Esempio n. 1
0
int
mm_auth_rsa_key_allowed(struct passwd *pw, BIGNUM *client_n, Key **rkey)
{
	Buffer m;
	Key *key;
	u_char *blob;
	u_int blen;
	int allowed = 0, have_forced = 0;

	debug3("%s entering", __func__);

	buffer_init(&m);
	buffer_put_bignum2(&m, client_n);

	mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_RSAKEYALLOWED, &m);
	mm_request_receive_expect(pmonitor->m_recvfd, MONITOR_ANS_RSAKEYALLOWED, &m);

	allowed = buffer_get_int(&m);

	/* fake forced command */
	auth_clear_options();
	have_forced = buffer_get_int(&m);
	forced_command = have_forced ? xstrdup("true") : NULL;

	if (allowed && rkey != NULL) {
		blob = buffer_get_string(&m, &blen);
		if ((key = key_from_blob(blob, blen)) == NULL)
			fatal("%s: key_from_blob failed", __func__);
		*rkey = key;
		xfree(blob);
	}
	buffer_free(&m);

	return (allowed);
}
Esempio n. 2
0
int
mm_answer_rsa_challenge(int sock, Buffer *m)
{
	Key *key = NULL;
	u_char *blob;
	u_int blen;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch", __func__);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);

	if (ssh1_challenge)
		BN_clear_free(ssh1_challenge);
	ssh1_challenge = auth_rsa_generate_challenge(key);

	buffer_clear(m);
	buffer_put_bignum2(m, ssh1_challenge);

	debug3("%s sending reply", __func__);
	mm_request_send(sock, MONITOR_ANS_RSACHALLENGE, m);

	monitor_permit(mon_dispatch, MONITOR_REQ_RSARESPONSE, 1);

	xfree(blob);
	key_free(key);
	return (0);
}
Esempio n. 3
0
int
mm_answer_keyverify(int sock, Buffer *m)
{
	Key *key;
	u_char *signature, *data, *blob;
	u_int signaturelen, datalen, bloblen;
	int verified = 0;
	int valid_data = 0;

	blob = buffer_get_string(m, &bloblen);
	signature = buffer_get_string(m, &signaturelen);
	data = buffer_get_string(m, &datalen);

	if (hostbased_cuser == NULL || hostbased_chost == NULL ||
	  !monitor_allowed_key(blob, bloblen))
		fatal("%s: bad key, not previously allowed", __func__);

	key = key_from_blob(blob, bloblen);
	if (key == NULL)
		fatal("%s: bad public key blob", __func__);

	switch (key_blobtype) {
	case MM_USERKEY:
		valid_data = monitor_valid_userblob(data, datalen);
		break;
	case MM_HOSTKEY:
		valid_data = monitor_valid_hostbasedblob(data, datalen,
		    hostbased_cuser, hostbased_chost);
		break;
	default:
		valid_data = 0;
		break;
	}
	if (!valid_data)
		fatal("%s: bad signature data blob", __func__);

	verified = key_verify(key, signature, signaturelen, data, datalen);
	debug3("%s: key %p signature %s",
	    __func__, key, (verified == 1) ? "verified" : "unverified");

	/* If auth was successful then record key to ensure it isn't reused */
	if (verified == 1 && key_blobtype == MM_USERKEY)
		auth2_record_userkey(authctxt, key);
	else
		key_free(key);

	free(blob);
	free(signature);
	free(data);

	auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased";

	monitor_reset_key_state();

	buffer_clear(m);
	buffer_put_int(m, verified);
	mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);

	return (verified == 1);
}
Esempio n. 4
0
Key *
ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
{
#ifdef WITH_SSH1
	int keybits;
	u_int bits;
#endif
	u_char *blob;
	u_int blen;
	Key *key = NULL;

	/* Return failure if no more entries. */
	if (auth->howmany <= 0)
		return NULL;

	/*
	 * Get the next entry from the packet.  These will abort with a fatal
	 * error if the packet is too short or contains corrupt data.
	 */
	switch (version) {
#ifdef WITH_SSH1
	case 1:
		key = key_new(KEY_RSA1);
		bits = buffer_get_int(&auth->identities);
		buffer_get_bignum(&auth->identities, key->rsa->e);
		buffer_get_bignum(&auth->identities, key->rsa->n);
		*comment = buffer_get_string(&auth->identities, NULL);
		keybits = BN_num_bits(key->rsa->n);
		if (keybits < 0 || bits != (u_int)keybits)
			logit("Warning: identity keysize mismatch: actual %d, announced %u",
			    BN_num_bits(key->rsa->n), bits);
		break;
#endif
	case 2:
		blob = buffer_get_string(&auth->identities, &blen);
		*comment = buffer_get_string(&auth->identities, NULL);
		key = key_from_blob(blob, blen);
		free(blob);
		break;
	default:
		return NULL;
	}
	/* Decrement the number of remaining entries. */
	auth->howmany--;
	return key;
}
Esempio n. 5
0
int
mm_answer_rsa_response(int sock, Buffer *m)
{
	Key *key = NULL;
	u_char *blob, *response;
	u_int blen, len;
	int success;

