[gssapi-openssh.git] / openssh / auth1.c

/* $OpenBSD: auth1.c,v 1.71 2007/09/21 08:15:29 djm Exp $ */
/*
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"

#include <sys/types.h>

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

#include "xmalloc.h"
#include "rsa.h"
#include "ssh1.h"
#include "packet.h"
#include "buffer.h"
#include "log.h"
#include "servconf.h"
#include "compat.h"
#include "key.h"
#include "hostfile.h"
#include "auth.h"
#include "channels.h"
#include "session.h"
#include "uidswap.h"
#ifdef GSSAPI
#include "ssh-gss.h"
#endif
#include "monitor_wrap.h"
#include "buffer.h"

/* import */
extern ServerOptions options;
extern Buffer loginmsg;

static int auth1_process_password(Authctxt *, char *, size_t);
static int auth1_process_rsa(Authctxt *, char *, size_t);
static int auth1_process_rhosts_rsa(Authctxt *, char *, size_t);
static int auth1_process_tis_challenge(Authctxt *, char *, size_t);
static int auth1_process_tis_response(Authctxt *, char *, size_t);

static char *client_user = NULL;    /* Used to fill in remote user for PAM */

struct AuthMethod1 {
	int type;
	char *name;
	int *enabled;
	int (*method)(Authctxt *, char *, size_t);
};

const struct AuthMethod1 auth1_methods[] = {
	{
		SSH_CMSG_AUTH_PASSWORD, "password",
		&options.password_authentication, auth1_process_password
	},
	{
		SSH_CMSG_AUTH_RSA, "rsa",
		&options.rsa_authentication, auth1_process_rsa
	},
	{
		SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
		&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	},
	{
		SSH_CMSG_AUTH_TIS, "challenge-response",
		&options.challenge_response_authentication,
		auth1_process_tis_challenge
	},
	{
		SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
		&options.challenge_response_authentication,
		auth1_process_tis_response
	},
	{ -1, NULL, NULL, NULL}
};

static const struct AuthMethod1
*lookup_authmethod1(int type)
{
	int i;

	for (i = 0; auth1_methods[i].name != NULL; i++)
		if (auth1_methods[i].type == type)
			return (&(auth1_methods[i]));

	return (NULL);
}

static char *
get_authname(int type)
{
	const struct AuthMethod1 *a;
	static char buf[64];

	if ((a = lookup_authmethod1(type)) != NULL)
		return (a->name);
	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	return (buf);
}

/*ARGSUSED*/
static int
auth1_process_password(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	char *password;
	u_int dlen;

	/*
	 * Read user password.  It is in plain text, but was
	 * transmitted over the encrypted channel so it is
	 * not visible to an outside observer.
	 */
	password = packet_get_string(&dlen);
	packet_check_eom();

	/* Try authentication with the password. */
	authenticated = PRIVSEP(auth_password(authctxt, password));

	memset(password, 0, dlen);
	xfree(password);

	return (authenticated);
}

/*ARGSUSED*/
static int
auth1_process_rsa(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	BIGNUM *n;

	/* RSA authentication requested. */
	if ((n = BN_new()) == NULL)
		fatal("do_authloop: BN_new failed");
	packet_get_bignum(n);
	packet_check_eom();
	authenticated = auth_rsa(authctxt, n);
	BN_clear_free(n);

	return (authenticated);
}

/*ARGSUSED*/
static int
auth1_process_rhosts_rsa(Authctxt *authctxt, char *info, size_t infolen)
{
	int keybits, authenticated = 0;
	u_int bits;
	Key *client_host_key;
	u_int ulen;

	/*
	 * Get client user name.  Note that we just have to
	 * trust the client; root on the client machine can
	 * claim to be any user.
	 */
	client_user = packet_get_string(&ulen);

	/* Get the client host key. */
	client_host_key = key_new(KEY_RSA1);
	bits = packet_get_int();
	packet_get_bignum(client_host_key->rsa->e);
	packet_get_bignum(client_host_key->rsa->n);

	keybits = BN_num_bits(client_host_key->rsa->n);
	if (keybits < 0 || bits != (u_int)keybits) {
		verbose("Warning: keysize mismatch for client_host_key: "
		    "actual %d, announced %d",
		    BN_num_bits(client_host_key->rsa->n), bits);
	}
	packet_check_eom();

	authenticated = auth_rhosts_rsa(authctxt, client_user,
	    client_host_key);
	key_free(client_host_key);

	snprintf(info, infolen, " ruser %.100s", client_user);

