[openssh.git] / auth1.c

/* $OpenBSD: auth1.c,v 1.68 2006/07/22 20:48:22 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 <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
00146caa	1	/* $OpenBSD: auth1.c,v 1.68 2006/07/22 20:48:22 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
00146caa	17	#include <string.h>
67514848	18	#include <unistd.h>
67514848	19
a306f2dd	20	#include "xmalloc.h"
a306f2dd	21	#include "rsa.h"
42f11eb2	22	#include "ssh1.h"
a306f2dd	23	#include "packet.h"
a306f2dd	24	#include "buffer.h"
42f11eb2	25	#include "log.h"
a306f2dd	26	#include "servconf.h"
	27	#include "compat.h"
	28	#include "auth.h"
7899c98f	29	#include "channels.h"
a306f2dd	30	#include "session.h"
ced49be2	31	#include "uidswap.h"
1853d1ef	32	#include "monitor_wrap.h"
9aab0af7	33	#include "buffer.h"
a306f2dd	34
	35	/* import */
	36	extern ServerOptions options;
9aab0af7	37	extern Buffer loginmsg;
94ec8c6b	38
8485ce56	39	static int auth1_process_password(Authctxt , char , size_t);
	40	static int auth1_process_rsa(Authctxt , char , size_t);
	41	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	42	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	43	static int auth1_process_tis_response(Authctxt , char , size_t);
	44
	45	static char client_user = NULL; / Used to fill in remote user for PAM */
	46
	47	struct AuthMethod1 {
	48	int type;
	49	char *name;
	50	int *enabled;
	51	int (method)(Authctxt , char *, size_t);
	52	};
	53
	54	const struct AuthMethod1 auth1_methods[] = {
	55	{
	56	SSH_CMSG_AUTH_PASSWORD, "password",
	57	&options.password_authentication, auth1_process_password
	58	},
	59	{
	60	SSH_CMSG_AUTH_RSA, "rsa",
	61	&options.rsa_authentication, auth1_process_rsa
	62	},
	63	{
	64	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	65	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	66	},
	67	{
	68	SSH_CMSG_AUTH_TIS, "challenge-response",
	69	&options.challenge_response_authentication,
	70	auth1_process_tis_challenge
	71	},
	72	{
	73	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	74	&options.challenge_response_authentication,
	75	auth1_process_tis_response
	76	},
	77	{ -1, NULL, NULL, NULL}
	78	};
	79
	80	static const struct AuthMethod1
	81	*lookup_authmethod1(int type)
	82	{
	83	int i;
	84
c8e9c167	85	for (i = 0; auth1_methods[i].name != NULL; i++)
8485ce56	86	if (auth1_methods[i].type == type)
	87	return (&(auth1_methods[i]));
	88
	89	return (NULL);
	90	}
	91
396c147e	92	static char *
a306f2dd	93	get_authname(int type)
a306f2dd	94	{
8485ce56	95	const struct AuthMethod1 *a;
	96	static char buf[64];
	97
	98	if ((a = lookup_authmethod1(type)) != NULL)
	99	return (a->name);
	100	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	101	return (buf);
	102	}
	103
fe8c3af1	104	/ARGSUSED/
8485ce56	105	static int
	106	auth1_process_password(Authctxt authctxt, char info, size_t infolen)
	107	{
	108	int authenticated = 0;
	109	char *password;
	110	u_int dlen;
	111
	112	/*
	113	* Read user password. It is in plain text, but was
	114	* transmitted over the encrypted channel so it is
	115	* not visible to an outside observer.
	116	*/
	117	password = packet_get_string(&dlen);
	118	packet_check_eom();
	119
	120	/* Try authentication with the password. */
	121	authenticated = PRIVSEP(auth_password(authctxt, password));
	122
	123	memset(password, 0, dlen);
	124	xfree(password);
	125
	126	return (authenticated);
	127	}
	128
fe8c3af1	129	/ARGSUSED/
8485ce56	130	static int
	131	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	132	{
	133	int authenticated = 0;
	134	BIGNUM *n;
	135
	136	/* RSA authentication requested. */
	137	if ((n = BN_new()) == NULL)
	138	fatal("do_authloop: BN_new failed");
	139	packet_get_bignum(n);
	140	packet_check_eom();
	141	authenticated = auth_rsa(authctxt, n);
	142	BN_clear_free(n);
	143
	144	return (authenticated);
	145	}
	146
fe8c3af1	147	/ARGSUSED/
8485ce56	148	static int
	149	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	150	{
a375df46	151	int keybits, authenticated = 0;
8485ce56	152	u_int bits;
	153	Key *client_host_key;
	154	u_int ulen;
	155
	156	/*
	157	* Get client user name. Note that we just have to
	158	* trust the client; root on the client machine can
	159	* claim to be any user.
