Annotation of src/usr.bin/ssh/packet.c, Revision 1.32.2.1
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"
1.32.2.1! jason 20: RCSID("$OpenBSD: packet.c,v 1.34 2000/08/19 02:17:12 deraadt 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:
1.32 markus 468: /* Insert padding. Initialized to zero in packet_start1() */
1.14 markus 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. */
1.32.2.1! jason 482: checksum = ssh_crc32((unsigned char *) buffer_ptr(&outgoing_packet),
! 483: buffer_len(&outgoing_packet));
1.14 markus 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) {
1.32 markus 572: /* random padding */
1.25 markus 573: for (i = 0; i < padlen; i++) {
574: if (i % 4 == 0)
575: rand = arc4random();
576: cp[i] = rand & 0xff;
577: rand <<= 8;
578: }
1.32 markus 579: } else {
580: /* clear padding */
581: memset(cp, 0, padlen);
1.25 markus 582: }
583: /* packet_length includes payload, padding and padding length field */
584: packet_length = buffer_len(&outgoing_packet) - 4;
585: cp = buffer_ptr(&outgoing_packet);
586: PUT_32BIT(cp, packet_length);
587: cp[4] = padlen & 0xff;
588: DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
589:
590: /* compute MAC over seqnr and packet(length fields, payload, padding) */
591: if (mac && mac->enabled) {
592: macbuf = hmac( mac->md, seqnr,
593: (unsigned char *) buffer_ptr(&outgoing_packet),
594: buffer_len(&outgoing_packet),
595: mac->key, mac->key_len
596: );
597: DBG(debug("done calc HMAC out #%d", seqnr));
598: }
599: /* encrypt packet and append to output buffer. */
600: buffer_append_space(&output, &cp, buffer_len(&outgoing_packet));
601: packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet),
602: buffer_len(&outgoing_packet));
603: /* append unencrypted MAC */
604: if (mac && mac->enabled)
605: buffer_append(&output, (char *)macbuf, mac->mac_len);
606: #ifdef PACKET_DEBUG
607: fprintf(stderr, "encrypted: ");
608: buffer_dump(&output);
609: #endif
1.29 markus 610: /* increment sequence number for outgoing packets */
611: if (++seqnr == 0)
612: log("outgoing seqnr wraps around");
1.25 markus 613: buffer_clear(&outgoing_packet);
614:
615: if (type == SSH2_MSG_NEWKEYS) {
616: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
617: fatal("packet_send2: no KEX");
618: if (mac->md != NULL)
619: mac->enabled = 1;
1.31 markus 620: DBG(debug("cipher_set_key_iv send_context"));
1.25 markus 621: cipher_set_key_iv(&send_context, enc->type,
622: enc->key, enc->key_len,
623: enc->iv, enc->iv_len);
624: clear_enc_keys(enc, kex->we_need);
625: if (comp->type != 0 && comp->enabled == 0) {
626: comp->enabled = 1;
627: if (! packet_compression)
628: packet_start_compression(6);
629: }
630: }
631: }
632:
633: void
634: packet_send()
635: {
636: if (use_ssh2_packet_format)
637: packet_send2();
638: else
639: packet_send1();
640: DBG(debug("packet_send done"));
641: }
642:
643: /*
1.16 markus 644: * Waits until a packet has been received, and returns its type. Note that
645: * no other data is processed until this returns, so this function should not
646: * be used during the interactive session.
