[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"
RCSID("$OpenBSD: auth1.c,v 1.50 2003/08/13 08:46:30 markus Exp $");

#include "xmalloc.h"
#include "rsa.h"
#include "ssh1.h"
#include "packet.h"
#include "buffer.h"
#include "mpaux.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"

/* import */
extern ServerOptions options;

/*
 * convert ssh auth msg type into description
 */
static char *
get_authname(int type)
{
	static char buf[1024];
	switch (type) {
	case SSH_CMSG_AUTH_PASSWORD:
		return "password";
	case SSH_CMSG_AUTH_RSA:
		return "rsa";
	case SSH_CMSG_AUTH_RHOSTS_RSA:
		return "rhosts-rsa";
	case SSH_CMSG_AUTH_RHOSTS:
		return "rhosts";
	case SSH_CMSG_AUTH_TIS:
	case SSH_CMSG_AUTH_TIS_RESPONSE:
		return "challenge-response";
#ifdef KRB5
	case SSH_CMSG_AUTH_KERBEROS:
		return "kerberos";
#endif
	}
	snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
	return buf;
}

/*
 * read packets, try to authenticate the user and
 * return only if authentication is successful
 */
static void
do_authloop(Authctxt *authctxt)
{
	int authenticated = 0;
	u_int bits;
	Key *client_host_key;
	BIGNUM *n;
	char *client_user, *password;
	char info[1024];
	u_int dlen;
	u_int ulen;
	int prev, type = 0;
	struct passwd *pw = authctxt->pw;

	debug("Attempting authentication for %s%.100s.",
	    authctxt->valid ? "" : "illegal 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, ""))) {
		auth_log(authctxt, 1, "without authentication", "");
		return;
	}

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

	client_user = NULL;

	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);

		/* Process the packet. */
		switch (type) {

#ifdef KRB5
		case SSH_CMSG_AUTH_KERBEROS:
			if (!options.kerberos_authentication) {
				verbose("Kerberos authentication disabled.");
			} else {
				char *kdata = packet_get_string(&dlen);
				packet_check_eom();

				if (kdata[0] != 4) { /* KRB_PROT_VERSION */
					krb5_data tkt, reply;
					tkt.length = dlen;
					tkt.data = kdata;

					if (PRIVSEP(auth_krb5(authctxt, &tkt,
					    &client_user, &reply))) {
						authenticated = 1;
						snprintf(info, sizeof(info),
						    " tktuser %.100s",
						    client_user);

 						/* Send response to client */
 						packet_start(
						    SSH_SMSG_AUTH_KERBEROS_RESPONSE);
 						packet_put_string((char *)
						    reply.data, reply.length);
 						packet_send();
 						packet_write_wait();

 						if (reply.length)
 							xfree(reply.data);
					}
				}
				xfree(kdata);
			}
			break;
		case SSH_CMSG_HAVE_KERBEROS_TGT:
			packet_send_debug("Kerberos TGT passing disabled before authentication.");
			break;
#endif

		case SSH_CMSG_AUTH_RHOSTS_RSA:
			if (!options.rhosts_rsa_authentication) {
				verbose("Rhosts with RSA authentication disabled.");
				break;
			}
			/*
			 * 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);

			if (bits != BN_num_bits(client_host_key->rsa->n))
				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(pw, client_user,
			    client_host_key);
			key_free(client_host_key);

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

		case SSH_CMSG_AUTH_RSA:
			if (!options.rsa_authentication) {
				verbose("RSA authentication disabled.");
				break;
			}
			/* RSA authentication requested. */
			if ((n = BN_new()) == NULL)
				fatal("do_authloop: BN_new failed");
			packet_get_bignum(n);
			packet_check_eom();
			authenticated = auth_rsa(pw, n);
			BN_clear_free(n);
			break;

		case SSH_CMSG_AUTH_PASSWORD:
			if (!options.password_authentication) {
				verbose("Password authentication disabled.");
				break;
			}
			/*
			 * 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, strlen(password));
			xfree(password);
			break;