	debug3("%s entering", __func__);

	if (!authctxt->valid)
		fatal("%s: authctxt not valid", __func__);
	if (ssh1_challenge == NULL)
		fatal("%s: no ssh1_challenge", __func__);

	blob = buffer_get_string(m, &blen);
	if (!monitor_allowed_key(blob, blen))
		fatal("%s: bad key, not previously allowed", __func__);
	if (key_blobtype != MM_RSAUSERKEY && key_blobtype != MM_RSAHOSTKEY)
		fatal("%s: key type mismatch: %d", __func__, key_blobtype);
	if ((key = key_from_blob(blob, blen)) == NULL)
		fatal("%s: received bad key", __func__);
	response = buffer_get_string(m, &len);
	if (len != 16)
		fatal("%s: received bad response to challenge", __func__);
	success = auth_rsa_verify_response(key, ssh1_challenge, response);

	xfree(blob);
	key_free(key);
	xfree(response);

	auth_method = key_blobtype == MM_RSAUSERKEY ? "rsa" : "rhosts-rsa";

	/* reset state */
	BN_clear_free(ssh1_challenge);
	ssh1_challenge = NULL;
	monitor_reset_key_state();

	buffer_clear(m);
	buffer_put_int(m, success);
	mm_request_send(sock, MONITOR_ANS_RSARESPONSE, m);

	return (success);
}
Esempio n. 6
0
int
pkcs11_add_provider(char *name, char *pin, Key ***keysp)
{
	Key *k;
	int i, nkeys;
	u_char *blob;
	u_int blen;
	Buffer msg;

	if (fd < 0 && pkcs11_start_helper() < 0)
		return (-1);

	buffer_init(&msg);
	buffer_put_char(&msg, SSH_AGENTC_ADD_SMARTCARD_KEY);
	buffer_put_cstring(&msg, name);
	buffer_put_cstring(&msg, pin);
	send_msg(&msg);
	buffer_clear(&msg);

	if (recv_msg(&msg) == SSH2_AGENT_IDENTITIES_ANSWER) {
		nkeys = buffer_get_int(&msg);
		*keysp = xcalloc(nkeys, sizeof(Key *));
		for (i = 0; i < nkeys; i++) {
			blob = buffer_get_string(&msg, &blen);
			free(buffer_get_string(&msg, NULL));
			k = key_from_blob(blob, blen);
			wrap_key(k->rsa);
			(*keysp)[i] = k;
			free(blob);
		}
	} else {
		nkeys = -1;
	}
	buffer_free(&msg);
	return (nkeys);
}
Esempio n. 7
0
static int
userauth_pubkey(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_pubkey: disabled because of invalid user");
		return 0;
	}
	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		logit("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&b, authctxt->user);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		/* test for correct signature */
		authenticated = 0;
		if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b))) == 1)
			authenticated = 1;
		buffer_free(&b);
		xfree(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->postponed = 1;
		}
	}
	if (authenticated != 1)
		auth_clear_options();
done:
	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
	return authenticated;
}
Esempio n. 8
0
static int
valid_request(struct passwd *pw, char *host, Key **ret, u_char *data,
    u_int datalen)
{
	Buffer b;
	Key *key = NULL;
	u_char *pkblob;
	u_int blen, len;
	char *pkalg, *p;
	int pktype, fail;

	fail = 0;

	buffer_init(&b);
	buffer_append(&b, data, datalen);

	/* session id, currently limited to SHA1 (20 bytes) or SHA256 (32) */
	p = buffer_get_string(&b, &len);
	if (len != 20 && len != 32)
		fail++;
	xfree(p);

	if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST)
		fail++;

	/* server user */
	buffer_skip_string(&b);

	/* service */
	p = buffer_get_string(&b, NULL);
	if (strcmp("ssh-connection", p) != 0)
		fail++;
	xfree(p);

	/* method */
	p = buffer_get_string(&b, NULL);
	if (strcmp("hostbased", p) != 0)
		fail++;
	xfree(p);

	/* pubkey */
	pkalg = buffer_get_string(&b, NULL);
	pkblob = buffer_get_string(&b, &blen);

	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC)
		fail++;
	else if ((key = key_from_blob(pkblob, blen)) == NULL)
		fail++;
	else if (key->type != pktype)
		fail++;
	xfree(pkalg);
	xfree(pkblob);

	/* client host name, handle trailing dot */
	p = buffer_get_string(&b, &len);
	debug2("valid_request: check expect chost %s got %s", host, p);
	if (strlen(host) != len - 1)
		fail++;
	else if (p[len - 1] != '.')
		fail++;
	else if (strncasecmp(host, p, len - 1) != 0)
		fail++;
	xfree(p);

