1 /* $OpenBSD: packet.c,v 1.128 2006/03/25 13:17:02 djm Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * This file contains code implementing the packet protocol and communication
7 * with the other side. This same code is used both on client and server side.
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
16 * SSH2 packet format added by Markus Friedl.
17 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
19 * Redistribution and use in source and binary forms, with or without
20 * modification, are permitted provided that the following conditions
22 * 1. Redistributions of source code must retain the above copyright
23 * notice, this list of conditions and the following disclaimer.
24 * 2. Redistributions in binary form must reproduce the above copyright
25 * notice, this list of conditions and the following disclaimer in the
26 * documentation and/or other materials provided with the distribution.
28 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
30 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
31 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
33 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
37 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 #include "openbsd-compat/sys-queue.h"
43 #include <netinet/in_systm.h>
44 #include <netinet/ip.h>
76 * This variable contains the file descriptors used for communicating with
77 * the other side. connection_in is used for reading; connection_out for
78 * writing. These can be the same descriptor, in which case it is assumed to
81 static int connection_in = -1;
82 static int connection_out = -1;
84 /* Protocol flags for the remote side. */
85 static u_int remote_protocol_flags = 0;
87 /* Encryption context for receiving data. This is only used for decryption. */
88 static CipherContext receive_context;
90 /* Encryption context for sending data. This is only used for encryption. */
91 static CipherContext send_context;
93 /* Buffer for raw input data from the socket. */
96 /* Buffer for raw output data going to the socket. */
99 /* Buffer for the partial outgoing packet being constructed. */
100 static Buffer outgoing_packet;
102 /* Buffer for the incoming packet currently being processed. */
103 static Buffer incoming_packet;
105 /* Scratch buffer for packet compression/decompression. */
106 static Buffer compression_buffer;
107 static int compression_buffer_ready = 0;
109 /* Flag indicating whether packet compression/decompression is enabled. */
110 static int packet_compression = 0;
112 /* default maximum packet size */
113 u_int max_packet_size = 32768;
115 /* Flag indicating whether this module has been initialized. */
116 static int initialized = 0;
118 /* Set to true if the connection is interactive. */
119 static int interactive_mode = 0;
121 /* Set to true if we are the server side. */
122 static int server_side = 0;
124 /* Set to true if we are authenticated. */
125 static int after_authentication = 0;
127 /* Session key information for Encryption and MAC */
128 Newkeys *newkeys[MODE_MAX];
129 static struct packet_state {
135 static u_int64_t max_blocks_in, max_blocks_out;
136 static u_int32_t rekey_limit;
138 /* Session key for protocol v1 */
139 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
140 static u_int ssh1_keylen;
142 /* roundup current message to extra_pad bytes */
143 static u_char extra_pad = 0;
146 TAILQ_ENTRY(packet) next;
150 TAILQ_HEAD(, packet) outgoing;
153 * Sets the descriptors used for communication. Disables encryption until
154 * packet_set_encryption_key is called.
157 packet_set_connection(int fd_in, int fd_out)
159 Cipher *none = cipher_by_name("none");
162 fatal("packet_set_connection: cannot load cipher 'none'");
163 connection_in = fd_in;
164 connection_out = fd_out;
165 cipher_init(&send_context, none, (const u_char *)"",
166 0, NULL, 0, CIPHER_ENCRYPT);
167 cipher_init(&receive_context, none, (const u_char *)"",
168 0, NULL, 0, CIPHER_DECRYPT);
169 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
173 buffer_init(&output);
174 buffer_init(&outgoing_packet);
175 buffer_init(&incoming_packet);
176 TAILQ_INIT(&outgoing);
180 /* Returns 1 if remote host is connected via socket, 0 if not. */
183 packet_connection_is_on_socket(void)