		case SSH_CMSG_AUTH_TIS:
			debug("rcvd SSH_CMSG_AUTH_TIS");
			if (options.challenge_response_authentication == 1) {
				char *challenge = get_challenge(authctxt);
				if (challenge != NULL) {
					debug("sending challenge '%s'", challenge);
					packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
					packet_put_cstring(challenge);
					xfree(challenge);
					packet_send();
					packet_write_wait();
					continue;
				}
			}
			break;
		case SSH_CMSG_AUTH_TIS_RESPONSE:
			debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
			if (options.challenge_response_authentication == 1) {
				char *response = packet_get_string(&dlen);
				packet_check_eom();
				authenticated = verify_response(authctxt, response);
				memset(response, 'r', dlen);
				xfree(response);
			}
			break;

		default:
			/*
			 * Any unknown messages will be ignored (and failure
			 * returned) during authentication.
			 */
			logit("Unknown message during authentication: type %d", type);
			break;
		}
#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, pw)) {
			packet_disconnect("Authentication rejected for uid %d.",
			pw == NULL ? -1 : pw->pw_uid);
			authenticated = 0;
		}
#else
		/* Special handling for root */
		if (authenticated && authctxt->pw->pw_uid == 0 &&
		    !auth_root_allowed(get_authname(type)))
			authenticated = 0;
#endif

#ifdef USE_PAM
		if (options.use_pam && authenticated && 
		    !PRIVSEP(do_pam_account()))
			authenticated = 0;
#endif

		/* 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++ > AUTH_FAIL_MAX)
			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.
 */
Authctxt *
do_authentication(void)
{
	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';

#ifdef KRB5
	/* XXX - SSH.com Kerberos v5 braindeath. */
	if ((datafellows & SSH_BUG_K5USER) &&
	    options.kerberos_authentication) {
		char *p;
		if ((p = strchr(user, '@')) != NULL)
			*p = '\0';
	}
#endif

	authctxt = authctxt_new();
	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: illegal user %s", user);

	setproctitle("%s%s", authctxt->pw ? user : "unknown",
	    use_privsep ? " [net]" : "");

#ifdef USE_PAM
	if (options.use_pam)
		PRIVSEP(start_pam(user));
#endif

	/*
	 * If we are not running as root, the user must have the same uid as
	 * the server. (Unless you are running Windows)
	 */
#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();