	/* local user */
	p = buffer_get_string(&b, NULL);

	if (strcmp(pw->pw_name, p) != 0)
		fail++;
	xfree(p);

	/* end of message */
	if (buffer_len(&b) != 0)
		fail++;
	buffer_free(&b);

	debug3("valid_request: fail %d", fail);

	if (fail && key != NULL)
		key_free(key);
	else
		*ret = key;

	return (fail ? -1 : 0);
}
Esempio n. 9
0
int
mm_answer_keyallowed(int sock, Buffer *m)
{
	struct sshkey *key;
	char *cuser, *chost;
	u_char *blob;
	u_int bloblen, pubkey_auth_attempt;
	enum mm_keytype type = 0;
	int allowed = 0;

	debug3("%s entering", __func__);

	type = buffer_get_int(m);
	cuser = buffer_get_string(m, NULL);
	chost = buffer_get_string(m, NULL);
	blob = buffer_get_string(m, &bloblen);
	pubkey_auth_attempt = buffer_get_int(m);

	key = key_from_blob(blob, bloblen);

	debug3("%s: key_from_blob: %p", __func__, key);

	if (key != NULL && authctxt->valid) {
		/* These should not make it past the privsep child */
		if (key_type_plain(key->type) == KEY_RSA &&
		    (datafellows & SSH_BUG_RSASIGMD5) != 0)
			fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__);

		switch (type) {
		case MM_USERKEY:
			allowed = options.pubkey_authentication &&
			    !auth2_key_already_used(authctxt, key) &&
			    match_pattern_list(sshkey_ssh_name(key),
			    options.pubkey_key_types, 0) == 1 &&
			    user_key_allowed(authctxt->pw, key,
			    pubkey_auth_attempt);
			auth_method = "publickey";
			if (options.pubkey_authentication &&
			    (!pubkey_auth_attempt || allowed != 1))
				auth_clear_options();
			break;
		case MM_HOSTKEY:
			allowed = options.hostbased_authentication &&
			    !auth2_key_already_used(authctxt, key) &&
			    match_pattern_list(sshkey_ssh_name(key),
			    options.hostbased_key_types, 0) == 1 &&
			    hostbased_key_allowed(authctxt->pw,
			    cuser, chost, key);
			auth2_record_info(authctxt,
			    "client user \"%.100s\", client host \"%.100s\"",
			    cuser, chost);
			auth_method = "hostbased";
			break;
		default:
			fatal("%s: unknown key type %d", __func__, type);
			break;
		}
	}

	debug3("%s: key is %s", __func__, allowed ? "allowed" : "not allowed");

	auth2_record_key(authctxt, 0, key);
	sshkey_free(key);

	/* clear temporarily storage (used by verify) */
	monitor_reset_key_state();

	if (allowed) {
		/* Save temporarily for comparison in verify */
		key_blob = blob;
		key_bloblen = bloblen;
		key_blobtype = type;
		hostbased_cuser = cuser;
		hostbased_chost = chost;
	} else {
		/* Log failed attempt */
		auth_log(authctxt, 0, 0, auth_method, NULL);
		free(blob);
		free(cuser);
		free(chost);
	}

	buffer_clear(m);
	buffer_put_int(m, allowed);
	buffer_put_int(m, forced_command != NULL);

	mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);

	return (0);
}
Esempio n. 10
0
void
kexecdh_client(Kex *kex)
{
	EC_KEY *client_key;
	EC_POINT *server_public;
	const EC_GROUP *group;
	BIGNUM *shared_secret;
	Key *server_host_key;
	u_char *server_host_key_blob = NULL, *signature = NULL;
	u_char *kbuf, *hash;
	u_int klen, slen, sbloblen, hashlen;

	if ((client_key = EC_KEY_new_by_curve_name(kex->ec_nid)) == NULL)
		fatal("%s: EC_KEY_new_by_curve_name failed", __func__);
	if (EC_KEY_generate_key(client_key) != 1)
		fatal("%s: EC_KEY_generate_key failed", __func__);
	group = EC_KEY_get0_group(client_key);

	packet_start(SSH2_MSG_KEX_ECDH_INIT);
	packet_put_ecpoint(group, EC_KEY_get0_public_key(client_key));
	packet_send();
	debug("sending SSH2_MSG_KEX_ECDH_INIT");

#ifdef DEBUG_KEXECDH
	fputs("client private key:\n", stderr);
	key_dump_ec_key(client_key);
#endif

	debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
	packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);

	/* hostkey */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");
	if (server_host_key->type != kex->hostkey_type)
		fatal("type mismatch for decoded server_host_key_blob");
	if (kex->verify_host_key == NULL)
		fatal("cannot verify server_host_key");
	if (kex->verify_host_key(server_host_key) == -1)
		fatal("server_host_key verification failed");

