auth-krb5.c - third_party/openssh-portable - Git at Google

 /* $OpenBSD: auth-krb5.c,v 1.23 2018/07/09 21:35:50 markus 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 "packet.h"
 #include "log.h"
 #include "sshbuf.h"
 #include "sshkey.h"
 #include "misc.h"
 #include "servconf.h"
 #include "uidswap.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 */
	/* $OpenBSD: auth-krb5.c,v 1.23 2018/07/09 21:35:50 markus 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 "packet.h"
	#include "log.h"
	#include "sshbuf.h"
	#include "sshkey.h"
	#include "misc.h"
	#include "servconf.h"
	#include "uidswap.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 */