ip.c revision 49372
1/* 2 * PPP IP Protocol Interface 3 * 4 * Written by Toshiharu OHNO (tony-o@iij.ad.jp) 5 * 6 * Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd. 7 * 8 * Redistribution and use in source and binary forms are permitted 9 * provided that the above copyright notice and this paragraph are 10 * duplicated in all such forms and that any documentation, 11 * advertising materials, and other materials related to such 12 * distribution and use acknowledge that the software was developed 13 * by the Internet Initiative Japan. The name of the 14 * IIJ may not be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED 18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. 19 * 20 * $Id: ip.c,v 1.65 1999/07/27 23:43:59 brian Exp $ 21 * 22 * TODO: 23 * o Return ICMP message for filterd packet 24 * and optionaly record it into log. 25 */ 26#include <sys/param.h> 27#if defined(__OpenBSD__) || defined(__NetBSD__) 28#include <sys/socket.h> 29#endif 30#include <netinet/in.h> 31#include <netinet/in_systm.h> 32#include <netinet/ip.h> 33#include <netinet/ip_icmp.h> 34#include <netinet/udp.h> 35#include <netinet/tcp.h> 36#include <arpa/inet.h> 37#include <sys/un.h> 38 39#include <errno.h> 40#include <stdio.h> 41#include <stdlib.h> 42#include <string.h> 43#include <termios.h> 44#include <unistd.h> 45 46#include "layer.h" 47#include "proto.h" 48#include "mbuf.h" 49#include "log.h" 50#include "defs.h" 51#include "timer.h" 52#include "fsm.h" 53#include "lqr.h" 54#include "hdlc.h" 55#include "throughput.h" 56#include "iplist.h" 57#include "slcompress.h" 58#include "ipcp.h" 59#include "filter.h" 60#include "descriptor.h" 61#include "lcp.h" 62#include "ccp.h" 63#include "link.h" 64#include "mp.h" 65#ifndef NORADIUS 66#include "radius.h" 67#endif 68#include "bundle.h" 69#include "vjcomp.h" 70#include "tun.h" 71#include "ip.h" 72 73static const u_short interactive_ports[32] = { 74 544, 513, 514, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 75 80, 81, 0, 0, 0, 21, 22, 23, 0, 0, 0, 0, 0, 0, 0, 543, 76}; 77 78#define INTERACTIVE(p) (interactive_ports[(p) & 0x1F] == (p)) 79 80static const char *TcpFlags[] = { "FIN", "SYN", "RST", "PSH", "ACK", "URG" }; 81 82static __inline int 83PortMatch(int op, u_short pport, u_short rport) 84{ 85 switch (op) { 86 case OP_EQ: 87 return (pport == rport); 88 case OP_GT: 89 return (pport > rport); 90 case OP_LT: 91 return (pport < rport); 92 default: 93 return (0); 94 } 95} 96 97/* 98 * Check a packet against a defined filter 99 * Returns 0 to accept the packet, non-zero to drop the packet 100 * 101 * If filtering is enabled, the initial fragment of a datagram must 102 * contain the complete protocol header, and subsequent fragments 103 * must not attempt to over-write it. 104 */ 105static int 106FilterCheck(const struct ip *pip, const struct filter *filter) 107{ 108 int gotinfo; /* true if IP payload decoded */ 109 int cproto; /* P_* protocol type if (gotinfo) */ 110 int estab, syn, finrst; /* TCP state flags if (gotinfo) */ 111 u_short sport, dport; /* src, dest port from packet if (gotinfo) */ 112 int n; /* filter rule to process */ 113 int len; /* bytes used in dbuff */ 114 int didname; /* true if filter header printed */ 115 int match; /* true if condition matched */ 116 const struct filterent *fp = filter->rule; 117 char dbuff[100]; 118 119 if (fp->f_action == A_NONE) 120 return (0); /* No rule is given. Permit this packet */ 121 122 /* Deny any packet fragment that tries to over-write the header. 