1 /* $OpenBSD: packet.c,v 1.157 2008/07/10 18:08:11 markus 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 <sys/types.h>
43 #include "openbsd-compat/sys-queue.h"
44 #include <sys/param.h>
45 #include <sys/socket.h>
46 #ifdef HAVE_SYS_TIME_H
47 # include <sys/time.h>
50 #include <netinet/in.h>
51 #include <netinet/ip.h>
52 #include <arpa/inet.h>
88 * This variable contains the file descriptors used for communicating with
89 * the other side. connection_in is used for reading; connection_out for
90 * writing. These can be the same descriptor, in which case it is assumed to
93 static int connection_in = -1;
94 static int connection_out = -1;
96 /* Protocol flags for the remote side. */
97 static u_int remote_protocol_flags = 0;
99 /* Encryption context for receiving data. This is only used for decryption. */
100 static CipherContext receive_context;
102 /* Encryption context for sending data. This is only used for encryption. */
103 static CipherContext send_context;
105 /* Buffer for raw input data from the socket. */
108 /* Buffer for raw output data going to the socket. */
111 /* Buffer for the partial outgoing packet being constructed. */
112 static Buffer outgoing_packet;
114 /* Buffer for the incoming packet currently being processed. */
115 static Buffer incoming_packet;
117 /* Scratch buffer for packet compression/decompression. */
118 static Buffer compression_buffer;
119 static int compression_buffer_ready = 0;
121 /* Flag indicating whether packet compression/decompression is enabled. */
122 static int packet_compression = 0;
124 /* default maximum packet size */
125 u_int max_packet_size = 32768;
127 /* Flag indicating whether this module has been initialized. */
128 static int initialized = 0;
130 /* Set to true if the connection is interactive. */
131 static int interactive_mode = 0;
133 /* Set to true if we are the server side. */
134 static int server_side = 0;
136 /* Set to true if we are authenticated. */
137 static int after_authentication = 0;
139 int keep_alive_timeouts = 0;
141 /* Set to the maximum time that we will wait to send or receive a packet */
142 static int packet_timeout_ms = -1;
144 /* Session key information for Encryption and MAC */
145 Newkeys *newkeys[MODE_MAX];
146 static struct packet_state {
153 static u_int64_t max_blocks_in, max_blocks_out;
154 static u_int32_t rekey_limit;
156 /* Session key for protocol v1 */
157 static u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
158 static u_int ssh1_keylen;
160 /* roundup current message to extra_pad bytes */
161 static u_char extra_pad = 0;
164 TAILQ_ENTRY(packet) next;
168 TAILQ_HEAD(, packet) outgoing;
171 * Sets the descriptors used for communication. Disables encryption until
172 * packet_set_encryption_key is called.
175 packet_set_connection(int fd_in, int fd_out)
177 Cipher *none = cipher_by_name("none");
180 fatal("packet_set_connection: cannot load cipher 'none'");
181 connection_in = fd_in;
182 connection_out = fd_out;
183 cipher_init(&send_context, none, (const u_char *)"",
184 0, NULL, 0, CIPHER_ENCRYPT);
185 cipher_init(&receive_context, none, (const u_char *)"",
186 0, NULL, 0, CIPHER_DECRYPT);
187 newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL;
191 buffer_init(&output);
192 buffer_init(&outgoing_packet);
193 buffer_init(&incoming_packet);
194 TAILQ_INIT(&outgoing);
195 p_send.packets = p_read.packets = 0;
200 packet_set_timeout(int timeout, int count)
202 if (timeout == 0 || count == 0) {
203 packet_timeout_ms = -1;
206 if ((INT_MAX / 1000) / count < timeout)
207 packet_timeout_ms = INT_MAX;
209 packet_timeout_ms = timeout * count * 1000;
212 /* Returns 1 if remote host is connected via socket, 0 if not. */
215 packet_connection_is_on_socket(void)
217 struct sockaddr_storage from, to;
218 socklen_t fromlen, tolen;
220 /* filedescriptors in and out are the same, so it's a socket */
221 if (connection_in == connection_out)
223 fromlen = sizeof(from);
224 memset(&from, 0, sizeof(from));
225 if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0)
228 memset(&to, 0, sizeof(to));
229 if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0)
231 if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
233 if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
239 * Exports an IV from the CipherContext required to export the key
240 * state back from the unprivileged child to the privileged parent
245 packet_get_keyiv(int mode, u_char *iv, u_int len)
249 if (mode == MODE_OUT)
252 cc = &receive_context;
254 cipher_get_keyiv(cc, iv, len);
258 packet_get_keycontext(int mode, u_char *dat)
262 if (mode == MODE_OUT)
265 cc = &receive_context;
267 return (cipher_get_keycontext(cc, dat));
271 packet_set_keycontext(int mode, u_char *dat)
275 if (mode == MODE_OUT)
278 cc = &receive_context;
280 cipher_set_keycontext(cc, dat);
284 packet_get_keyiv_len(int mode)
288 if (mode == MODE_OUT)
