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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 | /* * INET An implementation of the TCP/IP protocol suite for the LINUX * operating system. INET is implemented using the BSD Socket * interface as the means of communication with the user level. * * The Internet Protocol (IP) module. * * Version: @(#)ip.c 1.0.16b 9/1/93 * * Authors: Ross Biro, <bir7@leland.Stanford.Edu> * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> * Donald Becker, <becker@super.org> * Alan Cox, <Alan.Cox@linux.org> * Richard Underwood * Stefan Becker, <stefanb@yello.ping.de> * Jorge Cwik, <jorge@laser.satlink.net> * Arnt Gulbrandsen, <agulbra@nvg.unit.no> * * * Fixes: * Alan Cox : Commented a couple of minor bits of surplus code * Alan Cox : Undefining IP_FORWARD doesn't include the code * (just stops a compiler warning). * Alan Cox : Frames with >=MAX_ROUTE record routes, strict routes or loose routes * are junked rather than corrupting things. * Alan Cox : Frames to bad broadcast subnets are dumped * We used to process them non broadcast and * boy could that cause havoc. * Alan Cox : ip_forward sets the free flag on the * new frame it queues. Still crap because * it copies the frame but at least it * doesn't eat memory too. * Alan Cox : Generic queue code and memory fixes. * Fred Van Kempen : IP fragment support (borrowed from NET2E) * Gerhard Koerting: Forward fragmented frames correctly. * Gerhard Koerting: Fixes to my fix of the above 8-). * Gerhard Koerting: IP interface addressing fix. * Linus Torvalds : More robustness checks * Alan Cox : Even more checks: Still not as robust as it ought to be * Alan Cox : Save IP header pointer for later * Alan Cox : ip option setting * Alan Cox : Use ip_tos/ip_ttl settings * Alan Cox : Fragmentation bogosity removed * (Thanks to Mark.Bush@prg.ox.ac.uk) * Dmitry Gorodchanin : Send of a raw packet crash fix. * Alan Cox : Silly ip bug when an overlength * fragment turns up. Now frees the * queue. * Linus Torvalds/ : Memory leakage on fragmentation * Alan Cox : handling. * Gerhard Koerting: Forwarding uses IP priority hints * Teemu Rantanen : Fragment problems. * Alan Cox : General cleanup, comments and reformat * Alan Cox : SNMP statistics * Alan Cox : BSD address rule semantics. Also see * UDP as there is a nasty checksum issue * if you do things the wrong way. * Alan Cox : Always defrag, moved IP_FORWARD to the config.in file * Alan Cox : IP options adjust sk->priority. * Pedro Roque : Fix mtu/length error in ip_forward. * Alan Cox : Avoid ip_chk_addr when possible. * Richard Underwood : IP multicasting. * Alan Cox : Cleaned up multicast handlers. * Alan Cox : RAW sockets demultiplex in the BSD style. * Gunther Mayer : Fix the SNMP reporting typo * Alan Cox : Always in group 224.0.0.1 * Pauline Middelink : Fast ip_checksum update when forwarding * Masquerading support. * Alan Cox : Multicast loopback error for 224.0.0.1 * Alan Cox : IP_MULTICAST_LOOP option. * Alan Cox : Use notifiers. * Bjorn Ekwall : Removed ip_csum (from slhc.c too) * Bjorn Ekwall : Moved ip_fast_csum to ip.h (inline!) * Stefan Becker : Send out ICMP HOST REDIRECT * Arnt Gulbrandsen : ip_build_xmit * Alan Cox : Per socket routing cache * Alan Cox : Fixed routing cache, added header cache. * Alan Cox : Loopback didn't work right in original ip_build_xmit - fixed it. * Alan Cox : Only send ICMP_REDIRECT if src/dest are the same net. * Alan Cox : Incoming IP option handling. * Alan Cox : Set saddr on raw output frames as per BSD. * Alan Cox : Stopped broadcast