/usr/src/usr.sbin/pppd/auth.c

Bug Summary

File:	src/usr.sbin/pppd/auth.c
Warning:	line 769, column 44 Access to field 'pw_uid' results in a dereference of a null pointer (loaded from variable 'pw')
Annotated Source Code

Press '?' to see keyboard shortcuts
Show analyzer invocation
clang -cc1 -cc1 -triple amd64-unknown-openbsd7.4 -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name auth.c -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -pic-is-pie -mframe-pointer=all -relaxed-aliasing -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -target-feature +retpoline-indirect-calls -target-feature +retpoline-indirect-branches -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/usr.sbin/pppd/obj -resource-dir /usr/local/llvm16/lib/clang/16 -I . -I /usr/src/usr.sbin/pppd/../../lib/libpcap -D HAVE_PATHS_H -D PPP_FILTER -internal-isystem /usr/local/llvm16/lib/clang/16/include -internal-externc-isystem /usr/include -O2 -fdebug-compilation-dir=/usr/src/usr.sbin/pppd/obj -ferror-limit 19 -fwrapv -D_RET_PROTECTOR -ret-protector -fcf-protection=branch -fno-jump-tables -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/scan/2024-01-11-140451-98009-1 -x c /usr/src/usr.sbin/pppd/auth.c
1/*	$OpenBSD: auth.c,v 1.40 2022/05/06 15:51:09 claudio Exp $	*/

3/*
* auth.c - PPP authentication and phase control.
*
* Copyright (c) 1989-2002 Paul Mackerras. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The name(s) of the authors of this software must not be used to
*    endorse or promote products derived from this software without
*    prior written permission.
*
* 4. Redistributions of any form whatsoever must retain the following
*    acknowledgment:
*    "This product includes software developed by Paul Mackerras
*     <paulus@samba.org>".
*
* THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
* SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Copyright (c) 1984-2000 Carnegie Mellon University. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The name "Carnegie Mellon University" must not be used to
*    endorse or promote products derived from this software without
*    prior written permission. For permission or any legal
*    details, please contact
*      Office of Technology Transfer
*      Carnegie Mellon University
*      5000 Forbes Avenue
*      Pittsburgh, PA  15213-3890
*      (412) 268-4387, fax: (412) 268-7395
*      tech-transfer@andrew.cmu.edu
*
* 4. Redistributions of any form whatsoever must retain the following
*    acknowledgment:
*    "This product includes software developed by Computing Services
*     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
*
* CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
* THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
* AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

76#include <stdio.h>
77#include <stddef.h>
78#include <stdlib.h>
79#include <unistd.h>
80#include <limits.h>
81#include <syslog.h>
82#include <pwd.h>
83#include <string.h>
84#include <sys/types.h>
85#include <sys/stat.h>
86#include <sys/socket.h>
87#include <utmp.h>
88#include <fcntl.h>
89#if defined(_PATH_LASTLOG"/var/log/lastlog") && defined(_linux_)
90#include <lastlog.h>
91#endif

93#include <netdb.h>
94#include <netinet/in.h>
95#include <arpa/inet.h>



99#include "pppd.h"
100#include "fsm.h"
101#include "lcp.h"
102#include "ipcp.h"
103#include "upap.h"
104#include "chap.h"
105#ifdef CBCP_SUPPORT
106#include "cbcp.h"
107#endif
108#include "pathnames.h"

110/* Used for storing a sequence of words.  Usually malloced. */
111struct wordlist {
  struct wordlist	*next;
  char		word[1];
114};

116/* Bits in scan_authfile return value */
117#define NONWILD_SERVER1	1
118#define NONWILD_CLIENT2	2

120#define ISWILD(word)(word[0] == '*' && word[1] == 0)	(word[0] == '*' && word[1] == 0)

122#define FALSE0	0
123#define TRUE1	1

125/* The name by which the peer authenticated itself to us. */
126char peer_authname[MAXNAMELEN256];

128/* Records which authentication operations haven't completed yet. */
129static int auth_pending[NUM_PPP1];

131/* Set if we have successfully called plogin() */
132static int logged_in;

134/* Set if we have run the /etc/ppp/auth-up script. */
135static int did_authup;

137/* List of addresses which the peer may use. */
138static struct wordlist *addresses[NUM_PPP1];

140/* Number of network protocols which we have opened. */
141static int num_np_open;

143/* Number of network protocols which have come up. */
144static int num_np_up;

146/* Set if we got the contents of passwd[] from the pap-secrets file. */
147static int passwd_from_file;

149/* Bits in auth_pending[] */
150#define PAP_WITHPEER1	1
151#define PAP_PEER2	2
152#define CHAP_WITHPEER4	4
153#define CHAP_PEER8	8

155extern char *crypt(const char *, const char *);

157/* Prototypes for procedures local to this file. */

159static void network_phase(int);
160static void check_idle(void *);
161static void connect_time_expired(void *);
162static int  plogin(char *, char *, char **, int *);
163static void plogout(void);
164static int  null_login(int);
165static int  get_pap_passwd(char *);
166static int  have_pap_secret(void);
167static int  have_chap_secret(char *, char *, u_int32_t);
168static int  ip_addr_check(u_int32_t, struct wordlist *);
169static int  scan_authfile(FILE *, char *, char *, u_int32_t, char *,
struct wordlist **, char *);
171static void free_wordlist(struct wordlist *);
172static void auth_script(char *);
173static void set_allowed_addrs(int, struct wordlist *);

