452 lines
12 KiB
C
452 lines
12 KiB
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 1.11 2000/05/25 20:45:20 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_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr,
|
|
Buffer *client_kexinit, Buffer *server_kexinit)
|
|
{
|
|
int i;
|
|
int plen, dlen;
|
|
unsigned int klen, kout;
|
|
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;
|
|
unsigned char *kbuf;
|
|
unsigned char *hash;
|
|
|
|
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(&plen, 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);
|
|
DH_free(dh);
|
|
#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);
|
|
|
|
/* save session id */
|
|
session_id2_len = 20;
|
|
session_id2 = xmalloc(session_id2_len);
|
|
memcpy(session_id2, hash, session_id2_len);
|
|
}
|
|
|
|
void
|
|
ssh_kex2(char *host, struct sockaddr *hostaddr)
|
|
{
|
|
int i, plen;
|
|
Kex *kex;
|
|
Buffer *client_kexinit, *server_kexinit;
|
|
char *sprop[PROPOSAL_MAX];
|
|
|
|
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] =
|
|
(char *) cipher_name(SSH_CIPHER_3DES_CBC);
|
|
} else if (options.cipher == SSH_CIPHER_BLOWFISH) {
|
|
myproposal[PROPOSAL_ENC_ALGS_CTOS] =
|
|
myproposal[PROPOSAL_ENC_ALGS_STOC] =
|
|
(char *) 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";
|
|
}
|
|
|
|
/* buffers with raw kexinit messages */
|
|
server_kexinit = xmalloc(sizeof(*server_kexinit));
|
|
buffer_init(server_kexinit);
|
|
client_kexinit = kex_init(myproposal);
|
|
|
|
/* algorithm negotiation */
|
|
kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
|
|
kex = kex_choose_conf(myproposal, sprop, 0);
|
|
for (i = 0; i < PROPOSAL_MAX; i++)
|
|
xfree(sprop[i]);
|
|
|
|
/* server authentication and session key agreement */
|
|
ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit);
|
|
|
|
buffer_free(client_kexinit);
|
|
buffer_free(server_kexinit);
|
|
xfree(client_kexinit);
|
|
xfree(server_kexinit);
|
|
|
|
debug("Wait SSH2_MSG_NEWKEYS.");
|
|
packet_read_expect(&plen, 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");
|
|
}
|