[openssh.git] / 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 1.93 2002/05/31 11:35:15 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"

/* 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;

Authmethod *authmethods[] = {
	&method_none,
	&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 accept = 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) {
			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);
}

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);
	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 */

	/* 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) {
#ifdef WITH_AIXAUTHENTICATE
			loginfailed(authctxt->user,
			    get_canonical_hostname(options.verify_reverse_mapping),
			    "ssh");
#endif /* WITH_AIXAUTHENTICATE */
			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);
	}
}

char *
auth2_read_banner(void)
{
	struct stat st;
	char *banner = NULL;
	off_t len, n;
	int fd;

	if ((fd = open(options.banner, O_RDONLY)) == -1)
		return (NULL);
	if (fstat(fd, &st) == -1) {
		close(fd);
		return (NULL);
	}
	len = st.st_size;
	banner = xmalloc(len + 1);
	n = atomicio(read, fd, banner, len);
	close(fd);

	if (n != len) {
		free(banner);
		return (NULL);
	}
	banner[n] = '\0';
	
	return (banner);
}

static void
userauth_banner(void)
{
	char *banner = NULL;

	if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
		return;

	if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
		goto done;

	packet_start(SSH2_MSG_USERAUTH_BANNER);
	packet_put_cstring(banner);
	packet_put_cstring("");		/* language, unused */
	packet_send();
	debug("userauth_banner: sent");
done:
	if (banner)
		xfree(banner);
	return;
}

static int
userauth_none(Authctxt *authctxt)
{
	/* disable method "none", only allowed one time */
	Authmethod *m = authmethod_lookup("none");
	if (m != NULL)
		m->enabled = NULL;
	packet_check_eom();
	userauth_banner();

	if (authctxt->valid == 0)
		return(0);

#ifdef HAVE_CYGWIN
	if (check_nt_auth(1, authctxt->pw) == 0)
		return(0);
#endif
	return PRIVSEP(auth_password(authctxt, ""));
}

static int
userauth_passwd(Authctxt *authctxt)
{
	char *password;
	int authenticated = 0;
	int change;
	u_int len;
	change = packet_get_char();
	if (change)
		log("password change not supported");
	password = packet_get_string(&len);
	packet_check_eom();
	if (authctxt->valid &&
#ifdef HAVE_CYGWIN
	    check_nt_auth(1, authctxt->pw) &&
#endif
	    PRIVSEP(auth_password(authctxt, password)) == 1)
		authenticated = 1;
	memset(password, 0, len);
	xfree(password);
	return authenticated;
}

static int
userauth_kbdint(Authctxt *authctxt)
{
	int authenticated = 0;
	char *lang, *devs;

	lang = packet_get_string(NULL);
	devs = packet_get_string(NULL);
	packet_check_eom();

	debug("keyboard-interactive devs %s", devs);

	if (options.challenge_response_authentication)
		authenticated = auth2_challenge(authctxt, devs);

#ifdef USE_PAM
	if (authenticated == 0 && options.pam_authentication_via_kbd_int)
		authenticated = auth2_pam(authctxt);
#endif
	xfree(devs);
	xfree(lang);
#ifdef HAVE_CYGWIN
	if (check_nt_auth(0, authctxt->pw) == 0)
		return(0);
#endif
	return authenticated;
}

static int
userauth_pubkey(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_pubkey: disabled because of invalid user");
		return 0;
	}
	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		log("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&b, authctxt->user);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		/* test for correct signature */
		authenticated = 0;
		if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
				buffer_len(&b))) == 1)
			authenticated = 1;
		buffer_clear(&b);
		xfree(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* 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 (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->postponed = 1;
		}
	}
	if (authenticated != 1)
		auth_clear_options();
done:
	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
#ifdef HAVE_CYGWIN
	if (check_nt_auth(0, authctxt->pw) == 0)
		return(0);
#endif
	return authenticated;
}

static int
userauth_hostbased(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg, *cuser, *chost, *service;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_hostbased: disabled because of invalid user");
		return 0;
	}
	pkalg = packet_get_string(&alen);
	pkblob = packet_get_string(&blen);
	chost = packet_get_string(NULL);
	cuser = packet_get_string(NULL);
	sig = packet_get_string(&slen);

	debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
	    cuser, chost, pkalg, slen);
#ifdef DEBUG_PK
	debug("signature:");
	buffer_init(&b);
	buffer_append(&b, sig, slen);
	buffer_dump(&b);
	buffer_free(&b);
#endif
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		log("userauth_hostbased: unsupported "
		    "public key algorithm: %s", pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_hostbased: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_hostbased: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
	    authctxt->service;
	buffer_init(&b);
	buffer_put_string(&b, session_id2, session_id2_len);
	/* reconstruct packet */
	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	buffer_put_cstring(&b, authctxt->user);
	buffer_put_cstring(&b, service);
	buffer_put_cstring(&b, "hostbased");
	buffer_put_string(&b, pkalg, alen);
	buffer_put_string(&b, pkblob, blen);
	buffer_put_cstring(&b, chost);
	buffer_put_cstring(&b, cuser);
#ifdef DEBUG_PK
	buffer_dump(&b);
#endif
	/* test for allowed key and correct signature */
	authenticated = 0;
	if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
	    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
			buffer_len(&b))) == 1)
		authenticated = 1;

	buffer_clear(&b);
done:
	debug2("userauth_hostbased: authenticated %d", authenticated);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
	xfree(cuser);
	xfree(chost);
	xfree(sig);
	return authenticated;
}

