auth2.c - third_party/openssh-portable - Git at Google

 /*
  * Copyright (c) 2000 Markus Friedl.  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. All advertising materials mentioning features or use of this software
  *    must display the following acknowledgement:
  *      This product includes software developed by Markus Friedl.
  * 4. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * 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"
 RCSID("$OpenBSD: auth2.c,v 1.11 2000/06/19 00:50:11 markus Exp $");

 #include <openssl/dsa.h>
 #include <openssl/rsa.h>
 #include <openssl/evp.h>

 #include "xmalloc.h"
 #include "rsa.h"
 #include "ssh.h"
 #include "pty.h"
 #include "packet.h"
 #include "buffer.h"
 #include "cipher.h"
 #include "servconf.h"
 #include "compat.h"
 #include "channels.h"
 #include "bufaux.h"
 #include "ssh2.h"
 #include "auth.h"
 #include "session.h"
 #include "dispatch.h"
 #include "auth.h"
 #include "key.h"
 #include "kex.h"

 #include "dsa.h"
 #include "uidswap.h"
 #include "auth-options.h"

 #ifdef HAVE_OSF_SIA
 # include <sia.h>
 # include <siad.h>
 #endif

 /* import */
 extern ServerOptions options;
 extern unsigned char *session_id2;
 extern int session_id2_len;

 /* protocol */

 void	input_service_request(int type, int plen);
 void	input_userauth_request(int type, int plen);
 void	protocol_error(int type, int plen);

 /* auth */
 int	ssh2_auth_none(struct passwd *pw);
 int	ssh2_auth_password(struct passwd *pw);
 int  	ssh2_auth_pubkey(struct passwd *pw, char *service);

 /* helper */
 struct passwd*	 auth_set_user(char *u, char *s);
 int	user_dsa_key_allowed(struct passwd *pw, Key *key);

 typedef struct Authctxt Authctxt;
 struct Authctxt {
 	char *user;
 	char *service;
 	struct passwd pw;
 	int valid;
 };
 static Authctxt	*authctxt = NULL;
 static int userauth_success = 0;

 /*
  * loop until userauth_success == TRUE
  */

 void
 do_authentication2()
 {
 	/* turn off skey/kerberos, not supported by SSH2 */
 #ifdef SKEY
 	options.skey_authentication = 0;
 #endif
 #ifdef KRB4
 	options.kerberos_authentication = 0;
 #endif

 	dispatch_init(&protocol_error);
 	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
 	dispatch_run(DISPATCH_BLOCK, &userauth_success);
 	do_authenticated2();
 }

 void
 protocol_error(int type, int plen)
 {
 	log("auth: protocol error: type %d plen %d", type, plen);
 	packet_start(SSH2_MSG_UNIMPLEMENTED);
 	packet_put_int(0);
 	packet_send();
 	packet_write_wait();
 }

 void
 input_service_request(int type, int plen)
 {
 	unsigned int len;
 	int accept = 0;
 	char *service = packet_get_string(&len);
 	packet_done();

 	if (strcmp(service, "ssh-userauth") == 0) {
 		if (!userauth_success) {
 			accept = 1;
 			/* now we can handle user-auth requests */
 			dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
 		}
 	}
 	/* XXX all other service requests are denied */

 	if (accept) {
 		packet_start(SSH2_MSG_SERVICE_ACCEPT);
 		packet_put_cstring(service);
 		packet_send();
 		packet_write_wait();
 	} else {
 		debug("bad service request %s", service);
 		packet_disconnect("bad service request %s", service);
 	}
 	xfree(service);
 }

 void
 input_userauth_request(int type, int plen)
 {
 	static void (*authlog) (const char *fmt,...) = verbose;
 	static int attempt = 0;
 	unsigned int len;
 	int authenticated = 0;
 	char *user, *service, *method, *authmsg = NULL;
 	struct passwd *pw;
 #ifdef WITH_AIXAUTHENTICATE
 	extern char *aixloginmsg;
 #endif /* WITH_AIXAUTHENTICATE */

 	user = packet_get_string(&len);
 	service = packet_get_string(&len);
 	method = packet_get_string(&len);
 	if (++attempt == AUTH_FAIL_MAX) {
 #ifdef WITH_AIXAUTHENTICATE
 		loginfailed(user,get_canonical_hostname(),"ssh");
 #endif /* WITH_AIXAUTHENTICATE */
 		packet_disconnect("too many failed userauth_requests");
 	}
 	debug("userauth-request for user %s service %s method %s", user, service, method);