	160	*/
	161	client_user = packet_get_string(&ulen);
	162
	163	/* Get the client host key. */
	164	client_host_key = key_new(KEY_RSA1);
	165	bits = packet_get_int();
	166	packet_get_bignum(client_host_key->rsa->e);
	167	packet_get_bignum(client_host_key->rsa->n);
	168
a375df46	169	keybits = BN_num_bits(client_host_key->rsa->n);
a375df46	170	if (keybits < 0 \|\| bits != (u_int)keybits) {
8485ce56	171	verbose("Warning: keysize mismatch for client_host_key: "
	172	"actual %d, announced %d",
	173	BN_num_bits(client_host_key->rsa->n), bits);
a306f2dd	174	}
8485ce56	175	packet_check_eom();
	176
	177	authenticated = auth_rhosts_rsa(authctxt, client_user,
	178	client_host_key);
	179	key_free(client_host_key);
	180
	181	snprintf(info, infolen, " ruser %.100s", client_user);
d1cf9a87	182
8485ce56	183	return (authenticated);
	184	}
	185
fe8c3af1	186	/ARGSUSED/
8485ce56	187	static int
	188	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	189	{
	190	char *challenge;
56964485	191
8485ce56	192	if ((challenge = get_challenge(authctxt)) == NULL)
	193	return (0);
	194
	195	debug("sending challenge '%s'", challenge);
	196	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	197	packet_put_cstring(challenge);
	198	xfree(challenge);
	199	packet_send();
	200	packet_write_wait();
	201
	202	return (-1);
	203	}
	204
fe8c3af1	205	/ARGSUSED/
8485ce56	206	static int
	207	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	208	{
	209	int authenticated = 0;
	210	char *response;
	211	u_int dlen;
	212
	213	response = packet_get_string(&dlen);
	214	packet_check_eom();
	215	authenticated = verify_response(authctxt, response);
	216	memset(response, 'r', dlen);
	217	xfree(response);
	218
	219	return (authenticated);
a306f2dd	220	}
	221
	222	/*
59c97189	223	* read packets, try to authenticate the user and
59c97189	224	* return only if authentication is successful
a306f2dd	225	*/
396c147e	226	static void
59c97189	227	do_authloop(Authctxt *authctxt)
a306f2dd	228	{
94ec8c6b	229	int authenticated = 0;
59c97189	230	char info[1024];
8485ce56	231	int prev = 0, type = 0;
8485ce56	232	const struct AuthMethod1 *meth;
59c97189	233
59c97189	234	debug("Attempting authentication for %s%.100s.",
d77347cc	235	authctxt->valid ? "" : "invalid user ", authctxt->user);
59c97189	236
	237	/* If the user has no password, accept authentication immediately. */
	238	if (options.password_authentication &&
1c590258	239	#ifdef KRB5
59c97189	240	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	241	#endif
1853d1ef	242	PRIVSEP(auth_password(authctxt, ""))) {
ece30983	243	#ifdef USE_PAM
	244	if (options.use_pam && (PRIVSEP(do_pam_account())))
	245	#endif
	246	{
	247	auth_log(authctxt, 1, "without authentication", "");
	248	return;
	249	}
59c97189	250	}
a306f2dd	251
	252	/* Indicate that authentication is needed. */
	253	packet_start(SSH_SMSG_FAILURE);
	254	packet_send();
	255	packet_write_wait();
	256
59c97189	257	for (;;) {
94ec8c6b	258	/* default to fail */
	259	authenticated = 0;
	260
59c97189	261	info[0] = '\0';
a306f2dd	262
a306f2dd	263	/* Get a packet from the client. */
05114c74	264	prev = type;
54a5250f	265	type = packet_read();
a306f2dd	266
05114c74	267	/*
	268	* If we started challenge-response authentication but the
	269	* next packet is not a response to our challenge, release
	270	* the resources allocated by get_challenge() (which would
	271	* normally have been released by verify_response() had we
	272	* received such a response)
	273	*/
	274	if (prev == SSH_CMSG_AUTH_TIS &&
	275	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	276	abandon_challenge_response(authctxt);
	277
8485ce56	278	if ((meth = lookup_authmethod1(type)) == NULL) {
	279	logit("Unknown message during authentication: "
	280	"type %d", type);
	281	goto skip;
	282	}
	283
	284	if (!*(meth->enabled)) {
	285	verbose("%s authentication disabled.", meth->name);
	286	goto skip;
a306f2dd	287	}
8485ce56	288
	289	authenticated = meth->method(authctxt, info, sizeof(info));
	290	if (authenticated == -1)
	291	continue; /* "postponed" */
	292
af774732	293	#ifdef BSD_AUTH
	294	if (authctxt->as) {
	295	auth_close(authctxt->as);
	296	authctxt->as = NULL;
	297	}
	298	#endif
59c97189	299	if (!authctxt->valid && authenticated)
	300	fatal("INTERNAL ERROR: authenticated invalid user %s",
	301	authctxt->user);