647: */
1.1 deraadt 648:
1.2 provos 649: int
650: packet_read(int *payload_len_ptr)
1.1 deraadt 651: {
1.14 markus 652: int type, len;
653: fd_set set;
654: char buf[8192];
1.25 markus 655: DBG(debug("packet_read()"));
1.14 markus 656:
657: /* Since we are blocking, ensure that all written packets have been sent. */
658: packet_write_wait();
659:
660: /* Stay in the loop until we have received a complete packet. */
661: for (;;) {
662: /* Try to read a packet from the buffer. */
663: type = packet_read_poll(payload_len_ptr);
1.32 markus 664: if (!use_ssh2_packet_format && (
665: type == SSH_SMSG_SUCCESS
1.14 markus 666: || type == SSH_SMSG_FAILURE
667: || type == SSH_CMSG_EOF
1.32 markus 668: || type == SSH_CMSG_EXIT_CONFIRMATION))
1.14 markus 669: packet_integrity_check(*payload_len_ptr, 0, type);
670: /* If we got a packet, return it. */
671: if (type != SSH_MSG_NONE)
672: return type;
1.16 markus 673: /*
674: * Otherwise, wait for some data to arrive, add it to the
675: * buffer, and try again.
676: */
1.14 markus 677: FD_ZERO(&set);
678: FD_SET(connection_in, &set);
1.16 markus 679:
1.14 markus 680: /* Wait for some data to arrive. */
681: select(connection_in + 1, &set, NULL, NULL, NULL);
1.16 markus 682:
1.14 markus 683: /* Read data from the socket. */
684: len = read(connection_in, buf, sizeof(buf));
1.18 markus 685: if (len == 0) {
686: log("Connection closed by %.200s", get_remote_ipaddr());
687: fatal_cleanup();
688: }
1.14 markus 689: if (len < 0)
690: fatal("Read from socket failed: %.100s", strerror(errno));
691: /* Append it to the buffer. */
692: packet_process_incoming(buf, len);
693: }
694: /* NOTREACHED */
1.1 deraadt 695: }
696:
1.16 markus 697: /*
698: * Waits until a packet has been received, verifies that its type matches
699: * that given, and gives a fatal error and exits if there is a mismatch.
700: */
1.1 deraadt 701:
1.2 provos 702: void
703: packet_read_expect(int *payload_len_ptr, int expected_type)
1.1 deraadt 704: {
1.14 markus 705: int type;
1.1 deraadt 706:
1.14 markus 707: type = packet_read(payload_len_ptr);
708: if (type != expected_type)
709: packet_disconnect("Protocol error: expected packet type %d, got %d",
1.25 markus 710: expected_type, type);
1.1 deraadt 711: }
712:
713: /* Checks if a full packet is available in the data received so far via
1.14 markus 714: * packet_process_incoming. If so, reads the packet; otherwise returns
715: * SSH_MSG_NONE. This does not wait for data from the connection.
716: *
717: * SSH_MSG_DISCONNECT is handled specially here. Also,
718: * SSH_MSG_IGNORE messages are skipped by this function and are never returned
719: * to higher levels.
720: *
721: * The returned payload_len does include space consumed by:
722: * Packet length
723: * Padding
724: * Packet type
725: * Check bytes
726: */
1.1 deraadt 727:
1.2 provos 728: int
1.25 markus 729: packet_read_poll1(int *payload_len_ptr)
1.1 deraadt 730: {
1.14 markus 731: unsigned int len, padded_len;
732: unsigned char *ucp;
1.25 markus 733: char buf[8], *cp;
1.14 markus 734: unsigned int checksum, stored_checksum;
735:
736: /* Check if input size is less than minimum packet size. */
737: if (buffer_len(&input) < 4 + 8)
738: return SSH_MSG_NONE;
739: /* Get length of incoming packet. */
740: ucp = (unsigned char *) buffer_ptr(&input);
741: len = GET_32BIT(ucp);
742: if (len < 1 + 2 + 2 || len > 256 * 1024)
743: packet_disconnect("Bad packet length %d.", len);