 	/* XXX we only allow the ssh-connection service */
 	pw = auth_set_user(user, service);
 	if (pw && strcmp(service, "ssh-connection")==0) {
 		if (strcmp(method, "none") == 0) {
 			authenticated =	ssh2_auth_none(pw);
 		} else if (strcmp(method, "password") == 0) {
 			authenticated =	ssh2_auth_password(pw);
 		} else if (strcmp(method, "publickey") == 0) {
 			authenticated =	ssh2_auth_pubkey(pw, service);
 		}
 	}
 	if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) {
 		authenticated = 0;
 		log("ROOT LOGIN REFUSED FROM %.200s",
 		    get_canonical_hostname());
 	}

 #ifdef USE_PAM
 		if (authenticated && !do_pam_account(pw->pw_name, NULL))
 			authenticated = 0;
 #endif /* USE_PAM */

 	/* Raise logging level */
 	if (authenticated == 1 ||
 	    attempt == AUTH_FAIL_LOG ||
 	    strcmp(method, "password") == 0)
 		authlog = log;

 	/* Log before sending the reply */
 	if (authenticated == 1) {
 		authmsg = "Accepted";
 	} else if (authenticated == 0) {
 		authmsg = "Failed";
 	} else {
 		authmsg = "Postponed";
 	}
 	authlog("%s %s for %.200s from %.200s port %d ssh2",
 		authmsg,
 		method,
 		pw && pw->pw_uid == 0 ? "ROOT" : user,
 		get_remote_ipaddr(),
 		get_remote_port());

 	/* XXX todo: check if multiple auth methods are needed */
 	if (authenticated == 1) {
 #ifdef WITH_AIXAUTHENTICATE
 		/* We don't have a pty yet, so just label the line as "ssh" */
 		if (loginsuccess(user,get_canonical_hostname(),"ssh",
 				&aixloginmsg) < 0)
 			aixloginmsg = NULL;
 #endif /* WITH_AIXAUTHENTICATE */
 		/* turn off userauth */
 		dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
 		packet_start(SSH2_MSG_USERAUTH_SUCCESS);
 		packet_send();
 		packet_write_wait();
 		/* now we can break out */
 		userauth_success = 1;
 	} else if (authenticated == 0) {
 		packet_start(SSH2_MSG_USERAUTH_FAILURE);
 		packet_put_cstring("publickey,password");	/* XXX dynamic */
 		packet_put_char(0);				/* XXX partial success, unused */
 		packet_send();
 		packet_write_wait();
 	}

 	xfree(service);
 	xfree(user);
 	xfree(method);
 }

 int
 ssh2_auth_none(struct passwd *pw)
 {
 #ifdef HAVE_OSF_SIA
 	extern int saved_argc;
 	extern char **saved_argv;
 #endif

 	packet_done();

