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 |
96b9dc0a |
30 | #define SSH_MSG_IGNORE 32 |
07d9aa13 |
31 | #define SSH_MSG_DEBUG 36 |
32 | |
33 | #define GET_32BIT(cp) \ |
34 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
35 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
36 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
37 | ((unsigned long)(unsigned char)(cp)[3])) |
38 | |
39 | #define PUT_32BIT(cp, value) { \ |
c51a56e2 |
40 | (cp)[0] = (unsigned char)((value) >> 24); \ |
41 | (cp)[1] = (unsigned char)((value) >> 16); \ |
42 | (cp)[2] = (unsigned char)((value) >> 8); \ |
43 | (cp)[3] = (unsigned char)(value); } |
07d9aa13 |
44 | |
45 | static SOCKET s = INVALID_SOCKET; |
46 | |
47 | static unsigned char session_key[32]; |
48 | static struct ssh_cipher *cipher = NULL; |
49 | |
50 | static char *savedhost; |
51 | |
52 | struct Packet { |
53 | long length; |
54 | int type; |
55 | unsigned long crc; |
56 | unsigned char *data; |
57 | unsigned char *body; |
58 | long maxlen; |
59 | }; |
60 | |
61 | static struct Packet pktin = { 0, 0, 0, NULL, 0 }; |
62 | static struct Packet pktout = { 0, 0, 0, NULL, 0 }; |
63 | |
64 | |
65 | static void s_write (char *buf, int len) { |
66 | while (len > 0) { |
67 | int i = send (s, buf, len, 0); |
68 | noise_ultralight(i); |
69 | if (i <= 0) |
70 | fatalbox("Lost connection while sending"); |
71 | len -= i, buf += i; |
72 | } |
73 | } |
74 | |
75 | static int s_read (char *buf, int len) { |
76 | int ret = 0; |
77 | while (len > 0) { |
78 | int i = recv (s, buf, len, 0); |
79 | noise_ultralight(i); |
80 | if (i > 0) |
81 | len -= i, buf += i, ret += i; |
82 | else |
83 | return i; |
84 | } |
85 | return ret; |
86 | } |
87 | |
88 | /* |
89 | * Read and decrypt one incoming SSH packet. |
90 | */ |
996c8c3b |
91 | static void get_packet(void) |
07d9aa13 |
92 | { |
93 | unsigned char buf[4]; |
94 | int ret; |
95 | int len, pad, biglen; |
96 | |
97 | next_packet: |
98 | |
99 | pktin.type = 0; |
100 | pktin.length = 0; |
101 | |
102 | ret = s_read(buf, 4); |
103 | if (ret != 4) { |
104 | closesocket(s); |
105 | s = INVALID_SOCKET; |
106 | return; |
107 | } |
108 | |
109 | len = GET_32BIT(buf); |
110 | |
111 | #ifdef FWHACK |
112 | if (len == 0x52656d6f) { |
113 | len = 0x300; |
114 | } |
115 | #endif |
116 | |
117 | pad = 8 - (len % 8); |
118 | biglen = len + pad; |
119 | len -= 5; /* type and CRC */ |
120 | |
121 | pktin.length = len; |
122 | if (pktin.maxlen < biglen) { |
123 | pktin.maxlen = biglen; |
124 | pktin.data = (pktin.data == NULL) ? |
125 | smalloc(biglen) : srealloc(pktin.data, biglen); |
126 | } |
127 | |
128 | ret = s_read(pktin.data, biglen); |
129 | if (ret != biglen) { |
130 | closesocket(s); |
131 | s = INVALID_SOCKET; |
132 | return; |
133 | } |
134 | |
135 | if (cipher) |
136 | cipher->decrypt(pktin.data, biglen); |
137 | |
138 | pktin.type = pktin.data[pad]; |
139 | pktin.body = pktin.data + pad + 1; |
140 | |
141 | if (pktin.type == SSH_MSG_DEBUG) { |
142 | if (verbose) { |
143 | int len = GET_32BIT(pktin.body); |
144 | fprintf(stderr, "Remote: "); |
145 | fwrite(pktin.body + 4, len, 1, stderr); |
146 | fprintf(stderr, "\n"); |
147 | } |
148 | goto next_packet; |
149 | } |
96b9dc0a |
150 | if (pktin.type == SSH_MSG_IGNORE) { |
