[gssapi-openssh.git] / openssh / auth2.c

/*
 * 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.
 *
 * 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 1.107 2004/07/28 09:40:29 markus Exp $");

#include "ssh2.h"
#include "xmalloc.h"
#include "packet.h"
#include "log.h"
#include "servconf.h"
#include "compat.h"
#include "auth.h"
#include "dispatch.h"
#include "pathnames.h"
#include "monitor_wrap.h"
#include "buffer.h"

#ifdef GSSAPI
#include "ssh-gss.h"
#endif

/* import */
extern ServerOptions options;
extern u_char *session_id2;
extern u_int session_id2_len;
extern Buffer loginmsg;

/* methods */

extern Authmethod method_none;
extern Authmethod method_pubkey;
extern Authmethod method_passwd;
extern Authmethod method_kbdint;
extern Authmethod method_hostbased;
#ifdef GSSAPI
extern Authmethod method_gssapi;
#endif

Authmethod *authmethods[] = {
	&method_none,
	&method_pubkey,
#ifdef GSSAPI
	&method_gssapi,
#endif
	&method_passwd,
	&method_kbdint,
	&method_hostbased,
	NULL
};

/* protocol */

static void input_service_request(int, u_int32_t, void *);
static void input_userauth_request(int, u_int32_t, void *);

/* helper */
static Authmethod *authmethod_lookup(const char *);
static char *authmethods_get(void);
int user_key_allowed(struct passwd *, Key *);

/*
 * loop until authctxt->success == TRUE
 */

void
do_authentication2(Authctxt *authctxt)
{
	/* challenge-response is implemented via keyboard interactive */
	if (options.challenge_response_authentication)
		options.kbd_interactive_authentication = 1;

	dispatch_init(&dispatch_protocol_error);
	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
}

static void
input_service_request(int type, u_int32_t seq, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	u_int len;
	int acceptit = 0;
	char *service = packet_get_string(&len);
	packet_check_eom();

	if (authctxt == NULL)
		fatal("input_service_request: no authctxt");

	if (strcmp(service, "ssh-userauth") == 0) {
		if (!authctxt->success) {
			acceptit = 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 (acceptit) {
		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);
}

static void
input_userauth_request(int type, u_int32_t seq, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Authmethod *m = NULL;
	char *user, *service, *method, *style = NULL;
	int authenticated = 0;

	if (authctxt == NULL)
		fatal("input_userauth_request: no authctxt");

	user = packet_get_string(NULL);
	service = packet_get_string(NULL);
	method = packet_get_string(NULL);
	debug("userauth-request for user %s service %s method %s", user, service, method);
	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);

	if ((style = strchr(user, ':')) != NULL)
		*style++ = 0;

	if (authctxt->attempt++ == 0) {
		/* setup auth context */
		authctxt->pw = PRIVSEP(getpwnamallow(user));
		authctxt->user = xstrdup(user);
		if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
			authctxt->valid = 1;
			debug2("input_userauth_request: setting up authctxt for %s", user);
		} else {
			logit("input_userauth_request: invalid user %s", user);
			authctxt->pw = fakepw();
#ifdef SSH_AUDIT_EVENTS
			PRIVSEP(audit_event(SSH_INVALID_USER));
#endif
		}
#ifdef USE_PAM
		if (options.use_pam)
			PRIVSEP(start_pam(authctxt));
#endif
		setproctitle("%s%s", authctxt->valid ? user : "unknown",
		    use_privsep ? " [net]" : "");
		authctxt->service = xstrdup(service);
		authctxt->style = style ? xstrdup(style) : NULL;
		if (use_privsep)
			mm_inform_authserv(service, style);
	} else if (strcmp(user, authctxt->user) != 0 ||
	    strcmp(service, authctxt->service) != 0) {
		packet_disconnect("Change of username or service not allowed: "
		    "(%s,%s) -> (%s,%s)",
		    authctxt->user, authctxt->service, user, service);
	}
	/* reset state */
	auth2_challenge_stop(authctxt);

#ifdef GSSAPI
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
#endif

	authctxt->postponed = 0;

	/* try to authenticate user */
	m = authmethod_lookup(method);
	if (m != NULL) {
		debug2("input_userauth_request: try method %s", method);
		authenticated =	m->userauth(authctxt);
	}
	userauth_finish(authctxt, authenticated, method);

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

void
userauth_finish(Authctxt *authctxt, int authenticated, char *method)
{
	char *methods;

	if (!authctxt->valid && authenticated)
		fatal("INTERNAL ERROR: authenticated invalid user %s",
		    authctxt->user);

	/* Special handling for root */
	if (authenticated && authctxt->pw->pw_uid == 0 &&
	    !auth_root_allowed(method)) {
		authenticated = 0;
#ifdef SSH_AUDIT_EVENTS
		PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
#endif
	}

