[gssapi-openssh.git] / openssh / auth1.c

/*
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"
RCSID("$OpenBSD: auth1.c,v 1.62 2005/07/16 01:35:24 djm Exp $");

#include "xmalloc.h"
#include "rsa.h"
#include "ssh1.h"
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "servconf.h"
#include "compat.h"
#include "auth.h"
#include "channels.h"
#include "session.h"
#include "uidswap.h"
#include "monitor_wrap.h"
#include "buffer.h"

/* import */
extern ServerOptions options;
extern Buffer loginmsg;

static int auth1_process_password(Authctxt *, char *, size_t);
static int auth1_process_rsa(Authctxt *, char *, size_t);
static int auth1_process_rhosts_rsa(Authctxt *, char *, size_t);
static int auth1_process_tis_challenge(Authctxt *, char *, size_t);
static int auth1_process_tis_response(Authctxt *, char *, size_t);

static char *client_user = NULL;    /* Used to fill in remote user for PAM */

struct AuthMethod1 {
	int type;
	char *name;
	int *enabled;
	int (*method)(Authctxt *, char *, size_t);
};

const struct AuthMethod1 auth1_methods[] = {
	{
		SSH_CMSG_AUTH_PASSWORD, "password",
		&options.password_authentication, auth1_process_password
	},
	{
		SSH_CMSG_AUTH_RSA, "rsa",
		&options.rsa_authentication, auth1_process_rsa
	},
	{
		SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
		&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	},
	{
		SSH_CMSG_AUTH_TIS, "challenge-response",
		&options.challenge_response_authentication,
		auth1_process_tis_challenge
	},
	{
		SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
		&options.challenge_response_authentication,
		auth1_process_tis_response
	},
	{ -1, NULL, NULL, NULL}
};

static const struct AuthMethod1
*lookup_authmethod1(int type)
{
	int i;

	for(i = 0; auth1_methods[i].name != NULL; i++)
		if (auth1_methods[i].type == type)
			return (&(auth1_methods[i]));

	return (NULL);
}

static char *
get_authname(int type)
{
	const struct AuthMethod1 *a;
	static char buf[64];

	if ((a = lookup_authmethod1(type)) != NULL)
		return (a->name);
	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	return (buf);
}

static int
auth1_process_password(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	char *password;
	u_int dlen;

	/*
	 * Read user password.  It is in plain text, but was
	 * transmitted over the encrypted channel so it is
	 * not visible to an outside observer.
	 */
	password = packet_get_string(&dlen);
	packet_check_eom();

	/* Try authentication with the password. */
	authenticated = PRIVSEP(auth_password(authctxt, password));

	memset(password, 0, dlen);
	xfree(password);

	return (authenticated);
}

static int
auth1_process_rsa(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	BIGNUM *n;

	/* RSA authentication requested. */
	if ((n = BN_new()) == NULL)
		fatal("do_authloop: BN_new failed");
	packet_get_bignum(n);
	packet_check_eom();
	authenticated = auth_rsa(authctxt, n);
	BN_clear_free(n);

	return (authenticated);
}

static int
auth1_process_rhosts_rsa(Authctxt *authctxt, char *info, size_t infolen)
{
	int keybits, authenticated = 0;
	u_int bits;
	Key *client_host_key;
	u_int ulen;

	/*
	 * Get client user name.  Note that we just have to
	 * trust the client; root on the client machine can
	 * claim to be any user.
	 */
	client_user = packet_get_string(&ulen);

	/* Get the client host key. */
	client_host_key = key_new(KEY_RSA1);
	bits = packet_get_int();
	packet_get_bignum(client_host_key->rsa->e);
	packet_get_bignum(client_host_key->rsa->n);

	keybits = BN_num_bits(client_host_key->rsa->n);
	if (keybits < 0 || bits != (u_int)keybits) {
		verbose("Warning: keysize mismatch for client_host_key: "
		    "actual %d, announced %d",
		    BN_num_bits(client_host_key->rsa->n), bits);
	}
	packet_check_eom();

	authenticated = auth_rhosts_rsa(authctxt, client_user,
	    client_host_key);
	key_free(client_host_key);

