[openssh.git] / auth1.c

/* $OpenBSD: auth1.c,v 1.73 2008/07/04 23:30:16 djm Exp $ */
/*
 * 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"

#include <sys/types.h>

#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <pwd.h>

#include "openbsd-compat/sys-queue.h"
#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 "key.h"
#include "hostfile.h"
#include "auth.h"
#include "channels.h"
#include "session.h"
#include "uidswap.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#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);
}

/*ARGSUSED*/
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);
}

/*ARGSUSED*/
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);
}

/*ARGSUSED*/
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);
}

/*ARGSUSED*/
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);
}

/*ARGSUSED*/
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 (authctxt->failures >= options.max_authtries)
			goto skip;
		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 */

#ifndef HAVE_CYGWIN
		/* 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("%s", 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
71709bcd	1	/* $OpenBSD: auth1.c,v 1.73 2008/07/04 23:30:16 djm Exp $ */
a306f2dd	2	/*
	3	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	4	* All rights reserved
bcbf86ec	5	*
	6	* As far as I am concerned, the code I have written for this software
	7	* can be used freely for any purpose. Any derived versions of this
	8	* software must be clearly marked as such, and if the derived work is
	9	* incompatible with the protocol description in the RFC file, it must be
	10	* called by a name other than "ssh" or "Secure Shell".
a306f2dd	11	*/
	12
	13	#include "includes.h"
94ec8c6b	14
67514848	15	#include <sys/types.h>
67514848	16
24436b92	17	#include <stdarg.h>
cf851879	18	#include <stdio.h>
00146caa	19	#include <string.h>
67514848	20	#include <unistd.h>
31652869	21	#include <pwd.h>
67514848	22
3593bdc0	23	#include "openbsd-compat/sys-queue.h"
a306f2dd	24	#include "xmalloc.h"
a306f2dd	25	#include "rsa.h"
42f11eb2	26	#include "ssh1.h"
a306f2dd	27	#include "packet.h"
a306f2dd	28	#include "buffer.h"
42f11eb2	29	#include "log.h"
a306f2dd	30	#include "servconf.h"
a306f2dd	31	#include "compat.h"
31652869	32	#include "key.h"
31652869	33	#include "hostfile.h"
a306f2dd	34	#include "auth.h"
7899c98f	35	#include "channels.h"
a306f2dd	36	#include "session.h"
ced49be2	37	#include "uidswap.h"
31652869	38	#ifdef GSSAPI
	39	#include "ssh-gss.h"
	40	#endif
1853d1ef	41	#include "monitor_wrap.h"
9aab0af7	42	#include "buffer.h"
a306f2dd	43
	44	/* import */
	45	extern ServerOptions options;
9aab0af7	46	extern Buffer loginmsg;
94ec8c6b	47
8485ce56	48	static int auth1_process_password(Authctxt , char , size_t);
	49	static int auth1_process_rsa(Authctxt , char , size_t);
	50	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	51	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	52	static int auth1_process_tis_response(Authctxt , char , size_t);
	53
	54	static char client_user = NULL; / Used to fill in remote user for PAM */
	55
	56	struct AuthMethod1 {
	57	int type;
	58	char *name;
	59	int *enabled;
	60	int (method)(Authctxt , char *, size_t);
	61	};
	62
	63	const struct AuthMethod1 auth1_methods[] = {
	64	{
	65	SSH_CMSG_AUTH_PASSWORD, "password",
	66	&options.password_authentication, auth1_process_password
	67	},
	68	{
	69	SSH_CMSG_AUTH_RSA, "rsa",
	70	&options.rsa_authentication, auth1_process_rsa
	71	},
	72	{
	73	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	74	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	75	},
