[openssh.git] / auth1.c

/* $OpenBSD: auth1.c,v 1.69 2006/08/01 23:22:47 stevesk 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 <stdio.h>
#include <string.h>
#include <unistd.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 "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);
}

/*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 ((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
cf851879	1	/* $OpenBSD: auth1.c,v 1.69 2006/08/01 23:22:47 stevesk 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
cf851879	17	#include <stdio.h>
00146caa	18	#include <string.h>
67514848	19	#include <unistd.h>
67514848	20
a306f2dd	21	#include "xmalloc.h"
a306f2dd	22	#include "rsa.h"
42f11eb2	23	#include "ssh1.h"
a306f2dd	24	#include "packet.h"
a306f2dd	25	#include "buffer.h"
42f11eb2	26	#include "log.h"
a306f2dd	27	#include "servconf.h"
	28	#include "compat.h"
	29	#include "auth.h"
7899c98f	30	#include "channels.h"
a306f2dd	31	#include "session.h"
ced49be2	32	#include "uidswap.h"
1853d1ef	33	#include "monitor_wrap.h"
9aab0af7	34	#include "buffer.h"
a306f2dd	35
	36	/* import */
	37	extern ServerOptions options;
9aab0af7	38	extern Buffer loginmsg;
94ec8c6b	39
8485ce56	40	static int auth1_process_password(Authctxt , char , size_t);
	41	static int auth1_process_rsa(Authctxt , char , size_t);
	42	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	43	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	44	static int auth1_process_tis_response(Authctxt , char , size_t);
	45
	46	static char client_user = NULL; / Used to fill in remote user for PAM */
	47
	48	struct AuthMethod1 {
	49	int type;
	50	char *name;
	51	int *enabled;
	52	int (method)(Authctxt , char *, size_t);
	53	};
	54
	55	const struct AuthMethod1 auth1_methods[] = {
	56	{
	57	SSH_CMSG_AUTH_PASSWORD, "password",
	58	&options.password_authentication, auth1_process_password
	59	},
	60	{
	61	SSH_CMSG_AUTH_RSA, "rsa",
	62	&options.rsa_authentication, auth1_process_rsa
	63	},
	64	{
	65	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	66	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	67	},
	68	{
	69	SSH_CMSG_AUTH_TIS, "challenge-response",
	70	&options.challenge_response_authentication,
	71	auth1_process_tis_challenge
	72	},
	73	{
	74	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	75	&options.challenge_response_authentication,
	76	auth1_process_tis_response
	77	},
	78	{ -1, NULL, NULL, NULL}
	79	};
	80
	81	static const struct AuthMethod1
	82	*lookup_authmethod1(int type)
	83	{
	84	int i;
	85
c8e9c167	86	for (i = 0; auth1_methods[i].name != NULL; i++)
8485ce56	87	if (auth1_methods[i].type == type)
	88	return (&(auth1_methods[i]));
	89
	90	return (NULL);
	91	}
	92
396c147e	93	static char *
a306f2dd	94	get_authname(int type)
a306f2dd	95	{
8485ce56	96	const struct AuthMethod1 *a;
	97	static char buf[64];
	98
	99	if ((a = lookup_authmethod1(type)) != NULL)
	100	return (a->name);
	101	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	102	return (buf);
	103	}
	104
fe8c3af1	105	/ARGSUSED/
8485ce56	106	static int
	107	auth1_process_password(Authctxt authctxt, char info, size_t infolen)
	108	{
	109	int authenticated = 0;
	110	char *password;
	111	u_int dlen;
	112
	113	/*
	114	* Read user password. It is in plain text, but was
	115	* transmitted over the encrypted channel so it is
	116	* not visible to an outside observer.
	117	*/
	118	password = packet_get_string(&dlen);
	119	packet_check_eom();
	120
	121	/* Try authentication with the password. */
	122	authenticated = PRIVSEP(auth_password(authctxt, password));
	123
	124	memset(password, 0, dlen);
	125	xfree(password);
	126
	127	return (authenticated);
	128	}
	129
fe8c3af1	130	/ARGSUSED/
8485ce56	131	static int
	132	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	133	{
	134	int authenticated = 0;
	135	BIGNUM *n;
	136
	137	/* RSA authentication requested. */
	138	if ((n = BN_new()) == NULL)
	139	fatal("do_authloop: BN_new failed");
	140	packet_get_bignum(n);
	141	packet_check_eom();
	142	authenticated = auth_rsa(authctxt, n);
	143	BN_clear_free(n);
	144
	145	return (authenticated);
	146	}
	147
fe8c3af1	148	/ARGSUSED/
8485ce56	149	static int
	150	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	151	{
a375df46	152	int keybits, authenticated = 0;
8485ce56	153	u_int bits;
	154	Key *client_host_key;
	155	u_int ulen;
	156
	157	/*
	158	* Get client user name. Note that we just have to
	159	* trust the client; root on the client machine can
	160	* claim to be any user.
