ip.c revision 36285 
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 1.38.2.26 1998/05/06 23:50:11 brian Exp $
21 *
22 *	TODO:
23 *		o Return ICMP message for filterd packet
24 *		  and optionaly record it into log.
25 */
26#include <sys/types.h>
27#include <sys/socket.h>
28#include <netinet/in.h>
29#include <netinet/in_systm.h>
30#include <netinet/ip.h>
31#include <netinet/ip_icmp.h>
32#include <netinet/udp.h>
33#include <netinet/tcp.h>
34#include <arpa/inet.h>
35#include <net/if_tun.h>
36#include <sys/un.h>
37
38#ifndef NOALIAS
39#include <alias.h>
40#endif
41#include <errno.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45#include <unistd.h>
46
47#include "mbuf.h"
48#include "log.h"
49#include "defs.h"
50#include "timer.h"
51#include "fsm.h"
52#include "lqr.h"
53#include "hdlc.h"
54#include "loadalias.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#include "bundle.h"
66#include "vjcomp.h"
67#include "tun.h"
68#include "ip.h"
69
70static const u_short interactive_ports[32] = {
71  544, 513, 514, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
72  0, 0, 0, 0, 0, 21, 22, 23, 0, 0, 0, 0, 0, 0, 0, 543,
73};
74
75#define	INTERACTIVE(p)	(interactive_ports[(p) & 0x1F] == (p))
76
77static const char *TcpFlags[] = { "FIN", "SYN", "RST", "PSH", "ACK", "URG" };
78
79static int
80PortMatch(int op, u_short pport, u_short rport)
81{
82  switch (op) {
83    case OP_EQ:
84    return (pport == rport);
85  case OP_GT:
86    return (pport > rport);
87  case OP_LT:
88    return (pport < rport);
89  default:
90    return (0);
91  }
92}
93
94/*
95 *  Check a packet against with defined filters
96 */
97static int
98FilterCheck(struct ip *pip, struct filter *filter)
99{
100  int gotinfo, cproto, estab, syn, finrst, n, len, didname;
101  struct tcphdr *th;
102  struct udphdr *uh;
103  struct icmp *ih;
104  char *ptop;
105  u_short sport, dport;
106  struct filterent *fp = filter->rule;
107  char dbuff[100];
108
109  if (fp->action) {
110    cproto = gotinfo = estab = syn = finrst = didname = 0;
111    sport = dport = 0;
112    for (n = 0; n < MAXFILTERS; n++) {
113      if (fp->action) {
114	/* permit fragments on in and out filter */
115        if (filter->fragok && (ntohs(pip->ip_off) & IP_OFFMASK) != 0)
116	  return (A_PERMIT);
117
118        if (!didname)
119          log_Printf(LogDEBUG, "%s filter:\n", filter->name);
120        didname = 1;
121
122	if ((pip->ip_src.s_addr & fp->smask.s_addr) ==
123	    (fp->saddr.s_addr & fp->smask.s_addr) &&
124	    (pip->ip_dst.s_addr & fp->dmask.s_addr) ==
125	    (fp->daddr.s_addr & fp->dmask.s_addr)) {
126	  if (fp->proto) {
127	    if (!gotinfo) {
128	      ptop = (char *) pip + (pip->ip_hl << 2);
129
130	      switch (pip->ip_p) {
131	      case IPPROTO_ICMP:
132		cproto = P_ICMP;
133		ih = (struct icmp *) ptop;
134		sport = ih->icmp_type;
135		estab = syn = finrst = -1;
136                if (log_IsKept(LogDEBUG))
137		  snprintf(dbuff, sizeof dbuff, "sport = %d", sport);
138		break;
139	      case IPPROTO_UDP:
140		cproto = P_UDP;
141		uh = (struct udphdr *) ptop;
142		sport = ntohs(uh->uh_sport);
143		dport = ntohs(uh->uh_dport);
144		estab = syn = finrst = -1;
145                if (log_IsKept(LogDEBUG))
146		  snprintf(dbuff, sizeof dbuff, "sport = %d, dport = %d",
