1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1996 - 2001 Brian Somers <brian@Awfulhak.org>
5 *          based on work by Toshiharu OHNO <tony-o@iij.ad.jp>
6 *                           Internet Initiative Japan, Inc (IIJ)
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * $FreeBSD: stable/11/usr.sbin/ppp/main.c 330449 2018-03-05 07:26:05Z eadler $
31 */
32
33#include <sys/param.h>
34#include <netinet/in.h>
35#include <netinet/in_systm.h>
36#include <netinet/ip.h>
37#include <sys/un.h>
38#include <sys/socket.h>
39#include <net/route.h>
40
41#include <errno.h>
42#include <fcntl.h>
43#include <paths.h>
44#include <signal.h>
45#include <stdarg.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#include <sys/time.h>
50#include <termios.h>
51#include <unistd.h>
52#include <sys/stat.h>
53
54#ifndef NONAT
55#ifdef LOCALNAT
56#include "alias.h"
57#else
58#include <alias.h>
59#endif
60#endif
61
62#include "layer.h"
63#include "probe.h"
64#include "mbuf.h"
65#include "log.h"
66#include "defs.h"
67#include "id.h"
68#include "timer.h"
69#include "fsm.h"
70#include "lqr.h"
71#include "hdlc.h"
72#include "lcp.h"
73#include "ccp.h"
74#include "iplist.h"
75#include "throughput.h"
76#include "slcompress.h"
77#include "ncpaddr.h"
78#include "ipcp.h"
79#include "filter.h"
80#include "descriptor.h"
81#include "link.h"
82#include "mp.h"
83#ifndef NORADIUS
84#include "radius.h"
85#endif
86#include "ipv6cp.h"
87#include "ncp.h"
88#include "bundle.h"
89#include "auth.h"
90#include "systems.h"
91#include "sig.h"
92#include "main.h"
93#include "server.h"
94#include "prompt.h"
95#include "chat.h"
96#include "chap.h"
97#include "cbcp.h"
98#include "datalink.h"
99#include "iface.h"
100
101#ifndef O_NONBLOCK
102#ifdef O_NDELAY
103#define	O_NONBLOCK O_NDELAY
104#endif
105#endif
106
107static void DoLoop(struct bundle *);
108static void TerminalStop(int);
109
110static struct bundle *SignalBundle;
111static struct prompt *SignalPrompt;
112struct libalias *la;
113
114void
115Cleanup()
116{
117  SignalBundle->CleaningUp = 1;
118  bundle_Close(SignalBundle, NULL, CLOSE_STAYDOWN);
119}
120
121void
122AbortProgram(int excode)
123{
124  if (SignalBundle)
125    server_Close(SignalBundle);
126  log_Printf(LogPHASE, "PPP Terminated (%s).\n", ex_desc(excode));
127  if (SignalBundle) {
128    bundle_Close(SignalBundle, NULL, CLOSE_STAYDOWN);
129    bundle_Destroy(SignalBundle);
130  }
131  log_Close();
132  exit(excode);
133}
134
135static void
136CloseConnection(int signo)
137{
138  /* NOTE, these are manual, we've done a setsid() */
139  sig_signal(SIGINT, SIG_IGN);
140  log_Printf(LogPHASE, "Caught signal %d, abort connection(s)\n", signo);
141  bundle_Down(SignalBundle, CLOSE_STAYDOWN);
142  sig_signal(SIGINT, CloseConnection);
143}
144
145static void
146CloseSession(int signo)
147{
148  log_Printf(LogPHASE, "Signal %d, terminate.\n", signo);
149  Cleanup();
150}
151
152static pid_t BGPid = 0;
153
154static void
155KillChild(int signo)
156{
157  signal(signo, SIG_IGN);
158  log_Printf(LogPHASE, "Parent: Signal %d\n", signo);
159  kill(BGPid, SIGINT);
160}
161
162static void
163TerminalCont(int signo __unused)
164{
165  signal(SIGCONT, SIG_DFL);
166  prompt_Continue(SignalPrompt);
167}
168
169static void
170TerminalStop(int signo __unused)
171{
172  prompt_Suspend(SignalPrompt);
173  signal(SIGCONT, TerminalCont);
174  raise(SIGSTOP);
175}
176
177static void
178BringDownServer(int signo __unused)
179{
180  /* Drops all child prompts too ! */
181  if (server_Close(SignalBundle))
182    log_Printf(LogPHASE, "Closed server socket\n");
183}
184
185static void
186RestartServer(int signo __unused)
187{
188  /* Drops all child prompts and re-opens the socket */