	return (authenticated);
}

/*ARGSUSED*/
static int
auth1_process_tis_challenge(Authctxt *authctxt, char *info, size_t infolen)
{
	char *challenge;

	if ((challenge = get_challenge(authctxt)) == NULL)
		return (0);

	debug("sending challenge '%s'", challenge);
	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	packet_put_cstring(challenge);
	xfree(challenge);
	packet_send();
	packet_write_wait();

	return (-1);
}

/*ARGSUSED*/
static int
auth1_process_tis_response(Authctxt *authctxt, char *info, size_t infolen)
{
	int authenticated = 0;
	char *response;
	u_int dlen;

	response = packet_get_string(&dlen);
	packet_check_eom();
	authenticated = verify_response(authctxt, response);
	memset(response, 'r', dlen);
	xfree(response);

	return (authenticated);
}

/*
 * read packets, try to authenticate the user and
 * return only if authentication is successful
 */
static void
do_authloop(Authctxt *authctxt)
{
	int authenticated = 0;
	char info[1024];
	int prev = 0, type = 0;
	const struct AuthMethod1 *meth;

	debug("Attempting authentication for %s%.100s.",
	    authctxt->valid ? "" : "invalid user ", authctxt->user);

	/* If the user has no password, accept authentication immediately. */
	if (options.password_authentication &&
#ifdef KRB5
	    (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
	    PRIVSEP(auth_password(authctxt, ""))) {
#ifdef USE_PAM
		if (options.use_pam && (PRIVSEP(do_pam_account())))
#endif
		{
			auth_log(authctxt, 1, "without authentication", "");
			return;
		}
	}

	/* Indicate that authentication is needed. */
	packet_start(SSH_SMSG_FAILURE);
	packet_send();
	packet_write_wait();

	for (;;) {
		/* default to fail */
		authenticated = 0;

		info[0] = '\0';

		/* Get a packet from the client. */
		prev = type;
		type = packet_read();

		/*
		 * If we started challenge-response authentication but the
		 * next packet is not a response to our challenge, release
		 * the resources allocated by get_challenge() (which would
		 * normally have been released by verify_response() had we
		 * received such a response)
		 */
		if (prev == SSH_CMSG_AUTH_TIS &&
		    type != SSH_CMSG_AUTH_TIS_RESPONSE)
			abandon_challenge_response(authctxt);

