[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 1.28 2001/12/25 18:53:00 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 "session.h"
#include "misc.h"
#include "uidswap.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";
#if defined(KRB4) || defined(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;
	RSA *client_host_key;
	BIGNUM *n;
	char *client_user, *password;
	char info[1024];
	u_int dlen;
	int plen, nlen, elen;
	u_int ulen;
	int 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 &&
#if defined(KRB4) || defined(KRB5)
	    (!options.kerberos_authentication || options.kerberos_or_local_passwd) &&
#endif
#ifdef USE_PAM
	    auth_pam_password(pw, "")) {
#elif defined(HAVE_OSF_SIA)
	    0) {
#else
	    auth_password(authctxt, "")) {
#endif
		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. */
		type = packet_read(&plen);

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

#if defined(KRB4) || defined(KRB5)
		case SSH_CMSG_AUTH_KERBEROS:
			if (!options.kerberos_authentication) {
				verbose("Kerberos authentication disabled.");
			} else {
				char *kdata = packet_get_string(&dlen);

				packet_integrity_check(plen, 4 + dlen, type);

				if (kdata[0] == 4) { /* KRB_PROT_VERSION */
#ifdef KRB4
					KTEXT_ST tkt;

					tkt.length = dlen;
					if (tkt.length < MAX_KTXT_LEN)
						memcpy(tkt.dat, kdata, tkt.length);

					if (auth_krb4(authctxt, &tkt, &client_user)) {
						authenticated = 1;
						snprintf(info, sizeof(info),
						    " tktuser %.100s",
						    client_user);
					}
#endif /* KRB4 */
				} else {
#ifdef KRB5
					krb5_data tkt;
					tkt.length = dlen;
					tkt.data = kdata;

					if (auth_krb5(authctxt, &tkt, &client_user)) {
						authenticated = 1;
						snprintf(info, sizeof(info),
						    " tktuser %.100s",
						    client_user);
					}
#endif /* KRB5 */
				}
				xfree(kdata);
			}
			break;
#endif /* KRB4 || KRB5 */

#if defined(AFS) || defined(KRB5)
			/* XXX - punt on backward compatibility here. */
		case SSH_CMSG_HAVE_KERBEROS_TGT:
			packet_send_debug("Kerberos TGT passing disabled before authentication.");
			break;
#ifdef AFS
		case SSH_CMSG_HAVE_AFS_TOKEN:
			packet_send_debug("AFS token passing disabled before authentication.");
			break;
#endif /* AFS */
#endif /* AFS || KRB5 */

		case SSH_CMSG_AUTH_RHOSTS:
			if (!options.rhosts_authentication) {
				verbose("Rhosts authentication disabled.");
				break;
			}
			/*
			 * Get client user name.  Note that we just have to
			 * trust the client; this is one reason why rhosts
			 * authentication is insecure. (Another is
			 * IP-spoofing on a local network.)
			 */
			client_user = packet_get_string(&ulen);
			packet_integrity_check(plen, 4 + ulen, type);

			/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
			authenticated = auth_rhosts(pw, client_user);

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

		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 = RSA_new();
			if (client_host_key == NULL)
				fatal("RSA_new failed");
			client_host_key->e = BN_new();
			client_host_key->n = BN_new();
			if (client_host_key->e == NULL || client_host_key->n == NULL)
				fatal("BN_new failed");
			bits = packet_get_int();
			packet_get_bignum(client_host_key->e, &elen);
			packet_get_bignum(client_host_key->n, &nlen);

			if (bits != BN_num_bits(client_host_key->n))
				verbose("Warning: keysize mismatch for client_host_key: "
				    "actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
			packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);

			authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
			RSA_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. */
			n = BN_new();
			if (n == NULL)
				fatal("BN_new failed");
			packet_get_bignum(n, &nlen);
			packet_integrity_check(plen, nlen, type);
			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_integrity_check(plen, 4 + dlen, type);