	return (authctxt);
}
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"
0598d99d	13	RCSID("$OpenBSD: auth1.c,v 1.50 2003/08/13 08:46:30 markus Exp $");
94ec8c6b	14
a306f2dd	15	#include "xmalloc.h"
a306f2dd	16	#include "rsa.h"
42f11eb2	17	#include "ssh1.h"
a306f2dd	18	#include "packet.h"
a306f2dd	19	#include "buffer.h"
a306f2dd	20	#include "mpaux.h"
42f11eb2	21	#include "log.h"
a306f2dd	22	#include "servconf.h"
	23	#include "compat.h"
	24	#include "auth.h"
7899c98f	25	#include "channels.h"
a306f2dd	26	#include "session.h"
ced49be2	27	#include "uidswap.h"
1853d1ef	28	#include "monitor_wrap.h"
a306f2dd	29
	30	/* import */
	31	extern ServerOptions options;
94ec8c6b	32
a306f2dd	33	/*
	34	* convert ssh auth msg type into description
	35	*/
396c147e	36	static char *
a306f2dd	37	get_authname(int type)
	38	{
	39	static char buf[1024];
	40	switch (type) {
	41	case SSH_CMSG_AUTH_PASSWORD:
	42	return "password";
	43	case SSH_CMSG_AUTH_RSA:
	44	return "rsa";
	45	case SSH_CMSG_AUTH_RHOSTS_RSA:
	46	return "rhosts-rsa";
	47	case SSH_CMSG_AUTH_RHOSTS:
	48	return "rhosts";
59c97189	49	case SSH_CMSG_AUTH_TIS:
	50	case SSH_CMSG_AUTH_TIS_RESPONSE:
	51	return "challenge-response";
1c590258	52	#ifdef KRB5
a306f2dd	53	case SSH_CMSG_AUTH_KERBEROS:
a306f2dd	54	return "kerberos";
a306f2dd	55	#endif
	56	}
	57	snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
	58	return buf;
	59	}
	60
	61	/*
59c97189	62	* read packets, try to authenticate the user and
59c97189	63	* return only if authentication is successful
a306f2dd	64	*/
396c147e	65	static void
59c97189	66	do_authloop(Authctxt *authctxt)
a306f2dd	67	{
94ec8c6b	68	int authenticated = 0;
1e3b8b07	69	u_int bits;
b775c6f2	70	Key *client_host_key;
a306f2dd	71	BIGNUM *n;
94ec8c6b	72	char client_user, password;
59c97189	73	char info[1024];
1e3b8b07	74	u_int dlen;
1e3b8b07	75	u_int ulen;
05114c74	76	int prev, type = 0;
59c97189	77	struct passwd *pw = authctxt->pw;
	78
	79	debug("Attempting authentication for %s%.100s.",
184eed6a	80	authctxt->valid ? "" : "illegal user ", authctxt->user);
59c97189	81
	82	/* If the user has no password, accept authentication immediately. */
	83	if (options.password_authentication &&
1c590258	84	#ifdef KRB5
59c97189	85	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	86	#endif
1853d1ef	87	PRIVSEP(auth_password(authctxt, ""))) {
59c97189	88	auth_log(authctxt, 1, "without authentication", "");
	89	return;
	90	}
a306f2dd	91
	92	/* Indicate that authentication is needed. */
	93	packet_start(SSH_SMSG_FAILURE);
	94	packet_send();
	95	packet_write_wait();
	96
94ec8c6b	97	client_user = NULL;
94ec8c6b	98
59c97189	99	for (;;) {
94ec8c6b	100	/* default to fail */
	101	authenticated = 0;
	102
59c97189	103	info[0] = '\0';
a306f2dd	104
a306f2dd	105	/* Get a packet from the client. */
05114c74	106	prev = type;
54a5250f	107	type = packet_read();
a306f2dd	108
05114c74	109	/*
	110	* If we started challenge-response authentication but the
	111	* next packet is not a response to our challenge, release
	112	* the resources allocated by get_challenge() (which would
	113	* normally have been released by verify_response() had we
	114	* received such a response)
	115	*/
	116	if (prev == SSH_CMSG_AUTH_TIS &&
	117	type != SSH_CMSG_AUTH_TIS_RESPONSE)
	118	abandon_challenge_response(authctxt);
	119
a306f2dd	120	/* Process the packet. */
a306f2dd	121	switch (type) {
a306f2dd	122
1c590258	123	#ifdef KRB5
a306f2dd	124	case SSH_CMSG_AUTH_KERBEROS:
a306f2dd	125	if (!options.kerberos_authentication) {
a306f2dd	126	verbose("Kerberos authentication disabled.");
a306f2dd	127	} else {
ced49be2	128	char *kdata = packet_get_string(&dlen);
95500969	129	packet_check_eom();
184eed6a	130
1c590258	131	if (kdata[0] != 4) { /* KRB_PROT_VERSION */
696f6bef	132	krb5_data tkt, reply;
ced49be2	133	tkt.length = dlen;
ced49be2	134	tkt.data = kdata;
184eed6a	135
696f6bef	136	if (PRIVSEP(auth_krb5(authctxt, &tkt,
696f6bef	137	&client_user, &reply))) {
ced49be2	138	authenticated = 1;
	139	snprintf(info, sizeof(info),
	140	" tktuser %.100s",