/* 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
a306f2dd	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.
a306f2dd	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	*/
bcbf86ec	24
a306f2dd	25	#include "includes.h"
01c24737	26	RCSID("$OpenBSD: auth2.c,v 1.93 2002/05/31 11:35:15 markus Exp $");
a306f2dd	27
42f11eb2	28	#include "ssh2.h"
a306f2dd	29	#include "xmalloc.h"
a306f2dd	30	#include "packet.h"
42f11eb2	31	#include "log.h"
a306f2dd	32	#include "servconf.h"
a306f2dd	33	#include "compat.h"
a306f2dd	34	#include "auth.h"
a306f2dd	35	#include "dispatch.h"
42f11eb2	36	#include "pathnames.h"
1853d1ef	37	#include "monitor_wrap.h"
a306f2dd	38
	39	/* import */
	40	extern ServerOptions options;
1e3b8b07	41	extern u_char *session_id2;
a306f2dd	42	extern int session_id2_len;
a306f2dd	43
1853d1ef	44	Authctxt *x_authctxt = NULL;
94ec8c6b	45
01c24737	46	/* methods */
	47
	48	extern Authmethod method_none;
	49	extern Authmethod method_pubkey;
	50	extern Authmethod method_passwd;
	51	extern Authmethod method_kbdint;
	52	extern Authmethod method_hostbased;
	53
	54	Authmethod *authmethods[] = {
	55	&method_none,
	56	&method_pubkey,
	57	&method_passwd,
	58	&method_kbdint,
	59	&method_hostbased,
	60	NULL
94ec8c6b	61	};
94ec8c6b	62
a306f2dd	63	/* protocol */
a306f2dd	64
7819b5c3	65	static void input_service_request(int, u_int32_t, void *);
7819b5c3	66	static void input_userauth_request(int, u_int32_t, void *);
a306f2dd	67
a306f2dd	68	/* helper */
396c147e	69	static Authmethod authmethod_lookup(const char );
ffb215be	70	static char *authmethods_get(void);
1853d1ef	71	int user_key_allowed(struct passwd , Key );
1853d1ef	72	int hostbased_key_allowed(struct passwd , const char , char , Key );
a306f2dd	73
a306f2dd	74	/*
94ec8c6b	75	* loop until authctxt->success == TRUE
a306f2dd	76	*/
a306f2dd	77
1b34c1b3	78	Authctxt *
d5bb9418	79	do_authentication2(void)
a306f2dd	80	{
59c97189	81	Authctxt *authctxt = authctxt_new();
59c97189	82
94ec8c6b	83	x_authctxt = authctxt; /XXX/
94ec8c6b	84
aa8003d6	85	/* challenge-response is implemented via keyboard interactive */
5ba55ada	86	if (options.challenge_response_authentication)
d464095c	87	options.kbd_interactive_authentication = 1;
10f72868	88	if (options.pam_authentication_via_kbd_int)
10f72868	89	options.kbd_interactive_authentication = 1;
fea8a8e8	90	if (use_privsep)
fea8a8e8	91	options.pam_authentication_via_kbd_int = 0;
d464095c	92
6367063f	93	dispatch_init(&dispatch_protocol_error);
a306f2dd	94	dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
94ec8c6b	95	dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
1b34c1b3	96
1b34c1b3	97	return (authctxt);
a306f2dd	98	}
a306f2dd	99
396c147e	100	static void
7819b5c3	101	input_service_request(int type, u_int32_t seq, void *ctxt)
a306f2dd	102	{
94ec8c6b	103	Authctxt *authctxt = ctxt;
1e3b8b07	104	u_int len;
a306f2dd	105	int accept = 0;
a306f2dd	106	char *service = packet_get_string(&len);
95500969	107	packet_check_eom();
a306f2dd	108
94ec8c6b	109	if (authctxt == NULL)
	110	fatal("input_service_request: no authctxt");
	111
a306f2dd	112	if (strcmp(service, "ssh-userauth") == 0) {
94ec8c6b	113	if (!authctxt->success) {
a306f2dd	114	accept = 1;
	115	/* now we can handle user-auth requests */
	116	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
	117	}
	118	}
	119	/* XXX all other service requests are denied */
	120
	121	if (accept) {
	122	packet_start(SSH2_MSG_SERVICE_ACCEPT);
	123	packet_put_cstring(service);
	124	packet_send();
	125	packet_write_wait();
	126	} else {
	127	debug("bad service request %s", service);
	128	packet_disconnect("bad service request %s", service);
	129	}
	130	xfree(service);
	131	}
	132
396c147e	133	static void
7819b5c3	134	input_userauth_request(int type, u_int32_t seq, void *ctxt)
a306f2dd	135	{
94ec8c6b	136	Authctxt *authctxt = ctxt;
94ec8c6b	137	Authmethod *m = NULL;