source route explosions. * Alan Cox : Can disable source routing * Takeshi Sone : Masquerading didn't work. * Dave Bonn,Alan Cox : Faster IP forwarding whenever possible. * Alan Cox : Memory leaks, tramples, misc debugging. * Alan Cox : Fixed multicast (by popular demand 8)) * Alan Cox : Fixed forwarding (by even more popular demand 8)) * Alan Cox : Fixed SNMP statistics [I think] * Gerhard Koerting : IP fragmentation forwarding fix * Alan Cox : Device lock against page fault. * Alan Cox : IP_HDRINCL facility. * Werner Almesberger : Zero fragment bug * Alan Cox : RAW IP frame length bug * Alan Cox : Outgoing firewall on build_xmit * A.N.Kuznetsov : IP_OPTIONS support throughout the kernel * Alan Cox : Multicast routing hooks * Jos Vos : Do accounting *before* call_in_firewall * Willy Konynenberg : Transparent proxying support * * * * To Fix: * IP fragmentation wants rewriting cleanly. The RFC815 algorithm is much more efficient * and could be made very efficient with the addition of some virtual memory hacks to permit * the allocation of a buffer that can then be 'grown' by twiddling page tables. * Output fragmentation wants updating along with the buffer management to use a single * interleaved copy algorithm so that fragmenting has a one copy overhead. Actual packet * output should probably do its own fragmentation at the UDP/RAW layer. TCP shouldn't cause * fragmentation anyway. * * FIXME: copy frag 0 iph to qp->iph * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <asm/segment.h> #include <asm/system.h> #include <linux/types.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/mm.h> #include <linux/string.h> #include <linux/errno.h> #include <linux/config.h> #include <linux/socket.h> #include <linux/sockios.h> #include <linux/in.h> #include <linux/inet.h> #include <linux/netdevice.h> #include <linux/etherdevice.h> #include <linux/proc_fs.h> #include <linux/stat.h> #include <net/snmp.h> #include <net/ip.h> #include <net/protocol.h> #include <net/route.h> #include <net/tcp.h> #include <net/udp.h> #include <linux/skbuff.h> #include <net/sock.h> #include <net/arp.h> #include <net/icmp.h> #include <net/raw.h> #include <net/checksum.h> #include <linux/igmp.h> #include <linux/ip_fw.h> #ifdef CONFIG_IP_MASQUERADE #include <net/ip_masq.h> #endif #include <linux/firewall.h> #include <linux/mroute.h> #include <net/netlink.h> #ifdef CONFIG_NET_ALIAS #include <linux/net_alias.h> #endif extern int last_retran; extern void sort_send(struct sock *sk); #define min(a,b) ((a)<(b)?(a):(b)) /* * SNMP management statistics */ #ifdef CONFIG_IP_FORWARD struct ip_mib ip_statistics={1,64,}; /* Forwarding=Yes, Default TTL=64 */ #else struct ip_mib ip_statistics={2,64,}; /* Forwarding=No, Default TTL=64 */ #endif /* * Handle the issuing of an ioctl() request * for the ip device. This is scheduled to * disappear */ int ip_ioctl(struct sock *sk, int cmd, unsigned long arg) { switch(cmd) { default: return(-EINVAL); } } #ifdef CONFIG_IP_TRANSPARENT_PROXY /* * Check the packet against our socket administration to see * if it is related to a connection on our system. * Needed for transparent proxying. */ int ip_chksock(struct sk_buff *skb) { switch (skb->h.iph->protocol) { case IPPROTO_ICMP: return icmp_chkaddr(skb); case IPPROTO_TCP: return tcp_chkaddr(skb); case IPPROTO_UDP: return udp_chkaddr(skb); default: return 0; } } #endif /* * This function receives all incoming IP datagrams. * * On entry skb->data points to the start of the IP header and * the MAC header has been removed. */ int ip_rcv(struct sk_buff *skb, struct device *dev, struct packet_type *pt) { struct iphdr *iph = skb->h.iph; struct sock *raw_sk=NULL; unsigned char hash; unsigned char flag = 0; struct inet_protocol *ipprot; int brd=IS_MYADDR; struct options * opt = NULL; int is_frag=0; __u32 daddr; #ifdef CONFIG_FIREWALL int fwres; __u16 rport; #endif #ifdef CONFIG_IP_MROUTE int mroute_pkt=0; #endif #ifdef CONFIG_NET_IPV6 /* * Intercept IPv6 frames. We dump ST-II and invalid types just below.. */ if(iph->version == 6) return ipv6_rcv(skb,dev,pt); #endif ip_statistics.IpInReceives++; /* * Account for the packet (even if the packet is * not accepted by the firewall!). */ #ifdef CONFIG_IP_ACCT ip_fw_chk(iph,dev,NULL,ip_acct_chain,0,IP_FW_MODE_ACCT_IN); #endif /* * Tag the ip header of this packet so we can find it */ skb->ip_hdr = iph; /* * RFC1122: 3.1.2.2 MUST silently discard any IP frame that fails the checksum. * RFC1122: 3.1.2.3 MUST discard a frame with invalid source address [NEEDS FIXING]. * * Is the datagram acceptable? * * 1. Length at least the size of an ip header * 2. Version of 4 * 3. Checksums correctly. [Speed optimisation for later, skip loopback checksums] * 4. Doesn't have a bogus length * (5. We ought to check for IP multicast addresses and undefined types.. does this matter ?) */ if (skb->len<sizeof(struct iphdr) || iph->ihl<5 || iph->version != 4 || ip_fast_csum((unsigned char *)iph, iph->ihl) !=0 || skb->len < ntohs(iph->tot_len)) { ip_statistics.IpInHdrErrors++; kfree_skb(skb, FREE_WRITE); return(0); } /* * Our transport medium may have padded the buffer out. Now we know it * is IP we can trim to the true length of the frame. * Note this now means skb->len holds ntohs(iph->tot_len). */ skb_trim(skb,ntohs(iph->tot_len)); /* * Try to select closest <src,dst> alias device, if any. * net_alias_dev_rx32 returns main device if it * fails to found other. * If successful, also incr. alias rx count. * * Only makes sense for unicasts - Thanks ANK. */ #ifdef CONFIG_NET_ALIAS if (skb->pkt_type == PACKET_HOST && iph->daddr != skb->dev->pa_addr && net_alias_has(skb->dev)) { skb->dev = dev = net_alias_dev_rx32(skb->dev, AF_INET, iph->saddr, iph->daddr); } #endif if (iph->ihl > 5) { skb->ip_summed = 0; if (ip_options_compile(NULL, skb)) return(0); opt = (struct options*)skb->proto_priv; #ifdef CONFIG_IP_NOSR if (opt->srr) { kfree_skb(skb, FREE_READ); return -EINVAL; } #endif } #if defined(CONFIG_IP_TRANSPARENT_PROXY) && !defined(CONFIG_IP_ALWAYS_DEFRAG) #define CONFIG_IP_ALWAYS_DEFRAG 1 #endif #ifdef CONFIG_IP_ALWAYS_DEFRAG /* * Defragment all incoming traffic before even looking at it. * If you have forwarding enabled, this makes the system a * defragmenting router. Not a common thing. * You probably DON'T want to enable this unless you have to. * You NEED to use this if you want to use transparent proxying, * otherwise, we can't vouch for your sanity. */ /* * See if the frame is fragmented. */ if(iph->frag_off) { if (iph->frag_off & htons(IP_MF)) is_frag|=IPFWD_FRAGMENT; /* * Last fragment ? */ if (iph->frag_off & htons(IP_OFFSET)) is_frag|=IPFWD_LASTFRAG; /* * Reassemble IP fragments. */ if(is_frag) { /* Defragment. Obtain the complete packet if there is one */ skb=ip_defrag(iph,skb,dev); if(skb==NULL) return 0; skb->dev = dev; iph=skb->h.iph; is_frag = 0; /* * When the reassembled packet gets forwarded, the ip * header checksum should be correct. * For better performance, this should actually only * be done in that particular case, i.e. set a flag * here and calculate the checksum in ip_forward. */ ip_send_check(iph); } } #endif /* * See if the firewall