 #ifdef USE_PAM
 	return auth_pam_password(pw, "");
 #elif defined(HAVE_OSF_SIA)
 	return(sia_validate_user(NULL, saved_argc, saved_argv,
 		get_canonical_hostname(), pw->pw_name, NULL, 0, NULL,
 		"") == SIASUCCESS);
 #else /* !HAVE_OSF_SIA && !USE_PAM */
 	return auth_password(pw, "");
 #endif /* USE_PAM */
 }
 int
 ssh2_auth_password(struct passwd *pw)
 {
 	char *password;
 	int authenticated = 0;
 	int change;
 	unsigned int len;
 #ifdef HAVE_OSF_SIA
 	extern int saved_argc;
 	extern char **saved_argv;
 #endif
 	change = packet_get_char();
 	if (change)
 		log("password change not supported");
 	password = packet_get_string(&len);
 	packet_done();
 	if (options.password_authentication &&
 #ifdef USE_PAM
 	    auth_pam_password(pw, password) == 1)
 #elif defined(HAVE_OSF_SIA)
 	    sia_validate_user(NULL, saved_argc, saved_argv,
 		 	get_canonical_hostname(), pw->pw_name, NULL, 0,
 			NULL, password) == SIASUCCESS)
 #else /* !USE_PAM && !HAVE_OSF_SIA */
 	    auth_password(pw, password) == 1)
 #endif /* USE_PAM */
 		authenticated = 1;
 	memset(password, 0, len);
 	xfree(password);
 	return authenticated;
 }
 int
 ssh2_auth_pubkey(struct passwd *pw, char *service)
 {
 	Buffer b;
 	Key *key;
 	char *pkalg, *pkblob, *sig;
 	unsigned int alen, blen, slen;
 	int have_sig;
 	int authenticated = 0;

 	if (options.dsa_authentication == 0) {
 		debug("pubkey auth disabled");
 		return 0;
 	}
 	have_sig = packet_get_char();
 	pkalg = packet_get_string(&alen);
 	if (strcmp(pkalg, KEX_DSS) != 0) {
 		xfree(pkalg);
 		log("bad pkalg %s", pkalg);	/*XXX*/
 		return 0;
 	}
 	pkblob = packet_get_string(&blen);
 	key = dsa_key_from_blob(pkblob, blen);
 	if (key != NULL) {
 		if (have_sig) {
 			sig = packet_get_string(&slen);
 			packet_done();
 			buffer_init(&b);
 			if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
 				buffer_put_string(&b, session_id2, session_id2_len);
 			} else {
 				buffer_append(&b, session_id2, session_id2_len);
 			}
 			/* reconstruct packet */
 			buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
 			buffer_put_cstring(&b, pw->pw_name);
 			buffer_put_cstring(&b,
 			    datafellows & SSH_BUG_PUBKEYAUTH ?
 			    "ssh-userauth" :
 			    service);
 			buffer_put_cstring(&b, "publickey");
 			buffer_put_char(&b, have_sig);
 			buffer_put_cstring(&b, KEX_DSS);
 			buffer_put_string(&b, pkblob, blen);
 #ifdef DEBUG_DSS
 			buffer_dump(&b);
 #endif
 			/* test for correct signature */
 			if (user_dsa_key_allowed(pw, key) &&
 			    dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
 				authenticated = 1;
 			buffer_clear(&b);
 			xfree(sig);
 		} else {
 			packet_done();
 			debug("test key...");
 			/* test whether pkalg/pkblob are acceptable */
 			/* XXX fake reply and always send PK_OK ? */
 			/*
 			 * XXX this allows testing whether a user is allowed
 			 * to login: if you happen to have a valid pubkey this
 			 * message is sent. the message is NEVER sent at all
 			 * if a user is not allowed to login. is this an
 			 * issue? -markus
 			 */
 			if (user_dsa_key_allowed(pw, key)) {
 				packet_start(SSH2_MSG_USERAUTH_PK_OK);
 				packet_put_string(pkalg, alen);
 				packet_put_string(pkblob, blen);
 				packet_send();
 				packet_write_wait();
 				authenticated = -1;
 			}
 		}
 		key_free(key);
 	}
 	xfree(pkalg);
 	xfree(pkblob);
 	return authenticated;
 }