175/*
* An Open on LCP has requested a change from Dead to Establish phase.
* Do what's necessary to bring the physical layer up.
*/
179void
180link_required(unit)
  int unit;
182{
183}

185/*
* LCP has terminated the link; go to the Dead phase and take the
* physical layer down.
*/
189void
190link_terminated(unit)
  int unit;
192{
  if (phase == PHASE_DEAD0)
return;
  if (logged_in)
plogout();
  phase = PHASE_DEAD0;
  syslog(LOG_NOTICE5, "Connection terminated.");
199}

201/*
* LCP has gone down; it will either die or try to re-establish.
*/
204void
205link_down(unit)
  int unit;
207{
  int i;
  struct protent *protp;

  if (did_authup) {
auth_script(_PATH_AUTHDOWN"/etc/ppp/auth-down");
did_authup = 0;
  }
  for (i = 0; (protp = protocols[i]) != NULL((void *)0); ++i) {
if (!protp->enabled_flag)
   continue;
      if (protp->protocol != PPP_LCP0xc021 && protp->lowerdown != NULL((void *)0))
   (*protp->lowerdown)(unit);
      if (protp->protocol < 0xC000 && protp->close != NULL((void *)0))
   (*protp->close)(unit, "LCP down");
  }
  num_np_open = 0;
  num_np_up = 0;
  if (phase != PHASE_DEAD0)
phase = PHASE_TERMINATE7;
227}

229/*
* The link is established.
* Proceed to the Dead, Authenticate or Network phase as appropriate.
*/
233void
234link_established(unit)
  int unit;
236{
  int auth;
  lcp_options *wo = &lcp_wantoptions[unit];
  lcp_options *go = &lcp_gotoptions[unit];
  lcp_options *ho = &lcp_hisoptions[unit];
  int i;
  struct protent *protp;

  /*
   * Tell higher-level protocols that LCP is up.
   */
  for (i = 0; (protp = protocols[i]) != NULL((void *)0); ++i)
      if (protp->protocol != PPP_LCP0xc021 && protp->enabled_flag
   && protp->lowerup != NULL((void *)0))
   (*protp->lowerup)(unit);

  if (auth_required && !(go->neg_chap || go->neg_upap)) {
/*
* We wanted the peer to authenticate itself, and it refused:
* treat it as though it authenticated with PAP using a username
* of "" and a password of "".  If that's not OK, boot it out.
*/
if (!wo->neg_upap || !null_login(unit)) {
   syslog(LOG_WARNING4, "peer refused to authenticate");
   lcp_close(unit, "peer refused to authenticate");
   return;
}
  }

  phase = PHASE_AUTHENTICATE4;
  auth = 0;
  if (go->neg_chap) {
ChapAuthPeer(unit, our_name, go->chap_mdtype);
auth |= CHAP_PEER8;
  } else if (go->neg_upap) {
upap_authpeer(unit);
auth |= PAP_PEER2;
  }
  if (ho->neg_chap) {
ChapAuthWithPeer(unit, user, ho->chap_mdtype);
auth |= CHAP_WITHPEER4;
  } else if (ho->neg_upap) {
if (passwd[0] == 0) {
   passwd_from_file = 1;
   if (!get_pap_passwd(passwd))
syslog(LOG_ERR3, "No secret found for PAP login");
}
upap_authwithpeer(unit, user, passwd);
auth |= PAP_WITHPEER1;
  }
  auth_pending[unit] = auth;

  if (!auth)
network_phase(unit);
290}

292/*
* Proceed to the network phase.
*/
295static void
296network_phase(unit)
  int unit;
298{
  int i;
  struct protent *protp;
  lcp_options *go = &lcp_gotoptions[unit];

  /*
   * If the peer had to authenticate, run the auth-up script now.
   */
  if ((go->neg_chap || go->neg_upap) && !did_authup) {
auth_script(_PATH_AUTHUP"/etc/ppp/auth-up");
did_authup = 1;
  }

311#ifdef CBCP_SUPPORT
  /*
   * If we negotiated callback, do it now.
   */
  if (go->neg_cbcp) {
phase = PHASE_CALLBACK5;
(*cbcp_protent.open)(unit);
return;
  }
320#endif

  phase = PHASE_NETWORK6;
323#if 0
  if (!demand)
set_filters(&pass_filter, &active_filter);
326#endif
  for (i = 0; (protp = protocols[i]) != NULL((void *)0); ++i)
      if (protp->protocol < 0xC000 && protp->enabled_flag
   && protp->open != NULL((void *)0)) {
   (*protp->open)(unit);
   if (protp->protocol != PPP_CCP0x80fd)
++num_np_open;
}

  if (num_np_open == 0)
/* nothing to do */
lcp_close(0, "No network protocols running");
338}

340/*
* The peer has failed to authenticate himself using `protocol'.
*/
343void
344auth_peer_fail(unit, protocol)
  int unit, protocol;
346{
  /*
   * Authentication failure: take the link down
   */
  lcp_close(unit, "Authentication failed");
351}