123 * Since we no longer have the real header available, punt on the 124 * largest normal header - 20 bytes for TCP without options, rounded 125 * up to the next possible fragment boundary. Since the smallest 126 * `legal' MTU is 576, and the smallest recommended MTU is 296, any 127 * fragmentation within this range is dubious at best */ 128 len = ntohs(pip->ip_off) & IP_OFFMASK; /* fragment offset */ 129 if (len > 0) { /* Not first fragment within datagram */ 130 if (len < (24 >> 3)) /* don't allow fragment to over-write header */ 131 return (1); 132 /* permit fragments on in and out filter */ 133 return (filter->fragok); 134 } 135 136 cproto = gotinfo = estab = syn = finrst = didname = 0; 137 sport = dport = 0; 138 for (n = 0; n < MAXFILTERS; ) { 139 if (fp->f_action == A_NONE) { 140 n++; 141 fp++; 142 continue; 143 } 144 145 if (!didname) { 146 log_Printf(LogDEBUG, "%s filter:\n", filter->name); 147 didname = 1; 148 } 149 150 match = 0; 151 if (!((pip->ip_src.s_addr ^ fp->f_src.ipaddr.s_addr) & 152 fp->f_src.mask.s_addr) && 153 !((pip->ip_dst.s_addr ^ fp->f_dst.ipaddr.s_addr) & 154 fp->f_dst.mask.s_addr)) { 155 if (fp->f_proto != P_NONE) { 156 if (!gotinfo) { 157 const char *ptop = (const char *) pip + (pip->ip_hl << 2); 158 const struct tcphdr *th; 159 const struct udphdr *uh; 160 const struct icmp *ih; 161 int datalen; /* IP datagram length */ 162 163 datalen = ntohs(pip->ip_len) - (pip->ip_hl << 2); 164 switch (pip->ip_p) { 165 case IPPROTO_ICMP: 166 cproto = P_ICMP; 167 if (datalen < 8) /* ICMP must be at least 8 octets */ 168 return (1); 169 ih = (const struct icmp *) ptop; 170 sport = ih->icmp_type; 171 estab = syn = finrst = -1; 172 if (log_IsKept(LogDEBUG)) 173 snprintf(dbuff, sizeof dbuff, "sport = %d", sport); 174 break; 175 case IPPROTO_IGMP: 176 cproto = P_IGMP; 177 if (datalen < 8) /* IGMP uses 8-octet messages */ 178 return (1); 179 estab = syn = finrst = -1; 180 sport = ntohs(0); 181 break; 182 case IPPROTO_OSPFIGP: 183 cproto = P_OSPF; 184 if (datalen < 8) /* IGMP uses 8-octet messages */ 185 return (1); 186 estab = syn = finrst = -1; 187 sport = ntohs(0); 188 break; 189 case IPPROTO_UDP: 190 case IPPROTO_IPIP: 191 cproto = P_UDP; 192 if (datalen < 8) /* UDP header is 8 octets */ 193 return (1); 194 uh = (const struct udphdr *) ptop; 195 sport = ntohs(uh->uh_sport); 196 dport = ntohs(uh->uh_dport); 197 estab = syn = finrst = -1; 198 if (log_IsKept(LogDEBUG)) 199 snprintf(dbuff, sizeof dbuff, "sport = %d, dport = %d", 200 sport, dport); 201 break; 202 case IPPROTO_TCP: 203 cproto = P_TCP; 204 th = (const struct tcphdr *) ptop; 205 /* TCP headers are variable length. The following code 206 * ensures that the TCP header length isn't de-referenced if 207 * the datagram is too short 208 */ 209 if (datalen < 20 || datalen < (th->th_off << 2)) 210 return (1); 211 sport = ntohs(th->th_sport); 212 dport = ntohs(th->th_dport); 213 estab = (th->th_flags & TH_ACK); 214 syn = (th->th_flags & TH_SYN); 215 finrst = (th->th_flags & (TH_FIN|TH_RST)); 216 if (log_IsKept(LogDEBUG)) { 217 if (!estab) 218 snprintf(dbuff, sizeof dbuff, 219 "flags = %02x, sport = %d, dport = %d", 220 