07d9aa13 |
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 */ |