353/*
* The peer has been successfully authenticated using `protocol'.
*/
356void
357auth_peer_success(unit, protocol, name, namelen)
  int unit, protocol;
  char *name;
  int namelen;
361{
  int bit;

  switch (protocol) {
  case PPP_CHAP0xc223:
bit = CHAP_PEER8;
break;
  case PPP_PAP0xc023:
bit = PAP_PEER2;
break;
  default:
syslog(LOG_WARNING4, "auth_peer_success: unknown protocol %x",
      protocol);
return;
  }

  /*
   * Save the authenticated name of the peer for later.
   */
  if (namelen > sizeof(peer_authname) - 1)
namelen = sizeof(peer_authname) - 1;
  BCOPY(name, peer_authname, namelen)memcpy(peer_authname, name, namelen);
  peer_authname[namelen] = 0;
  script_setenv("PEERNAME", peer_authname);

  /*
   * If there is no more authentication still to be done,
   * proceed to the network (or callback) phase.
   */
  if ((auth_pending[unit] &= ~bit) == 0)
      network_phase(unit);
392}

394/*
* We have failed to authenticate ourselves to the peer using `protocol'.
*/
397void
398auth_withpeer_fail(unit, protocol)
  int unit, protocol;
400{
  if (passwd_from_file)
EXPLICIT_BZERO(passwd, MAXSECRETLEN)explicit_bzero(passwd, 256);
  /*
   * We've failed to authenticate ourselves to our peer.
   * He'll probably take the link down, and there's not much
   * we can do except wait for that.
   */
408}

410/*
* We have successfully authenticated ourselves with the peer using `protocol'.
*/
413void
414auth_withpeer_success(unit, protocol)
  int unit, protocol;
416{
  int bit;

  switch (protocol) {
  case PPP_CHAP0xc223:
bit = CHAP_WITHPEER4;
break;
  case PPP_PAP0xc023:
if (passwd_from_file)
   EXPLICIT_BZERO(passwd, MAXSECRETLEN)explicit_bzero(passwd, 256);
bit = PAP_WITHPEER1;
break;
  default:
syslog(LOG_WARNING4, "auth_peer_success: unknown protocol %x",
      protocol);
bit = 0;
  }

  /*
   * If there is no more authentication still being done,
   * proceed to the network (or callback) phase.
   */
  if ((auth_pending[unit] &= ~bit) == 0)
network_phase(unit);
440}


443/*
* np_up - a network protocol has come up.
*/
446void
447np_up(unit, proto)
  int unit, proto;
449{
  if (num_np_up == 0) {
/*
* At this point we consider that the link has come up successfully.
*/
need_holdoff = 0;

if (idle_time_limit > 0)
   TIMEOUT(check_idle, NULL, idle_time_limit)timeout((check_idle), (((void *)0)), (idle_time_limit));

/*
* Set a timeout to close the connection once the maximum
* connect time has expired.
*/
if (maxconnect > 0)
   TIMEOUT(connect_time_expired, 0, maxconnect)timeout((connect_time_expired), (0), (maxconnect));

/*
* Detach now, if the updetach option was given.
*/
if (nodetach == -1)
   detach();
  }
  ++num_np_up;
473}

475/*
* np_down - a network protocol has gone down.
*/
478void
479np_down(unit, proto)
  int unit, proto;
481{
  if (--num_np_up == 0 && idle_time_limit > 0) {
UNTIMEOUT(check_idle, NULL)untimeout((check_idle), (((void *)0)));
  }
485}

487/*
* np_finished - a network protocol has finished using the link.
*/
490void
491np_finished(unit, proto)
  int unit, proto;
493{
  if (--num_np_open <= 0) {
/* no further use for the link: shut up shop. */
lcp_close(0, "No network protocols running");
  }
498}

500/*
* check_idle - check whether the link has been idle for long
* enough that we can shut it down.
*/
504static void
505check_idle(arg)
  void *arg;
507{
  struct ppp_idle idle;
  time_t itime;

  if (!get_idle_time(0, &idle))
return;
  itime = MIN(idle.xmit_idle, idle.recv_idle)((idle.xmit_idle) < (idle.recv_idle)? (idle.xmit_idle): (idle
.recv_idle));
  if (itime >= idle_time_limit) {
/* link is idle: shut it down. */
syslog(LOG_INFO6, "Terminating connection due to lack of activity.");
lcp_close(0, "Link inactive");
  } else {
TIMEOUT(check_idle, NULL, idle_time_limit - itime)timeout((check_idle), (((void *)0)), (idle_time_limit - itime
));
  }
521}

523/*
* connect_time_expired - log a message and close the connection.
*/
526static void
527connect_time_expired(arg)
  void *arg;
529{
  syslog(LOG_INFO6, "Connect time expired");
  lcp_close(0, "Connect time expired");	/* Close connection */
532}

534/*
* auth_check_options - called to check authentication options.
*/
537void
538auth_check_options()
539{
  lcp_options *wo = &lcp_wantoptions[0];
  int can_auth;
  ipcp_options *ipwo = &ipcp_wantoptions[0];
  u_int32_t remote;

  /* Default our_name to hostname, and user to our_name */
  if (our_name[0] == 0 || usehostname)
strlcpy(our_name, hostname, HOST_NAME_MAX255+1);
  if (user[0] == 0)
strlcpy(user, our_name, MAXNAMELEN256);