	141	client_user);
b77a87e5	142
696f6bef	143	/* Send response to client */
	144	packet_start(
	145	SSH_SMSG_AUTH_KERBEROS_RESPONSE);
	146	packet_put_string((char *)
	147	reply.data, reply.length);
	148	packet_send();
	149	packet_write_wait();
	150
	151	if (reply.length)
	152	xfree(reply.data);
ced49be2	153	}
a306f2dd	154	}
59c97189	155	xfree(kdata);
a306f2dd	156	}
a306f2dd	157	break;
ced49be2	158	case SSH_CMSG_HAVE_KERBEROS_TGT:
	159	packet_send_debug("Kerberos TGT passing disabled before authentication.");
	160	break;
1c590258	161	#endif
184eed6a	162
a306f2dd	163	case SSH_CMSG_AUTH_RHOSTS_RSA:
	164	if (!options.rhosts_rsa_authentication) {
	165	verbose("Rhosts with RSA authentication disabled.");
	166	break;
	167	}
	168	/*
	169	* Get client user name. Note that we just have to
	170	* trust the client; root on the client machine can
	171	* claim to be any user.
	172	*/
	173	client_user = packet_get_string(&ulen);
	174
	175	/* Get the client host key. */
b775c6f2	176	client_host_key = key_new(KEY_RSA1);
a306f2dd	177	bits = packet_get_int();
20b279e6	178	packet_get_bignum(client_host_key->rsa->e);
20b279e6	179	packet_get_bignum(client_host_key->rsa->n);
a306f2dd	180
b775c6f2	181	if (bits != BN_num_bits(client_host_key->rsa->n))
94ec8c6b	182	verbose("Warning: keysize mismatch for client_host_key: "
b775c6f2	183	"actual %d, announced %d",
7203d6bb	184	BN_num_bits(client_host_key->rsa->n), bits);
95500969	185	packet_check_eom();
a306f2dd	186
b775c6f2	187	authenticated = auth_rhosts_rsa(pw, client_user,
dc421aa3	188	client_host_key);
b775c6f2	189	key_free(client_host_key);
a306f2dd	190
59c97189	191	snprintf(info, sizeof info, " ruser %.100s", client_user);
a306f2dd	192	break;
	193
	194	case SSH_CMSG_AUTH_RSA:
	195	if (!options.rsa_authentication) {
	196	verbose("RSA authentication disabled.");
	197	break;
	198	}
	199	/* RSA authentication requested. */
b775c6f2	200	if ((n = BN_new()) == NULL)
b775c6f2	201	fatal("do_authloop: BN_new failed");
20b279e6	202	packet_get_bignum(n);
95500969	203	packet_check_eom();
a306f2dd	204	authenticated = auth_rsa(pw, n);
	205	BN_clear_free(n);
	206	break;
	207
	208	case SSH_CMSG_AUTH_PASSWORD:
	209	if (!options.password_authentication) {
	210	verbose("Password authentication disabled.");
	211	break;
	212	}
	213	/*
	214	* Read user password. It is in plain text, but was
	215	* transmitted over the encrypted channel so it is
	216	* not visible to an outside observer.
	217	*/
	218	password = packet_get_string(&dlen);
95500969	219	packet_check_eom();
a306f2dd	220
b4b5d644	221	/* Try authentication with the password. */
1853d1ef	222	authenticated = PRIVSEP(auth_password(authctxt, password));
a306f2dd	223
	224	memset(password, 0, strlen(password));
	225	xfree(password);
	226	break;
	227
a306f2dd	228	case SSH_CMSG_AUTH_TIS:
a306f2dd	229	debug("rcvd SSH_CMSG_AUTH_TIS");
5ba55ada	230	if (options.challenge_response_authentication == 1) {
5ba55ada	231	char *challenge = get_challenge(authctxt);
59c97189	232	if (challenge != NULL) {
59c97189	233	debug("sending challenge '%s'", challenge);
a306f2dd	234	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
59c97189	235	packet_put_cstring(challenge);
5ba55ada	236	xfree(challenge);
a306f2dd	237	packet_send();
	238	packet_write_wait();
	239	continue;
	240	}
	241	}
	242	break;
	243	case SSH_CMSG_AUTH_TIS_RESPONSE:
	244	debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
5ba55ada	245	if (options.challenge_response_authentication == 1) {
a306f2dd	246	char *response = packet_get_string(&dlen);
95500969	247	packet_check_eom();
59c97189	248	authenticated = verify_response(authctxt, response);
59c97189	249	memset(response, 'r', dlen);
a306f2dd	250	xfree(response);
	251	}
	252	break;
a306f2dd	253
	254	default:
	255	/*
	256	* Any unknown messages will be ignored (and failure
	257	* returned) during authentication.
	258	*/
bbe88b6d	259	logit("Unknown message during authentication: type %d", type);
a306f2dd	260	break;
a306f2dd	261	}
af774732	262	#ifdef BSD_AUTH
	263	if (authctxt->as) {
	264	auth_close(authctxt->as);