291 cc = &receive_context;
293 return (cipher_get_keyiv_len(cc));
297 packet_set_iv(int mode, u_char *dat)
301 if (mode == MODE_OUT)
304 cc = &receive_context;
306 cipher_set_keyiv(cc, dat);
310 packet_get_ssh1_cipher(void)
312 return (cipher_get_number(receive_context.cipher));
316 packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks, u_int32_t *packets,
319 struct packet_state *state;
321 state = (mode == MODE_IN) ? &p_read : &p_send;
323 *seqnr = state->seqnr;
325 *blocks = state->blocks;
327 *packets = state->packets;
329 *bytes = state->bytes;
333 packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
336 struct packet_state *state;
338 state = (mode == MODE_IN) ? &p_read : &p_send;
339 state->seqnr = seqnr;
340 state->blocks = blocks;
341 state->packets = packets;
342 state->bytes = bytes;
345 /* returns 1 if connection is via ipv4 */
348 packet_connection_is_ipv4(void)
350 struct sockaddr_storage to;
351 socklen_t tolen = sizeof(to);
353 memset(&to, 0, sizeof(to));
354 if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0)
356 if (to.ss_family == AF_INET)
359 if (to.ss_family == AF_INET6 &&
360 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
366 /* Sets the connection into non-blocking mode. */
369 packet_set_nonblocking(void)
371 /* Set the socket into non-blocking mode. */
372 set_nonblock(connection_in);
374 if (connection_out != connection_in)
375 set_nonblock(connection_out);
378 /* Returns the socket used for reading. */
381 packet_get_connection_in(void)
383 return connection_in;
386 /* Returns the descriptor used for writing. */
389 packet_get_connection_out(void)
391 return connection_out;
394 /* Closes the connection and clears and frees internal data structures. */
402 if (connection_in == connection_out) {
403 shutdown(connection_out, SHUT_RDWR);
404 close(connection_out);
406 close(connection_in);
407 close(connection_out);
410 buffer_free(&output);
411 buffer_free(&outgoing_packet);
412 buffer_free(&incoming_packet);
413 if (compression_buffer_ready) {
414 buffer_free(&compression_buffer);
415 buffer_compress_uninit();
417 cipher_cleanup(&send_context);
418 cipher_cleanup(&receive_context);
421 /* Sets remote side protocol flags. */
424 packet_set_protocol_flags(u_int protocol_flags)
426 remote_protocol_flags = protocol_flags;
429 /* Returns the remote protocol flags set earlier by the above function. */
432 packet_get_protocol_flags(void)
434 return remote_protocol_flags;
438 * Starts packet compression from the next packet on in both directions.
439 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
443 packet_init_compression(void)
445 if (compression_buffer_ready == 1)
447 compression_buffer_ready = 1;
448 buffer_init(&compression_buffer);
452 packet_start_compression(int level)
454 if (packet_compression && !compat20)
455 fatal("Compression already enabled.");
456 packet_compression = 1;
457 packet_init_compression();
458 buffer_compress_init_send(level);
459 buffer_compress_init_recv();
463 * Causes any further packets to be encrypted using the given key. The same
464 * key is used for both sending and reception. However, both directions are
465 * encrypted independently of each other.
469 packet_set_encryption_key(const u_char *key, u_int keylen,
472 Cipher *cipher = cipher_by_number(number);
475 fatal("packet_set_encryption_key: unknown cipher number %d", number);
477 fatal("packet_set_encryption_key: keylen too small: %d", keylen);
478 if (keylen > SSH_SESSION_KEY_LENGTH)
479 fatal("packet_set_encryption_key: keylen too big: %d", keylen);
480 memcpy(ssh1_key, key, keylen);
481 ssh1_keylen = keylen;
482 cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT);
483 cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT);
487 packet_get_encryption_key(u_char *key)
490 return (ssh1_keylen);
491 memcpy(key, ssh1_key, ssh1_keylen);
492 return (ssh1_keylen);
495 /* Start constructing a packet to send. */
497 packet_start(u_char type)
502 DBG(debug("packet_start[%d]", type));
503 len = compat20 ? 6 : 9;
504 memset(buf, 0, len - 1);
506 buffer_clear(&outgoing_packet);
507 buffer_append(&outgoing_packet, buf, len);
510 /* Append payload. */
512 packet_put_char(int value)
516 buffer_append(&outgoing_packet, &ch, 1);
520 packet_put_int(u_int value)
522 buffer_put_int(&outgoing_packet, value);
526 packet_put_string(const void *buf, u_int len)
528 buffer_put_string(&outgoing_packet, buf, len);
532 packet_put_cstring(const char *str)
534 buffer_put_cstring(&outgoing_packet, str);
538 packet_put_raw(const void *buf, u_int len)
540 buffer_append(&outgoing_packet, buf, len);
544 packet_put_bignum(BIGNUM * value)
546 buffer_put_bignum(&outgoing_packet, value);
550 packet_put_bignum2(BIGNUM * value)
552 buffer_put_bignum2(&outgoing_packet, value);
556 * Finalizes and sends the packet. If the encryption key has been set,
557 * encrypts the packet before sending.