185 struct sockaddr_storage from, to;
186 socklen_t fromlen, tolen;
188 /* filedescriptors in and out are the same, so it's a socket */
189 if (connection_in == connection_out)
191 fromlen = sizeof(from);
192 memset(&from, 0, sizeof(from));
193 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
196 memset(&to, 0, sizeof(to));
197 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
199 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
201 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
207 * Exports an IV from the CipherContext required to export the key
208 * state back from the unprivileged child to the privileged parent
213 packet_get_keyiv(int mode, u_char *iv, u_int len)
217 if (mode == MODE_OUT)
220 cc = &receive_context;
222 cipher_get_keyiv(cc, iv, len);
226 packet_get_keycontext(int mode, u_char *dat)
230 if (mode == MODE_OUT)
233 cc = &receive_context;
235 return (cipher_get_keycontext(cc, dat));
239 packet_set_keycontext(int mode, u_char *dat)
243 if (mode == MODE_OUT)
246 cc = &receive_context;
248 cipher_set_keycontext(cc, dat);
252 packet_get_keyiv_len(int mode)
256 if (mode == MODE_OUT)
259 cc = &receive_context;
261 return (cipher_get_keyiv_len(cc));
265 packet_set_iv(int mode, u_char *dat)
269 if (mode == MODE_OUT)
272 cc = &receive_context;
274 cipher_set_keyiv(cc, dat);
278 packet_get_ssh1_cipher(void)
280 return (cipher_get_number(receive_context.cipher));
284 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets)
286 struct packet_state *state;
288 state = (mode == MODE_IN) ? &p_read : &p_send;
289 *seqnr = state->seqnr;
290 *blocks = state->blocks;
291 *packets = state->packets;
295 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets)
297 struct packet_state *state;
299 state = (mode == MODE_IN) ? &p_read : &p_send;
300 state->seqnr = seqnr;
301 state->blocks = blocks;
302 state->packets = packets;
305 /* returns 1 if connection is via ipv4 */
308 packet_connection_is_ipv4(void)
310 struct sockaddr_storage to;
311 socklen_t tolen = sizeof(to);
313 memset(&to, 0, sizeof(to));
314 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
316 if (to.ss_family == AF_INET)
319 if (to.ss_family == AF_INET6 &&
320 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
326 /* Sets the connection into non-blocking mode. */
329 packet_set_nonblocking(void)
331 /* Set the socket into non-blocking mode. */
332 set_nonblock(connection_in);
334 if (connection_out != connection_in)
335 set_nonblock(connection_out);
338 /* Returns the socket used for reading. */
341 packet_get_connection_in(void)
343 return connection_in;
346 /* Returns the descriptor used for writing. */
349 packet_get_connection_out(void)
351 return connection_out;
354 /* Closes the connection and clears and frees internal data structures. */
362 if (connection_in == connection_out) {
363 shutdown(connection_out, SHUT_RDWR);
364 close(connection_out);
366 close(connection_in);
367 close(connection_out);
370 buffer_free(&output);
371 buffer_free(&outgoing_packet);
372 buffer_free(&incoming_packet);
373 if (compression_buffer_ready) {
374 buffer_free(&compression_buffer);
375 buffer_compress_uninit();
377 cipher_cleanup(&send_context);
378 cipher_cleanup(&receive_context);
381 /* Sets remote side protocol flags. */
384 packet_set_protocol_flags(u_int protocol_flags)
386 remote_protocol_flags = protocol_flags;
389 /* Returns the remote protocol flags set earlier by the above function. */
392 packet_get_protocol_flags(void)
394 return remote_protocol_flags;
398 * Starts packet compression from the next packet on in both directions.
399 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
403 packet_init_compression(void)
405 if (compression_buffer_ready == 1)
407 compression_buffer_ready = 1;
408 buffer_init(&compression_buffer);
412 packet_start_compression(int level)
414 if (packet_compression && !compat20)
415 fatal("Compression already enabled.");
416 packet_compression = 1;
417 packet_init_compression();
418 buffer_compress_init_send(level);
419 buffer_compress_init_recv();
423 * Causes any further packets to be encrypted using the given key. The same
424 * key is used for both sending and reception. However, both directions are
425 * encrypted independently of each other.