744: padded_len = (len + 8) & ~7;
745:
746: /* Check if the packet has been entirely received. */
747: if (buffer_len(&input) < 4 + padded_len)
748: return SSH_MSG_NONE;
749:
750: /* The entire packet is in buffer. */
751:
752: /* Consume packet length. */
753: buffer_consume(&input, 4);
754:
755: /* Copy data to incoming_packet. */
756: buffer_clear(&incoming_packet);
757: buffer_append_space(&incoming_packet, &cp, padded_len);
758: packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len);
759: buffer_consume(&input, padded_len);
1.1 deraadt 760:
761: #ifdef PACKET_DEBUG
1.14 markus 762: fprintf(stderr, "read_poll plain: ");
763: buffer_dump(&incoming_packet);
1.1 deraadt 764: #endif
765:
1.14 markus 766: /* Compute packet checksum. */
1.32.2.1! jason 767: checksum = ssh_crc32((unsigned char *) buffer_ptr(&incoming_packet),
1.25 markus 768: buffer_len(&incoming_packet) - 4);
1.14 markus 769:
770: /* Skip padding. */
771: buffer_consume(&incoming_packet, 8 - len % 8);
772:
773: /* Test check bytes. */
774:
775: if (len != buffer_len(&incoming_packet))
776: packet_disconnect("packet_read_poll: len %d != buffer_len %d.",
1.25 markus 777: len, buffer_len(&incoming_packet));
1.14 markus 778:
779: ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4;
780: stored_checksum = GET_32BIT(ucp);
781: if (checksum != stored_checksum)
782: packet_disconnect("Corrupted check bytes on input.");
783: buffer_consume_end(&incoming_packet, 4);
784:
785: /* If using packet compression, decompress the packet. */
786: if (packet_compression) {
787: buffer_clear(&compression_buffer);
788: buffer_uncompress(&incoming_packet, &compression_buffer);
789: buffer_clear(&incoming_packet);
790: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1.25 markus 791: buffer_len(&compression_buffer));
1.14 markus 792: }
793: /* Get packet type. */
794: buffer_get(&incoming_packet, &buf[0], 1);
795:
796: /* Return length of payload (without type field). */
797: *payload_len_ptr = buffer_len(&incoming_packet);
798:
799: /* Return type. */
800: return (unsigned char) buf[0];
1.1 deraadt 801: }
1.14 markus 802:
1.25 markus 803: int
804: packet_read_poll2(int *payload_len_ptr)
805: {
806: unsigned int padlen, need;
807: unsigned char buf[8], *macbuf;
808: unsigned char *ucp;
809: char *cp;
810: static unsigned int packet_length = 0;
811: static unsigned int seqnr = 0;
812: int type;
813: int maclen, block_size;
814: Enc *enc = NULL;
815: Mac *mac = NULL;
816: Comp *comp = NULL;
817:
818: if (kex != NULL) {
819: enc = &kex->enc[MODE_IN];
820: mac = &kex->mac[MODE_IN];
821: comp = &kex->comp[MODE_IN];
822: }
823: maclen = mac && mac->enabled ? mac->mac_len : 0;
824: block_size = enc ? enc->block_size : 8;
825:
826: if (packet_length == 0) {
827: /*
828: * check if input size is less than the cipher block size,
829: * decrypt first block and extract length of incoming packet
830: */
831: if (buffer_len(&input) < block_size)
832: return SSH_MSG_NONE;
833: buffer_clear(&incoming_packet);
834: buffer_append_space(&incoming_packet, &cp, block_size);
835: packet_decrypt(&receive_context, cp, buffer_ptr(&input),
836: block_size);
837: ucp = (unsigned char *) buffer_ptr(&incoming_packet);
838: packet_length = GET_32BIT(ucp);
839: if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
840: buffer_dump(&incoming_packet);
841: packet_disconnect("Bad packet length %d.", packet_length);
842: }
843: DBG(debug("input: packet len %d", packet_length+4));