#ifdef USE_PAM
	if (options.use_pam && authenticated) {
		if (!PRIVSEP(do_pam_account())) {
			/* if PAM returned a message, send it to the user */
			if (buffer_len(&loginmsg) > 0) {
				buffer_append(&loginmsg, "\0", 1);
				userauth_send_banner(buffer_ptr(&loginmsg));
				packet_write_wait();
			}
			fatal("Access denied for user %s by PAM account "
			    "configuration", authctxt->user);
		}
	}
#endif

#ifdef _UNICOS
	if (authenticated && cray_access_denied(authctxt->user)) {
		authenticated = 0;
		fatal("Access denied for user %s.",authctxt->user);
	}
#endif /* _UNICOS */

	/* Log before sending the reply */
	auth_log(authctxt, authenticated, method, " ssh2");

	if (authctxt->postponed)
		return;

	/* XXX todo: check if multiple auth methods are needed */
	if (authenticated == 1) {
		/* turn off userauth */
		dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
		packet_start(SSH2_MSG_USERAUTH_SUCCESS);
		packet_send();
		packet_write_wait();
		/* now we can break out */
		authctxt->success = 1;
	} else {
		if (authctxt->failures++ > options.max_authtries) {
#ifdef SSH_AUDIT_EVENTS
			PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
#endif
			packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
		}
		methods = authmethods_get();
		packet_start(SSH2_MSG_USERAUTH_FAILURE);
		packet_put_cstring(methods);
		packet_put_char(0);	/* XXX partial success, unused */
		packet_send();
		packet_write_wait();
		xfree(methods);
	}
}

#define	DELIM	","

static char *
authmethods_get(void)
{
	Buffer b;
	char *list;
	int i;

	buffer_init(&b);
	for (i = 0; authmethods[i] != NULL; i++) {
		if (strcmp(authmethods[i]->name, "none") == 0)
			continue;
		if (authmethods[i]->enabled != NULL &&
		    *(authmethods[i]->enabled) != 0) {
			if (buffer_len(&b) > 0)
				buffer_append(&b, ",", 1);
			buffer_append(&b, authmethods[i]->name,
			    strlen(authmethods[i]->name));
		}
	}
	buffer_append(&b, "\0", 1);
	list = xstrdup(buffer_ptr(&b));
	buffer_free(&b);
	return list;
}

static Authmethod *
authmethod_lookup(const char *name)
{
	int i;