	265	authctxt->as = NULL;
	266	}
	267	#endif
59c97189	268	if (!authctxt->valid && authenticated)
	269	fatal("INTERNAL ERROR: authenticated invalid user %s",
	270	authctxt->user);
a306f2dd	271
ef51930f	272	#ifdef _UNICOS
ef51930f	273	if (authenticated && cray_access_denied(authctxt->user)) {
	274	authenticated = 0;
	275	fatal("Access denied for user %s.",authctxt->user);
	276	}
	277	#endif /* _UNICOS */
	278
2b87da3b	279	#ifdef HAVE_CYGWIN
2b87da3b	280	if (authenticated &&
e9571a2c	281	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
3c62e7eb	282	packet_disconnect("Authentication rejected for uid %d.",
e9571a2c	283	pw == NULL ? -1 : pw->pw_uid);
3c62e7eb	284	authenticated = 0;
3c62e7eb	285	}
3c418020	286	#else
59c97189	287	/* Special handling for root */
5d47f1d4	288	if (authenticated && authctxt->pw->pw_uid == 0 &&
15853e93	289	!auth_root_allowed(get_authname(type)))
59c97189	290	authenticated = 0;
3c418020	291	#endif
a306f2dd	292
5b9e2464	293	#ifdef USE_PAM
	294	if (options.use_pam && authenticated &&
	295	!PRIVSEP(do_pam_account()))
	296	authenticated = 0;
	297	#endif
	298
59c97189	299	/* Log before sending the reply */
	300	auth_log(authctxt, authenticated, get_authname(type), info);
	301
a306f2dd	302	if (client_user != NULL) {
	303	xfree(client_user);
	304	client_user = NULL;
	305	}
	306
94ec8c6b	307	if (authenticated)
	308	return;
	309
9a6fee8b	310	if (authctxt->failures++ > AUTH_FAIL_MAX)
59c97189	311	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
a306f2dd	312
a306f2dd	313	packet_start(SSH_SMSG_FAILURE);
	314	packet_send();
	315	packet_write_wait();
	316	}
	317	}
	318
	319	/*
	320	* Performs authentication of an incoming connection. Session key has already
	321	* been exchanged and encryption is enabled.
	322	*/
1b34c1b3	323	Authctxt *
d5bb9418	324	do_authentication(void)
a306f2dd	325	{
59c97189	326	Authctxt *authctxt;
1e3b8b07	327	u_int ulen;
f8d99a32	328	char user, style = NULL;
a306f2dd	329
a306f2dd	330	/* Get the name of the user that we wish to log in as. */
54a5250f	331	packet_read_expect(SSH_CMSG_USER);
a306f2dd	332
	333	/* Get the user name. */
	334	user = packet_get_string(&ulen);
95500969	335	packet_check_eom();
a306f2dd	336
59c97189	337	if ((style = strchr(user, ':')) != NULL)
ced49be2	338	*style++ = '\0';
59c97189	339
f8d99a32	340	#ifdef KRB5
ced49be2	341	/* XXX - SSH.com Kerberos v5 braindeath. */
f8d99a32	342	if ((datafellows & SSH_BUG_K5USER) &&
	343	options.kerberos_authentication) {
	344	char *p;
	345	if ((p = strchr(user, '@')) != NULL)
	346	*p = '\0';
	347	}
	348	#endif
184eed6a	349
59c97189	350	authctxt = authctxt_new();
	351	authctxt->user = user;
	352	authctxt->style = style;
	353
a306f2dd	354	/* Verify that the user is a valid user. */
5f1f36b5	355	if ((authctxt->pw = PRIVSEP(getpwnamallow(user))) != NULL)
59c97189	356	authctxt->valid = 1;
5f1f36b5	357	else
59c97189	358	debug("do_authentication: illegal user %s", user);
a306f2dd	359
5f1f36b5	360	setproctitle("%s%s", authctxt->pw ? user : "unknown",
1853d1ef	361	use_privsep ? " [net]" : "");
6172e290	362
a306f2dd	363	#ifdef USE_PAM
7fceb20d	364	if (options.use_pam)
7fceb20d	365	PRIVSEP(start_pam(user));
a306f2dd	366	#endif
	367
	368	/*
	369	* If we are not running as root, the user must have the same uid as
94ec8c6b	370	* the server. (Unless you are running Windows)
a306f2dd	371	*/
94ec8c6b	372	#ifndef HAVE_CYGWIN
5f1f36b5	373	if (!use_privsep && getuid() != 0 && authctxt->pw &&
5f1f36b5	374	authctxt->pw->pw_uid != getuid())
a306f2dd	375	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	376	#endif
a306f2dd	377
59c97189	378	/*
b4b5d644	379	* Loop until the user has been authenticated or the connection is
	380	* closed, do_authloop() returns only if authentication is successful
	381	*/
59c97189	382	do_authloop(authctxt);
a306f2dd	383
a306f2dd	384	/* The user has been authenticated and accepted. */
94ec8c6b	385	packet_start(SSH_SMSG_SUCCESS);
	386	packet_send();
	387	packet_write_wait();
59c97189	388
1b34c1b3	389	return (authctxt);
a306f2dd	390	}