text: /* $OpenBSD: auth-krb5.c,v 1.21 2016/01/27 06:44:58 djm Exp $ */
  /*
   *    Kerberos v5 authentication and ticket-passing routines.
   *
   * From: FreeBSD: src/crypto/openssh/auth-krb5.c,v 1.6 2001/02/13 16:58:04 assar
   */
  /*
   * Copyright (c) 2002 Daniel Kouril.  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.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 "includes.h"
  
  #include <sys/types.h>
  #include <pwd.h>
  #include <stdarg.h>
  
  #include "xmalloc.h"
  #include "ssh.h"
  #include "ssh1.h"
  #include "packet.h"
  #include "log.h"
  #include "buffer.h"
  #include "misc.h"
  #include "servconf.h"
  #include "uidswap.h"
  #include "key.h"
  #include "hostfile.h"
  #include "auth.h"
  
  #ifdef KRB5
  #include <errno.h>
  #include <unistd.h>
  #include <string.h>
  #include <krb5.h>
  
  extern ServerOptions	 options;
  
  static int
  krb5_init(void *context)
  {
  	Authctxt *authctxt = (Authctxt *)context;
  	krb5_error_code problem;
  
  	if (authctxt->krb5_ctx == NULL) {
  		problem = krb5_init_context(&authctxt->krb5_ctx);
  		if (problem)
  			return (problem);
  	}
  	return (0);
  }
  
  int
  auth_krb5_password(Authctxt *authctxt, const char *password)
  {
  #ifndef HEIMDAL
  	krb5_creds creds;
  	krb5_principal server;
  #endif
  	krb5_error_code problem;
  	krb5_ccache ccache = NULL;
  	int len;
  	char *client, *platform_client;
  	const char *errmsg;
  
  	/* get platform-specific kerberos client principal name (if it exists) */
  	platform_client = platform_krb5_get_principal_name(authctxt->pw->pw_name);
  	client = platform_client ? platform_client : authctxt->pw->pw_name;
  
  	temporarily_use_uid(authctxt->pw);
  
  	problem = krb5_init(authctxt);
  	if (problem)
  		goto out;
  
  	problem = krb5_parse_name(authctxt->krb5_ctx, client,
  		    &authctxt->krb5_user);
  	if (problem)
  		goto out;
  
  #ifdef HEIMDAL
  # ifdef HAVE_KRB5_CC_NEW_UNIQUE
  	problem = krb5_cc_new_unique(authctxt->krb5_ctx,
  	     krb5_mcc_ops.prefix, NULL, &ccache);
  # else
  	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_mcc_ops, &ccache);
  # endif
  	if (problem)
  		goto out;
  
  	problem = krb5_cc_initialize(authctxt->krb5_ctx, ccache,
  		authctxt->krb5_user);
  	if (problem)
  		goto out;
  
  	restore_uid();
  
  	problem = krb5_verify_user(authctxt->krb5_ctx, authctxt->krb5_user,
  	    ccache, password, 1, NULL);
  
  	temporarily_use_uid(authctxt->pw);
  
  	if (problem)
  		goto out;
  
  # ifdef HAVE_KRB5_CC_NEW_UNIQUE
  	problem = krb5_cc_new_unique(authctxt->krb5_ctx,
  	     krb5_fcc_ops.prefix, NULL, &authctxt->krb5_fwd_ccache);
  # else
  	problem = krb5_cc_gen_new(authctxt->krb5_ctx, &krb5_fcc_ops,
  	    &authctxt->krb5_fwd_ccache);
  # endif
  	if (problem)
  		goto out;
  
  	problem = krb5_cc_copy_cache(authctxt->krb5_ctx, ccache,
  	    authctxt->krb5_fwd_ccache);
  	krb5_cc_destroy(authctxt->krb5_ctx, ccache);
  	ccache = NULL;
  	if (problem)
  		goto out;
  
