Annotation of src/usr.bin/ssh/packet.c, Revision 1.31
1.1 deraadt 1: /*
1.29 markus 2: *
1.15 deraadt 3: * packet.c
1.29 markus 4: *
1.15 deraadt 5: * Author: Tatu Ylonen <ylo@cs.hut.fi>
1.29 markus 6: *
1.15 deraadt 7: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: * All rights reserved
1.29 markus 9: *
1.15 deraadt 10: * Created: Sat Mar 18 02:40:40 1995 ylo
1.29 markus 11: *
1.15 deraadt 12: * This file contains code implementing the packet protocol and communication
13: * with the other side. This same code is used both on client and server side.
1.25 markus 14: *
15: * SSH2 packet format added by Markus Friedl.
16: *
1.15 deraadt 17: */
1.1 deraadt 18:
19: #include "includes.h"
1.31 ! markus 20: RCSID("$Id: packet.c,v 1.30 2000/04/30 09:12:07 markus Exp $");
1.1 deraadt 21:
22: #include "xmalloc.h"
23: #include "buffer.h"
24: #include "packet.h"
25: #include "bufaux.h"
26: #include "ssh.h"
27: #include "crc32.h"
28: #include "cipher.h"
29: #include "getput.h"
30:
31: #include "compress.h"
1.9 dugsong 32: #include "deattack.h"
1.23 markus 33: #include "channels.h"
1.1 deraadt 34:
1.25 markus 35: #include "compat.h"
36: #include "ssh2.h"
37:
1.27 markus 38: #include <openssl/bn.h>
39: #include <openssl/dh.h>
40: #include <openssl/hmac.h>
1.25 markus 41: #include "buffer.h"
42: #include "kex.h"
43: #include "hmac.h"
44:
45: #ifdef PACKET_DEBUG
46: #define DBG(x) x
47: #else
48: #define DBG(x)
49: #endif
50:
1.16 markus 51: /*
52: * This variable contains the file descriptors used for communicating with
53: * the other side. connection_in is used for reading; connection_out for
54: * writing. These can be the same descriptor, in which case it is assumed to
55: * be a socket.
56: */
1.1 deraadt 57: static int connection_in = -1;
58: static int connection_out = -1;
59:
1.16 markus 60: /*
61: * Cipher type. This value is only used to determine whether to pad the
62: * packets with zeroes or random data.
63: */
1.1 deraadt 64: static int cipher_type = SSH_CIPHER_NONE;
65:
66: /* Protocol flags for the remote side. */
67: static unsigned int remote_protocol_flags = 0;
68:
69: /* Encryption context for receiving data. This is only used for decryption. */
70: static CipherContext receive_context;
1.14 markus 71:
72: /* Encryption context for sending data. This is only used for encryption. */
1.1 deraadt 73: static CipherContext send_context;
74:
75: /* Buffer for raw input data from the socket. */
76: static Buffer input;
77:
78: /* Buffer for raw output data going to the socket. */
79: static Buffer output;
80:
81: /* Buffer for the partial outgoing packet being constructed. */
82: static Buffer outgoing_packet;
83:
84: /* Buffer for the incoming packet currently being processed. */
85: static Buffer incoming_packet;
86:
87: /* Scratch buffer for packet compression/decompression. */
88: static Buffer compression_buffer;
89:
90: /* Flag indicating whether packet compression/decompression is enabled. */
91: static int packet_compression = 0;
92:
1.12 markus 93: /* default maximum packet size */
94: int max_packet_size = 32768;
95:
1.1 deraadt 96: /* Flag indicating whether this module has been initialized. */
97: static int initialized = 0;
98:
99: /* Set to true if the connection is interactive. */
100: static int interactive_mode = 0;
101:
1.25 markus 102: /* True if SSH2 packet format is used */
103: int use_ssh2_packet_format = 0;
104:
105: /* Session key information for Encryption and MAC */
106: Kex *kex = NULL;
107:
108: void
109: packet_set_kex(Kex *k)
110: {
111: if( k->mac[MODE_IN ].key == NULL ||
112: k->enc[MODE_IN ].key == NULL ||
113: k->enc[MODE_IN ].iv == NULL ||
114: k->mac[MODE_OUT].key == NULL ||
115: k->enc[MODE_OUT].key == NULL ||
116: k->enc[MODE_OUT].iv == NULL)
117: fatal("bad KEX");
118: kex = k;
119: }
120: void
121: clear_enc_keys(Enc *enc, int len)
122: {
123: memset(enc->iv, 0, len);
124: memset(enc->key, 0, len);
125: xfree(enc->iv);
126: xfree(enc->key);
127: enc->iv = NULL;
128: enc->key = NULL;
129: }
130: void
131: packet_set_ssh2_format(void)
132: {
1.31 ! markus 133: DBG(debug("use_ssh2_packet_format"));
1.25 markus 134: use_ssh2_packet_format = 1;
135: }
136:
1.16 markus 137: /*
138: * Sets the descriptors used for communication. Disables encryption until
139: * packet_set_encryption_key is called.
