[openssh.git] / sshconnect2.c

/*
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Markus Friedl.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: sshconnect2.c,v 1.10 2000/05/08 17:42:25 markus Exp $");

#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/dsa.h>
#include <openssl/md5.h>
#include <openssl/dh.h>
#include <openssl/hmac.h>

#include "ssh.h"
#include "xmalloc.h"
#include "rsa.h"
#include "buffer.h"
#include "packet.h"
#include "cipher.h"
#include "uidswap.h"
#include "compat.h"
#include "readconf.h"
#include "bufaux.h"
#include "ssh2.h"
#include "kex.h"
#include "myproposal.h"
#include "key.h"
#include "dsa.h"
#include "sshconnect.h"
#include "authfile.h"

/* import */
extern char *client_version_string;
extern char *server_version_string;
extern Options options;

/*
 * SSH2 key exchange
 */

unsigned char *session_id2 = NULL;
int session_id2_len = 0;

void
ssh_kex2(char *host, struct sockaddr *hostaddr)
{
	Kex *kex;
	char *cprop[PROPOSAL_MAX];
	char *sprop[PROPOSAL_MAX];
	Buffer *client_kexinit;
	Buffer *server_kexinit;
	int payload_len, dlen;
	unsigned int klen, kout;
	char *ptr;
	char *signature = NULL;
	unsigned int slen;
	char *server_host_key_blob = NULL;
	Key *server_host_key;
	unsigned int sbloblen;
	DH *dh;
	BIGNUM *dh_server_pub = 0;
	BIGNUM *shared_secret = 0;
	int i;
	unsigned char *kbuf;
	unsigned char *hash;

/* KEXINIT */

	debug("Sending KEX init.");
	if (options.ciphers != NULL) {
		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
		myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
	} else if (options.cipher == SSH_CIPHER_3DES) {
		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
		myproposal[PROPOSAL_ENC_ALGS_STOC] =
		    cipher_name(SSH_CIPHER_3DES_CBC);
	} else if (options.cipher == SSH_CIPHER_BLOWFISH) {
		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
		myproposal[PROPOSAL_ENC_ALGS_STOC] =
		    cipher_name(SSH_CIPHER_BLOWFISH_CBC);
	}
	if (options.compression) {
		myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
		myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
	} else {
		myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
		myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
	}
	for (i = 0; i < PROPOSAL_MAX; i++)
		cprop[i] = xstrdup(myproposal[i]);

	client_kexinit = kex_init(cprop);
	packet_start(SSH2_MSG_KEXINIT);
	packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));	
	packet_send();
	packet_write_wait();

	debug("done");

	packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);

	/* save payload for session_id */
	server_kexinit = xmalloc(sizeof(*server_kexinit));
	buffer_init(server_kexinit);
	ptr = packet_get_raw(&payload_len);
	buffer_append(server_kexinit, ptr, payload_len);

	/* skip cookie */
	for (i = 0; i < 16; i++)
		(void) packet_get_char();
	/* kex init proposal strings */
	for (i = 0; i < PROPOSAL_MAX; i++) {
		sprop[i] = packet_get_string(NULL);
		debug("got kexinit string: %s", sprop[i]);
	}
	i = (int) packet_get_char();
	debug("first kex follow == %d", i);
	i = packet_get_int();
	debug("reserved == %d", i);
	packet_done();

	debug("done read kexinit");
	kex = kex_choose_conf(cprop, sprop, 0);

/* KEXDH */

	debug("Sending SSH2_MSG_KEXDH_INIT.");

	/* generate and send 'e', client DH public key */
	dh = dh_new_group1();
	packet_start(SSH2_MSG_KEXDH_INIT);
	packet_put_bignum2(dh->pub_key);
	packet_send();
	packet_write_wait();

#ifdef DEBUG_KEXDH
	fprintf(stderr, "\np= ");
	bignum_print(dh->p);
	fprintf(stderr, "\ng= ");
	bignum_print(dh->g);
	fprintf(stderr, "\npub= ");
	bignum_print(dh->pub_key);
	fprintf(stderr, "\n");
	DHparams_print_fp(stderr, dh);
#endif

	debug("Wait SSH2_MSG_KEXDH_REPLY.");

	packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);

	debug("Got SSH2_MSG_KEXDH_REPLY.");