	snprintf(info, infolen, " ruser %.100s", client_user);

	return (authenticated);
}

static int
auth1_process_tis_challenge(Authctxt *authctxt, char *info, size_t infolen)
{
	char *challenge;

	if ((challenge = get_challenge(authctxt)) == NULL)
		return (0);

	debug("sending challenge '%s'", challenge);
	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	packet_put_cstring(challenge);
	xfree(challenge);
	packet_send();
	packet_write_wait();

	return (-1);
}

static int
auth1_process_tis_response(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	char *response;
	u_int dlen;

	response = packet_get_string(&dlen);
	packet_check_eom();
	authenticated = verify_response(authctxt, response);
	memset(response, 'r', dlen);
	xfree(response);

	return (authenticated);
}

/*
 * read packets, try to authenticate the user and
 * return only if authentication is successful
 */
static void
do_authloop(Authctxt *authctxt)
{
	int authenticated = 0;
	char info[1024];
	int prev = 0, type = 0;
	const struct AuthMethod1 *meth;

	debug("Attempting authentication for %s%.100s.",
	    authctxt->valid ? "" : "invalid user ", authctxt->user);

	/* If the user has no password, accept authentication immediately. */
	if (options.password_authentication &&
#ifdef KRB5
	    (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
	    PRIVSEP(auth_password(authctxt, ""))) {
#ifdef USE_PAM
		if (options.use_pam && (PRIVSEP(do_pam_account())))
#endif
		{
			auth_log(authctxt, 1, "without authentication", "");
			return;
		}
	}

	/* Indicate that authentication is needed. */
	packet_start(SSH_SMSG_FAILURE);
	packet_send();
	packet_write_wait();

	for (;;) {
		/* default to fail */
		authenticated = 0;

		info[0] = '\0';

		/* Get a packet from the client. */
		prev = type;
		type = packet_read();

		/*
		 * If we started challenge-response authentication but the
		 * next packet is not a response to our challenge, release
		 * the resources allocated by get_challenge() (which would
		 * normally have been released by verify_response() had we
		 * received such a response)
		 */
		if (prev == SSH_CMSG_AUTH_TIS &&
		    type != SSH_CMSG_AUTH_TIS_RESPONSE)
			abandon_challenge_response(authctxt);

		if ((meth = lookup_authmethod1(type)) == NULL) {
			logit("Unknown message during authentication: "
			    "type %d", type);
			goto skip;
		}

		if (!*(meth->enabled)) {
			verbose("%s authentication disabled.", meth->name);
			goto skip;
		}

		authenticated = meth->method(authctxt, info, sizeof(info));
		if (authenticated == -1)
			continue; /* "postponed" */

#ifdef BSD_AUTH
		if (authctxt->as) {
			auth_close(authctxt->as);
			authctxt->as = NULL;
		}
#endif
		if (!authctxt->valid && authenticated)
			fatal("INTERNAL ERROR: authenticated invalid user %s",
			    authctxt->user);

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

#ifdef HAVE_CYGWIN
		if (authenticated &&
		    !check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
		    authctxt->pw)) {
			packet_disconnect("Authentication rejected for uid %d.",
			    authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
			authenticated = 0;
		}
#else
		/* Special handling for root */
		if (authenticated && authctxt->pw->pw_uid == 0 &&
		    !auth_root_allowed(meth->name)) {
 			authenticated = 0;
# ifdef SSH_AUDIT_EVENTS
			PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
# endif
		}
#endif

#ifdef USE_PAM
		if (options.use_pam && authenticated &&
		    !PRIVSEP(do_pam_account())) {
			char *msg;
			size_t len;

			error("Access denied for user %s by PAM account "
			    "configuration", authctxt->user);
			len = buffer_len(&loginmsg);
			buffer_append(&loginmsg, "\0", 1);
			msg = buffer_ptr(&loginmsg);
			/* strip trailing newlines */
			if (len > 0)
				while (len > 0 && msg[--len] == '\n')
					msg[len] = '\0';
			else
				msg = "Access denied.";
			packet_disconnect(msg);
		}
#endif

 skip:
		/* Log before sending the reply */
		auth_log(authctxt, authenticated, get_authname(type), info);

		if (client_user != NULL) {
			xfree(client_user);
			client_user = NULL;
		}

		if (authenticated)
			return;