#ifdef USE_PAM
			/* Do PAM auth with password */
			authenticated = auth_pam_password(pw, password);
#elif defined(HAVE_OSF_SIA)
			/* Do SIA auth with password */
			authenticated = auth_sia_password(authctxt->user, 
			    password);
#else /* !USE_PAM && !HAVE_OSF_SIA */
			/* Try authentication with the password. */
			authenticated = auth_password(authctxt, password);
#endif /* USE_PAM */

			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);
				debug("got response '%s'", response);
				packet_integrity_check(plen, 4 + dlen, type);
				authenticated = verify_response(authctxt, response);
				memset(response, 'r', dlen);
				xfree(response);
			}
			break;

		default:
			/*
			 * Any unknown messages will be ignored (and failure
			 * returned) during authentication.
			 */
			log("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 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 (authenticated && !do_pam_account(pw->pw_name, client_user))
			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) {
#ifdef WITH_AIXAUTHENTICATE
			loginfailed(authctxt->user,
			    get_canonical_hostname(options.reverse_mapping_check),
			    "ssh");
#endif /* WITH_AIXAUTHENTICATE */
			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(void)
{
	Authctxt *authctxt;
	struct passwd *pw;
	int plen;
	u_int ulen;
	char *p, *user, *style = NULL;

	/* Get the name of the user that we wish to log in as. */
	packet_read_expect(&plen, SSH_CMSG_USER);

	/* Get the user name. */
	user = packet_get_string(&ulen);
	packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);

	if ((style = strchr(user, ':')) != NULL)
		*style++ = '\0';

	/* XXX - SSH.com Kerberos v5 braindeath. */
	if ((p = strchr(user, '@')) != NULL)
		*p = '\0';

	authctxt = authctxt_new();
	authctxt->user = user;
	authctxt->style = style;

	/* Verify that the user is a valid user. */
	pw = getpwnam(user);
	if (pw && allowed_user(pw)) {
		authctxt->valid = 1;
		pw = pwcopy(pw);
	} else {
		debug("do_authentication: illegal user %s", user);
		pw = NULL;
	}
	authctxt->pw = pw;

	setproctitle("%s", pw ? user : "unknown");

#ifdef USE_PAM
	if (pw)
		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 (getuid() != 0 && pw && 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();