	/* key, cert */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");

	check_host_key(host, hostaddr, server_host_key,
	    options.user_hostfile2, options.system_hostfile2);

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

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

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

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

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_server_pub, dh);
#ifdef DEBUG_KEXDH
	debug("shared secret: len %d/%d", klen, kout);
	fprintf(stderr, "shared secret == ");
	for (i = 0; i< kout; i++)
		fprintf(stderr, "%02x", (kbuf[i])&0xff);
	fprintf(stderr, "\n");
#endif
	shared_secret = BN_new();

	BN_bin2bn(kbuf, kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	/* calc and verify H */
	hash = kex_hash(
	    client_version_string,
	    server_version_string,
	    buffer_ptr(client_kexinit), buffer_len(client_kexinit),
	    buffer_ptr(server_kexinit), buffer_len(server_kexinit),
	    server_host_key_blob, sbloblen,
	    dh->pub_key,
	    dh_server_pub,
	    shared_secret
	);
	xfree(server_host_key_blob);
	buffer_free(client_kexinit);
	buffer_free(server_kexinit);
	xfree(client_kexinit);
	xfree(server_kexinit);
#ifdef DEBUG_KEXDH
	fprintf(stderr, "hash == ");
	for (i = 0; i< 20; i++)
		fprintf(stderr, "%02x", (hash[i])&0xff);
	fprintf(stderr, "\n");
#endif
	if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
		fatal("dsa_verify failed for server_host_key");
	key_free(server_host_key);

	kex_derive_keys(kex, hash, shared_secret);
	packet_set_kex(kex);

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

	/* save session id */
	session_id2_len = 20;
	session_id2 = xmalloc(session_id2_len);
	memcpy(session_id2, hash, session_id2_len);

	debug("Wait SSH2_MSG_NEWKEYS.");
	packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
	packet_done();
	debug("GOT SSH2_MSG_NEWKEYS.");

	debug("send SSH2_MSG_NEWKEYS.");
	packet_start(SSH2_MSG_NEWKEYS);
	packet_send();
	packet_write_wait();
	debug("done: send SSH2_MSG_NEWKEYS.");

#ifdef DEBUG_KEXDH
	/* send 1st encrypted/maced/compressed message */
	packet_start(SSH2_MSG_IGNORE);
	packet_put_cstring("markus");
	packet_send();
	packet_write_wait();
#endif
	debug("done: KEX2.");
}
/*
 * Authenticate user
 */
int
ssh2_try_passwd(const char *server_user, const char *host, const char *service)
{
	static int attempt = 0;
	char prompt[80];
	char *password;

	if (attempt++ > options.number_of_password_prompts)
		return 0;

	snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
	    server_user, host);
	password = read_passphrase(prompt, 0);
	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	packet_put_cstring(server_user);
	packet_put_cstring(service);
	packet_put_cstring("password");
	packet_put_char(0);
	packet_put_cstring(password);
	memset(password, 0, strlen(password));
	xfree(password);
	packet_send();
	packet_write_wait();
	return 1;
}

int
ssh2_try_pubkey(char *filename,
    const char *server_user, const char *host, const char *service)
{
	Buffer b;
	Key *k;
	unsigned char *blob, *signature;
	int bloblen, slen;
	struct stat st;

	if (stat(filename, &st) != 0) {
		debug("key does not exist: %s", filename);
		return 0;
	}
	debug("try pubkey: %s", filename);

	k = key_new(KEY_DSA);
	if (!load_private_key(filename, "", k, NULL)) {
		int success = 0;
		char *passphrase;
		char prompt[300];
		snprintf(prompt, sizeof prompt,
		     "Enter passphrase for DSA key '%.100s': ",
		     filename);
		passphrase = read_passphrase(prompt, 0);
		success = load_private_key(filename, passphrase, k, NULL);
		memset(passphrase, 0, strlen(passphrase));
		xfree(passphrase);
		if (!success)
			return 0;
	}
	dsa_make_key_blob(k, &blob, &bloblen);