59c97189	138	char user, service, method, style = NULL;
a306f2dd	139	int authenticated = 0;
a306f2dd	140
94ec8c6b	141	if (authctxt == NULL)
94ec8c6b	142	fatal("input_userauth_request: no authctxt");
a306f2dd	143
94ec8c6b	144	user = packet_get_string(NULL);
	145	service = packet_get_string(NULL);
	146	method = packet_get_string(NULL);
	147	debug("userauth-request for user %s service %s method %s", user, service, method);
8abcdba4	148	debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
94ec8c6b	149
59c97189	150	if ((style = strchr(user, ':')) != NULL)
	151	*style++ = 0;
	152
2b87da3b	153	if (authctxt->attempt++ == 0) {
63284fbb	154	/* setup auth context */
f7ed12f1	155	authctxt->pw = PRIVSEP(getpwnamallow(user));
f7ed12f1	156	if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
94ec8c6b	157	authctxt->valid = 1;
	158	debug2("input_userauth_request: setting up authctxt for %s", user);
	159	#ifdef USE_PAM
ad200abb	160	PRIVSEP(start_pam(authctxt->pw->pw_name));
94ec8c6b	161	#endif
	162	} else {
	163	log("input_userauth_request: illegal user %s", user);
04fc7a67	164	#ifdef USE_PAM
ad200abb	165	PRIVSEP(start_pam("NOUSER"));
04fc7a67	166	#endif
94ec8c6b	167	}
5f1f36b5	168	setproctitle("%s%s", authctxt->pw ? user : "unknown",
1853d1ef	169	use_privsep ? " [net]" : "");
94ec8c6b	170	authctxt->user = xstrdup(user);
94ec8c6b	171	authctxt->service = xstrdup(service);
2a6a054e	172	authctxt->style = style ? xstrdup(style) : NULL;
1853d1ef	173	if (use_privsep)
1853d1ef	174	mm_inform_authserv(service, style);
2a6a054e	175	} else if (strcmp(user, authctxt->user) != 0 \|\|
	176	strcmp(service, authctxt->service) != 0) {
	177	packet_disconnect("Change of username or service not allowed: "
	178	"(%s,%s) -> (%s,%s)",
	179	authctxt->user, authctxt->service, user, service);
a306f2dd	180	}
59c97189	181	/* reset state */
2f293d43	182	auth2_challenge_stop(authctxt);
59c97189	183	authctxt->postponed = 0;
9cd45ea4	184
59c97189	185	/* try to authenticate user */
94ec8c6b	186	m = authmethod_lookup(method);
	187	if (m != NULL) {
	188	debug2("input_userauth_request: try method %s", method);
	189	authenticated = m->userauth(authctxt);
9cd45ea4	190	}
d9cd3575	191	userauth_finish(authctxt, authenticated, method);
	192
	193	xfree(service);
	194	xfree(user);
	195	xfree(method);
	196	}
	197
	198	void
	199	userauth_finish(Authctxt authctxt, int authenticated, char method)
	200	{
4e81159c	201	char *methods;
4e81159c	202
59c97189	203	if (!authctxt->valid && authenticated)
	204	fatal("INTERNAL ERROR: authenticated invalid user %s",
	205	authctxt->user);
9cd45ea4	206
94ec8c6b	207	/* Special handling for root */
15853e93	208	if (authenticated && authctxt->pw->pw_uid == 0 &&
15853e93	209	!auth_root_allowed(method))
a306f2dd	210	authenticated = 0;
a306f2dd	211
a306f2dd	212	#ifdef USE_PAM
ad200abb	213	if (!use_privsep && authenticated && authctxt->user &&
ad200abb	214	!do_pam_account(authctxt->user, NULL))
9cd45ea4	215	authenticated = 0;
a306f2dd	216	#endif /* USE_PAM */
a306f2dd	217
94ec8c6b	218	/* Log before sending the reply */
59c97189	219	auth_log(authctxt, authenticated, method, " ssh2");
59c97189	220
4e81159c	221	if (authctxt->postponed)
	222	return;
	223
	224	/* XXX todo: check if multiple auth methods are needed */
	225	if (authenticated == 1) {
	226	/* turn off userauth */
6367063f	227	dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
4e81159c	228	packet_start(SSH2_MSG_USERAUTH_SUCCESS);
	229	packet_send();
	230	packet_write_wait();
	231	/* now we can break out */
	232	authctxt->success = 1;
	233	} else {
19e810f6	234	if (authctxt->failures++ > AUTH_FAIL_MAX) {
	235	#ifdef WITH_AIXAUTHENTICATE
	236	loginfailed(authctxt->user,
983784a1	237	get_canonical_hostname(options.verify_reverse_mapping),
19e810f6	238	"ssh");
19e810f6	239	#endif /* WITH_AIXAUTHENTICATE */
4e81159c	240	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
19e810f6	241	}