	76	{
	77	SSH_CMSG_AUTH_TIS, "challenge-response",
	78	&options.challenge_response_authentication,
	79	auth1_process_tis_challenge
	80	},
	81	{
	82	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	83	&options.challenge_response_authentication,
	84	auth1_process_tis_response
	85	},
	86	{ -1, NULL, NULL, NULL}
	87	};
	88
	89	static const struct AuthMethod1
	90	*lookup_authmethod1(int type)
	91	{
	92	int i;
	93
c8e9c167	94	for (i = 0; auth1_methods[i].name != NULL; i++)
8485ce56	95	if (auth1_methods[i].type == type)
	96	return (&(auth1_methods[i]));
	97
	98	return (NULL);
	99	}
	100
396c147e	101	static char *
a306f2dd	102	get_authname(int type)
a306f2dd	103	{
8485ce56	104	const struct AuthMethod1 *a;
	105	static char buf[64];
	106
	107	if ((a = lookup_authmethod1(type)) != NULL)
	108	return (a->name);
	109	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	110	return (buf);
	111	}
	112
fe8c3af1	113	/ARGSUSED/
8485ce56	114	static int
	115	auth1_process_password(Authctxt authctxt, char info, size_t infolen)
	116	{
	117	int authenticated = 0;
	118	char *password;
	119	u_int dlen;
	120
	121	/*
	122	* Read user password. It is in plain text, but was
	123	* transmitted over the encrypted channel so it is
	124	* not visible to an outside observer.
	125	*/
	126	password = packet_get_string(&dlen);
	127	packet_check_eom();
	128
	129	/* Try authentication with the password. */
	130	authenticated = PRIVSEP(auth_password(authctxt, password));
	131
	132	memset(password, 0, dlen);
	133	xfree(password);
	134
	135	return (authenticated);
	136	}
	137
fe8c3af1	138	/ARGSUSED/
8485ce56	139	static int
	140	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	141	{
	142	int authenticated = 0;
	143	BIGNUM *n;
	144
	145	/* RSA authentication requested. */
	146	if ((n = BN_new()) == NULL)
	147	fatal("do_authloop: BN_new failed");
	148	packet_get_bignum(n);
	149	packet_check_eom();
	150	authenticated = auth_rsa(authctxt, n);
	151	BN_clear_free(n);
	152
	153	return (authenticated);
	154	}
	155
fe8c3af1	156	/ARGSUSED/
8485ce56	157	static int
	158	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	159	{
a375df46	160	int keybits, authenticated = 0;
8485ce56	161	u_int bits;
	162	Key *client_host_key;
	163	u_int ulen;
	164
	165	/*
	166	* Get client user name. Note that we just have to
	167	* trust the client; root on the client machine can
	168	* claim to be any user.
	169	*/
	170	client_user = packet_get_string(&ulen);
	171
	172	/* Get the client host key. */
	173	client_host_key = key_new(KEY_RSA1);
	174	bits = packet_get_int();
	175	packet_get_bignum(client_host_key->rsa->e);
	176	packet_get_bignum(client_host_key->rsa->n);
	177
a375df46	178	keybits = BN_num_bits(client_host_key->rsa->n);
a375df46	179	if (keybits < 0 \|\| bits != (u_int)keybits) {
8485ce56	180	verbose("Warning: keysize mismatch for client_host_key: "
	181	"actual %d, announced %d",
	182	BN_num_bits(client_host_key->rsa->n), bits);
a306f2dd	183	}
8485ce56	184	packet_check_eom();
	185
	186	authenticated = auth_rhosts_rsa(authctxt, client_user,
	187	client_host_key);
	188	key_free(client_host_key);
	189
	190	snprintf(info, infolen, " ruser %.100s", client_user);
d1cf9a87	191
8485ce56	192	return (authenticated);
	193	}
	194
fe8c3af1	195	/ARGSUSED/
8485ce56	196	static int
	197	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	198	{
	199	char *challenge;
56964485	200
8485ce56	201	if ((challenge = get_challenge(authctxt)) == NULL)
	202	return (0);
	203
	204	debug("sending challenge '%s'", challenge);
	205	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	206	packet_put_cstring(challenge);