	/* data to be signed */
	buffer_init(&b);
	buffer_append(&b, session_id2, session_id2_len);
	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	buffer_put_cstring(&b, server_user);
	buffer_put_cstring(&b,
	    datafellows & SSH_BUG_PUBKEYAUTH ?
	    "ssh-userauth" :
	    service);
	buffer_put_cstring(&b, "publickey");
	buffer_put_char(&b, 1);
	buffer_put_cstring(&b, KEX_DSS); 
	buffer_put_string(&b, blob, bloblen);

	/* generate signature */
	dsa_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
	key_free(k);
#ifdef DEBUG_DSS
	buffer_dump(&b);
#endif
	if (datafellows & SSH_BUG_PUBKEYAUTH) {
		/* e.g. ssh-2.0.13: data-to-be-signed != data-on-the-wire */
		buffer_clear(&b);
		buffer_append(&b, session_id2, session_id2_len);
		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
		buffer_put_cstring(&b, server_user);
		buffer_put_cstring(&b, service);
		buffer_put_cstring(&b, "publickey");
		buffer_put_char(&b, 1);
		buffer_put_cstring(&b, KEX_DSS); 
		buffer_put_string(&b, blob, bloblen);
	}
	xfree(blob);
	/* append signature */
	buffer_put_string(&b, signature, slen);
	xfree(signature);

	/* skip session id and packet type */
	if (buffer_len(&b) < session_id2_len + 1)
		fatal("ssh2_try_pubkey: internal error");
	buffer_consume(&b, session_id2_len + 1);

	/* put remaining data from buffer into packet */
	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	packet_put_raw(buffer_ptr(&b), buffer_len(&b));
	buffer_free(&b);

	/* send */
	packet_send();
	packet_write_wait();
	return 1;
}

void
ssh_userauth2(const char *server_user, char *host)
{
	int type;
	int plen;
	int sent;
	unsigned int dlen;
	int partial;
	int i = 0;
	char *auths;
	char *service = "ssh-connection";		/* service name */

	debug("send SSH2_MSG_SERVICE_REQUEST");
	packet_start(SSH2_MSG_SERVICE_REQUEST);
	packet_put_cstring("ssh-userauth");
	packet_send();
	packet_write_wait();

	type = packet_read(&plen);
	if (type != SSH2_MSG_SERVICE_ACCEPT) {
		fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
	}
	if (packet_remaining() > 0) {
		char *reply = packet_get_string(&plen);
		debug("service_accept: %s", reply);
		xfree(reply);
	} else {
		/* payload empty for ssh-2.0.13 ?? */
		debug("buggy server: service_accept w/o service");
	}
	packet_done();
	debug("got SSH2_MSG_SERVICE_ACCEPT");

	/* INITIAL request for auth */
	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	packet_put_cstring(server_user);
	packet_put_cstring(service);
	packet_put_cstring("none");
	packet_send();
	packet_write_wait();