	/* Perform session preparation. */
	do_authenticated(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"
45c49544	13	RCSID("$OpenBSD: auth1.c,v 1.28 2001/12/25 18:53:00 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"
	25	#include "session.h"
3b1a83df	26	#include "misc.h"
ced49be2	27	#include "uidswap.h"
a306f2dd	28
	29	/* import */
	30	extern ServerOptions options;
94ec8c6b	31
a306f2dd	32	/*
	33	* convert ssh auth msg type into description
	34	*/
396c147e	35	static char *
a306f2dd	36	get_authname(int type)
	37	{
	38	static char buf[1024];
	39	switch (type) {
	40	case SSH_CMSG_AUTH_PASSWORD:
	41	return "password";
	42	case SSH_CMSG_AUTH_RSA:
	43	return "rsa";
	44	case SSH_CMSG_AUTH_RHOSTS_RSA:
	45	return "rhosts-rsa";
	46	case SSH_CMSG_AUTH_RHOSTS:
	47	return "rhosts";
59c97189	48	case SSH_CMSG_AUTH_TIS:
	49	case SSH_CMSG_AUTH_TIS_RESPONSE:
	50	return "challenge-response";
ced49be2	51	#if defined(KRB4) \|\| defined(KRB5)
a306f2dd	52	case SSH_CMSG_AUTH_KERBEROS:
a306f2dd	53	return "kerberos";
a306f2dd	54	#endif
	55	}
	56	snprintf(buf, sizeof buf, "bad-auth-msg-%d", type);
	57	return buf;
	58	}
	59
	60	/*
59c97189	61	* read packets, try to authenticate the user and
59c97189	62	* return only if authentication is successful
a306f2dd	63	*/
396c147e	64	static void
59c97189	65	do_authloop(Authctxt *authctxt)
a306f2dd	66	{
94ec8c6b	67	int authenticated = 0;
1e3b8b07	68	u_int bits;
a306f2dd	69	RSA *client_host_key;
a306f2dd	70	BIGNUM *n;
94ec8c6b	71	char client_user, password;
59c97189	72	char info[1024];
1e3b8b07	73	u_int dlen;
a306f2dd	74	int plen, nlen, elen;
1e3b8b07	75	u_int ulen;
a306f2dd	76	int 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 &&
ced49be2	84	#if defined(KRB4) \|\| defined(KRB5)
59c97189	85	(!options.kerberos_authentication \|\| options.kerberos_or_local_passwd) &&
59c97189	86	#endif
f4ebf0e8	87	#ifdef USE_PAM
8d60e965	88	auth_pam_password(pw, "")) {
b7ccb051	89	#elif defined(HAVE_OSF_SIA)
b7ccb051	90	0) {
59c97189	91	#else
af774732	92	auth_password(authctxt, "")) {
59c97189	93	#endif
	94	auth_log(authctxt, 1, "without authentication", "");
	95	return;
	96	}
a306f2dd	97
	98	/* Indicate that authentication is needed. */
	99	packet_start(SSH_SMSG_FAILURE);
	100	packet_send();
	101	packet_write_wait();
	102
94ec8c6b	103	client_user = NULL;
94ec8c6b	104
59c97189	105	for (;;) {
94ec8c6b	106	/* default to fail */
	107	authenticated = 0;
	108
59c97189	109	info[0] = '\0';
a306f2dd	110
	111	/* Get a packet from the client. */
	112	type = packet_read(&plen);
	113
	114	/* Process the packet. */
	115	switch (type) {
a306f2dd	116
ced49be2	117	#if defined(KRB4) \|\| defined(KRB5)
a306f2dd	118	case SSH_CMSG_AUTH_KERBEROS:
a306f2dd	119	if (!options.kerberos_authentication) {
a306f2dd	120	verbose("Kerberos authentication disabled.");
a306f2dd	121	} else {
ced49be2	122	char *kdata = packet_get_string(&dlen);
184eed6a	123
ced49be2	124	packet_integrity_check(plen, 4 + dlen, type);
184eed6a	125
ced49be2	126	if (kdata[0] == 4) { /* KRB_PROT_VERSION */
	127	#ifdef KRB4
	128	KTEXT_ST tkt;
184eed6a	129
ced49be2	130	tkt.length = dlen;
	131	if (tkt.length < MAX_KTXT_LEN)
	132	memcpy(tkt.dat, kdata, tkt.length);
184eed6a	133
ced49be2	134	if (auth_krb4(authctxt, &tkt, &client_user)) {