a306f2dd	302
ef51930f	303	#ifdef _UNICOS
ef51930f	304	if (authenticated && cray_access_denied(authctxt->user)) {
	305	authenticated = 0;
	306	fatal("Access denied for user %s.",authctxt->user);
	307	}
	308	#endif /* _UNICOS */
	309
2b87da3b	310	#ifdef HAVE_CYGWIN
2b87da3b	311	if (authenticated &&
d1cf9a87	312	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
02a57950	313	authctxt->pw)) {
3c62e7eb	314	packet_disconnect("Authentication rejected for uid %d.",
02a57950	315	authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
3c62e7eb	316	authenticated = 0;
3c62e7eb	317	}
3c418020	318	#else
59c97189	319	/* Special handling for root */
5d47f1d4	320	if (authenticated && authctxt->pw->pw_uid == 0 &&
8485ce56	321	!auth_root_allowed(meth->name)) {
8485ce56	322	authenticated = 0;
6039eeef	323	# ifdef SSH_AUDIT_EVENTS
6039eeef	324	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
c00e4d75	325	# endif
c00e4d75	326	}
3c418020	327	#endif
a306f2dd	328
5b9e2464	329	#ifdef USE_PAM
aff51935	330	if (options.use_pam && authenticated &&
9aab0af7	331	!PRIVSEP(do_pam_account())) {
	332	char *msg;
	333	size_t len;
	334
	335	error("Access denied for user %s by PAM account "
98c044d0	336	"configuration", authctxt->user);
9aab0af7	337	len = buffer_len(&loginmsg);
	338	buffer_append(&loginmsg, "\0", 1);
	339	msg = buffer_ptr(&loginmsg);
	340	/* strip trailing newlines */
	341	if (len > 0)
	342	while (len > 0 && msg[--len] == '\n')
	343	msg[len] = '\0';
	344	else
	345	msg = "Access denied.";
	346	packet_disconnect(msg);
	347	}
5b9e2464	348	#endif
5b9e2464	349
8485ce56	350	skip:
59c97189	351	/* Log before sending the reply */
	352	auth_log(authctxt, authenticated, get_authname(type), info);
	353
a306f2dd	354	if (client_user != NULL) {
	355	xfree(client_user);
	356	client_user = NULL;
	357	}
	358
94ec8c6b	359	if (authenticated)
	360	return;
	361
c00e4d75	362	if (authctxt->failures++ > options.max_authtries) {
6039eeef	363	#ifdef SSH_AUDIT_EVENTS
6039eeef	364	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
c00e4d75	365	#endif
59c97189	366	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
c00e4d75	367	}
a306f2dd	368
a306f2dd	369	packet_start(SSH_SMSG_FAILURE);
	370	packet_send();
	371	packet_write_wait();
	372	}
	373	}
	374
	375	/*
	376	* Performs authentication of an incoming connection. Session key has already
	377	* been exchanged and encryption is enabled.
	378	*/
2362db19	379	void
2362db19	380	do_authentication(Authctxt *authctxt)
a306f2dd	381	{
1e3b8b07	382	u_int ulen;
f8d99a32	383	char user, style = NULL;
a306f2dd	384
a306f2dd	385	/* Get the name of the user that we wish to log in as. */
54a5250f	386	packet_read_expect(SSH_CMSG_USER);
a306f2dd	387
	388	/* Get the user name. */
	389	user = packet_get_string(&ulen);
95500969	390	packet_check_eom();
a306f2dd	391
59c97189	392	if ((style = strchr(user, ':')) != NULL)
ced49be2	393	*style++ = '\0';
59c97189	394
59c97189	395	authctxt->user = user;
	396	authctxt->style = style;
	397
a306f2dd	398	/* Verify that the user is a valid user. */
5f1f36b5	399	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
59c97189	400	authctxt->valid = 1;
96d0bf74	401	else {
d77347cc	402	debug("do_authentication: invalid user %s", user);
96d0bf74	403	authctxt->pw = fakepw();
96d0bf74	404	}
a306f2dd	405
bd5c0694	406	setproctitle("%s%s", authctxt->valid ? user : "unknown",
1853d1ef	407	use_privsep ? " [net]" : "");
6172e290	408
a306f2dd	409	#ifdef USE_PAM
7fceb20d	410	if (options.use_pam)
529d73ab	411	PRIVSEP(start_pam(authctxt));
a306f2dd	412	#endif
	413
	414	/*
	415	* If we are not running as root, the user must have the same uid as
8485ce56	416	* the server.
a306f2dd	417	*/
94ec8c6b	418	#ifndef HAVE_CYGWIN
5f1f36b5	419	if (!use_privsep && getuid() != 0 && authctxt->pw &&
5f1f36b5	420	authctxt->pw->pw_uid != getuid())
a306f2dd	421	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	422	#endif
a306f2dd	423
59c97189	424	/*
b4b5d644	425	* Loop until the user has been authenticated or the connection is
	426	* closed, do_authloop() returns only if authentication is successful
	427	*/
59c97189	428	do_authloop(authctxt);
a306f2dd	429
a306f2dd	430	/* The user has been authenticated and accepted. */
94ec8c6b	431	packet_start(SSH_SMSG_SUCCESS);
	432	packet_send();
	433	packet_write_wait();
a306f2dd	434	}