844: buffer_consume(&input, block_size);
845: }
846: /* we have a partial packet of block_size bytes */
847: need = 4 + packet_length - block_size;
848: DBG(debug("partial packet %d, need %d, maclen %d", block_size,
849: need, maclen));
850: if (need % block_size != 0)
851: fatal("padding error: need %d block %d mod %d",
852: need, block_size, need % block_size);
853: /*
854: * check if the entire packet has been received and
855: * decrypt into incoming_packet
856: */
857: if (buffer_len(&input) < need + maclen)
858: return SSH_MSG_NONE;
859: #ifdef PACKET_DEBUG
860: fprintf(stderr, "read_poll enc/full: ");
861: buffer_dump(&input);
862: #endif
863: buffer_append_space(&incoming_packet, &cp, need);
864: packet_decrypt(&receive_context, cp, buffer_ptr(&input), need);
865: buffer_consume(&input, need);
866: /*
867: * compute MAC over seqnr and packet,
868: * increment sequence number for incoming packet
869: */
1.29 markus 870: if (mac && mac->enabled) {
1.25 markus 871: macbuf = hmac( mac->md, seqnr,
872: (unsigned char *) buffer_ptr(&incoming_packet),
873: buffer_len(&incoming_packet),
874: mac->key, mac->key_len
875: );
876: if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
877: packet_disconnect("Corrupted HMAC on input.");
878: DBG(debug("HMAC #%d ok", seqnr));
879: buffer_consume(&input, mac->mac_len);
880: }
1.29 markus 881: if (++seqnr == 0)
882: log("incoming seqnr wraps around");
1.25 markus 883:
884: /* get padlen */
885: cp = buffer_ptr(&incoming_packet) + 4;
886: padlen = *cp & 0xff;
887: DBG(debug("input: padlen %d", padlen));
888: if (padlen < 4)
889: packet_disconnect("Corrupted padlen %d on input.", padlen);
890:
891: /* skip packet size + padlen, discard padding */
892: buffer_consume(&incoming_packet, 4 + 1);
893: buffer_consume_end(&incoming_packet, padlen);
894:
895: DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
896: if (comp && comp->enabled) {
897: buffer_clear(&compression_buffer);
898: buffer_uncompress(&incoming_packet, &compression_buffer);
899: buffer_clear(&incoming_packet);
900: buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
901: buffer_len(&compression_buffer));
902: DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet)));
903: }
904: /*
905: * get packet type, implies consume.
906: * return length of payload (without type field)
907: */
908: buffer_get(&incoming_packet, (char *)&buf[0], 1);
909: *payload_len_ptr = buffer_len(&incoming_packet);
910:
911: /* reset for next packet */
912: packet_length = 0;
913:
914: /* extract packet type */
915: type = (unsigned char)buf[0];
916:
917: if (type == SSH2_MSG_NEWKEYS) {
918: if (kex==NULL || mac==NULL || enc==NULL || comp==NULL)
919: fatal("packet_read_poll2: no KEX");
920: if (mac->md != NULL)
921: mac->enabled = 1;
1.31 markus 922: DBG(debug("cipher_set_key_iv receive_context"));
1.25 markus 923: cipher_set_key_iv(&receive_context, enc->type,
924: enc->key, enc->key_len,
925: enc->iv, enc->iv_len);
926: clear_enc_keys(enc, kex->we_need);
927: if (comp->type != 0 && comp->enabled == 0) {
928: comp->enabled = 1;
929: if (! packet_compression)
930: packet_start_compression(6);
931: }
932: }
933:
934: #ifdef PACKET_DEBUG
935: fprintf(stderr, "read/plain[%d]:\r\n",type);
936: buffer_dump(&incoming_packet);
937: #endif
938: return (unsigned char)type;
939: }
940:
941: int
942: packet_read_poll(int *payload_len_ptr)
943: {
944: char *msg;
945: for (;;) {
946: int type = use_ssh2_packet_format ?