151 | goto next_packet; |
152 | } |
07d9aa13 |
153 | } |
154 | |
155 | static void s_wrpkt_start(int type, int len) { |
156 | int pad, biglen; |
157 | |
158 | len += 5; /* type and CRC */ |
159 | pad = 8 - (len%8); |
160 | biglen = len + pad; |
161 | |
162 | pktout.length = len-5; |
163 | if (pktout.maxlen < biglen) { |
164 | pktout.maxlen = biglen; |
165 | pktout.data = (pktout.data == NULL ? malloc(biglen+4) : |
166 | realloc(pktout.data, biglen+4)); |
167 | if (!pktout.data) |
168 | fatalbox("Out of memory"); |
169 | } |
170 | |
171 | pktout.type = type; |
172 | pktout.body = pktout.data+4+pad+1; |
173 | } |
174 | |
175 | static void s_wrpkt(void) { |
176 | int pad, len, biglen, i; |
177 | unsigned long crc; |
178 | |
179 | len = pktout.length + 5; /* type and CRC */ |
180 | pad = 8 - (len%8); |
181 | biglen = len + pad; |
182 | |
183 | pktout.body[-1] = pktout.type; |
184 | for (i=0; i<pad; i++) |
185 | pktout.data[i+4] = random_byte(); |
186 | crc = crc32(pktout.data+4, biglen-4); |
187 | PUT_32BIT(pktout.data+biglen, crc); |
188 | PUT_32BIT(pktout.data, len); |
189 | |
190 | if (cipher) |
191 | cipher->encrypt(pktout.data+4, biglen); |
192 | |
193 | s_write(pktout.data, biglen+4); |
194 | } |
195 | |
196 | static int do_ssh_init(void) { |
197 | char c; |
198 | char version[10]; |
199 | char vstring[40]; |
200 | int i; |
201 | |
202 | #ifdef FWHACK |
203 | i = 0; |
204 | while (s_read(&c, 1) == 1) { |
205 | if (c == 'S' && i < 2) i++; |
206 | else if (c == 'S' && i == 2) i = 2; |
207 | else if (c == 'H' && i == 2) break; |
208 | else i = 0; |
209 | } |
210 | #else |
211 | if (s_read(&c,1) != 1 || c != 'S') return 0; |
212 | if (s_read(&c,1) != 1 || c != 'S') return 0; |
213 | if (s_read(&c,1) != 1 || c != 'H') return 0; |
214 | #endif |
215 | if (s_read(&c,1) != 1 || c != '-') return 0; |
216 | i = 0; |
217 | while (1) { |
218 | if (s_read(&c,1) != 1) |
219 | return 0; |
220 | if (i >= 0) { |
221 | if (c == '-') { |
222 | version[i] = '\0'; |
223 | i = -1; |
224 | } else if (i < sizeof(version)-1) |
225 | version[i++] = c; |
226 | } |
227 | else if (c == '\n') |
228 | break; |
229 | } |
230 | |
231 | sprintf(vstring, "SSH-%s-7.7.7\n", |
232 | (strcmp(version, "1.5") <= 0 ? version : "1.5")); |
233 | s_write(vstring, strlen(vstring)); |
234 | return 1; |
235 | } |
236 | |
237 | |
238 | /* |
239 | * Login on the server and request execution of the command. |
240 | */ |
241 | static void ssh_login(char *username, char *cmd) |
242 | { |
243 | int i, j, len; |
244 | unsigned char session_id[16]; |
245 | unsigned char *rsabuf, *keystr1, *keystr2; |
246 | unsigned char cookie[8]; |
247 | struct RSAKey servkey, hostkey; |
248 | struct MD5Context md5c; |
249 | unsigned long supported_ciphers_mask; |
250 | int cipher_type; |
251 | |
252 | extern struct ssh_cipher ssh_3des; |
253 | extern struct ssh_cipher ssh_blowfish; |
254 | |
255 | get_packet(); |
256 | |
257 | if (pktin.type != SSH_SMSG_PUBLIC_KEY) |
258 | fatalbox("Public key packet not received"); |
259 | |
260 | memcpy(cookie, pktin.body, 8); |
261 | |
262 | MD5Init(&md5c); |
263 | |
264 | i = makekey(pktin.body+8, &servkey, &keystr1); |
265 | j = makekey(pktin.body+8+i, &hostkey, &keystr2); |
266 | |