140: */
1.2 provos 141: void
142: packet_set_connection(int fd_in, int fd_out)
1.1 deraadt 143: {
1.14 markus 144: connection_in = fd_in;
145: connection_out = fd_out;
146: cipher_type = SSH_CIPHER_NONE;
1.26 markus 147: cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *) "", 0);
148: cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *) "", 0);
1.14 markus 149: if (!initialized) {
150: initialized = 1;
151: buffer_init(&input);
152: buffer_init(&output);
153: buffer_init(&outgoing_packet);
154: buffer_init(&incoming_packet);
155: }
156: /* Kludge: arrange the close function to be called from fatal(). */
157: fatal_add_cleanup((void (*) (void *)) packet_close, NULL);
1.1 deraadt 158: }
159:
1.19 markus 160: /* Returns 1 if remote host is connected via socket, 0 if not. */
161:
162: int
163: packet_connection_is_on_socket()
164: {
165: struct sockaddr_storage from, to;
166: socklen_t fromlen, tolen;
167:
168: /* filedescriptors in and out are the same, so it's a socket */
169: if (connection_in == connection_out)
170: return 1;
171: fromlen = sizeof(from);
172: memset(&from, 0, sizeof(from));
1.20 markus 173: if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
1.19 markus 174: return 0;
175: tolen = sizeof(to);
176: memset(&to, 0, sizeof(to));
1.20 markus 177: if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
1.19 markus 178: return 0;
179: if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
180: return 0;
181: if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
182: return 0;
183: return 1;
184: }
185:
186: /* returns 1 if connection is via ipv4 */
187:
188: int
189: packet_connection_is_ipv4()
190: {
191: struct sockaddr_storage to;
1.21 deraadt 192: socklen_t tolen = sizeof(to);
1.19 markus 193:
194: memset(&to, 0, sizeof(to));
195: if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
196: return 0;
197: if (to.ss_family != AF_INET)
198: return 0;
199: return 1;
200: }
201:
1.1 deraadt 202: /* Sets the connection into non-blocking mode. */
203:
1.2 provos 204: void
205: packet_set_nonblocking()
1.1 deraadt 206: {
1.14 markus 207: /* Set the socket into non-blocking mode. */
208: if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0)
209: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
210:
211: if (connection_out != connection_in) {
212: if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0)
213: error("fcntl O_NONBLOCK: %.100s", strerror(errno));
214: }
1.1 deraadt 215: }
216:
217: /* Returns the socket used for reading. */
218:
1.2 provos 219: int
220: packet_get_connection_in()
1.1 deraadt 221: {
1.14 markus 222: return connection_in;
1.1 deraadt 223: }
224:
225: /* Returns the descriptor used for writing. */
226:
1.2 provos 227: int
228: packet_get_connection_out()
1.1 deraadt 229: {
1.14 markus 230: return connection_out;
1.1 deraadt 231: }
232:
233: /* Closes the connection and clears and frees internal data structures. */
234:
1.2 provos 235: void
236: packet_close()
1.1 deraadt 237: {
1.14 markus 238: if (!initialized)
239: return;
240: initialized = 0;
241: if (connection_in == connection_out) {
242: shutdown(connection_out, SHUT_RDWR);
243: close(connection_out);
244: } else {
245: close(connection_in);
246: close(connection_out);
247: }
248: buffer_free(&input);
249: buffer_free(&output);
250: buffer_free(&outgoing_packet);
251: buffer_free(&incoming_packet);
252: if (packet_compression) {
253: buffer_free(&compression_buffer);
254: buffer_compress_uninit();
255: }
1.1 deraadt 256: }
257:
258: /* Sets remote side protocol flags. */
259:
1.2 provos 260: void
261: packet_set_protocol_flags(unsigned int protocol_flags)
1.1 deraadt 262: {
1.14 markus 263: remote_protocol_flags = protocol_flags;
264: channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0);
1.1 deraadt 265: }
266:
267: /* Returns the remote protocol flags set earlier by the above function. */
268:
1.2 provos 269: unsigned int
270: packet_get_protocol_flags()
1.1 deraadt 271: {
1.14 markus 272: return remote_protocol_flags;
1.1 deraadt 273: }
274:
1.16 markus 275: /*
276: * Starts packet compression from the next packet on in both directions.
277: * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
278: */
1.1 deraadt 279:
1.25 markus 280: /*** XXXXX todo: kex means re-init */
1.2 provos 281: void
282: packet_start_compression(int level)
1.1 deraadt 283: {
1.14 markus 284: if (packet_compression)
285: fatal("Compression already enabled.");
286: packet_compression = 1;
287: buffer_init(&compression_buffer);
288: buffer_compress_init(level);
1.1 deraadt 289: }
290:
1.16 markus 291: /*
292: * Encrypts the given number of bytes, copying from src to dest. bytes is
293: * known to be a multiple of 8.
294: */
1.1 deraadt 295:
1.2 provos 296: void
1.14 markus 297: packet_encrypt(CipherContext * cc, void *dest, void *src,
1.25 markus 298: unsigned int bytes)
1.1 deraadt 299: {
1.14 markus 300: cipher_encrypt(cc, dest, src, bytes);
1.1 deraadt 301: }
302:
1.16 markus 303: /*
304: * Decrypts the given number of bytes, copying from src to dest. bytes is
305: * known to be a multiple of 8.
306: */
1.1 deraadt 307:
1.2 provos 308: void
1.14 markus 309: packet_decrypt(CipherContext * cc, void *dest, void *src,
1.25 markus 310: unsigned int bytes)
1.1 deraadt 311: {
1.14 markus 312: int i;
313:
314: if ((bytes % 8) != 0)
315: fatal("packet_decrypt: bad ciphertext length %d", bytes);
316:
1.16 markus 317: /*
318: * Cryptographic attack detector for ssh - Modifications for packet.c
319: * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com)
320: */
1.14 markus 321:
1.25 markus 322: if (cc->type == SSH_CIPHER_NONE || compat20) {
1.14 markus 323: i = DEATTACK_OK;
1.25 markus 324: } else {
1.14 markus 325: i = detect_attack(src, bytes, NULL);
326: }
327: if (i == DEATTACK_DETECTED)
328: packet_disconnect("crc32 compensation attack: network attack detected");
329:
330: cipher_decrypt(cc, dest, src, bytes);
1.1 deraadt 331: }
332:
1.16 markus 333: /*
334: * Causes any further packets to be encrypted using the given key. The same
335: * key is used for both sending and reception. However, both directions are
336: * encrypted independently of each other.