189  server_Reopen(SignalBundle);
190}
191
192static void
193Usage(void)
194{
195  fprintf(stderr, "usage: ppp [-auto | -foreground | -background | -direct |"
196          " -dedicated | -ddial | -interactive]"
197#ifndef NONAT
198          " [-nat]"
199#endif
200          " [-quiet] [-unit N] [system ...]\n");
201  exit(EX_START);
202}
203
204struct switches {
205  unsigned nat : 1;
206  unsigned fg : 1;
207  unsigned quiet : 1;
208  int mode;
209  int unit;
210};
211
212static int
213ProcessArgs(int argc, char **argv, struct switches *sw)
214{
215  int optc, newmode, arg;
216  char *cp;
217
218  optc = 0;
219  memset(sw, '\0', sizeof *sw);
220  sw->mode = PHYS_INTERACTIVE;
221  sw->unit = -1;
222
223  for (arg = 1; arg < argc && *argv[arg] == '-'; arg++, optc++) {
224    cp = argv[arg] + 1;
225    newmode = Nam2mode(cp);
226    switch (newmode) {
227      case PHYS_NONE:
228        if (strcmp(cp, "nat") == 0) {
229#ifdef NONAT
230          log_Printf(LogWARN, "%s ignored: NAT is compiled out\n", argv[arg]);
231#else
232          sw->nat = 1;
233#endif
234          optc--;			/* this option isn't exclusive */
235        } else if (strcmp(cp, "alias") == 0) {
236#ifdef NONAT
237          log_Printf(LogWARN, "%s ignored: NAT is compiled out\n", argv[arg]);
238          fprintf(stderr, "%s ignored: NAT is compiled out\n", argv[arg]);
239#else
240          log_Printf(LogWARN, "%s is deprecated\n", argv[arg]);
241          fprintf(stderr, "%s is deprecated\n", argv[arg]);
242          sw->nat = 1;
243#endif
244          optc--;			/* this option isn't exclusive */
245        } else if (strncmp(cp, "unit", 4) == 0) {
246          optc--;			/* this option isn't exclusive */
247          if (cp[4] == '\0') {
248            optc--;			/* nor is the argument */
249            if (++arg == argc) {
250              fprintf(stderr, "-unit: Expected unit number\n");
251              Usage();
252            } else
253              sw->unit = atoi(argv[arg]);
254          } else
255            sw->unit = atoi(cp + 4);
256        } else if (strcmp(cp, "quiet") == 0) {
257          sw->quiet = 1;
258          optc--;			/* this option isn't exclusive */
259        } else
260          Usage();
261        break;
262
263      case PHYS_ALL:
264        Usage();
265        break;
266
267      default:
268        sw->mode = newmode;
269        if (newmode == PHYS_FOREGROUND)
270          sw->fg = 1;
271    }
272  }
273
274  if (optc > 1) {
275    fprintf(stderr, "You may specify only one mode.\n");
276    exit(EX_START);
277  }
278
279  if (sw->mode == PHYS_AUTO && arg == argc) {
280    fprintf(stderr, "A system must be specified in auto mode.\n");
281    exit(EX_START);
282  }
283
284  return arg;		/* Don't SetLabel yet ! */
285}
286
287static void
288CheckLabel(const char *label, struct prompt *prompt, int mode)
289{
290  const char *err;
291
292  if ((err = system_IsValid(label, prompt, mode)) != NULL) {
293    fprintf(stderr, "%s: %s\n", label, err);
294    if (mode == PHYS_DIRECT)
295      log_Printf(LogWARN, "Label %s rejected -direct connection: %s\n",
296                 label, err);
297    log_Close();
298    exit(1);
299  }
300}
301
302
303int
304main(int argc, char **argv)
305{
306  char *name;
307  const char *lastlabel;
308  int arg, holdfd[3], label;
309  unsigned f;
310  struct bundle *bundle;
311  struct prompt *prompt;
312  struct switches sw;
313
314  probe_Init();
315
316  /*
317   * We open 3 descriptors to ensure that STDIN_FILENO, STDOUT_FILENO and
318   * STDERR_FILENO are always open.  These are closed before DoLoop(),
319   * but *after* we've avoided the possibility of erroneously closing
320   * an important descriptor with close(STD{IN,OUT,ERR}_FILENO).
