| 1 | /* |
| 2 | * scpssh.c - SSH implementation for PuTTY Secure Copy |
| 3 | * Joris van Rantwijk, Aug 1999. |
| 4 | * Based on PuTTY ssh.c by Simon Tatham. |
| 5 | */ |
| 6 | |
| 7 | #include <stdio.h> |
| 8 | #include <stdlib.h> |
| 9 | #include <string.h> |
| 10 | #include <winsock.h> |
| 11 | |
| 12 | #include "putty.h" |
| 13 | #include "ssh.h" |
| 14 | #include "scp.h" |
| 15 | |
| 16 | #define SSH_MSG_DISCONNECT 1 |
| 17 | #define SSH_SMSG_PUBLIC_KEY 2 |
| 18 | #define SSH_CMSG_SESSION_KEY 3 |
| 19 | #define SSH_CMSG_USER 4 |
| 20 | #define SSH_CMSG_AUTH_PASSWORD 9 |
| 21 | #define SSH_CMSG_EXEC_CMD 13 |
| 22 | #define SSH_SMSG_SUCCESS 14 |
| 23 | #define SSH_SMSG_FAILURE 15 |
| 24 | #define SSH_CMSG_STDIN_DATA 16 |
| 25 | #define SSH_SMSG_STDOUT_DATA 17 |
| 26 | #define SSH_SMSG_STDERR_DATA 18 |
| 27 | #define SSH_CMSG_EOF 19 |
| 28 | #define SSH_SMSG_EXIT_STATUS 20 |
| 29 | #define SSH_CMSG_EXIT_CONFIRMATION 33 |
| 30 | #define SSH_MSG_DEBUG 36 |
| 31 | |
| 32 | #define GET_32BIT(cp) \ |
| 33 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
| 34 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
| 35 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
| 36 | ((unsigned long)(unsigned char)(cp)[3])) |
| 37 | |
| 38 | #define PUT_32BIT(cp, value) { \ |
| 39 | (cp)[0] = (value) >> 24; \ |
| 40 | (cp)[1] = (value) >> 16; \ |
| 41 | (cp)[2] = (value) >> 8; \ |
| 42 | (cp)[3] = (value); } |
| 43 | |
| 44 | static SOCKET s = INVALID_SOCKET; |
| 45 | |
| 46 | static unsigned char session_key[32]; |
| 47 | static struct ssh_cipher *cipher = NULL; |
| 48 | |
| 49 | static char *savedhost; |
| 50 | |
| 51 | struct Packet { |
| 52 | long length; |
| 53 | int type; |
| 54 | unsigned long crc; |
| 55 | unsigned char *data; |
| 56 | unsigned char *body; |
| 57 | long maxlen; |
| 58 | }; |
| 59 | |
| 60 | static struct Packet pktin = { 0, 0, 0, NULL, 0 }; |
| 61 | static struct Packet pktout = { 0, 0, 0, NULL, 0 }; |
| 62 | |
| 63 | |
| 64 | static void s_write (char *buf, int len) { |
| 65 | while (len > 0) { |
| 66 | int i = send (s, buf, len, 0); |
| 67 | noise_ultralight(i); |
| 68 | if (i <= 0) |
| 69 | fatalbox("Lost connection while sending"); |
| 70 | len -= i, buf += i; |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | static int s_read (char *buf, int len) { |
| 75 | int ret = 0; |
| 76 | while (len > 0) { |
| 77 | int i = recv (s, buf, len, 0); |
| 78 | noise_ultralight(i); |
| 79 | if (i > 0) |
| 80 | len -= i, buf += i, ret += i; |
| 81 | else |
| 82 | return i; |
| 83 | } |
| 84 | return ret; |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Read and decrypt one incoming SSH packet. |
| 89 | */ |
| 90 | static void get_packet() |
| 91 | { |
| 92 | unsigned char buf[4]; |
| 93 | int ret; |
| 94 | int len, pad, biglen; |
| 95 | |
| 96 | next_packet: |
| 97 | |
| 98 | pktin.type = 0; |
| 99 | pktin.length = 0; |
| 100 | |
| 101 | ret = s_read(buf, 4); |