337: */
1.1 deraadt 338:
1.2 provos 339: void
340: packet_set_encryption_key(const unsigned char *key, unsigned int keylen,
1.25 markus 341: int cipher)
1.1 deraadt 342: {
1.25 markus 343: if (keylen < 20)
344: fatal("keylen too small: %d", keylen);
345:
1.14 markus 346: /* All other ciphers use the same key in both directions for now. */
1.26 markus 347: cipher_set_key(&receive_context, cipher, key, keylen);
348: cipher_set_key(&send_context, cipher, key, keylen);
1.1 deraadt 349: }
350:
351: /* Starts constructing a packet to send. */
352:
1.2 provos 353: void
1.25 markus 354: packet_start1(int type)
1.1 deraadt 355: {
1.14 markus 356: char buf[9];
1.1 deraadt 357:
1.14 markus 358: buffer_clear(&outgoing_packet);
359: memset(buf, 0, 8);
360: buf[8] = type;
361: buffer_append(&outgoing_packet, buf, 9);
1.1 deraadt 362: }
363:
1.25 markus 364: void
365: packet_start2(int type)
366: {
367: char buf[4+1+1];
368:
369: buffer_clear(&outgoing_packet);
370: memset(buf, 0, sizeof buf);
371: /* buf[0..3] = payload_len; */
372: /* buf[4] = pad_len; */
373: buf[5] = type & 0xff;
374: buffer_append(&outgoing_packet, buf, sizeof buf);
375: }
376:
377: void
378: packet_start(int type)
379: {
380: DBG(debug("packet_start[%d]",type));
381: if (use_ssh2_packet_format)
382: packet_start2(type);
383: else
384: packet_start1(type);
385: }
386:
1.1 deraadt 387: /* Appends a character to the packet data. */
388:
1.2 provos 389: void
390: packet_put_char(int value)
1.1 deraadt 391: {
1.14 markus 392: char ch = value;
393: buffer_append(&outgoing_packet, &ch, 1);
1.1 deraadt 394: }
395:
396: /* Appends an integer to the packet data. */
397:
1.2 provos 398: void
399: packet_put_int(unsigned int value)
1.1 deraadt 400: {
1.14 markus 401: buffer_put_int(&outgoing_packet, value);
1.1 deraadt 402: }
403:
404: /* Appends a string to packet data. */
405:
1.2 provos 406: void
407: packet_put_string(const char *buf, unsigned int len)
1.1 deraadt 408: {
1.14 markus 409: buffer_put_string(&outgoing_packet, buf, len);
1.1 deraadt 410: }
1.24 markus 411: void
412: packet_put_cstring(const char *str)
413: {
414: buffer_put_string(&outgoing_packet, str, strlen(str));
415: }
416:
417: void
418: packet_put_raw(const char *buf, unsigned int len)
419: {
420: buffer_append(&outgoing_packet, buf, len);
421: }
422:
1.1 deraadt 423:
424: /* Appends an arbitrary precision integer to packet data. */
425:
1.2 provos 426: void
1.14 markus 427: packet_put_bignum(BIGNUM * value)
1.1 deraadt 428: {
1.14 markus 429: buffer_put_bignum(&outgoing_packet, value);
1.1 deraadt 430: }
1.24 markus 431: void
432: packet_put_bignum2(BIGNUM * value)
433: {
434: buffer_put_bignum2(&outgoing_packet, value);
435: }
1.1 deraadt 436:
1.16 markus 437: /*
438: * Finalizes and sends the packet. If the encryption key has been set,
439: * encrypts the packet before sending.
440: */
1.14 markus 441:
1.2 provos 442: void
1.25 markus 443: packet_send1()
1.1 deraadt 444: {
1.14 markus 445: char buf[8], *cp;
446: int i, padding, len;
447: unsigned int checksum;
448: u_int32_t rand = 0;
449:
1.16 markus 450: /*
451: * If using packet compression, compress the payload of the outgoing
452: * packet.
453: */
1.14 markus 454: if (packet_compression) {
455: buffer_clear(&compression_buffer);
456: /* Skip padding. */
457: buffer_consume(&outgoing_packet, 8);
458: /* padding */
459: buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
460: buffer_compress(&outgoing_packet, &compression_buffer);
461: buffer_clear(&outgoing_packet);
462: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
463: buffer_len(&compression_buffer));
464: }
465: /* Compute packet length without padding (add checksum, remove padding). */
466: len = buffer_len(&outgoing_packet) + 4 - 8;
467:
468: /* Insert padding. */
469: padding = 8 - len % 8;
470: if (cipher_type != SSH_CIPHER_NONE) {
471: cp = buffer_ptr(&outgoing_packet);
472: for (i = 0; i < padding; i++) {
473: if (i % 4 == 0)
474: rand = arc4random();
475: cp[7 - i] = rand & 0xff;
476: rand >>= 8;
477: }
478: }
479: buffer_consume(&outgoing_packet, 8 - padding);
480:
481: /* Add check bytes. */
482: checksum = crc32((unsigned char *) buffer_ptr(&outgoing_packet),
483: buffer_len(&outgoing_packet));
484: PUT_32BIT(buf, checksum);
485: buffer_append(&outgoing_packet, buf, 4);
1.1 deraadt 486:
487: #ifdef PACKET_DEBUG
1.14 markus 488: fprintf(stderr, "packet_send plain: ");
489: buffer_dump(&outgoing_packet);
1.1 deraadt 490: #endif
491:
1.14 markus 492: /* Append to output. */
493: PUT_32BIT(buf, len);
494: buffer_append(&output, buf, 4);
495: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
496: packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
497: buffer_len(&outgoing_packet));
498:
1.1 deraadt 499: #ifdef PACKET_DEBUG
1.14 markus 500: fprintf(stderr, "encrypted: ");
501: buffer_dump(&output);
1.1 deraadt 502: #endif
503:
1.14 markus 504: buffer_clear(&outgoing_packet);
1.1 deraadt 505:
1.16 markus 506: /*
507: * Note that the packet is now only buffered in output. It won\'t be
508: * actually sent until packet_write_wait or packet_write_poll is
509: * called.
