = get_net_ns_by_fd(attr->query.target_fd); 85 if (IS_ERR(net)) 86 return PTR_ERR(net); 87 88 rcu_read_lock(); 89 attached = rcu_dereference(net->flow_dissector_prog); 90 if (attached) { 91 prog_cnt = 1; 92 prog_id = attached->aux->id; 93 } 94 rcu_read_unlock(); 95 96 put_net(net); 97 98 if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) 99 return -EFAULT; 100 if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt))) 101 return -EFAULT; 102 103 if (!attr->query.prog_cnt || !prog_ids || !prog_cnt) 104 return 0; 105 106 if (copy_to_user(prog_ids, &prog_id, sizeof(u32))) 107 return -EFAULT; 108 109 return 0; 110 } 111 112 int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr, 113 struct bpf_prog *prog) 114 { 115 struct bpf_prog *attached; 116 struct net *net; 117 int ret = 0; 118 119 net = current->nsproxy->net_ns; 120 mutex_lock(&flow_dissector_mutex); 121 122 if (net == &init_net) { 123 /* BPF flow dissector in the root namespace overrides 124 * any per-net-namespace one. When attaching to root, 125 * make sure we don't have any BPF program attached 126 * to the non-root namespaces. 127 */ 128 struct net *ns; 129 130 for_each_net(ns) { 131 if (ns == &init_net) 132 continue; 133 if (rcu_access_pointer(ns->flow_dissector_prog)) { 134 ret = -EEXIST; 135 goto out; 136 } 137 } 138 } else { 139 /* Make sure root flow dissector is not attached 140 * when attaching to the non-root namespace. 141 */ 142 if (rcu_access_pointer(init_net.flow_dissector_prog)) { 143 ret = -EEXIST; 144 goto out; 145 } 146 } 147 148 attached = rcu_dereference_protected(net->flow_dissector_prog, 149 lockdep_is_held(&flow_dissector_mutex)); 150 if (attached == prog) { 151 /* The same program cannot be attached twice */ 152 ret = -EINVAL; 153 goto out; 154 } 155 rcu_assign_pointer(net->flow_dissector_prog, prog); 156 if (attached) 157 bpf_prog_put(attached); 158 out: 159 mutex_unlock(&flow_dissector_mutex); 160 return ret; 161 } 162 163 int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr) 164 { 165 struct bpf_prog *attached; 166 struct net *net; 167 168 net = current->nsproxy->net_ns; 169 mutex_lock(&flow_dissector_mutex); 170 attached = rcu_dereference_protected(net->flow_dissector_prog, 171 lockdep_is_held(&flow_dissector_mutex)); 172 if (!attached) { 173 mutex_unlock(&flow_dissector_mutex); 174 return -ENOENT; 175 } 176 RCU_INIT_POINTER(net->flow_dissector_prog, NULL); 177 bpf_prog_put(attached); 178 mutex_unlock(&flow_dissector_mutex); 179 return 0; 180 } 181 182 /** 183 * __skb_flow_get_ports - extract the upper layer ports and return them 184 * @skb: sk_buff to extract the ports from 185 * @thoff: transport header offset 186 * @ip_proto: protocol for which to get port offset 187 * @data: raw buffer pointer to the packet, if NULL use skb->data 188 * @hlen: packet header length, if @data is NULL use skb_headlen(skb) 189 * 190 * The function will try to retrieve the ports at offset thoff + poff where poff 191 * is the protocol port offset returned from proto_ports_offset 192 */ 193 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto, 194 void *data, int hlen) 195 { 196 int poff = proto_ports_offset(ip_proto); 197 198 if (!data) { 199 data = skb->data; 200 hlen = skb_headlen(skb); 201 } 202 203 if (poff >= 0) { 204 __be32 *ports, _ports; 205 206 ports = __skb_header_pointer(skb, thoff + poff, 207 sizeof(_ports), data, hlen, &_ports); 208 if (ports) 209 return *ports; 210 } 211 212 return 0; 213 } 214 EXPORT_SYMBOL(__skb_flow_get_ports); 215 216 static bool icmp_has_id(u8 type) 217 { 218 switch (type) { 219 case ICMP_ECHO: 220 case ICMP_ECHOREPLY: 221 case ICMP_TIMESTAMP: 222 case ICMP_TIMESTAMPREPLY: 223 case ICMPV6_ECHO_REQUEST: 224 case ICMPV6_ECHO_REPLY: 225 return true; 226 } 227 228 return false; 229 } 230 231 /** 232 * skb_flow_get_icmp_tci - extract ICMP(6) Type, Code and Identifier fields 233 * @skb: sk_buff to extract from 234 * @key_icmp: struct flow_dissector_key_icmp to fill 235 * @data: raw buffer pointer to the packet 236 * @thoff: offset to extract at 237 * @hlen: packet header length 238 */ 239 void skb_flow_get_icmp_tci(const struct sk_buff *skb, 240 struct flow_dissector_key_icmp *key_icmp, 241 void *data, int thoff, int hlen) 242 { 243 struct icmphdr *ih, _ih; 244 245 ih = __skb_header_pointer(skb, thoff, sizeof(_ih), data, hlen, &_ih); 246 if (!ih) 247 return; 248 249 key_icmp->type = ih->type; 250 key_icmp->code = ih->code; 251 252 /* As we use 0 to signal that the Id field is not present, 253 * avoid confusion with packets without such field 254 */ 255 if (icmp_has_id(ih->type)) 256 key_icmp->id = ih->un.echo.id ? : 1; 257 else 258 key_icmp->id = 0; 259 } 260 EXPORT_SYMBOL(skb_flow_get_icmp_tci); 261 262 /* If FLOW_DISSECTOR_KEY_ICMP is set, dissect an ICMP packet 263 * using skb_flow_get_icmp_tci(). 264 */ 265 static void __skb_flow_dissect_icmp(const struct sk_buff *skb, 266 struct flow_dissector *flow_dissector, 267 void *target_container, 268 void *data, int thoff, int hlen) 269 { 270 struct flow_dissector_key_icmp *key_icmp; 271 272 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ICMP)) 273 return; 274 275 key_icmp = skb_flow_dissector_target(flow_dissector, 276 FLOW_DISSECTOR_KEY_ICMP, 277 target_container); 278 279 skb_flow_get_icmp_tci(skb, key_icmp, data, thoff, hlen); 280 } 281 282 void skb_flow_dissect_meta(const struct sk_buff *skb, 283 struct flow_dissector *flow_dissector, 284 void *target_container) 285 { 286 struct flow_dissector_key_meta *meta; 287 288 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_META)) 289 return; 290 291 meta = skb_flow_dissector_target(flow_dissector, 292 FLOW_DISSECTOR_KEY_META, 293 target_container); 294 meta->ingress_ifindex = skb->skb_iif; 295 } 296 EXPORT_SYMBOL(skb_flow_dissect_meta); 297 298 static void 299 skb_flow_dissect_set_enc_addr_type(enum flow_dissector_key_id type, 300 struct flow_dissector *flow_dissector, 301 void *target_container) 302 { 303 struct flow_dissector_key_control *ctrl; 304 305 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_CONTROL)) 306 return; 307 308 ctrl = skb_flow_dissector_target(flow_dissector, 309 FLOW_DISSECTOR_KEY_ENC_CONTROL, 310 target_container); 311 ctrl->addr_type = type; 312 } 313 314 void 315 skb_flow_dissect_ct(const struct sk_buff *skb, 316 struct flow_dissector *flow_dissector, 317 void *target_container, 318 u16 *ctinfo_map, 319 size_t mapsize) 320 { 321 #if IS_ENABLED(CONFIG_NF_CONNTRACK) 322 struct flow_dissector_key_ct *key; 323 enum ip_conntrack_info