		if ((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
47686178	1	/* $OpenBSD: auth1.c,v 1.71 2007/09/21 08:15:29 djm Exp $ */
3c0ef626	2	/*
	3	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	4	* All rights reserved
	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".
	11	*/
	12
	13	#include "includes.h"
9108f8d9	14
	15	#include <sys/types.h>
	16
	17	#include <stdarg.h>
	18	#include <stdio.h>
	19	#include <string.h>
	20	#include <unistd.h>
	21	#include <pwd.h>
3c0ef626	22
	23	#include "xmalloc.h"
	24	#include "rsa.h"
	25	#include "ssh1.h"
	26	#include "packet.h"
	27	#include "buffer.h"
3c0ef626	28	#include "log.h"
	29	#include "servconf.h"
	30	#include "compat.h"
9108f8d9	31	#include "key.h"
9108f8d9	32	#include "hostfile.h"
3c0ef626	33	#include "auth.h"
e9a17296	34	#include "channels.h"
3c0ef626	35	#include "session.h"
3c0ef626	36	#include "uidswap.h"
9108f8d9	37	#ifdef GSSAPI
	38	#include "ssh-gss.h"
	39	#endif
700318f3	40	#include "monitor_wrap.h"
996d5e62	41	#include "buffer.h"
3c0ef626	42
	43	/* import */
	44	extern ServerOptions options;
996d5e62	45	extern Buffer loginmsg;
3c0ef626	46
665a873d	47	static int auth1_process_password(Authctxt , char , size_t);
	48	static int auth1_process_rsa(Authctxt , char , size_t);
	49	static int auth1_process_rhosts_rsa(Authctxt , char , size_t);
	50	static int auth1_process_tis_challenge(Authctxt , char , size_t);
	51	static int auth1_process_tis_response(Authctxt , char , size_t);
	52
	53	static char client_user = NULL; / Used to fill in remote user for PAM */
	54
	55	struct AuthMethod1 {
	56	int type;
	57	char *name;
	58	int *enabled;
	59	int (method)(Authctxt , char *, size_t);
	60	};
	61
	62	const struct AuthMethod1 auth1_methods[] = {
	63	{
	64	SSH_CMSG_AUTH_PASSWORD, "password",
	65	&options.password_authentication, auth1_process_password
	66	},
	67	{
	68	SSH_CMSG_AUTH_RSA, "rsa",
	69	&options.rsa_authentication, auth1_process_rsa
	70	},
	71	{
	72	SSH_CMSG_AUTH_RHOSTS_RSA, "rhosts-rsa",
	73	&options.rhosts_rsa_authentication, auth1_process_rhosts_rsa
	74	},
	75	{
	76	SSH_CMSG_AUTH_TIS, "challenge-response",
	77	&options.challenge_response_authentication,
	78	auth1_process_tis_challenge
	79	},
	80	{
	81	SSH_CMSG_AUTH_TIS_RESPONSE, "challenge-response",
	82	&options.challenge_response_authentication,
	83	auth1_process_tis_response
	84	},
	85	{ -1, NULL, NULL, NULL}
	86	};
	87
	88	static const struct AuthMethod1
	89	*lookup_authmethod1(int type)
	90	{
	91	int i;
	92
9108f8d9	93	for (i = 0; auth1_methods[i].name != NULL; i++)
665a873d	94	if (auth1_methods[i].type == type)
	95	return (&(auth1_methods[i]));
	96
	97	return (NULL);
	98	}
	99
3c0ef626	100	static char *
	101	get_authname(int type)
	102	{
665a873d	103	const struct AuthMethod1 *a;
	104	static char buf[64];
	105
	106	if ((a = lookup_authmethod1(type)) != NULL)
	107	return (a->name);
	108	snprintf(buf, sizeof(buf), "bad-auth-msg-%d", type);
	109	return (buf);
	110	}
	111
9108f8d9	112	/ARGSUSED/
665a873d	113	static int
	114	auth1_process_password(Authctxt authctxt, char info, size_t infolen)
	115	{
	116	int authenticated = 0;
	117	char *password;
	118	u_int dlen;
	119
	120	/*
	121	* Read user password. It is in plain text, but was
	122	* transmitted over the encrypted channel so it is
	123	* not visible to an outside observer.
	124	*/
	125	password = packet_get_string(&dlen);
	126	packet_check_eom();
	127
	128	/* Try authentication with the password. */
	129	authenticated = PRIVSEP(auth_password(authctxt, password));
	130
	131	memset(password, 0, dlen);
	132	xfree(password);
	133
	134	return (authenticated);
	135	}
	136
9108f8d9	137	/ARGSUSED/
665a873d	138	static int
	139	auth1_process_rsa(Authctxt authctxt, char info, size_t infolen)
	140	{
	141	int authenticated = 0;
	142	BIGNUM *n;
	143
	144	/* RSA authentication requested. */
	145	if ((n = BN_new()) == NULL)
	146	fatal("do_authloop: BN_new failed");
	147	packet_get_bignum(n);
	148	packet_check_eom();
	149	authenticated = auth_rsa(authctxt, n);
	150	BN_clear_free(n);
	151
	152	return (authenticated);
	153	}
	154
9108f8d9	155	/ARGSUSED/
665a873d	156	static int
	157	auth1_process_rhosts_rsa(Authctxt authctxt, char info, size_t infolen)
	158	{
	159	int keybits, authenticated = 0;
	160	u_int bits;