	for (;;) {
		sent = 0;
		type = packet_read(&plen);
		if (type == SSH2_MSG_USERAUTH_SUCCESS)
			break;
		if (type != SSH2_MSG_USERAUTH_FAILURE)
			fatal("access denied: %d", type);
		/* SSH2_MSG_USERAUTH_FAILURE means: try again */
		auths = packet_get_string(&dlen);
		debug("authentications that can continue: %s", auths);
		partial = packet_get_char();
		packet_done();
		if (partial)
			debug("partial success");
		if (options.dsa_authentication &&
		    strstr(auths, "publickey") != NULL) {
			while (i < options.num_identity_files2) {
				sent = ssh2_try_pubkey(
				    options.identity_files2[i++],
				    server_user, host, service);
				if (sent)
					break;
			}
		}
		if (!sent) {
			if (options.password_authentication &&
			    !options.batch_mode &&
			    strstr(auths, "password") != NULL) {
				sent = ssh2_try_passwd(server_user, host, service);
			}
		}
		if (!sent)
			fatal("Permission denied (%s).", auths);
		xfree(auths);
	}
	packet_done();
	debug("ssh-userauth2 successfull");
}
Commit	Line	Data
a306f2dd	1	/*
	2	* Copyright (c) 2000 Markus Friedl. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	* 3. All advertising materials mentioning features or use of this software
	13	* must display the following acknowledgement:
	14	* This product includes software developed by Markus Friedl.
	15	* 4. The name of the author may not be used to endorse or promote products
	16	* derived from this software without specific prior written permission.
	17	*
	18	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	19	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	20	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	21	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	22	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	23	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	24	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	25	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	26	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	27	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	28	*/
	29
	30	#include "includes.h"
d0c832f3	31	RCSID("$OpenBSD: sshconnect2.c,v 1.10 2000/05/08 17:42:25 markus Exp $");
a306f2dd	32
	33	#include <openssl/bn.h>
	34	#include <openssl/rsa.h>
	35	#include <openssl/dsa.h>
	36	#include <openssl/md5.h>
	37	#include <openssl/dh.h>
	38	#include <openssl/hmac.h>
	39
	40	#include "ssh.h"
	41	#include "xmalloc.h"
	42	#include "rsa.h"
	43	#include "buffer.h"
	44	#include "packet.h"
	45	#include "cipher.h"
	46	#include "uidswap.h"
	47	#include "compat.h"
	48	#include "readconf.h"
	49	#include "bufaux.h"
	50	#include "ssh2.h"
	51	#include "kex.h"
	52	#include "myproposal.h"
	53	#include "key.h"
	54	#include "dsa.h"
	55	#include "sshconnect.h"
	56	#include "authfile.h"
	57
	58	/* import */
	59	extern char *client_version_string;
	60	extern char *server_version_string;
	61	extern Options options;
	62
	63	/*
	64	* SSH2 key exchange
	65	*/
	66
	67	unsigned char *session_id2 = NULL;
	68	int session_id2_len = 0;
	69
	70	void
	71	ssh_kex2(char host, struct sockaddr hostaddr)
	72	{
	73	Kex *kex;
	74	char *cprop[PROPOSAL_MAX];
	75	char *sprop[PROPOSAL_MAX];
	76	Buffer *client_kexinit;
	77	Buffer *server_kexinit;
	78	int payload_len, dlen;
	79	unsigned int klen, kout;
	80	char *ptr;
	81	char *signature = NULL;
	82	unsigned int slen;
	83	char *server_host_key_blob = NULL;
	84	Key *server_host_key;
	85	unsigned int sbloblen;
	86	DH *dh;
	87	BIGNUM *dh_server_pub = 0;
	88	BIGNUM *shared_secret = 0;
	89	int i;
	90	unsigned char *kbuf;
	91	unsigned char *hash;
	92
	93	/* KEXINIT */
	94
	95	debug("Sending KEX init.");
96	if (options.ciphers != NULL) {
97	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
98	myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