th->th_flags, sport, dport); 221 else 222 *dbuff = '\0'; 223 } 224 break; 225 default: 226 return (1); /* We'll block unknown type of packet */ 227 } 228 229 if (log_IsKept(LogDEBUG)) { 230 if (estab != -1) { 231 len = strlen(dbuff); 232 snprintf(dbuff + len, sizeof dbuff - len, 233 ", estab = %d, syn = %d, finrst = %d", 234 estab, syn, finrst); 235 } 236 log_Printf(LogDEBUG, " Filter: proto = %s, %s\n", 237 filter_Proto2Nam(cproto), dbuff); 238 } 239 gotinfo = 1; 240 } 241 if (log_IsKept(LogDEBUG)) { 242 if (fp->f_srcop != OP_NONE) { 243 snprintf(dbuff, sizeof dbuff, ", src %s %d", 244 filter_Op2Nam(fp->f_srcop), fp->f_srcport); 245 len = strlen(dbuff); 246 } else 247 len = 0; 248 if (fp->f_dstop != OP_NONE) { 249 snprintf(dbuff + len, sizeof dbuff - len, 250 ", dst %s %d", filter_Op2Nam(fp->f_dstop), 251 fp->f_dstport); 252 } else if (!len) 253 *dbuff = '\0'; 254 255 log_Printf(LogDEBUG, " rule = %d: Address match, " 256 "check against proto %s%s, action = %s\n", 257 n, filter_Proto2Nam(fp->f_proto), 258 dbuff, filter_Action2Nam(fp->f_action)); 259 } 260 261 if (cproto == fp->f_proto) { 262 if ((fp->f_srcop == OP_NONE || 263 PortMatch(fp->f_srcop, sport, fp->f_srcport)) && 264 (fp->f_dstop == OP_NONE || 265 PortMatch(fp->f_dstop, dport, fp->f_dstport)) && 266 (fp->f_estab == 0 || estab) && 267 (fp->f_syn == 0 || syn) && 268 (fp->f_finrst == 0 || finrst)) { 269 match = 1; 270 } 271 } 272 } else { 273 /* Address is matched and no protocol specified. Make a decision. */ 274 log_Printf(LogDEBUG, " rule = %d: Address match, action = %s\n", n, 275 filter_Action2Nam(fp->f_action)); 276 match = 1; 277 } 278 } else 279 log_Printf(LogDEBUG, " rule = %d: Address mismatch\n", n); 280 281 if (match != fp->f_invert) { 282 /* Take specified action */ 283 if (fp->f_action < A_NONE) 284 fp = &filter->rule[n = fp->f_action]; 285 else 286 return (fp->f_action != A_PERMIT); 287 } else { 288 n++; 289 fp++; 290 } 291 } 292 return (1); /* No rule is mached. Deny this packet */ 293} 294 295#ifdef notdef 296static void 297IcmpError(struct ip *pip, int code) 298{ 299 struct mbuf *bp; 300 301 if (pip->ip_p != IPPROTO_ICMP) { 302 bp = mbuf_Alloc(cnt, MB_IPIN); 303 memcpy(MBUF_CTOP(bp), ptr, cnt); 304 vj_SendFrame(bp); 305 ipcp_AddOutOctets(cnt); 306 } 307} 308#endif 309 310/* 311 * For debugging aid. 312 */ 313int 314PacketCheck(struct bundle *bundle, char *cp, int nb, struct filter *filter) 315{ 316 struct ip *pip; 317 struct tcphdr *th; 318 struct udphdr *uh; 319 struct icmp *icmph; 320 char *ptop; 321 int mask, len, n; 322 int pri = PRI_NORMAL; 323 int logit, loglen; 324 char logbuf[200]; 325 326 logit = log_IsKept(LogTCPIP) && filter->logok; 327 loglen = 0; 328 329 pip = (struct ip *) cp; 330 331 if (logit && loglen < sizeof logbuf) { 332 snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s ", filter->name); 333 loglen += strlen(logbuf + loglen); 334 } 335 ptop = (cp + (pip->ip_hl << 2)); 336 337 switch (pip->ip_p) { 338 case IPPROTO_ICMP: 339 if (logit && loglen < sizeof logbuf) { 340 icmph = (struct icmp *) ptop; 341 snprintf(logbuf + loglen, sizeof logbuf - loglen, 342 "ICMP: %s:%d ---> ", inet_ntoa(pip->ip_src), icmph->icmp_type); 343 loglen += strlen(logbuf + loglen); 344 snprintf(logbuf + loglen, sizeof logbuf - loglen, 345 "%s:%d", inet_ntoa(pip->ip_dst), icmph->icmp_type); 346 