ctinfo; 324 struct nf_conn_labels *cl; 325 struct nf_conn *ct; 326 327 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_CT)) 328 return; 329 330 ct = nf_ct_get(skb, &ctinfo); 331 if (!ct) 332 return; 333 334 key = skb_flow_dissector_target(flow_dissector, 335 FLOW_DISSECTOR_KEY_CT, 336 target_container); 337 338 if (ctinfo < mapsize) 339 key->ct_state = ctinfo_map[ctinfo]; 340 #if IS_ENABLED(CONFIG_NF_CONNTRACK_ZONES) 341 key->ct_zone = ct->zone.id; 342 #endif 343 #if IS_ENABLED(CONFIG_NF_CONNTRACK_MARK) 344 key->ct_mark = ct->mark; 345 #endif 346 347 cl = nf_ct_labels_find(ct); 348 if (cl) 349 memcpy(key->ct_labels, cl->bits, sizeof(key->ct_labels)); 350 #endif /* CONFIG_NF_CONNTRACK */ 351 } 352 EXPORT_SYMBOL(skb_flow_dissect_ct); 353 354 void 355 skb_flow_dissect_tunnel_info(const struct sk_buff *skb, 356 struct flow_dissector *flow_dissector, 357 void *target_container) 358 { 359 struct ip_tunnel_info *info; 360 struct ip_tunnel_key *key; 361 362 /* A quick check to see if there might be something to do. */ 363 if (!dissector_uses_key(flow_dissector, 364 FLOW_DISSECTOR_KEY_ENC_KEYID) && 365 !dissector_uses_key(flow_dissector, 366 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS) && 367 !dissector_uses_key(flow_dissector, 368 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS) && 369 !dissector_uses_key(flow_dissector, 370 FLOW_DISSECTOR_KEY_ENC_CONTROL) && 371 !dissector_uses_key(flow_dissector, 372 FLOW_DISSECTOR_KEY_ENC_PORTS) && 373 !dissector_uses_key(flow_dissector, 374 FLOW_DISSECTOR_KEY_ENC_IP) && 375 !dissector_uses_key(flow_dissector, 376 FLOW_DISSECTOR_KEY_ENC_OPTS)) 377 return; 378 379 info = skb_tunnel_info(skb); 380 if (!info) 381 return; 382 383 key = &info->key; 384 385 switch (ip_tunnel_info_af(info)) { 386 case AF_INET: 387 skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV4_ADDRS, 388 flow_dissector, 389 target_container); 390 if (dissector_uses_key(flow_dissector, 391 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS)) { 392 struct flow_dissector_key_ipv4_addrs *ipv4; 393 394 ipv4 = skb_flow_dissector_target(flow_dissector, 395 FLOW_DISSECTOR_KEY_ENC_IPV4_ADDRS, 396 target_container); 397 ipv4->src = key->u.ipv4.src; 398 ipv4->dst = key->u.ipv4.dst; 399 } 400 break; 401 case AF_INET6: 402 skb_flow_dissect_set_enc_addr_type(FLOW_DISSECTOR_KEY_IPV6_ADDRS, 403 flow_dissector, 404 target_container); 405 if (dissector_uses_key(flow_dissector, 406 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS)) { 407 struct flow_dissector_key_ipv6_addrs *ipv6; 408 409 ipv6 = skb_flow_dissector_target(flow_dissector, 410 FLOW_DISSECTOR_KEY_ENC_IPV6_ADDRS, 411 target_container); 412 ipv6->src = key->u.ipv6.src; 413 ipv6->dst = key->u.ipv6.dst; 414 } 415 break; 416 } 417 418 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_KEYID)) { 419 struct flow_dissector_key_keyid *keyid; 420 421 keyid = skb_flow_dissector_target(flow_dissector, 422 FLOW_DISSECTOR_KEY_ENC_KEYID, 423 target_container); 424 keyid->keyid = tunnel_id_to_key32(key->tun_id); 425 } 426 427 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_PORTS)) { 428 struct flow_dissector_key_ports *tp; 429 430 tp = skb_flow_dissector_target(flow_dissector, 431 FLOW_DISSECTOR_KEY_ENC_PORTS, 432 target_container); 433 tp->src = key->tp_src; 434 tp->dst = key->tp_dst; 435 } 436 437 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_IP)) { 438 struct flow_dissector_key_ip *ip; 439 440 ip = skb_flow_dissector_target(flow_dissector, 441 FLOW_DISSECTOR_KEY_ENC_IP, 442 target_container); 443 ip->tos = key->tos; 444 ip->ttl = key->ttl; 445 } 446 447 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ENC_OPTS)) { 448 struct flow_dissector_key_enc_opts *enc_opt; 449 450 enc_opt = skb_flow_dissector_target(flow_dissector, 451 FLOW_DISSECTOR_KEY_ENC_OPTS, 452 target_container); 453 454 if (info->options_len) { 455 enc_opt->len = info->options_len; 456 ip_tunnel_info_opts_get(enc_opt->data, info); 457 enc_opt->dst_opt_type = info->key.tun_flags & 458 TUNNEL_OPTIONS_PRESENT; 459 } 460 } 461 } 462 EXPORT_SYMBOL(skb_flow_dissect_tunnel_info); 463 464 static enum flow_dissect_ret 465 __skb_flow_dissect_mpls(const struct sk_buff *skb, 466 struct flow_dissector *flow_dissector, 467 void *target_container, void *data, int nhoff, int hlen) 468 { 469 struct flow_dissector_key_keyid *key_keyid; 470 struct mpls_label *hdr, _hdr[2]; 471 u32 entry, label; 472 473 if (!dissector_uses_key(flow_dissector, 474 FLOW_DISSECTOR_KEY_MPLS_ENTROPY) && 475 !dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS)) 476 return FLOW_DISSECT_RET_OUT_GOOD; 477 478 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, 479 hlen, &_hdr); 480 if (!hdr) 481 return FLOW_DISSECT_RET_OUT_BAD; 482 483 entry = ntohl(hdr[0].entry); 484 label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT; 485 486 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_MPLS)) { 487 struct flow_dissector_key_mpls *key_mpls; 488 489 key_mpls = skb_flow_dissector_target(flow_dissector, 490 FLOW_DISSECTOR_KEY_MPLS, 491 target_container); 492 key_mpls->mpls_label = label; 493 key_mpls->mpls_ttl = (entry & MPLS_LS_TTL_MASK) 494 >> MPLS_LS_TTL_SHIFT; 495 key_mpls->mpls_tc = (entry & MPLS_LS_TC_MASK) 496 >> MPLS_LS_TC_SHIFT; 497 key_mpls->mpls_bos = (entry & MPLS_LS_S_MASK) 498 >> MPLS_LS_S_SHIFT; 499 } 500 501 if (label == MPLS_LABEL_ENTROPY) { 502 key_keyid = skb_flow_dissector_target(flow_dissector, 503 FLOW_DISSECTOR_KEY_MPLS_ENTROPY, 504 target_container); 505 key_keyid->keyid = hdr[1].entry & htonl(MPLS_LS_LABEL_MASK); 506 } 507 return FLOW_DISSECT_RET_OUT_GOOD; 508 } 509 510 static enum flow_dissect_ret 511 __skb_flow_dissect_arp(const struct sk_buff *skb, 512 struct flow_dissector *flow_dissector, 513 void *target_container, void *data, int nhoff, int hlen) 514 { 515 struct flow_dissector_key_arp *key_arp; 516 struct { 517 unsigned char ar_sha[ETH_ALEN]; 518 unsigned char ar_sip[4]; 519 unsigned char ar_tha[ETH_ALEN]; 520 unsigned char ar_tip[4]; 521 } *arp_eth, _arp_eth; 522 const struct arphdr *arp; 523 struct arphdr _arp; 524 525 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_ARP)) 526 return FLOW_DISSECT_RET_OUT_GOOD; 527 528 arp = __skb_header_pointer(skb, nhoff, sizeof(_arp), data, 529 hlen, &_arp); 530 if (!arp) 531 return FLOW_DISSECT_RET_OUT_BAD; 532 533 if (arp->ar_hrd != htons(ARPHRD_ETHER) || 534 arp->ar_pro != htons(ETH_P_IP) || 535 arp->ar_hln != ETH_ALEN || 536 arp->ar_pln != 4 || 537 (arp->ar_op != htons(ARPOP_REPLY) && 538 arp->ar_op != htons(ARPOP_REQUEST))) 539 return FLOW_DISSECT_RET_OUT_BAD; 540 541 arp_eth = __skb_header_pointer(skb, nhoff + sizeof(_arp), 542 sizeof(_arp_eth), data, 543 hlen, &_arp_eth); 544 if (!arp_eth) 545 return FLOW_DISSECT_RET_OUT_BAD; 546 547 key_arp = skb_flow_dissector_target(flow_dissector, 548 FLOW_DISSECTOR_KEY_ARP, 549 target_container); 550 551 memcpy(&key_arp->sip, arp_eth->ar_sip, sizeof(key_arp->sip)); 552 memcpy(&key_arp->tip, arp_eth->ar_tip, sizeof(key_arp->tip)); 553 554 /* Only store the lower byte of the opcode; 555 * this covers ARPOP_REPLY and ARPOP_REQUEST. 