[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);
}

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