		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);
		}

		packet_start(SSH_SMSG_FAILURE);
		packet_send();
		packet_write_wait();
	}
}

/*
 * Performs authentication of an incoming connection.  Session key has already
 * been exchanged and encryption is enabled.
 */
void
do_authentication(Authctxt *authctxt)
{
	u_int ulen;
	char *user, *style = NULL;

	/* Get the name of the user that we wish to log in as. */
	packet_read_expect(SSH_CMSG_USER);

	/* Get the user name. */
	user = packet_get_string(&ulen);
	packet_check_eom();

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

	authctxt->user = user;
	authctxt->style = style;

	/* Verify that the user is a valid user. */
	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
		authctxt->valid = 1;
	else {
		debug("do_authentication: invalid user %s", user);
		authctxt->pw = fakepw();
	}

	setproctitle("%s%s", authctxt->valid ? user : "unknown",
	    use_privsep ? " [net]" : "");

#ifdef USE_PAM
	if (options.use_pam)
		PRIVSEP(start_pam(authctxt));
#endif

	/*
	 * If we are not running as root, the user must have the same uid as
	 * the server.
	 */
#ifndef HAVE_CYGWIN
	if (!use_privsep && getuid() != 0 && authctxt->pw &&
	    authctxt->pw->pw_uid != getuid())
		packet_disconnect("Cannot change user when server not running as root.");
#endif

	/*
	 * Loop until the user has been authenticated or the connection is
	 * closed, do_authloop() returns only if authentication is successful
	 */
	do_authloop(authctxt);