429 packet_set_encryption_key(const u_char *key, u_int keylen,
432 Cipher *cipher = cipher_by_number(number);
435 fatal("packet_set_encryption_key: unknown cipher number %d", number);
437 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
438 if (keylen > SSH_SESSION_KEY_LENGTH)
439 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
440 memcpy(ssh1_key, key, keylen);
441 ssh1_keylen = keylen;
442 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
443 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
447 packet_get_encryption_key(u_char *key)
450 return (ssh1_keylen);
451 memcpy(key, ssh1_key, ssh1_keylen);
452 return (ssh1_keylen);
455 /* Start constructing a packet to send. */
457 packet_start(u_char type)
462 DBG(debug("packet_start[%d]", type));
463 len = compat20 ? 6 : 9;
464 memset(buf, 0, len - 1);
466 buffer_clear(&outgoing_packet);
467 buffer_append(&outgoing_packet, buf, len);
470 /* Append payload. */
472 packet_put_char(int value)
476 buffer_append(&outgoing_packet, &ch, 1);
480 packet_put_int(u_int value)
482 buffer_put_int(&outgoing_packet, value);
486 packet_put_string(const void *buf, u_int len)
488 buffer_put_string(&outgoing_packet, buf, len);
492 packet_put_cstring(const char *str)
494 buffer_put_cstring(&outgoing_packet, str);
498 packet_put_raw(const void *buf, u_int len)
500 buffer_append(&outgoing_packet, buf, len);
504 packet_put_bignum(BIGNUM * value)
506 buffer_put_bignum(&outgoing_packet, value);
510 packet_put_bignum2(BIGNUM * value)
512 buffer_put_bignum2(&outgoing_packet, value);
516 * Finalizes and sends the packet. If the encryption key has been set,
517 * encrypts the packet before sending.
529 * If using packet compression, compress the payload of the outgoing
532 if (packet_compression) {
533 buffer_clear(&compression_buffer);
535 buffer_consume(&outgoing_packet, 8);
537 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
538 buffer_compress(&outgoing_packet, &compression_buffer);
539 buffer_clear(&outgoing_packet);
540 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
541 buffer_len(&compression_buffer));
543 /* Compute packet length without padding (add checksum, remove padding). */
544 len = buffer_len(&outgoing_packet) + 4 - 8;
546 /* Insert padding. Initialized to zero in packet_start1() */
547 padding = 8 - len % 8;
548 if (!send_context.plaintext) {
549 cp = buffer_ptr(&outgoing_packet);
550 for (i = 0; i < padding; i++) {
553 cp[7 - i] = rnd & 0xff;
557 buffer_consume(&outgoing_packet, 8 - padding);
559 /* Add check bytes. */
560 checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
561 buffer_len(&outgoing_packet));
562 PUT_32BIT(buf, checksum);
563 buffer_append(&outgoing_packet, buf, 4);
566 fprintf(stderr, "packet_send plain: ");
567 buffer_dump(&outgoing_packet);
570 /* Append to output. */
572 buffer_append(&output, buf, 4);
573 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
574 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
575 buffer_len(&outgoing_packet));
578 fprintf(stderr, "encrypted: ");
579 buffer_dump(&output);
582 buffer_clear(&outgoing_packet);
585 * Note that the packet is now only buffered in output. It won't be
586 * actually sent until packet_write_wait or packet_write_poll is
592 set_newkeys(int mode)
598 u_int64_t *max_blocks;
601 debug2("set_newkeys: mode %d", mode);
603 if (mode == MODE_OUT) {
605 crypt_type = CIPHER_ENCRYPT;
606 p_send.packets = p_send.blocks = 0;
607 max_blocks = &max_blocks_out;
609 cc = &receive_context;
610 crypt_type = CIPHER_DECRYPT;
611 p_read.packets = p_read.blocks = 0;
612 max_blocks = &max_blocks_in;
614 if (newkeys[mode] != NULL) {
615 debug("set_newkeys: rekeying");
617 enc = &newkeys[mode]->enc;
618 mac = &newkeys[mode]->mac;
619 comp = &newkeys[mode]->comp;
620 memset(mac->key, 0, mac->key_len);
627 xfree(newkeys[mode]);
629 newkeys[mode] = kex_get_newkeys(mode);
630 if (newkeys[mode] == NULL)
631 fatal("newkeys: no keys for mode %d", mode);
632 enc = &newkeys[mode]->enc;
633 mac = &newkeys[mode]->mac;
634 comp = &newkeys[mode]->comp;
637 DBG(debug("cipher_init_context: %d", mode));
638 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
639 enc->iv, enc->block_size, crypt_type);
640 /* Deleting the keys does not gain extra security */
641 /* memset(enc->iv, 0, enc->block_size);
642 memset(enc->key, 0, enc->key_len); */
643 if ((comp->type == COMP_ZLIB ||
644 (comp->type == COMP_DELAYED && after_authentication)) &&
645 comp->enabled == 0) {
646 packet_init_compression();
647 if (mode == MODE_OUT)
648 buffer_compress_init_send(6);
650 buffer_compress_init_recv();
654 * The 2^(blocksize*2) limit is too expensive for 3DES,
655 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
657 if (enc->block_size >= 16)
658 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
660 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
662 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
666 * Delayed compression for SSH2 is enabled after authentication:
667 * This happans on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
668 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
671 packet_enable_delayed_compress(void)
677 * Remember that we are past the authentication step, so rekeying
678 * with COMP_DELAYED will turn on compression immediately.