147                           sport, dport);
148		break;
149	      case IPPROTO_TCP:
150		cproto = P_TCP;
151		th = (struct tcphdr *) ptop;
152		sport = ntohs(th->th_sport);
153		dport = ntohs(th->th_dport);
154		estab = (th->th_flags & TH_ACK);
155		syn = (th->th_flags & TH_SYN);
156		finrst = (th->th_flags & (TH_FIN|TH_RST));
157                if (log_IsKept(LogDEBUG) && !estab)
158		  snprintf(dbuff, sizeof dbuff,
159                           "flags = %02x, sport = %d, dport = %d",
160                           th->th_flags, sport, dport);
161		break;
162	      default:
163		return (A_DENY);       /* We'll block unknown type of packet */
164	      }
165              if (log_IsKept(LogDEBUG)) {
166                if (estab != -1) {
167                  len = strlen(dbuff);
168                  snprintf(dbuff + len, sizeof dbuff - len,
169                           ", estab = %d, syn = %d, finrst = %d",
170                           estab, syn, finrst);
171                }
172	        log_Printf(LogDEBUG, " Filter: proto = %s, %s\n",
173                          filter_Proto2Nam(cproto), dbuff);
174              }
175	      gotinfo = 1;
176	    }
177            if (log_IsKept(LogDEBUG)) {
178	      if (fp->opt.srcop != OP_NONE) {
179                snprintf(dbuff, sizeof dbuff, ", src %s %d",
180                         filter_Op2Nam(fp->opt.srcop), fp->opt.srcport);
181                len = strlen(dbuff);
182              } else
183                len = 0;
184	      if (fp->opt.dstop != OP_NONE) {
185                snprintf(dbuff + len, sizeof dbuff - len,
186                         ", dst %s %d", filter_Op2Nam(fp->opt.dstop),
187                         fp->opt.dstport);
188              } else if (!len)
189                *dbuff = '\0';
190
191	      log_Printf(LogDEBUG, "  rule = %d: Address match, "
192                        "check against proto %s%s, action = %s\n",
193                        n, filter_Proto2Nam(fp->proto),
194                        dbuff, filter_Action2Nam(fp->action));
195            }
196
197	    if (cproto == fp->proto) {
198	      if ((fp->opt.srcop == OP_NONE ||
199		   PortMatch(fp->opt.srcop, sport, fp->opt.srcport)) &&
200		  (fp->opt.dstop == OP_NONE ||
201		   PortMatch(fp->opt.dstop, dport, fp->opt.dstport)) &&
202		  (fp->opt.estab == 0 || estab) &&
203		  (fp->opt.syn == 0 || syn) &&
204		  (fp->opt.finrst == 0 || finrst)) {
205		return (fp->action);
206	      }
207	    }
208	  } else {
209	    /* Address is mached. Make a decision. */
210	    log_Printf(LogDEBUG, "  rule = %d: Address match, action = %s\n", n,
211                      filter_Action2Nam(fp->action));
212	    return (fp->action);
213	  }
214	} else
215	  log_Printf(LogDEBUG, "  rule = %d: Address mismatch\n", n);
216      }
217      fp++;
218    }
219    return (A_DENY);		/* No rule is mached. Deny this packet */
220  }
221  return (A_PERMIT);		/* No rule is given. Permit this packet */
222}
223
224#ifdef notdef
225static void
226IcmpError(struct ip * pip, int code)
227{
228  struct mbuf *bp;
229
230  if (pip->ip_p != IPPROTO_ICMP) {
231    bp = mbuf_Alloc(cnt, MB_IPIN);
232    memcpy(MBUF_CTOP(bp), ptr, cnt);
233    vj_SendFrame(bp);
234    ipcp_AddOutOctets(cnt);
235  }
236}
237#endif
238
239/*
240 *  For debugging aid.