| 102 | if (ret != 4) { |
| 103 | closesocket(s); |
| 104 | s = INVALID_SOCKET; |
| 105 | return; |
| 106 | } |
| 107 | |
| 108 | len = GET_32BIT(buf); |
| 109 | |
| 110 | #ifdef FWHACK |
| 111 | if (len == 0x52656d6f) { |
| 112 | len = 0x300; |
| 113 | } |
| 114 | #endif |
| 115 | |
| 116 | pad = 8 - (len % 8); |
| 117 | biglen = len + pad; |
| 118 | len -= 5; /* type and CRC */ |
| 119 | |
| 120 | pktin.length = len; |
| 121 | if (pktin.maxlen < biglen) { |
| 122 | pktin.maxlen = biglen; |
| 123 | pktin.data = (pktin.data == NULL) ? |
| 124 | smalloc(biglen) : srealloc(pktin.data, biglen); |
| 125 | } |
| 126 | |
| 127 | ret = s_read(pktin.data, biglen); |
| 128 | if (ret != biglen) { |
| 129 | closesocket(s); |
| 130 | s = INVALID_SOCKET; |
| 131 | return; |
| 132 | } |
| 133 | |
| 134 | if (cipher) |
| 135 | cipher->decrypt(pktin.data, biglen); |
| 136 | |
| 137 | pktin.type = pktin.data[pad]; |
| 138 | pktin.body = pktin.data + pad + 1; |
| 139 | |
| 140 | if (pktin.type == SSH_MSG_DEBUG) { |
| 141 | if (verbose) { |
| 142 | int len = GET_32BIT(pktin.body); |
| 143 | fprintf(stderr, "Remote: "); |
| 144 | fwrite(pktin.body + 4, len, 1, stderr); |
| 145 | fprintf(stderr, "\n"); |
| 146 | } |
| 147 | goto next_packet; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | static void s_wrpkt_start(int type, int len) { |
| 152 | int pad, biglen; |
| 153 | |
| 154 | len += 5; /* type and CRC */ |
| 155 | pad = 8 - (len%8); |
| 156 | biglen = len + pad; |
| 157 | |
| 158 | pktout.length = len-5; |
| 159 | if (pktout.maxlen < biglen) { |
| 160 | pktout.maxlen = biglen; |
| 161 | pktout.data = (pktout.data == NULL ? malloc(biglen+4) : |
| 162 | realloc(pktout.data, biglen+4)); |
| 163 | if (!pktout.data) |
| 164 | fatalbox("Out of memory"); |
| 165 | } |
| 166 | |
| 167 | pktout.type = type; |
| 168 | pktout.body = pktout.data+4+pad+1; |
| 169 | } |
| 170 | |
| 171 | static void s_wrpkt(void) { |
| 172 | int pad, len, biglen, i; |
| 173 | unsigned long crc; |
| 174 | |
| 175 | len = pktout.length + 5; /* type and CRC */ |
| 176 | pad = 8 - (len%8); |
| 177 | biglen = len + pad; |
| 178 | |
| 179 | pktout.body[-1] = pktout.type; |
| 180 | for (i=0; i<pad; i++) |
| 181 | pktout.data[i+4] = random_byte(); |
| 182 | crc = crc32(pktout.data+4, biglen-4); |
| 183 | PUT_32BIT(pktout.data+biglen, crc); |
| 184 | PUT_32BIT(pktout.data, len); |
| 185 | |
| 186 | if (cipher) |
| 187 | cipher->encrypt(pktout.data+4, biglen); |
| 188 | |
| 189 | s_write(pktout.data, biglen+4); |
| 190 | } |
| 191 | |
| 192 | static int do_ssh_init(void) { |
| 193 | char c; |
| 194 | char version[10]; |
| 195 | char vstring[40]; |
| 196 | int i; |
| 197 | |
| 198 | #ifdef FWHACK |
| 199 | i = 0; |
| 200 | while (s_read(&c, 1) == 1) { |
| 201 | if (c == 'S' && i < 2) i++; |
| 202 | else if (c == 'S' && i == 2) i = 2; |
| 203 | else if (c == 'H' && i == 2) break; |
| 204 | else i = 0; |
| 205 | } |
| 206 | #else |