267 | supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j); |
268 | |
269 | MD5Update(&md5c, keystr2, hostkey.bytes); |
270 | MD5Update(&md5c, keystr1, servkey.bytes); |
271 | MD5Update(&md5c, pktin.body, 8); |
272 | |
273 | MD5Final(session_id, &md5c); |
274 | |
275 | for (i=0; i<32; i++) |
276 | session_key[i] = random_byte(); |
277 | |
278 | len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes); |
279 | |
280 | rsabuf = malloc(len); |
281 | if (!rsabuf) |
282 | fatalbox("Out of memory"); |
283 | |
89ee5268 |
284 | /* |
285 | * Verify the host key. |
286 | */ |
287 | { |
288 | /* |
289 | * First format the key into a string. |
290 | */ |
291 | int len = rsastr_len(&hostkey); |
292 | char *keystr = malloc(len); |
293 | if (!keystr) |
294 | fatalbox("Out of memory"); |
295 | rsastr_fmt(keystr, &hostkey); |
296 | verify_ssh_host_key(savedhost, keystr); |
297 | free(keystr); |
298 | } |
07d9aa13 |
299 | |
300 | for (i=0; i<32; i++) { |
301 | rsabuf[i] = session_key[i]; |
302 | if (i < 16) |
303 | rsabuf[i] ^= session_id[i]; |
304 | } |
305 | |
306 | if (hostkey.bytes > servkey.bytes) { |
307 | rsaencrypt(rsabuf, 32, &servkey); |
308 | rsaencrypt(rsabuf, servkey.bytes, &hostkey); |
309 | } else { |
310 | rsaencrypt(rsabuf, 32, &hostkey); |
311 | rsaencrypt(rsabuf, hostkey.bytes, &servkey); |
312 | } |
313 | |
314 | cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH : |
315 | SSH_CIPHER_3DES; |
316 | if ((supported_ciphers_mask & (1 << cipher_type)) == 0) { |
317 | fprintf(stderr, "Selected cipher not supported, falling back to 3DES\n"); |
318 | cipher_type = SSH_CIPHER_3DES; |
319 | } |
320 | |
321 | s_wrpkt_start(SSH_CMSG_SESSION_KEY, len+15); |
322 | pktout.body[0] = cipher_type; |
323 | memcpy(pktout.body+1, cookie, 8); |
324 | pktout.body[9] = (len*8) >> 8; |
325 | pktout.body[10] = (len*8) & 0xFF; |
326 | memcpy(pktout.body+11, rsabuf, len); |
327 | pktout.body[len+11] = pktout.body[len+12] = 0; /* protocol flags */ |
328 | pktout.body[len+13] = pktout.body[len+14] = 0; |
329 | s_wrpkt(); |
330 | |
331 | free(rsabuf); |
332 | |
333 | cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish : |
334 | &ssh_3des; |
335 | cipher->sesskey(session_key); |
336 | |
337 | get_packet(); |
338 | |
339 | if (pktin.type != SSH_SMSG_SUCCESS) |
340 | fatalbox("Encryption not successfully enabled"); |
341 | |
342 | if (verbose) |
343 | fprintf(stderr, "Logging in as \"%s\".\n", username); |
344 | s_wrpkt_start(SSH_CMSG_USER, 4+strlen(username)); |
345 | pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; |
346 | pktout.body[3] = strlen(username); |
347 | memcpy(pktout.body+4, username, strlen(username)); |
348 | s_wrpkt(); |
349 | |
350 | get_packet(); |
351 | |
352 | while (pktin.type == SSH_SMSG_FAILURE) { |
353 | char password[100]; |
354 | char prompt[200]; |
355 | sprintf(prompt, "%s@%s's password: ", username, savedhost); |
356 | ssh_get_password(prompt, password, 100); |
357 | s_wrpkt_start(SSH_CMSG_AUTH_PASSWORD, 4+strlen(password)); |
358 | pktout.body[0] = pktout.body[1] = pktout.body[2] = 0; |
359 | pktout.body[3] = strlen(password); |
360 | memcpy(pktout.body+4, password, strlen(password)); |
361 | s_wrpkt(); |
362 | memset(password, 0, strlen(password)); |
363 | get_packet(); |