	161	Key *client_host_key;
	162	u_int ulen;
	163
	164	/*
	165	* Get client user name. Note that we just have to
	166	* trust the client; root on the client machine can
	167	* claim to be any user.
	168	*/
	169	client_user = packet_get_string(&ulen);
	170
	171	/* Get the client host key. */
	172	client_host_key = key_new(KEY_RSA1);
	173	bits = packet_get_int();
	174	packet_get_bignum(client_host_key->rsa->e);
	175	packet_get_bignum(client_host_key->rsa->n);
	176
	177	keybits = BN_num_bits(client_host_key->rsa->n);
	178	if (keybits < 0 \|\| bits != (u_int)keybits) {
	179	verbose("Warning: keysize mismatch for client_host_key: "
	180	"actual %d, announced %d",
	181	BN_num_bits(client_host_key->rsa->n), bits);
3c0ef626	182	}
665a873d	183	packet_check_eom();
	184
	185	authenticated = auth_rhosts_rsa(authctxt, client_user,
	186	client_host_key);
	187	key_free(client_host_key);
	188
	189	snprintf(info, infolen, " ruser %.100s", client_user);
	190
	191	return (authenticated);
	192	}
	193
9108f8d9	194	/ARGSUSED/
665a873d	195	static int
	196	auth1_process_tis_challenge(Authctxt authctxt, char info, size_t infolen)
	197	{
	198	char *challenge;
	199
	200	if ((challenge = get_challenge(authctxt)) == NULL)
	201	return (0);
	202
	203	debug("sending challenge '%s'", challenge);
	204	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
	205	packet_put_cstring(challenge);
	206	xfree(challenge);
	207	packet_send();
	208	packet_write_wait();
	209
	210	return (-1);
	211	}
	212
9108f8d9	213	/ARGSUSED/
665a873d	214	static int
	215	auth1_process_tis_response(Authctxt authctxt, char info, size_t infolen)
	216	{
	217	int authenticated = 0;
	218	char *response;
	219	u_int dlen;
	220
	221	response = packet_get_string(&dlen);
	222	packet_check_eom();
	223	authenticated = verify_response(authctxt, response);
	224	memset(response, 'r', dlen);
	225	xfree(response);
	226
	227	return (authenticated);
3c0ef626	228	}
	229
	230	/*
	231	* read packets, try to authenticate the user and
	232	* return only if authentication is successful
	233	*/
	234	static void
	235	do_authloop(Authctxt *authctxt)
	236	{
	237	int authenticated = 0;
3c0ef626	238	char info[1024];
665a873d	239	int prev = 0, type = 0;
665a873d	240	const struct AuthMethod1 *meth;
3c0ef626	241
3c0ef626	242	debug("Attempting authentication for %s%.100s.",
c9f39d2c	243	authctxt->valid ? "" : "invalid user ", authctxt->user);
3c0ef626	244
	245	/* If the user has no password, accept authentication immediately. */
	246	if (options.password_authentication &&
0fff78ff	247	#ifdef KRB5
3c0ef626	248	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
3c0ef626	249	#endif
700318f3	250	PRIVSEP(auth_password(authctxt, ""))) {
c9f39d2c	251	#ifdef USE_PAM
	252	if (options.use_pam && (PRIVSEP(do_pam_account())))
	253	#endif
	254	{
	255	auth_log(authctxt, 1, "without authentication", "");
	256	return;
	257	}
3c0ef626	258	}
	259
	260	/* Indicate that authentication is needed. */
	261	packet_start(SSH_SMSG_FAILURE);
	262	packet_send();
	263	packet_write_wait();
	264
3c0ef626	265	for (;;) {
	266	/* default to fail */
	267	authenticated = 0;
	268
	269	info[0] = '\0';
	270
	271	/* Get a packet from the client. */
0fff78ff	272	prev = type;
e9a17296	273	type = packet_read();
3c0ef626	274
0fff78ff	275	/*
	276	* If we started challenge-response authentication but the
	277	* next packet is not a response to our challenge, release
	278	* the resources allocated by get_challenge() (which would
	279	* normally have been released by verify_response() had we
	280	* received such a response)
	281	*/
	282	if (prev == SSH_CMSG_AUTH_TIS &&
	283	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	284	abandon_challenge_response(authctxt);
	285
665a873d	286	if ((meth = lookup_authmethod1(type)) == NULL) {
	287	logit("Unknown message during authentication: "
	288	"type %d", type);
	289	goto skip;
	290	}
	291
	292	if (!*(meth->enabled)) {
	293	verbose("%s authentication disabled.", meth->name);
	294	goto skip;
3c0ef626	295	}
665a873d	296
	297	authenticated = meth->method(authctxt, info, sizeof(info));
	298	if (authenticated == -1)
	299	continue; /* "postponed" */
	300
3c0ef626	301	#ifdef BSD_AUTH
	302	if (authctxt->as) {
	303	auth_close(authctxt->as);
	304	authctxt->as = NULL;
	305	}
	306	#endif