4e81159c	242	methods = authmethods_get();
	243	packet_start(SSH2_MSG_USERAUTH_FAILURE);
	244	packet_put_cstring(methods);
	245	packet_put_char(0); /* XXX partial success, unused */
	246	packet_send();
	247	packet_write_wait();
	248	xfree(methods);
	249	}
94ec8c6b	250	}
94ec8c6b	251
94a73cdc	252	char *
94a73cdc	253	auth2_read_banner(void)
eea39c02	254	{
	255	struct stat st;
	256	char *banner = NULL;
	257	off_t len, n;
	258	int fd;
	259
94a73cdc	260	if ((fd = open(options.banner, O_RDONLY)) == -1)
	261	return (NULL);
	262	if (fstat(fd, &st) == -1) {
	263	close(fd);
	264	return (NULL);
	265	}
eea39c02	266	len = st.st_size;
eea39c02	267	banner = xmalloc(len + 1);
94a73cdc	268	n = atomicio(read, fd, banner, len);
	269	close(fd);
	270
	271	if (n != len) {
	272	free(banner);
	273	return (NULL);
	274	}
eea39c02	275	banner[n] = '\0';
94a73cdc	276
	277	return (banner);
	278	}
	279
	280	static void
	281	userauth_banner(void)
	282	{
	283	char *banner = NULL;
	284
	285	if (options.banner == NULL \|\| (datafellows & SSH_BUG_BANNER))
	286	return;
	287
	288	if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
	289	goto done;
	290
eea39c02	291	packet_start(SSH2_MSG_USERAUTH_BANNER);
	292	packet_put_cstring(banner);
	293	packet_put_cstring(""); /* language, unused */
	294	packet_send();
	295	debug("userauth_banner: sent");
	296	done:
	297	if (banner)
	298	xfree(banner);
eea39c02	299	return;
eea39c02	300	}
94ec8c6b	301
396c147e	302	static int
94ec8c6b	303	userauth_none(Authctxt *authctxt)
a306f2dd	304	{
94ec8c6b	305	/* disable method "none", only allowed one time */
	306	Authmethod *m = authmethod_lookup("none");
	307	if (m != NULL)
	308	m->enabled = NULL;
95500969	309	packet_check_eom();
2b87da3b	310	userauth_banner();
4d33e531	311
94ec8c6b	312	if (authctxt->valid == 0)
94ec8c6b	313	return(0);
63284fbb	314
	315	#ifdef HAVE_CYGWIN
	316	if (check_nt_auth(1, authctxt->pw) == 0)
	317	return(0);
94ec8c6b	318	#endif
1853d1ef	319	return PRIVSEP(auth_password(authctxt, ""));
a306f2dd	320	}
94ec8c6b	321
396c147e	322	static int
94ec8c6b	323	userauth_passwd(Authctxt *authctxt)
a306f2dd	324	{
	325	char *password;
	326	int authenticated = 0;
	327	int change;
1e3b8b07	328	u_int len;
a306f2dd	329	change = packet_get_char();
	330	if (change)
	331	log("password change not supported");
	332	password = packet_get_string(&len);
95500969	333	packet_check_eom();
63284fbb	334	if (authctxt->valid &&
	335	#ifdef HAVE_CYGWIN
	336	check_nt_auth(1, authctxt->pw) &&
94ec8c6b	337	#endif
1853d1ef	338	PRIVSEP(auth_password(authctxt, password)) == 1)
63284fbb	339	authenticated = 1;
a306f2dd	340	memset(password, 0, len);
	341	xfree(password);
	342	return authenticated;
	343	}
94ec8c6b	344
396c147e	345	static int
94ec8c6b	346	userauth_kbdint(Authctxt *authctxt)
	347	{
	348	int authenticated = 0;
5ba55ada	349	char lang, devs;
94ec8c6b	350
	351	lang = packet_get_string(NULL);
	352	devs = packet_get_string(NULL);
95500969	353	packet_check_eom();
94ec8c6b	354
5ba55ada	355	debug("keyboard-interactive devs %s", devs);
59c97189	356
5ba55ada	357	if (options.challenge_response_authentication)
d464095c	358	authenticated = auth2_challenge(authctxt, devs);
59c97189	359
8c9fe09e	360	#ifdef USE_PAM
10f72868	361	if (authenticated == 0 && options.pam_authentication_via_kbd_int)
8c9fe09e	362	authenticated = auth2_pam(authctxt);
94ec8c6b	363	#endif
94ec8c6b	364	xfree(devs);
5ba55ada	365	xfree(lang);
94ec8c6b	366	#ifdef HAVE_CYGWIN
e9571a2c	367	if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b	368	return(0);
	369	#endif
	370	return authenticated;
	371	}
	372
396c147e	373	static int
94ec8c6b	374	userauth_pubkey(Authctxt *authctxt)
a306f2dd	375	{
a306f2dd	376	Buffer b;
67fa09f5	377	Key *key = NULL;
c66f9d0e	378	char *pkalg;
c66f9d0e	379	u_char pkblob, sig;
1e3b8b07	380	u_int alen, blen, slen;
fa08c86b	381	int have_sig, pktype;
a306f2dd	382	int authenticated = 0;
a306f2dd	383