wants to dispose of the packet. */ #ifdef CONFIG_FIREWALL if ((fwres=call_in_firewall(PF_INET, skb->dev, iph, &rport))<FW_ACCEPT) { if(fwres==FW_REJECT) icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0, dev); kfree_skb(skb, FREE_WRITE); return 0; } #ifdef CONFIG_IP_TRANSPARENT_PROXY if (fwres==FW_REDIRECT) skb->redirport = rport; else #endif skb->redirport = 0; #endif #ifndef CONFIG_IP_ALWAYS_DEFRAG /* * Remember if the frame is fragmented. */ if(iph->frag_off) { if (iph->frag_off & htons(IP_MF)) is_frag|=IPFWD_FRAGMENT; /* * Last fragment ? */ if (iph->frag_off & htons(IP_OFFSET)) is_frag|=IPFWD_LASTFRAG; } #endif /* * Do any IP forwarding required. chk_addr() is expensive -- avoid it someday. * * This is inefficient. While finding out if it is for us we could also compute * the routing table entry. This is where the great unified cache theory comes * in as and when someone implements it * * For most hosts over 99% of packets match the first conditional * and don't go via ip_chk_addr. Note: brd is set to IS_MYADDR at * function entry. */ daddr = iph->daddr; #ifdef CONFIG_IP_TRANSPARENT_PROXY /* * ip_chksock adds still more overhead for forwarded traffic... */ if ( iph->daddr == skb->dev->pa_addr || skb->redirport || (brd = ip_chk_addr(iph->daddr)) != 0 || ip_chksock(skb)) #else if ( iph->daddr == skb->dev->pa_addr || (brd = ip_chk_addr(iph->daddr)) != 0) #endif { if (opt && opt->srr) { int srrspace, srrptr; __u32 nexthop; unsigned char * optptr = ((unsigned char *)iph) + opt->srr; if (brd != IS_MYADDR || skb->pkt_type != PACKET_HOST) { kfree_skb(skb, FREE_WRITE); return 0; } for ( srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4 ) { int brd2; if (srrptr + 3 > srrspace) { icmp_send(skb, ICMP_PARAMETERPROB, 0, opt->srr+2, skb->dev); kfree_skb(skb, FREE_WRITE); return 0; } memcpy(&nexthop, &optptr[srrptr-1], 4); if ((brd2 = ip_chk_addr(nexthop)) == 0) break; if (brd2 != IS_MYADDR) { /* * ANK: should we implement weak tunneling of multicasts? * Are they obsolete? DVMRP specs (RFC-1075) is old enough... * [They are obsolete] */ kfree_skb(skb, FREE_WRITE); return -EINVAL; } memcpy(&daddr, &optptr[srrptr-1], 4); } if (srrptr <= srrspace) { opt->srr_is_hit = 1; opt->is_changed = 1; if (sysctl_ip_forward) { if (ip_forward(skb, dev, is_frag, nexthop)) kfree_skb(skb, FREE_WRITE); } else { ip_statistics.IpInAddrErrors++; kfree_skb(skb, FREE_WRITE); } return 0; } } #ifdef CONFIG_IP_MULTICAST if(!(dev->flags&IFF_ALLMULTI) && brd==IS_MULTICAST && iph->daddr!=IGMP_ALL_HOSTS && !(dev->flags&IFF_LOOPBACK)) { /* * Check it is for one of our groups */ struct ip_mc_list *ip_mc=dev->ip_mc_list; do { if(ip_mc==NULL) { kfree_skb(skb, FREE_WRITE); return 0; } if(ip_mc->multiaddr==iph->daddr) break; ip_mc=ip_mc->next; } while(1); } #endif #ifndef CONFIG_IP_ALWAYS_DEFRAG /* * Reassemble IP fragments. */ if(is_frag) { /* Defragment. Obtain the complete packet if there is one */ skb=ip_defrag(iph,skb,dev); if(skb==NULL) return 0; skb->dev = dev; iph=skb->h.iph; } #endif #ifdef CONFIG_IP_MASQUERADE /* * Do we need to de-masquerade this packet? */ { int ret = ip_fw_demasquerade(&skb,dev); if (ret < 0) { kfree_skb(skb, FREE_WRITE); return 0; } if (ret) { struct iphdr *iph=skb->h.iph; if (ip_forward(skb, dev, IPFWD_MASQUERADED, iph->daddr)) kfree_skb(skb, FREE_WRITE); return 0; } } #endif /* * Point into the IP datagram, just past the header. */ skb->ip_hdr = iph; skb->h.raw += iph->ihl*4; #ifdef CONFIG_IP_MROUTE /* * Check the state on multicast routing (multicast and not 224.0.0.z) */ if(brd==IS_MULTICAST && (iph->daddr&htonl(0xFFFFFF00))!