569 * If using packet compression, compress the payload of the outgoing
572 if (packet_compression) {
573 buffer_clear(&compression_buffer);
575 buffer_consume(&outgoing_packet, 8);
577 buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8);
578 buffer_compress(&outgoing_packet, &compression_buffer);
579 buffer_clear(&outgoing_packet);
580 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
581 buffer_len(&compression_buffer));
583 /* Compute packet length without padding (add checksum, remove padding). */
584 len = buffer_len(&outgoing_packet) + 4 - 8;
586 /* Insert padding. Initialized to zero in packet_start1() */
587 padding = 8 - len % 8;
588 if (!send_context.plaintext) {
589 cp = buffer_ptr(&outgoing_packet);
590 for (i = 0; i < padding; i++) {
593 cp[7 - i] = rnd & 0xff;
597 buffer_consume(&outgoing_packet, 8 - padding);
599 /* Add check bytes. */
600 checksum = ssh_crc32(buffer_ptr(&outgoing_packet),
601 buffer_len(&outgoing_packet));
602 put_u32(buf, checksum);
603 buffer_append(&outgoing_packet, buf, 4);
606 fprintf(stderr, "packet_send plain: ");
607 buffer_dump(&outgoing_packet);
610 /* Append to output. */
612 buffer_append(&output, buf, 4);
613 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
614 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
615 buffer_len(&outgoing_packet));
618 fprintf(stderr, "encrypted: ");
619 buffer_dump(&output);
622 p_send.bytes += len + buffer_len(&outgoing_packet);
623 buffer_clear(&outgoing_packet);
626 * Note that the packet is now only buffered in output. It won't be
627 * actually sent until packet_write_wait or packet_write_poll is
633 set_newkeys(int mode)
639 u_int64_t *max_blocks;
642 debug2("set_newkeys: mode %d", mode);
644 if (mode == MODE_OUT) {
646 crypt_type = CIPHER_ENCRYPT;
647 p_send.packets = p_send.blocks = 0;
648 max_blocks = &max_blocks_out;
650 cc = &receive_context;
651 crypt_type = CIPHER_DECRYPT;
652 p_read.packets = p_read.blocks = 0;
653 max_blocks = &max_blocks_in;
655 if (newkeys[mode] != NULL) {
656 debug("set_newkeys: rekeying");
658 enc = &newkeys[mode]->enc;
659 mac = &newkeys[mode]->mac;
660 comp = &newkeys[mode]->comp;
668 xfree(newkeys[mode]);
670 newkeys[mode] = kex_get_newkeys(mode);
671 if (newkeys[mode] == NULL)
672 fatal("newkeys: no keys for mode %d", mode);
673 enc = &newkeys[mode]->enc;
674 mac = &newkeys[mode]->mac;
675 comp = &newkeys[mode]->comp;
676 if (mac_init(mac) == 0)
678 DBG(debug("cipher_init_context: %d", mode));
679 cipher_init(cc, enc->cipher, enc->key, enc->key_len,
680 enc->iv, enc->block_size, crypt_type);
681 /* Deleting the keys does not gain extra security */
682 /* memset(enc->iv, 0, enc->block_size);
683 memset(enc->key, 0, enc->key_len);
684 memset(mac->key, 0, mac->key_len); */
685 if ((comp->type == COMP_ZLIB ||
686 (comp->type == COMP_DELAYED && after_authentication)) &&
687 comp->enabled == 0) {
688 packet_init_compression();
689 if (mode == MODE_OUT)
690 buffer_compress_init_send(6);
692 buffer_compress_init_recv();
696 * The 2^(blocksize*2) limit is too expensive for 3DES,
697 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
699 if (enc->block_size >= 16)
700 *max_blocks = (u_int64_t)1 << (enc->block_size*2);
702 *max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
704 *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size);
708 * Delayed compression for SSH2 is enabled after authentication:
709 * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
710 * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
713 packet_enable_delayed_compress(void)
719 * Remember that we are past the authentication step, so rekeying
720 * with COMP_DELAYED will turn on compression immediately.