94ec8c6b	384	if (!authctxt->valid) {
94ec8c6b	385	debug2("userauth_pubkey: disabled because of invalid user");
a306f2dd	386	return 0;
	387	}
	388	have_sig = packet_get_char();
cbc5abf9	389	if (datafellows & SSH_BUG_PKAUTH) {
	390	debug2("userauth_pubkey: SSH_BUG_PKAUTH");
	391	/* no explicit pkalg given */
	392	pkblob = packet_get_string(&blen);
	393	buffer_init(&b);
	394	buffer_append(&b, pkblob, blen);
	395	/* so we have to extract the pkalg from the pkblob */
	396	pkalg = buffer_get_string(&b, &alen);
	397	buffer_free(&b);
	398	} else {
	399	pkalg = packet_get_string(&alen);
	400	pkblob = packet_get_string(&blen);
	401	}
fa08c86b	402	pktype = key_type_from_name(pkalg);
fa08c86b	403	if (pktype == KEY_UNSPEC) {
cbc5abf9	404	/* this is perfectly legal */
67fa09f5	405	log("userauth_pubkey: unsupported public key algorithm: %s",
	406	pkalg);
	407	goto done;
a306f2dd	408	}
fa08c86b	409	key = key_from_blob(pkblob, blen);
67fa09f5	410	if (key == NULL) {
	411	error("userauth_pubkey: cannot decode key: %s", pkalg);
	412	goto done;
	413	}
	414	if (key->type != pktype) {
	415	error("userauth_pubkey: type mismatch for decoded key "
	416	"(received %d, expected %d)", key->type, pktype);
	417	goto done;
	418	}
	419	if (have_sig) {
	420	sig = packet_get_string(&slen);
	421	packet_check_eom();
	422	buffer_init(&b);
	423	if (datafellows & SSH_OLD_SESSIONID) {
	424	buffer_append(&b, session_id2, session_id2_len);
	425	} else {
	426	buffer_put_string(&b, session_id2, session_id2_len);
	427	}
	428	/* reconstruct packet */
	429	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	430	buffer_put_cstring(&b, authctxt->user);
	431	buffer_put_cstring(&b,
	432	datafellows & SSH_BUG_PKSERVICE ?
	433	"ssh-userauth" :
	434	authctxt->service);
	435	if (datafellows & SSH_BUG_PKAUTH) {
	436	buffer_put_char(&b, have_sig);
	437	} else {
	438	buffer_put_cstring(&b, "publickey");
	439	buffer_put_char(&b, have_sig);
	440	buffer_put_cstring(&b, pkalg);
	441	}
	442	buffer_put_string(&b, pkblob, blen);
fa08c86b	443	#ifdef DEBUG_PK
67fa09f5	444	buffer_dump(&b);
a306f2dd	445	#endif
67fa09f5	446	/* test for correct signature */
1853d1ef	447	authenticated = 0;
	448	if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
	449	PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
	450	buffer_len(&b))) == 1)
63284fbb	451	authenticated = 1;
67fa09f5	452	buffer_clear(&b);
	453	xfree(sig);
	454	} else {
	455	debug("test whether pkalg/pkblob are acceptable");
	456	packet_check_eom();
	457
	458	/* XXX fake reply and always send PK_OK ? */
	459	/*
	460	* XXX this allows testing whether a user is allowed
	461	* to login: if you happen to have a valid pubkey this
	462	* message is sent. the message is NEVER sent at all
	463	* if a user is not allowed to login. is this an
	464	* issue? -markus
	465	*/
1853d1ef	466	if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
67fa09f5	467	packet_start(SSH2_MSG_USERAUTH_PK_OK);
	468	packet_put_string(pkalg, alen);
	469	packet_put_string(pkblob, blen);
	470	packet_send();
	471	packet_write_wait();
	472	authctxt->postponed = 1;
a306f2dd	473	}
a306f2dd	474	}
67fa09f5	475	if (authenticated != 1)
	476	auth_clear_options();
	477	done:
fa08c86b	478	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
67fa09f5	479	if (key != NULL)
67fa09f5	480	key_free(key);
a306f2dd	481	xfree(pkalg);
a306f2dd	482	xfree(pkblob);
94ec8c6b	483	#ifdef HAVE_CYGWIN
e9571a2c	484	if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b	485	return(0);
94ec8c6b	486	#endif
a306f2dd	487	return authenticated;
	488	}
	489
396c147e	490	static int
8002af61	491	userauth_hostbased(Authctxt *authctxt)
	492	{
	493	Buffer b;
67fa09f5	494	Key *key = NULL;
c66f9d0e	495	char pkalg, cuser, chost, service;
c66f9d0e	496	u_char pkblob, sig;
8002af61	497	u_int alen, blen, slen;
	498	int pktype;
	499	int authenticated = 0;
	500
	501	if (!authctxt->valid) {