  #else
  	problem = krb5_get_init_creds_password(authctxt->krb5_ctx, &creds,
  	    authctxt->krb5_user, (char *)password, NULL, NULL, 0, NULL, NULL);
  	if (problem)
  		goto out;
  
  	problem = krb5_sname_to_principal(authctxt->krb5_ctx, NULL, NULL,
  	    KRB5_NT_SRV_HST, &server);
  	if (problem)
  		goto out;
  
  	restore_uid();
  	problem = krb5_verify_init_creds(authctxt->krb5_ctx, &creds, server,
  	    NULL, NULL, NULL);
  	krb5_free_principal(authctxt->krb5_ctx, server);
  	temporarily_use_uid(authctxt->pw);
  	if (problem)
  		goto out;
  
  	if (!krb5_kuserok(authctxt->krb5_ctx, authctxt->krb5_user,
  	    authctxt->pw->pw_name)) {
  		problem = -1;
  		goto out;
  	}
  
  	problem = ssh_krb5_cc_gen(authctxt->krb5_ctx, &authctxt->krb5_fwd_ccache);
  	if (problem)
  		goto out;
  
  	problem = krb5_cc_initialize(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
  				     authctxt->krb5_user);
  	if (problem)
  		goto out;
  
  	problem= krb5_cc_store_cred(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache,
  				 &creds);
  	if (problem)
  		goto out;
  #endif
  
  	authctxt->krb5_ticket_file = (char *)krb5_cc_get_name(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
  
  	len = strlen(authctxt->krb5_ticket_file) + 6;
  	authctxt->krb5_ccname = xmalloc(len);
  	snprintf(authctxt->krb5_ccname, len, "FILE:%s",
  	    authctxt->krb5_ticket_file);
  
  #ifdef USE_PAM
  	if (options.use_pam)
  		do_pam_putenv("KRB5CCNAME", authctxt->krb5_ccname);
  #endif
  
   out:
  	restore_uid();
  	
  	free(platform_client);
  
  	if (problem) {
  		if (ccache)
  			krb5_cc_destroy(authctxt->krb5_ctx, ccache);
  
  		if (authctxt->krb5_ctx != NULL && problem!=-1) {
  			errmsg = krb5_get_error_message(authctxt->krb5_ctx,
  			    problem);
   			debug("Kerberos password authentication failed: %s",
  			    errmsg);
  			krb5_free_error_message(authctxt->krb5_ctx, errmsg);
  		} else
  			debug("Kerberos password authentication failed: %d",
  			    problem);
  
  		krb5_cleanup_proc(authctxt);
  
  		if (options.kerberos_or_local_passwd)
  			return (-1);
  		else
  			return (0);
  	}
  	return (authctxt->valid ? 1 : 0);
  }
  
  void
  krb5_cleanup_proc(Authctxt *authctxt)
  {
  	debug("krb5_cleanup_proc called");
  	if (authctxt->krb5_fwd_ccache) {
  		krb5_cc_destroy(authctxt->krb5_ctx, authctxt->krb5_fwd_ccache);
  		authctxt->krb5_fwd_ccache = NULL;
  	}
  	if (authctxt->krb5_user) {
  		krb5_free_principal(authctxt->krb5_ctx, authctxt->krb5_user);
  		authctxt->krb5_user = NULL;
  	}
  	if (authctxt->krb5_ctx) {
  		krb5_free_context(authctxt->krb5_ctx);
  		authctxt->krb5_ctx = NULL;
  	}
  }
  
  #ifndef HEIMDAL
  krb5_error_code
  ssh_krb5_cc_gen(krb5_context ctx, krb5_ccache *ccache) {
  	int tmpfd, ret, oerrno;
  	char ccname[40];
  	mode_t old_umask;
  
  	ret = snprintf(ccname, sizeof(ccname),
  	    "FILE:/tmp/krb5cc_%d_XXXXXXXXXX", geteuid());
  	if (ret < 0 || (size_t)ret >= sizeof(ccname))
  		return ENOMEM;
  
  	old_umask = umask(0177);
  	tmpfd = mkstemp(ccname + strlen("FILE:"));
  	oerrno = errno;
  	umask(old_umask);
  	if (tmpfd == -1) {
  		logit("mkstemp(): %.100s", strerror(oerrno));
  		return oerrno;
  	}
  
  	if (fchmod(tmpfd,S_IRUSR | S_IWUSR) == -1) {
  		oerrno = errno;
  		logit("fchmod(): %.100s", strerror(oerrno));
  		close(tmpfd);
  		return oerrno;
  	}
  	close(tmpfd);
  
  	return (krb5_cc_resolve(ctx, ccname, ccache));
  }
  #endif /* !HEIMDAL */
  #endif /* KRB5 */
  