556 */ 557 key_arp->op = ntohs(arp->ar_op) & 0xff; 558 559 ether_addr_copy(key_arp->sha, arp_eth->ar_sha); 560 ether_addr_copy(key_arp->tha, arp_eth->ar_tha); 561 562 return FLOW_DISSECT_RET_OUT_GOOD; 563 } 564 565 static enum flow_dissect_ret 566 __skb_flow_dissect_gre(const struct sk_buff *skb, 567 struct flow_dissector_key_control *key_control, 568 struct flow_dissector *flow_dissector, 569 void *target_container, void *data, 570 __be16 *p_proto, int *p_nhoff, int *p_hlen, 571 unsigned int flags) 572 { 573 struct flow_dissector_key_keyid *key_keyid; 574 struct gre_base_hdr *hdr, _hdr; 575 int offset = 0; 576 u16 gre_ver; 577 578 hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), 579 data, *p_hlen, &_hdr); 580 if (!hdr) 581 return FLOW_DISSECT_RET_OUT_BAD; 582 583 /* Only look inside GRE without routing */ 584 if (hdr->flags & GRE_ROUTING) 585 return FLOW_DISSECT_RET_OUT_GOOD; 586 587 /* Only look inside GRE for version 0 and 1 */ 588 gre_ver = ntohs(hdr->flags & GRE_VERSION); 589 if (gre_ver > 1) 590 return FLOW_DISSECT_RET_OUT_GOOD; 591 592 *p_proto = hdr->protocol; 593 if (gre_ver) { 594 /* Version1 must be PPTP, and check the flags */ 595 if (!(*p_proto == GRE_PROTO_PPP && (hdr->flags & GRE_KEY))) 596 return FLOW_DISSECT_RET_OUT_GOOD; 597 } 598 599 offset += sizeof(struct gre_base_hdr); 600 601 if (hdr->flags & GRE_CSUM) 602 offset += sizeof_field(struct gre_full_hdr, csum) + 603 sizeof_field(struct gre_full_hdr, reserved1); 604 605 if (hdr->flags & GRE_KEY) { 606 const __be32 *keyid; 607 __be32 _keyid; 608 609 keyid = __skb_header_pointer(skb, *p_nhoff + offset, 610 sizeof(_keyid), 611 data, *p_hlen, &_keyid); 612 if (!keyid) 613 return FLOW_DISSECT_RET_OUT_BAD; 614 615 if (dissector_uses_key(flow_dissector, 616 FLOW_DISSECTOR_KEY_GRE_KEYID)) { 617 key_keyid = skb_flow_dissector_target(flow_dissector, 618 FLOW_DISSECTOR_KEY_GRE_KEYID, 619 target_container); 620 if (gre_ver == 0) 621 key_keyid->keyid = *keyid; 622 else 623 key_keyid->keyid = *keyid & GRE_PPTP_KEY_MASK; 624 } 625 offset += sizeof_field(struct gre_full_hdr, key); 626 } 627 628 if (hdr->flags & GRE_SEQ) 629 offset += sizeof_field(struct pptp_gre_header, seq); 630 631 if (gre_ver == 0) { 632 if (*p_proto == htons(ETH_P_TEB)) { 633 const struct ethhdr *eth; 634 struct ethhdr _eth; 635 636 eth = __skb_header_pointer(skb, *p_nhoff + offset, 637 sizeof(_eth), 638 data, *p_hlen, &_eth); 639 if (!eth) 640 return FLOW_DISSECT_RET_OUT_BAD; 641 *p_proto = eth->h_proto; 642 offset += sizeof(*eth); 643 644 /* Cap headers that we access via pointers at the 645 * end of the Ethernet header as our maximum alignment 646 * at that point is only 2 bytes. 647 */ 648 if (NET_IP_ALIGN) 649 *p_hlen = *p_nhoff + offset; 650 } 651 } else { /* version 1, must be PPTP */ 652 u8 _ppp_hdr[PPP_HDRLEN]; 653 u8 *ppp_hdr; 654 655 if (hdr->flags & GRE_ACK) 656 offset += sizeof_field(struct pptp_gre_header, ack); 657 658 ppp_hdr = __skb_header_pointer(skb, *p_nhoff + offset, 659 sizeof(_ppp_hdr), 660 data, *p_hlen, _ppp_hdr); 661 if (!ppp_hdr) 662 return FLOW_DISSECT_RET_OUT_BAD; 663 664 switch (PPP_PROTOCOL(ppp_hdr)) { 665 case PPP_IP: 666 *p_proto = htons(ETH_P_IP); 667 break; 668 case PPP_IPV6: 669 *p_proto = htons(ETH_P_IPV6); 670 break; 671 default: 672 /* Could probably catch some more like MPLS */ 673 break; 674 } 675 676 offset += PPP_HDRLEN; 677 } 678 679 *p_nhoff += offset; 680 key_control->flags |= FLOW_DIS_ENCAPSULATION; 681 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) 682 return FLOW_DISSECT_RET_OUT_GOOD; 683 684 return FLOW_DISSECT_RET_PROTO_AGAIN; 685 } 686 687 /** 688 * __skb_flow_dissect_batadv() - dissect batman-adv header 689 * @skb: sk_buff to with the batman-adv header 690 * @key_control: flow dissectors control key 691 * @data: raw buffer pointer to the packet, if NULL use skb->data 692 * @p_proto: pointer used to update the protocol to process next 693 * @p_nhoff: pointer used to update inner network header offset 694 * @hlen: packet header length 695 * @flags: any combination of FLOW_DISSECTOR_F_* 696 * 697 * ETH_P_BATMAN packets are tried to be dissected. Only 698 * &struct batadv_unicast packets are actually processed because they contain an 699 * inner ethernet header and are usually followed by actual network header. This 700 * allows the flow dissector to continue processing the packet. 701 * 702 * Return: FLOW_DISSECT_RET_PROTO_AGAIN when &struct batadv_unicast was found, 703 * FLOW_DISSECT_RET_OUT_GOOD when dissector should stop after encapsulation, 704 * otherwise FLOW_DISSECT_RET_OUT_BAD 705 */ 706 static enum flow_dissect_ret 707 __skb_flow_dissect_batadv(const struct sk_buff *skb, 708 struct flow_dissector_key_control *key_control, 709 void *data, __be16 *p_proto, int *p_nhoff, int hlen, 710 unsigned int flags) 711 { 712 struct { 713 struct batadv_unicast_packet batadv_unicast; 714 struct ethhdr eth; 715 } *hdr, _hdr; 716 717 hdr = __skb_header_pointer(skb, *p_nhoff, sizeof(_hdr), data, hlen, 718 &_hdr); 719 if (!hdr) 720 return FLOW_DISSECT_RET_OUT_BAD; 721 722 if (hdr->batadv_unicast.version != BATADV_COMPAT_VERSION) 723 return FLOW_DISSECT_RET_OUT_BAD; 724 725 if (hdr->batadv_unicast.packet_type != BATADV_UNICAST) 726 return FLOW_DISSECT_RET_OUT_BAD; 727 728 *p_proto = hdr->eth.h_proto; 729 *p_nhoff += sizeof(*hdr); 730 731 key_control->flags |= FLOW_DIS_ENCAPSULATION; 732 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) 733 return FLOW_DISSECT_RET_OUT_GOOD; 734 735 return FLOW_DISSECT_RET_PROTO_AGAIN; 736 } 737 738 static void 739 __skb_flow_dissect_tcp(const struct sk_buff *skb, 740 struct flow_dissector *flow_dissector, 741 void *target_container, void *data, int thoff, int hlen) 742 { 743 struct flow_dissector_key_tcp *key_tcp; 744 struct tcphdr *th, _th; 745 746 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_TCP)) 747 return; 748 749 th = __skb_header_pointer(skb, thoff, sizeof(_th), data, hlen, &_th); 