241 */
242int
243PacketCheck(struct bundle *bundle, char *cp, int nb, struct filter *filter)
244{
245  struct ip *pip;
246  struct tcphdr *th;
247  struct udphdr *uh;
248  struct icmp *icmph;
249  char *ptop;
250  int mask, len, n;
251  int pri = PRI_NORMAL;
252  int logit, loglen;
253  static char logbuf[200];
254
255  logit = log_IsKept(LogTCPIP) && filter->logok;
256  loglen = 0;
257
258  pip = (struct ip *) cp;
259
260  if (logit && loglen < sizeof logbuf) {
261    snprintf(logbuf + loglen, sizeof logbuf - loglen, "%s ", filter->name);
262    loglen += strlen(logbuf + loglen);
263  }
264  ptop = (cp + (pip->ip_hl << 2));
265
266  switch (pip->ip_p) {
267  case IPPROTO_ICMP:
268    if (logit && loglen < sizeof logbuf) {
269      icmph = (struct icmp *) ptop;
270      snprintf(logbuf + loglen, sizeof logbuf - loglen,
271	     "ICMP: %s:%d ---> ", inet_ntoa(pip->ip_src), icmph->icmp_type);
272      loglen += strlen(logbuf + loglen);
273      snprintf(logbuf + loglen, sizeof logbuf - loglen,
274	       "%s:%d", inet_ntoa(pip->ip_dst), icmph->icmp_type);
275      loglen += strlen(logbuf + loglen);
276    }
277    break;
278  case IPPROTO_UDP:
279    if (logit && loglen < sizeof logbuf) {
280      uh = (struct udphdr *) ptop;
281      snprintf(logbuf + loglen, sizeof logbuf - loglen,
282	   "UDP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(uh->uh_sport));
283      loglen += strlen(logbuf + loglen);
284      snprintf(logbuf + loglen, sizeof logbuf - loglen,
285	       "%s:%d", inet_ntoa(pip->ip_dst), ntohs(uh->uh_dport));
286      loglen += strlen(logbuf + loglen);
287    }
288    break;
289  case IPPROTO_TCP:
290    th = (struct tcphdr *) ptop;
291    if (pip->ip_tos == IPTOS_LOWDELAY)
292      pri = PRI_FAST;
293    else if ((ntohs(pip->ip_off) & IP_OFFMASK) == 0) {
294      if (INTERACTIVE(ntohs(th->th_sport)) || INTERACTIVE(ntohs(th->th_dport)))
295	pri = PRI_FAST;
296    }
297    if (logit && loglen < sizeof logbuf) {
298      len = ntohs(pip->ip_len) - (pip->ip_hl << 2) - (th->th_off << 2);
299      snprintf(logbuf + loglen, sizeof logbuf - loglen,
300	   "TCP: %s:%d ---> ", inet_ntoa(pip->ip_src), ntohs(th->th_sport));
301      loglen += strlen(logbuf + loglen);
302      snprintf(logbuf + loglen, sizeof logbuf - loglen,
303	       "%s:%d", inet_ntoa(pip->ip_dst), ntohs(th->th_dport));
304      loglen += strlen(logbuf + loglen);
305      n = 0;
306      for (mask = TH_FIN; mask != 0x40; mask <<= 1) {
307	if (th->th_flags & mask) {
308	  snprintf(logbuf + loglen, sizeof logbuf - loglen, " %s", TcpFlags[n]);
309	  loglen += strlen(logbuf + loglen);
310	}
311	n++;
312      }
313      snprintf(logbuf + loglen, sizeof logbuf - loglen,
314	       "  seq:%x  ack:%x (%d/%d)",
315	       ntohl(th->th_seq), ntohl(th->th_ack), len, nb);
316      loglen += strlen(logbuf + loglen);
317      if ((th->th_flags & TH_SYN) && nb > 40) {