510: */
1.1 deraadt 511: }
512:
1.16 markus 513: /*
1.25 markus 514: * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
515: */
516: void
517: packet_send2()
518: {
519: unsigned char *macbuf = NULL;
520: char *cp;
521: unsigned int packet_length = 0;
522: unsigned int i, padlen, len;
523: u_int32_t rand = 0;
1.29 markus 524: static unsigned int seqnr = 0;
1.25 markus 525: int type;
526: Enc *enc = NULL;
527: Mac *mac = NULL;
528: Comp *comp = NULL;
529: int block_size;
530:
531: if (kex != NULL) {
532: enc = &kex->enc[MODE_OUT];
533: mac = &kex->mac[MODE_OUT];
534: comp = &kex->comp[MODE_OUT];
535: }
536: block_size = enc ? enc->block_size : 8;
537:
538: cp = buffer_ptr(&outgoing_packet);
539: type = cp[5] & 0xff;
540:
541: #ifdef PACKET_DEBUG
542: fprintf(stderr, "plain: ");
543: buffer_dump(&outgoing_packet);
544: #endif
545:
546: if (comp && comp->enabled) {
547: len = buffer_len(&outgoing_packet);
548: /* skip header, compress only payload */
549: buffer_consume(&outgoing_packet, 5);
550: buffer_clear(&compression_buffer);
551: buffer_compress(&outgoing_packet, &compression_buffer);
552: buffer_clear(&outgoing_packet);
553: buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
554: buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
555: buffer_len(&compression_buffer));
556: DBG(debug("compression: raw %d compressed %d", len,
557: buffer_len(&outgoing_packet)));
558: }
559:
560: /* sizeof (packet_len + pad_len + payload) */
561: len = buffer_len(&outgoing_packet);
562:
563: /*
564: * calc size of padding, alloc space, get random data,
565: * minimum padding is 4 bytes
566: */
567: padlen = block_size - (len % block_size);
568: if (padlen < 4)
569: padlen += block_size;
570: buffer_append_space(&outgoing_packet, &cp, padlen);
571: if (enc && enc->type != SSH_CIPHER_NONE) {
572: for (i = 0; i < padlen; i++) {
573: if (i % 4 == 0)
574: rand = arc4random();
575: cp[i] = rand & 0xff;
576: rand <<= 8;
577: }
578: }
579: /* packet_length includes payload, padding and padding length field */
580: packet_length = buffer_len(&outgoing_packet) - 4;
581: cp = buffer_ptr(&outgoing_packet);
582: PUT_32BIT(cp, packet_length);
583: cp[4] = padlen & 0xff;
584: DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
585:
586: /* compute MAC over seqnr and packet(length fields, payload, padding) */
587: if (mac && mac->enabled) {
588: macbuf = hmac( mac->md, seqnr,
589: (unsigned char *) buffer_ptr(&outgoing_packet),
590: buffer_len(&outgoing_packet),
591: mac->key, mac->key_len
592: );
593: DBG(debug("done calc HMAC out #%d", seqnr));
594: }
595: /* encrypt packet and append to output buffer. */
596: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
597: packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
598: buffer_len(&outgoing_packet));
599: /* append unencrypted MAC */
600: if (mac && mac->enabled)
601: buffer_append(&output, (char *)macbuf, mac->mac_len);
602: #ifdef PACKET_DEBUG
603: fprintf(stderr, "encrypted: ");
604: buffer_dump(&output);
605: #endif
1.29 markus 606: /* increment sequence number for outgoing packets */
607: if (++seqnr == 0)
608: log("outgoing seqnr wraps around");
1.25 markus 609: buffer_clear(&outgoing_packet);
610:
611: if (type == SSH2_MSG_NEWKEYS) {
612: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
613: fatal("packet_send2: no KEX");
614: if (mac->md != NULL)
615: mac->enabled = 1;
1.31 ! markus 616: DBG(debug("cipher_set_key_iv send_context"));
1.25 markus 617: cipher_set_key_iv(&send_context, enc->type,
618: enc->key, enc->key_len,
619: enc->iv, enc->iv_len);
620: clear_enc_keys(enc, kex->we_need);
621: if (comp->type != 0 && comp->enabled == 0) {
622: comp->enabled = 1;
623: if (! packet_compression)
624: packet_start_compression(6);
625: }
626: }
627: }
628:
629: void
630: packet_send()
631: {
632: if (use_ssh2_packet_format)
633: packet_send2();
634: else
635: packet_send1();
636: DBG(debug("packet_send done"));
637: }
638:
639: /*
1.16 markus 640: * Waits until a packet has been received, and returns its type. Note that
641: * no other data is processed until this returns, so this function should not
642: * be used during the interactive session.
643: */
1.1 deraadt 644:
1.2 provos 645: int
646: packet_read(int *payload_len_ptr)
1.1 deraadt 647: {
1.14 markus 648: int type, len;
649: fd_set set;
650: char buf[8192];
1.25 markus 651: DBG(debug("packet_read()"));
1.14 markus 652:
653: /* Since we are blocking, ensure that all written packets have been sent. */
654: packet_write_wait();
655:
656: /* Stay in the loop until we have received a complete packet. */
657: for (;;) {
658: /* Try to read a packet from the buffer. */
659: type = packet_read_poll(payload_len_ptr);
660: if (type == SSH_SMSG_SUCCESS
661: || type == SSH_SMSG_FAILURE
662: || type == SSH_CMSG_EOF
663: || type == SSH_CMSG_EXIT_CONFIRMATION)
664: packet_integrity_check(*payload_len_ptr, 0, type);
665: /* If we got a packet, return it. */
666: if (type != SSH_MSG_NONE)
667: return type;
1.16 markus 668: /*
669: * Otherwise, wait for some data to arrive, add it to the
670: * buffer, and try again.