 /* set and get current user */

 struct passwd*
 auth_get_user(void)
 {
 	return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
 }

 struct passwd*
 auth_set_user(char *u, char *s)
 {
 	struct passwd *pw, *copy;

 	if (authctxt == NULL) {
 		authctxt = xmalloc(sizeof(*authctxt));
 		authctxt->valid = 0;
 		authctxt->user = xstrdup(u);
 		authctxt->service = xstrdup(s);
 		setproctitle("%s", u);
 		pw = getpwnam(u);
 		if (!pw || !allowed_user(pw)) {
 			log("auth_set_user: illegal user %s", u);
 			return NULL;
 		}
 #ifdef USE_PAM
 		start_pam(pw);
 #endif
 		copy = &authctxt->pw;
 		memset(copy, 0, sizeof(*copy));
 		copy->pw_name = xstrdup(pw->pw_name);
 		copy->pw_passwd = xstrdup(pw->pw_passwd);
 		copy->pw_uid = pw->pw_uid;
 		copy->pw_gid = pw->pw_gid;
 		copy->pw_dir = xstrdup(pw->pw_dir);
 		copy->pw_shell = xstrdup(pw->pw_shell);
 		authctxt->valid = 1;
 	} else {
 		if (strcmp(u, authctxt->user) != 0 ||
 		    strcmp(s, authctxt->service) != 0) {
 			log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)",
 			    u, s, authctxt->user, authctxt->service);
 			return NULL;
 		}
 	}
 	return auth_get_user();
 }

 /* return 1 if user allows given key */
 int
 user_dsa_key_allowed(struct passwd *pw, Key *key)
 {
 	char line[8192], file[1024];
 	int found_key = 0;
 	unsigned int bits = -1;
 	FILE *f;
 	unsigned long linenum = 0;
 	struct stat st;
 	Key *found;

 	/* Temporarily use the user's uid. */
 	temporarily_use_uid(pw->pw_uid);

 	/* The authorized keys. */
 	snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
 	    SSH_USER_PERMITTED_KEYS2);

 	/* Fail quietly if file does not exist */
 	if (stat(file, &st) < 0) {
 		/* Restore the privileged uid. */
 		restore_uid();
 		return 0;
 	}
 	/* Open the file containing the authorized keys. */
 	f = fopen(file, "r");
 	if (!f) {
 		/* Restore the privileged uid. */
 		restore_uid();
 		return 0;
 	}
 	if (options.strict_modes) {
 		int fail = 0;
 		char buf[1024];
 		/* Check open file in order to avoid open/stat races */
 		if (fstat(fileno(f), &st) < 0 ||
 		    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
 		    (st.st_mode & 022) != 0) {
 			snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: "
 			    "bad ownership or modes for '%s'.", pw->pw_name, file);
 			fail = 1;
 		} else {
 			/* Check path to SSH_USER_PERMITTED_KEYS */
 			int i;
 			static const char *check[] = {
 				"", SSH_USER_DIR, NULL
 			};
 			for (i = 0; check[i]; i++) {
 				snprintf(line, sizeof line, "%.500s/%.100s",
 				    pw->pw_dir, check[i]);
 				if (stat(line, &st) < 0 ||
 				    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
 				    (st.st_mode & 022) != 0) {
 					snprintf(buf, sizeof buf,
 					    "DSA authentication refused for %.100s: "
 					    "bad ownership or modes for '%s'.",
 					    pw->pw_name, line);
 					fail = 1;
 					break;
 				}
 			}
 		}
 		if (fail) {
 			log(buf);
 			fclose(f);
 			restore_uid();
 			return 0;
 		}
 	}
 	found_key = 0;
 	found = key_new(KEY_DSA);

 	while (fgets(line, sizeof(line), f)) {
 		char *cp, *options = NULL;
 		linenum++;
 		/* Skip leading whitespace, empty and comment lines. */
 		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
 			;
 		if (!*cp || *cp == '\n' || *cp == '#')
 			continue;

 		bits = key_read(found, &cp);
 		if (bits == 0) {
 			/* no key?  check if there are options for this key */
 			int quoted = 0;
 			options = cp;
 			for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
 				if (*cp == '\\' && cp[1] == '"')
 					cp++;	/* Skip both */
 				else if (*cp == '"')
 					quoted = !quoted;
 			}
 			/* Skip remaining whitespace. */
 			for (; *cp == ' ' || *cp == '\t'; cp++)
 				;
 			bits = key_read(found, &cp);
 			if (bits == 0) {
 				/* still no key?  advance to next line*/
 				continue;
 			}
 		}
 		if (key_equal(found, key) &&
 		    auth_parse_options(pw, options, linenum) == 1) {
 			found_key = 1;
 			debug("matching key found: file %s, line %ld",
 			    file, linenum);
 			break;
 		}
 	}
 	restore_uid();
 	fclose(f);
 	key_free(found);
 	return found_key;
 }
	/*
	* Copyright (c) 2000 Markus Friedl. 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. All advertising materials mentioning features or use of this software
	* must display the following acknowledgement:
	* This product includes software developed by Markus Friedl.
	* 4. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* 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"
	RCSID("$OpenBSD: auth2.c,v 1.11 2000/06/19 00:50:11 markus Exp $");