	if (name != NULL)
		for (i = 0; authmethods[i] != NULL; i++)
			if (authmethods[i]->enabled != NULL &&
			    *(authmethods[i]->enabled) != 0 &&
			    strcmp(name, authmethods[i]->name) == 0)
				return authmethods[i];
	debug2("Unrecognized authentication method name: %s",
	    name ? name : "NULL");
	return NULL;
}
Commit	Line	Data
3c0ef626	1	/*
	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
c9f39d2c	26	RCSID("$OpenBSD: auth2.c,v 1.107 2004/07/28 09:40:29 markus Exp $");
3c0ef626	27
	28	#include "ssh2.h"
	29	#include "xmalloc.h"
3c0ef626	30	#include "packet.h"
3c0ef626	31	#include "log.h"
	32	#include "servconf.h"
	33	#include "compat.h"
3c0ef626	34	#include "auth.h"
3c0ef626	35	#include "dispatch.h"
3c0ef626	36	#include "pathnames.h"
700318f3	37	#include "monitor_wrap.h"
996d5e62	38	#include "buffer.h"
3c0ef626	39
0fff78ff	40	#ifdef GSSAPI
	41	#include "ssh-gss.h"
	42	#endif
	43
3c0ef626	44	/* import */
	45	extern ServerOptions options;
	46	extern u_char *session_id2;
0fff78ff	47	extern u_int session_id2_len;
996d5e62	48	extern Buffer loginmsg;
3c0ef626	49
f5799ae1	50	/* methods */
	51
	52	extern Authmethod method_none;
	53	extern Authmethod method_pubkey;
	54	extern Authmethod method_passwd;
	55	extern Authmethod method_kbdint;
	56	extern Authmethod method_hostbased;
0fff78ff	57	#ifdef GSSAPI
	58	extern Authmethod method_gssapi;
	59	#endif
f5799ae1	60
	61	Authmethod *authmethods[] = {
	62	&method_none,
	63	&method_pubkey,
0fff78ff	64	#ifdef GSSAPI
	65	&method_gssapi,
	66	#endif
f5799ae1	67	&method_passwd,
	68	&method_kbdint,
	69	&method_hostbased,
	70	NULL
3c0ef626	71	};
	72
	73	/* protocol */
	74
e9a17296	75	static void input_service_request(int, u_int32_t, void *);
e9a17296	76	static void input_userauth_request(int, u_int32_t, void *);
3c0ef626	77
	78	/* helper */
	79	static Authmethod authmethod_lookup(const char );
	80	static char *authmethods_get(void);
700318f3	81	int user_key_allowed(struct passwd , Key );
3c0ef626	82
3c0ef626	83	/*
	84	* loop until authctxt->success == TRUE
	85	*/
	86
cdd66111	87	void
cdd66111	88	do_authentication2(Authctxt *authctxt)
3c0ef626	89	{
3c0ef626	90	/* challenge-response is implemented via keyboard interactive */
	91	if (options.challenge_response_authentication)
	92	options.kbd_interactive_authentication = 1;
3c0ef626	93
e9a17296	94	dispatch_init(&dispatch_protocol_error);
3c0ef626	95	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
3c0ef626	96	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
3c0ef626	97	}
	98
	99	static void
e9a17296	100	input_service_request(int type, u_int32_t seq, void *ctxt)
3c0ef626	101	{
	102	Authctxt *authctxt = ctxt;
	103	u_int len;
41b2f314	104	int acceptit = 0;
3c0ef626	105	char *service = packet_get_string(&len);
e9a17296	106	packet_check_eom();
3c0ef626	107
	108	if (authctxt == NULL)
	109	fatal("input_service_request: no authctxt");
	110
	111	if (strcmp(service, "ssh-userauth") == 0) {
	112	if (!authctxt->success) {
41b2f314	113	acceptit = 1;
3c0ef626	114	/* now we can handle user-auth requests */
	115	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
	116	}
	117	}
	118	/* XXX all other service requests are denied */
	119
41b2f314	120	if (acceptit) {
3c0ef626	121	packet_start(SSH2_MSG_SERVICE_ACCEPT);
	122	packet_put_cstring(service);
	123	packet_send();
	124	packet_write_wait();
	125	} else {
	126	debug("bad service request %s", service);
	127	packet_disconnect("bad service request %s", service);
	128	}
	129	xfree(service);
	130	}
	131
	132	static void
e9a17296	133	input_userauth_request(int type, u_int32_t seq, void *ctxt)
3c0ef626	134	{
	135	Authctxt *authctxt = ctxt;
	136	Authmethod *m = NULL;
	137	char user, service, method, style = NULL;
	138	int authenticated = 0;
	139
	140	if (authctxt == NULL)
	141	fatal("input_userauth_request: no authctxt");
	142
	143	user = packet_get_string(NULL);
	144	service = packet_get_string(NULL);
	145	method = packet_get_string(NULL);
	146	debug("userauth-request for user %s service %s method %s", user, service, method);
	147	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
	148
	149	if ((style = strchr(user, ':')) != NULL)
	150	*style++ = 0;
	151
	152	if (authctxt->attempt++ == 0) {
	153	/* setup auth context */
700318f3	154	authctxt->pw = PRIVSEP(getpwnamallow(user));
99be0775	155	authctxt->user = xstrdup(user);
700318f3	156	if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
3c0ef626	157	authctxt->valid = 1;
3c0ef626	158	debug2("input_userauth_request: setting up authctxt for %s", user);
3c0ef626	159	} else {
c9f39d2c	160	logit("input_userauth_request: invalid user %s", user);
0fff78ff	161	authctxt->pw = fakepw();
996d5e62	162	#ifdef SSH_AUDIT_EVENTS
996d5e62	163	PRIVSEP(audit_event(SSH_INVALID_USER));
3c0ef626	164	#endif
3c0ef626	165	}
2c06c99b	166	#ifdef USE_PAM
	167	if (options.use_pam)