	135	authenticated = 1;
	136	snprintf(info, sizeof(info),
	137	" tktuser %.100s",
	138	client_user);
94ec8c6b	139	}
ced49be2	140	#endif /* KRB4 */
	141	} else {
	142	#ifdef KRB5
	143	krb5_data tkt;
	144	tkt.length = dlen;
	145	tkt.data = kdata;
184eed6a	146
ced49be2	147	if (auth_krb5(authctxt, &tkt, &client_user)) {
	148	authenticated = 1;
	149	snprintf(info, sizeof(info),
	150	" tktuser %.100s",
	151	client_user);
ced49be2	152	}
ced49be2	153	#endif /* KRB5 */
a306f2dd	154	}
59c97189	155	xfree(kdata);
a306f2dd	156	}
a306f2dd	157	break;
ced49be2	158	#endif /* KRB4 \|\| KRB5 */
184eed6a	159
ced49be2	160	#if defined(AFS) \|\| defined(KRB5)
	161	/* XXX - punt on backward compatibility here. */
	162	case SSH_CMSG_HAVE_KERBEROS_TGT:
	163	packet_send_debug("Kerberos TGT passing disabled before authentication.");
	164	break;
	165	#ifdef AFS
	166	case SSH_CMSG_HAVE_AFS_TOKEN:
	167	packet_send_debug("AFS token passing disabled before authentication.");
	168	break;
	169	#endif /* AFS */
	170	#endif /* AFS \|\| KRB5 */
184eed6a	171
a306f2dd	172	case SSH_CMSG_AUTH_RHOSTS:
	173	if (!options.rhosts_authentication) {
	174	verbose("Rhosts authentication disabled.");
	175	break;
	176	}
	177	/*
	178	* Get client user name. Note that we just have to
	179	* trust the client; this is one reason why rhosts
	180	* authentication is insecure. (Another is
	181	* IP-spoofing on a local network.)
	182	*/
	183	client_user = packet_get_string(&ulen);
	184	packet_integrity_check(plen, 4 + ulen, type);
	185
94ec8c6b	186	/* Try to authenticate using /etc/hosts.equiv and .rhosts. */
a306f2dd	187	authenticated = auth_rhosts(pw, client_user);
a306f2dd	188
59c97189	189	snprintf(info, sizeof info, " ruser %.100s", client_user);
a306f2dd	190	break;
	191
	192	case SSH_CMSG_AUTH_RHOSTS_RSA:
	193	if (!options.rhosts_rsa_authentication) {
	194	verbose("Rhosts with RSA authentication disabled.");
	195	break;
	196	}
	197	/*
	198	* Get client user name. Note that we just have to
	199	* trust the client; root on the client machine can
	200	* claim to be any user.
	201	*/
	202	client_user = packet_get_string(&ulen);
	203
	204	/* Get the client host key. */
	205	client_host_key = RSA_new();
	206	if (client_host_key == NULL)
	207	fatal("RSA_new failed");
	208	client_host_key->e = BN_new();
	209	client_host_key->n = BN_new();
	210	if (client_host_key->e == NULL \|\| client_host_key->n == NULL)
	211	fatal("BN_new failed");
	212	bits = packet_get_int();
	213	packet_get_bignum(client_host_key->e, &elen);
	214	packet_get_bignum(client_host_key->n, &nlen);
	215
	216	if (bits != BN_num_bits(client_host_key->n))
94ec8c6b	217	verbose("Warning: keysize mismatch for client_host_key: "
0b242b12	218	"actual %d, announced %d", BN_num_bits(client_host_key->n), bits);
a306f2dd	219	packet_integrity_check(plen, (4 + ulen) + 4 + elen + nlen, type);
	220
	221	authenticated = auth_rhosts_rsa(pw, client_user, client_host_key);
	222	RSA_free(client_host_key);
	223
59c97189	224	snprintf(info, sizeof info, " ruser %.100s", client_user);
a306f2dd	225	break;
	226
	227	case SSH_CMSG_AUTH_RSA:
	228	if (!options.rsa_authentication) {
	229	verbose("RSA authentication disabled.");
	230	break;
	231	}
	232	/* RSA authentication requested. */
	233	n = BN_new();
45c49544	234	if (n == NULL)