750 if (!th) 751 return; 752 753 if (unlikely(__tcp_hdrlen(th) < sizeof(_th))) 754 return; 755 756 key_tcp = skb_flow_dissector_target(flow_dissector, 757 FLOW_DISSECTOR_KEY_TCP, 758 target_container); 759 key_tcp->flags = (*(__be16 *) &tcp_flag_word(th) & htons(0x0FFF)); 760 } 761 762 static void 763 __skb_flow_dissect_ports(const struct sk_buff *skb, 764 struct flow_dissector *flow_dissector, 765 void *target_container, void *data, int nhoff, 766 u8 ip_proto, int hlen) 767 { 768 enum flow_dissector_key_id dissector_ports = FLOW_DISSECTOR_KEY_MAX; 769 struct flow_dissector_key_ports *key_ports; 770 771 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS)) 772 dissector_ports = FLOW_DISSECTOR_KEY_PORTS; 773 else if (dissector_uses_key(flow_dissector, 774 FLOW_DISSECTOR_KEY_PORTS_RANGE)) 775 dissector_ports = FLOW_DISSECTOR_KEY_PORTS_RANGE; 776 777 if (dissector_ports == FLOW_DISSECTOR_KEY_MAX) 778 return; 779 780 key_ports = skb_flow_dissector_target(flow_dissector, 781 dissector_ports, 782 target_container); 783 key_ports->ports = __skb_flow_get_ports(skb, nhoff, ip_proto, 784 data, hlen); 785 } 786 787 static void 788 __skb_flow_dissect_ipv4(const struct sk_buff *skb, 789 struct flow_dissector *flow_dissector, 790 void *target_container, void *data, const struct iphdr *iph) 791 { 792 struct flow_dissector_key_ip *key_ip; 793 794 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP)) 795 return; 796 797 key_ip = skb_flow_dissector_target(flow_dissector, 798 FLOW_DISSECTOR_KEY_IP, 799 target_container); 800 key_ip->tos = iph->tos; 801 key_ip->ttl = iph->ttl; 802 } 803 804 static void 805 __skb_flow_dissect_ipv6(const struct sk_buff *skb, 806 struct flow_dissector *flow_dissector, 807 void *target_container, void *data, const struct ipv6hdr *iph) 808 { 809 struct flow_dissector_key_ip *key_ip; 810 811 if (!dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IP)) 812 return; 813 814 key_ip = skb_flow_dissector_target(flow_dissector, 815 FLOW_DISSECTOR_KEY_IP, 816 target_container); 817 key_ip->tos = ipv6_get_dsfield(iph); 818 key_ip->ttl = iph->hop_limit; 819 } 820 821 /* Maximum number of protocol headers that can be parsed in 822 * __skb_flow_dissect 823 */ 824 #define MAX_FLOW_DISSECT_HDRS 15 825 826 static bool skb_flow_dissect_allowed(int *num_hdrs) 827 { 828 ++*num_hdrs; 829 830 return (*num_hdrs <= MAX_FLOW_DISSECT_HDRS); 831 } 832 833 static void __skb_flow_bpf_to_target(const struct bpf_flow_keys *flow_keys, 834 struct flow_dissector *flow_dissector, 835 void *target_container) 836 { 837 struct flow_dissector_key_ports *key_ports = NULL; 838 struct flow_dissector_key_control *key_control; 839 struct flow_dissector_key_basic *key_basic; 840 struct flow_dissector_key_addrs *key_addrs; 841 struct flow_dissector_key_tags *key_tags; 842 843 key_control = skb_flow_dissector_target(flow_dissector, 844 FLOW_DISSECTOR_KEY_CONTROL, 845 target_container); 846 key_control->thoff = flow_keys->thoff; 847 if (flow_keys->is_frag) 848 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 849 if (flow_keys->is_first_frag) 850 key_control->flags |= FLOW_DIS_FIRST_FRAG; 851 if (flow_keys->is_encap) 852 key_control->flags |= FLOW_DIS_ENCAPSULATION; 853 854 key_basic = skb_flow_dissector_target(flow_dissector, 855 FLOW_DISSECTOR_KEY_BASIC, 856 target_container); 857 key_basic->n_proto = flow_keys->n_proto; 858 key_basic->ip_proto = flow_keys->ip_proto; 859 860 if (flow_keys->addr_proto == ETH_P_IP && 861 dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_IPV4_ADDRS)) { 862 key_addrs = skb_flow_dissector_target(flow_dissector, 863 FLOW_DISSECTOR_KEY_IPV4_ADDRS, 864 target_container); 865 key_addrs->v4addrs.src = flow_keys->ipv4_src; 866 key_addrs->v4addrs.dst = flow_keys->ipv4_dst; 867 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS; 868 } else if (flow_keys->addr_proto == ETH_P_IPV6 && 869 dissector_uses_key(flow_dissector, 870 FLOW_DISSECTOR_KEY_IPV6_ADDRS)) { 871 key_addrs = skb_flow_dissector_target(flow_dissector, 872 FLOW_DISSECTOR_KEY_IPV6_ADDRS, 873 target_container); 874 memcpy(&key_addrs->v6addrs, &flow_keys->ipv6_src, 875 sizeof(key_addrs->v6addrs)); 876 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 877 } 878 879 if (dissector_uses_key(flow_dissector, FLOW_DISSECTOR_KEY_PORTS)) 880 key_ports = skb_flow_dissector_target(flow_dissector, 881 FLOW_DISSECTOR_KEY_PORTS, 882 target_container); 883 else if (dissector_uses_key(flow_dissector, 884 FLOW_DISSECTOR_KEY_PORTS_RANGE)) 885 key_ports = skb_flow_dissector_target(flow_dissector, 886 FLOW_DISSECTOR_KEY_PORTS_RANGE, 887 target_container); 888 889 if (key_ports) { 890 key_ports->src = flow_keys->sport; 891 key_ports->dst = flow_keys->dport; 892 } 893 894 if (dissector_uses_key(flow_dissector, 895 FLOW_DISSECTOR_KEY_FLOW_LABEL)) { 896 key_tags = skb_flow_dissector_target(flow_dissector, 897 FLOW_DISSECTOR_KEY_FLOW_LABEL, 898 target_container); 899 key_tags->flow_label = ntohl(flow_keys->flow_label); 900 } 901 } 902 903 bool bpf_flow_dissect(struct bpf_prog *prog, struct bpf_flow_dissector *ctx, 904 __be16 proto, int nhoff, int hlen, unsigned int flags) 905 { 906 struct bpf_flow_keys *flow_keys = ctx->flow_keys; 907 u32 result; 908 909 /* Pass parameters to the BPF program */ 910 memset(flow_keys, 0, sizeof(*flow_keys)); 911 flow_keys->n_proto = proto; 912 flow_keys->nhoff = nhoff; 913 flow_keys->thoff = flow_keys->nhoff; 914 915 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG != 916 (int)FLOW_DISSECTOR_F_PARSE_1ST_FRAG); 917 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL != 918 (int)FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 919 BUILD_BUG_ON((int)BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP != 920 (int)FLOW_DISSECTOR_F_STOP_AT_ENCAP); 921 flow_keys->flags = flags; 922 923 preempt_disable(); 924 result = BPF_PROG_RUN(prog, ctx); 925 preempt_enable(); 926 927 flow_keys->nhoff = clamp_t(u16, flow_keys->nhoff, nhoff, hlen); 928 flow_keys->thoff = clamp_t(u16, flow_keys->thoff, 929 flow_keys->nhoff, hlen); 930 931 return result == BPF_OK; 932 } 933 934 /** 935 * __skb_flow_dissect - extract the flow_keys struct and return it 936 * @net: associated network namespace, derived from @skb if NULL 937 * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified 938 * @flow_dissector: list of keys to dissect 939 * @target_container: target structure to put dissected values into 940 * @data: raw buffer pointer to the packet, if NULL use skb->data 941 * @proto: protocol for which to get the flow, if @data is NULL use skb->protocol 942 * @nhoff: network header offset, if @data is NULL use skb_network_offset(skb) 943 * @hlen: packet header length, if @data is NULL use skb_headlen(skb) 944 * @flags: flags that control the dissection process, e.g. 945 * FLOW_DISSECTOR_F_STOP_AT_ENCAP. 