722 after_authentication = 1;
723 for (mode = 0; mode < MODE_MAX; mode++) {
724 /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
725 if (newkeys[mode] == NULL)
727 comp = &newkeys[mode]->comp;
728 if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
729 packet_init_compression();
730 if (mode == MODE_OUT)
731 buffer_compress_init_send(6);
733 buffer_compress_init_recv();
740 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
743 packet_send2_wrapped(void)
745 u_char type, *cp, *macbuf = NULL;
747 u_int packet_length = 0;
755 if (newkeys[MODE_OUT] != NULL) {
756 enc = &newkeys[MODE_OUT]->enc;
757 mac = &newkeys[MODE_OUT]->mac;
758 comp = &newkeys[MODE_OUT]->comp;
760 block_size = enc ? enc->block_size : 8;
762 cp = buffer_ptr(&outgoing_packet);
766 fprintf(stderr, "plain: ");
767 buffer_dump(&outgoing_packet);
770 if (comp && comp->enabled) {
771 len = buffer_len(&outgoing_packet);
772 /* skip header, compress only payload */
773 buffer_consume(&outgoing_packet, 5);
774 buffer_clear(&compression_buffer);
775 buffer_compress(&outgoing_packet, &compression_buffer);
776 buffer_clear(&outgoing_packet);
777 buffer_append(&outgoing_packet, "\0\0\0\0\0", 5);
778 buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer),
779 buffer_len(&compression_buffer));
780 DBG(debug("compression: raw %d compressed %d", len,
781 buffer_len(&outgoing_packet)));
784 /* sizeof (packet_len + pad_len + payload) */
785 len = buffer_len(&outgoing_packet);
788 * calc size of padding, alloc space, get random data,
789 * minimum padding is 4 bytes
791 padlen = block_size - (len % block_size);
793 padlen += block_size;
795 /* will wrap if extra_pad+padlen > 255 */
796 extra_pad = roundup(extra_pad, block_size);
797 pad = extra_pad - ((len + padlen) % extra_pad);
798 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
799 pad, len, padlen, extra_pad);
803 cp = buffer_append_space(&outgoing_packet, padlen);
804 if (enc && !send_context.plaintext) {
806 for (i = 0; i < padlen; i++) {
814 memset(cp, 0, padlen);
816 /* packet_length includes payload, padding and padding length field */
817 packet_length = buffer_len(&outgoing_packet) - 4;
818 cp = buffer_ptr(&outgoing_packet);
819 put_u32(cp, packet_length);
821 DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen));
823 /* compute MAC over seqnr and packet(length fields, payload, padding) */
824 if (mac && mac->enabled) {
825 macbuf = mac_compute(mac, p_send.seqnr,
826 buffer_ptr(&outgoing_packet),
827 buffer_len(&outgoing_packet));
828 DBG(debug("done calc MAC out #%d", p_send.seqnr));
830 /* encrypt packet and append to output buffer. */
831 cp = buffer_append_space(&output, buffer_len(&outgoing_packet));
832 cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet),
833 buffer_len(&outgoing_packet));
834 /* append unencrypted MAC */
835 if (mac && mac->enabled)
836 buffer_append(&output, macbuf, mac->mac_len);
838 fprintf(stderr, "encrypted: ");
839 buffer_dump(&output);
841 /* increment sequence number for outgoing packets */
842 if (++p_send.seqnr == 0)
843 logit("outgoing seqnr wraps around");
844 if (++p_send.packets == 0)
845 if (!(datafellows & SSH_BUG_NOREKEY))
846 fatal("XXX too many packets with same key");
847 p_send.blocks += (packet_length + 4) / block_size;
848 p_send.bytes += packet_length + 4;
849 buffer_clear(&outgoing_packet);
851 if (type == SSH2_MSG_NEWKEYS)
852 set_newkeys(MODE_OUT);
853 else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side)
854 packet_enable_delayed_compress();
860 static int rekeying = 0;
864 cp = buffer_ptr(&outgoing_packet);
867 /* during rekeying we can only send key exchange messages */
869 if (!((type >= SSH2_MSG_TRANSPORT_MIN) &&
870 (type <= SSH2_MSG_TRANSPORT_MAX))) {
871 debug("enqueue packet: %u", type);
872 p = xmalloc(sizeof(*p));
874 memcpy(&p->payload, &outgoing_packet, sizeof(Buffer));
875 buffer_init(&outgoing_packet);
876 TAILQ_INSERT_TAIL(&outgoing, p, next);
881 /* rekeying starts with sending KEXINIT */
882 if (type == SSH2_MSG_KEXINIT)
885 packet_send2_wrapped();
887 /* after a NEWKEYS message we can send the complete queue */
888 if (type == SSH2_MSG_NEWKEYS) {
890 while ((p = TAILQ_FIRST(&outgoing))) {
892 debug("dequeue packet: %u", type);
893 buffer_free(&outgoing_packet);
894 memcpy(&outgoing_packet, &p->payload,
896 TAILQ_REMOVE(&outgoing, p, next);
898 packet_send2_wrapped();
910 DBG(debug("packet_send done"));
914 * Waits until a packet has been received, and returns its type. Note that
915 * no other data is processed until this returns, so this function should not
916 * be used during the interactive session.