	307	if (!authctxt->valid && authenticated)
	308	fatal("INTERNAL ERROR: authenticated invalid user %s",
	309	authctxt->user);
	310
41b2f314	311	#ifdef _UNICOS
41b2f314	312	if (authenticated && cray_access_denied(authctxt->user)) {
	313	authenticated = 0;
	314	fatal("Access denied for user %s.",authctxt->user);
	315	}
	316	#endif /* _UNICOS */
	317
3c0ef626	318	#ifdef HAVE_CYGWIN
3c0ef626	319	if (authenticated &&
665a873d	320	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD,
c9f39d2c	321	authctxt->pw)) {
3c0ef626	322	packet_disconnect("Authentication rejected for uid %d.",
c9f39d2c	323	authctxt->pw == NULL ? -1 : authctxt->pw->pw_uid);
3c0ef626	324	authenticated = 0;
	325	}
	326	#else
	327	/* Special handling for root */
6a9b3198	328	if (authenticated && authctxt->pw->pw_uid == 0 &&
665a873d	329	!auth_root_allowed(meth->name)) {
665a873d	330	authenticated = 0;
996d5e62	331	# ifdef SSH_AUDIT_EVENTS
	332	PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED));
	333	# endif
	334	}
3c0ef626	335	#endif
0fff78ff	336
3c0ef626	337	#ifdef USE_PAM
cdd66111	338	if (options.use_pam && authenticated &&
996d5e62	339	!PRIVSEP(do_pam_account())) {
	340	char *msg;
	341	size_t len;
	342
	343	error("Access denied for user %s by PAM account "
665a873d	344	"configuration", authctxt->user);
996d5e62	345	len = buffer_len(&loginmsg);
	346	buffer_append(&loginmsg, "\0", 1);
	347	msg = buffer_ptr(&loginmsg);
	348	/* strip trailing newlines */
	349	if (len > 0)
	350	while (len > 0 && msg[--len] == '\n')
	351	msg[len] = '\0';
	352	else
	353	msg = "Access denied.";
	354	packet_disconnect(msg);
	355	}
3c0ef626	356	#endif
3c0ef626	357
665a873d	358	skip:
3c0ef626	359	/* Log before sending the reply */
	360	auth_log(authctxt, authenticated, get_authname(type), info);
	361
	362	if (client_user != NULL) {
	363	xfree(client_user);
	364	client_user = NULL;
	365	}
	366
	367	if (authenticated)
	368	return;
	369
996d5e62	370	if (authctxt->failures++ > options.max_authtries) {
	371	#ifdef SSH_AUDIT_EVENTS
	372	PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES));
	373	#endif
3c0ef626	374	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
996d5e62	375	}
3c0ef626	376
	377	packet_start(SSH_SMSG_FAILURE);
	378	packet_send();
	379	packet_write_wait();
	380	}
	381	}
	382
	383	/*
	384	* Performs authentication of an incoming connection. Session key has already
	385	* been exchanged and encryption is enabled.
	386	*/
cdd66111	387	void
cdd66111	388	do_authentication(Authctxt *authctxt)
3c0ef626	389	{
3c0ef626	390	u_int ulen;
700318f3	391	char user, style = NULL;
3c0ef626	392
3c0ef626	393	/* Get the name of the user that we wish to log in as. */
e9a17296	394	packet_read_expect(SSH_CMSG_USER);
3c0ef626	395
	396	/* Get the user name. */
	397	user = packet_get_string(&ulen);
e9a17296	398	packet_check_eom();
3c0ef626	399
	400	if ((style = strchr(user, ':')) != NULL)
	401	*style++ = '\0';
	402
3c0ef626	403	authctxt->user = user;
	404	authctxt->style = style;
	405
	406	/* Verify that the user is a valid user. */
700318f3	407	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
3c0ef626	408	authctxt->valid = 1;
0fff78ff	409	else {
c9f39d2c	410	debug("do_authentication: invalid user %s", user);
0fff78ff	411	authctxt->pw = fakepw();
0fff78ff	412	}
3c0ef626	413
c9f39d2c	414	setproctitle("%s%s", authctxt->valid ? user : "unknown",
700318f3	415	use_privsep ? " [net]" : "");
3c0ef626	416
3c0ef626	417	#ifdef USE_PAM
0fff78ff	418	if (options.use_pam)
99be0775	419	PRIVSEP(start_pam(authctxt));
3c0ef626	420	#endif
	421
	422	/*
	423	* If we are not running as root, the user must have the same uid as
665a873d	424	* the server.
3c0ef626	425	*/
3c0ef626	426	#ifndef HAVE_CYGWIN
700318f3	427	if (!use_privsep && getuid() != 0 && authctxt->pw &&
700318f3	428	authctxt->pw->pw_uid != getuid())
3c0ef626	429	packet_disconnect("Cannot change user when server not running as root.");
	430	#endif
	431
	432	/*
	433	* Loop until the user has been authenticated or the connection is
	434	* closed, do_authloop() returns only if authentication is successful
	435	*/
	436	do_authloop(authctxt);
	437
	438	/* The user has been authenticated and accepted. */
	439	packet_start(SSH_SMSG_SUCCESS);
	440	packet_send();
	441	packet_write_wait();
3c0ef626	442	}