inetutils/libinetutils/kcmd.c

/*
  Copyright (C) 1997-2025 Free Software Foundation, Inc.

  This file is part of GNU Inetutils.

  GNU Inetutils 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 3 of the License, or (at
  your option) any later version.

  GNU Inetutils is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see `http://www.gnu.org/licenses/'. */

/*
 * Copyright (c) 1983, 1993
 *	The Regents of the University of California.  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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <config.h>

#if defined KRB5 || defined SHISHI

# include <sys/param.h>
# include <sys/file.h>
# include <sys/socket.h>
# include <sys/stat.h>
# include <fcntl.h>

# include <netinet/in.h>
# include <arpa/inet.h>

# if defined KRB5
#  ifdef HAVE_KRB5_H
#   include <krb5.h>
#  endif
#  include "kerberos5_def.h"
# elif defined(SHISHI)		/* !KRB5 */
#  include <shishi.h>
#  include "shishi_def.h"
# endif/* SHISHI && !KRB5 */

# include <ctype.h>
# include <errno.h>
# include <netdb.h>
# include <pwd.h>
# include <signal.h>
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
# include <unistd.h>

# ifndef MAXHOSTNAMELEN
#  define MAXHOSTNAMELEN 64
# endif

# define START_PORT	5120	/* arbitrary */

int getport (int *, int);

# if defined KRB5
int
kcmd (krb5_context *ctx, int *sock, char **ahost, unsigned short rport,
      char *locuser, char **remuser, char *cmd, int *fd2p,
      char *service, const char *realm, krb5_keyblock **key,
      struct sockaddr_in *laddr, struct sockaddr_in *faddr, long authopts)
# elif defined(SHISHI)		/* !KRB5 */
int
kcmd (Shishi **h, int *sock, char **ahost, unsigned short rport,
      char *locuser, char **remuser, char *cmd, int *fd2p,
      char *service, const char *realm, Shishi_key **key,
      struct sockaddr_storage *laddr, struct sockaddr_storage *faddr,
      long authopts, int af)
# endif				/* SHISHI && !KRB5 */
{
  int s, timo = 1, pid;
# ifdef HAVE_SIGACTION
  sigset_t sigs, osigs;
# else
  long oldmask;
# endif/* !HAVE_SIGACTION */
  struct sockaddr_storage sin, from;
  socklen_t len;
  char c;

# ifdef ATHENA_COMPAT
  int lport = IPPORT_RESERVED - 1;
# else
  int lport = START_PORT;
# endif
# if HAVE_DECL_GETADDRINFO
  struct addrinfo hints, *ai, *res;
  char portstr[8], fqdn[NI_MAXHOST];
# else/* !HAVE_DECL_GETADDRINFO */
  struct hostent *hp;
# endif
  int rc;
  char *host_save, *host;
  int status;

  pid = getpid ();

  /* Extract Kerberos instance name.  */
  host = strchr (*ahost, '/');
  if (host)
    ++host;
  else
    host = *ahost;

# if HAVE_DECL_GETADDRINFO
  memset (&hints, 0, sizeof (hints));
#  ifdef KRB5
  hints.ai_family = AF_INET;
#  else
  /* SHISHI && !KRB5 */
  hints.ai_family = af;
#  endif
  hints.ai_socktype = SOCK_STREAM;
  hints.ai_flags = AI_CANONNAME;
  snprintf (portstr, sizeof (portstr), "%hu", ntohs (rport));

  rc = getaddrinfo (host, portstr, &hints, &res);
  if (rc)
    {
      fprintf (stderr, "kcmd: host %s: %s\n", host, gai_strerror (rc));
      return (-1);
    }

  ai = res;

  /* Attempt back resolving into the official host name.  */
  rc = getnameinfo (ai->ai_addr, ai->ai_addrlen, fqdn, sizeof (fqdn),
		    NULL, 0, NI_NAMEREQD);
  if (!rc)
    {
      host_save = malloc (strlen (fqdn) + 1);
      if (host_save == NULL)
	return (-1);
      strcpy (host_save, fqdn);
    }
  else
    {
      host_save = malloc (strlen (ai->ai_canonname) + 1);
      if (host_save == NULL)
	return (-1);
      strcpy (host_save, ai->ai_canonname);
    }