920 packet_read_seqnr(u_int32_t *seqnr_p)
922 int type, len, ret, ms_remain;
925 struct timeval timeout, start, *timeoutp = NULL;
927 DBG(debug("packet_read()"));
929 setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS),
932 /* Since we are blocking, ensure that all written packets have been sent. */
935 /* Stay in the loop until we have received a complete packet. */
937 /* Try to read a packet from the buffer. */
938 type = packet_read_poll_seqnr(seqnr_p);
940 type == SSH_SMSG_SUCCESS
941 || type == SSH_SMSG_FAILURE
942 || type == SSH_CMSG_EOF
943 || type == SSH_CMSG_EXIT_CONFIRMATION))
945 /* If we got a packet, return it. */
946 if (type != SSH_MSG_NONE) {
951 * Otherwise, wait for some data to arrive, add it to the
952 * buffer, and try again.
954 memset(setp, 0, howmany(connection_in + 1, NFDBITS) *
956 FD_SET(connection_in, setp);
958 if (packet_timeout_ms > 0) {
959 ms_remain = packet_timeout_ms;
962 /* Wait for some data to arrive. */
964 if (packet_timeout_ms != -1) {
965 ms_to_timeval(&timeout, ms_remain);
966 gettimeofday(&start, NULL);
968 if ((ret = select(connection_in + 1, setp, NULL,
969 NULL, timeoutp)) >= 0)
971 if (errno != EAGAIN && errno != EINTR &&
972 errno != EWOULDBLOCK)
974 if (packet_timeout_ms == -1)
976 ms_subtract_diff(&start, &ms_remain);
977 if (ms_remain <= 0) {
983 logit("Connection to %.200s timed out while "
984 "waiting to read", get_remote_ipaddr());
987 /* Read data from the socket. */
988 len = read(connection_in, buf, sizeof(buf));
990 logit("Connection closed by %.200s", get_remote_ipaddr());
994 fatal("Read from socket failed: %.100s", strerror(errno));
995 /* Append it to the buffer. */
996 packet_process_incoming(buf, len);
1004 return packet_read_seqnr(NULL);
1008 * Waits until a packet has been received, verifies that its type matches
1009 * that given, and gives a fatal error and exits if there is a mismatch.
1013 packet_read_expect(int expected_type)
1017 type = packet_read();
1018 if (type != expected_type)
1019 packet_disconnect("Protocol error: expected packet type %d, got %d",
1020 expected_type, type);
1023 /* Checks if a full packet is available in the data received so far via
1024 * packet_process_incoming. If so, reads the packet; otherwise returns
1025 * SSH_MSG_NONE. This does not wait for data from the connection.
1027 * SSH_MSG_DISCONNECT is handled specially here. Also,
1028 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
1033 packet_read_poll1(void)
1035 u_int len, padded_len;
1037 u_int checksum, stored_checksum;
1039 /* Check if input size is less than minimum packet size. */
1040 if (buffer_len(&input) < 4 + 8)
1041 return SSH_MSG_NONE;
1042 /* Get length of incoming packet. */
1043 cp = buffer_ptr(&input);
1045 if (len < 1 + 2 + 2 || len > 256 * 1024)
1046 packet_disconnect("Bad packet length %u.", len);
1047 padded_len = (len + 8) & ~7;
1049 /* Check if the packet has been entirely received. */
1050 if (buffer_len(&input) < 4 + padded_len)
1051 return SSH_MSG_NONE;
1053 /* The entire packet is in buffer. */
1055 /* Consume packet length. */
1056 buffer_consume(&input, 4);
1059 * Cryptographic attack detector for ssh
1060 * (C)1998 CORE-SDI, Buenos Aires Argentina
1061 * Ariel Futoransky(futo@core-sdi.com)
1063 if (!receive_context.plaintext) {
1064 switch (detect_attack(buffer_ptr(&input), padded_len)) {
1065 case DEATTACK_DETECTED:
1066 packet_disconnect("crc32 compensation attack: "
1067 "network attack detected");
1068 case DEATTACK_DOS_DETECTED:
1069 packet_disconnect("deattack denial of "
1070 "service detected");
1074 /* Decrypt data to incoming_packet. */
1075 buffer_clear(&incoming_packet);
1076 cp = buffer_append_space(&incoming_packet, padded_len);
1077 cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len);
1079 buffer_consume(&input, padded_len);
1082 fprintf(stderr, "read_poll plain: ");
1083 buffer_dump(&incoming_packet);
1086 /* Compute packet checksum. */
1087 checksum = ssh_crc32(buffer_ptr(&incoming_packet),
1088 buffer_len(&incoming_packet) - 4);
1091 buffer_consume(&incoming_packet, 8 - len % 8);
1093 /* Test check bytes. */
1094 if (len != buffer_len(&incoming_packet))