	#include <openssl/dsa.h>
	#include <openssl/rsa.h>
	#include <openssl/evp.h>

	#include "xmalloc.h"
	#include "rsa.h"
	#include "ssh.h"
	#include "pty.h"
	#include "packet.h"
	#include "buffer.h"
	#include "cipher.h"
	#include "servconf.h"
	#include "compat.h"
	#include "channels.h"
	#include "bufaux.h"
	#include "ssh2.h"
	#include "auth.h"
	#include "session.h"
	#include "dispatch.h"
	#include "auth.h"
	#include "key.h"
	#include "kex.h"

	#include "dsa.h"
	#include "uidswap.h"
	#include "auth-options.h"

	#ifdef HAVE_OSF_SIA
	# include <sia.h>
	# include <siad.h>
	#endif

	/* import */
	extern ServerOptions options;
	extern unsigned char *session_id2;
	extern int session_id2_len;

	/* protocol */

	void input_service_request(int type, int plen);
	void input_userauth_request(int type, int plen);
	void protocol_error(int type, int plen);

	/* auth */
	int ssh2_auth_none(struct passwd *pw);
	int ssh2_auth_password(struct passwd *pw);
	int ssh2_auth_pubkey(struct passwd pw, char service);

	/* helper */
	struct passwd* auth_set_user(char u, char s);
	int user_dsa_key_allowed(struct passwd pw, Key key);

	typedef struct Authctxt Authctxt;
	struct Authctxt {
	char *user;
	char *service;
	struct passwd pw;
	int valid;
	};
	static Authctxt *authctxt = NULL;
	static int userauth_success = 0;

	/*
	* loop until userauth_success == TRUE
	*/

	void
	do_authentication2()
	{
	/* turn off skey/kerberos, not supported by SSH2 */
	#ifdef SKEY
	options.skey_authentication = 0;
	#endif
	#ifdef KRB4
	options.kerberos_authentication = 0;
	#endif

	dispatch_init(&protocol_error);
	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
	dispatch_run(DISPATCH_BLOCK, &userauth_success);
	do_authenticated2();
	}

	void
	protocol_error(int type, int plen)
	{
	log("auth: protocol error: type %d plen %d", type, plen);
	packet_start(SSH2_MSG_UNIMPLEMENTED);
	packet_put_int(0);
	packet_send();
	packet_write_wait();
	}

	void
	input_service_request(int type, int plen)
	{
	unsigned int len;
	int accept = 0;
	char *service = packet_get_string(&len);
	packet_done();

	if (strcmp(service, "ssh-userauth") == 0) {
	if (!userauth_success) {
	accept = 1;
	/* now we can handle user-auth requests */
	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
	}
	}
	/* XXX all other service requests are denied */

	if (accept) {
	packet_start(SSH2_MSG_SERVICE_ACCEPT);
	packet_put_cstring(service);
	packet_send();
	packet_write_wait();
	} else {
	debug("bad service request %s", service);
	packet_disconnect("bad service request %s", service);
	}
	xfree(service);
	}

	void
	input_userauth_request(int type, int plen)
	{
	static void (authlog) (const char fmt,...) = verbose;
	static int attempt = 0;
	unsigned int len;
	int authenticated = 0;
	char user, service, method, authmsg = NULL;
	struct passwd *pw;
	#ifdef WITH_AIXAUTHENTICATE
	extern char *aixloginmsg;
	#endif /* WITH_AIXAUTHENTICATE */

	user = packet_get_string(&len);
	service = packet_get_string(&len);
	method = packet_get_string(&len);
	if (++attempt == AUTH_FAIL_MAX) {
	#ifdef WITH_AIXAUTHENTICATE
	loginfailed(user,get_canonical_hostname(),"ssh");
	#endif /* WITH_AIXAUTHENTICATE */
	packet_disconnect("too many failed userauth_requests");
	}
	debug("userauth-request for user %s service %s method %s", user, service, method);