	/* Q_S, server public key */
	if ((server_public = EC_POINT_new(group)) == NULL)
		fatal("%s: EC_POINT_new failed", __func__);
	packet_get_ecpoint(group, server_public);

	if (key_ec_validate_public(group, server_public) != 0)
		fatal("%s: invalid server public key", __func__);

#ifdef DEBUG_KEXECDH
	fputs("server public key:\n", stderr);
	key_dump_ec_point(group, server_public);
#endif

	/* signed H */
	signature = packet_get_string(&slen);
	packet_check_eom();

	klen = (EC_GROUP_get_degree(group) + 7) / 8;
	kbuf = xmalloc(klen);
	if (ECDH_compute_key(kbuf, klen, server_public,
	    client_key, NULL) != (int)klen)
		fatal("%s: ECDH_compute_key failed", __func__);

#ifdef DEBUG_KEXECDH
	dump_digest("shared secret", kbuf, klen);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("%s: BN_new failed", __func__);
	if (BN_bin2bn(kbuf, klen, shared_secret) == NULL)
		fatal("%s: BN_bin2bn failed", __func__);
	memset(kbuf, 0, klen);
	free(kbuf);

	/* calc and verify H */
	kex_ecdh_hash(
	    kex->evp_md,
	    group,
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    server_host_key_blob, sbloblen,
	    EC_KEY_get0_public_key(client_key),
	    server_public,
	    shared_secret,
	    &hash, &hashlen
	);
	free(server_host_key_blob);
	EC_POINT_clear_free(server_public);
	EC_KEY_free(client_key);

	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
		fatal("key_verify failed for server_host_key");
	key_free(server_host_key);
	free(signature);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}
Esempio n. 11
0
static int
userauth_pubkey(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg, *userstyle;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_pubkey: disabled because of invalid user");
		return 0;
	}
	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		logit("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	if (key_type_plain(key->type) == KEY_RSA &&
	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
		logit("Refusing RSA key because client uses unsafe "
		    "signature scheme");
		goto done;
	}
	if (auth2_userkey_already_used(authctxt, key)) {
		logit("refusing previously-used %s key", key_type(key));
		goto done;
	}
	if (match_pattern_list(sshkey_ssh_name(key), options.pubkey_key_types,
	    strlen(options.pubkey_key_types), 0) != 1) {
		logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
		    __func__, sshkey_ssh_name(key));
		goto done;
	}

	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		xasprintf(&userstyle, "%s%s%s", authctxt->user,
		    authctxt->style ? ":" : "",
		    authctxt->style ? authctxt->style : "");
		buffer_put_cstring(&b, userstyle);
		free(userstyle);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		pubkey_auth_info(authctxt, key, NULL);

		/* test for correct signature */
		authenticated = 0;
		if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b))) == 1) {
			authenticated = 1;
			/* Record the successful key to prevent reuse */
			auth2_record_userkey(authctxt, key);
			key = NULL; /* Don't free below */
		}
		buffer_free(&b);
		free(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->postponed = 1;
		}
	}
	if (authenticated != 1)
		auth_clear_options();
done:
	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	free(pkalg);
	free(pkblob);
	return authenticated;
}
Esempio n. 12
0
static int
userauth_pubkey(Authctxt *authctxt)
{
  #ifdef WIN32_FIXME
  
  int loginStat = 1;

  char currentUser[MAX_PATH] = {0};
  
  DWORD currentUserSize = sizeof(currentUser);
  
  int targetIsCurrent = 0;

  # ifdef USE_NTCREATETOKEN
  int doOpenSSHVerify = 1;
  # else
  int doOpenSSHVerify = 0;
  # endif

  #endif
  
	Buffer b;
	Key *key = NULL;
	char *pkalg, *userstyle;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_pubkey: disabled because of invalid user");
		return 0;
	}
	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		logit("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	if (key_type_plain(key->type) == KEY_RSA &&
	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
		logit("Refusing RSA key because client uses unsafe "
		    "signature scheme");
		goto done;
	}
	if (auth2_userkey_already_used(authctxt, key)) {
		logit("refusing previously-used %s key", key_type(key));
		goto done;
	}
	if (match_pattern_list(sshkey_ssh_name(key),
	    options.pubkey_key_types, 0) != 1) {
		logit("%s: key type %s not in PubkeyAcceptedKeyTypes",
		    __func__, sshkey_ssh_name(key));
		goto done;
	}

	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		xasprintf(&userstyle, "%s%s%s", authctxt->user,
		    authctxt->style ? ":" : "",
		    authctxt->style ? authctxt->style : "");
		buffer_put_cstring(&b, userstyle);
		free(userstyle);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		pubkey_auth_info(authctxt, key, NULL);

		/* test for correct signature */
		authenticated = 0;
   /*
     * On pure win32 try to logon using lsa first.
     */

    #ifdef WIN32_FIXME

    authctxt -> hTokenLsa_ = NULL;
    authctxt -> methoddata = NULL;
 