321   */
322  if ((holdfd[0] = open(_PATH_DEVNULL, O_RDWR)) == -1) {
323    fprintf(stderr, "Cannot open %s !\n", _PATH_DEVNULL);
324    return 2;
325  }
326  for (f = 1; f < sizeof holdfd / sizeof *holdfd; f++)
327    holdfd[f] = dup(holdfd[0]);
328
329  name = strrchr(argv[0], '/');
330  log_Open(name ? name + 1 : argv[0]);
331
332#ifndef NONAT
333  la = LibAliasInit(NULL);
334#endif
335  label = ProcessArgs(argc, argv, &sw);
336
337  /*
338   * A FreeBSD & OpenBSD hack to dodge a bug in the tty driver that drops
339   * output occasionally.... I must find the real reason some time.  To
340   * display the dodgy behaviour, comment out this bit, make yourself a large
341   * routing table and then run ppp in interactive mode.  The `show route'
342   * command will drop chunks of data !!!
343   */
344  if (sw.mode == PHYS_INTERACTIVE) {
345    close(STDIN_FILENO);
346    if (open(_PATH_TTY, O_RDONLY) != STDIN_FILENO) {
347      fprintf(stderr, "Cannot open %s for input !\n", _PATH_TTY);
348      return 2;
349    }
350  }
351
352  /* Allow output for the moment (except in direct mode) */
353  if (sw.mode == PHYS_DIRECT)
354    prompt = NULL;
355  else
356    SignalPrompt = prompt = prompt_Create(NULL, NULL, PROMPT_STD);
357
358  ID0init();
359  if (ID0realuid() != 0) {
360    char conf[200], *ptr;
361
362    snprintf(conf, sizeof conf, "%s/%s", PPP_CONFDIR, CONFFILE);
363    do {
364      struct stat sb;
365
366      if (stat(conf, &sb) == 0 && sb.st_mode & S_IWOTH) {
367        log_Printf(LogALERT, "ppp: Access violation: Please protect %s\n",
368                   conf);
369        return -1;
370      }
371      ptr = conf + strlen(conf)-2;
372      while (ptr > conf && *ptr != '/')
373        *ptr-- = '\0';
374    } while (ptr >= conf);
375  }
376
377  if (label < argc)
378    for (arg = label; arg < argc; arg++)
379      CheckLabel(argv[arg], prompt, sw.mode);
380  else
381    CheckLabel("default", prompt, sw.mode);
382
383  if (!sw.quiet)
384    prompt_Printf(prompt, "Working in %s mode\n", mode2Nam(sw.mode));
385
386  if ((bundle = bundle_Create(TUN_PREFIX, sw.mode, sw.unit)) == NULL)
387    return EX_START;
388
389  /* NOTE:  We may now have changed argv[1] via a ``set proctitle'' */
390
391  SignalBundle = bundle;
392  bundle->NatEnabled = sw.nat;
393  if (sw.nat)
394    opt_enable(bundle, OPT_IFACEALIAS);
395
396  if (system_Select(bundle, "default", CONFFILE, prompt, NULL) < 0)
397    prompt_Printf(prompt, "Warning: No default entry found in config file.\n");
398
399  sig_signal(SIGHUP, CloseSession);
400  sig_signal(SIGTERM, CloseSession);
401  sig_signal(SIGINT, CloseConnection);
402  sig_signal(SIGQUIT, CloseSession);
403  sig_signal(SIGALRM, SIG_IGN);
404  signal(SIGPIPE, SIG_IGN);
405
406  if (sw.mode == PHYS_INTERACTIVE)
407    sig_signal(SIGTSTP, TerminalStop);
408
409  sig_signal(SIGUSR1, RestartServer);
410  sig_signal(SIGUSR2, BringDownServer);
411
412  lastlabel = argv[argc - 1];
413  for (arg = label; arg < argc; arg++) {
414    /* In case we use LABEL or ``set enddisc label'' */
415    bundle_SetLabel(bundle, lastlabel);
416    system_Select(bundle, argv[arg], CONFFILE, prompt, NULL);
417  }
418
419  if (label < argc)
420    /* In case the last label did a ``load'' */
421    bundle_SetLabel(bundle, lastlabel);
422
423  if (sw.mode == PHYS_AUTO &&
424      ncprange_family(&bundle->ncp.ipcp.cfg.peer_range) == AF_UNSPEC) {
425    prompt_Printf(prompt, "You must ``set ifaddr'' with a peer address "
426                  "in auto mode.\n");
427    AbortProgram(EX_START);
428  }
429
430  if (prompt) {
431    prompt->bundle = bundle;	/* couldn't do it earlier */
432    if (!sw.quiet)
433      prompt_Printf(prompt, "Using interface: %s\n", bundle->iface->name);
434  }
435
436  if (sw.mode != PHYS_INTERACTIVE) {
437    if (sw.mode != PHYS_DIRECT) {
438      if (!sw.fg) {
439        int bgpipe[2];
440        pid_t bgpid;
441
442        if (sw.mode == PHYS_BACKGROUND && pipe(bgpipe)) {
443          log_Printf(LogERROR, "pipe: %s\n", strerror(errno));
444	  AbortProgram(EX_SOCK);
445        }
446
447        bgpid = fork();
448        if (bgpid == -1) {
449	  log_Printf(LogERROR, "fork: %s\n", strerror(errno));
450	  AbortProgram(EX_SOCK);
451        }
452