| 207 | if (s_read(&c,1) != 1 || c != 'S') return 0; |
| 208 | if (s_read(&c,1) != 1 || c != 'S') return 0; |
| 209 | if (s_read(&c,1) != 1 || c != 'H') return 0; |
| 210 | #endif |
| 211 | if (s_read(&c,1) != 1 || c != '-') return 0; |
| 212 | i = 0; |
| 213 | while (1) { |
| 214 | if (s_read(&c,1) != 1) |
| 215 | return 0; |
| 216 | if (i >= 0) { |
| 217 | if (c == '-') { |
| 218 | version[i] = '\0'; |
| 219 | i = -1; |
| 220 | } else if (i < sizeof(version)-1) |
| 221 | version[i++] = c; |
| 222 | } |
| 223 | else if (c == '\n') |
| 224 | break; |
| 225 | } |
| 226 | |
| 227 | sprintf(vstring, "SSH-%s-7.7.7\n", |
| 228 | (strcmp(version, "1.5") <= 0 ? version : "1.5")); |
| 229 | s_write(vstring, strlen(vstring)); |
| 230 | return 1; |
| 231 | } |
| 232 | |
| 233 | |
| 234 | /* |
| 235 | * Login on the server and request execution of the command. |
| 236 | */ |
| 237 | static void ssh_login(char *username, char *cmd) |
| 238 | { |
| 239 | int i, j, len; |
| 240 | unsigned char session_id[16]; |
| 241 | unsigned char *rsabuf, *keystr1, *keystr2; |
| 242 | unsigned char cookie[8]; |
| 243 | struct RSAKey servkey, hostkey; |
| 244 | struct MD5Context md5c; |
| 245 | unsigned long supported_ciphers_mask; |
| 246 | int cipher_type; |
| 247 | |
| 248 | extern struct ssh_cipher ssh_3des; |
| 249 | extern struct ssh_cipher ssh_blowfish; |
| 250 | |
| 251 | get_packet(); |
| 252 | |
| 253 | if (pktin.type != SSH_SMSG_PUBLIC_KEY) |
| 254 | fatalbox("Public key packet not received"); |
| 255 | |
| 256 | memcpy(cookie, pktin.body, 8); |
| 257 | |
| 258 | MD5Init(&md5c); |
| 259 | |
| 260 | i = makekey(pktin.body+8, &servkey, &keystr1); |
| 261 | j = makekey(pktin.body+8+i, &hostkey, &keystr2); |
| 262 | |
| 263 | supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j); |
| 264 | |
| 265 | MD5Update(&md5c, keystr2, hostkey.bytes); |
| 266 | MD5Update(&md5c, keystr1, servkey.bytes); |
| 267 | MD5Update(&md5c, pktin.body, 8); |
| 268 | |
| 269 | MD5Final(session_id, &md5c); |
| 270 | |
| 271 | for (i=0; i<32; i++) |
| 272 | session_key[i] = random_byte(); |
| 273 | |
| 274 | len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes); |
| 275 | |
| 276 | rsabuf = malloc(len); |
| 277 | if (!rsabuf) |
| 278 | fatalbox("Out of memory"); |
| 279 | |
| 280 | verify_ssh_host_key(savedhost, &hostkey); |
| 281 | |
| 282 | for (i=0; i<32; i++) { |
| 283 | rsabuf[i] = session_key[i]; |
| 284 | if (i < 16) |
| 285 | rsabuf[i] ^= session_id[i]; |
| 286 | } |
| 287 | |
| 288 | if (hostkey.bytes > servkey.bytes) { |
| 289 | rsaencrypt(rsabuf, 32, &servkey); |
| 290 | rsaencrypt(rsabuf, servkey.bytes, &hostkey); |
| 291 | } else { |
| 292 | rsaencrypt(rsabuf, 32, &hostkey); |
| 293 | rsaencrypt(rsabuf, hostkey.bytes, &servkey); |
| 294 | } |
| 295 | |
| 296 | cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH : |
| 297 | SSH_CIPHER_3DES; |
| 298 | if ((supported_ciphers_mask & (1 << cipher_type)) == 0) { |