	207	xfree(challenge);
	208	packet_send();
	209	packet_write_wait();
	210
	211	return (-1);
	212	}
	213
fe8c3af1	214	/ARGSUSED/
8485ce56	215	static int
	216	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	217	{
	218	int authenticated = 0;
	219	char *response;
	220	u_int dlen;
	221
	222	response = packet_get_string(&dlen);
	223	packet_check_eom();
	224	authenticated = verify_response(authctxt, response);
	225	memset(response, 'r', dlen);
	226	xfree(response);
	227
	228	return (authenticated);
a306f2dd	229	}
	230
	231	/*
59c97189	232	* read packets, try to authenticate the user and
59c97189	233	* return only if authentication is successful
a306f2dd	234	*/
396c147e	235	static void
59c97189	236	do_authloop(Authctxt *authctxt)
a306f2dd	237	{
94ec8c6b	238	int authenticated = 0;
59c97189	239	char info[1024];
8485ce56	240	int prev = 0, type = 0;
8485ce56	241	const struct AuthMethod1 *meth;
59c97189	242
59c97189	243	debug("Attempting authentication for %s%.100s.",
d77347cc	244	authctxt->valid ? "" : "invalid user ", authctxt->user);
59c97189	245
	246	/* If the user has no password, accept authentication immediately. */
	247	if (options.password_authentication &&
1c590258	248	#ifdef KRB5
59c97189	249	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	250	#endif
1853d1ef	251	PRIVSEP(auth_password(authctxt, ""))) {
ece30983	252	#ifdef USE_PAM
	253	if (options.use_pam && (PRIVSEP(do_pam_account())))
	254	#endif
	255	{
	256	auth_log(authctxt, 1, "without authentication", "");
	257	return;
	258	}
59c97189	259	}
a306f2dd	260
	261	/* Indicate that authentication is needed. */
	262	packet_start(SSH_SMSG_FAILURE);
	263	packet_send();
	264	packet_write_wait();
	265
59c97189	266	for (;;) {
94ec8c6b	267	/* default to fail */
	268	authenticated = 0;
	269
59c97189	270	info[0] = '\0';
a306f2dd	271
a306f2dd	272	/* Get a packet from the client. */
05114c74	273	prev = type;
54a5250f	274	type = packet_read();
a306f2dd	275
05114c74	276	/*
	277	* If we started challenge-response authentication but the
	278	* next packet is not a response to our challenge, release
	279	* the resources allocated by get_challenge() (which would
	280	* normally have been released by verify_response() had we
	281	* received such a response)
	282	*/
	283	if (prev == SSH_CMSG_AUTH_TIS &&
	284	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	285	abandon_challenge_response(authctxt);
	286
71709bcd	287	if (authctxt->failures >= options.max_authtries)
71709bcd	288	goto skip;
8485ce56	289	if ((meth = lookup_authmethod1(type)) == NULL) {
	290	logit("Unknown message during authentication: "
	291	"type %d", type);
	292	goto skip;
	293	}
	294
	295	if (!*(meth->enabled)) {
	296	verbose("%s authentication disabled.", meth->name);
	297	goto skip;
a306f2dd	298	}
8485ce56	299
	300	authenticated = meth->method(authctxt, info, sizeof(info));
	301	if (authenticated == -1)
	302	continue; /* "postponed" */
	303
af774732	304	#ifdef BSD_AUTH
	305	if (authctxt->as) {
	306	auth_close(authctxt->as);
	307	authctxt->as = NULL;
	308	}
	309	#endif
59c97189	310	if (!authctxt->valid && authenticated)
	311	fatal("INTERNAL ERROR: authenticated invalid user %s",
	312	authctxt->user);
a306f2dd	313
ef51930f	314	#ifdef _UNICOS
ef51930f	315	if (authenticated && cray_access_denied(authctxt->user)) {
	316	authenticated = 0;
	317	fatal("Access denied for user %s.",authctxt->user);
	318	}
	319	#endif /* _UNICOS */
	320
5077a5f6	321	#ifndef HAVE_CYGWIN
59c97189	322	/* Special handling for root */
5d47f1d4	323	if (authenticated && authctxt->pw->pw_uid == 0 &&