453        if (bgpid) {
454	  char c = EX_NORMAL;
455          int ret;
456
457	  if (sw.mode == PHYS_BACKGROUND) {
458	    close(bgpipe[1]);
459	    BGPid = bgpid;
460            /* If we get a signal, kill the child */
461            signal(SIGHUP, KillChild);
462            signal(SIGTERM, KillChild);
463            signal(SIGINT, KillChild);
464            signal(SIGQUIT, KillChild);
465
466	    /* Wait for our child to close its pipe before we exit */
467            while ((ret = read(bgpipe[0], &c, 1)) == 1) {
468              switch (c) {
469                case EX_NORMAL:
470                  if (!sw.quiet) {
471	            prompt_Printf(prompt, "PPP enabled\n");
472	            log_Printf(LogPHASE, "Parent: PPP enabled\n");
473                  }
474	          break;
475                case EX_REDIAL:
476                  if (!sw.quiet)
477	            prompt_Printf(prompt, "Attempting redial\n");
478                  continue;
479                case EX_RECONNECT:
480                  if (!sw.quiet)
481	            prompt_Printf(prompt, "Attempting reconnect\n");
482                  continue;
483	        default:
484	          prompt_Printf(prompt, "Child failed (%s)\n",
485                                ex_desc((int)c));
486	          log_Printf(LogPHASE, "Parent: Child failed (%s)\n",
487		             ex_desc((int) c));
488	      }
489	      break;
490            }
491            if (ret != 1) {
492	      prompt_Printf(prompt, "Child exit, no status.\n");
493	      log_Printf(LogPHASE, "Parent: Child exit, no status.\n");
494	    }
495	    close(bgpipe[0]);
496	  }
497	  return c;
498        } else if (sw.mode == PHYS_BACKGROUND) {
499	  close(bgpipe[0]);
500          bundle->notify.fd = bgpipe[1];
501        }
502
503        bundle_ChangedPID(bundle);
504        bundle_LockTun(bundle);	/* we have a new pid */
505      }
506
507      /* -auto, -dedicated, -ddial, -foreground & -background */
508      prompt_Destroy(prompt, 0);
509      close(STDOUT_FILENO);
510      close(STDERR_FILENO);
511      close(STDIN_FILENO);
512      if (!sw.fg)
513        setsid();
514    } else {
515      /*
516       * -direct - STDIN_FILENO gets used by physical_Open.  STDOUT_FILENO
517       * *may* get used in exec/pipe mode.
518       */
519      prompt_TtyInit(NULL);
520      close(STDERR_FILENO);
521    }
522  } else {
523    /* -interactive */
524    close(STDERR_FILENO);
525    prompt_TtyInit(prompt);
526    prompt_TtyCommandMode(prompt);
527    prompt_Required(prompt);
528  }
529
530  /* We can get rid of these now */
531  for (f = 0; f < sizeof holdfd / sizeof *holdfd; f++)
532    close(holdfd[f]);
533
534  log_Printf(LogPHASE, "PPP Started (%s mode).\n", mode2Nam(sw.mode));
535  DoLoop(bundle);
536  AbortProgram(EX_NORMAL);
537
538  return EX_NORMAL;
539}
540
541static void
542DoLoop(struct bundle *bundle)
543{
544  fd_set *rfds, *wfds, *efds;
545  int i, nfds, nothing_done;
546
547  if ((rfds = mkfdset()) == NULL) {
548    log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
549    return;
550  }
551
552  if ((wfds = mkfdset()) == NULL) {
553    log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
554    free(rfds);
555    return;
556  }
557
558  if ((efds = mkfdset()) == NULL) {
559    log_Printf(LogERROR, "DoLoop: Cannot create fd_set\n");
560    free(rfds);
561    free(wfds);
562    return;
563  }
564
565  for (; !bundle_IsDead(bundle); bundle_CleanDatalinks(bundle)) {
566    nfds = 0;
567    zerofdset(rfds);
568    zerofdset(wfds);
569    zerofdset(efds);
570
571    /* All our datalinks, the tun device and the MP socket */
572    descriptor_UpdateSet(&bundle->desc, rfds, wfds, efds, &nfds);
573
574    /* All our prompts and the diagnostic socket */
575    descriptor_UpdateSet(&server.desc, rfds, NULL, NULL, &nfds);
576
577    bundle_CleanDatalinks(bundle);
578    if (bundle_IsDead(bundle))
579      /* Don't select - we'll be here forever */
580      break;
581
582    /*
583     * It's possible that we've had a signal since we last checked.  If
584     * we don't check again before calling select(), we may end up stuck
585     * after having missed the event.... sig_Handle() tries to be as
586     * quick as possible if nothing is likely to have happened.