# else/* !HAVE_DECL_GETADDRINFO */
  /* Often the following rejects non-IPv4.
   * This is dependent on system implementation.  */
  hp = gethostbyname (host);
  if (hp == NULL)
    {
      /* fprintf(stderr, "%s: unknown host\n", host); */
      return (-1);
    }

  host_save = malloc (strlen (hp->h_name) + 1);
  if (host_save == NULL)
    return -1;
  strcpy (host_save, hp->h_name);
# endif/* !HAVE_DECL_GETADDRINFO */

  if (host == *ahost)
    *ahost = host_save;		/* Simple host name string.  */
  else
    {
      /* Server name `*ahost' is a Kerberized name.  */
      char *p;

      p = malloc ((host - *ahost) + strlen (host_save) + 1);
      if (p == NULL)
	return (-1);

      /* Extract prefix from `*ahost', excluding slash,
       * and concatenate the host's canonical name, but
       * preceded by a slash.
       */
      sprintf (p, "%.*s/%s", (int) (host - *ahost - 1), *ahost, host_save);
      *ahost = p;
    }

# ifdef HAVE_SIGACTION
  sigemptyset (&sigs);
  sigaddset (&sigs, SIGURG);
  sigprocmask (SIG_BLOCK, &sigs, &osigs);
# else
  oldmask = sigblock (sigmask (SIGURG));
# endif/* !HAVE_SIGACTION */
  for (;;)
    {
# if HAVE_DECL_GETADDRINFO
      s = getport (&lport, ai->ai_family);
# else/* !HAVE_DECL_GETADDRINFO */
      s = getport (&lport, hp->h_addrtype);
# endif
      if (s < 0)
	{
	  if (errno == EAGAIN)
	    fprintf (stderr, "kcmd(socket): All ports in use\n");
	  else
	    perror ("kcmd: socket");
# if HAVE_SIGACTION
	  sigprocmask (SIG_SETMASK, &osigs, NULL);
# else
	  sigsetmask (oldmask);
# endif/* !HAVE_SIGACTION */
	  return (-1);
	}
      fcntl (s, F_SETOWN, pid);

# if HAVE_DECL_GETADDRINFO
      len = ai->ai_addrlen;
      memcpy (&sin, ai->ai_addr, ai->ai_addrlen);
# else/* !HAVE_DECL_GETADDRINFO */
      sin.ss_family = hp->h_addrtype;
      switch (hp->h_addrtype)
	{
	case AF_INET6:
	  len = sizeof (struct sockaddr_in6);
#  ifdef HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN
	  sin.ss_len = len;
#  endif
	  memcpy (&((struct sockaddr_in6 *) &sin)->sin6_addr,
		  hp->h_addr, hp->h_length);
	  ((struct sockaddr_in6 *) &sin)->sin6_port = rport;
	  break;
	case AF_INET:
	default:
	  len = sizeof (struct sockaddr_in);
#  ifdef HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN
	  sin.ss_len = len;
#  endif
	  memcpy (&((struct sockaddr_in *) &sin)->sin_addr,
		  hp->h_addr, hp->h_length);
	  ((struct sockaddr_in *) &sin)->sin_port = rport;
	}
# endif/* !HAVE_DECL_GETADDRINFO */

      if (connect (s, (struct sockaddr *) &sin, len) >= 0)
	break;
      close (s);
      if (errno == EADDRINUSE)
	{
	  lport--;
	  continue;
	}
      /*
       * don't wait very long for Kerberos rcmd.
       */
      if (errno == ECONNREFUSED && timo <= 4)
	{
	  /* sleep(timo); don't wait at all here */
	  timo *= 2;
	  continue;
	}
# if ! defined ultrix || defined sun
#  if HAVE_DECL_GETADDRINFO
      if (ai->ai_next)
#  else
      /* !HAVE_DECL_GETADDRINFO */
      if (hp->h_addr_list[1] != NULL)
#  endif
	{
	  int oerrno = errno;
	  char addrstr[INET6_ADDRSTRLEN];