1095 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
1096 len, buffer_len(&incoming_packet));
1098 cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4;
1099 stored_checksum = get_u32(cp);
1100 if (checksum != stored_checksum)
1101 packet_disconnect("Corrupted check bytes on input.");
1102 buffer_consume_end(&incoming_packet, 4);
1104 if (packet_compression) {
1105 buffer_clear(&compression_buffer);
1106 buffer_uncompress(&incoming_packet, &compression_buffer);
1107 buffer_clear(&incoming_packet);
1108 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1109 buffer_len(&compression_buffer));
1112 p_read.bytes += padded_len + 4;
1113 type = buffer_get_char(&incoming_packet);
1114 if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
1115 packet_disconnect("Invalid ssh1 packet type: %d", type);
1120 packet_read_poll2(u_int32_t *seqnr_p)
1122 static u_int packet_length = 0;
1124 u_char *macbuf, *cp, type;
1125 u_int maclen, block_size;
1130 if (newkeys[MODE_IN] != NULL) {
1131 enc = &newkeys[MODE_IN]->enc;
1132 mac = &newkeys[MODE_IN]->mac;
1133 comp = &newkeys[MODE_IN]->comp;
1135 maclen = mac && mac->enabled ? mac->mac_len : 0;
1136 block_size = enc ? enc->block_size : 8;
1138 if (packet_length == 0) {
1140 * check if input size is less than the cipher block size,
1141 * decrypt first block and extract length of incoming packet
1143 if (buffer_len(&input) < block_size)
1144 return SSH_MSG_NONE;
1145 buffer_clear(&incoming_packet);
1146 cp = buffer_append_space(&incoming_packet, block_size);
1147 cipher_crypt(&receive_context, cp, buffer_ptr(&input),
1149 cp = buffer_ptr(&incoming_packet);
1150 packet_length = get_u32(cp);
1151 if (packet_length < 1 + 4 || packet_length > 256 * 1024) {
1153 buffer_dump(&incoming_packet);
1155 packet_disconnect("Bad packet length %u.", packet_length);
1157 DBG(debug("input: packet len %u", packet_length+4));
1158 buffer_consume(&input, block_size);
1160 /* we have a partial packet of block_size bytes */
1161 need = 4 + packet_length - block_size;
1162 DBG(debug("partial packet %d, need %d, maclen %d", block_size,
1164 if (need % block_size != 0)
1165 fatal("padding error: need %d block %d mod %d",
1166 need, block_size, need % block_size);
1168 * check if the entire packet has been received and
1169 * decrypt into incoming_packet
1171 if (buffer_len(&input) < need + maclen)
1172 return SSH_MSG_NONE;
1174 fprintf(stderr, "read_poll enc/full: ");
1175 buffer_dump(&input);
1177 cp = buffer_append_space(&incoming_packet, need);
1178 cipher_crypt(&receive_context, cp, buffer_ptr(&input), need);
1179 buffer_consume(&input, need);
1181 * compute MAC over seqnr and packet,
1182 * increment sequence number for incoming packet
1184 if (mac && mac->enabled) {
1185 macbuf = mac_compute(mac, p_read.seqnr,
1186 buffer_ptr(&incoming_packet),
1187 buffer_len(&incoming_packet));
1188 if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0)
1189 packet_disconnect("Corrupted MAC on input.");
1190 DBG(debug("MAC #%d ok", p_read.seqnr));
1191 buffer_consume(&input, mac->mac_len);
1193 if (seqnr_p != NULL)
1194 *seqnr_p = p_read.seqnr;
1195 if (++p_read.seqnr == 0)
1196 logit("incoming seqnr wraps around");
1197 if (++p_read.packets == 0)
1198 if (!(datafellows & SSH_BUG_NOREKEY))
1199 fatal("XXX too many packets with same key");
1200 p_read.blocks += (packet_length + 4) / block_size;
1201 p_read.bytes += packet_length + 4;
1204 cp = buffer_ptr(&incoming_packet);
1206 DBG(debug("input: padlen %d", padlen));
1208 packet_disconnect("Corrupted padlen %d on input.", padlen);
1210 /* skip packet size + padlen, discard padding */
1211 buffer_consume(&incoming_packet, 4 + 1);
1212 buffer_consume_end(&incoming_packet, padlen);
1214 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet)));
1215 if (comp && comp->enabled) {
1216 buffer_clear(&compression_buffer);
1217 buffer_uncompress(&incoming_packet, &compression_buffer);
1218 buffer_clear(&incoming_packet);
1219 buffer_append(&incoming_packet, buffer_ptr(&compression_buffer),
1220 buffer_len(&compression_buffer));
1221 DBG(debug("input: len after de-compress %d",
1222 buffer_len(&incoming_packet)));
1225 * get packet type, implies consume.