587     * This is only really likely if we block in open(... O_NONBLOCK)
588     * which will happen with a misconfigured device.
589     */
590    if (sig_Handle())
591      continue;
592
593    i = select(nfds, rfds, wfds, efds, NULL);
594
595    if (i < 0 && errno != EINTR) {
596      log_Printf(LogERROR, "DoLoop: select(): %s\n", strerror(errno));
597      if (log_IsKept(LogTIMER)) {
598        struct timeval t;
599
600        for (i = 0; i <= nfds; i++) {
601          if (FD_ISSET(i, rfds)) {
602            log_Printf(LogTIMER, "Read set contains %d\n", i);
603            FD_CLR(i, rfds);
604            t.tv_sec = t.tv_usec = 0;
605            if (select(nfds, rfds, wfds, efds, &t) != -1) {
606              log_Printf(LogTIMER, "The culprit !\n");
607              break;
608            }
609          }
610          if (FD_ISSET(i, wfds)) {
611            log_Printf(LogTIMER, "Write set contains %d\n", i);
612            FD_CLR(i, wfds);
613            t.tv_sec = t.tv_usec = 0;
614            if (select(nfds, rfds, wfds, efds, &t) != -1) {
615              log_Printf(LogTIMER, "The culprit !\n");
616              break;
617            }
618          }
619          if (FD_ISSET(i, efds)) {
620            log_Printf(LogTIMER, "Error set contains %d\n", i);
621            FD_CLR(i, efds);
622            t.tv_sec = t.tv_usec = 0;
623            if (select(nfds, rfds, wfds, efds, &t) != -1) {
624              log_Printf(LogTIMER, "The culprit !\n");
625              break;
626            }
627          }
628        }
629      }
630      break;
631    }
632
633    log_Printf(LogTIMER, "Select returns %d\n", i);
634
635    sig_Handle();
636
637    if (i <= 0)
638      continue;
639
640    for (i = 0; i <= nfds; i++)
641      if (FD_ISSET(i, efds)) {
642        log_Printf(LogPHASE, "Exception detected on descriptor %d\n", i);
643        /* We deal gracefully with link descriptor exceptions */
644        if (!bundle_Exception(bundle, i)) {
645          log_Printf(LogERROR, "Exception cannot be handled !\n");
646          break;
647        }
648      }
649
650    if (i <= nfds)
651      break;
652
653    nothing_done = 1;
654
655    if (descriptor_IsSet(&server.desc, rfds)) {
656      descriptor_Read(&server.desc, bundle, rfds);
657      nothing_done = 0;
658    }
659
660    if (descriptor_IsSet(&bundle->desc, rfds)) {
661      descriptor_Read(&bundle->desc, bundle, rfds);
662      nothing_done = 0;
663    }
664
665    if (descriptor_IsSet(&bundle->desc, wfds))
666      if (descriptor_Write(&bundle->desc, bundle, wfds) <= 0 && nothing_done) {
667        /*
668         * This is disastrous.  The OS has told us that something is
669         * writable, and all our write()s have failed.  Rather than
670         * going back immediately to do our UpdateSet()s and select(),
671         * we sleep for a bit to avoid gobbling up all cpu time.
672         */
673        struct timeval t;
674
675        t.tv_sec = 0;
676        t.tv_usec = 100000;
677        select(0, NULL, NULL, NULL, &t);
678      }
679  }
680
681  log_Printf(LogDEBUG, "DoLoop done.\n");
682}
683