    /*
     * Retrieve name of current login user (i.e. sshd process owner).
     */
     
    GetUserName(currentUser, &currentUserSize);

    /*
     * Try to get token from lsa, but only if targetUser != currentUser.
     * Owerthise we already have targetUser's token in current thread, so
     * we only need key verify from original OpenSSH code.
     */

    targetIsCurrent = (strcmp(currentUser, authctxt -> user) == 0);
    
    if (targetIsCurrent)
    {
      doOpenSSHVerify = 1;
    }
    else
    {
      loginStat = LsaLogon(&authctxt -> hTokenLsa_, HomeDirLsaW,
                               authctxt -> user, pkblob, blen, sig, slen,
                                 buffer_ptr(&b), buffer_len(&b), datafellows);

      /*
       * If lsa logon process success.
       */
  
      if (loginStat == 0)
      {
        /*
         * And user authorized OK.
         */
    
        if (authctxt -> hTokenLsa_)
        {
          doOpenSSHVerify = 0;
          
          /*
           * This is part of openssh authorization needed for parsing
           * 'options' block in key.
           */
      
          authctxt -> pw -> pw_dir = GetHomeDir(authctxt -> user);
      
          if (PRIVSEP(user_key_allowed(authctxt -> pw, key, 1))) // PRAGMA:TODO
          {
            authenticated = 1;
          }
          else
          {
            authenticated = 0;
          }
          
          buffer_free(&b);

          free(sig);
        }
      }
    }
    
    if (doOpenSSHVerify)
    {
      /*
       * If lsa fails, test for correct signature using openssh code.
       */
      
      authctxt -> pw -> pw_dir = GetHomeDir(authctxt -> user);
  
      if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0))  //PRAGMA:TODO
		  &&
              PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b))) == 1)
    
      {
        authenticated = 1;
      }
    }
    
    /*
     * Original code.
     */

    #else /* #ifdef WIN32_FIXME */

		if (PRIVSEP(user_key_allowed(authctxt->pw, key, 1)) &&
		    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b))) == 1) {
			authenticated = 1;
			/* Record the successful key to prevent reuse */
			auth2_record_userkey(authctxt, key);
			key = NULL; /* Don't free below */
		}
		buffer_free(&b);
		free(sig);
   #endif /* else #ifdef WIN32_FIXME. */

	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		

      #ifndef WIN32_FIXME

     if (PRIVSEP(user_key_allowed(authctxt->pw, key, 0)))  
 
      #endif		
		{
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->postponed = 1;
		}
	}
	if (authenticated != 1)
		auth_clear_options();
done:
	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	free(pkalg);
	free(pkblob);
	return authenticated;
}
Esempio n. 13
0
void
input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Key *key = NULL;
	Buffer b;
	int pktype, sent = 0;
	u_int alen, blen;
	char *pkalg, *fp;
	u_char *pkblob;

	if (authctxt == NULL)
		fatal("input_userauth_pk_ok: no authentication context");
	if (datafellows & SSH_BUG_PKOK) {
		/* this is similar to SSH_BUG_PKAUTH */
		debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	packet_check_eom();

	debug("Server accepts key: pkalg %s blen %u lastkey %p hint %d",
	    pkalg, blen, authctxt->last_key, authctxt->last_key_hint);

	do {
		if (authctxt->last_key == NULL ||
		    authctxt->last_key_sign == NULL) {
			debug("no last key or no sign cb");
			break;
		}
		if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
			debug("unknown pkalg %s", pkalg);
			break;
		}
		if ((key = key_from_blob(pkblob, blen)) == NULL) {
			debug("no key from blob. pkalg %s", pkalg);
			break;
		}
		if (key->type != pktype) {
			error("input_userauth_pk_ok: type mismatch "
			    "for decoded key (received %d, expected %d)",
			    key->type, pktype);
			break;
		}
		fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
		debug2("input_userauth_pk_ok: fp %s", fp);
		xfree(fp);
		if (!key_equal(key, authctxt->last_key)) {
			debug("key != last_key");
			break;
		}
		sent = sign_and_send_pubkey(authctxt, key,
		   authctxt->last_key_sign);
	} while (0);

	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);

	/* unregister */
	clear_auth_state(authctxt);
	dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL);

	/* try another method if we did not send a packet */
	if (sent == 0)
		userauth(authctxt, NULL);