	168	PRIVSEP(start_pam(authctxt));
	169	#endif
c9f39d2c	170	setproctitle("%s%s", authctxt->valid ? user : "unknown",
700318f3	171	use_privsep ? " [net]" : "");
3c0ef626	172	authctxt->service = xstrdup(service);
3c0ef626	173	authctxt->style = style ? xstrdup(style) : NULL;
700318f3	174	if (use_privsep)
700318f3	175	mm_inform_authserv(service, style);
3c0ef626	176	} else if (strcmp(user, authctxt->user) != 0 \|\|
	177	strcmp(service, authctxt->service) != 0) {
	178	packet_disconnect("Change of username or service not allowed: "
	179	"(%s,%s) -> (%s,%s)",
	180	authctxt->user, authctxt->service, user, service);
	181	}
	182	/* reset state */
e9a17296	183	auth2_challenge_stop(authctxt);
0fff78ff	184
	185	#ifdef GSSAPI
	186	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	187	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	188	#endif
	189
3c0ef626	190	authctxt->postponed = 0;
3c0ef626	191
	192	/* try to authenticate user */
	193	m = authmethod_lookup(method);
	194	if (m != NULL) {
	195	debug2("input_userauth_request: try method %s", method);
	196	authenticated = m->userauth(authctxt);
	197	}
	198	userauth_finish(authctxt, authenticated, method);
	199
	200	xfree(service);
	201	xfree(user);
	202	xfree(method);
	203	}
	204
	205	void
	206	userauth_finish(Authctxt authctxt, int authenticated, char method)
	207	{
	208	char *methods;
	209
	210	if (!authctxt->valid && authenticated)
	211	fatal("INTERNAL ERROR: authenticated invalid user %s",
	212	authctxt->user);
	213
	214	/* Special handling for root */
6a9b3198	215	if (authenticated && authctxt->pw->pw_uid == 0 &&
996d5e62	216	!auth_root_allowed(method)) {
3c0ef626	217	authenticated = 0;
996d5e62	218	#ifdef SSH_AUDIT_EVENTS
	219	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
	220	#endif
	221	}
3c0ef626	222
3c0ef626	223	#ifdef USE_PAM
996d5e62	224	if (options.use_pam && authenticated) {
	225	if (!PRIVSEP(do_pam_account())) {
	226	/* if PAM returned a message, send it to the user */
	227	if (buffer_len(&loginmsg) > 0) {
	228	buffer_append(&loginmsg, "\0", 1);
	229	userauth_send_banner(buffer_ptr(&loginmsg));
	230	packet_write_wait();
	231	}
	232	fatal("Access denied for user %s by PAM account "
665a873d	233	"configuration", authctxt->user);
996d5e62	234	}
996d5e62	235	}
0fff78ff	236	#endif
3c0ef626	237
41b2f314	238	#ifdef _UNICOS
	239	if (authenticated && cray_access_denied(authctxt->user)) {
	240	authenticated = 0;
	241	fatal("Access denied for user %s.",authctxt->user);
	242	}
	243	#endif /* _UNICOS */
	244
3c0ef626	245	/* Log before sending the reply */
	246	auth_log(authctxt, authenticated, method, " ssh2");
	247
	248	if (authctxt->postponed)
	249	return;
	250
	251	/* XXX todo: check if multiple auth methods are needed */
	252	if (authenticated == 1) {
	253	/* turn off userauth */
e9a17296	254	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
3c0ef626	255	packet_start(SSH2_MSG_USERAUTH_SUCCESS);
	256	packet_send();
	257	packet_write_wait();
	258	/* now we can break out */
	259	authctxt->success = 1;
	260	} else {
996d5e62	261	if (authctxt->failures++ > options.max_authtries) {
	262	#ifdef SSH_AUDIT_EVENTS
	263	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
	264	#endif
3c0ef626	265	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
996d5e62	266	}
3c0ef626	267	methods = authmethods_get();
	268	packet_start(SSH2_MSG_USERAUTH_FAILURE);
	269	packet_put_cstring(methods);
	270	packet_put_char(0); /* XXX partial success, unused */
	271	packet_send();
	272	packet_write_wait();
	273	xfree(methods);
	274	}
	275	}
	276
3c0ef626	277	#define DELIM ","
	278
	279	static char *
	280	authmethods_get(void)
	281	{
e9a17296	282	Buffer b;
3c0ef626	283	char *list;
f5799ae1	284	int i;
3c0ef626	285
e9a17296	286	buffer_init(&b);
f5799ae1	287	for (i = 0; authmethods[i] != NULL; i++) {
f5799ae1	288	if (strcmp(authmethods[i]->name, "none") == 0)
3c0ef626	289	continue;
f5799ae1	290	if (authmethods[i]->enabled != NULL &&
f5799ae1	291	*(authmethods[i]->enabled) != 0) {
e9a17296	292	if (buffer_len(&b) > 0)
e9a17296	293	buffer_append(&b, ",", 1);
f5799ae1	294	buffer_append(&b, authmethods[i]->name,
f5799ae1	295	strlen(authmethods[i]->name));
3c0ef626	296	}
3c0ef626	297	}
e9a17296	298	buffer_append(&b, "\0", 1);
	299	list = xstrdup(buffer_ptr(&b));
	300	buffer_free(&b);
3c0ef626	301	return list;
	302	}
	303
	304	static Authmethod *
	305	authmethod_lookup(const char *name)
	306	{
f5799ae1	307	int i;
f5799ae1	308
3c0ef626	309	if (name != NULL)
f5799ae1	310	for (i = 0; authmethods[i] != NULL; i++)
	311	if (authmethods[i]->enabled != NULL &&
	312	*(authmethods[i]->enabled) != 0 &&
	313	strcmp(name, authmethods[i]->name) == 0)
	314	return authmethods[i];
	315	debug2("Unrecognized authentication method name: %s",
	316	name ? name : "NULL");
3c0ef626	317	return NULL;
3c0ef626	318	}