947: packet_read_poll2(payload_len_ptr):
948: packet_read_poll1(payload_len_ptr);
949:
950: if(compat20) {
951: int reason;
952: if (type != 0)
953: DBG(debug("received packet type %d", type));
954: switch(type) {
955: case SSH2_MSG_IGNORE:
956: break;
957: case SSH2_MSG_DEBUG:
958: packet_get_char();
959: msg = packet_get_string(NULL);
960: debug("Remote: %.900s", msg);
961: xfree(msg);
962: msg = packet_get_string(NULL);
963: xfree(msg);
964: break;
965: case SSH2_MSG_DISCONNECT:
966: reason = packet_get_int();
967: msg = packet_get_string(NULL);
968: log("Received disconnect: %d: %.900s", reason, msg);
969: xfree(msg);
970: fatal_cleanup();
971: break;
972: default:
973: return type;
974: break;
975: }
976: } else {
977: switch(type) {
978: case SSH_MSG_IGNORE:
979: break;
980: case SSH_MSG_DEBUG:
981: msg = packet_get_string(NULL);
982: debug("Remote: %.900s", msg);
983: xfree(msg);
984: break;
985: case SSH_MSG_DISCONNECT:
986: msg = packet_get_string(NULL);
987: log("Received disconnect: %.900s", msg);
988: fatal_cleanup();
989: xfree(msg);
990: break;
991: default:
992: if (type != 0)
993: DBG(debug("received packet type %d", type));
994: return type;
995: break;
996: }
997: }
998: }
999: }
1000:
1.16 markus 1001: /*
1002: * Buffers the given amount of input characters. This is intended to be used
1003: * together with packet_read_poll.
1004: */
1.1 deraadt 1005:
1.2 provos 1006: void
1007: packet_process_incoming(const char *buf, unsigned int len)
1.1 deraadt 1008: {
1.14 markus 1009: buffer_append(&input, buf, len);
1.1 deraadt 1010: }
1011:
1012: /* Returns a character from the packet. */
1013:
1.2 provos 1014: unsigned int
1015: packet_get_char()
1.1 deraadt 1016: {
1.14 markus 1017: char ch;
1018: buffer_get(&incoming_packet, &ch, 1);
1019: return (unsigned char) ch;
1.1 deraadt 1020: }
1021:
1022: /* Returns an integer from the packet data. */
1023:
1.2 provos 1024: unsigned int
1025: packet_get_int()
1.1 deraadt 1026: {
1.14 markus 1027: return buffer_get_int(&incoming_packet);
1.1 deraadt 1028: }
1029:
1.16 markus 1030: /*
1031: * Returns an arbitrary precision integer from the packet data. The integer
1032: * must have been initialized before this call.
1033: */
1.1 deraadt 1034:
1.2 provos 1035: void
1.14 markus 1036: packet_get_bignum(BIGNUM * value, int *length_ptr)
1.1 deraadt 1037: {
1.14 markus 1038: *length_ptr = buffer_get_bignum(&incoming_packet, value);
1.24 markus 1039: }
1040:
1041: void
1042: packet_get_bignum2(BIGNUM * value, int *length_ptr)
1043: {
1044: *length_ptr = buffer_get_bignum2(&incoming_packet, value);
1045: }
1046:
1047: char *
1048: packet_get_raw(int *length_ptr)
1049: {
1050: int bytes = buffer_len(&incoming_packet);
1051: if (length_ptr != NULL)
1052: *length_ptr = bytes;
1053: return buffer_ptr(&incoming_packet);
1.28 markus 1054: }
1055:
1056: int
1057: packet_remaining(void)
1058: {
1059: return buffer_len(&incoming_packet);
1.1 deraadt 1060: }
1061:
1.16 markus 1062: /*
1063: * Returns a string from the packet data. The string is allocated using
1064: * xmalloc; it is the responsibility of the calling program to free it when
1065: * no longer needed. The length_ptr argument may be NULL, or point to an
1066: * integer into which the length of the string is stored.
1067: */
1.1 deraadt 1068:
1.16 markus 1069: char *
1.14 markus 1070: packet_get_string(unsigned int *length_ptr)
1.1 deraadt 1071: {
1.14 markus 1072: return buffer_get_string(&incoming_packet, length_ptr);
1.1 deraadt 1073: }
1074:
1.16 markus 1075: /*
1076: * Sends a diagnostic message from the server to the client. This message
1077: * can be sent at any time (but not while constructing another message). The
1078: * message is printed immediately, but only if the client is being executed
1079: * in verbose mode. These messages are primarily intended to ease debugging
1080: * authentication problems. The length of the formatted message must not
1081: * exceed 1024 bytes. This will automatically call packet_write_wait.