}
Esempio n. 14
0
void
kexgex_client(Kex *kex)
{
	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
	BIGNUM *p = NULL, *g = NULL;
	Key *server_host_key;
	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
	u_int klen, slen, sbloblen, hashlen;
	int kout;
	int min, max, nbits;
	DH *dh;

	nbits = dh_estimate(kex->dh_need * 8);

	if (datafellows & SSH_OLD_DHGEX) {
		/* Old GEX request */
		packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
		packet_put_int(nbits);
		min = DH_GRP_MIN;
		max = DH_GRP_MAX;

		debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
	} else {
		/* New GEX request */
		min = DH_GRP_MIN;
		max = DH_GRP_MAX;
		packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
		packet_put_int(min);
		packet_put_int(nbits);
		packet_put_int(max);

		debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
		    min, nbits, max);
	}
#ifdef DEBUG_KEXDH
	fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
	    min, nbits, max);
#endif
	packet_send();

	debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
	packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);

	if ((p = BN_new()) == NULL)
		fatal("BN_new");
	packet_get_bignum2(p);
	if ((g = BN_new()) == NULL)
		fatal("BN_new");
	packet_get_bignum2(g);
	packet_check_eom();

	if (BN_num_bits(p) < min || BN_num_bits(p) > max)
		fatal("DH_GEX group out of range: %d !< %d !< %d",
		    min, BN_num_bits(p), max);

	dh = dh_new_group(g, p);
	dh_gen_key(dh, kex->we_need * 8);

#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif

	debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
	/* generate and send 'e', client DH public key */
	packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
	packet_put_bignum2(dh->pub_key);
	packet_send();

	debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
	packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);

	/* key, cert */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");
	if (server_host_key->type != kex->hostkey_type)
		fatal("type mismatch for decoded server_host_key_blob");
	if (kex->verify_host_key == NULL)
		fatal("cannot verify server_host_key");
	if (kex->verify_host_key(server_host_key) == -1)
		fatal("server_host_key verification failed");

	/* DH parameter f, server public DH key */
	if ((dh_server_pub = BN_new()) == NULL)
		fatal("dh_server_pub == NULL");
	packet_get_bignum2(dh_server_pub);

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_server_pub= ");
	BN_print_fp(stderr, dh_server_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_server_pub));
#endif

	/* signed H */
	signature = packet_get_string(&slen);
	packet_check_eom();

	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
		fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexgex_client: BN_new failed");
	if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
		fatal("kexgex_client: BN_bin2bn failed");
	explicit_bzero(kbuf, klen);
	free(kbuf);

	if (datafellows & SSH_OLD_DHGEX)
		min = max = -1;

	/* calc and verify H */
	kexgex_hash(
	    kex->hash_alg,
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    server_host_key_blob, sbloblen,
	    min, nbits, max,
	    dh->p, dh->g,
	    dh->pub_key,
	    dh_server_pub,
	    shared_secret,
	    &hash, &hashlen
	);

	/* have keys, free DH */
	DH_free(dh);
	free(server_host_key_blob);
	BN_clear_free(dh_server_pub);

	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
		fatal("key_verify failed for server_host_key");
	key_free(server_host_key);
	free(signature);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}
	kex_derive_keys_bn(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);

	kex_finish(kex);
}
Esempio n. 15
0
static void
userauth_pubkey(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int have_sig, pktype;
	int authenticated = 0;

	if (!authctxt || !authctxt->method)
		fatal("%s: missing context", __func__);

	have_sig = packet_get_char();
	if (datafellows & SSH_BUG_PKAUTH) {
		debug2("userauth_pubkey: SSH_BUG_PKAUTH");
		/* no explicit pkalg given */
		pkblob = packet_get_string(&blen);
		buffer_init(&b);
		buffer_append(&b, pkblob, blen);
		/* so we have to extract the pkalg from the pkblob */
		pkalg = buffer_get_string(&b, &alen);
		buffer_free(&b);
	} else {
		pkalg = packet_get_string(&alen);
		pkblob = packet_get_string(&blen);
	}
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		log("userauth_pubkey: unsupported public key algorithm: %s",
		    pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_pubkey: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_pubkey: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}

	/* Detect and count abandonment */
	if (authctxt->method->method_data) {
		Key	*prev_key;
		unsigned char	*prev_pkblob;
		int	 prev_blen;

		/*
		 * Check for earlier test of a key that was allowed but
		 * not followed up with a pubkey req for the same pubkey
		 * and with a signature.
		 */
		prev_key = authctxt->method->method_data;
		if ((prev_blen = key_to_blob(prev_key,
			    &prev_pkblob, NULL))) {
			if (prev_blen != blen ||
			    memcmp(prev_pkblob, pkblob, blen) != 0) {
				authctxt->method->abandons++;
				authctxt->method->attempts++;
			}
		}
		key_free(prev_key);
		authctxt->method->method_data = NULL;
	}