680 after_authentication = 1;
681 for (mode = 0; mode < MODE_MAX; mode++) {
682 comp = &newkeys[mode]->comp;
683 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
684 packet_init_compression();
685 if (mode == MODE_OUT)
686 buffer_compress_init_send(6);
688 buffer_compress_init_recv();
695 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
698 packet_send2_wrapped(void)
700 u_char type, *cp, *macbuf = NULL;
702 u_int packet_length = 0;
710 if (newkeys[MODE_OUT] != NULL) {
711 enc = &newkeys[MODE_OUT]->enc;
712 mac = &newkeys[MODE_OUT]->mac;
713 comp = &newkeys[MODE_OUT]->comp;
715 block_size = enc ? enc->block_size : 8;
717 cp = buffer_ptr(&outgoing_packet);
721 fprintf(stderr, "plain: ");
722 buffer_dump(&outgoing_packet);
725 if (comp && comp->enabled) {
726 len = buffer_len(&outgoing_packet);
727 /* skip header, compress only payload */
728 buffer_consume(&outgoing_packet, 5);
729 buffer_clear(&compression_buffer);
730 buffer_compress(&outgoing_packet, &compression_buffer);
731 buffer_clear(&outgoing_packet);
732 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
733 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
734 buffer_len(&compression_buffer));
735 DBG(debug("compression: raw %d compressed %d", len,
736 buffer_len(&outgoing_packet)));
739 /* sizeof (packet_len + pad_len + payload) */
740 len = buffer_len(&outgoing_packet);
743 * calc size of padding, alloc space, get random data,
744 * minimum padding is 4 bytes
746 padlen = block_size - (len % block_size);
748 padlen += block_size;
750 /* will wrap if extra_pad+padlen > 255 */
751 extra_pad = roundup(extra_pad, block_size);
752 pad = extra_pad - ((len + padlen) % extra_pad);
753 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
754 pad, len, padlen, extra_pad);
758 cp = buffer_append_space(&outgoing_packet, padlen);
759 if (enc && !send_context.plaintext) {
761 for (i = 0; i < padlen; i++) {
769 memset(cp, 0, padlen);
771 /* packet_length includes payload, padding and padding length field */
772 packet_length = buffer_len(&outgoing_packet) - 4;
773 cp = buffer_ptr(&outgoing_packet);
774 PUT_32BIT(cp, packet_length);
776 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
778 /* compute MAC over seqnr and packet(length fields, payload, padding) */
779 if (mac && mac->enabled) {
780 macbuf = mac_compute(mac, p_send.seqnr,
781 buffer_ptr(&outgoing_packet),
782 buffer_len(&outgoing_packet));
783 DBG(debug("done calc MAC out #%d", p_send.seqnr));
785 /* encrypt packet and append to output buffer. */
786 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
787 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
788 buffer_len(&outgoing_packet));
789 /* append unencrypted MAC */
790 if (mac && mac->enabled)
791 buffer_append(&output, (char *)macbuf, mac->mac_len);
793 fprintf(stderr, "encrypted: ");
794 buffer_dump(&output);
796 /* increment sequence number for outgoing packets */
797 if (++p_send.seqnr == 0)
798 logit("outgoing seqnr wraps around");
799 if (++p_send.packets == 0)
800 if (!(datafellows & SSH_BUG_NOREKEY))
801 fatal("XXX too many packets with same key");
802 p_send.blocks += (packet_length + 4) / block_size;
803 buffer_clear(&outgoing_packet);
805 if (type == SSH2_MSG_NEWKEYS)
806 set_newkeys(MODE_OUT);
807 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
808 packet_enable_delayed_compress();
814 static int rekeying = 0;
818 cp = buffer_ptr(&outgoing_packet);
821 /* during rekeying we can only send key exchange messages */
823 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
824 (type <= SSH2_MSG_TRANSPORT_MAX))) {
825 debug("enqueue packet: %u", type);
826 p = xmalloc(sizeof(*p));
828 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
829 buffer_init(&outgoing_packet);
830 TAILQ_INSERT_TAIL(&outgoing, p, next);
835 /* rekeying starts with sending KEXINIT */
836 if (type == SSH2_MSG_KEXINIT)
839 packet_send2_wrapped();
841 /* after a NEWKEYS message we can send the complete queue */
842 if (type == SSH2_MSG_NEWKEYS) {
844 while ((p = TAILQ_FIRST(&outgoing))) {
846 debug("dequeue packet: %u", type);
847 buffer_free(&outgoing_packet);
848 memcpy(&outgoing_packet, &p->payload,
850 TAILQ_REMOVE(&outgoing, p, next);
852 packet_send2_wrapped();
864 DBG(debug("packet_send done"));
868 * Waits until a packet has been received, and returns its type. Note that
869 * no other data is processed until this returns, so this function should not
870 * be used during the interactive session.