| 299 | fprintf(stderr, "Selected cipher not supported, falling back to 3DES\n"); |
| 300 | cipher_type = SSH_CIPHER_3DES; |
| 301 | } |
| 302 | |
| 303 | s_wrpkt_start(SSH_CMSG_SESSION_KEY, len+15); |
| 304 | pktout.body[0] = cipher_type; |
| 305 | memcpy(pktout.body+1, cookie, 8); |
| 306 | pktout.body[9] = (len*8) >> 8; |
| 307 | pktout.body[10] = (len*8) & 0xFF; |
| 308 | memcpy(pktout.body+11, rsabuf, len); |
| 309 | pktout.body[len+11] = pktout.body[len+12] = 0; /* protocol flags */ |
| 310 | pktout.body[len+13] = pktout.body[len+14] = 0; |
| 311 | s_wrpkt(); |
| 312 | |
| 313 | free(rsabuf); |
| 314 | |
| 315 | cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish : |
| 316 | &ssh_3des; |
| 317 | cipher->sesskey(session_key); |
| 318 | |
| 319 | get_packet(); |
| 320 | |
| 321 | if (pktin.type != SSH_SMSG_SUCCESS) |
| 322 | fatalbox("Encryption not successfully enabled"); |
| 323 | |
| 324 | if (verbose) |
| 325 | fprintf(stderr, "Logging in as \"%s\".\n", username); |
| 326 | s_wrpkt_start(SSH_CMSG_USER, 4+strlen(username)); |
| 327 | pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; |
| 328 | pktout.body[3] = strlen(username); |
| 329 | memcpy(pktout.body+4, username, strlen(username)); |
| 330 | s_wrpkt(); |
| 331 | |
| 332 | get_packet(); |
| 333 | |
| 334 | while (pktin.type == SSH_SMSG_FAILURE) { |
| 335 | char password[100]; |
| 336 | char prompt[200]; |
| 337 | sprintf(prompt, "%s@%s's password: ", username, savedhost); |
| 338 | ssh_get_password(prompt, password, 100); |
| 339 | s_wrpkt_start(SSH_CMSG_AUTH_PASSWORD, 4+strlen(password)); |
| 340 | pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; |
| 341 | pktout.body[3] = strlen(password); |
| 342 | memcpy(pktout.body+4, password, strlen(password)); |
| 343 | s_wrpkt(); |
| 344 | memset(password, 0, strlen(password)); |
| 345 | get_packet(); |
| 346 | if (pktin.type == SSH_SMSG_FAILURE) { |
| 347 | fprintf(stderr, "Access denied\n"); |
| 348 | } else if (pktin.type != SSH_SMSG_SUCCESS) { |
| 349 | fatalbox("Strange packet received, type %d", pktin.type); |
| 350 | } |
| 351 | } |
| 352 | |
| 353 | /* Execute command */ |
| 354 | if (verbose) |
| 355 | fprintf(stderr, "Sending command: %s\n", cmd); |
| 356 | i = strlen(cmd); |
| 357 | s_wrpkt_start(SSH_CMSG_EXEC_CMD, 4+i); |
| 358 | PUT_32BIT(pktout.body, i); |
| 359 | memcpy(pktout.body+4, cmd, i); |
| 360 | s_wrpkt(); |
| 361 | } |
| 362 | |
| 363 | |
| 364 | /* |
| 365 | * Receive a block of data over the SSH link. Block until |
| 366 | * all data is available. Return nr of bytes read (0 if lost connection). |
| 367 | */ |
| 368 | int ssh_recv(unsigned char *buf, int len) |
| 369 | { |
| 370 | static int pending_input_len = 0; |
| 371 | static unsigned char *pending_input_ptr; |
| 372 | int to_read = len; |
| 373 | |
| 374 | if (pending_input_len >= to_read) { |
| 375 | memcpy(buf, pending_input_ptr, to_read); |
| 376 | pending_input_ptr += to_read; |