	161	*/
	162	client_user = packet_get_string(&ulen);
	163
	164	/* Get the client host key. */
	165	client_host_key = key_new(KEY_RSA1);
	166	bits = packet_get_int();
	167	packet_get_bignum(client_host_key->rsa->e);
	168	packet_get_bignum(client_host_key->rsa->n);
	169
a375df46	170	keybits = BN_num_bits(client_host_key->rsa->n);
a375df46	171	if (keybits < 0 \|\| bits != (u_int)keybits) {
8485ce56	172	verbose("Warning: keysize mismatch for client_host_key: "
	173	"actual %d, announced %d",
	174	BN_num_bits(client_host_key->rsa->n), bits);
a306f2dd	175	}
8485ce56	176	packet_check_eom();
	177
	178	authenticated = auth_rhosts_rsa(authctxt, client_user,
	179	client_host_key);
	180	key_free(client_host_key);
	181
	182	snprintf(info, infolen, " ruser %.100s", client_user);
d1cf9a87	183
8485ce56	184	return (authenticated);
	185	}
	186
fe8c3af1	187	/ARGSUSED/
8485ce56	188	static int
	189	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	190	{
	191	char *challenge;
56964485	192
8485ce56	193	if ((challenge = get_challenge(authctxt)) == NULL)
	194	return (0);
	195
	196	debug("sending challenge '%s'", challenge);
	197	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	198	packet_put_cstring(challenge);
	199	xfree(challenge);
	200	packet_send();
	201	packet_write_wait();
	202
	203	return (-1);
	204	}
	205
fe8c3af1	206	/ARGSUSED/
8485ce56	207	static int
	208	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	209	{
	210	int authenticated = 0;
	211	char *response;
	212	u_int dlen;
	213
	214	response = packet_get_string(&dlen);
	215	packet_check_eom();
	216	authenticated = verify_response(authctxt, response);
	217	memset(response, 'r', dlen);
	218	xfree(response);
	219
	220	return (authenticated);
a306f2dd	221	}
	222
	223	/*
59c97189	224	* read packets, try to authenticate the user and
59c97189	225	* return only if authentication is successful
a306f2dd	226	*/
396c147e	227	static void
59c97189	228	do_authloop(Authctxt *authctxt)
a306f2dd	229	{
94ec8c6b	230	int authenticated = 0;
59c97189	231	char info[1024];
8485ce56	232	int prev = 0, type = 0;
8485ce56	233	const struct AuthMethod1 *meth;
59c97189	234
59c97189	235	debug("Attempting authentication for %s%.100s.",
d77347cc	236	authctxt->valid ? "" : "invalid user ", authctxt->user);
59c97189	237
	238	/* If the user has no password, accept authentication immediately. */
	239	if (options.password_authentication &&
1c590258	240	#ifdef KRB5
59c97189	241	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	242	#endif
1853d1ef	243	PRIVSEP(auth_password(authctxt, ""))) {
ece30983	244	#ifdef USE_PAM
	245	if (options.use_pam && (PRIVSEP(do_pam_account())))
	246	#endif
	247	{
	248	auth_log(authctxt, 1, "without authentication", "");
	249	return;
	250	}
59c97189	251	}
a306f2dd	252
	253	/* Indicate that authentication is needed. */
	254	packet_start(SSH_SMSG_FAILURE);
	255	packet_send();
	256	packet_write_wait();
	257
59c97189	258	for (;;) {
94ec8c6b	259	/* default to fail */
	260	authenticated = 0;
	261
59c97189	262	info[0] = '\0';
a306f2dd	263
a306f2dd	264	/* Get a packet from the client. */
05114c74	265	prev = type;
54a5250f	266	type = packet_read();
a306f2dd	267
05114c74	268	/*
	269	* If we started challenge-response authentication but the
	270	* next packet is not a response to our challenge, release
	271	* the resources allocated by get_challenge() (which would
	272	* normally have been released by verify_response() had we
	273	* received such a response)
	274	*/
	275	if (prev == SSH_CMSG_AUTH_TIS &&
	276	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	277	abandon_challenge_response(authctxt);
	278
8485ce56	279	if ((meth = lookup_authmethod1(type)) == NULL) {
	280	logit("Unknown message during authentication: "
	281	"type %d", type);
	282	goto skip;
	283	}
	284
	285	if (!*(meth->enabled)) {
	286	verbose("%s authentication disabled.", meth->name);
	287	goto skip;
a306f2dd	288	}
8485ce56	289
	290	authenticated = meth->method(authctxt, info, sizeof(info));
	291	if (authenticated == -1)
	292	continue; /* "postponed" */
	293
af774732	294	#ifdef BSD_AUTH
	295	if (authctxt->as) {
	296	auth_close(authctxt->as);
	297	authctxt->as = NULL;
	298	}
	299	#endif
59c97189	300	if (!authctxt->valid && authenticated)
	301	fatal("INTERNAL ERROR: authenticated invalid user %s",
	302	authctxt->user);
