[openssh.git] / 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"

#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
a306f2dd	1	/*
	2	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	3	* All rights reserved
bcbf86ec	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".
a306f2dd	10	*/
	11
	12	#include "includes.h"
94ec8c6b	13
a306f2dd	14	#include "xmalloc.h"
a306f2dd	15	#include "rsa.h"
42f11eb2	16	#include "ssh1.h"
a306f2dd	17	#include "packet.h"
a306f2dd	18	#include "buffer.h"
42f11eb2	19	#include "log.h"
a306f2dd	20	#include "servconf.h"
	21	#include "compat.h"
	22	#include "auth.h"
7899c98f	23	#include "channels.h"
a306f2dd	24	#include "session.h"
ced49be2	25	#include "uidswap.h"
1853d1ef	26	#include "monitor_wrap.h"
9aab0af7	27	#include "buffer.h"
a306f2dd	28
	29	/* import */
	30	extern ServerOptions options;
9aab0af7	31	extern Buffer loginmsg;
94ec8c6b	32
8485ce56	33	static int auth1_process_password(Authctxt , char , size_t);
	34	static int auth1_process_rsa(Authctxt , char , size_t);
	35	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	36	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	37	static int auth1_process_tis_response(Authctxt , char , size_t);
	38
	39	static char client_user = NULL; / Used to fill in remote user for PAM */
	40
	41	struct AuthMethod1 {
	42	int type;
	43	char *name;
	44	int *enabled;
	45	int (method)(Authctxt , char *, size_t);
	46	};
	47
	48	const struct AuthMethod1 auth1_methods[] = {
	49	{
	50	SSH_CMSG_AUTH_PASSWORD, "password",
	51	&options.password_authentication, auth1_process_password
	52	},
	53	{
	54	SSH_CMSG_AUTH_RSA, "rsa",
	55	&options.rsa_authentication, auth1_process_rsa
	56	},
	57	{
	58	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	59	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	60	},
	61	{
	62	SSH_CMSG_AUTH_TIS, "challenge-response",
	63	&options.challenge_response_authentication,
	64	auth1_process_tis_challenge
	65	},
	66	{
	67	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	68	&options.challenge_response_authentication,
	69	auth1_process_tis_response
	70	},
	71	{ -1, NULL, NULL, NULL}
	72	};
	73
	74	static const struct AuthMethod1
	75	*lookup_authmethod1(int type)
	76	{
	77	int i;
	78
c8e9c167	79	for (i = 0; auth1_methods[i].name != NULL; i++)
8485ce56	80	if (auth1_methods[i].type == type)
	81	return (&(auth1_methods[i]));
	82
	83	return (NULL);
	84	}
	85
396c147e	86	static char *
a306f2dd	87	get_authname(int type)
a306f2dd	88	{
8485ce56	89	const struct AuthMethod1 *a;
	90	static char buf[64];
	91
	92	if ((a = lookup_authmethod1(type)) != NULL)
	93	return (a->name);
	94	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	95	return (buf);
	96	}
	97
fe8c3af1	98	/ARGSUSED/
8485ce56	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
fe8c3af1	123	/ARGSUSED/
8485ce56	124	static int
	125	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	126	{
	127	int authenticated = 0;
	128	BIGNUM *n;
	129
	130	/* RSA authentication requested. */
	131	if ((n = BN_new()) == NULL)
	132	fatal("do_authloop: BN_new failed");
	133	packet_get_bignum(n);
	134	packet_check_eom();
	135	authenticated = auth_rsa(authctxt, n);
	136	BN_clear_free(n);
	137
	138	return (authenticated);
	139	}
	140
fe8c3af1	141	/ARGSUSED/
8485ce56	142	static int
	143	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	144	{
a375df46	145	int keybits, authenticated = 0;
8485ce56	146	u_int bits;
	147	Key *client_host_key;
	148	u_int ulen;
	149
	150	/*
	151	* Get client user name. Note that we just have to
	152	* trust the client; root on the client machine can
	153	* claim to be any user.