1226 * return length of payload (without type field)
1228 type = buffer_get_char(&incoming_packet);
1229 if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
1230 packet_disconnect("Invalid ssh2 packet type: %d", type);
1231 if (type == SSH2_MSG_NEWKEYS)
1232 set_newkeys(MODE_IN);
1233 else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side)
1234 packet_enable_delayed_compress();
1236 fprintf(stderr, "read/plain[%d]:\r\n", type);
1237 buffer_dump(&incoming_packet);
1239 /* reset for next packet */
1245 packet_read_poll_seqnr(u_int32_t *seqnr_p)
1247 u_int reason, seqnr;
1253 type = packet_read_poll2(seqnr_p);
1255 keep_alive_timeouts = 0;
1256 DBG(debug("received packet type %d", type));
1259 case SSH2_MSG_IGNORE:
1260 debug3("Received SSH2_MSG_IGNORE");
1262 case SSH2_MSG_DEBUG:
1264 msg = packet_get_string(NULL);
1265 debug("Remote: %.900s", msg);
1267 msg = packet_get_string(NULL);
1270 case SSH2_MSG_DISCONNECT:
1271 reason = packet_get_int();
1272 msg = packet_get_string(NULL);
1273 logit("Received disconnect from %s: %u: %.400s",
1274 get_remote_ipaddr(), reason, msg);
1278 case SSH2_MSG_UNIMPLEMENTED:
1279 seqnr = packet_get_int();
1280 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1287 type = packet_read_poll1();
1289 case SSH_MSG_IGNORE:
1292 msg = packet_get_string(NULL);
1293 debug("Remote: %.900s", msg);
1296 case SSH_MSG_DISCONNECT:
1297 msg = packet_get_string(NULL);
1298 logit("Received disconnect from %s: %.400s",
1299 get_remote_ipaddr(), msg);
1304 DBG(debug("received packet type %d", type));
1312 packet_read_poll(void)
1314 return packet_read_poll_seqnr(NULL);
1318 * Buffers the given amount of input characters. This is intended to be used
1319 * together with packet_read_poll.
1323 packet_process_incoming(const char *buf, u_int len)
1325 buffer_append(&input, buf, len);
1328 /* Returns a character from the packet. */
1331 packet_get_char(void)
1335 buffer_get(&incoming_packet, &ch, 1);
1339 /* Returns an integer from the packet data. */
1342 packet_get_int(void)
1344 return buffer_get_int(&incoming_packet);
1348 * Returns an arbitrary precision integer from the packet data. The integer
1349 * must have been initialized before this call.
1353 packet_get_bignum(BIGNUM * value)
1355 buffer_get_bignum(&incoming_packet, value);
1359 packet_get_bignum2(BIGNUM * value)
1361 buffer_get_bignum2(&incoming_packet, value);
1365 packet_get_raw(u_int *length_ptr)
1367 u_int bytes = buffer_len(&incoming_packet);
1369 if (length_ptr != NULL)
1370 *length_ptr = bytes;
1371 return buffer_ptr(&incoming_packet);
1375 packet_remaining(void)
1377 return buffer_len(&incoming_packet);
1381 * Returns a string from the packet data. The string is allocated using
1382 * xmalloc; it is the responsibility of the calling program to free it when
1383 * no longer needed. The length_ptr argument may be NULL, or point to an
1384 * integer into which the length of the string is stored.
1388 packet_get_string(u_int *length_ptr)
1390 return buffer_get_string(&incoming_packet, length_ptr);
1394 packet_get_string_ptr(u_int *length_ptr)
1396 return buffer_get_string_ptr(&incoming_packet, length_ptr);
1400 * Sends a diagnostic message from the server to the client. This message
1401 * can be sent at any time (but not while constructing another message). The
1402 * message is printed immediately, but only if the client is being executed
1403 * in verbose mode. These messages are primarily intended to ease debugging
1404 * authentication problems. The length of the formatted message must not
1405 * exceed 1024 bytes. This will automatically call packet_write_wait.
1409 packet_send_debug(const char *fmt,...)
1414 if (compat20 && (datafellows & SSH_BUG_DEBUG))
1417 va_start(args, fmt);
1418 vsnprintf(buf, sizeof(buf), fmt, args);
1422 packet_start(SSH2_MSG_DEBUG);
1423 packet_put_char(0); /* bool: always display */
1424 packet_put_cstring(buf);
1425 packet_put_cstring("");
1427 packet_start(SSH_MSG_DEBUG);
1428 packet_put_cstring(buf);
1431 packet_write_wait();
1435 * Logs the error plus constructs and sends a disconnect packet, closes the
1436 * connection, and exits. This function never returns. The error message
1437 * should not contain a newline. The length of the formatted message must
1438 * not exceed 1024 bytes.
1442 packet_disconnect(const char *fmt,...)
1446 static int disconnecting = 0;
1448 if (disconnecting) /* Guard against recursive invocations. */
1449 fatal("packet_disconnect called recursively.");
1453 * Format the message. Note that the caller must make sure the
1454 * message is of limited size.