  /* If authentication is required, ask peer for CHAP or PAP. */
  if (auth_required && !wo->neg_chap && !wo->neg_upap) {
wo->neg_chap = 1;
wo->neg_upap = 1;
  }

  /*
   * Check whether we have appropriate secrets to use
   * to authenticate the peer.
   */
  can_auth = wo->neg_upap && (uselogin || have_pap_secret());
  if (!can_auth && wo->neg_chap) {
remote = ipwo->accept_remote? 0: ipwo->hisaddr;
can_auth = have_chap_secret(remote_name, our_name, remote);
  }

  if (auth_required && !can_auth) {
option_error("peer authentication required but no suitable secret(s) found\n");
if (remote_name[0] == 0)
   option_error("for authenticating any peer to us (%s)\n", our_name);
else
   option_error("for authenticating peer %s to us (%s)\n",
	 remote_name, our_name);
exit(1);
  }

  /*
   * Check whether the user tried to override certain values
   * set by root.
   */
  if (!auth_required && auth_req_info.priv > 0) {
if (!default_device && devnam_info.priv == 0) {
   option_error("can't override device name when noauth option used");
   exit(1);
}
if ((connector != NULL((void *)0) && connector_info.priv == 0)
   || (disconnector != NULL((void *)0) && disconnector_info.priv == 0)
   || (welcomer != NULL((void *)0) && welcomer_info.priv == 0)) {
   option_error("can't override connect, disconnect or welcome");
   option_error("option values when noauth option used");
   exit(1);
}
  }
594}

596/*
* auth_reset - called when LCP is starting negotiations to recheck
* authentication options, i.e. whether we have appropriate secrets
* to use for authenticating ourselves and/or the peer.
*/
601void
602auth_reset(unit)
  int unit;
604{
  lcp_options *go = &lcp_gotoptions[unit];
  lcp_options *ao = &lcp_allowoptions[0];
  ipcp_options *ipwo = &ipcp_wantoptions[0];
  u_int32_t remote;

  ao->neg_upap = !refuse_pap && (passwd[0] != 0 || get_pap_passwd(NULL((void *)0)));
  ao->neg_chap = !refuse_chap
&& have_chap_secret(user, remote_name, (u_int32_t)0);

  if (go->neg_upap && !uselogin && !have_pap_secret())
go->neg_upap = 0;
  if (go->neg_chap) {
remote = ipwo->accept_remote? 0: ipwo->hisaddr;
if (!have_chap_secret(remote_name, our_name, remote))
   go->neg_chap = 0;
  }
621}


624/*
* check_passwd - Check the user name and passwd against the PAP secrets
* file.  If requested, also check against the system password database,
* and login the user if OK.
*
* returns:
*	UPAP_AUTHNAK: Authentication failed.
*	UPAP_AUTHACK: Authentication succeeded.
* In either case, msg points to an appropriate message.
*/
634int
635check_passwd(unit, auser, userlen, apasswd, passwdlen, msg, msglen)
  int unit;
  char *auser;
  int userlen;
  char *apasswd;
  int passwdlen;
  char **msg;
  int *msglen;
643{
  int ret;
  char *filename;
  FILE *f;
  struct wordlist *addrs;
  u_int32_t remote;
  ipcp_options *ipwo = &ipcp_wantoptions[unit];
  char passwd[256], user[256];
  char secret[MAXWORDLEN1024];
  static int attempts = 0;

  /*
   * Make copies of apasswd and auser, then null-terminate them.
   */
  BCOPY(apasswd, passwd, passwdlen)memcpy(passwd, apasswd, passwdlen);
  passwd[passwdlen] = '\0';
  BCOPY(auser, user, userlen)memcpy(user, auser, userlen);
  user[userlen] = '\0';
  *msg = (char *) 0;

  /*
   * Open the file of pap secrets and scan for a suitable secret
   * for authenticating this user.
   */
  filename = _PATH_UPAPFILE"/etc/ppp/pap-secrets";
  addrs = NULL((void *)0);
  ret = UPAP_AUTHACK2;
  f = fopen(filename, "r");
  if (f == NULL((void *)0)) {
1
Assuming 'f' is not equal to NULL→
2
←
Taking false branch→
syslog(LOG_ERR3, "Can't open PAP password file %s: %m", filename);
ret = UPAP_AUTHNAK3;
  } else {
check_access(f, filename);
remote = ipwo->accept_remote? 0: ipwo->hisaddr;
3
←
Assuming field 'accept_remote' is not equal to 0→
4
←
'?' condition is true→
if (scan_authfile(f, user, our_name, remote,
5
←
Assuming the condition is false→
	  secret, &addrs, filename) < 0
   || (secret[0] != 0 && (cryptpap || strcmp(passwd, secret) != 0)
6
←
Assuming the condition is false→
&& strcmp(crypt(passwd, secret), secret) != 0)) {
   syslog(LOG_WARNING4, "PAP authentication failure for %s", user);
   ret = UPAP_AUTHNAK3;
}
fclose(f);
  }

  if (uselogin && ret7.1
'ret' is equal to UPAP_AUTHACK
 == UPAP_AUTHACK2) {
7
←
Assuming 'uselogin' is not equal to 0→
8
←
Taking true branch→
ret = plogin(user, passwd, msg, msglen);
9
←
Calling 'plogin'→
if (ret == UPAP_AUTHNAK3) {
   syslog(LOG_WARNING4, "PAP login failure for %s", user);
}
  }

  if (ret == UPAP_AUTHNAK3) {
      if (*msg == (char *) 0)
   *msg = "Login incorrect";
*msglen = strlen(*msg);
/*
* Frustrate passwd stealer programs.
* Allow 10 tries, but start backing off after 3 (stolen from login).
* On 10'th, drop the connection.
*/
if (attempts++ >= 10) {
   syslog(LOG_WARNING4, "%d LOGIN FAILURES ON %s, %s",
   attempts, devnam, user);
   quit();
}
if (attempts > 3)
   sleep((u_int) (attempts - 3) * 5);
if (addrs != NULL((void *)0))
   free_wordlist(addrs);