874 packet_read_seqnr(u_int32_t *seqnr_p)
879 DBG(debug("packet_read()"));
881 setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
884 /* Since we are blocking, ensure that all written packets have been sent. */
887 /* Stay in the loop until we have received a complete packet. */
889 /* Try to read a packet from the buffer. */
890 type = packet_read_poll_seqnr(seqnr_p);
892 type == SSH_SMSG_SUCCESS
893 || type == SSH_SMSG_FAILURE
894 || type == SSH_CMSG_EOF
895 || type == SSH_CMSG_EXIT_CONFIRMATION))
897 /* If we got a packet, return it. */
898 if (type != SSH_MSG_NONE) {
903 * Otherwise, wait for some data to arrive, add it to the
904 * buffer, and try again.
906 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
908 FD_SET(connection_in, setp);
910 /* Wait for some data to arrive. */
911 while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 &&
912 (errno == EAGAIN || errno == EINTR))
915 /* Read data from the socket. */
916 len = read(connection_in, buf, sizeof(buf));
918 logit("Connection closed by %.200s", get_remote_ipaddr());
922 fatal("Read from socket failed: %.100s", strerror(errno));
923 /* Append it to the buffer. */
924 packet_process_incoming(buf, len);
932 return packet_read_seqnr(NULL);
936 * Waits until a packet has been received, verifies that its type matches
937 * that given, and gives a fatal error and exits if there is a mismatch.
941 packet_read_expect(int expected_type)
945 type = packet_read();
946 if (type != expected_type)
947 packet_disconnect("Protocol error: expected packet type %d, got %d",
948 expected_type, type);
951 /* Checks if a full packet is available in the data received so far via
952 * packet_process_incoming. If so, reads the packet; otherwise returns
953 * SSH_MSG_NONE. This does not wait for data from the connection.
955 * SSH_MSG_DISCONNECT is handled specially here. Also,
956 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
961 packet_read_poll1(void)
963 u_int len, padded_len;
965 u_int checksum, stored_checksum;
967 /* Check if input size is less than minimum packet size. */
968 if (buffer_len(&input) < 4 + 8)
970 /* Get length of incoming packet. */
971 cp = buffer_ptr(&input);
973 if (len < 1 + 2 + 2 || len > 256 * 1024)
974 packet_disconnect("Bad packet length %u.", len);
975 padded_len = (len + 8) & ~7;
977 /* Check if the packet has been entirely received. */
978 if (buffer_len(&input) < 4 + padded_len)
981 /* The entire packet is in buffer. */
983 /* Consume packet length. */
984 buffer_consume(&input, 4);
987 * Cryptographic attack detector for ssh
988 * (C)1998 CORE-SDI, Buenos Aires Argentina
989 * Ariel Futoransky(futo@core-sdi.com)
991 if (!receive_context.plaintext &&
992 detect_attack(buffer_ptr(&input), padded_len) == DEATTACK_DETECTED)
993 packet_disconnect("crc32 compensation attack: network attack detected");
995 /* Decrypt data to incoming_packet. */
996 buffer_clear(&incoming_packet);
997 cp = buffer_append_space(&incoming_packet, padded_len);
998 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1000 buffer_consume(&input, padded_len);
1003 fprintf(stderr, "read_poll plain: ");
1004 buffer_dump(&incoming_packet);
1007 /* Compute packet checksum. */
1008 checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1009 buffer_len(&incoming_packet) - 4);
1012 buffer_consume(&incoming_packet, 8 - len % 8);
1014 /* Test check bytes. */
1015 if (len != buffer_len(&incoming_packet))
1016 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1017 len, buffer_len(&incoming_packet));
1019 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1020 stored_checksum = GET_32BIT(cp);
1021 if (checksum != stored_checksum)
1022 packet_disconnect("Corrupted check bytes on input.");