671: */
1.14 markus 672: FD_ZERO(&set);
673: FD_SET(connection_in, &set);
1.16 markus 674:
1.14 markus 675: /* Wait for some data to arrive. */
676: select(connection_in + 1, &set, NULL, NULL, NULL);
1.16 markus 677:
1.14 markus 678: /* Read data from the socket. */
679: len = read(connection_in, buf, sizeof(buf));
1.18 markus 680: if (len == 0) {
681: log("Connection closed by %.200s", get_remote_ipaddr());
682: fatal_cleanup();
683: }
1.14 markus 684: if (len < 0)
685: fatal("Read from socket failed: %.100s", strerror(errno));
686: /* Append it to the buffer. */
687: packet_process_incoming(buf, len);
688: }
689: /* NOTREACHED */
1.1 deraadt 690: }
691:
1.16 markus 692: /*
693: * Waits until a packet has been received, verifies that its type matches
694: * that given, and gives a fatal error and exits if there is a mismatch.
695: */
1.1 deraadt 696:
1.2 provos 697: void
698: packet_read_expect(int *payload_len_ptr, int expected_type)
1.1 deraadt 699: {
1.14 markus 700: int type;
1.1 deraadt 701:
1.14 markus 702: type = packet_read(payload_len_ptr);
703: if (type != expected_type)
704: packet_disconnect("Protocol error: expected packet type %d, got %d",
1.25 markus 705: expected_type, type);
1.1 deraadt 706: }
707:
708: /* Checks if a full packet is available in the data received so far via
1.14 markus 709: * packet_process_incoming. If so, reads the packet; otherwise returns
710: * SSH_MSG_NONE. This does not wait for data from the connection.
711: *
712: * SSH_MSG_DISCONNECT is handled specially here. Also,
713: * SSH_MSG_IGNORE messages are skipped by this function and are never returned
714: * to higher levels.
715: *
716: * The returned payload_len does include space consumed by:
717: * Packet length
718: * Padding
719: * Packet type
720: * Check bytes
721: */
1.1 deraadt 722:
1.2 provos 723: int
1.25 markus 724: packet_read_poll1(int *payload_len_ptr)
1.1 deraadt 725: {
1.14 markus 726: unsigned int len, padded_len;
727: unsigned char *ucp;
1.25 markus 728: char buf[8], *cp;
1.14 markus 729: unsigned int checksum, stored_checksum;
730:
731: /* Check if input size is less than minimum packet size. */
732: if (buffer_len(&input) < 4 + 8)
733: return SSH_MSG_NONE;
734: /* Get length of incoming packet. */
735: ucp = (unsigned char *) buffer_ptr(&input);
736: len = GET_32BIT(ucp);
737: if (len < 1 + 2 + 2 || len > 256 * 1024)
738: packet_disconnect("Bad packet length %d.", len);
739: padded_len = (len + 8) & ~7;
740:
741: /* Check if the packet has been entirely received. */
742: if (buffer_len(&input) < 4 + padded_len)
743: return SSH_MSG_NONE;
744:
745: /* The entire packet is in buffer. */
746:
747: /* Consume packet length. */
748: buffer_consume(&input, 4);
749:
750: /* Copy data to incoming_packet. */
751: buffer_clear(&incoming_packet);
752: buffer_append_space(&incoming_packet, &cp, padded_len);
753: packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
754: buffer_consume(&input, padded_len);
1.1 deraadt 755:
756: #ifdef PACKET_DEBUG
1.14 markus 757: fprintf(stderr, "read_poll plain: ");
758: buffer_dump(&incoming_packet);
1.1 deraadt 759: #endif
760:
1.14 markus 761: /* Compute packet checksum. */
762: checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet),
1.25 markus 763: buffer_len(&incoming_packet) - 4);
1.14 markus 764:
765: /* Skip padding. */
766: buffer_consume(&incoming_packet, 8 - len % 8);
767:
768: /* Test check bytes. */
769:
770: if (len != buffer_len(&incoming_packet))
771: packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
1.25 markus 772: len, buffer_len(&incoming_packet));
1.14 markus 773:
774: ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4;
775: stored_checksum = GET_32BIT(ucp);
776: if (checksum != stored_checksum)
777: packet_disconnect("Corrupted check bytes on input.");
778: buffer_consume_end(&incoming_packet, 4);
779:
780: /* If using packet compression, decompress the packet. */
781: if (packet_compression) {
782: buffer_clear(&compression_buffer);
783: buffer_uncompress(&incoming_packet, &compression_buffer);
784: buffer_clear(&incoming_packet);
785: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1.25 markus 786: buffer_len(&compression_buffer));
1.14 markus 787: }
788: /* Get packet type. */
789: buffer_get(&incoming_packet, &buf[0], 1);
790:
791: /* Return length of payload (without type field). */
792: *payload_len_ptr = buffer_len(&incoming_packet);
793:
794: /* Return type. */
795: return (unsigned char) buf[0];
1.1 deraadt 796: }
1.14 markus 797:
1.25 markus 798: int
799: packet_read_poll2(int *payload_len_ptr)
800: {
801: unsigned int padlen, need;
802: unsigned char buf[8], *macbuf;