loglen += strlen(logbuf + loglen); 347 } 348 break; 349 case IPPROTO_UDP: 350 if (logit && loglen < sizeof logbuf) { 351 uh = (struct udphdr *) ptop; 352 snprintf(logbuf + loglen, sizeof logbuf - loglen, 353 "UDP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); 354 loglen += strlen(logbuf + loglen); 355 snprintf(logbuf + loglen, sizeof logbuf - loglen, 356 "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); 357 loglen += strlen(logbuf + loglen); 358 } 359 break; 360 case IPPROTO_OSPFIGP: 361 if (logit && loglen < sizeof logbuf) { 362 snprintf(logbuf + loglen, sizeof logbuf - loglen, 363 "OSPF: %s ---> ", inet_ntoa(pip->ip_src)); 364 loglen += strlen(logbuf + loglen); 365 snprintf(logbuf + loglen, sizeof logbuf - loglen, 366 "%s", inet_ntoa(pip->ip_dst)); 367 loglen += strlen(logbuf + loglen); 368 } 369 break; 370 case IPPROTO_IPIP: 371 if (logit && loglen < sizeof logbuf) { 372 uh = (struct udphdr *) ptop; 373 snprintf(logbuf + loglen, sizeof logbuf - loglen, 374 "IPIP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); 375 loglen += strlen(logbuf + loglen); 376 snprintf(logbuf + loglen, sizeof logbuf - loglen, 377 "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); 378 loglen += strlen(logbuf + loglen); 379 } 380 break; 381 case IPPROTO_IGMP: 382 if (logit && loglen < sizeof logbuf) { 383 uh = (struct udphdr *) ptop; 384 snprintf(logbuf + loglen, sizeof logbuf - loglen, 385 "IGMP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport)); 386 loglen += strlen(logbuf + loglen); 387 snprintf(logbuf + loglen, sizeof logbuf - loglen, 388 "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport)); 389 loglen += strlen(logbuf + loglen); 390 } 391 break; 392 case IPPROTO_TCP: 393 th = (struct tcphdr *) ptop; 394 if (pip->ip_tos == IPTOS_LOWDELAY) 395 pri = PRI_FAST; 396 else if ((ntohs(pip->ip_off) & IP_OFFMASK) == 0) { 397 if (INTERACTIVE(ntohs(th->th_sport)) || INTERACTIVE(ntohs(th->th_dport))) 398 pri = PRI_FAST; 399 } 400 if (logit && loglen < sizeof logbuf) { 401 len = ntohs(pip->ip_len) - (pip->ip_hl << 2) - (th->th_off << 2); 402 snprintf(logbuf + loglen, sizeof logbuf - loglen, 403 "TCP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(th->th_sport)); 404 loglen += strlen(logbuf + loglen); 405 snprintf(logbuf + loglen, sizeof logbuf - loglen, 406 "%s:%d", inet_ntoa(pip->ip_dst), ntohs(th->th_dport)); 407 loglen += strlen(logbuf + loglen); 408 n = 0; 409 for (mask = TH_FIN; mask != 0x40; mask <<= 1) { 410 if (th->th_flags & mask) { 411 snprintf(logbuf + loglen, sizeof logbuf - loglen, " %s", TcpFlags[n]); 412 loglen += strlen(logbuf + loglen); 413 } 414 n++; 415 } 416 snprintf(logbuf + loglen, sizeof logbuf - loglen, 417 " seq:%lx ack:%lx (%d/%d)", 418 (u_long)ntohl(th->th_seq), (u_long)ntohl(th->th_ack), len, nb); 419 loglen += strlen(logbuf + loglen); 420 if ((th->th_flags & TH_SYN) && nb > 40) { 421 u_short *sp; 422 423 ptop += 20; 424 sp = (u_short *) ptop; 425 if (ntohs(sp[0]) == 0x0204) { 426 snprintf(logbuf + loglen, sizeof logbuf - loglen, 427 " MSS = %d", ntohs(sp[1])); 428 loglen += strlen(logbuf + loglen); 429 } 430 } 431 } 432 break; 433 } 434 435 if (FilterCheck(pip, filter)) { 436 if (logit) 437 log_Printf(LogTCPIP, "%s - BLOCKED\n", logbuf); 438#ifdef notdef 439 if (direction == 0) 440 IcmpError(pip, pri); 441#endif 442 