[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 1.96 2003/02/06 21:22:43 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"

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

/* import */
extern ServerOptions options;
extern u_char *session_id2;
extern int session_id2_len;

Authctxt *x_authctxt = NULL;

/* methods */

extern Authmethod method_none;
extern Authmethod method_pubkey;
extern Authmethod method_passwd;
extern Authmethod method_kbdint;
extern Authmethod method_hostbased;
extern Authmethod method_external;
extern Authmethod method_gssapi;

Authmethod *authmethods[] = {
	&method_none,
#ifdef GSSAPI
	&method_external,
	&method_gssapi,
#endif
	&method_pubkey,
	&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 *);
int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);

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

Authctxt *
do_authentication2(void)
{
	Authctxt *authctxt = authctxt_new();

	x_authctxt = authctxt;		/*XXX*/

	/* challenge-response is implemented via keyboard interactive */
	if (options.challenge_response_authentication)
		options.kbd_interactive_authentication = 1;
	if (options.pam_authentication_via_kbd_int)
		options.kbd_interactive_authentication = 1;
	if (use_privsep)
		options.pam_authentication_via_kbd_int = 0;

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

	return (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));
		if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
			authctxt->valid = 1;
			debug2("input_userauth_request: setting up authctxt for %s", user);
#ifdef USE_PAM
			PRIVSEP(start_pam(authctxt->pw->pw_name));
#endif
		} else {
			log("input_userauth_request: illegal user %s", user);
#ifdef USE_PAM
			PRIVSEP(start_pam("NOUSER"));
#endif
		}
		setproctitle("%s%s", authctxt->pw ? user : "unknown",
		    use_privsep ? " [net]" : "");
		authctxt->user = xstrdup(user);
		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 USE_PAM
	if (!use_privsep && authenticated && authctxt->user && 
	    !do_pam_account(authctxt->user, NULL))
		authenticated = 0;
#endif /* USE_PAM */

#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++ > AUTH_FAIL_MAX) {
			packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
		}
#ifdef _UNICOS
		if (strcmp(method, "password") == 0)
			cray_login_failure(authctxt->user, IA_UDBERR);
#endif /* _UNICOS */
		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);
	}
}