803: unsigned char *ucp;
804: char *cp;
805: static unsigned int packet_length = 0;
806: static unsigned int seqnr = 0;
807: int type;
808: int maclen, block_size;
809: Enc *enc = NULL;
810: Mac *mac = NULL;
811: Comp *comp = NULL;
812:
813: if (kex != NULL) {
814: enc = &kex->enc[MODE_IN];
815: mac = &kex->mac[MODE_IN];
816: comp = &kex->comp[MODE_IN];
817: }
818: maclen = mac && mac->enabled ? mac->mac_len : 0;
819: block_size = enc ? enc->block_size : 8;
820:
821: if (packet_length == 0) {
822: /*
823: * check if input size is less than the cipher block size,
824: * decrypt first block and extract length of incoming packet
825: */
826: if (buffer_len(&input) < block_size)
827: return SSH_MSG_NONE;
828: buffer_clear(&incoming_packet);
829: buffer_append_space(&incoming_packet, &cp, block_size);
830: packet_decrypt(&receive_context, cp, buffer_ptr(&input),
831: block_size);
832: ucp = (unsigned char *) buffer_ptr(&incoming_packet);
833: packet_length = GET_32BIT(ucp);
834: if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
835: buffer_dump(&incoming_packet);
836: packet_disconnect("Bad packet length %d.", packet_length);
837: }
838: DBG(debug("input: packet len %d", packet_length+4));
839: buffer_consume(&input, block_size);
840: }
841: /* we have a partial packet of block_size bytes */
842: need = 4 + packet_length - block_size;
843: DBG(debug("partial packet %d, need %d, maclen %d", block_size,
844: need, maclen));
845: if (need % block_size != 0)
846: fatal("padding error: need %d block %d mod %d",
847: need, block_size, need % block_size);
848: /*
849: * check if the entire packet has been received and
850: * decrypt into incoming_packet
851: */
852: if (buffer_len(&input) < need + maclen)
853: return SSH_MSG_NONE;
854: #ifdef PACKET_DEBUG
855: fprintf(stderr, "read_poll enc/full: ");
856: buffer_dump(&input);
857: #endif
858: buffer_append_space(&incoming_packet, &cp, need);
859: packet_decrypt(&receive_context, cp, buffer_ptr(&input), need);
860: buffer_consume(&input, need);
861: /*
862: * compute MAC over seqnr and packet,
863: * increment sequence number for incoming packet
864: */
1.29 markus 865: if (mac && mac->enabled) {
1.25 markus 866: macbuf = hmac( mac->md, seqnr,
867: (unsigned char *) buffer_ptr(&incoming_packet),
868: buffer_len(&incoming_packet),
869: mac->key, mac->key_len
870: );
871: if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
872: packet_disconnect("Corrupted HMAC on input.");
873: DBG(debug("HMAC #%d ok", seqnr));
874: buffer_consume(&input, mac->mac_len);
875: }
1.29 markus 876: if (++seqnr == 0)
877: log("incoming seqnr wraps around");
1.25 markus 878:
879: /* get padlen */
880: cp = buffer_ptr(&incoming_packet) + 4;
881: padlen = *cp & 0xff;
882: DBG(debug("input: padlen %d", padlen));
883: if (padlen < 4)
884: packet_disconnect("Corrupted padlen %d on input.", padlen);
885:
886: /* skip packet size + padlen, discard padding */
887: buffer_consume(&incoming_packet, 4 + 1);
888: buffer_consume_end(&incoming_packet, padlen);
889:
890: DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
891: if (comp && comp->enabled) {
892: buffer_clear(&compression_buffer);
893: buffer_uncompress(&incoming_packet, &compression_buffer);
894: buffer_clear(&incoming_packet);
895: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
896: buffer_len(&compression_buffer));
897: DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
898: }
899: /*
900: * get packet type, implies consume.
901: * return length of payload (without type field)
902: */
903: buffer_get(&incoming_packet, (char *)&buf[0], 1);
904: *payload_len_ptr = buffer_len(&incoming_packet);
905:
906: /* reset for next packet */
907: packet_length = 0;
908:
909: /* extract packet type */
910: type = (unsigned char)buf[0];
911:
912: if (type == SSH2_MSG_NEWKEYS) {
913: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
914: fatal("packet_read_poll2: no KEX");
915: if (mac->md != NULL)
916: mac->enabled = 1;
1.31 ! markus 917: DBG(debug("cipher_set_key_iv receive_context"));
1.25 markus 918: cipher_set_key_iv(&receive_context, enc->type,
919: enc->key, enc->key_len,
920: enc->iv, enc->iv_len);
921: clear_enc_keys(enc, kex->we_need);
922: if (comp->type != 0 && comp->enabled == 0) {
923: comp->enabled = 1;
924: if (! packet_compression)
925: packet_start_compression(6);
926: }
927: }
928:
929: #ifdef PACKET_DEBUG
930: fprintf(stderr, "read/plain[%d]:\r\n",type);
931: buffer_dump(&incoming_packet);
932: #endif
933: return (unsigned char)type;
934: }
935:
936: int
937: packet_read_poll(int *payload_len_ptr)
938: {
939: char *msg;
940: for (;;) {
941: int type = use_ssh2_packet_format ?