	154	*/
	155	client_user = packet_get_string(&ulen);
	156
	157	/* Get the client host key. */
	158	client_host_key = key_new(KEY_RSA1);
	159	bits = packet_get_int();
	160	packet_get_bignum(client_host_key->rsa->e);
	161	packet_get_bignum(client_host_key->rsa->n);
	162
a375df46	163	keybits = BN_num_bits(client_host_key->rsa->n);
a375df46	164	if (keybits < 0 \|\| bits != (u_int)keybits) {
8485ce56	165	verbose("Warning: keysize mismatch for client_host_key: "
	166	"actual %d, announced %d",
	167	BN_num_bits(client_host_key->rsa->n), bits);
a306f2dd	168	}
8485ce56	169	packet_check_eom();
	170
	171	authenticated = auth_rhosts_rsa(authctxt, client_user,
	172	client_host_key);
	173	key_free(client_host_key);
	174
	175	snprintf(info, infolen, " ruser %.100s", client_user);
d1cf9a87	176
8485ce56	177	return (authenticated);
	178	}
	179
fe8c3af1	180	/ARGSUSED/
8485ce56	181	static int
	182	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	183	{
	184	char *challenge;
56964485	185
8485ce56	186	if ((challenge = get_challenge(authctxt)) == NULL)
	187	return (0);
	188
	189	debug("sending challenge '%s'", challenge);
	190	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	191	packet_put_cstring(challenge);
	192	xfree(challenge);
	193	packet_send();
	194	packet_write_wait();
	195
	196	return (-1);
	197	}
	198
fe8c3af1	199	/ARGSUSED/
8485ce56	200	static int
	201	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	202	{
	203	int authenticated = 0;
	204	char *response;
	205	u_int dlen;
	206
	207	response = packet_get_string(&dlen);
	208	packet_check_eom();
	209	authenticated = verify_response(authctxt, response);
	210	memset(response, 'r', dlen);
	211	xfree(response);
	212
	213	return (authenticated);
a306f2dd	214	}
	215
	216	/*
59c97189	217	* read packets, try to authenticate the user and
59c97189	218	* return only if authentication is successful
a306f2dd	219	*/
396c147e	220	static void
59c97189	221	do_authloop(Authctxt *authctxt)
a306f2dd	222	{
94ec8c6b	223	int authenticated = 0;
59c97189	224	char info[1024];
8485ce56	225	int prev = 0, type = 0;
8485ce56	226	const struct AuthMethod1 *meth;
59c97189	227
59c97189	228	debug("Attempting authentication for %s%.100s.",
d77347cc	229	authctxt->valid ? "" : "invalid user ", authctxt->user);
59c97189	230
	231	/* If the user has no password, accept authentication immediately. */
	232	if (options.password_authentication &&
1c590258	233	#ifdef KRB5
59c97189	234	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	235	#endif
1853d1ef	236	PRIVSEP(auth_password(authctxt, ""))) {
ece30983	237	#ifdef USE_PAM
	238	if (options.use_pam && (PRIVSEP(do_pam_account())))
	239	#endif
	240	{
	241	auth_log(authctxt, 1, "without authentication", "");
	242	return;
	243	}
59c97189	244	}
a306f2dd	245
	246	/* Indicate that authentication is needed. */
	247	packet_start(SSH_SMSG_FAILURE);
	248	packet_send();
	249	packet_write_wait();
	250
59c97189	251	for (;;) {
94ec8c6b	252	/* default to fail */
	253	authenticated = 0;
	254
59c97189	255	info[0] = '\0';
a306f2dd	256
a306f2dd	257	/* Get a packet from the client. */
05114c74	258	prev = type;
54a5250f	259	type = packet_read();
a306f2dd	260
05114c74	261	/*
	262	* If we started challenge-response authentication but the
	263	* next packet is not a response to our challenge, release
	264	* the resources allocated by get_challenge() (which would
	265	* normally have been released by verify_response() had we
	266	* received such a response)
	267	*/
	268	if (prev == SSH_CMSG_AUTH_TIS &&
	269	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	270	abandon_challenge_response(authctxt);
	271
8485ce56	272	if ((meth = lookup_authmethod1(type)) == NULL) {
	273	logit("Unknown message during authentication: "
	274	"type %d", type);
	275	goto skip;
	276	}
	277
	278	if (!*(meth->enabled)) {
	279	verbose("%s authentication disabled.", meth->name);
	280	goto skip;
a306f2dd	281	}
8485ce56	282
	283	authenticated = meth->method(authctxt, info, sizeof(info));
	284	if (authenticated == -1)
	285	continue; /* "postponed" */
	286
af774732	287	#ifdef BSD_AUTH
	288	if (authctxt->as) {
	289	auth_close(authctxt->as);
	290	authctxt->as = NULL;
	291	}
	292	#endif
59c97189	293	if (!authctxt->valid && authenticated)
	294	fatal("INTERNAL ERROR: authenticated invalid user %s",
	295	authctxt->user);