946 * 947 * The function will try to retrieve individual keys into target specified 948 * by flow_dissector from either the skbuff or a raw buffer specified by the 949 * rest parameters. 950 * 951 * Caller must take care of zeroing target container memory. 952 */ 953 bool __skb_flow_dissect(const struct net *net, 954 const struct sk_buff *skb, 955 struct flow_dissector *flow_dissector, 956 void *target_container, 957 void *data, __be16 proto, int nhoff, int hlen, 958 unsigned int flags) 959 { 960 struct flow_dissector_key_control *key_control; 961 struct flow_dissector_key_basic *key_basic; 962 struct flow_dissector_key_addrs *key_addrs; 963 struct flow_dissector_key_tags *key_tags; 964 struct flow_dissector_key_vlan *key_vlan; 965 struct bpf_prog *attached = NULL; 966 enum flow_dissect_ret fdret; 967 enum flow_dissector_key_id dissector_vlan = FLOW_DISSECTOR_KEY_MAX; 968 int num_hdrs = 0; 969 u8 ip_proto = 0; 970 bool ret; 971 972 if (!data) { 973 data = skb->data; 974 proto = skb_vlan_tag_present(skb) ? 975 skb->vlan_proto : skb->protocol; 976 nhoff = skb_network_offset(skb); 977 hlen = skb_headlen(skb); 978 #if IS_ENABLED(CONFIG_NET_DSA) 979 if (unlikely(skb->dev && netdev_uses_dsa(skb->dev) && 980 proto == htons(ETH_P_XDSA))) { 981 const struct dsa_device_ops *ops; 982 int offset = 0; 983 984 ops = skb->dev->dsa_ptr->tag_ops; 985 if (ops->flow_dissect && 986 !ops->flow_dissect(skb, &proto, &offset)) { 987 hlen -= offset; 988 nhoff += offset; 989 } 990 } 991 #endif 992 } 993 994 /* It is ensured by skb_flow_dissector_init() that control key will 995 * be always present. 996 */ 997 key_control = skb_flow_dissector_target(flow_dissector, 998 FLOW_DISSECTOR_KEY_CONTROL, 999 target_container); 1000 1001 /* It is ensured by skb_flow_dissector_init() that basic key will 1002 * be always present. 1003 */ 1004 key_basic = skb_flow_dissector_target(flow_dissector, 1005 FLOW_DISSECTOR_KEY_BASIC, 1006 target_container); 1007 1008 if (skb) { 1009 if (!net) { 1010 if (skb->dev) 1011 net = dev_net(skb->dev); 1012 else if (skb->sk) 1013 net = sock_net(skb->sk); 1014 } 1015 } 1016 1017 WARN_ON_ONCE(!net); 1018 if (net) { 1019 rcu_read_lock(); 1020 attached = rcu_dereference(init_net.flow_dissector_prog); 1021 1022 if (!attached) 1023 attached = rcu_dereference(net->flow_dissector_prog); 1024 1025 if (attached) { 1026 struct bpf_flow_keys flow_keys; 1027 struct bpf_flow_dissector ctx = { 1028 .flow_keys = &flow_keys, 1029 .data = data, 1030 .data_end = data + hlen, 1031 }; 1032 __be16 n_proto = proto; 1033 1034 if (skb) { 1035 ctx.skb = skb; 1036 /* we can't use 'proto' in the skb case 1037 * because it might be set to skb->vlan_proto 1038 * which has been pulled from the data 1039 */ 1040 n_proto = skb->protocol; 1041 } 1042 1043 ret = bpf_flow_dissect(attached, &ctx, n_proto, nhoff, 1044 hlen, flags); 1045 __skb_flow_bpf_to_target(&flow_keys, flow_dissector, 1046 target_container); 1047 rcu_read_unlock(); 1048 return ret; 1049 } 1050 rcu_read_unlock(); 1051 } 1052 1053 if (dissector_uses_key(flow_dissector, 1054 FLOW_DISSECTOR_KEY_ETH_ADDRS)) { 1055 struct ethhdr *eth = eth_hdr(skb); 1056 struct flow_dissector_key_eth_addrs *key_eth_addrs; 1057 1058 key_eth_addrs = skb_flow_dissector_target(flow_dissector, 1059 FLOW_DISSECTOR_KEY_ETH_ADDRS, 1060 target_container); 1061 memcpy(key_eth_addrs, ð->h_dest, sizeof(*key_eth_addrs)); 1062 } 1063 1064 proto_again: 1065 fdret = FLOW_DISSECT_RET_CONTINUE; 1066 1067 switch (proto) { 1068 case htons(ETH_P_IP): { 1069 const struct iphdr *iph; 1070 struct iphdr _iph; 1071 1072 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); 1073 if (!iph || iph->ihl < 5) { 1074 fdret = FLOW_DISSECT_RET_OUT_BAD; 1075 break; 1076 } 1077 1078 nhoff += iph->ihl * 4; 1079 1080 ip_proto = iph->protocol; 1081 1082 if (dissector_uses_key(flow_dissector, 1083 FLOW_DISSECTOR_KEY_IPV4_ADDRS)) { 1084 key_addrs = skb_flow_dissector_target(flow_dissector, 1085 FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1086 target_container); 1087 1088 memcpy(&key_addrs->v4addrs, &iph->saddr, 1089 sizeof(key_addrs->v4addrs)); 1090 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS; 1091 } 1092 1093 if (ip_is_fragment(iph)) { 1094 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 1095 1096 if (iph->frag_off & htons(IP_OFFSET)) { 1097 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1098 break; 1099 } else { 1100 key_control->flags |= FLOW_DIS_FIRST_FRAG; 1101 if (!(flags & 1102 FLOW_DISSECTOR_F_PARSE_1ST_FRAG)) { 1103 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1104 break; 1105 } 1106 } 1107 } 1108 1109 __skb_flow_dissect_ipv4(skb, flow_dissector, 1110 target_container, data, iph); 1111 1112 break; 1113 } 1114 case htons(ETH_P_IPV6): { 1115 const struct ipv6hdr *iph; 1116 struct ipv6hdr _iph; 1117 1118 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); 1119 if (!iph) { 1120 fdret = FLOW_DISSECT_RET_OUT_BAD; 1121 break; 1122 } 1123 1124 ip_proto = iph->nexthdr; 1125 nhoff += sizeof(struct ipv6hdr); 1126 1127 if (dissector_uses_key(flow_dissector, 1128 FLOW_DISSECTOR_KEY_IPV6_ADDRS)) { 1129 key_addrs = skb_flow_dissector_target(flow_dissector, 1130 FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1131 target_container); 1132 1133 memcpy(&key_addrs->v6addrs, &iph->saddr, 1134 sizeof(key_addrs->v6addrs)); 1135 key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 1136 } 1137 1138 if ((dissector_uses_key(flow_dissector, 1139 FLOW_DISSECTOR_KEY_FLOW_LABEL) || 1140 (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)) && 1141 ip6_flowlabel(iph)) { 1142 __be32 flow_label = ip6_flowlabel(iph); 1143 1144 if (dissector_uses_key(flow_dissector, 1145 FLOW_DISSECTOR_KEY_FLOW_LABEL)) { 1146 key_tags = skb_flow_dissector_target(flow_dissector, 1147 FLOW_DISSECTOR_KEY_FLOW_LABEL, 1148 target_container); 1149 key_tags->flow_label = ntohl(flow_label); 1150 } 1151 if (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL) { 1152 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1153 break; 1154 } 1155 } 1156 1157 __skb_flow_dissect_ipv6(skb, flow_dissector, 1158 target_container, data, iph); 1159 1160 break; 1161 } 1162 case