	/* The user has been authenticated and accepted. */
	packet_start(SSH_SMSG_SUCCESS);
	packet_send();
	packet_write_wait();
}
Commit	Line	Data
3c0ef626	1	/*
	2	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	3	* All rights reserved
	4	*
	5	* As far as I am concerned, the code I have written for this software
	6	* can be used freely for any purpose. Any derived versions of this
	7	* software must be clearly marked as such, and if the derived work is
	8	* incompatible with the protocol description in the RFC file, it must be
	9	* called by a name other than "ssh" or "Secure Shell".
	10	*/
	11
	12	#include "includes.h"
2ce0bfe4	13	RCSID("$OpenBSD: auth1.c,v 1.62 2005/07/16 01:35:24 djm Exp $");
3c0ef626	14
	15	#include "xmalloc.h"
	16	#include "rsa.h"
	17	#include "ssh1.h"
	18	#include "packet.h"
	19	#include "buffer.h"
3c0ef626	20	#include "log.h"
	21	#include "servconf.h"
	22	#include "compat.h"
	23	#include "auth.h"
1e608e42	24	#include "channels.h"
3c0ef626	25	#include "session.h"
3c0ef626	26	#include "uidswap.h"
510132b6	27	#include "monitor_wrap.h"
dfddba3d	28	#include "buffer.h"
3c0ef626	29
	30	/* import */
	31	extern ServerOptions options;
dfddba3d	32	extern Buffer loginmsg;
3c0ef626	33
2ce0bfe4	34	static int auth1_process_password(Authctxt , char , size_t);
	35	static int auth1_process_rsa(Authctxt , char , size_t);
	36	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	37	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	38	static int auth1_process_tis_response(Authctxt , char , size_t);
	39
	40	static char client_user = NULL; / Used to fill in remote user for PAM */
	41
	42	struct AuthMethod1 {
	43	int type;
	44	char *name;
	45	int *enabled;
	46	int (method)(Authctxt , char *, size_t);
	47	};
	48
	49	const struct AuthMethod1 auth1_methods[] = {
	50	{
	51	SSH_CMSG_AUTH_PASSWORD, "password",
	52	&options.password_authentication, auth1_process_password
	53	},
	54	{
	55	SSH_CMSG_AUTH_RSA, "rsa",
	56	&options.rsa_authentication, auth1_process_rsa
	57	},
	58	{
	59	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	60	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	61	},
	62	{
	63	SSH_CMSG_AUTH_TIS, "challenge-response",
	64	&options.challenge_response_authentication,
	65	auth1_process_tis_challenge
	66	},
	67	{
	68	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	69	&options.challenge_response_authentication,
	70	auth1_process_tis_response
	71	},
	72	{ -1, NULL, NULL, NULL}
	73	};
	74
	75	static const struct AuthMethod1
	76	*lookup_authmethod1(int type)
	77	{
	78	int i;
	79
	80	for(i = 0; auth1_methods[i].name != NULL; i++)
	81	if (auth1_methods[i].type == type)
	82	return (&(auth1_methods[i]));
	83
	84	return (NULL);
	85	}
	86
3c0ef626	87	static char *
	88	get_authname(int type)
	89	{
2ce0bfe4	90	const struct AuthMethod1 *a;
	91	static char buf[64];
	92
	93	if ((a = lookup_authmethod1(type)) != NULL)
	94	return (a->name);
	95	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	96	return (buf);
	97	}
	98
	99	static int
	100	auth1_process_password(Authctxt authctxt, char info, size_t infolen)
	101	{
	102	int authenticated = 0;
	103	char *password;
	104	u_int dlen;
	105
	106	/*
	107	* Read user password. It is in plain text, but was
	108	* transmitted over the encrypted channel so it is
	109	* not visible to an outside observer.
	110	*/
	111	password = packet_get_string(&dlen);
	112	packet_check_eom();
	113
	114	/* Try authentication with the password. */
	115	authenticated = PRIVSEP(auth_password(authctxt, password));
	116
	117	memset(password, 0, dlen);
	118	xfree(password);
	119
	120	return (authenticated);
	121	}
	122
	123	static int
	124	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	125	{
	126	int authenticated = 0;
	127	BIGNUM *n;
	128
	129	/* RSA authentication requested. */
	130	if ((n = BN_new()) == NULL)
	131	fatal("do_authloop: BN_new failed");
	132	packet_get_bignum(n);
	133	packet_check_eom();
	134	authenticated = auth_rsa(authctxt, n);
	135	BN_clear_free(n);
	136
	137	return (authenticated);
	138	}
	139
	140	static int
	141	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	142	{
	143	int keybits, authenticated = 0;
	144	u_int bits;
	145	Key *client_host_key;