d0c832f3	99	} else if (options.cipher == SSH_CIPHER_3DES) {
a306f2dd	100	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
d0c832f3	101	myproposal[PROPOSAL_ENC_ALGS_STOC] =
	102	cipher_name(SSH_CIPHER_3DES_CBC);
	103	} else if (options.cipher == SSH_CIPHER_BLOWFISH) {
	104	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
	105	myproposal[PROPOSAL_ENC_ALGS_STOC] =
	106	cipher_name(SSH_CIPHER_BLOWFISH_CBC);
a306f2dd	107	}
	108	if (options.compression) {
	109	myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
	110	myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
	111	} else {
	112	myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
	113	myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
	114	}
	115	for (i = 0; i < PROPOSAL_MAX; i++)
	116	cprop[i] = xstrdup(myproposal[i]);
	117
	118	client_kexinit = kex_init(cprop);
	119	packet_start(SSH2_MSG_KEXINIT);
	120	packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
	121	packet_send();
	122	packet_write_wait();
	123
	124	debug("done");
	125
	126	packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
	127
	128	/* save payload for session_id */
	129	server_kexinit = xmalloc(sizeof(*server_kexinit));
	130	buffer_init(server_kexinit);
	131	ptr = packet_get_raw(&payload_len);
	132	buffer_append(server_kexinit, ptr, payload_len);
	133
	134	/* skip cookie */
	135	for (i = 0; i < 16; i++)
	136	(void) packet_get_char();
	137	/* kex init proposal strings */
	138	for (i = 0; i < PROPOSAL_MAX; i++) {
	139	sprop[i] = packet_get_string(NULL);
	140	debug("got kexinit string: %s", sprop[i]);
	141	}
	142	i = (int) packet_get_char();
	143	debug("first kex follow == %d", i);
	144	i = packet_get_int();
	145	debug("reserved == %d", i);
	146	packet_done();
	147
	148	debug("done read kexinit");
	149	kex = kex_choose_conf(cprop, sprop, 0);
	150
	151	/* KEXDH */
	152
	153	debug("Sending SSH2_MSG_KEXDH_INIT.");
	154
	155	/* generate and send 'e', client DH public key */
	156	dh = dh_new_group1();
	157	packet_start(SSH2_MSG_KEXDH_INIT);
	158	packet_put_bignum2(dh->pub_key);
	159	packet_send();
	160	packet_write_wait();
	161
	162	#ifdef DEBUG_KEXDH
	163	fprintf(stderr, "\np= ");
	164	bignum_print(dh->p);
	165	fprintf(stderr, "\ng= ");
	166	bignum_print(dh->g);
	167	fprintf(stderr, "\npub= ");
	168	bignum_print(dh->pub_key);
	169	fprintf(stderr, "\n");
	170	DHparams_print_fp(stderr, dh);
171	#endif
172
173	debug("Wait SSH2_MSG_KEXDH_REPLY.");
174
175	packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
176
177	debug("Got SSH2_MSG_KEXDH_REPLY.");
178
179	/* key, cert */
180	server_host_key_blob = packet_get_string(&sbloblen);
181	server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
182	if (server_host_key == NULL)
183	fatal("cannot decode server_host_key_blob");
184
185	check_host_key(host, hostaddr, server_host_key,
186	options.user_hostfile2, options.system_hostfile2);
187
188	/* DH paramter f, server public DH key */
189	dh_server_pub = BN_new();
190	if (dh_server_pub == NULL)
191	fatal("dh_server_pub == NULL");
192	packet_get_bignum2(dh_server_pub, &dlen);
193
194	#ifdef DEBUG_KEXDH
195	fprintf(stderr, "\ndh_server_pub= ");
196	bignum_print(dh_server_pub);
197	fprintf(stderr, "\n");
198	debug("bits %d", BN_num_bits(dh_server_pub));
199	#endif
200
201	/* signed H */
202	signature = packet_get_string(&slen);
203	packet_done();
204
205	if (!dh_pub_is_valid(dh, dh_server_pub))
206	packet_disconnect("bad server public DH value");
207
208	klen = DH_size(dh);
209	kbuf = xmalloc(klen);
210	kout = DH_compute_key(kbuf, dh_server_pub, dh);
211	#ifdef DEBUG_KEXDH
212	debug("shared secret: len %d/%d", klen, kout);
213	fprintf(stderr, "shared secret == ");
214	for (i = 0; i< kout; i++)
215	fprintf(stderr, "%02x", (kbuf[i])&0xff);
216	fprintf(stderr, "\n");