1023 buffer_consume_end(&incoming_packet, 4);
1025 if (packet_compression) {
1026 buffer_clear(&compression_buffer);
1027 buffer_uncompress(&incoming_packet, &compression_buffer);
1028 buffer_clear(&incoming_packet);
1029 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1030 buffer_len(&compression_buffer));
1032 type = buffer_get_char(&incoming_packet);
1033 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1034 packet_disconnect("Invalid ssh1 packet type: %d", type);
1039 packet_read_poll2(u_int32_t *seqnr_p)
1041 static u_int packet_length = 0;
1043 u_char *macbuf, *cp, type;
1044 u_int maclen, block_size;
1049 if (newkeys[MODE_IN] != NULL) {
1050 enc = &newkeys[MODE_IN]->enc;
1051 mac = &newkeys[MODE_IN]->mac;
1052 comp = &newkeys[MODE_IN]->comp;
1054 maclen = mac && mac->enabled ? mac->mac_len : 0;
1055 block_size = enc ? enc->block_size : 8;
1057 if (packet_length == 0) {
1059 * check if input size is less than the cipher block size,
1060 * decrypt first block and extract length of incoming packet
1062 if (buffer_len(&input) < block_size)
1063 return SSH_MSG_NONE;
1064 buffer_clear(&incoming_packet);
1065 cp = buffer_append_space(&incoming_packet, block_size);
1066 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1068 cp = buffer_ptr(&incoming_packet);
1069 packet_length = GET_32BIT(cp);
1070 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1072 buffer_dump(&incoming_packet);
1074 packet_disconnect("Bad packet length %u.", packet_length);
1076 DBG(debug("input: packet len %u", packet_length+4));
1077 buffer_consume(&input, block_size);
1079 /* we have a partial packet of block_size bytes */
1080 need = 4 + packet_length - block_size;
1081 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1083 if (need % block_size != 0)
1084 fatal("padding error: need %d block %d mod %d",
1085 need, block_size, need % block_size);
1087 * check if the entire packet has been received and
1088 * decrypt into incoming_packet
1090 if (buffer_len(&input) < need + maclen)
1091 return SSH_MSG_NONE;
1093 fprintf(stderr, "read_poll enc/full: ");
1094 buffer_dump(&input);
1096 cp = buffer_append_space(&incoming_packet, need);
1097 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1098 buffer_consume(&input, need);
1100 * compute MAC over seqnr and packet,
1101 * increment sequence number for incoming packet
1103 if (mac && mac->enabled) {
1104 macbuf = mac_compute(mac, p_read.seqnr,
1105 buffer_ptr(&incoming_packet),
1106 buffer_len(&incoming_packet));
1107 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1108 packet_disconnect("Corrupted MAC on input.");
1109 DBG(debug("MAC #%d ok", p_read.seqnr));
1110 buffer_consume(&input, mac->mac_len);
1112 if (seqnr_p != NULL)
1113 *seqnr_p = p_read.seqnr;
1114 if (++p_read.seqnr == 0)
1115 logit("incoming seqnr wraps around");
1116 if (++p_read.packets == 0)
1117 if (!(datafellows & SSH_BUG_NOREKEY))
1118 fatal("XXX too many packets with same key");
1119 p_read.blocks += (packet_length + 4) / block_size;
1122 cp = buffer_ptr(&incoming_packet);
1124 DBG(debug("input: padlen %d", padlen));
1126 packet_disconnect("Corrupted padlen %d on input.", padlen);
1128 /* skip packet size + padlen, discard padding */
1129 buffer_consume(&incoming_packet, 4 + 1);
1130 buffer_consume_end(&incoming_packet, padlen);
1132 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1133 if (comp && comp->enabled) {
1134 buffer_clear(&compression_buffer);
1135 buffer_uncompress(&incoming_packet, &compression_buffer);
1136 buffer_clear(&incoming_packet);
1137 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1138 buffer_len(&compression_buffer));
1139 DBG(debug("input: len after de-compress %d",
1140 buffer_len(&incoming_packet)));
1143 * get packet type, implies consume.