  } else {
attempts = 0;			/* Reset count */
if (*msg == (char *) 0)
   *msg = "Login ok";
*msglen = strlen(*msg);
set_allowed_addrs(unit, addrs);
  }

  EXPLICIT_BZERO(passwd, sizeof(passwd))explicit_bzero(passwd, sizeof(passwd));
  EXPLICIT_BZERO(secret, sizeof(secret))explicit_bzero(secret, sizeof(secret));

  return ret;
725}

727/*
* plogin - Check the user name and password against the system
* password database, and login the user if OK.
*
* returns:
*	UPAP_AUTHNAK: Login failed.
*	UPAP_AUTHACK: Login succeeded.
* In either case, msg points to an appropriate message.
*/

737static int
738plogin(user, passwd, msg, msglen)
  char *user;
  char *passwd;
  char **msg;
  int *msglen;
743{
  struct passwd *pw;
  char *tty;

  pw = getpwnam_shadow(user);
10
←
Value assigned to 'pw'→
  if (crypt_checkpass(passwd, pw ? pw->pw_passwd : NULL((void *)0)))
11
←
Assuming 'pw' is null→
12
←
'?' condition is false→
13
←
Assuming the condition is false→
14
←
Taking false branch→
   return UPAP_AUTHNAK3;

  /*
   * Write a wtmp entry for this user.
   */

  tty = devnam;
  if (strncmp(tty, "/dev/", 5) == 0)
15
←
Assuming the condition is false→
16
←
Taking false branch→
tty += 5;
  logwtmp(tty, user, remote_name);		/* Add wtmp login entry */

760#if defined(_PATH_LASTLOG"/var/log/lastlog")
  {
   struct lastlog ll;
   int fd;

   if ((fd = open(_PATH_LASTLOG"/var/log/lastlog", O_RDWR0x0002)) >= 0) {
17
←
Assuming the condition is true→
18
←
Taking true branch→
memset(&ll, 0, sizeof(ll));
(void)time(&ll.ll_time);
(void)strncpy(ll.ll_line, tty, sizeof(ll.ll_line));
(void)pwrite(fd, &ll, sizeof(ll), (off_t)pw->pw_uid *
19
←
Access to field 'pw_uid' results in a dereference of a null pointer (loaded from variable 'pw')
    sizeof(ll));
(void)close(fd);
   }
  }
774#endif


  syslog(LOG_INFO6, "user %s logged in", user);
  logged_in = TRUE1;

  return (UPAP_AUTHACK2);
781}

783/*
* plogout - Logout the user.
*/
786static void
787plogout()
788{
  char *tty;

  tty = devnam;
  if (strncmp(tty, "/dev/", 5) == 0)
tty += 5;
  logwtmp(tty, "", "");		/* Wipe out utmp logout entry */

  logged_in = FALSE0;
797}


800/*
* null_login - Check if a username of "" and a password of "" are
* acceptable, and iff so, set the list of acceptable IP addresses
* and return 1.
*/
805static int
806null_login(unit)
  int unit;
808{
  char *filename;
  FILE *f;
  int i, ret;
  struct wordlist *addrs;
  char secret[MAXWORDLEN1024];

  /*
   * Open the file of pap secrets and scan for a suitable secret.
   * We don't accept a wildcard client.
   */
  filename = _PATH_UPAPFILE"/etc/ppp/pap-secrets";
  addrs = NULL((void *)0);
  f = fopen(filename, "r");
  if (f == NULL((void *)0))
return 0;
  check_access(f, filename);

  i = scan_authfile(f, "", our_name, (u_int32_t)0, secret, &addrs, filename);
  ret = i >= 0 && (i & NONWILD_CLIENT2) != 0 && secret[0] == 0;
  EXPLICIT_BZERO(secret, sizeof(secret))explicit_bzero(secret, sizeof(secret));

  if (ret)
set_allowed_addrs(unit, addrs);
  else
free_wordlist(addrs);

  fclose(f);
  return ret;
837}


840/*
* get_pap_passwd - get a password for authenticating ourselves with
* our peer using PAP.  Returns 1 on success, 0 if no suitable password
* could be found.
*/
845static int
846get_pap_passwd(passwd)
  char *passwd;
848{
  char *filename;
  FILE *f;
  int ret;
  char secret[MAXWORDLEN1024];

  filename = _PATH_UPAPFILE"/etc/ppp/pap-secrets";
  f = fopen(filename, "r");
  if (f == NULL((void *)0))
return 0;
  check_access(f, filename);
  ret = scan_authfile(f, user,
	remote_name[0]? remote_name: NULL((void *)0),
	(u_int32_t)0, secret, NULL((void *)0), filename);
  fclose(f);
  if (ret < 0)
return 0;
  if (passwd != NULL((void *)0))
strlcpy(passwd, secret, MAXSECRETLEN256);
  EXPLICIT_BZERO(secret, sizeof(secret))explicit_bzero(secret, sizeof(secret));
  return 1;
869}