a306f2dd	296
ef51930f	297	#ifdef _UNICOS
ef51930f	298	if (authenticated && cray_access_denied(authctxt->user)) {
	299	authenticated = 0;
	300	fatal("Access denied for user %s.",authctxt->user);
	301	}
	302	#endif /* _UNICOS */
	303
2b87da3b	304	#ifdef HAVE_CYGWIN
2b87da3b	305	if (authenticated &&
d1cf9a87	306	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
02a57950	307	authctxt->pw)) {
3c62e7eb	308	packet_disconnect("Authentication rejected for uid %d.",
02a57950	309	authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
3c62e7eb	310	authenticated = 0;
3c62e7eb	311	}
3c418020	312	#else
59c97189	313	/* Special handling for root */
5d47f1d4	314	if (authenticated && authctxt->pw->pw_uid == 0 &&
8485ce56	315	!auth_root_allowed(meth->name)) {
8485ce56	316	authenticated = 0;
6039eeef	317	# ifdef SSH_AUDIT_EVENTS
6039eeef	318	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
c00e4d75	319	# endif
c00e4d75	320	}
3c418020	321	#endif
a306f2dd	322
5b9e2464	323	#ifdef USE_PAM
aff51935	324	if (options.use_pam && authenticated &&
9aab0af7	325	!PRIVSEP(do_pam_account())) {
	326	char *msg;
	327	size_t len;
	328
	329	error("Access denied for user %s by PAM account "
98c044d0	330	"configuration", authctxt->user);
9aab0af7	331	len = buffer_len(&loginmsg);
	332	buffer_append(&loginmsg, "\0", 1);
	333	msg = buffer_ptr(&loginmsg);
	334	/* strip trailing newlines */
	335	if (len > 0)
	336	while (len > 0 && msg[--len] == '\n')
	337	msg[len] = '\0';
	338	else
	339	msg = "Access denied.";
	340	packet_disconnect(msg);
	341	}
5b9e2464	342	#endif
5b9e2464	343
8485ce56	344	skip:
59c97189	345	/* Log before sending the reply */
	346	auth_log(authctxt, authenticated, get_authname(type), info);
	347
a306f2dd	348	if (client_user != NULL) {
	349	xfree(client_user);
	350	client_user = NULL;
	351	}
	352
94ec8c6b	353	if (authenticated)
	354	return;
	355
c00e4d75	356	if (authctxt->failures++ > options.max_authtries) {
6039eeef	357	#ifdef SSH_AUDIT_EVENTS
6039eeef	358	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
c00e4d75	359	#endif
59c97189	360	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
c00e4d75	361	}
a306f2dd	362
a306f2dd	363	packet_start(SSH_SMSG_FAILURE);
	364	packet_send();
	365	packet_write_wait();
	366	}
	367	}
	368
	369	/*
	370	* Performs authentication of an incoming connection. Session key has already
	371	* been exchanged and encryption is enabled.
	372	*/
2362db19	373	void
2362db19	374	do_authentication(Authctxt *authctxt)
a306f2dd	375	{
1e3b8b07	376	u_int ulen;
f8d99a32	377	char user, style = NULL;
a306f2dd	378
a306f2dd	379	/* Get the name of the user that we wish to log in as. */
54a5250f	380	packet_read_expect(SSH_CMSG_USER);
a306f2dd	381
	382	/* Get the user name. */
	383	user = packet_get_string(&ulen);
95500969	384	packet_check_eom();
a306f2dd	385
59c97189	386	if ((style = strchr(user, ':')) != NULL)
ced49be2	387	*style++ = '\0';
59c97189	388
59c97189	389	authctxt->user = user;
	390	authctxt->style = style;
	391
a306f2dd	392	/* Verify that the user is a valid user. */
5f1f36b5	393	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
59c97189	394	authctxt->valid = 1;
96d0bf74	395	else {
d77347cc	396	debug("do_authentication: invalid user %s", user);
96d0bf74	397	authctxt->pw = fakepw();
96d0bf74	398	}
a306f2dd	399
bd5c0694	400	setproctitle("%s%s", authctxt->valid ? user : "unknown",
1853d1ef	401	use_privsep ? " [net]" : "");
6172e290	402
a306f2dd	403	#ifdef USE_PAM
7fceb20d	404	if (options.use_pam)
529d73ab	405	PRIVSEP(start_pam(authctxt));
a306f2dd	406	#endif
	407
	408	/*
	409	* If we are not running as root, the user must have the same uid as
8485ce56	410	* the server.
a306f2dd	411	*/
94ec8c6b	412	#ifndef HAVE_CYGWIN
5f1f36b5	413	if (!use_privsep && getuid() != 0 && authctxt->pw &&
5f1f36b5	414	authctxt->pw->pw_uid != getuid())
a306f2dd	415	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	416	#endif
a306f2dd	417
59c97189	418	/*
b4b5d644	419	* Loop until the user has been authenticated or the connection is
	420	* closed, do_authloop() returns only if authentication is successful
	421	*/
59c97189	422	do_authloop(authctxt);
a306f2dd	423
a306f2dd	424	/* The user has been authenticated and accepted. */
94ec8c6b	425	packet_start(SSH_SMSG_SUCCESS);
	426	packet_send();
	427	packet_write_wait();
a306f2dd	428	}