| 377 | pending_input_len -= to_read; |
| 378 | return len; |
| 379 | } |
| 380 | |
| 381 | if (pending_input_len > 0) { |
| 382 | memcpy(buf, pending_input_ptr, pending_input_len); |
| 383 | buf += pending_input_len; |
| 384 | to_read -= pending_input_len; |
| 385 | pending_input_len = 0; |
| 386 | } |
| 387 | |
| 388 | if (s == INVALID_SOCKET) |
| 389 | return 0; |
| 390 | while (to_read > 0) { |
| 391 | get_packet(); |
| 392 | if (s == INVALID_SOCKET) |
| 393 | return 0; |
| 394 | if (pktin.type == SSH_SMSG_STDOUT_DATA) { |
| 395 | int plen = GET_32BIT(pktin.body); |
| 396 | if (plen <= to_read) { |
| 397 | memcpy(buf, pktin.body + 4, plen); |
| 398 | buf += plen; |
| 399 | to_read -= plen; |
| 400 | } else { |
| 401 | memcpy(buf, pktin.body + 4, to_read); |
| 402 | pending_input_len = plen - to_read; |
| 403 | pending_input_ptr = pktin.body + 4 + to_read; |
| 404 | to_read = 0; |
| 405 | } |
| 406 | } else if (pktin.type == SSH_SMSG_STDERR_DATA) { |
| 407 | int plen = GET_32BIT(pktin.body); |
| 408 | fwrite(pktin.body + 4, plen, 1, stderr); |
| 409 | } else if (pktin.type == SSH_MSG_DISCONNECT) { |
| 410 | } else if (pktin.type == SSH_SMSG_SUCCESS || |
| 411 | pktin.type == SSH_SMSG_FAILURE) { |
| 412 | } else if (pktin.type == SSH_SMSG_EXIT_STATUS) { |
| 413 | if (verbose) |
| 414 | fprintf(stderr, "Remote exit status %d\n", |
| 415 | GET_32BIT(pktin.body)); |
| 416 | s_wrpkt_start(SSH_CMSG_EXIT_CONFIRMATION, 0); |
| 417 | s_wrpkt(); |
| 418 | if (verbose) |
| 419 | fprintf(stderr, "Closing connection\n"); |
| 420 | closesocket(s); |
| 421 | s = INVALID_SOCKET; |
| 422 | } |
| 423 | } |
| 424 | |
| 425 | return len; |
| 426 | } |
| 427 | |
| 428 | |
| 429 | /* |
| 430 | * Send a block of data over the SSH link. |
| 431 | * Block until all data is sent. |
| 432 | */ |
| 433 | void ssh_send(unsigned char *buf, int len) |
| 434 | { |
| 435 | if (s == INVALID_SOCKET) |
| 436 | return; |
| 437 | s_wrpkt_start(SSH_CMSG_STDIN_DATA, 4 + len); |
| 438 | PUT_32BIT(pktout.body, len); |
| 439 | memcpy(pktout.body + 4, buf, len); |
| 440 | s_wrpkt(); |
| 441 | } |
| 442 | |
| 443 | |
| 444 | /* |
| 445 | * Send an EOF notification to the server. |
| 446 | */ |
| 447 | void ssh_send_eof(void) |
| 448 | { |
| 449 | if (s == INVALID_SOCKET) |
| 450 | return; |
| 451 | s_wrpkt_start(SSH_CMSG_EOF, 0); |
| 452 | s_wrpkt(); |
| 453 | } |
| 454 | |
| 455 | |
| 456 | /* |
| 457 | * Set up the connection, login on the remote host and |
| 458 | * start execution of a command. |
| 459 | * |
| 460 | * Returns an error message, or NULL on success. |
| 461 | * |
| 462 | * Also places the canonical host name into `realhost'. |
| 463 | */ |
| 464 | char *ssh_init(char *host, int port, char *cmd, char **realhost) { |
| 465 | SOCKADDR_IN addr; |
| 466 | struct hostent *h; |
| 467 | unsigned long a; |
| 468 | #ifdef FWHACK |
| 469 | char *FWhost; |
| 470 | int FWport; |
| 471 | #endif |
| 472 | |