#  if HAVE_DECL_GETADDRINFO
	  getnameinfo (ai->ai_addr, ai->ai_addrlen,
		       addrstr, sizeof (addrstr), NULL, 0, NI_NUMERICHOST);
	  fprintf (stderr, "kcmd: connect to address %s: ", addrstr);
	  errno = oerrno;
	  perror (NULL);
	  ai = ai->ai_next;
	  getnameinfo (ai->ai_addr, ai->ai_addrlen,
		       addrstr, sizeof (addrstr), NULL, 0, NI_NUMERICHOST);
	  fprintf (stderr, "Trying %s...\n", addrstr);
#  else
	  /* !HAVE_DECL_GETADDRINFO */
	  fprintf (stderr, "kcmd: connect to address %s: ",
		   inet_ntop (hp->h_addrtype, hp->h_addr_list[0],
			      addrstr, sizeof (addrstr)));
	  errno = oerrno;
	  perror (NULL);
	  hp->h_addr_list++;
	  fprintf (stderr, "Trying %s...\n",
		   inet_ntop (hp->h_addrtype, hp->h_addr_list[0],
			      addrstr, sizeof (addrstr)));
#  endif
	  /* !HAVE_DECL_GETADDRINFO */
	  continue;
	}
# endif/* !(defined(ultrix) || defined(sun)) */
# if HAVE_DECL_GETADDRINFO
      if (errno != ECONNREFUSED)
	perror (res->ai_canonname);

      if (res)
	freeaddrinfo (res);
# else/* !HAVE_DECL_GETADDRINFO */
      if (errno != ECONNREFUSED)
	perror (hp->h_name);
# endif

# if HAVE_SIGACTION
      sigprocmask (SIG_SETMASK, &osigs, NULL);
# else
      sigsetmask (oldmask);
# endif/* !HAVE_SIGACTION */

      return (-1);
    }
# if HAVE_DECL_GETADDRINFO
  if (res)
    freeaddrinfo (res);
# endif

  lport--;
  if (fd2p == 0)
    {
      write (s, "", 1);
      lport = 0;
    }
  else
    {
      char num[8];
      int port, s2, s3;

      s2 = getport (&lport, sin.ss_family);
      len = sizeof (from);

      if (s2 < 0)
	{
	  status = -1;
	  goto bad;
	}
      listen (s2, 1);
      sprintf (num, "%d", lport);
      if (write (s, num, strlen (num) + 1) != (ssize_t) strlen (num) + 1)
	{
	  perror ("kcmd(write): setting up stderr");
	  close (s2);
	  status = -1;
	  goto bad;
	}
      s3 = accept (s2, (struct sockaddr *) &from, &len);
      close (s2);
      if (s3 < 0)
	{
	  perror ("kcmd:accept");
	  lport = 0;
	  status = -1;
	  goto bad;
	}
      *fd2p = s3;
      port = (from.ss_family == AF_INET6)
	? ntohs (((struct sockaddr_in6 *) &from)->sin6_port)
	: ntohs (((struct sockaddr_in *) &from)->sin_port);

      if (port >= IPPORT_RESERVED
	  || (from.ss_family != AF_INET && from.ss_family != AF_INET6))
	{
	  fprintf (stderr,
		   "kcmd(socket): protocol failure in circuit setup.\n");
	  status = -1;
	  goto bad2;
	}
    }
  /*
   * Kerberos-authenticated service.  Don't have to send locuser,
   * since its already in the ticket, and we'll extract it on
   * the other side.
   */
  /* write(s, locuser, strlen(locuser)+1); */