	if (have_sig) {
		sig = packet_get_string(&slen);
		packet_check_eom();
		buffer_init(&b);
		if (datafellows & SSH_OLD_SESSIONID) {
			buffer_append(&b, session_id2, session_id2_len);
		} else {
			buffer_put_string(&b, session_id2, session_id2_len);
		}
		/* reconstruct packet */
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&b, authctxt->user);
		buffer_put_cstring(&b,
		    datafellows & SSH_BUG_PKSERVICE ?
		    "ssh-userauth" :
		    authctxt->service);
		if (datafellows & SSH_BUG_PKAUTH) {
			buffer_put_char(&b, have_sig);
		} else {
			buffer_put_cstring(&b, "publickey");
			buffer_put_char(&b, have_sig);
			buffer_put_cstring(&b, pkalg);
		}
		buffer_put_string(&b, pkblob, blen);
#ifdef DEBUG_PK
		buffer_dump(&b);
#endif
		/* test for correct signature */
		if (user_key_allowed(authctxt->pw, key) &&
		    key_verify(key, sig, slen, buffer_ptr(&b),
		    buffer_len(&b)) == 1) {
			authenticated = 1;
		}
		authctxt->method->postponed = 0;
		buffer_free(&b);
		xfree(sig);
	} else {
		debug("test whether pkalg/pkblob are acceptable");
		packet_check_eom();

		/* XXX fake reply and always send PK_OK ? */
		/*
		 * XXX this allows testing whether a user is allowed
		 * to login: if you happen to have a valid pubkey this
		 * message is sent. the message is NEVER sent at all
		 * if a user is not allowed to login. is this an
		 * issue? -markus
		 */
		if (user_key_allowed(authctxt->pw, key)) {
			packet_start(SSH2_MSG_USERAUTH_PK_OK);
			packet_put_string(pkalg, alen);
			packet_put_string(pkblob, blen);
			packet_send();
			packet_write_wait();
			authctxt->method->postponed = 1;
			/*
			 * Remember key that was tried so we can
			 * correctly detect abandonment.  See above.
			 */
			authctxt->method->method_data = (void *) key;
			key = NULL;
		}
	}
	if (authenticated != 1)
		auth_clear_options();

done:
	/*
	 * XXX TODO: add config options for specifying users for whom
	 * this userauth is insufficient and what userauths may
	 * continue.
	 */
#ifdef USE_PAM
	if (authenticated) {
		if (!do_pam_non_initial_userauth(authctxt))
			authenticated = 0;
	}
#endif /* USE_PAM */

	debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
#ifdef HAVE_CYGWIN
	if (check_nt_auth(0, authctxt->pw) == 0)
		return;
#endif
	if (authenticated)
		authctxt->method->authenticated = 1;
}
Esempio n. 16
0
int
mm_answer_keyallowed(int sock, Buffer *m)
{
	Key *key;
	char *cuser, *chost;
	u_char *blob;
	u_int bloblen;
	enum mm_keytype type = 0;
	int allowed = 0;

	debug3("%s entering", __func__);

	type = buffer_get_int(m);
	cuser = buffer_get_string(m, NULL);
	chost = buffer_get_string(m, NULL);
	blob = buffer_get_string(m, &bloblen);

	key = key_from_blob(blob, bloblen);

	if ((compat20 && type == MM_RSAHOSTKEY) ||
	    (!compat20 && type != MM_RSAHOSTKEY))
		fatal("%s: key type and protocol mismatch", __func__);

	debug3("%s: key_from_blob: %p", __func__, key);

	if (key != NULL && authctxt->valid) {
		switch (type) {
		case MM_USERKEY:
			allowed = options.pubkey_authentication &&
			    user_key_allowed(authctxt->pw, key);
			break;
		case MM_HOSTKEY:
			allowed = options.hostbased_authentication &&
			    hostbased_key_allowed(authctxt->pw,
			    cuser, chost, key);
			break;
		case MM_RSAHOSTKEY:
			key->type = KEY_RSA1; /* XXX */
			allowed = options.rhosts_rsa_authentication &&
			    auth_rhosts_rsa_key_allowed(authctxt->pw,
			    cuser, chost, key);
			break;
		default:
			fatal("%s: unknown key type %d", __func__, type);
			break;
		}
	}
	if (key != NULL)
		key_free(key);

	/* clear temporarily storage (used by verify) */
	monitor_reset_key_state();

	if (allowed) {
		/* Save temporarily for comparison in verify */
		key_blob = blob;
		key_bloblen = bloblen;
		key_blobtype = type;
		hostbased_cuser = cuser;
		hostbased_chost = chost;
	}

	debug3("%s: key %p is %s",
	    __func__, key, allowed ? "allowed" : "disallowed");

	buffer_clear(m);
	buffer_put_int(m, allowed);
	buffer_put_int(m, forced_command != NULL);

	mm_append_debug(m);

	mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);

	if (type == MM_RSAHOSTKEY)
		monitor_permit(mon_dispatch, MONITOR_REQ_RSACHALLENGE, allowed);

	return (0);
}
Esempio n. 17
0
void
kexdh_client(Kex *kex)
{
	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
	DH *dh;
	Key *server_host_key;
	u_char *server_host_key_blob = NULL, *signature = NULL;
	u_char *kbuf, *hash;
	u_int klen, slen, sbloblen, hashlen;
	int kout;