	/* XXX we only allow the ssh-connection service */
	pw = auth_set_user(user, service);
	if (pw && strcmp(service, "ssh-connection")==0) {
	if (strcmp(method, "none") == 0) {
	authenticated = ssh2_auth_none(pw);
	} else if (strcmp(method, "password") == 0) {
	authenticated = ssh2_auth_password(pw);
	} else if (strcmp(method, "publickey") == 0) {
	authenticated = ssh2_auth_pubkey(pw, service);
	}
	}
	if (authenticated && pw && pw->pw_uid == 0 && !options.permit_root_login) {
	authenticated = 0;
	log("ROOT LOGIN REFUSED FROM %.200s",
	get_canonical_hostname());
	}

	#ifdef USE_PAM
	if (authenticated && !do_pam_account(pw->pw_name, NULL))
	authenticated = 0;
	#endif /* USE_PAM */

	/* Raise logging level */
	if (authenticated == 1 \|\|
	attempt == AUTH_FAIL_LOG \|\|
	strcmp(method, "password") == 0)
	authlog = log;

	/* Log before sending the reply */
	if (authenticated == 1) {
	authmsg = "Accepted";
	} else if (authenticated == 0) {
	authmsg = "Failed";
	} else {
	authmsg = "Postponed";
	}
	authlog("%s %s for %.200s from %.200s port %d ssh2",
	authmsg,
	method,
	pw && pw->pw_uid == 0 ? "ROOT" : user,
	get_remote_ipaddr(),
	get_remote_port());

	/* XXX todo: check if multiple auth methods are needed */
	if (authenticated == 1) {
	#ifdef WITH_AIXAUTHENTICATE
	/* We don't have a pty yet, so just label the line as "ssh" */
	if (loginsuccess(user,get_canonical_hostname(),"ssh",
	&aixloginmsg) < 0)
	aixloginmsg = NULL;
	#endif /* WITH_AIXAUTHENTICATE */
	/* turn off userauth */
	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error);
	packet_start(SSH2_MSG_USERAUTH_SUCCESS);
	packet_send();
	packet_write_wait();
	/* now we can break out */
	userauth_success = 1;
	} else if (authenticated == 0) {
	packet_start(SSH2_MSG_USERAUTH_FAILURE);
	packet_put_cstring("publickey,password"); /* XXX dynamic */
	packet_put_char(0); /* XXX partial success, unused */
	packet_send();
	packet_write_wait();
	}

	xfree(service);
	xfree(user);
	xfree(method);
	}

	int
	ssh2_auth_none(struct passwd *pw)
	{
	#ifdef HAVE_OSF_SIA
	extern int saved_argc;
	extern char **saved_argv;
	#endif

	packet_done();

	#ifdef USE_PAM
	return auth_pam_password(pw, "");
	#elif defined(HAVE_OSF_SIA)
	return(sia_validate_user(NULL, saved_argc, saved_argv,
	get_canonical_hostname(), pw->pw_name, NULL, 0, NULL,
	"") == SIASUCCESS);
	#else /* !HAVE_OSF_SIA && !USE_PAM */
	return auth_password(pw, "");
	#endif /* USE_PAM */
	}
	int
	ssh2_auth_password(struct passwd *pw)
	{
	char *password;
	int authenticated = 0;
	int change;
	unsigned int len;
	#ifdef HAVE_OSF_SIA
	extern int saved_argc;
	extern char **saved_argv;
	#endif
	change = packet_get_char();
	if (change)
	log("password change not supported");
	password = packet_get_string(&len);
	packet_done();
	if (options.password_authentication &&
	#ifdef USE_PAM
	auth_pam_password(pw, password) == 1)
	#elif defined(HAVE_OSF_SIA)
	sia_validate_user(NULL, saved_argc, saved_argv,
	get_canonical_hostname(), pw->pw_name, NULL, 0,
	NULL, password) == SIASUCCESS)
	#else /* !USE_PAM && !HAVE_OSF_SIA */
	auth_password(pw, password) == 1)
	#endif /* USE_PAM */
	authenticated = 1;
	memset(password, 0, len);
	xfree(password);
	return authenticated;
	}
	int
	ssh2_auth_pubkey(struct passwd pw, char service)
	{
	Buffer b;
	Key *key;
	char pkalg, pkblob, *sig;
	unsigned int alen, blen, slen;
	int have_sig;
	int authenticated = 0;