872/*
* have_pap_secret - check whether we have a PAP file with any
* secrets that we could possibly use for authenticating the peer.
*/
876static int
877have_pap_secret()
878{
  FILE *f;
  int ret;
  char *filename;
  ipcp_options *ipwo = &ipcp_wantoptions[0];
  u_int32_t remote;

  filename = _PATH_UPAPFILE"/etc/ppp/pap-secrets";
  f = fopen(filename, "r");
  if (f == NULL((void *)0))
return 0;

  remote = ipwo->accept_remote? 0: ipwo->hisaddr;
  ret = scan_authfile(f, NULL((void *)0), our_name, remote, NULL((void *)0), NULL((void *)0), filename);
  fclose(f);
  if (ret < 0)
return 0;

  return 1;
897}


900/*
* have_chap_secret - check whether we have a CHAP file with a
* secret that we could possibly use for authenticating `client'
* on `server'.  Either can be the null string, meaning we don't
* know the identity yet.
*/
906static int
907have_chap_secret(client, server, remote)
  char *client;
  char *server;
  u_int32_t remote;
911{
  FILE *f;
  int ret;
  char *filename;

  filename = _PATH_CHAPFILE"/etc/ppp/chap-secrets";
  f = fopen(filename, "r");
  if (f == NULL((void *)0))
return 0;

  if (client[0] == 0)
client = NULL((void *)0);
  else if (server[0] == 0)
server = NULL((void *)0);

  ret = scan_authfile(f, client, server, remote, NULL((void *)0), NULL((void *)0), filename);
  fclose(f);
  if (ret < 0)
return 0;

  return 1;
932}


935/*
* get_secret - open the CHAP secret file and return the secret
* for authenticating the given client on the given server.
* (We could be either client or server).
*/
940int
941get_secret(unit, client, server, secret, secret_len, save_addrs)
  int unit;
  char *client;
  char *server;
  char *secret;
  int *secret_len;
  int save_addrs;
948{
  FILE *f;
  int ret, len;
  char *filename;
  struct wordlist *addrs;
  char secbuf[MAXWORDLEN1024];

  filename = _PATH_CHAPFILE"/etc/ppp/chap-secrets";
  addrs = NULL((void *)0);
  secbuf[0] = 0;

  f = fopen(filename, "r");
  if (f == NULL((void *)0)) {
syslog(LOG_ERR3, "Can't open chap secret file %s: %m", filename);
return 0;
  }
  check_access(f, filename);

  ret = scan_authfile(f, client, server, (u_int32_t)0,
	secbuf, &addrs, filename);
  fclose(f);
  if (ret < 0)
return 0;

  if (save_addrs)
set_allowed_addrs(unit, addrs);

  len = strlen(secbuf);
  if (len > MAXSECRETLEN256) {
syslog(LOG_ERR3, "Secret for %s on %s is too long", client, server);
len = MAXSECRETLEN256;
  }
  BCOPY(secbuf, secret, len)memcpy(secret, secbuf, len);
  EXPLICIT_BZERO(secbuf, sizeof(secbuf))explicit_bzero(secbuf, sizeof(secbuf));
  *secret_len = len;

  return 1;
985}

987/*
* set_allowed_addrs() - set the list of allowed addresses.
*/
990static void
991set_allowed_addrs(unit, addrs)
  int unit;
  struct wordlist *addrs;
994{
  if (addresses[unit] != NULL((void *)0))
free_wordlist(addresses[unit]);
  addresses[unit] = addrs;

  /*
   * If there's only one authorized address we might as well
   * ask our peer for that one right away
   */
  if (addrs != NULL((void *)0) && addrs->next == NULL((void *)0)) {
char *p = addrs->word;
struct ipcp_options *wo = &ipcp_wantoptions[unit];
struct in_addr ina;
struct hostent *hp;

if (*p != '!' && *p != '-' && !ISWILD(p)(p[0] == '*' && p[1] == 0) && strchr(p, '/') == NULL((void *)0)) {
   hp = gethostbyname(p);
   if (hp != NULL((void *)0) && hp->h_addrtype == AF_INET2)
wo->hisaddr = *(u_int32_t *)hp->h_addrh_addr_list[0];
   else if (inet_aton(p, &ina) == 1)
wo->hisaddr = ina.s_addr;
}
  }
1017}

1019/*
* auth_ip_addr - check whether the peer is authorized to use
* a given IP address.  Returns 1 if authorized, 0 otherwise.
*/
1023int
1024auth_ip_addr(unit, addr)
  int unit;
  u_int32_t addr;
1027{
  return ip_addr_check(addr, addresses[unit]);
1029}

1031static int
1032ip_addr_check(addr, addrs)
  u_int32_t addr;
  struct wordlist *addrs;
1035{
  u_int32_t mask, ah;
  struct in_addr ina;
  int accept, r = 1;
  char *ptr_word, *ptr_mask;
  struct hostent *hp;