/* get current user */

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

#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"
6a9b3198	26	RCSID("$OpenBSD: auth2.c,v 1.96 2003/02/06 21:22:43 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"
3c0ef626	38
c0fc5818	39	#ifdef GSSAPI
	40	#include "ssh-gss.h"
	41	#endif
	42
3c0ef626	43	/* import */
	44	extern ServerOptions options;
	45	extern u_char *session_id2;
	46	extern int session_id2_len;
	47
700318f3	48	Authctxt *x_authctxt = NULL;
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;
c0fc5818	57	extern Authmethod method_external;
c0fc5818	58	extern Authmethod method_gssapi;
f5799ae1	59
	60	Authmethod *authmethods[] = {
	61	&method_none,
c0fc5818	62	#ifdef GSSAPI
	63	&method_external,
	64	&method_gssapi,
	65	#endif
f5799ae1	66	&method_pubkey,
	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 );
700318f3	82	int hostbased_key_allowed(struct passwd , const char , char , Key );
3c0ef626	83
3c0ef626	84	/*
	85	* loop until authctxt->success == TRUE
	86	*/
	87
700318f3	88	Authctxt *
e9a17296	89	do_authentication2(void)
3c0ef626	90	{
	91	Authctxt *authctxt = authctxt_new();
	92
	93	x_authctxt = authctxt; /XXX/
	94
	95	/* challenge-response is implemented via keyboard interactive */
	96	if (options.challenge_response_authentication)
	97	options.kbd_interactive_authentication = 1;
	98	if (options.pam_authentication_via_kbd_int)
	99	options.kbd_interactive_authentication = 1;
700318f3	100	if (use_privsep)
700318f3	101	options.pam_authentication_via_kbd_int = 0;
3c0ef626	102
e9a17296	103	dispatch_init(&dispatch_protocol_error);
3c0ef626	104	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
3c0ef626	105	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
700318f3	106
700318f3	107	return (authctxt);
3c0ef626	108	}
	109
	110	static void
e9a17296	111	input_service_request(int type, u_int32_t seq, void *ctxt)
3c0ef626	112	{
	113	Authctxt *authctxt = ctxt;
	114	u_int len;
41b2f314	115	int acceptit = 0;
3c0ef626	116	char *service = packet_get_string(&len);
e9a17296	117	packet_check_eom();
3c0ef626	118
	119	if (authctxt == NULL)
	120	fatal("input_service_request: no authctxt");
	121
	122	if (strcmp(service, "ssh-userauth") == 0) {
	123	if (!authctxt->success) {
41b2f314	124	acceptit = 1;
3c0ef626	125	/* now we can handle user-auth requests */
	126	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
	127	}
	128	}
	129	/* XXX all other service requests are denied */
	130
41b2f314	131	if (acceptit) {
3c0ef626	132	packet_start(SSH2_MSG_SERVICE_ACCEPT);
	133	packet_put_cstring(service);
	134	packet_send();
	135	packet_write_wait();
	136	} else {
	137	debug("bad service request %s", service);
	138	packet_disconnect("bad service request %s", service);
	139	}
	140	xfree(service);
	141	}
	142
	143	static void
e9a17296	144	input_userauth_request(int type, u_int32_t seq, void *ctxt)
3c0ef626	145	{
	146	Authctxt *authctxt = ctxt;
	147	Authmethod *m = NULL;
	148	char user, service, method, style = NULL;
	149	int authenticated = 0;
	150
	151	if (authctxt == NULL)
	152	fatal("input_userauth_request: no authctxt");
	153
	154	user = packet_get_string(NULL);
	155	service = packet_get_string(NULL);
	156	method = packet_get_string(NULL);
	157	debug("userauth-request for user %s service %s method %s", user, service, method);
	158	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
	159
	160	if ((style = strchr(user, ':')) != NULL)
	161	*style++ = 0;
	162
	163	if (authctxt->attempt++ == 0) {
	164	/* setup auth context */
700318f3	165	authctxt->pw = PRIVSEP(getpwnamallow(user));
700318f3	166	if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
3c0ef626	167	authctxt->valid = 1;
	168	debug2("input_userauth_request: setting up authctxt for %s", user);
	169	#ifdef USE_PAM
700318f3	170	PRIVSEP(start_pam(authctxt->pw->pw_name));
3c0ef626	171	#endif
	172	} else {
	173	log("input_userauth_request: illegal user %s", user);
	174	#ifdef USE_PAM
700318f3	175	PRIVSEP(start_pam("NOUSER"));
3c0ef626	176	#endif
3c0ef626	177	}
700318f3	178	setproctitle("%s%s", authctxt->pw ? user : "unknown",
700318f3	179	use_privsep ? " [net]" : "");
3c0ef626	180	authctxt->user = xstrdup(user);
	181	authctxt->service = xstrdup(service);
	182	authctxt->style = style ? xstrdup(style) : NULL;