	/* generate and send 'e', client DH public key */
	switch (kex->kex_type) {
	case KEX_DH_GRP1_SHA1:
		dh = dh_new_group1();
		break;
	case KEX_DH_GRP14_SHA1:
		dh = dh_new_group14();
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}
	dh_gen_key(dh, kex->we_need * 8);
	packet_start(SSH2_MSG_KEXDH_INIT);
	packet_put_bignum2(dh->pub_key);
	packet_send();

	debug("sending SSH2_MSG_KEXDH_INIT");
#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif

	debug("expecting SSH2_MSG_KEXDH_REPLY");
	packet_read_expect(SSH2_MSG_KEXDH_REPLY);

	/* key, cert */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");
	if (server_host_key->type != kex->hostkey_type)
		fatal("type mismatch for decoded server_host_key_blob");
	if (kex->verify_host_key == NULL)
		fatal("cannot verify server_host_key");
	if (kex->verify_host_key(server_host_key) == -1)
		fatal("server_host_key verification failed");

	/* DH parameter f, server public DH key */
	if ((dh_server_pub = BN_new()) == NULL)
		fatal("dh_server_pub == NULL");
	packet_get_bignum2(dh_server_pub);

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_server_pub= ");
	BN_print_fp(stderr, dh_server_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_server_pub));
#endif

	/* signed H */
	signature = packet_get_string(&slen);
	packet_check_eom();

	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	if ((kout = DH_compute_key(kbuf, dh_server_pub, dh)) < 0)
		fatal("DH_compute_key: failed");
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexdh_client: BN_new failed");
	if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
		fatal("kexdh_client: BN_bin2bn failed");
	memset(kbuf, 0, klen);
	free(kbuf);

	/* calc and verify H */
	kex_dh_hash(
	    kex->client_version_string,
	    kex->server_version_string,
	    buffer_ptr(&kex->my), buffer_len(&kex->my),
	    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	    server_host_key_blob, sbloblen,
	    dh->pub_key,
	    dh_server_pub,
	    shared_secret,
	    &hash, &hashlen
	);
	free(server_host_key_blob);
	BN_clear_free(dh_server_pub);
	DH_free(dh);

	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
		fatal("key_verify failed for server_host_key");
	key_free(server_host_key);
	free(signature);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}
Esempio n. 18
0
static int
userauth_hostbased(Authctxt *authctxt)
{
	Buffer b;
	Key *key = NULL;
	char *pkalg, *cuser, *chost, *service;
	u_char *pkblob, *sig;
	u_int alen, blen, slen;
	int pktype;
	int authenticated = 0;

	if (!authctxt->valid) {
		debug2("userauth_hostbased: disabled because of invalid user");
		return 0;
	}
	pkalg = packet_get_string(&alen);
	pkblob = packet_get_string(&blen);
	chost = packet_get_string(NULL);
	cuser = packet_get_string(NULL);
	sig = packet_get_string(&slen);

	debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
	    cuser, chost, pkalg, slen);
#ifdef DEBUG_PK
	debug("signature:");
	buffer_init(&b);
	buffer_append(&b, sig, slen);
	buffer_dump(&b);
	buffer_free(&b);
#endif
	pktype = key_type_from_name(pkalg);
	if (pktype == KEY_UNSPEC) {
		/* this is perfectly legal */
		logit("userauth_hostbased: unsupported "
		    "public key algorithm: %s", pkalg);
		goto done;
	}
	key = key_from_blob(pkblob, blen);
	if (key == NULL) {
		error("userauth_hostbased: cannot decode key: %s", pkalg);
		goto done;
	}
	if (key->type != pktype) {
		error("userauth_hostbased: type mismatch for decoded key "
		    "(received %d, expected %d)", key->type, pktype);
		goto done;
	}
	service = datafellows & SSH_BUG_HBSERVICE ? __UNCONST("ssh-userauth") :
	    authctxt->service;
	buffer_init(&b);
	buffer_put_string(&b, session_id2, session_id2_len);
	/* reconstruct packet */
	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	buffer_put_cstring(&b, authctxt->user);
	buffer_put_cstring(&b, service);
	buffer_put_cstring(&b, "hostbased");
	buffer_put_string(&b, pkalg, alen);
	buffer_put_string(&b, pkblob, blen);
	buffer_put_cstring(&b, chost);
	buffer_put_cstring(&b, cuser);
#ifdef DEBUG_PK
	buffer_dump(&b);
#endif
	/* test for allowed key and correct signature */
	authenticated = 0;
	if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
	    PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
			buffer_len(&b))) == 1)
		authenticated = 1;

	buffer_free(&b);
done:
	debug2("userauth_hostbased: authenticated %d", authenticated);
	if (key != NULL)
		key_free(key);
	xfree(pkalg);
	xfree(pkblob);
	xfree(cuser);
	xfree(chost);
	xfree(sig);
	return authenticated;
}