1456 va_start(args, fmt);
1457 vsnprintf(buf, sizeof(buf), fmt, args);
1460 /* Display the error locally */
1461 logit("Disconnecting: %.100s", buf);
1463 /* Send the disconnect message to the other side, and wait for it to get sent. */
1465 packet_start(SSH2_MSG_DISCONNECT);
1466 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
1467 packet_put_cstring(buf);
1468 packet_put_cstring("");
1470 packet_start(SSH_MSG_DISCONNECT);
1471 packet_put_cstring(buf);
1474 packet_write_wait();
1476 /* Stop listening for connections. */
1477 channel_close_all();
1479 /* Close the connection. */
1484 /* Checks if there is any buffered output, and tries to write some of the output. */
1487 packet_write_poll(void)
1489 int len = buffer_len(&output);
1492 len = write(connection_out, buffer_ptr(&output), len);
1494 if (errno == EINTR || errno == EAGAIN ||
1495 errno == EWOULDBLOCK)
1497 fatal("Write failed: %.100s", strerror(errno));
1500 fatal("Write connection closed");
1501 buffer_consume(&output, len);
1507 * Calls packet_write_poll repeatedly until all pending output data has been
1512 packet_write_wait(void)
1516 struct timeval start, timeout, *timeoutp = NULL;
1518 setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS),
1520 packet_write_poll();
1521 while (packet_have_data_to_write()) {
1522 memset(setp, 0, howmany(connection_out + 1, NFDBITS) *
1524 FD_SET(connection_out, setp);
1526 if (packet_timeout_ms > 0) {
1527 ms_remain = packet_timeout_ms;
1528 timeoutp = &timeout;
1531 if (packet_timeout_ms != -1) {
1532 ms_to_timeval(&timeout, ms_remain);
1533 gettimeofday(&start, NULL);
1535 if ((ret = select(connection_out + 1, NULL, setp,
1536 NULL, timeoutp)) >= 0)
1538 if (errno != EAGAIN && errno != EINTR &&
1539 errno != EWOULDBLOCK)
1541 if (packet_timeout_ms == -1)
1543 ms_subtract_diff(&start, &ms_remain);
1544 if (ms_remain <= 0) {
1550 logit("Connection to %.200s timed out while "
1551 "waiting to write", get_remote_ipaddr());
1554 packet_write_poll();
1559 /* Returns true if there is buffered data to write to the connection. */
1562 packet_have_data_to_write(void)
1564 return buffer_len(&output) != 0;
1567 /* Returns true if there is not too much data to write to the connection. */
1570 packet_not_very_much_data_to_write(void)
1572 if (interactive_mode)
1573 return buffer_len(&output) < 16384;
1575 return buffer_len(&output) < 128 * 1024;
1580 packet_set_tos(int interactive)
1582 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1583 int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT;
1585 if (!packet_connection_is_on_socket() ||
1586 !packet_connection_is_ipv4())
1588 if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &tos,
1590 error("setsockopt IP_TOS %d: %.100s:",
1591 tos, strerror(errno));
1595 /* Informs that the current session is interactive. Sets IP flags for that. */
1598 packet_set_interactive(int interactive)
1600 static int called = 0;
1606 /* Record that we are in interactive mode. */
1607 interactive_mode = interactive;
1609 /* Only set socket options if using a socket. */
1610 if (!packet_connection_is_on_socket())
1612 set_nodelay(connection_in);
1613 packet_set_tos(interactive);
1616 /* Returns true if the current connection is interactive. */
1619 packet_is_interactive(void)
1621 return interactive_mode;
1625 packet_set_maxsize(u_int s)
1627 static int called = 0;
1630 logit("packet_set_maxsize: called twice: old %d new %d",
1631 max_packet_size, s);
1634 if (s < 4 * 1024 || s > 1024 * 1024) {
1635 logit("packet_set_maxsize: bad size %d", s);
1639 debug("packet_set_maxsize: setting to %d", s);
1640 max_packet_size = s;
1644 /* roundup current message to pad bytes */
1646 packet_add_padding(u_char pad)
1652 * 9.2. Ignored Data Message
1654 * byte SSH_MSG_IGNORE
1657 * All implementations MUST understand (and ignore) this message at any
1658 * time (after receiving the protocol version). No implementation is
1659 * required to send them. This message can be used as an additional
1660 * protection measure against advanced traffic analysis techniques.
1663 packet_send_ignore(int nbytes)
1668 packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
1669 packet_put_int(nbytes);
1670 for (i = 0; i < nbytes; i++) {
1673 packet_put_char((u_char)rnd & 0xff);
1678 #define MAX_PACKETS (1U<<31)
1680 packet_need_rekeying(void)
1682 if (datafellows & SSH_BUG_NOREKEY)
1685 (p_send.packets > MAX_PACKETS) ||
1686 (p_read.packets > MAX_PACKETS) ||
1687 (max_blocks_out && (p_send.blocks > max_blocks_out)) ||
1688 (max_blocks_in && (p_read.blocks > max_blocks_in));
1692 packet_set_rekey_limit(u_int32_t bytes)
1694 rekey_limit = bytes;
1698 packet_set_server(void)
1704 packet_set_authenticated(void)
1706 after_authentication = 1;