45c49544	235	fatal("BN_new failed");
a306f2dd	236	packet_get_bignum(n, &nlen);
	237	packet_integrity_check(plen, nlen, type);
	238	authenticated = auth_rsa(pw, n);
	239	BN_clear_free(n);
	240	break;
	241
	242	case SSH_CMSG_AUTH_PASSWORD:
	243	if (!options.password_authentication) {
	244	verbose("Password authentication disabled.");
	245	break;
	246	}
	247	/*
	248	* Read user password. It is in plain text, but was
	249	* transmitted over the encrypted channel so it is
	250	* not visible to an outside observer.
	251	*/
	252	password = packet_get_string(&dlen);
	253	packet_integrity_check(plen, 4 + dlen, type);
	254
	255	#ifdef USE_PAM
	256	/* Do PAM auth with password */
	257	authenticated = auth_pam_password(pw, password);
4d33e531	258	#elif defined(HAVE_OSF_SIA)
4d33e531	259	/* Do SIA auth with password */
b7ccb051	260	authenticated = auth_sia_password(authctxt->user,
b7ccb051	261	password);
4d33e531	262	#else /* !USE_PAM && !HAVE_OSF_SIA */
b4b5d644	263	/* Try authentication with the password. */
af774732	264	authenticated = auth_password(authctxt, password);
a306f2dd	265	#endif /* USE_PAM */
	266
	267	memset(password, 0, strlen(password));
	268	xfree(password);
	269	break;
	270
a306f2dd	271	case SSH_CMSG_AUTH_TIS:
a306f2dd	272	debug("rcvd SSH_CMSG_AUTH_TIS");
5ba55ada	273	if (options.challenge_response_authentication == 1) {
5ba55ada	274	char *challenge = get_challenge(authctxt);
59c97189	275	if (challenge != NULL) {
59c97189	276	debug("sending challenge '%s'", challenge);
a306f2dd	277	packet_start(SSH_SMSG_AUTH_TIS_CHALLENGE);
59c97189	278	packet_put_cstring(challenge);
5ba55ada	279	xfree(challenge);
a306f2dd	280	packet_send();
	281	packet_write_wait();
	282	continue;
	283	}
	284	}
	285	break;
	286	case SSH_CMSG_AUTH_TIS_RESPONSE:
	287	debug("rcvd SSH_CMSG_AUTH_TIS_RESPONSE");
5ba55ada	288	if (options.challenge_response_authentication == 1) {
a306f2dd	289	char *response = packet_get_string(&dlen);
59c97189	290	debug("got response '%s'", response);
a306f2dd	291	packet_integrity_check(plen, 4 + dlen, type);
59c97189	292	authenticated = verify_response(authctxt, response);
59c97189	293	memset(response, 'r', dlen);
a306f2dd	294	xfree(response);
	295	}
	296	break;
a306f2dd	297
	298	default:
	299	/*
	300	* Any unknown messages will be ignored (and failure
	301	* returned) during authentication.
	302	*/
	303	log("Unknown message during authentication: type %d", type);
	304	break;
	305	}
af774732	306	#ifdef BSD_AUTH
	307	if (authctxt->as) {
	308	auth_close(authctxt->as);
	309	authctxt->as = NULL;
	310	}
	311	#endif
59c97189	312	if (!authctxt->valid && authenticated)
	313	fatal("INTERNAL ERROR: authenticated invalid user %s",
	314	authctxt->user);
a306f2dd	315
2b87da3b	316	#ifdef HAVE_CYGWIN
2b87da3b	317	if (authenticated &&
e9571a2c	318	!check_nt_auth(type == SSH_CMSG_AUTH_PASSWORD, pw)) {
3c62e7eb	319	packet_disconnect("Authentication rejected for uid %d.",
e9571a2c	320	pw == NULL ? -1 : pw->pw_uid);
3c62e7eb	321	authenticated = 0;
3c62e7eb	322	}
3c418020	323	#else
59c97189	324	/* Special handling for root */
15853e93	325	if (authenticated && authctxt->pw->pw_uid == 0 &&
15853e93	326	!auth_root_allowed(get_authname(type)))
59c97189	327	authenticated = 0;
3c418020	328	#endif