318	u_short *sp;
319
320	ptop += 20;
321	sp = (u_short *) ptop;
322	if (ntohs(sp[0]) == 0x0204) {
323	  snprintf(logbuf + loglen, sizeof logbuf - loglen,
324		   " MSS = %d", ntohs(sp[1]));
325	  loglen += strlen(logbuf + loglen);
326	}
327      }
328    }
329    break;
330  }
331
332  if ((FilterCheck(pip, filter) & A_DENY)) {
333    if (logit)
334      log_Printf(LogTCPIP, "%s - BLOCKED\n", logbuf);
335#ifdef notdef
336    if (direction == 0)
337      IcmpError(pip, pri);
338#endif
339    return (-1);
340  } else {
341    /* Check Keep Alive filter */
342    if (logit) {
343      if (FilterCheck(pip, &bundle->filter.alive) & A_DENY)
344        log_Printf(LogTCPIP, "%s - NO KEEPALIVE\n", logbuf);
345      else
346        log_Printf(LogTCPIP, "%s\n", logbuf);
347    }
348    return (pri);
349  }
350}
351
352void
353ip_Input(struct bundle *bundle, struct mbuf * bp)
354{
355  u_char *cp;
356  struct mbuf *wp;
357  int nb, nw;
358  struct tun_data tun;
359  struct ip *pip = (struct ip *)tun.data;
360
361  tun_fill_header(tun, AF_INET);
362  cp = tun.data;
363  nb = 0;
364  for (wp = bp; wp; wp = wp->next) {	/* Copy to contiguous region */
365    if (sizeof tun.data - (cp - tun.data) < wp->cnt) {
366      log_Printf(LogERROR, "ip_Input: Packet too large (%d) - dropped\n",
367                mbuf_Length(bp));
368      mbuf_Free(bp);
369      return;
370    }
371    memcpy(cp, MBUF_CTOP(wp), wp->cnt);
372    cp += wp->cnt;
373    nb += wp->cnt;
374  }
375
376#ifndef NOALIAS
377  if (alias_IsEnabled()) {
378    struct tun_data *frag;
379    int iresult;
380    char *fptr;
381
382    iresult = (*PacketAlias.In)(tun.data, sizeof tun.data);
383    nb = ntohs(((struct ip *) tun.data)->ip_len);
384
385    if (nb > MAX_MRU) {
386      log_Printf(LogERROR, "ip_Input: Problem with IP header length\n");
387      mbuf_Free(bp);
388      return;
389    }
390    if (iresult == PKT_ALIAS_OK
391	|| iresult == PKT_ALIAS_FOUND_HEADER_FRAGMENT) {
392      if (PacketCheck(bundle, tun.data, nb, &bundle->filter.in) < 0) {
393	mbuf_Free(bp);
394	return;
395      }
396
397      if (!(FilterCheck(pip, &bundle->filter.alive) & A_DENY))
398        bundle_StartIdleTimer(bundle);
399
400      ipcp_AddInOctets(&bundle->ncp.ipcp, nb);
401
402      nb = ntohs(((struct ip *) tun.data)->ip_len);
403      nb += sizeof tun - sizeof tun.data;
404      nw = write(bundle->dev.fd, &tun, nb);
405      if (nw != nb) {
406        if (nw == -1)
407	  log_Printf(LogERROR, "ip_Input: wrote %d, got %s\n", nb,
408                    strerror(errno));
409        else
410	  log_Printf(LogERROR, "ip_Input: wrote %d, got %d\n", nb, nw);
411      }
412
413      if (iresult == PKT_ALIAS_FOUND_HEADER_FRAGMENT) {
414	while ((fptr = (*PacketAlias.GetFragment)(tun.data)) != NULL) {
415	  (*PacketAlias.FragmentIn)(tun.data, fptr);
416	  nb = ntohs(((struct ip *) fptr)->ip_len);
417          frag = (struct tun_data *)