700318f3	183	if (use_privsep)
700318f3	184	mm_inform_authserv(service, style);
3c0ef626	185	} else if (strcmp(user, authctxt->user) != 0 \|\|
	186	strcmp(service, authctxt->service) != 0) {
	187	packet_disconnect("Change of username or service not allowed: "
	188	"(%s,%s) -> (%s,%s)",
	189	authctxt->user, authctxt->service, user, service);
	190	}
	191	/* reset state */
e9a17296	192	auth2_challenge_stop(authctxt);
c0fc5818	193
	194	#ifdef GSSAPI
	195	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	196	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	197	#endif
	198
3c0ef626	199	authctxt->postponed = 0;
3c0ef626	200
	201	/* try to authenticate user */
	202	m = authmethod_lookup(method);
	203	if (m != NULL) {
	204	debug2("input_userauth_request: try method %s", method);
	205	authenticated = m->userauth(authctxt);
	206	}
	207	userauth_finish(authctxt, authenticated, method);
	208
	209	xfree(service);
	210	xfree(user);
	211	xfree(method);
	212	}
	213
	214	void
	215	userauth_finish(Authctxt authctxt, int authenticated, char method)
	216	{
	217	char *methods;
	218
	219	if (!authctxt->valid && authenticated)
	220	fatal("INTERNAL ERROR: authenticated invalid user %s",
	221	authctxt->user);
	222
	223	/* Special handling for root */
6a9b3198	224	if (authenticated && authctxt->pw->pw_uid == 0 &&
3c0ef626	225	!auth_root_allowed(method))
	226	authenticated = 0;
	227
	228	#ifdef USE_PAM
700318f3	229	if (!use_privsep && authenticated && authctxt->user &&
700318f3	230	!do_pam_account(authctxt->user, NULL))
3c0ef626	231	authenticated = 0;
	232	#endif /* USE_PAM */
	233
41b2f314	234	#ifdef _UNICOS
	235	if (authenticated && cray_access_denied(authctxt->user)) {
	236	authenticated = 0;
	237	fatal("Access denied for user %s.",authctxt->user);
	238	}
	239	#endif /* _UNICOS */
	240
3c0ef626	241	/* Log before sending the reply */
	242	auth_log(authctxt, authenticated, method, " ssh2");
	243
	244	if (authctxt->postponed)
	245	return;
	246
	247	/* XXX todo: check if multiple auth methods are needed */
	248	if (authenticated == 1) {
	249	/* turn off userauth */
e9a17296	250	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
3c0ef626	251	packet_start(SSH2_MSG_USERAUTH_SUCCESS);
	252	packet_send();
	253	packet_write_wait();
	254	/* now we can break out */
	255	authctxt->success = 1;
	256	} else {
	257	if (authctxt->failures++ > AUTH_FAIL_MAX) {
3c0ef626	258	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
3c0ef626	259	}
41b2f314	260	#ifdef _UNICOS
	261	if (strcmp(method, "password") == 0)
	262	cray_login_failure(authctxt->user, IA_UDBERR);
	263	#endif /* _UNICOS */
3c0ef626	264	methods = authmethods_get();
	265	packet_start(SSH2_MSG_USERAUTH_FAILURE);
	266	packet_put_cstring(methods);
	267	packet_put_char(0); /* XXX partial success, unused */
	268	packet_send();
	269	packet_write_wait();
	270	xfree(methods);
	271	}
	272	}
	273
3c0ef626	274	/* get current user */
	275
	276	struct passwd*
	277	auth_get_user(void)
	278	{
	279	return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
	280	}
	281
	282	#define DELIM ","
	283
	284	static char *
	285	authmethods_get(void)
	286	{
e9a17296	287	Buffer b;
3c0ef626	288	char *list;
f5799ae1	289	int i;
3c0ef626	290
e9a17296	291	buffer_init(&b);
f5799ae1	292	for (i = 0; authmethods[i] != NULL; i++) {
f5799ae1	293	if (strcmp(authmethods[i]->name, "none") == 0)
3c0ef626	294	continue;
f5799ae1	295	if (authmethods[i]->enabled != NULL &&
f5799ae1	296	*(authmethods[i]->enabled) != 0) {
e9a17296	297	if (buffer_len(&b) > 0)
e9a17296	298	buffer_append(&b, ",", 1);
f5799ae1	299	buffer_append(&b, authmethods[i]->name,
f5799ae1	300	strlen(authmethods[i]->name));
3c0ef626	301	}
3c0ef626	302	}
e9a17296	303	buffer_append(&b, "\0", 1);
	304	list = xstrdup(buffer_ptr(&b));
	305	buffer_free(&b);
3c0ef626	306	return list;
	307	}
	308
	309	static Authmethod *
	310	authmethod_lookup(const char *name)
	311	{
f5799ae1	312	int i;
f5799ae1	313
3c0ef626	314	if (name != NULL)
f5799ae1	315	for (i = 0; authmethods[i] != NULL; i++)
	316	if (authmethods[i]->enabled != NULL &&
	317	*(authmethods[i]->enabled) != 0 &&
	318	strcmp(name, authmethods[i]->name) == 0)
	319	return authmethods[i];
	320	debug2("Unrecognized authentication method name: %s",
	321	name ? name : "NULL");
3c0ef626	322	return NULL;
3c0ef626	323	}