2b87da3b	329	#ifdef USE_PAM
94ec8c6b	330	if (authenticated && !do_pam_account(pw->pw_name, client_user))
	331	authenticated = 0;
	332	#endif
a306f2dd	333
59c97189	334	/* Log before sending the reply */
	335	auth_log(authctxt, authenticated, get_authname(type), info);
	336
a306f2dd	337	if (client_user != NULL) {
	338	xfree(client_user);
	339	client_user = NULL;
	340	}
	341
94ec8c6b	342	if (authenticated)
	343	return;
	344
b4b5d644	345	if (authctxt->failures++ > AUTH_FAIL_MAX) {
2b87da3b	346	#ifdef WITH_AIXAUTHENTICATE
	347	loginfailed(authctxt->user,
	348	get_canonical_hostname(options.reverse_mapping_check),
61e96248	349	"ssh");
c1ef8333	350	#endif /* WITH_AIXAUTHENTICATE */
59c97189	351	packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
c1ef8333	352	}
a306f2dd	353
a306f2dd	354	packet_start(SSH_SMSG_FAILURE);
	355	packet_send();
	356	packet_write_wait();
	357	}
	358	}
	359
	360	/*
	361	* Performs authentication of an incoming connection. Session key has already
	362	* been exchanged and encryption is enabled.
	363	*/
	364	void
d5bb9418	365	do_authentication(void)
a306f2dd	366	{
59c97189	367	Authctxt *authctxt;
59c97189	368	struct passwd *pw;
a306f2dd	369	int plen;
1e3b8b07	370	u_int ulen;
ced49be2	371	char p, user, *style = NULL;
a306f2dd	372
	373	/* Get the name of the user that we wish to log in as. */
	374	packet_read_expect(&plen, SSH_CMSG_USER);
	375
	376	/* Get the user name. */
	377	user = packet_get_string(&ulen);
	378	packet_integrity_check(plen, (4 + ulen), SSH_CMSG_USER);
	379
59c97189	380	if ((style = strchr(user, ':')) != NULL)
ced49be2	381	*style++ = '\0';
59c97189	382
ced49be2	383	/* XXX - SSH.com Kerberos v5 braindeath. */
	384	if ((p = strchr(user, '@')) != NULL)
	385	*p = '\0';
184eed6a	386
59c97189	387	authctxt = authctxt_new();
	388	authctxt->user = user;
	389	authctxt->style = style;
	390
a306f2dd	391	/* Verify that the user is a valid user. */
a306f2dd	392	pw = getpwnam(user);
94ec8c6b	393	if (pw && allowed_user(pw)) {
59c97189	394	authctxt->valid = 1;
59c97189	395	pw = pwcopy(pw);
94ec8c6b	396	} else {
59c97189	397	debug("do_authentication: illegal user %s", user);
94ec8c6b	398	pw = NULL;
94ec8c6b	399	}
59c97189	400	authctxt->pw = pw;
a306f2dd	401
6172e290	402	setproctitle("%s", pw ? user : "unknown");
6172e290	403
a306f2dd	404	#ifdef USE_PAM
94ec8c6b	405	if (pw)
04fc7a67	406	start_pam(user);
a306f2dd	407	#endif
	408
	409	/*
	410	* If we are not running as root, the user must have the same uid as
94ec8c6b	411	* the server. (Unless you are running Windows)
a306f2dd	412	*/
94ec8c6b	413	#ifndef HAVE_CYGWIN
94ec8c6b	414	if (getuid() != 0 && pw && pw->pw_uid != getuid())
a306f2dd	415	packet_disconnect("Cannot change user when server not running as root.");
3c62e7eb	416	#endif
a306f2dd	417
59c97189	418	/*
b4b5d644	419	* Loop until the user has been authenticated or the connection is
	420	* closed, do_authloop() returns only if authentication is successful
	421	*/
59c97189	422	do_authloop(authctxt);
a306f2dd	423
a306f2dd	424	/* The user has been authenticated and accepted. */
94ec8c6b	425	packet_start(SSH_SMSG_SUCCESS);
	426	packet_send();
	427	packet_write_wait();
59c97189	428
a306f2dd	429	/* Perform session preparation. */
bb5639fe	430	do_authenticated(authctxt);
a306f2dd	431	}