1082: */
1.1 deraadt 1083:
1.2 provos 1084: void
1.14 markus 1085: packet_send_debug(const char *fmt,...)
1.1 deraadt 1086: {
1.14 markus 1087: char buf[1024];
1088: va_list args;
1089:
1090: va_start(args, fmt);
1091: vsnprintf(buf, sizeof(buf), fmt, args);
1092: va_end(args);
1093:
1.30 markus 1094: if (compat20) {
1095: packet_start(SSH2_MSG_DEBUG);
1096: packet_put_char(0); /* bool: always display */
1097: packet_put_cstring(buf);
1098: packet_put_cstring("");
1099: } else {
1100: packet_start(SSH_MSG_DEBUG);
1101: packet_put_cstring(buf);
1102: }
1.14 markus 1103: packet_send();
1104: packet_write_wait();
1.1 deraadt 1105: }
1106:
1.16 markus 1107: /*
1108: * Logs the error plus constructs and sends a disconnect packet, closes the
1109: * connection, and exits. This function never returns. The error message
1110: * should not contain a newline. The length of the formatted message must
1111: * not exceed 1024 bytes.
1112: */
1.1 deraadt 1113:
1.2 provos 1114: void
1.14 markus 1115: packet_disconnect(const char *fmt,...)
1.1 deraadt 1116: {
1.14 markus 1117: char buf[1024];
1118: va_list args;
1119: static int disconnecting = 0;
1120: if (disconnecting) /* Guard against recursive invocations. */
1121: fatal("packet_disconnect called recursively.");
1122: disconnecting = 1;
1123:
1.16 markus 1124: /*
1125: * Format the message. Note that the caller must make sure the
1126: * message is of limited size.
1127: */
1.14 markus 1128: va_start(args, fmt);
1129: vsnprintf(buf, sizeof(buf), fmt, args);
1130: va_end(args);
1131:
1132: /* Send the disconnect message to the other side, and wait for it to get sent. */
1.25 markus 1133: if (compat20) {
1134: packet_start(SSH2_MSG_DISCONNECT);
1135: packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1136: packet_put_cstring(buf);
1137: packet_put_cstring("");
1138: } else {
1139: packet_start(SSH_MSG_DISCONNECT);
1140: packet_put_string(buf, strlen(buf));
1141: }
1.14 markus 1142: packet_send();
1143: packet_write_wait();
1144:
1145: /* Stop listening for connections. */
1146: channel_stop_listening();
1147:
1148: /* Close the connection. */
1149: packet_close();
1.1 deraadt 1150:
1.14 markus 1151: /* Display the error locally and exit. */
1.17 markus 1152: log("Disconnecting: %.100s", buf);
1153: fatal_cleanup();
1.1 deraadt 1154: }
1155:
1.16 markus 1156: /* Checks if there is any buffered output, and tries to write some of the output. */
1.1 deraadt 1157:
1.2 provos 1158: void
1159: packet_write_poll()
1.1 deraadt 1160: {
1.14 markus 1161: int len = buffer_len(&output);
1162: if (len > 0) {
1163: len = write(connection_out, buffer_ptr(&output), len);
1164: if (len <= 0) {
1165: if (errno == EAGAIN)
1166: return;
1167: else
1168: fatal("Write failed: %.100s", strerror(errno));
1169: }
1170: buffer_consume(&output, len);
1171: }
1.1 deraadt 1172: }
1173:
1.16 markus 1174: /*
1175: * Calls packet_write_poll repeatedly until all pending output data has been
1176: * written.