	if (options.dsa_authentication == 0) {
	debug("pubkey auth disabled");
	return 0;
	}
	have_sig = packet_get_char();
	pkalg = packet_get_string(&alen);
	if (strcmp(pkalg, KEX_DSS) != 0) {
	xfree(pkalg);
	log("bad pkalg %s", pkalg); /XXX/
	return 0;
	}
	pkblob = packet_get_string(&blen);
	key = dsa_key_from_blob(pkblob, blen);
	if (key != NULL) {
	if (have_sig) {
	sig = packet_get_string(&slen);
	packet_done();
	buffer_init(&b);
	if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
	buffer_put_string(&b, session_id2, session_id2_len);
	} else {
	buffer_append(&b, session_id2, session_id2_len);
	}
	/* reconstruct packet */
	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	buffer_put_cstring(&b, pw->pw_name);
	buffer_put_cstring(&b,
	datafellows & SSH_BUG_PUBKEYAUTH ?
	"ssh-userauth" :
	service);
	buffer_put_cstring(&b, "publickey");
	buffer_put_char(&b, have_sig);
	buffer_put_cstring(&b, KEX_DSS);
	buffer_put_string(&b, pkblob, blen);
	#ifdef DEBUG_DSS
	buffer_dump(&b);
	#endif
	/* test for correct signature */
	if (user_dsa_key_allowed(pw, key) &&
	dsa_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
	authenticated = 1;
	buffer_clear(&b);
	xfree(sig);
	} else {
	packet_done();
	debug("test key...");
	/* test whether pkalg/pkblob are acceptable */
	/* XXX fake reply and always send PK_OK ? */
	/*
	* XXX this allows testing whether a user is allowed
	* to login: if you happen to have a valid pubkey this
	* message is sent. the message is NEVER sent at all
	* if a user is not allowed to login. is this an
	* issue? -markus
	*/
	if (user_dsa_key_allowed(pw, key)) {
	packet_start(SSH2_MSG_USERAUTH_PK_OK);
	packet_put_string(pkalg, alen);
	packet_put_string(pkblob, blen);
	packet_send();
	packet_write_wait();
	authenticated = -1;
	}
	}
	key_free(key);
	}
	xfree(pkalg);
	xfree(pkblob);
	return authenticated;
	}

	/* set and get current user */

	struct passwd*
	auth_get_user(void)
	{
	return (authctxt != NULL && authctxt->valid) ? &authctxt->pw : NULL;
	}

	struct passwd*
	auth_set_user(char u, char s)
	{
	struct passwd pw, copy;

	if (authctxt == NULL) {
	authctxt = xmalloc(sizeof(*authctxt));
	authctxt->valid = 0;
	authctxt->user = xstrdup(u);
	authctxt->service = xstrdup(s);
	setproctitle("%s", u);
	pw = getpwnam(u);
	if (!pw \|\| !allowed_user(pw)) {
	log("auth_set_user: illegal user %s", u);
	return NULL;
	}
	#ifdef USE_PAM
	start_pam(pw);
	#endif
	copy = &authctxt->pw;
	memset(copy, 0, sizeof(*copy));
	copy->pw_name = xstrdup(pw->pw_name);
	copy->pw_passwd = xstrdup(pw->pw_passwd);
	copy->pw_uid = pw->pw_uid;
	copy->pw_gid = pw->pw_gid;
	copy->pw_dir = xstrdup(pw->pw_dir);
	copy->pw_shell = xstrdup(pw->pw_shell);
	authctxt->valid = 1;
	} else {
	if (strcmp(u, authctxt->user) != 0 \|\|
	strcmp(s, authctxt->service) != 0) {
	log("auth_set_user: missmatch: (%s,%s)!=(%s,%s)",
	u, s, authctxt->user, authctxt->service);
	return NULL;
	}
	}
	return auth_get_user();
	}