364 | if (pktin.type == SSH_SMSG_FAILURE) { |
365 | fprintf(stderr, "Access denied\n"); |
366 | } else if (pktin.type != SSH_SMSG_SUCCESS) { |
367 | fatalbox("Strange packet received, type %d", pktin.type); |
368 | } |
369 | } |
370 | |
371 | /* Execute command */ |
372 | if (verbose) |
373 | fprintf(stderr, "Sending command: %s\n", cmd); |
374 | i = strlen(cmd); |
375 | s_wrpkt_start(SSH_CMSG_EXEC_CMD, 4+i); |
376 | PUT_32BIT(pktout.body, i); |
377 | memcpy(pktout.body+4, cmd, i); |
378 | s_wrpkt(); |
379 | } |
380 | |
381 | |
382 | /* |
383 | * Receive a block of data over the SSH link. Block until |
384 | * all data is available. Return nr of bytes read (0 if lost connection). |
385 | */ |
386 | int ssh_recv(unsigned char *buf, int len) |
387 | { |
388 | static int pending_input_len = 0; |
389 | static unsigned char *pending_input_ptr; |
390 | int to_read = len; |
391 | |
392 | if (pending_input_len >= to_read) { |
393 | memcpy(buf, pending_input_ptr, to_read); |
394 | pending_input_ptr += to_read; |
395 | pending_input_len -= to_read; |
396 | return len; |
397 | } |
398 | |
399 | if (pending_input_len > 0) { |
400 | memcpy(buf, pending_input_ptr, pending_input_len); |
401 | buf += pending_input_len; |
402 | to_read -= pending_input_len; |
403 | pending_input_len = 0; |
404 | } |
405 | |
406 | if (s == INVALID_SOCKET) |
407 | return 0; |
408 | while (to_read > 0) { |
409 | get_packet(); |
410 | if (s == INVALID_SOCKET) |
411 | return 0; |
412 | if (pktin.type == SSH_SMSG_STDOUT_DATA) { |
413 | int plen = GET_32BIT(pktin.body); |
414 | if (plen <= to_read) { |
415 | memcpy(buf, pktin.body + 4, plen); |
416 | buf += plen; |
417 | to_read -= plen; |
418 | } else { |
419 | memcpy(buf, pktin.body + 4, to_read); |
420 | pending_input_len = plen - to_read; |
421 | pending_input_ptr = pktin.body + 4 + to_read; |
422 | to_read = 0; |
423 | } |
424 | } else if (pktin.type == SSH_SMSG_STDERR_DATA) { |
425 | int plen = GET_32BIT(pktin.body); |
426 | fwrite(pktin.body + 4, plen, 1, stderr); |
427 | } else if (pktin.type == SSH_MSG_DISCONNECT) { |
428 | } else if (pktin.type == SSH_SMSG_SUCCESS || |
429 | pktin.type == SSH_SMSG_FAILURE) { |
430 | } else if (pktin.type == SSH_SMSG_EXIT_STATUS) { |
431 | if (verbose) |
432 | fprintf(stderr, "Remote exit status %d\n", |
433 | GET_32BIT(pktin.body)); |
434 | s_wrpkt_start(SSH_CMSG_EXIT_CONFIRMATION, 0); |
435 | s_wrpkt(); |
436 | if (verbose) |
437 | fprintf(stderr, "Closing connection\n"); |
438 | closesocket(s); |
439 | s = INVALID_SOCKET; |
440 | } |
441 | } |
442 | |
443 | return len; |
444 | } |
445 | |
446 | |
447 | /* |
448 | * Send a block of data over the SSH link. |
449 | * Block until all data is sent. |
450 | */ |
451 | void ssh_send(unsigned char *buf, int len) |
452 | { |
453 | if (s == INVALID_SOCKET) |
454 | return; |
455 | s_wrpkt_start(SSH_CMSG_STDIN_DATA, 4 + len); |
456 | PUT_32BIT(pktout.body, len); |
457 | memcpy(pktout.body + 4, buf, len); |
458 | s_wrpkt(); |
459 | } |
460 | |
461 | |
462 | /* |
463 | * Send an EOF notification to the server. |
464 | */ |
465 | void ssh_send_eof(void) |
466 | { |
467 | if (s == INVALID_SOCKET) |
468 | return; |
469 | s_wrpkt_start(SSH_CMSG_EOF, 0); |
470 | s_wrpkt(); |
471 | } |
472 | |
473 | |
474 | /* |