217	#endif
218	shared_secret = BN_new();
219
220	BN_bin2bn(kbuf, kout, shared_secret);
221	memset(kbuf, 0, klen);
222	xfree(kbuf);
223
224	/* calc and verify H */
225	hash = kex_hash(
226	client_version_string,
227	server_version_string,
228	buffer_ptr(client_kexinit), buffer_len(client_kexinit),
229	buffer_ptr(server_kexinit), buffer_len(server_kexinit),
230	server_host_key_blob, sbloblen,
231	dh->pub_key,
232	dh_server_pub,
233	shared_secret
234	);
235	xfree(server_host_key_blob);
236	buffer_free(client_kexinit);
237	buffer_free(server_kexinit);
238	xfree(client_kexinit);
239	xfree(server_kexinit);
240	#ifdef DEBUG_KEXDH
241	fprintf(stderr, "hash == ");
242	for (i = 0; i< 20; i++)
243	fprintf(stderr, "%02x", (hash[i])&0xff);
244	fprintf(stderr, "\n");
245	#endif
246	if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
247	fatal("dsa_verify failed for server_host_key");
248	key_free(server_host_key);
249
250	kex_derive_keys(kex, hash, shared_secret);
251	packet_set_kex(kex);
252
253	/* have keys, free DH */
254	DH_free(dh);
255
256	/* save session id */
257	session_id2_len = 20;
258	session_id2 = xmalloc(session_id2_len);
259	memcpy(session_id2, hash, session_id2_len);
260
261	debug("Wait SSH2_MSG_NEWKEYS.");
262	packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
263	packet_done();
264	debug("GOT SSH2_MSG_NEWKEYS.");
265
266	debug("send SSH2_MSG_NEWKEYS.");
267	packet_start(SSH2_MSG_NEWKEYS);
268	packet_send();
269	packet_write_wait();
270	debug("done: send SSH2_MSG_NEWKEYS.");
271
272	#ifdef DEBUG_KEXDH
273	/* send 1st encrypted/maced/compressed message */
274	packet_start(SSH2_MSG_IGNORE);
275	packet_put_cstring("markus");
276	packet_send();
277	packet_write_wait();
278	#endif
279	debug("done: KEX2.");
280	}
281	/*
282	* Authenticate user
283	*/
284	int
285	ssh2_try_passwd(const char server_user, const char host, const char *service)
286	{
1d1ffb87	287	static int attempt = 0;
a306f2dd	288	char prompt[80];
	289	char *password;
	290
1d1ffb87	291	if (attempt++ > options.number_of_password_prompts)
	292	return 0;
	293
a306f2dd	294	snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
	295	server_user, host);
	296	password = read_passphrase(prompt, 0);
	297	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	298	packet_put_cstring(server_user);
	299	packet_put_cstring(service);
	300	packet_put_cstring("password");
	301	packet_put_char(0);
	302	packet_put_cstring(password);
	303	memset(password, 0, strlen(password));
	304	xfree(password);
	305	packet_send();
	306	packet_write_wait();
	307	return 1;
	308	}
	309
	310	int
	311	ssh2_try_pubkey(char *filename,
	312	const char server_user, const char host, const char *service)
	313	{
	314	Buffer b;
	315	Key *k;
	316	unsigned char blob, signature;
	317	int bloblen, slen;
0fbe8c74	318	struct stat st;
a306f2dd	319
0fbe8c74	320	if (stat(filename, &st) != 0) {
	321	debug("key does not exist: %s", filename);
	322	return 0;
	323	}
a306f2dd	324	debug("try pubkey: %s", filename);
	325
	326	k = key_new(KEY_DSA);
	327	if (!load_private_key(filename, "", k, NULL)) {
	328	int success = 0;
	329	char *passphrase;
	330	char prompt[300];
0fbe8c74	331	snprintf(prompt, sizeof prompt,
a306f2dd	332	"Enter passphrase for DSA key '%.100s': ",
0fbe8c74	333	filename);
a306f2dd	334	passphrase = read_passphrase(prompt, 0);
	335	success = load_private_key(filename, passphrase, k, NULL);
	336	memset(passphrase, 0, strlen(passphrase));
	337	xfree(passphrase);
	338	if (!success)
	339	return 0;
	340	}
	341	dsa_make_key_blob(k, &blob, &bloblen);
	342
	343	/* data to be signed */
	344	buffer_init(&b);
	345	buffer_append(&b, session_id2, session_id2_len);
	346	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	347	buffer_put_cstring(&b, server_user);
d0c832f3	348	buffer_put_cstring(&b,