=htonl(0xE0000000)) mroute_pkt=1; #endif /* * Deliver to raw sockets. This is fun as to avoid copies we want to make no surplus copies. * * RFC 1122: SHOULD pass TOS value up to the transport layer. */ /* Note: See raw.c and net/raw.h, RAWV4_HTABLE_SIZE==MAX_INET_PROTOS */ hash = iph->protocol & (MAX_INET_PROTOS - 1); /* * If there maybe a raw socket we must check - if not we don't care less */ if((raw_sk = raw_v4_htable[hash]) != NULL) { struct sock *sknext = NULL; struct sk_buff *skb1; raw_sk = raw_v4_lookup(raw_sk, iph->protocol, iph->saddr, iph->daddr); if(raw_sk) { /* Any raw sockets */ do { /* Find the next */ sknext = raw_v4_lookup(raw_sk->next, iph->protocol, iph->saddr, iph->daddr); if(sknext) skb1 = skb_clone(skb, GFP_ATOMIC); else break; /* One pending raw socket left */ if(skb1) raw_rcv(raw_sk, skb1, dev, iph->saddr,daddr); raw_sk = sknext; } while(raw_sk!=NULL); /* * Here either raw_sk is the last raw socket, or NULL if none */ /* * We deliver to the last raw socket AFTER the protocol checks as it avoids a surplus copy */ } } /* * skb->h.raw now points at the protocol beyond the IP header. */ for (ipprot = (struct inet_protocol *)inet_protos[hash];ipprot != NULL;ipprot=(struct inet_protocol *)ipprot->next) { struct sk_buff *skb2; if (ipprot->protocol != iph->protocol) continue; /* * See if we need to make a copy of it. This will * only be set if more than one protocol wants it. * and then not for the last one. If there is a pending * raw delivery wait for that */ #ifdef CONFIG_IP_MROUTE if (ipprot->copy || raw_sk || mroute_pkt) #else if (ipprot->copy || raw_sk) #endif { skb2 = skb_clone(skb, GFP_ATOMIC); if(skb2==NULL) continue; } else { skb2 = skb; } flag = 1; /* * Pass on the datagram to each protocol that wants it, * based on the datagram protocol. We should really * check the protocol handler's return values here... */ ipprot->handler(skb2, dev, opt, daddr, (ntohs(iph->tot_len) - (iph->ihl * 4)), iph->saddr, 0, ipprot); } /* * All protocols checked. * If this packet was a broadcast, we may *not* reply to it, since that * causes (proven, grin) ARP storms and a leakage of memory (i.e. all * ICMP reply messages get queued up for transmission...) */ #ifdef CONFIG_IP_MROUTE /* * Forward the last copy to the multicast router. If * there is a pending raw delivery however make a copy * and forward that. */ if(mroute_pkt) { flag=1; if(raw_sk==NULL) ipmr_forward(skb, is_frag); else { struct sk_buff *skb2=skb_clone(skb, GFP_ATOMIC); if(skb2) { skb2->free=1; ipmr_forward(skb2, is_frag); } } } #endif if(raw_sk!=NULL) /* Shift to last raw user */ raw_rcv(raw_sk, skb, dev, iph->saddr, daddr); else if (!flag) /* Free and report errors */ { if (brd != IS_BROADCAST && brd!=IS_MULTICAST) icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PROT_UNREACH, 0, dev); kfree_skb(skb, FREE_WRITE); } return(0); } /* * Do any unicast IP forwarding required. */ /* * Don't forward multicast or broadcast frames. */ if(skb->pkt_type!=PACKET_HOST || brd==IS_BROADCAST) { kfree_skb(skb,FREE_WRITE); return 0; } /* * The packet is for another target. Forward the frame */ if (sysctl_ip_forward) { if (opt && opt->is_strictroute) { icmp_send(skb, ICMP_PARAMETERPROB, 0, 16, skb->dev); kfree_skb(skb, FREE_WRITE); return -1; } if (ip_forward(skb, dev, is_frag, iph->daddr)) kfree_skb(skb, FREE_WRITE); } else { /* printk("Machine %lx tried to use us as a forwarder to %lx but we have forwarding disabled!\n", iph->saddr,iph->daddr);*/ ip_statistics.IpInAddrErrors++; kfree_skb(skb, FREE_WRITE); } return(0); } |