942: packet_read_poll2(payload_len_ptr):
943: packet_read_poll1(payload_len_ptr);
944:
945: if(compat20) {
946: int reason;
947: if (type != 0)
948: DBG(debug("received packet type %d", type));
949: switch(type) {
950: case SSH2_MSG_IGNORE:
951: break;
952: case SSH2_MSG_DEBUG:
953: packet_get_char();
954: msg = packet_get_string(NULL);
955: debug("Remote: %.900s", msg);
956: xfree(msg);
957: msg = packet_get_string(NULL);
958: xfree(msg);
959: break;
960: case SSH2_MSG_DISCONNECT:
961: reason = packet_get_int();
962: msg = packet_get_string(NULL);
963: log("Received disconnect: %d: %.900s", reason, msg);
964: xfree(msg);
965: fatal_cleanup();
966: break;
967: default:
968: return type;
969: break;
970: }
971: } else {
972: switch(type) {
973: case SSH_MSG_IGNORE:
974: break;
975: case SSH_MSG_DEBUG:
976: msg = packet_get_string(NULL);
977: debug("Remote: %.900s", msg);
978: xfree(msg);
979: break;
980: case SSH_MSG_DISCONNECT:
981: msg = packet_get_string(NULL);
982: log("Received disconnect: %.900s", msg);
983: fatal_cleanup();
984: xfree(msg);
985: break;
986: default:
987: if (type != 0)
988: DBG(debug("received packet type %d", type));
989: return type;
990: break;
991: }
992: }
993: }
994: }
995:
1.16 markus 996: /*
997: * Buffers the given amount of input characters. This is intended to be used
998: * together with packet_read_poll.
999: */
1.1 deraadt 1000:
1.2 provos 1001: void
1002: packet_process_incoming(const char *buf, unsigned int len)
1.1 deraadt 1003: {
1.14 markus 1004: buffer_append(&input, buf, len);
1.1 deraadt 1005: }
1006:
1007: /* Returns a character from the packet. */
1008:
1.2 provos 1009: unsigned int
1010: packet_get_char()
1.1 deraadt 1011: {
1.14 markus 1012: char ch;
1013: buffer_get(&incoming_packet, &ch, 1);
1014: return (unsigned char) ch;
1.1 deraadt 1015: }
1016:
1017: /* Returns an integer from the packet data. */
1018:
1.2 provos 1019: unsigned int
1020: packet_get_int()
1.1 deraadt 1021: {
1.14 markus 1022: return buffer_get_int(&incoming_packet);
1.1 deraadt 1023: }
1024:
1.16 markus 1025: /*
1026: * Returns an arbitrary precision integer from the packet data. The integer
1027: * must have been initialized before this call.
1028: */
1.1 deraadt 1029:
1.2 provos 1030: void
1.14 markus 1031: packet_get_bignum(BIGNUM * value, int *length_ptr)
1.1 deraadt 1032: {
1.14 markus 1033: *length_ptr = buffer_get_bignum(&incoming_packet, value);
1.24 markus 1034: }
1035:
1036: void
1037: packet_get_bignum2(BIGNUM * value, int *length_ptr)
1038: {
1039: *length_ptr = buffer_get_bignum2(&incoming_packet, value);
1040: }
1041:
1042: char *
1043: packet_get_raw(int *length_ptr)
1044: {
1045: int bytes = buffer_len(&incoming_packet);
1046: if (length_ptr != NULL)
1047: *length_ptr = bytes;
1048: return buffer_ptr(&incoming_packet);
1.28 markus 1049: }
1050:
1051: int
1052: packet_remaining(void)
1053: {
1054: return buffer_len(&incoming_packet);
1.1 deraadt 1055: }
1056:
1.16 markus 1057: /*
1058: * Returns a string from the packet data. The string is allocated using
1059: * xmalloc; it is the responsibility of the calling program to free it when
1060: * no longer needed. The length_ptr argument may be NULL, or point to an
1061: * integer into which the length of the string is stored.
1062: */
1.1 deraadt 1063:
1.16 markus 1064: char *
1.14 markus 1065: packet_get_string(unsigned int *length_ptr)
1.1 deraadt 1066: {
1.14 markus 1067: return buffer_get_string(&incoming_packet, length_ptr);
1.1 deraadt 1068: }
1069:
1.16 markus 1070: /*
1071: * Sends a diagnostic message from the server to the client. This message
1072: * can be sent at any time (but not while constructing another message). The
1073: * message is printed immediately, but only if the client is being executed
1074: * in verbose mode. These messages are primarily intended to ease debugging
1075: * authentication problems. The length of the formatted message must not
1076: * exceed 1024 bytes. This will automatically call packet_write_wait.
1077: */
1.1 deraadt 1078:
1.2 provos 1079: void
1.14 markus 1080: packet_send_debug(const char *fmt,...)
1.1 deraadt 1081: {
1.14 markus 1082: char buf[1024];
1083: va_list args;
1084:
1085: va_start(args, fmt);
1086: vsnprintf(buf, sizeof(buf), fmt, args);
1087: va_end(args);
1088:
1.30 markus 1089: if (compat20) {
1090: packet_start(SSH2_MSG_DEBUG);
1091: packet_put_char(0); /* bool: always display */
1092: packet_put_cstring(buf);
1093: packet_put_cstring("");
1094: } else {
1095: packet_start(SSH_MSG_DEBUG);
1096: packet_put_cstring(buf);
1097: }
1.14 markus 1098: packet_send();
1099: packet_write_wait();
1.1 deraadt 1100: }
1101:
1.16 markus 1102: /*
1103: * Logs the error plus constructs and sends a disconnect packet, closes the
1104: * connection, and exits. This function never returns. The error message
1105: * should not contain a newline. The length of the formatted message must
1106: * not exceed 1024 bytes.
1107: */
1.1 deraadt 1108:
1.2 provos 1109: void
1.14 markus 1110: packet_disconnect(const char *fmt,...)
1.1 deraadt 1111: {
1.14 markus 1112: char buf[1024];
1113: va_list args;
1114: static int disconnecting = 0;
1115: if (disconnecting) /* Guard against recursive invocations. */
1116: fatal("packet_disconnect called recursively.");
1117: disconnecting = 1;
1118:
1.16 markus 1119: /*
1120: * Format the message. Note that the caller must make sure the
1121: * message is of limited size.