  /* set up the needed stuff for mutual auth, but only if necessary */
# ifdef KRB5
  if (authopts & AP_OPTS_MUTUAL_REQUIRED)
# elif defined(SHISHI)		/* !KRB5 */
  if (authopts & SHISHI_APOPTIONS_MUTUAL_REQUIRED)
# endif
    {
      socklen_t sin_len;

      memcpy (faddr, &sin, sizeof (*faddr));

      sin_len = sizeof (*laddr);
      if (getsockname (s, (struct sockaddr *) laddr, &sin_len) < 0)
	{
	  perror ("kcmd(getsockname)");
	  status = -1;
	  goto bad2;
	}
    }

  (void) service;		/* Silence warning.  XXX: Implicit use?  */

# ifdef KRB5
  status = kerberos_auth (ctx, 0, remuser, *ahost, s, cmd, rport, key, realm);
  if (status != 0)
    goto bad2;

# elif defined(SHISHI)		/* !KRB5 */
  status = shishi_auth (h, 0, remuser, *ahost, s, cmd, rport, key, realm);
  if (status != SHISHI_OK)
    goto bad2;

# endif/* SHISHI && !KRB5 */

  write (s, *remuser, strlen (*remuser) + 1);

  write (s, cmd, strlen (cmd) + 1);

  if (locuser && locuser[0])
    write (s, locuser, strlen (locuser) + 1);
  else
    write (s, *remuser, strlen (*remuser) + 1);

  {
    int zero = 0;		/* No forwarding of credentials.  */

    write (s, &zero, sizeof (zero));
  }

  rc = read (s, &c, sizeof (c));
  if (rc != sizeof (c))
    {
      if (rc == -1)
	perror (*ahost);
      else
	fprintf (stderr, "kcmd: bad connection with remote host\n");
      status = -1;
      goto bad2;
    }
  if (c != '\0')
    {
      while (read (s, &c, 1) == 1)
	{
	  write (2, &c, 1);
	  if (c == '\n')
	    break;
	}
      status = -1;
      errno = ENOENT;
      goto bad2;
    }
# if HAVE_SIGACTION
  sigprocmask (SIG_SETMASK, &osigs, NULL);
# else
  sigsetmask (oldmask);
# endif/* !HAVE_SIGACTION */
  *sock = s;
# if defined KRB5
  return (0);
# elif defined(SHISHI)		/* !KRB5 */
  return (SHISHI_OK);
# endif/* SHISHI && !KRB5 */
bad2:
  if (lport)
    close (*fd2p);
bad:
  close (s);
# if HAVE_SIGACTION
  sigprocmask (SIG_SETMASK, &osigs, NULL);
# else
  sigsetmask (oldmask);
# endif/* !HAVE_SIGACTION */
  return (status);
}

int
getport (int *alport, int af)
{
  struct sockaddr_storage sin;
  socklen_t len;
  int s;

  memset (&sin, 0, sizeof (sin));
  sin.ss_family = af;
  len = (af == AF_INET6) ? sizeof (struct sockaddr_in6)
    : sizeof (struct sockaddr_in);
# ifdef HAVE_STRUCT_SOCKADDR_STORAGE_SS_LEN
  sin.ss_len = len;
# endif

  s = socket (sin.ss_family, SOCK_STREAM, 0);
  if (s < 0)
    return (-1);
  for (;;)
    {
      switch (af)
	{
	case AF_INET6:
	  ((struct sockaddr_in6 *) &sin)->sin6_port =
	    htons ((unsigned short) *alport);
	  break;
	case AF_INET:
	default:
	  ((struct sockaddr_in *) &sin)->sin_port =
	    htons ((unsigned short) *alport);
	}

      if (bind (s, (struct sockaddr *) &sin, len) >= 0)
	return (s);
      if (errno != EADDRINUSE)
	{
	  close (s);
	  return (-1);
	}
      (*alport)--;
# ifdef ATHENA_COMPAT
      if (*alport == IPPORT_RESERVED / 2)
	{
# else
      if (*alport == IPPORT_RESERVED)
	{
# endif
	  close (s);
	  errno = EAGAIN;	/* close */
	  return (-1);
	}
    }
}

#endif /* KRB5 || SHISHI */