a306f2dd	303
ef51930f	304	#ifdef _UNICOS
ef51930f	305	if (authenticated && cray_access_denied(authctxt->user)) {
	306	authenticated = 0;
	307	fatal("Access denied for user %s.",authctxt->user);
	308	}
	309	#endif /* _UNICOS */
	310
2b87da3b	311	#ifdef HAVE_CYGWIN
2b87da3b	312	if (authenticated &&
d1cf9a87	313	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
02a57950	314	authctxt->pw)) {
3c62e7eb	315	packet_disconnect("Authentication rejected for uid %d.",
02a57950	316	authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
3c62e7eb	317	authenticated = 0;
3c62e7eb	318	}
3c418020	319	#else
59c97189	320	/* Special handling for root */
5d47f1d4	321	if (authenticated && authctxt->pw->pw_uid == 0 &&
8485ce56	322	!auth_root_allowed(meth->name)) {
8485ce56	323	authenticated = 0;
6039eeef	324	# ifdef SSH_AUDIT_EVENTS
6039eeef	325	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
c00e4d75	326	# endif
c00e4d75	327	}
3c418020	328	#endif
a306f2dd	329
5b9e2464	330	#ifdef USE_PAM
aff51935	331	if (options.use_pam && authenticated &&
9aab0af7	332	!PRIVSEP(do_pam_account())) {
	333	char *msg;
	334	size_t len;
	335
	336	error("Access denied for user %s by PAM account "
98c044d0	337	"configuration", authctxt->user);
9aab0af7	338	len = buffer_len(&loginmsg);
	339	buffer_append(&loginmsg, "\0", 1);
	340	msg = buffer_ptr(&loginmsg);
	341	/* strip trailing newlines */
	342	if (len > 0)
	343	while (len > 0 && msg[--len] == '\n')
	344	msg[len] = '\0';
	345	else
	346	msg = "Access denied.";
	347	packet_disconnect(msg);
	348	}
5b9e2464	349	#endif
5b9e2464	350
8485ce56	351	skip:
59c97189	352	/* Log before sending the reply */
	353	auth_log(authctxt, authenticated, get_authname(type), info);
	354
a306f2dd	355	if (client_user != NULL) {
	356	xfree(client_user);
	357	client_user = NULL;
	358	}
	359
94ec8c6b	360	if (authenticated)
	361	return;
	362
c00e4d75	363	if (authctxt->failures++ > options.max_authtries) {
6039eeef	364	#ifdef SSH_AUDIT_EVENTS
6039eeef	365	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
c00e4d75	366	#endif
59c97189	367	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
c00e4d75	368	}
a306f2dd	369
a306f2dd	370	packet_start(SSH_SMSG_FAILURE);
	371	packet_send();
	372	packet_write_wait();
	373	}
	374	}
	375
	376	/*
	377	* Performs authentication of an incoming connection. Session key has already
	378	* been exchanged and encryption is enabled.
	379	*/
2362db19	380	void
2362db19	381	do_authentication(Authctxt *authctxt)
a306f2dd	382	{
1e3b8b07	383	u_int ulen;
f8d99a32	384	char user, style = NULL;
a306f2dd	385
a306f2dd	386	/* Get the name of the user that we wish to log in as. */
54a5250f	387	packet_read_expect(SSH_CMSG_USER);
a306f2dd	388
	389	/* Get the user name. */
	390	user = packet_get_string(&ulen);
95500969	391	packet_check_eom();
a306f2dd	392
59c97189	393	if ((style = strchr(user, ':')) != NULL)
ced49be2	394	*style++ = '\0';
59c97189	395
59c97189	396	authctxt->user = user;
	397	authctxt->style = style;
	398
a306f2dd	399	/* Verify that the user is a valid user. */
5f1f36b5	400	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
59c97189	401	authctxt->valid = 1;
96d0bf74	402	else {
d77347cc	403	debug("do_authentication: invalid user %s", user);
96d0bf74	404	authctxt->pw = fakepw();
96d0bf74	405	}
a306f2dd	406
bd5c0694	407	setproctitle("%s%s", authctxt->valid ? user : "unknown",
1853d1ef	408	use_privsep ? " [net]" : "");
6172e290	409
a306f2dd	410	#ifdef USE_PAM
7fceb20d	411	if (options.use_pam)
529d73ab	412	PRIVSEP(start_pam(authctxt));
a306f2dd	413	#endif
	414
	415	/*
	416	* If we are not running as root, the user must have the same uid as
8485ce56	417	* the server.
a306f2dd	418	*/
94ec8c6b	419	#ifndef HAVE_CYGWIN
5f1f36b5	420	if (!use_privsep && getuid() != 0 && authctxt->pw &&
5f1f36b5	421	authctxt->pw->pw_uid != getuid())
a306f2dd	422	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	423	#endif
a306f2dd	424
59c97189	425	/*
b4b5d644	426	* Loop until the user has been authenticated or the connection is
	427	* closed, do_authloop() returns only if authentication is successful
	428	*/
59c97189	429	do_authloop(authctxt);
a306f2dd	430
a306f2dd	431	/* The user has been authenticated and accepted. */
94ec8c6b	432	packet_start(SSH_SMSG_SUCCESS);
	433	packet_send();
	434	packet_write_wait();
a306f2dd	435	}