475 | * Set up the connection, login on the remote host and |
476 | * start execution of a command. |
477 | * |
478 | * Returns an error message, or NULL on success. |
479 | * |
480 | * Also places the canonical host name into `realhost'. |
481 | */ |
482 | char *ssh_init(char *host, int port, char *cmd, char **realhost) { |
483 | SOCKADDR_IN addr; |
484 | struct hostent *h; |
485 | unsigned long a; |
486 | #ifdef FWHACK |
487 | char *FWhost; |
488 | int FWport; |
489 | #endif |
490 | |
491 | savedhost = malloc(1+strlen(host)); |
492 | if (!savedhost) |
493 | fatalbox("Out of memory"); |
494 | strcpy(savedhost, host); |
495 | |
496 | #ifdef FWHACK |
497 | FWhost = host; |
498 | FWport = port; |
499 | host = FWSTR; |
500 | port = 23; |
501 | #endif |
502 | |
503 | /* |
504 | * Try to find host. |
505 | */ |
506 | if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) { |
507 | if ( (h = gethostbyname(host)) == NULL) |
508 | switch (WSAGetLastError()) { |
509 | case WSAENETDOWN: return "Network is down"; |
510 | case WSAHOST_NOT_FOUND: case WSANO_DATA: |
511 | return "Host does not exist"; |
512 | case WSATRY_AGAIN: return "Host not found"; |
513 | default: return "gethostbyname: unknown error"; |
514 | } |
515 | memcpy (&a, h->h_addr, sizeof(a)); |
516 | *realhost = h->h_name; |
517 | } else |
518 | *realhost = host; |
519 | #ifdef FWHACK |
520 | *realhost = FWhost; |
521 | #endif |
522 | a = ntohl(a); |
523 | |
524 | if (port < 0) |
525 | port = 22; /* default ssh port */ |
526 | |
527 | /* |
528 | * Open socket. |
529 | */ |
530 | s = socket(AF_INET, SOCK_STREAM, 0); |
531 | if (s == INVALID_SOCKET) |
532 | switch (WSAGetLastError()) { |
533 | case WSAENETDOWN: return "Network is down"; |
534 | case WSAEAFNOSUPPORT: return "TCP/IP support not present"; |
535 | default: return "socket(): unknown error"; |
536 | } |
537 | |
538 | /* |
539 | * Bind to local address. |
540 | */ |
541 | addr.sin_family = AF_INET; |
542 | addr.sin_addr.s_addr = htonl(INADDR_ANY); |
543 | addr.sin_port = htons(0); |
544 | if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR) |
545 | switch (WSAGetLastError()) { |
546 | case WSAENETDOWN: return "Network is down"; |
547 | default: return "bind(): unknown error"; |
548 | } |
549 | |
550 | /* |
551 | * Connect to remote address. |
552 | */ |
553 | addr.sin_addr.s_addr = htonl(a); |
554 | addr.sin_port = htons((short)port); |
555 | if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR) |
556 | switch (WSAGetLastError()) { |
557 | case WSAENETDOWN: return "Network is down"; |
558 | case WSAECONNREFUSED: return "Connection refused"; |
559 | case WSAENETUNREACH: return "Network is unreachable"; |
560 | case WSAEHOSTUNREACH: return "No route to host"; |
561 | default: return "connect(): unknown error"; |
562 | } |
563 | |
564 | #ifdef FWHACK |
565 | send(s, "connect ", 8, 0); |
566 | send(s, FWhost, strlen(FWhost), 0); |
567 | { |
568 | char buf[20]; |
569 | sprintf(buf, " %d\n", FWport); |
570 | send (s, buf, strlen(buf), 0); |
571 | } |
572 | #endif |
573 | |
574 | random_init(); |
575 | |
576 | if (!do_ssh_init()) |
577 | return "Protocol initialisation error"; |
578 | |
579 | ssh_login(cfg.username, cmd); |
580 | |
581 | return NULL; |
582 | } |
583 | |
584 | /* end */ |