1144 * return length of payload (without type field)
1146 type = buffer_get_char(&incoming_packet);
1147 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1148 packet_disconnect("Invalid ssh2 packet type: %d", type);
1149 if (type == SSH2_MSG_NEWKEYS)
1150 set_newkeys(MODE_IN);
1151 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1152 packet_enable_delayed_compress();
1154 fprintf(stderr, "read/plain[%d]:\r\n", type);
1155 buffer_dump(&incoming_packet);
1157 /* reset for next packet */
1163 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1165 u_int reason, seqnr;
1171 type = packet_read_poll2(seqnr_p);
1173 DBG(debug("received packet type %d", type));
1175 case SSH2_MSG_IGNORE:
1177 case SSH2_MSG_DEBUG:
1179 msg = packet_get_string(NULL);
1180 debug("Remote: %.900s", msg);
1182 msg = packet_get_string(NULL);
1185 case SSH2_MSG_DISCONNECT:
1186 reason = packet_get_int();
1187 msg = packet_get_string(NULL);
1188 logit("Received disconnect from %s: %u: %.400s",
1189 get_remote_ipaddr(), reason, msg);
1193 case SSH2_MSG_UNIMPLEMENTED:
1194 seqnr = packet_get_int();
1195 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1202 type = packet_read_poll1();
1204 case SSH_MSG_IGNORE:
1207 msg = packet_get_string(NULL);
1208 debug("Remote: %.900s", msg);
1211 case SSH_MSG_DISCONNECT:
1212 msg = packet_get_string(NULL);
1213 logit("Received disconnect from %s: %.400s",
1214 get_remote_ipaddr(), msg);
1220 DBG(debug("received packet type %d", type));
1228 packet_read_poll(void)
1230 return packet_read_poll_seqnr(NULL);
1234 * Buffers the given amount of input characters. This is intended to be used
1235 * together with packet_read_poll.
1239 packet_process_incoming(const char *buf, u_int len)
1241 buffer_append(&input, buf, len);
1244 /* Returns a character from the packet. */
1247 packet_get_char(void)
1251 buffer_get(&incoming_packet, &ch, 1);
1255 /* Returns an integer from the packet data. */
1258 packet_get_int(void)
1260 return buffer_get_int(&incoming_packet);
1264 * Returns an arbitrary precision integer from the packet data. The integer
1265 * must have been initialized before this call.
1269 packet_get_bignum(BIGNUM * value)
1271 buffer_get_bignum(&incoming_packet, value);
1275 packet_get_bignum2(BIGNUM * value)
1277 buffer_get_bignum2(&incoming_packet, value);
1281 packet_get_raw(u_int *length_ptr)
1283 u_int bytes = buffer_len(&incoming_packet);
1285 if (length_ptr != NULL)
1286 *length_ptr = bytes;
1287 return buffer_ptr(&incoming_packet);
1291 packet_remaining(void)
1293 return buffer_len(&incoming_packet);
1297 * Returns a string from the packet data. The string is allocated using
1298 * xmalloc; it is the responsibility of the calling program to free it when
1299 * no longer needed. The length_ptr argument may be NULL, or point to an
1300 * integer into which the length of the string is stored.
1304 packet_get_string(u_int *length_ptr)
1306 return buffer_get_string(&incoming_packet, length_ptr);
1310 * Sends a diagnostic message from the server to the client. This message
1311 * can be sent at any time (but not while constructing another message). The
1312 * message is printed immediately, but only if the client is being executed
1313 * in verbose mode. These messages are primarily intended to ease debugging
1314 * authentication problems. The length of the formatted message must not
1315 * exceed 1024 bytes. This will automatically call packet_write_wait.
1319 packet_send_debug(const char *fmt,...)
1324 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1327 va_start(args, fmt);
1328 vsnprintf(buf, sizeof(buf), fmt, args);
1332 packet_start(SSH2_MSG_DEBUG);
1333 packet_put_char(0); /* bool: always display */
1334 packet_put_cstring(buf);
1335 packet_put_cstring("");
1337 packet_start(SSH_MSG_DEBUG);
1338 packet_put_cstring(buf);
1341 packet_write_wait();
1345 * Logs the error plus constructs and sends a disconnect packet, closes the
1346 * connection, and exits. This function never returns. The error message
1347 * should not contain a newline. The length of the formatted message must
1348 * not exceed 1024 bytes.
1352 packet_disconnect(const char *fmt,...)