htons(ETH_P_8021AD): 1163 case htons(ETH_P_8021Q): { 1164 const struct vlan_hdr *vlan = NULL; 1165 struct vlan_hdr _vlan; 1166 __be16 saved_vlan_tpid = proto; 1167 1168 if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX && 1169 skb && skb_vlan_tag_present(skb)) { 1170 proto = skb->protocol; 1171 } else { 1172 vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan), 1173 data, hlen, &_vlan); 1174 if (!vlan) { 1175 fdret = FLOW_DISSECT_RET_OUT_BAD; 1176 break; 1177 } 1178 1179 proto = vlan->h_vlan_encapsulated_proto; 1180 nhoff += sizeof(*vlan); 1181 } 1182 1183 if (dissector_vlan == FLOW_DISSECTOR_KEY_MAX) { 1184 dissector_vlan = FLOW_DISSECTOR_KEY_VLAN; 1185 } else if (dissector_vlan == FLOW_DISSECTOR_KEY_VLAN) { 1186 dissector_vlan = FLOW_DISSECTOR_KEY_CVLAN; 1187 } else { 1188 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1189 break; 1190 } 1191 1192 if (dissector_uses_key(flow_dissector, dissector_vlan)) { 1193 key_vlan = skb_flow_dissector_target(flow_dissector, 1194 dissector_vlan, 1195 target_container); 1196 1197 if (!vlan) { 1198 key_vlan->vlan_id = skb_vlan_tag_get_id(skb); 1199 key_vlan->vlan_priority = skb_vlan_tag_get_prio(skb); 1200 } else { 1201 key_vlan->vlan_id = ntohs(vlan->h_vlan_TCI) & 1202 VLAN_VID_MASK; 1203 key_vlan->vlan_priority = 1204 (ntohs(vlan->h_vlan_TCI) & 1205 VLAN_PRIO_MASK) >> VLAN_PRIO_SHIFT; 1206 } 1207 key_vlan->vlan_tpid = saved_vlan_tpid; 1208 } 1209 1210 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1211 break; 1212 } 1213 case htons(ETH_P_PPP_SES): { 1214 struct { 1215 struct pppoe_hdr hdr; 1216 __be16 proto; 1217 } *hdr, _hdr; 1218 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr); 1219 if (!hdr) { 1220 fdret = FLOW_DISSECT_RET_OUT_BAD; 1221 break; 1222 } 1223 1224 proto = hdr->proto; 1225 nhoff += PPPOE_SES_HLEN; 1226 switch (proto) { 1227 case htons(PPP_IP): 1228 proto = htons(ETH_P_IP); 1229 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1230 break; 1231 case htons(PPP_IPV6): 1232 proto = htons(ETH_P_IPV6); 1233 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1234 break; 1235 default: 1236 fdret = FLOW_DISSECT_RET_OUT_BAD; 1237 break; 1238 } 1239 break; 1240 } 1241 case htons(ETH_P_TIPC): { 1242 struct tipc_basic_hdr *hdr, _hdr; 1243 1244 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), 1245 data, hlen, &_hdr); 1246 if (!hdr) { 1247 fdret = FLOW_DISSECT_RET_OUT_BAD; 1248 break; 1249 } 1250 1251 if (dissector_uses_key(flow_dissector, 1252 FLOW_DISSECTOR_KEY_TIPC)) { 1253 key_addrs = skb_flow_dissector_target(flow_dissector, 1254 FLOW_DISSECTOR_KEY_TIPC, 1255 target_container); 1256 key_addrs->tipckey.key = tipc_hdr_rps_key(hdr); 1257 key_control->addr_type = FLOW_DISSECTOR_KEY_TIPC; 1258 } 1259 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1260 break; 1261 } 1262 1263 case htons(ETH_P_MPLS_UC): 1264 case htons(ETH_P_MPLS_MC): 1265 fdret = __skb_flow_dissect_mpls(skb, flow_dissector, 1266 target_container, data, 1267 nhoff, hlen); 1268 break; 1269 case htons(ETH_P_FCOE): 1270 if ((hlen - nhoff) < FCOE_HEADER_LEN) { 1271 fdret = FLOW_DISSECT_RET_OUT_BAD; 1272 break; 1273 } 1274 1275 nhoff += FCOE_HEADER_LEN; 1276 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1277 break; 1278 1279 case htons(ETH_P_ARP): 1280 case htons(ETH_P_RARP): 1281 fdret = __skb_flow_dissect_arp(skb, flow_dissector, 1282 target_container, data, 1283 nhoff, hlen); 1284 break; 1285 1286 case htons(ETH_P_BATMAN): 1287 fdret = __skb_flow_dissect_batadv(skb, key_control, data, 1288 &proto, &nhoff, hlen, flags); 1289 break; 1290 1291 default: 1292 fdret = FLOW_DISSECT_RET_OUT_BAD; 1293 break; 1294 } 1295 1296 /* Process result of proto processing */ 1297 switch (fdret) { 1298 case FLOW_DISSECT_RET_OUT_GOOD: 1299 goto out_good; 1300 case FLOW_DISSECT_RET_PROTO_AGAIN: 1301 if (skb_flow_dissect_allowed(&num_hdrs)) 1302 goto proto_again; 1303 goto out_good; 1304 case FLOW_DISSECT_RET_CONTINUE: 1305 case FLOW_DISSECT_RET_IPPROTO_AGAIN: 1306 break; 1307 case FLOW_DISSECT_RET_OUT_BAD: 1308 default: 1309 goto out_bad; 1310 } 1311 1312 ip_proto_again: 1313 fdret = FLOW_DISSECT_RET_CONTINUE; 1314 1315 switch (ip_proto) { 1316 case IPPROTO_GRE: 1317 fdret = __skb_flow_dissect_gre(skb, key_control, flow_dissector, 1318 target_container, data, 1319 &proto, &nhoff, &hlen, flags); 1320 break; 1321 1322 case NEXTHDR_HOP: 1323 case NEXTHDR_ROUTING: 1324 case NEXTHDR_DEST: { 1325 u8 _opthdr[2], *opthdr; 1326 1327 if (proto != htons(ETH_P_IPV6)) 1328 break; 1329 1330 opthdr = __skb_header_pointer(skb, nhoff, sizeof(_opthdr), 1331 data, hlen, &_opthdr); 1332 if (!opthdr) { 1333 fdret = FLOW_DISSECT_RET_OUT_BAD; 1334 break; 1335 } 1336 1337 ip_proto = opthdr[0]; 1338 nhoff += (opthdr[1] + 1) << 3; 1339 1340 fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN; 1341 break; 1342 } 1343 case NEXTHDR_FRAGMENT: { 1344 struct frag_hdr _fh, *fh; 1345 1346 if (proto != htons(ETH_P_IPV6)) 1347 break; 1348 1349 fh = __skb_header_pointer(skb, nhoff, sizeof(_fh), 1350 data, hlen, &_fh); 1351 1352 if (!fh) { 1353 fdret = FLOW_DISSECT_RET_OUT_BAD; 1354 break; 1355 } 1356 1357 key_control->flags |= FLOW_DIS_IS_FRAGMENT; 1358 1359 nhoff += sizeof(_fh); 1360 ip_proto = fh->nexthdr; 1361 1362 if (!(fh->frag_off & htons(IP6_OFFSET))) { 1363 key_control->flags |= FLOW_DIS_FIRST_FRAG; 1364 if (flags & FLOW_DISSECTOR_F_PARSE_1ST_FRAG) { 1365 fdret = FLOW_DISSECT_RET_IPPROTO_AGAIN; 1366 break; 1367 } 1368 } 1369 1370 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1371 break; 1372 } 1373 case IPPROTO_IPIP: 1374 proto = htons(ETH_P_IP); 1375 1376 key_control->flags |= FLOW_DIS_ENCAPSULATION; 1377 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) { 1378 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1379 break; 1380 } 1381 1382 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1383 break; 1384 1385 case IPPROTO_IPV6: 1386 proto = htons(ETH_P_IPV6); 1387 1388 key_control->flags |= FLOW_DIS_ENCAPSULATION; 1389 if (flags & FLOW_DISSECTOR_F_STOP_AT_ENCAP) { 1390 fdret = FLOW_DISSECT_RET_OUT_GOOD; 1391 break; 1392 } 1393 1394 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1395 break; 1396 1397 1398 case IPPROTO_MPLS: 1399 proto = htons(ETH_P_MPLS_UC); 1400 fdret = FLOW_DISSECT_RET_PROTO_AGAIN; 1401 break; 1402 1403 case IPPROTO_TCP: 1404 __skb_flow_dissect_tcp(skb, flow_dissector, target_container, 1405 data, nhoff, hlen); 1406 break; 1407 1408 case IPPROTO_ICMP: 1409 case IPPROTO_ICMPV6: 1410 __skb_flow_dissect_icmp(skb, flow_dissector, target_container, 1411 data, nhoff, hlen); 1412 break; 1413 1414 default: 1415 break; 1416 } 1417 1418 if (!