	146	u_int ulen;
	147
	148	/*
	149	* Get client user name. Note that we just have to
	150	* trust the client; root on the client machine can
	151	* claim to be any user.
	152	*/
	153	client_user = packet_get_string(&ulen);
154
155	/* Get the client host key. */
156	client_host_key = key_new(KEY_RSA1);
157	bits = packet_get_int();
158	packet_get_bignum(client_host_key->rsa->e);
159	packet_get_bignum(client_host_key->rsa->n);
160
161	keybits = BN_num_bits(client_host_key->rsa->n);
162	if (keybits < 0 \|\| bits != (u_int)keybits) {
163	verbose("Warning: keysize mismatch for client_host_key: "
164	"actual %d, announced %d",
165	BN_num_bits(client_host_key->rsa->n), bits);
3c0ef626	166	}
2ce0bfe4	167	packet_check_eom();
	168
	169	authenticated = auth_rhosts_rsa(authctxt, client_user,
	170	client_host_key);
	171	key_free(client_host_key);
	172
	173	snprintf(info, infolen, " ruser %.100s", client_user);
	174
	175	return (authenticated);
	176	}
	177
	178	static int
	179	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	180	{
	181	char *challenge;
	182
	183	if ((challenge = get_challenge(authctxt)) == NULL)
	184	return (0);
	185
	186	debug("sending challenge '%s'", challenge);
	187	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	188	packet_put_cstring(challenge);
	189	xfree(challenge);
	190	packet_send();
	191	packet_write_wait();
	192
	193	return (-1);
	194	}
	195
	196	static int
	197	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	198	{
	199	int authenticated = 0;
	200	char *response;
	201	u_int dlen;
	202
	203	response = packet_get_string(&dlen);
	204	packet_check_eom();
	205	authenticated = verify_response(authctxt, response);
	206	memset(response, 'r', dlen);
	207	xfree(response);
	208
	209	return (authenticated);
3c0ef626	210	}
	211
	212	/*
	213	* read packets, try to authenticate the user and
	214	* return only if authentication is successful
	215	*/
	216	static void
	217	do_authloop(Authctxt *authctxt)
	218	{
	219	int authenticated = 0;
3c0ef626	220	char info[1024];
2ce0bfe4	221	int prev = 0, type = 0;
2ce0bfe4	222	const struct AuthMethod1 *meth;
3c0ef626	223
3c0ef626	224	debug("Attempting authentication for %s%.100s.",
7e82606e	225	authctxt->valid ? "" : "invalid user ", authctxt->user);
3c0ef626	226
	227	/* If the user has no password, accept authentication immediately. */
	228	if (options.password_authentication &&
7cac2b65	229	#ifdef KRB5
3c0ef626	230	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
3c0ef626	231	#endif
510132b6	232	PRIVSEP(auth_password(authctxt, ""))) {
7e82606e	233	#ifdef USE_PAM
	234	if (options.use_pam && (PRIVSEP(do_pam_account())))
	235	#endif
	236	{
	237	auth_log(authctxt, 1, "without authentication", "");
	238	return;
	239	}
3c0ef626	240	}
	241
	242	/* Indicate that authentication is needed. */
	243	packet_start(SSH_SMSG_FAILURE);
	244	packet_send();
	245	packet_write_wait();
	246
3c0ef626	247	for (;;) {
	248	/* default to fail */
	249	authenticated = 0;
	250
	251	info[0] = '\0';
	252
	253	/* Get a packet from the client. */
7cac2b65	254	prev = type;
1e608e42	255	type = packet_read();
3c0ef626	256
7cac2b65	257	/*
	258	* If we started challenge-response authentication but the
	259	* next packet is not a response to our challenge, release
	260	* the resources allocated by get_challenge() (which would
	261	* normally have been released by verify_response() had we
	262	* received such a response)
	263	*/
	264	if (prev == SSH_CMSG_AUTH_TIS &&
	265	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	266	abandon_challenge_response(authctxt);
	267
2ce0bfe4	268	if ((meth = lookup_authmethod1(type)) == NULL) {
	269	logit("Unknown message during authentication: "
	270	"type %d", type);
	271	goto skip;
	272	}
	273
	274	if (!*(meth->enabled)) {
	275	verbose("%s authentication disabled.", meth->name);
	276	goto skip;
3c0ef626	277	}
2ce0bfe4	278
	279	authenticated = meth->method(authctxt, info, sizeof(info));
	280	if (authenticated == -1)
	281	continue; /* "postponed" */
	282
3c0ef626	283	#ifdef BSD_AUTH
	284	if (authctxt->as) {
	285	auth_close(authctxt->as);
	286	authctxt->as = NULL;
	287	}
	288	#endif
	289	if (!authctxt->valid && authenticated)