1122: */
1.14 markus 1123: va_start(args, fmt);
1124: vsnprintf(buf, sizeof(buf), fmt, args);
1125: va_end(args);
1126:
1127: /* Send the disconnect message to the other side, and wait for it to get sent. */
1.25 markus 1128: if (compat20) {
1129: packet_start(SSH2_MSG_DISCONNECT);
1130: packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1131: packet_put_cstring(buf);
1132: packet_put_cstring("");
1133: } else {
1134: packet_start(SSH_MSG_DISCONNECT);
1135: packet_put_string(buf, strlen(buf));
1136: }
1.14 markus 1137: packet_send();
1138: packet_write_wait();
1139:
1140: /* Stop listening for connections. */
1141: channel_stop_listening();
1142:
1143: /* Close the connection. */
1144: packet_close();
1.1 deraadt 1145:
1.14 markus 1146: /* Display the error locally and exit. */
1.17 markus 1147: log("Disconnecting: %.100s", buf);
1148: fatal_cleanup();
1.1 deraadt 1149: }
1150:
1.16 markus 1151: /* Checks if there is any buffered output, and tries to write some of the output. */
1.1 deraadt 1152:
1.2 provos 1153: void
1154: packet_write_poll()
1.1 deraadt 1155: {
1.14 markus 1156: int len = buffer_len(&output);
1157: if (len > 0) {
1158: len = write(connection_out, buffer_ptr(&output), len);
1159: if (len <= 0) {
1160: if (errno == EAGAIN)
1161: return;
1162: else
1163: fatal("Write failed: %.100s", strerror(errno));
1164: }
1165: buffer_consume(&output, len);
1166: }
1.1 deraadt 1167: }
1168:
1.16 markus 1169: /*
1170: * Calls packet_write_poll repeatedly until all pending output data has been
1171: * written.
1172: */
1.1 deraadt 1173:
1.2 provos 1174: void
1175: packet_write_wait()
1.1 deraadt 1176: {
1.14 markus 1177: packet_write_poll();
1178: while (packet_have_data_to_write()) {
1179: fd_set set;
1180: FD_ZERO(&set);
1181: FD_SET(connection_out, &set);
1182: select(connection_out + 1, NULL, &set, NULL, NULL);
1183: packet_write_poll();
1184: }
1.1 deraadt 1185: }
1186:
1187: /* Returns true if there is buffered data to write to the connection. */
1188:
1.2 provos 1189: int
1190: packet_have_data_to_write()
1.1 deraadt 1191: {
1.14 markus 1192: return buffer_len(&output) != 0;
1.1 deraadt 1193: }
1194:
1195: /* Returns true if there is not too much data to write to the connection. */
1196:
1.2 provos 1197: int
1198: packet_not_very_much_data_to_write()
1.1 deraadt 1199: {
1.14 markus 1200: if (interactive_mode)
1201: return buffer_len(&output) < 16384;
1202: else
1203: return buffer_len(&output) < 128 * 1024;
1.1 deraadt 1204: }
1205:
1206: /* Informs that the current session is interactive. Sets IP flags for that. */
1207:
1.2 provos 1208: void
1209: packet_set_interactive(int interactive, int keepalives)
1.1 deraadt 1210: {
1.14 markus 1211: int on = 1;
1.1 deraadt 1212:
1.14 markus 1213: /* Record that we are in interactive mode. */
1214: interactive_mode = interactive;
1.1 deraadt 1215:
1.19 markus 1216: /* Only set socket options if using a socket. */
1217: if (!packet_connection_is_on_socket())
1.14 markus 1218: return;
1219: if (keepalives) {
1220: /* Set keepalives if requested. */
1221: if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on,
1.19 markus 1222: sizeof(on)) < 0)
1.14 markus 1223: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1224: }
1.19 markus 1225: /*
1226: * IPTOS_LOWDELAY, TCP_NODELAY and IPTOS_THROUGHPUT are IPv4 only
1227: */
1228: if (!packet_connection_is_ipv4())
1229: return;
1.14 markus 1230: if (interactive) {
1.16 markus 1231: /*
1232: * Set IP options for an interactive connection. Use
1233: * IPTOS_LOWDELAY and TCP_NODELAY.
1234: */
1.14 markus 1235: int lowdelay = IPTOS_LOWDELAY;
1236: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay,
1.19 markus 1237: sizeof(lowdelay)) < 0)
1.14 markus 1238: error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno));
1239: if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1.19 markus 1240: sizeof(on)) < 0)
1.14 markus 1241: error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1242: } else {
1.16 markus 1243: /*
1244: * Set IP options for a non-interactive connection. Use
1245: * IPTOS_THROUGHPUT.
1246: */
1.14 markus 1247: int throughput = IPTOS_THROUGHPUT;
1248: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1.19 markus 1249: sizeof(throughput)) < 0)
1.14 markus 1250: error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1251: }
1.1 deraadt 1252: }
1253:
1254: /* Returns true if the current connection is interactive. */
1255:
1.2 provos 1256: int
1257: packet_is_interactive()
1.1 deraadt 1258: {
1.14 markus 1259: return interactive_mode;
1.12 markus 1260: }
1261:
1262: int
1263: packet_set_maxsize(int s)
1264: {
1.14 markus 1265: static int called = 0;
1266: if (called) {
1.25 markus 1267: log("packet_set_maxsize: called twice: old %d new %d",
1268: max_packet_size, s);
1.14 markus 1269: return -1;
1270: }
1271: if (s < 4 * 1024 || s > 1024 * 1024) {
1272: log("packet_set_maxsize: bad size %d", s);
1273: return -1;
1274: }
1275: log("packet_set_maxsize: setting to %d", s);
1276: max_packet_size = s;
1277: return s;
1.1 deraadt 1278: }