8485ce56	324	!auth_root_allowed(meth->name)) {
8485ce56	325	authenticated = 0;
6039eeef	326	# ifdef SSH_AUDIT_EVENTS
6039eeef	327	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
c00e4d75	328	# endif
c00e4d75	329	}
3c418020	330	#endif
a306f2dd	331
5b9e2464	332	#ifdef USE_PAM
aff51935	333	if (options.use_pam && authenticated &&
9aab0af7	334	!PRIVSEP(do_pam_account())) {
	335	char *msg;
	336	size_t len;
	337
	338	error("Access denied for user %s by PAM account "
98c044d0	339	"configuration", authctxt->user);
9aab0af7	340	len = buffer_len(&loginmsg);
	341	buffer_append(&loginmsg, "\0", 1);
	342	msg = buffer_ptr(&loginmsg);
	343	/* strip trailing newlines */
	344	if (len > 0)
	345	while (len > 0 && msg[--len] == '\n')
	346	msg[len] = '\0';
	347	else
	348	msg = "Access denied.";
b5fc5d94	349	packet_disconnect("%s", msg);
9aab0af7	350	}
5b9e2464	351	#endif
5b9e2464	352
8485ce56	353	skip:
59c97189	354	/* Log before sending the reply */
	355	auth_log(authctxt, authenticated, get_authname(type), info);
	356
a306f2dd	357	if (client_user != NULL) {
	358	xfree(client_user);
	359	client_user = NULL;
	360	}
	361
94ec8c6b	362	if (authenticated)
	363	return;
	364
71709bcd	365	if (++authctxt->failures >= options.max_authtries) {
6039eeef	366	#ifdef SSH_AUDIT_EVENTS
6039eeef	367	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
c00e4d75	368	#endif
59c97189	369	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
c00e4d75	370	}
a306f2dd	371
a306f2dd	372	packet_start(SSH_SMSG_FAILURE);
	373	packet_send();
	374	packet_write_wait();
	375	}
	376	}
	377
	378	/*
	379	* Performs authentication of an incoming connection. Session key has already
	380	* been exchanged and encryption is enabled.
	381	*/
2362db19	382	void
2362db19	383	do_authentication(Authctxt *authctxt)
a306f2dd	384	{
1e3b8b07	385	u_int ulen;
f8d99a32	386	char user, style = NULL;
a306f2dd	387
a306f2dd	388	/* Get the name of the user that we wish to log in as. */
54a5250f	389	packet_read_expect(SSH_CMSG_USER);
a306f2dd	390
	391	/* Get the user name. */
	392	user = packet_get_string(&ulen);
95500969	393	packet_check_eom();
a306f2dd	394
59c97189	395	if ((style = strchr(user, ':')) != NULL)
ced49be2	396	*style++ = '\0';
59c97189	397
59c97189	398	authctxt->user = user;
	399	authctxt->style = style;
	400
a306f2dd	401	/* Verify that the user is a valid user. */
5f1f36b5	402	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
59c97189	403	authctxt->valid = 1;
96d0bf74	404	else {
d77347cc	405	debug("do_authentication: invalid user %s", user);
96d0bf74	406	authctxt->pw = fakepw();
96d0bf74	407	}
a306f2dd	408
bd5c0694	409	setproctitle("%s%s", authctxt->valid ? user : "unknown",
1853d1ef	410	use_privsep ? " [net]" : "");
6172e290	411
a306f2dd	412	#ifdef USE_PAM
7fceb20d	413	if (options.use_pam)
529d73ab	414	PRIVSEP(start_pam(authctxt));
a306f2dd	415	#endif
	416
	417	/*
	418	* If we are not running as root, the user must have the same uid as
8485ce56	419	* the server.
a306f2dd	420	*/
94ec8c6b	421	#ifndef HAVE_CYGWIN
5f1f36b5	422	if (!use_privsep && getuid() != 0 && authctxt->pw &&
5f1f36b5	423	authctxt->pw->pw_uid != getuid())
a306f2dd	424	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	425	#endif
a306f2dd	426
59c97189	427	/*
b4b5d644	428	* Loop until the user has been authenticated or the connection is
	429	* closed, do_authloop() returns only if authentication is successful
	430	*/
59c97189	431	do_authloop(authctxt);
a306f2dd	432
a306f2dd	433	/* The user has been authenticated and accepted. */
94ec8c6b	434	packet_start(SSH_SMSG_SUCCESS);
	435	packet_send();
	436	packet_write_wait();
a306f2dd	437	}