	349	datafellows & SSH_BUG_PUBKEYAUTH ?
	350	"ssh-userauth" :
	351	service);
a306f2dd	352	buffer_put_cstring(&b, "publickey");
	353	buffer_put_char(&b, 1);
	354	buffer_put_cstring(&b, KEX_DSS);
	355	buffer_put_string(&b, blob, bloblen);
a306f2dd	356
	357	/* generate signature */
	358	dsa_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
	359	key_free(k);
	360	#ifdef DEBUG_DSS
	361	buffer_dump(&b);
	362	#endif
d0c832f3	363	if (datafellows & SSH_BUG_PUBKEYAUTH) {
	364	/* e.g. ssh-2.0.13: data-to-be-signed != data-on-the-wire */
	365	buffer_clear(&b);
	366	buffer_append(&b, session_id2, session_id2_len);
	367	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
	368	buffer_put_cstring(&b, server_user);
	369	buffer_put_cstring(&b, service);
	370	buffer_put_cstring(&b, "publickey");
	371	buffer_put_char(&b, 1);
	372	buffer_put_cstring(&b, KEX_DSS);
	373	buffer_put_string(&b, blob, bloblen);
	374	}
	375	xfree(blob);
a306f2dd	376	/* append signature */
	377	buffer_put_string(&b, signature, slen);
	378	xfree(signature);
	379
	380	/* skip session id and packet type */
	381	if (buffer_len(&b) < session_id2_len + 1)
	382	fatal("ssh2_try_pubkey: internal error");
	383	buffer_consume(&b, session_id2_len + 1);
	384
	385	/* put remaining data from buffer into packet */
	386	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	387	packet_put_raw(buffer_ptr(&b), buffer_len(&b));
	388	buffer_free(&b);
	389
	390	/* send */
	391	packet_send();
	392	packet_write_wait();
	393	return 1;
	394	}
	395
	396	void
	397	ssh_userauth2(const char server_user, char host)
	398	{
	399	int type;
	400	int plen;
	401	int sent;
	402	unsigned int dlen;
	403	int partial;
	404	int i = 0;
	405	char *auths;
	406	char service = "ssh-connection"; / service name */
	407
	408	debug("send SSH2_MSG_SERVICE_REQUEST");
	409	packet_start(SSH2_MSG_SERVICE_REQUEST);
	410	packet_put_cstring("ssh-userauth");
	411	packet_send();
	412	packet_write_wait();
	413
	414	type = packet_read(&plen);
	415	if (type != SSH2_MSG_SERVICE_ACCEPT) {
	416	fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
	417	}
	418	if (packet_remaining() > 0) {
	419	char *reply = packet_get_string(&plen);
	420	debug("service_accept: %s", reply);
	421	xfree(reply);
	422	} else {
	423	/* payload empty for ssh-2.0.13 ?? */
f6cde515	424	debug("buggy server: service_accept w/o service");
a306f2dd	425	}
	426	packet_done();
	427	debug("got SSH2_MSG_SERVICE_ACCEPT");
	428
	429	/* INITIAL request for auth */
	430	packet_start(SSH2_MSG_USERAUTH_REQUEST);
	431	packet_put_cstring(server_user);
	432	packet_put_cstring(service);
	433	packet_put_cstring("none");
	434	packet_send();
	435	packet_write_wait();
	436
	437	for (;;) {
	438	sent = 0;
	439	type = packet_read(&plen);
	440	if (type == SSH2_MSG_USERAUTH_SUCCESS)
	441	break;
	442	if (type != SSH2_MSG_USERAUTH_FAILURE)
	443	fatal("access denied: %d", type);
	444	/* SSH2_MSG_USERAUTH_FAILURE means: try again */
	445	auths = packet_get_string(&dlen);
	446	debug("authentications that can continue: %s", auths);
	447	partial = packet_get_char();
	448	packet_done();
	449	if (partial)
	450	debug("partial success");
1d1ffb87	451	if (options.dsa_authentication &&
a306f2dd	452	strstr(auths, "publickey") != NULL) {
	453	while (i < options.num_identity_files2) {
	454	sent = ssh2_try_pubkey(
	455	options.identity_files2[i++],
	456	server_user, host, service);
	457	if (sent)
	458	break;
	459	}
	460	}
	461	if (!sent) {
	462	if (options.password_authentication &&
	463	!options.batch_mode &&
	464	strstr(auths, "password") != NULL) {
	465	sent = ssh2_try_passwd(server_user, host, service);
	466	}
	467	}
	468	if (!sent)
	469	fatal("Permission denied (%s).", auths);
	470	xfree(auths);
	471	}
	472	packet_done();
	473	debug("ssh-userauth2 successfull");
	474	}