418	    ((char *)fptr - sizeof tun + sizeof tun.data);
419          nb += sizeof tun - sizeof tun.data;
420	  nw = write(bundle->dev.fd, frag, nb);
421	  if (nw != nb) {
422            if (nw == -1)
423	      log_Printf(LogERROR, "ip_Input: wrote %d, got %s\n", nb,
424                        strerror(errno));
425            else
426	      log_Printf(LogERROR, "ip_Input: wrote %d, got %d\n", nb, nw);
427          }
428	  free(frag);
429	}
430      }
431    } else if (iresult == PKT_ALIAS_UNRESOLVED_FRAGMENT) {
432      nb = ntohs(((struct ip *) tun.data)->ip_len);
433      nb += sizeof tun - sizeof tun.data;
434      frag = (struct tun_data *)malloc(nb);
435      if (frag == NULL)
436	log_Printf(LogALERT, "ip_Input: Cannot allocate memory for fragment\n");
437      else {
438        tun_fill_header(*frag, AF_INET);
439	memcpy(frag->data, tun.data, nb - sizeof tun + sizeof tun.data);
440	(*PacketAlias.SaveFragment)(frag->data);
441      }
442    }
443  } else
444#endif /* #ifndef NOALIAS */
445  {			/* no aliasing */
446    if (PacketCheck(bundle, tun.data, nb, &bundle->filter.in) < 0) {
447      mbuf_Free(bp);
448      return;
449    }
450
451    if (!(FilterCheck(pip, &bundle->filter.alive) & A_DENY))
452      bundle_StartIdleTimer(bundle);
453
454    ipcp_AddInOctets(&bundle->ncp.ipcp, nb);
455
456    nb += sizeof tun - sizeof tun.data;
457    nw = write(bundle->dev.fd, &tun, nb);
458    if (nw != nb) {
459      if (nw == -1)
460	log_Printf(LogERROR, "ip_Input: wrote %d, got %s\n", nb, strerror(errno));
461      else
462        log_Printf(LogERROR, "ip_Input: wrote %d, got %d\n", nb, nw);
463    }
464  }
465  mbuf_Free(bp);
466}
467
468static struct mqueue IpOutputQueues[PRI_FAST + 1];
469
470void
471ip_Enqueue(int pri, char *ptr, int count)
472{
473  struct mbuf *bp;
474
475  bp = mbuf_Alloc(count, MB_IPQ);
476  memcpy(MBUF_CTOP(bp), ptr, count);
477  mbuf_Enqueue(&IpOutputQueues[pri], bp);
478}
479
480int
481ip_QueueLen()
482{
483  struct mqueue *queue;
484  int result = 0;
485
486  for (queue = &IpOutputQueues[PRI_MAX]; queue >= IpOutputQueues; queue--)
487    result += queue->qlen;
488
489  return result;
490}
491
492int
493ip_FlushPacket(struct link *l, struct bundle *bundle)
494{
495  struct mqueue *queue;
496  struct mbuf *bp;
497  int cnt;
498
499  if (bundle->ncp.ipcp.fsm.state != ST_OPENED)
500    return 0;
501
502  for (queue = &IpOutputQueues[PRI_FAST]; queue >= IpOutputQueues; queue--)
503    if (queue->top) {
504      bp = mbuf_Dequeue(queue);
505      if (bp) {
506        struct ip *pip = (struct ip *)MBUF_CTOP(bp);
507
508	cnt = mbuf_Length(bp);
509	vj_SendFrame(l, bp, bundle);
510        if (!(FilterCheck(pip, &bundle->filter.alive) & A_DENY))
511          bundle_StartIdleTimer(bundle);
512        ipcp_AddOutOctets(&bundle->ncp.ipcp, cnt);
513	return 1;
514      }
515    }
516
517  return 0;
518}
519