| 473 | savedhost = malloc(1+strlen(host)); |
| 474 | if (!savedhost) |
| 475 | fatalbox("Out of memory"); |
| 476 | strcpy(savedhost, host); |
| 477 | |
| 478 | #ifdef FWHACK |
| 479 | FWhost = host; |
| 480 | FWport = port; |
| 481 | host = FWSTR; |
| 482 | port = 23; |
| 483 | #endif |
| 484 | |
| 485 | /* |
| 486 | * Try to find host. |
| 487 | */ |
| 488 | if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) { |
| 489 | if ( (h = gethostbyname(host)) == NULL) |
| 490 | switch (WSAGetLastError()) { |
| 491 | case WSAENETDOWN: return "Network is down"; |
| 492 | case WSAHOST_NOT_FOUND: case WSANO_DATA: |
| 493 | return "Host does not exist"; |
| 494 | case WSATRY_AGAIN: return "Host not found"; |
| 495 | default: return "gethostbyname: unknown error"; |
| 496 | } |
| 497 | memcpy (&a, h->h_addr, sizeof(a)); |
| 498 | *realhost = h->h_name; |
| 499 | } else |
| 500 | *realhost = host; |
| 501 | #ifdef FWHACK |
| 502 | *realhost = FWhost; |
| 503 | #endif |
| 504 | a = ntohl(a); |
| 505 | |
| 506 | if (port < 0) |
| 507 | port = 22; /* default ssh port */ |
| 508 | |
| 509 | /* |
| 510 | * Open socket. |
| 511 | */ |
| 512 | s = socket(AF_INET, SOCK_STREAM, 0); |
| 513 | if (s == INVALID_SOCKET) |
| 514 | switch (WSAGetLastError()) { |
| 515 | case WSAENETDOWN: return "Network is down"; |
| 516 | case WSAEAFNOSUPPORT: return "TCP/IP support not present"; |
| 517 | default: return "socket(): unknown error"; |
| 518 | } |
| 519 | |
| 520 | /* |
| 521 | * Bind to local address. |
| 522 | */ |
| 523 | addr.sin_family = AF_INET; |
| 524 | addr.sin_addr.s_addr = htonl(INADDR_ANY); |
| 525 | addr.sin_port = htons(0); |
| 526 | if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR) |
| 527 | switch (WSAGetLastError()) { |
| 528 | case WSAENETDOWN: return "Network is down"; |
| 529 | default: return "bind(): unknown error"; |
| 530 | } |
| 531 | |
| 532 | /* |
| 533 | * Connect to remote address. |
| 534 | */ |
| 535 | addr.sin_addr.s_addr = htonl(a); |
| 536 | addr.sin_port = htons((short)port); |
| 537 | if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR) |
| 538 | switch (WSAGetLastError()) { |
| 539 | case WSAENETDOWN: return "Network is down"; |
| 540 | case WSAECONNREFUSED: return "Connection refused"; |
| 541 | case WSAENETUNREACH: return "Network is unreachable"; |
| 542 | case WSAEHOSTUNREACH: return "No route to host"; |
| 543 | default: return "connect(): unknown error"; |
| 544 | } |
| 545 | |
| 546 | #ifdef FWHACK |
| 547 | send(s, "connect ", 8, 0); |
| 548 | send(s, FWhost, strlen(FWhost), 0); |
| 549 | { |
| 550 | char buf[20]; |
| 551 | sprintf(buf, " %d\n", FWport); |
| 552 | send (s, buf, strlen(buf), 0); |
| 553 | } |
| 554 | #endif |
| 555 | |
| 556 | random_init(); |
| 557 | |
| 558 | if (!do_ssh_init()) |
| 559 | return "Protocol initialisation error"; |
| 560 | |
| 561 | ssh_login(cfg.username, cmd); |
| 562 | |
| 563 | return NULL; |
| 564 | } |
| 565 | |
| 566 | /* end */ |