	290	fatal("INTERNAL ERROR: authenticated invalid user %s",
	291	authctxt->user);
	292
d03f4262	293	#ifdef _UNICOS
d03f4262	294	if (authenticated && cray_access_denied(authctxt->user)) {
	295	authenticated = 0;
	296	fatal("Access denied for user %s.",authctxt->user);
	297	}
	298	#endif /* _UNICOS */
	299
3c0ef626	300	#ifdef HAVE_CYGWIN
3c0ef626	301	if (authenticated &&
2ce0bfe4	302	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
7e82606e	303	authctxt->pw)) {
3c0ef626	304	packet_disconnect("Authentication rejected for uid %d.",
7e82606e	305	authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
3c0ef626	306	authenticated = 0;
	307	}
	308	#else
	309	/* Special handling for root */
bfe49944	310	if (authenticated && authctxt->pw->pw_uid == 0 &&
2ce0bfe4	311	!auth_root_allowed(meth->name)) {
2ce0bfe4	312	authenticated = 0;
dfddba3d	313	# ifdef SSH_AUDIT_EVENTS
	314	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
	315	# endif
	316	}
3c0ef626	317	#endif
7cac2b65	318
3c0ef626	319	#ifdef USE_PAM
540d72c3	320	if (options.use_pam && authenticated &&
dfddba3d	321	!PRIVSEP(do_pam_account())) {
	322	char *msg;
	323	size_t len;
	324
	325	error("Access denied for user %s by PAM account "
2ce0bfe4	326	"configuration", authctxt->user);
dfddba3d	327	len = buffer_len(&loginmsg);
	328	buffer_append(&loginmsg, "\0", 1);
	329	msg = buffer_ptr(&loginmsg);
	330	/* strip trailing newlines */
	331	if (len > 0)
	332	while (len > 0 && msg[--len] == '\n')
	333	msg[len] = '\0';
	334	else
	335	msg = "Access denied.";
	336	packet_disconnect(msg);
	337	}
3c0ef626	338	#endif
3c0ef626	339
2ce0bfe4	340	skip:
3c0ef626	341	/* Log before sending the reply */
	342	auth_log(authctxt, authenticated, get_authname(type), info);
	343
	344	if (client_user != NULL) {
	345	xfree(client_user);
	346	client_user = NULL;
	347	}
	348
	349	if (authenticated)
	350	return;
	351
dfddba3d	352	if (authctxt->failures++ > options.max_authtries) {
	353	#ifdef SSH_AUDIT_EVENTS
	354	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
	355	#endif
3c0ef626	356	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
dfddba3d	357	}
3c0ef626	358
	359	packet_start(SSH_SMSG_FAILURE);
	360	packet_send();
	361	packet_write_wait();
	362	}
	363	}
	364
	365	/*
	366	* Performs authentication of an incoming connection. Session key has already
	367	* been exchanged and encryption is enabled.
	368	*/
540d72c3	369	void
540d72c3	370	do_authentication(Authctxt *authctxt)
3c0ef626	371	{
3c0ef626	372	u_int ulen;
510132b6	373	char user, style = NULL;
3c0ef626	374
3c0ef626	375	/* Get the name of the user that we wish to log in as. */
1e608e42	376	packet_read_expect(SSH_CMSG_USER);
3c0ef626	377
	378	/* Get the user name. */
	379	user = packet_get_string(&ulen);
1e608e42	380	packet_check_eom();
3c0ef626	381
	382	if ((style = strchr(user, ':')) != NULL)
	383	*style++ = '\0';
	384
3c0ef626	385	authctxt->user = user;
	386	authctxt->style = style;
	387
	388	/* Verify that the user is a valid user. */
510132b6	389	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
3c0ef626	390	authctxt->valid = 1;
7cac2b65	391	else {
7e82606e	392	debug("do_authentication: invalid user %s", user);
7cac2b65	393	authctxt->pw = fakepw();
7cac2b65	394	}
3c0ef626	395
7e82606e	396	setproctitle("%s%s", authctxt->valid ? user : "unknown",
510132b6	397	use_privsep ? " [net]" : "");
3c0ef626	398
3c0ef626	399	#ifdef USE_PAM
7cac2b65	400	if (options.use_pam)
12a403af	401	PRIVSEP(start_pam(authctxt));
3c0ef626	402	#endif
	403
	404	/*
	405	* If we are not running as root, the user must have the same uid as
2ce0bfe4	406	* the server.
3c0ef626	407	*/
3c0ef626	408	#ifndef HAVE_CYGWIN
510132b6	409	if (!use_privsep && getuid() != 0 && authctxt->pw &&
510132b6	410	authctxt->pw->pw_uid != getuid())
3c0ef626	411	packet_disconnect("Cannot change user when server not running as root.");
	412	#endif
	413
	414	/*
	415	* Loop until the user has been authenticated or the connection is
	416	* closed, do_authloop() returns only if authentication is successful
	417	*/
	418	do_authloop(authctxt);
	419
	420	/* The user has been authenticated and accepted. */
	421	packet_start(SSH_SMSG_SUCCESS);
	422	packet_send();
	423	packet_write_wait();
3c0ef626	424	}