	502	debug2("userauth_hostbased: disabled because of invalid user");
	503	return 0;
	504	}
	505	pkalg = packet_get_string(&alen);
	506	pkblob = packet_get_string(&blen);
	507	chost = packet_get_string(NULL);
	508	cuser = packet_get_string(NULL);
	509	sig = packet_get_string(&slen);
	510
	511	debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
	512	cuser, chost, pkalg, slen);
	513	#ifdef DEBUG_PK
	514	debug("signature:");
	515	buffer_init(&b);
	516	buffer_append(&b, sig, slen);
	517	buffer_dump(&b);
	518	buffer_free(&b);
	519	#endif
	520	pktype = key_type_from_name(pkalg);
	521	if (pktype == KEY_UNSPEC) {
	522	/* this is perfectly legal */
	523	log("userauth_hostbased: unsupported "
	524	"public key algorithm: %s", pkalg);
	525	goto done;
	526	}
	527	key = key_from_blob(pkblob, blen);
	528	if (key == NULL) {
67fa09f5	529	error("userauth_hostbased: cannot decode key: %s", pkalg);
	530	goto done;
	531	}
	532	if (key->type != pktype) {
	533	error("userauth_hostbased: type mismatch for decoded key "
	534	"(received %d, expected %d)", key->type, pktype);
8002af61	535	goto done;
8002af61	536	}
8dddf799	537	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
8dddf799	538	authctxt->service;
8002af61	539	buffer_init(&b);
8dddf799	540	buffer_put_string(&b, session_id2, session_id2_len);
8002af61	541	/* reconstruct packet */
	542	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	543	buffer_put_cstring(&b, authctxt->user);
8dddf799	544	buffer_put_cstring(&b, service);
8002af61	545	buffer_put_cstring(&b, "hostbased");
	546	buffer_put_string(&b, pkalg, alen);
	547	buffer_put_string(&b, pkblob, blen);
	548	buffer_put_cstring(&b, chost);
	549	buffer_put_cstring(&b, cuser);
	550	#ifdef DEBUG_PK
	551	buffer_dump(&b);
	552	#endif
	553	/* test for allowed key and correct signature */
1853d1ef	554	authenticated = 0;
	555	if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
	556	PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
	557	buffer_len(&b))) == 1)
63284fbb	558	authenticated = 1;
8002af61	559
8002af61	560	buffer_clear(&b);
8002af61	561	done:
8002af61	562	debug2("userauth_hostbased: authenticated %d", authenticated);
67fa09f5	563	if (key != NULL)
67fa09f5	564	key_free(key);
8002af61	565	xfree(pkalg);
	566	xfree(pkblob);
	567	xfree(cuser);
	568	xfree(chost);
	569	xfree(sig);
	570	return authenticated;
	571	}
	572
94ec8c6b	573	/* get current user */
a306f2dd	574
	575	struct passwd*
	576	auth_get_user(void)
	577	{
94ec8c6b	578	return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
a306f2dd	579	}
a306f2dd	580
94ec8c6b	581	#define DELIM ","
94ec8c6b	582
ffb215be	583	static char *
94ec8c6b	584	authmethods_get(void)
a306f2dd	585	{
3469eac4	586	Buffer b;
94ec8c6b	587	char *list;
01c24737	588	int i;
94ec8c6b	589
3469eac4	590	buffer_init(&b);
01c24737	591	for (i = 0; authmethods[i] != NULL; i++) {
01c24737	592	if (strcmp(authmethods[i]->name, "none") == 0)
94ec8c6b	593	continue;
01c24737	594	if (authmethods[i]->enabled != NULL &&
01c24737	595	*(authmethods[i]->enabled) != 0) {
3469eac4	596	if (buffer_len(&b) > 0)
3469eac4	597	buffer_append(&b, ",", 1);
01c24737	598	buffer_append(&b, authmethods[i]->name,
01c24737	599	strlen(authmethods[i]->name));
a306f2dd	600	}
a306f2dd	601	}
3469eac4	602	buffer_append(&b, "\0", 1);
	603	list = xstrdup(buffer_ptr(&b));
	604	buffer_free(&b);
94ec8c6b	605	return list;
	606	}
	607
396c147e	608	static Authmethod *
94ec8c6b	609	authmethod_lookup(const char *name)
94ec8c6b	610	{
01c24737	611	int i;
01c24737	612
94ec8c6b	613	if (name != NULL)
01c24737	614	for (i = 0; authmethods[i] != NULL; i++)
	615	if (authmethods[i]->enabled != NULL &&
	616	*(authmethods[i]->enabled) != 0 &&
	617	strcmp(name, authmethods[i]->name) == 0)
	618	return authmethods[i];
	619	debug2("Unrecognized authentication method name: %s",
	620	name ? name : "NULL");
94ec8c6b	621	return NULL;
a306f2dd	622	}