  /* don't allow loopback or multicast address */
  if (bad_ip_adrs(addr))
return 0;

  if (addrs == NULL((void *)0))
return !auth_required;		/* no addresses authorized */

  for (; addrs != NULL((void *)0); addrs = addrs->next) {
/* "-" means no addresses authorized, "*" means any address allowed */
ptr_word = addrs->word;
if (strcmp(ptr_word, "-") == 0)
   break;
if (strcmp(ptr_word, "*") == 0)
   return 1;

accept = 1;
if (*ptr_word == '!') {
   accept = 0;
   ++ptr_word;
}

mask = ~ (u_int32_t) 0;
ptr_mask = strchr (ptr_word, '/');
if (ptr_mask != NULL((void *)0)) {
   int bit_count;

   bit_count = (int) strtol (ptr_mask+1, (char **) 0, 10);
   if (bit_count <= 0 || bit_count > 32) {
syslog (LOG_WARNING4,
	"invalid address length %s in auth. address list",
	ptr_mask);
continue;
   }
   *ptr_mask = '\0';
   mask <<= 32 - bit_count;
}

hp = gethostbyname(ptr_word);
if (hp != NULL((void *)0) && hp->h_addrtype == AF_INET2) {
   ina.s_addr = *(u_int32_t *)hp->h_addrh_addr_list[0];
} else {
   r = inet_aton (ptr_word, &ina);
   if (ptr_mask == NULL((void *)0)) {
/* calculate appropriate mask for net */
ah = ntohl(ina.s_addr)(__uint32_t)(__builtin_constant_p(ina.s_addr) ? (__uint32_t)(
((__uint32_t)(ina.s_addr) & 0xff) << 24 | ((__uint32_t
)(ina.s_addr) & 0xff00) << 8 | ((__uint32_t)(ina.s_addr
) & 0xff0000) >> 8 | ((__uint32_t)(ina.s_addr) &
 0xff000000) >> 24) : __swap32md(ina.s_addr));
if (IN_CLASSA(ah)(((u_int32_t)(ah) & ((u_int32_t)(0x80000000))) == ((u_int32_t
)(0x00000000))))
    mask = IN_CLASSA_NET((u_int32_t)(0xff000000));
else if (IN_CLASSB(ah)(((u_int32_t)(ah) & ((u_int32_t)(0xc0000000))) == ((u_int32_t
)(0x80000000))))
    mask = IN_CLASSB_NET((u_int32_t)(0xffff0000));
else if (IN_CLASSC(ah)(((u_int32_t)(ah) & ((u_int32_t)(0xe0000000))) == ((u_int32_t
)(0xc0000000))))
    mask = IN_CLASSC_NET((u_int32_t)(0xffffff00));
   }
}

if (ptr_mask != NULL((void *)0))
   *ptr_mask = '/';

if (r == 0)
   syslog (LOG_WARNING4,
    "unknown host %s in auth. address list",
    addrs->word);
else
   /* Here ina.s_addr and addr are in network byte order,
      and mask is in host order. */
   if (((addr ^ ina.s_addr) & htonl(mask)(__uint32_t)(__builtin_constant_p(mask) ? (__uint32_t)(((__uint32_t
)(mask) & 0xff) << 24 | ((__uint32_t)(mask) & 0xff00
) << 8 | ((__uint32_t)(mask) & 0xff0000) >> 8
 | ((__uint32_t)(mask) & 0xff000000) >> 24) : __swap32md
(mask))) == 0)
return accept;
  }
  return 0;			/* not in list => can't have it */
1110}

1112/*
* bad_ip_adrs - return 1 if the IP address is one we don't want
* to use, such as an address in the loopback net or a multicast address.
* addr is in network byte order.
*/
1117int
1118bad_ip_adrs(addr)
  u_int32_t addr;
1120{
  addr = ntohl(addr)(__uint32_t)(__builtin_constant_p(addr) ? (__uint32_t)(((__uint32_t
)(addr) & 0xff) << 24 | ((__uint32_t)(addr) & 0xff00
) << 8 | ((__uint32_t)(addr) & 0xff0000) >> 8
 | ((__uint32_t)(addr) & 0xff000000) >> 24) : __swap32md
(addr));
  return (addr >> IN_CLASSA_NSHIFT24) == IN_LOOPBACKNET127
|| IN_MULTICAST(addr)(((u_int32_t)(addr) & ((u_int32_t)(0xf0000000))) == ((u_int32_t
)(0xe0000000)));
1124}

1126/*
* check_access - complain if a secret file has too-liberal permissions.
*/
1129void
1130check_access(f, filename)
  FILE *f;
  char *filename;
1133{
  struct stat sbuf;

  if (fstat(fileno(f)(!__isthreaded ? ((f)->_file) : (fileno)(f)), &sbuf) < 0) {
syslog(LOG_WARNING4, "cannot stat secret file %s: %m", filename);
  } else if ((sbuf.st_mode & (S_IRWXG0000070 | S_IRWXO0000007)) != 0) {
syslog(LOG_WARNING4, "Warning - secret file %s has world and/or group access", filename);
  }
1141}