1356 static int disconnecting = 0;
1358 if (disconnecting) /* Guard against recursive invocations. */
1359 fatal("packet_disconnect called recursively.");
1363 * Format the message. Note that the caller must make sure the
1364 * message is of limited size.
1366 va_start(args, fmt);
1367 vsnprintf(buf, sizeof(buf), fmt, args);
1370 /* Display the error locally */
1371 logit("Disconnecting: %.100s", buf);
1373 /* Send the disconnect message to the other side, and wait for it to get sent. */
1375 packet_start(SSH2_MSG_DISCONNECT);
1376 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1377 packet_put_cstring(buf);
1378 packet_put_cstring("");
1380 packet_start(SSH_MSG_DISCONNECT);
1381 packet_put_cstring(buf);
1384 packet_write_wait();
1386 /* Stop listening for connections. */
1387 channel_close_all();
1389 /* Close the connection. */
1394 /* Checks if there is any buffered output, and tries to write some of the output. */
1397 packet_write_poll(void)
1399 int len = buffer_len(&output);
1402 len = write(connection_out, buffer_ptr(&output), len);
1404 if (errno == EAGAIN)
1407 fatal("Write failed: %.100s", strerror(errno));
1409 buffer_consume(&output, len);
1414 * Calls packet_write_poll repeatedly until all pending output data has been
1419 packet_write_wait(void)
1423 setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1425 packet_write_poll();
1426 while (packet_have_data_to_write()) {
1427 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1429 FD_SET(connection_out, setp);
1430 while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 &&
1431 (errno == EAGAIN || errno == EINTR))
1433 packet_write_poll();
1438 /* Returns true if there is buffered data to write to the connection. */
1441 packet_have_data_to_write(void)
1443 return buffer_len(&output) != 0;
1446 /* Returns true if there is not too much data to write to the connection. */
1449 packet_not_very_much_data_to_write(void)
1451 if (interactive_mode)
1452 return buffer_len(&output) < 16384;
1454 return buffer_len(&output) < 128 * 1024;
1459 packet_set_tos(int interactive)
1461 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1462 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1464 if (!packet_connection_is_on_socket() ||
1465 !packet_connection_is_ipv4())
1467 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1469 error("setsockopt IP_TOS %d: %.100s:",
1470 tos, strerror(errno));
1474 /* Informs that the current session is interactive. Sets IP flags for that. */
1477 packet_set_interactive(int interactive)
1479 static int called = 0;
1485 /* Record that we are in interactive mode. */
1486 interactive_mode = interactive;
1488 /* Only set socket options if using a socket. */
1489 if (!packet_connection_is_on_socket())
1491 set_nodelay(connection_in);
1492 packet_set_tos(interactive);
1495 /* Returns true if the current connection is interactive. */
1498 packet_is_interactive(void)
1500 return interactive_mode;
1504 packet_set_maxsize(u_int s)
1506 static int called = 0;
1509 logit("packet_set_maxsize: called twice: old %d new %d",
1510 max_packet_size, s);
1513 if (s < 4 * 1024 || s > 1024 * 1024) {
1514 logit("packet_set_maxsize: bad size %d", s);
1518 debug("packet_set_maxsize: setting to %d", s);
1519 max_packet_size = s;
1523 /* roundup current message to pad bytes */
1525 packet_add_padding(u_char pad)
1531 * 9.2. Ignored Data Message
1533 * byte SSH_MSG_IGNORE
1536 * All implementations MUST understand (and ignore) this message at any
1537 * time (after receiving the protocol version). No implementation is
1538 * required to send them. This message can be used as an additional
1539 * protection measure against advanced traffic analysis techniques.
1542 packet_send_ignore(int nbytes)
1547 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1548 packet_put_int(nbytes);
1549 for (i = 0; i < nbytes; i++) {
1552 packet_put_char(rnd & 0xff);
1557 #define MAX_PACKETS (1U<<31)
1559 packet_need_rekeying(void)
1561 if (datafellows & SSH_BUG_NOREKEY)
1564 (p_send.packets > MAX_PACKETS) ||
1565 (p_read.packets > MAX_PACKETS) ||
1566 (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1567 (max_blocks_in && (p_read.blocks > max_blocks_in));
1571 packet_set_rekey_limit(u_int32_t bytes)
1573 rekey_limit = bytes;
1577 packet_set_server(void)
1583 packet_set_authenticated(void)
1585 after_authentication = 1;