(key_control->flags & FLOW_DIS_IS_FRAGMENT)) 1419 __skb_flow_dissect_ports(skb, flow_dissector, target_container, 1420 data, nhoff, ip_proto, hlen); 1421 1422 /* Process result of IP proto processing */ 1423 switch (fdret) { 1424 case FLOW_DISSECT_RET_PROTO_AGAIN: 1425 if (skb_flow_dissect_allowed(&num_hdrs)) 1426 goto proto_again; 1427 break; 1428 case FLOW_DISSECT_RET_IPPROTO_AGAIN: 1429 if (skb_flow_dissect_allowed(&num_hdrs)) 1430 goto ip_proto_again; 1431 break; 1432 case FLOW_DISSECT_RET_OUT_GOOD: 1433 case FLOW_DISSECT_RET_CONTINUE: 1434 break; 1435 case FLOW_DISSECT_RET_OUT_BAD: 1436 default: 1437 goto out_bad; 1438 } 1439 1440 out_good: 1441 ret = true; 1442 1443 out: 1444 key_control->thoff = min_t(u16, nhoff, skb ? skb->len : hlen); 1445 key_basic->n_proto = proto; 1446 key_basic->ip_proto = ip_proto; 1447 1448 return ret; 1449 1450 out_bad: 1451 ret = false; 1452 goto out; 1453 } 1454 EXPORT_SYMBOL(__skb_flow_dissect); 1455 1456 static siphash_key_t hashrnd __read_mostly; 1457 static __always_inline void __flow_hash_secret_init(void) 1458 { 1459 net_get_random_once(&hashrnd, sizeof(hashrnd)); 1460 } 1461 1462 static const void *flow_keys_hash_start(const struct flow_keys *flow) 1463 { 1464 BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % SIPHASH_ALIGNMENT); 1465 return &flow->FLOW_KEYS_HASH_START_FIELD; 1466 } 1467 1468 static inline size_t flow_keys_hash_length(const struct flow_keys *flow) 1469 { 1470 size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs); 1471 1472 BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32)); 1473 1474 switch (flow->control.addr_type) { 1475 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1476 diff -= sizeof(flow->addrs.v4addrs); 1477 break; 1478 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1479 diff -= sizeof(flow->addrs.v6addrs); 1480 break; 1481 case FLOW_DISSECTOR_KEY_TIPC: 1482 diff -= sizeof(flow->addrs.tipckey); 1483 break; 1484 } 1485 return sizeof(*flow) - diff; 1486 } 1487 1488 __be32 flow_get_u32_src(const struct flow_keys *flow) 1489 { 1490 switch (flow->control.addr_type) { 1491 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1492 return flow->addrs.v4addrs.src; 1493 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1494 return (__force __be32)ipv6_addr_hash( 1495 &flow->addrs.v6addrs.src); 1496 case FLOW_DISSECTOR_KEY_TIPC: 1497 return flow->addrs.tipckey.key; 1498 default: 1499 return 0; 1500 } 1501 } 1502 EXPORT_SYMBOL(flow_get_u32_src); 1503 1504 __be32 flow_get_u32_dst(const struct flow_keys *flow) 1505 { 1506 switch (flow->control.addr_type) { 1507 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1508 return flow->addrs.v4addrs.dst; 1509 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1510 return (__force __be32)ipv6_addr_hash( 1511 &flow->addrs.v6addrs.dst); 1512 default: 1513 return 0; 1514 } 1515 } 1516 EXPORT_SYMBOL(flow_get_u32_dst); 1517 1518 /* Sort the source and destination IP (and the ports if the IP are the same), 1519 * to have consistent hash within the two directions 1520 */ 1521 static inline void __flow_hash_consistentify(struct flow_keys *keys) 1522 { 1523 int addr_diff, i; 1524 1525 switch (keys->control.addr_type) { 1526 case FLOW_DISSECTOR_KEY_IPV4_ADDRS: 1527 addr_diff = (__force u32)keys->addrs.v4addrs.dst - 1528 (__force u32)keys->addrs.v4addrs.src; 1529 if ((addr_diff < 0) || 1530 (addr_diff == 0 && 1531 ((__force u16)keys->ports.dst < 1532 (__force u16)keys->ports.src))) { 1533 swap(keys->addrs.v4addrs.src, keys->addrs.v4addrs.dst); 1534 swap(keys->ports.src, keys->ports.dst); 1535 } 1536 break; 1537 case FLOW_DISSECTOR_KEY_IPV6_ADDRS: 1538 addr_diff = memcmp(&keys->addrs.v6addrs.dst, 1539 &keys->addrs.v6addrs.src, 1540 sizeof(keys->addrs.v6addrs.dst)); 1541 if ((addr_diff < 0) || 1542 (addr_diff == 0 && 1543 ((__force u16)keys->ports.dst < 1544 (__force u16)keys->ports.src))) { 1545 for (i = 0; i < 4; i++) 1546 swap(keys->addrs.v6addrs.src.s6_addr32[i], 1547 keys->addrs.v6addrs.dst.s6_addr32[i]); 1548 swap(keys->ports.src, keys->ports.dst); 1549 } 1550 break; 1551 } 1552 } 1553 1554 static inline u32 __flow_hash_from_keys(struct flow_keys *keys, 1555 const siphash_key_t *keyval) 1556 { 1557 u32 hash; 1558 1559 __flow_hash_consistentify(keys); 1560 1561 hash = siphash(flow_keys_hash_start(keys), 1562 flow_keys_hash_length(keys), keyval); 1563 if (!hash) 1564 hash = 1; 1565 1566 return hash; 1567 } 1568 1569 u32 flow_hash_from_keys(struct flow_keys *keys) 1570 { 1571 __flow_hash_secret_init(); 1572 return __flow_hash_from_keys(keys, &hashrnd); 1573 } 1574 EXPORT_SYMBOL(flow_hash_from_keys); 1575 1576 static inline u32 ___skb_get_hash(const struct sk_buff *skb, 1577 struct flow_keys *keys, 1578 const siphash_key_t *keyval) 1579 { 1580 skb_flow_dissect_flow_keys(skb, keys, 1581 FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 1582 1583 return __flow_hash_from_keys(keys, keyval); 1584 } 1585 1586 struct _flow_keys_digest_data { 1587 __be16 n_proto; 1588 u8 ip_proto; 1589 u8 padding; 1590 __be32 ports; 1591 __be32 src; 1592 __be32 dst; 1593 }; 1594 1595 void make_flow_keys_digest(struct flow_keys_digest *digest, 1596 const struct flow_keys *flow) 1597 { 1598 struct _flow_keys_digest_data *data = 1599 (struct _flow_keys_digest_data *)digest; 1600 1601 BUILD_BUG_ON(sizeof(*data) > sizeof(*digest)); 1602 1603 memset(digest, 0, sizeof(*digest)); 1604 1605 data->n_proto = flow->basic.n_proto; 1606 data->ip_proto = flow->basic.ip_proto; 1607 data->ports = flow->ports.ports; 1608 data->src = flow->addrs.v4addrs.src; 1609 data->dst = flow->addrs.v4addrs.dst; 1610 } 1611 EXPORT_SYMBOL(make_flow_keys_digest); 1612 1613 static struct flow_dissector flow_keys_dissector_symmetric __read_mostly; 1614 1615 u32 __skb_get_hash_symmetric(const struct sk_buff *skb) 1616 { 1617 struct flow_keys keys; 1618 1619 __flow_hash_secret_init(); 1620 1621 memset(&keys, 0, sizeof(keys)); 1622 __skb_flow_dissect(NULL, skb, &flow_keys_dissector_symmetric, 1623 &keys, NULL, 0, 0, 0, 1624 FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); 1625 1626 return __flow_hash_from_keys(&keys, &hashrnd); 1627 } 1628 EXPORT_SYMBOL_GPL(__skb_get_hash_symmetric); 1629 1630 /** 1631 * __skb_get_hash: calculate a flow hash 1632 * @skb: sk_buff to calculate flow hash from 1633 * 1634 * This function calculates a flow hash based on src/dst addresses 1635 * and src/dst port numbers. Sets hash in skb to non-zero hash value 1636 * on success, zero indicates no valid hash. Also, sets l4_hash in skb 1637 * if hash is a canonical 4-tuple hash over transport ports. 