	/* return 1 if user allows given key */
	int
	user_dsa_key_allowed(struct passwd pw, Key key)
	{
	char line[8192], file[1024];
	int found_key = 0;
	unsigned int bits = -1;
	FILE *f;
	unsigned long linenum = 0;
	struct stat st;
	Key *found;

	/* Temporarily use the user's uid. */
	temporarily_use_uid(pw->pw_uid);

	/* The authorized keys. */
	snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
	SSH_USER_PERMITTED_KEYS2);

	/* Fail quietly if file does not exist */
	if (stat(file, &st) < 0) {
	/* Restore the privileged uid. */
	restore_uid();
	return 0;
	}
	/* Open the file containing the authorized keys. */
	f = fopen(file, "r");
	if (!f) {
	/* Restore the privileged uid. */
	restore_uid();
	return 0;
	}
	if (options.strict_modes) {
	int fail = 0;
	char buf[1024];
	/* Check open file in order to avoid open/stat races */
	if (fstat(fileno(f), &st) < 0 \|\|
	(st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
	(st.st_mode & 022) != 0) {
	snprintf(buf, sizeof buf, "DSA authentication refused for %.100s: "
	"bad ownership or modes for '%s'.", pw->pw_name, file);
	fail = 1;
	} else {
	/* Check path to SSH_USER_PERMITTED_KEYS */
	int i;
	static const char *check[] = {
	"", SSH_USER_DIR, NULL
	};
	for (i = 0; check[i]; i++) {
	snprintf(line, sizeof line, "%.500s/%.100s",
	pw->pw_dir, check[i]);
	if (stat(line, &st) < 0 \|\|
	(st.st_uid != 0 && st.st_uid != pw->pw_uid) \|\|
	(st.st_mode & 022) != 0) {
	snprintf(buf, sizeof buf,
	"DSA authentication refused for %.100s: "
	"bad ownership or modes for '%s'.",
	pw->pw_name, line);
	fail = 1;
	break;
	}
	}
	}
	if (fail) {
	log(buf);
	fclose(f);
	restore_uid();
	return 0;
	}
	}
	found_key = 0;
	found = key_new(KEY_DSA);

	while (fgets(line, sizeof(line), f)) {
	char cp, options = NULL;
	linenum++;
	/* Skip leading whitespace, empty and comment lines. */
	for (cp = line; cp == ' ' \|\| cp == '\t'; cp++)
	;
	if (!cp \|\| cp == '\n' \|\| *cp == '#')
	continue;

	bits = key_read(found, &cp);
	if (bits == 0) {
	/* no key? check if there are options for this key */
	int quoted = 0;
	options = cp;
	for (; cp && (quoted \|\| (cp != ' ' && *cp != '\t')); cp++) {
	if (*cp == '\\' && cp[1] == '"')
	cp++; /* Skip both */
	else if (*cp == '"')
	quoted = !quoted;
	}
	/* Skip remaining whitespace. */
	for (; cp == ' ' \|\| cp == '\t'; cp++)
	;
	bits = key_read(found, &cp);
	if (bits == 0) {
	/* still no key? advance to next line*/
	continue;
	}
	}
	if (key_equal(found, key) &&
	auth_parse_options(pw, options, linenum) == 1) {
	found_key = 1;
	debug("matching key found: file %s, line %ld",
	file, linenum);
	break;
	}
	}
	restore_uid();
	fclose(f);
	key_free(found);
	return found_key;
	}