return (-1); 443 } else { 444 /* Check Keep Alive filter */ 445 if (logit) { 446 if (FilterCheck(pip, &bundle->filter.alive)) 447 log_Printf(LogTCPIP, "%s - NO KEEPALIVE\n", logbuf); 448 else 449 log_Printf(LogTCPIP, "%s\n", logbuf); 450 } 451 return (pri); 452 } 453} 454 455struct mbuf * 456ip_Input(struct bundle *bundle, struct link *l, struct mbuf *bp) 457{ 458 int nb, nw; 459 struct tun_data tun; 460 struct ip *pip; 461 462 if (bundle->ncp.ipcp.fsm.state != ST_OPENED) { 463 log_Printf(LogWARN, "ip_Input: IPCP not open - packet dropped\n"); 464 mbuf_Free(bp); 465 return NULL; 466 } 467 468 mbuf_SetType(bp, MB_IPIN); 469 tun_fill_header(tun, AF_INET); 470 nb = mbuf_Length(bp); 471 if (nb > sizeof tun.data) { 472 log_Printf(LogWARN, "ip_Input: %s: Packet too large (got %d, max %d)\n", 473 l->name, nb, (int)(sizeof tun.data)); 474 mbuf_Free(bp); 475 return NULL; 476 } 477 mbuf_Read(bp, tun.data, nb); 478 479 if (PacketCheck(bundle, tun.data, nb, &bundle->filter.in) < 0) 480 return NULL; 481 482 pip = (struct ip *)tun.data; 483 if (!FilterCheck(pip, &bundle->filter.alive)) 484 bundle_StartIdleTimer(bundle); 485 486 ipcp_AddInOctets(&bundle->ncp.ipcp, nb); 487 488 nb += sizeof tun - sizeof tun.data; 489 nw = write(bundle->dev.fd, &tun, nb); 490 if (nw != nb) { 491 if (nw == -1) 492 log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %s\n", 493 l->name, nb, strerror(errno)); 494 else 495 log_Printf(LogERROR, "ip_Input: %s: wrote %d, got %d\n", l->name, nb, nw); 496 } 497 498 return NULL; 499} 500 501void 502ip_Enqueue(struct ipcp *ipcp, int pri, char *ptr, int count) 503{ 504 struct mbuf *bp; 505 506 if (pri < 0 || pri > sizeof ipcp->Queue / sizeof ipcp->Queue[0]) 507 log_Printf(LogERROR, "Can't store in ip queue %d\n", pri); 508 else { 509 /* 510 * We allocate an extra 6 bytes, four at the front and two at the end. 511 * This is an optimisation so that we need to do less work in 512 * mbuf_Prepend() in acf_LayerPush() and proto_LayerPush() and 513 * appending in hdlc_LayerPush(). 514 */ 515 bp = mbuf_Alloc(count + 6, MB_IPOUT); 516 bp->offset += 4; 517 bp->cnt -= 6; 518 memcpy(MBUF_CTOP(bp), ptr, count); 519 mbuf_Enqueue(&ipcp->Queue[pri], bp); 520 } 521} 522 523void 524ip_DeleteQueue(struct ipcp *ipcp) 525{ 526 struct mqueue *queue; 527 528 for (queue = ipcp->Queue; queue < ipcp->Queue + PRI_MAX; queue++) 529 while (queue->top) 530 mbuf_Free(mbuf_Dequeue(queue)); 531} 532 533int 534ip_QueueLen(struct ipcp *ipcp) 535{ 536 struct mqueue *queue; 537 int result = 0; 538 539 for (queue = ipcp->Queue; queue < ipcp->Queue + PRI_MAX; queue++) 540 result += queue->qlen; 541 542 return result; 543} 544 545int 546ip_PushPacket(struct link *l, struct bundle *bundle) 547{ 548 struct ipcp *ipcp = &bundle->ncp.ipcp; 549 struct mqueue *queue; 550 struct mbuf *bp; 551 struct ip *pip; 552 int cnt; 553 554 if (ipcp->fsm.state != ST_OPENED) 555 return 0; 556 557 for (queue = &ipcp->Queue[PRI_FAST]; queue >= ipcp->Queue; queue--) 558 if (queue->top) { 559 bp = mbuf_Contiguous(mbuf_Dequeue(queue)); 560 cnt = mbuf_Length(bp); 561 pip = (struct ip *)MBUF_CTOP(bp); 562 if (!FilterCheck(pip, &bundle->filter.alive)) 563 bundle_StartIdleTimer(bundle); 564 link_PushPacket(l, bp, bundle, PRI_NORMAL, PROTO_IP); 565 ipcp_AddOutOctets(ipcp, cnt); 566 return 1; 567 } 568 569 return 0; 570} 571