1638 */ 1639 void __skb_get_hash(struct sk_buff *skb) 1640 { 1641 struct flow_keys keys; 1642 u32 hash; 1643 1644 __flow_hash_secret_init(); 1645 1646 hash = ___skb_get_hash(skb, &keys, &hashrnd); 1647 1648 __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys)); 1649 } 1650 EXPORT_SYMBOL(__skb_get_hash); 1651 1652 __u32 skb_get_hash_perturb(const struct sk_buff *skb, 1653 const siphash_key_t *perturb) 1654 { 1655 struct flow_keys keys; 1656 1657 return ___skb_get_hash(skb, &keys, perturb); 1658 } 1659 EXPORT_SYMBOL(skb_get_hash_perturb); 1660 1661 u32 __skb_get_poff(const struct sk_buff *skb, void *data, 1662 const struct flow_keys_basic *keys, int hlen) 1663 { 1664 u32 poff = keys->control.thoff; 1665 1666 /* skip L4 headers for fragments after the first */ 1667 if ((keys->control.flags & FLOW_DIS_IS_FRAGMENT) && 1668 !(keys->control.flags & FLOW_DIS_FIRST_FRAG)) 1669 return poff; 1670 1671 switch (keys->basic.ip_proto) { 1672 case IPPROTO_TCP: { 1673 /* access doff as u8 to avoid unaligned access */ 1674 const u8 *doff; 1675 u8 _doff; 1676 1677 doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff), 1678 data, hlen, &_doff); 1679 if (!doff) 1680 return poff; 1681 1682 poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2); 1683 break; 1684 } 1685 case IPPROTO_UDP: 1686 case IPPROTO_UDPLITE: 1687 poff += sizeof(struct udphdr); 1688 break; 1689 /* For the rest, we do not really care about header 1690 * extensions at this point for now. 1691 */ 1692 case IPPROTO_ICMP: 1693 poff += sizeof(struct icmphdr); 1694 break; 1695 case IPPROTO_ICMPV6: 1696 poff += sizeof(struct icmp6hdr); 1697 break; 1698 case IPPROTO_IGMP: 1699 poff += sizeof(struct igmphdr); 1700 break; 1701 case IPPROTO_DCCP: 1702 poff += sizeof(struct dccp_hdr); 1703 break; 1704 case IPPROTO_SCTP: 1705 poff += sizeof(struct sctphdr); 1706 break; 1707 } 1708 1709 return poff; 1710 } 1711 1712 /** 1713 * skb_get_poff - get the offset to the payload 1714 * @skb: sk_buff to get the payload offset from 1715 * 1716 * The function will get the offset to the payload as far as it could 1717 * be dissected. The main user is currently BPF, so that we can dynamically 1718 * truncate packets without needing to push actual payload to the user 1719 * space and can analyze headers only, instead. 1720 */ 1721 u32 skb_get_poff(const struct sk_buff *skb) 1722 { 1723 struct flow_keys_basic keys; 1724 1725 if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys, 1726 NULL, 0, 0, 0, 0)) 1727 return 0; 1728 1729 return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb)); 1730 } 1731 1732 __u32 __get_hash_from_flowi6(const struct flowi6 *fl6, struct flow_keys *keys) 1733 { 1734 memset(keys, 0, sizeof(*keys)); 1735 1736 memcpy(&keys->addrs.v6addrs.src, &fl6->saddr, 1737 sizeof(keys->addrs.v6addrs.src)); 1738 memcpy(&keys->addrs.v6addrs.dst, &fl6->daddr, 1739 sizeof(keys->addrs.v6addrs.dst)); 1740 keys->control.addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; 1741 keys->ports.src = fl6->fl6_sport; 1742 keys->ports.dst = fl6->fl6_dport; 1743 keys->keyid.keyid = fl6->fl6_gre_key; 1744 keys->tags.flow_label = (__force u32)flowi6_get_flowlabel(fl6); 1745 keys->basic.ip_proto = fl6->flowi6_proto; 1746 1747 return flow_hash_from_keys(keys); 1748 } 1749 EXPORT_SYMBOL(__get_hash_from_flowi6); 1750 1751 static const struct flow_dissector_key flow_keys_dissector_keys[] = { 1752 { 1753 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1754 .offset = offsetof(struct flow_keys, control), 1755 }, 1756 { 1757 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1758 .offset = offsetof(struct flow_keys, basic), 1759 }, 1760 { 1761 .key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1762 .offset = offsetof(struct flow_keys, addrs.v4addrs), 1763 }, 1764 { 1765 .key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1766 .offset = offsetof(struct flow_keys, addrs.v6addrs), 1767 }, 1768 { 1769 .key_id = FLOW_DISSECTOR_KEY_TIPC, 1770 .offset = offsetof(struct flow_keys, addrs.tipckey), 1771 }, 1772 { 1773 .key_id = FLOW_DISSECTOR_KEY_PORTS, 1774 .offset = offsetof(struct flow_keys, ports), 1775 }, 1776 { 1777 .key_id = FLOW_DISSECTOR_KEY_VLAN, 1778 .offset = offsetof(struct flow_keys, vlan), 1779 }, 1780 { 1781 .key_id = FLOW_DISSECTOR_KEY_FLOW_LABEL, 1782 .offset = offsetof(struct flow_keys, tags), 1783 }, 1784 { 1785 .key_id = FLOW_DISSECTOR_KEY_GRE_KEYID, 1786 .offset = offsetof(struct flow_keys, keyid), 1787 }, 1788 }; 1789 1790 static const struct flow_dissector_key flow_keys_dissector_symmetric_keys[] = { 1791 { 1792 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1793 .offset = offsetof(struct flow_keys, control), 1794 }, 1795 { 1796 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1797 .offset = offsetof(struct flow_keys, basic), 1798 }, 1799 { 1800 .key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS, 1801 .offset = offsetof(struct flow_keys, addrs.v4addrs), 1802 }, 1803 { 1804 .key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS, 1805 .offset = offsetof(struct flow_keys, addrs.v6addrs), 1806 }, 1807 { 1808 .key_id = FLOW_DISSECTOR_KEY_PORTS, 1809 .offset = offsetof(struct flow_keys, ports), 1810 }, 1811 }; 1812 1813 static const struct flow_dissector_key flow_keys_basic_dissector_keys[] = { 1814 { 1815 .key_id = FLOW_DISSECTOR_KEY_CONTROL, 1816 .offset = offsetof(struct flow_keys, control), 1817 }, 1818 { 1819 .key_id = FLOW_DISSECTOR_KEY_BASIC, 1820 .offset = offsetof(struct flow_keys, basic), 1821 }, 1822 }; 1823 1824 struct flow_dissector flow_keys_dissector __read_mostly; 1825 EXPORT_SYMBOL(flow_keys_dissector); 1826 1827 struct flow_dissector flow_keys_basic_dissector __read_mostly; 1828 EXPORT_SYMBOL(flow_keys_basic_dissector); 1829 1830 static int __init init_default_flow_dissectors(void) 1831 { 1832 skb_flow_dissector_init(&flow_keys_dissector, 1833 flow_keys_dissector_keys, 1834 ARRAY_SIZE(flow_keys_dissector_keys)); 1835 skb_flow_dissector_init(&flow_keys_dissector_symmetric, 1836 flow_keys_dissector_symmetric_keys, 1837 ARRAY_SIZE(flow_keys_dissector_symmetric_keys)); 1838 skb_flow_dissector_init(&flow_keys_basic_dissector, 1839 flow_keys_basic_dissector_keys, 1840 ARRAY_SIZE(flow_keys_basic_dissector_keys)); 1841 return 0; 1842 } 1843 1844 core_initcall(init_default_flow_dissectors); 1845