1144/*
* scan_authfile - Scan an authorization file for a secret suitable
* for authenticating `client' on `server'.  The return value is -1
* if no secret is found, otherwise >= 0.  The return value has
* NONWILD_CLIENT set if the secret didn't have "*" for the client, and
* NONWILD_SERVER set if the secret didn't have "*" for the server.
* Any following words on the line (i.e. address authorization
* info) are placed in a wordlist and returned in *addrs.
*/
1153static int
1154scan_authfile(f, client, server, ipaddr, secret, addrs, filename)
  FILE *f;
  char *client;
  char *server;
  u_int32_t ipaddr;
  char *secret;
  struct wordlist **addrs;
  char *filename;
1162{
  int newline, xxx;
  int got_flag, best_flag;
  FILE *sf;
  struct wordlist *ap, *addr_list, *alist, *alast;
  char word[MAXWORDLEN1024];
  char atfile[MAXWORDLEN1024];
  char lsecret[MAXWORDLEN1024];

  if (addrs != NULL((void *)0))
*addrs = NULL((void *)0);
  addr_list = NULL((void *)0);
  if (!getword(f, word, &newline, filename))
return -1;		/* file is empty??? */
  newline = 1;
  best_flag = -1;
  for (;;) {
/*
* Skip until we find a word at the start of a line.
*/
while (!newline && getword(f, word, &newline, filename))
   ;
if (!newline)
   break;		/* got to end of file */

/*
* Got a client - check if it's a match or a wildcard.
*/
got_flag = 0;
if (client != NULL((void *)0) && strcmp(word, client) != 0 && !ISWILD(word)(word[0] == '*' && word[1] == 0)) {
   newline = 0;
   continue;
}
if (!ISWILD(word)(word[0] == '*' && word[1] == 0))
   got_flag = NONWILD_CLIENT2;

/*
* Now get a server and check if it matches.
*/
if (!getword(f, word, &newline, filename))
   break;
if (newline)
   continue;
if (server != NULL((void *)0) && strcmp(word, server) != 0 && !ISWILD(word)(word[0] == '*' && word[1] == 0))
   continue;
if (!ISWILD(word)(word[0] == '*' && word[1] == 0))
   got_flag |= NONWILD_SERVER1;

/*
* Got some sort of a match - see if it's better than what
* we have already.
*/
if (got_flag <= best_flag)
   continue;

/*
* Get the secret.
*/
if (!getword(f, word, &newline, filename))
   break;
if (newline)
   continue;

/*
* Special syntax: @filename means read secret from file.
*/
if (word[0] == '@') {
   strlcpy(atfile, word+1, sizeof atfile);
   if ((sf = fopen(atfile, "r")) == NULL((void *)0)) {
syslog(LOG_WARNING4, "can't open indirect secret file %s",
       atfile);
continue;
   }
   check_access(sf, atfile);
   if (!getword(sf, word, &xxx, atfile)) {
syslog(LOG_WARNING4, "no secret in indirect secret file %s",
       atfile);
fclose(sf);
continue;
   }
   fclose(sf);
}
if (secret != NULL((void *)0))
   strlcpy(lsecret, word, sizeof lsecret);

/*
* Now read address authorization info and make a wordlist.
*/
alist = alast = NULL((void *)0);
for (;;) {
   size_t wordlen;

   if (!getword(f, word, &newline, filename) || newline)
break;
   wordlen = strlen(word);	/* NUL in struct wordlist */
   ap = (struct wordlist *) malloc(sizeof(struct wordlist) +
wordlen);

   if (ap == NULL((void *)0))
novm("authorized addresses");
   ap->next = NULL((void *)0);
   strlcpy(ap->word, word, wordlen + 1);
   if (alist == NULL((void *)0))
alist = ap;
   else
alast->next = ap;
   alast = ap;
}

/*
* Check if the given IP address is allowed by the wordlist.
*/
if (ipaddr != 0 && !ip_addr_check(ipaddr, alist)) {
   free_wordlist(alist);
   continue;
}

/*
* This is the best so far; remember it.
*/
best_flag = got_flag;
if (addr_list)
   free_wordlist(addr_list);
addr_list = alist;
if (secret != NULL((void *)0))
   strlcpy(secret, lsecret, MAXWORDLEN1024);

if (!newline)
   break;
  }

  if (addrs != NULL((void *)0))
*addrs = addr_list;
  else if (addr_list != NULL((void *)0))
free_wordlist(addr_list);

  return best_flag;
1299}

1301/*
* free_wordlist - release memory allocated for a wordlist.
*/
1304static void
1305free_wordlist(wp)
  struct wordlist *wp;
1307{
  struct wordlist *next;

  while (wp != NULL((void *)0)) {
next = wp->next;
free(wp);
wp = next;
  }
1315}

1317/*
* auth_script - execute a script with arguments
* interface-name peer-name real-user tty speed
*/
1321static void
1322auth_script(script)
  char *script;
1324{
  char strspeed[32];
  struct passwd *pw;
  char struid[32];
  char *user_name;
  char *argv[8];

  if ((pw = getpwuid(getuid())) != NULL((void *)0) && pw->pw_name != NULL((void *)0))
user_name = pw->pw_name;
  else {
snprintf(struid, sizeof struid, "%u", getuid());
user_name = struid;
  }
  snprintf(strspeed, sizeof strspeed, "%d", baud_rate);

  argv[0] = script;
  argv[1] = ifname;
  argv[2] = peer_authname;
  argv[3] = user_name;
  argv[4] = devnam;
  argv[5] = strspeed;
  argv[6] = NULL((void *)0);

  run_program(script, argv, 0);
1348}