1177: */
1.1 deraadt 1178:
1.2 provos 1179: void
1180: packet_write_wait()
1.1 deraadt 1181: {
1.14 markus 1182: packet_write_poll();
1183: while (packet_have_data_to_write()) {
1184: fd_set set;
1185: FD_ZERO(&set);
1186: FD_SET(connection_out, &set);
1187: select(connection_out + 1, NULL, &set, NULL, NULL);
1188: packet_write_poll();
1189: }
1.1 deraadt 1190: }
1191:
1192: /* Returns true if there is buffered data to write to the connection. */
1193:
1.2 provos 1194: int
1195: packet_have_data_to_write()
1.1 deraadt 1196: {
1.14 markus 1197: return buffer_len(&output) != 0;
1.1 deraadt 1198: }
1199:
1200: /* Returns true if there is not too much data to write to the connection. */
1201:
1.2 provos 1202: int
1203: packet_not_very_much_data_to_write()
1.1 deraadt 1204: {
1.14 markus 1205: if (interactive_mode)
1206: return buffer_len(&output) < 16384;
1207: else
1208: return buffer_len(&output) < 128 * 1024;
1.1 deraadt 1209: }
1210:
1211: /* Informs that the current session is interactive. Sets IP flags for that. */
1212:
1.2 provos 1213: void
1214: packet_set_interactive(int interactive, int keepalives)
1.1 deraadt 1215: {
1.14 markus 1216: int on = 1;
1.1 deraadt 1217:
1.14 markus 1218: /* Record that we are in interactive mode. */
1219: interactive_mode = interactive;
1.1 deraadt 1220:
1.19 markus 1221: /* Only set socket options if using a socket. */
1222: if (!packet_connection_is_on_socket())
1.14 markus 1223: return;
1224: if (keepalives) {
1225: /* Set keepalives if requested. */
1226: if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on,
1.19 markus 1227: sizeof(on)) < 0)
1.14 markus 1228: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1229: }
1.19 markus 1230: /*
1231: * IPTOS_LOWDELAY, TCP_NODELAY and IPTOS_THROUGHPUT are IPv4 only
1232: */
1233: if (!packet_connection_is_ipv4())
1234: return;
1.14 markus 1235: if (interactive) {
1.16 markus 1236: /*
1237: * Set IP options for an interactive connection. Use
1238: * IPTOS_LOWDELAY and TCP_NODELAY.
1239: */
1.14 markus 1240: int lowdelay = IPTOS_LOWDELAY;
1241: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay,
1.19 markus 1242: sizeof(lowdelay)) < 0)
1.14 markus 1243: error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno));
1244: if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on,
1.19 markus 1245: sizeof(on)) < 0)
1.14 markus 1246: error("setsockopt TCP_NODELAY: %.100s", strerror(errno));
1247: } else {
1.16 markus 1248: /*
1249: * Set IP options for a non-interactive connection. Use
1250: * IPTOS_THROUGHPUT.
1251: */
1.14 markus 1252: int throughput = IPTOS_THROUGHPUT;
1253: if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput,
1.19 markus 1254: sizeof(throughput)) < 0)
1.14 markus 1255: error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno));
1256: }
1.1 deraadt 1257: }
1258:
1259: /* Returns true if the current connection is interactive. */
1260:
1.2 provos 1261: int
1262: packet_is_interactive()
1.1 deraadt 1263: {
1.14 markus 1264: return interactive_mode;
1.12 markus 1265: }
1266:
1267: int
1268: packet_set_maxsize(int s)
1269: {
1.14 markus 1270: static int called = 0;
1271: if (called) {
1.25 markus 1272: log("packet_set_maxsize: called twice: old %d new %d",
1273: max_packet_size, s);
1.14 markus 1274: return -1;
1275: }
1276: if (s < 4 * 1024 || s > 1024 * 1024) {
1277: log("packet_set_maxsize: bad size %d", s);
1278: return -1;
1279: }
1280: log("packet_set_maxsize: setting to %d", s);
1281: max_packet_size = s;
1282: return s;
1.1 deraadt 1283: }
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