2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This file contains code implementing the packet protocol and communication
6 * with the other side. This same code is used both on client and server side.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
15 * SSH2 packet format added by Markus Friedl.
16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40 RCSID("$OpenBSD: packet.c,v 1.112 2003/09/23 20:17:11 markus Exp $");
42 #include "openbsd-compat/sys-queue.h"
74 * This variable contains the file descriptors used for communicating with
75 * the other side. connection_in is used for reading; connection_out for
76 * writing. These can be the same descriptor, in which case it is assumed to
79 static int connection_in
= -1;
80 static int connection_out
= -1;
82 /* Protocol flags for the remote side. */
83 static u_int remote_protocol_flags
= 0;
85 /* Encryption context for receiving data. This is only used for decryption. */
86 static CipherContext receive_context
;
88 /* Encryption context for sending data. This is only used for encryption. */
89 static CipherContext send_context
;
91 /* Buffer for raw input data from the socket. */
94 /* Buffer for raw output data going to the socket. */
97 /* Buffer for the partial outgoing packet being constructed. */
98 static Buffer outgoing_packet
;
100 /* Buffer for the incoming packet currently being processed. */
101 static Buffer incoming_packet
;
103 /* Scratch buffer for packet compression/decompression. */
104 static Buffer compression_buffer
;
105 static int compression_buffer_ready
= 0;
107 /* Flag indicating whether packet compression/decompression is enabled. */
108 static int packet_compression
= 0;
110 /* default maximum packet size */
111 u_int max_packet_size
= 32768;
113 /* Flag indicating whether this module has been initialized. */
114 static int initialized
= 0;
116 /* Set to true if the connection is interactive. */
117 static int interactive_mode
= 0;
119 /* Session key information for Encryption and MAC */
120 Newkeys
*newkeys
[MODE_MAX
];
121 static struct packet_state
{
127 static u_int64_t max_blocks_in
, max_blocks_out
;
128 static u_int32_t rekey_limit
;
130 /* Session key for protocol v1 */
131 static u_char ssh1_key
[SSH_SESSION_KEY_LENGTH
];
132 static u_int ssh1_keylen
;
134 /* roundup current message to extra_pad bytes */
135 static u_char extra_pad
= 0;
138 TAILQ_ENTRY(packet
) next
;
142 TAILQ_HEAD(, packet
) outgoing
;
145 * Sets the descriptors used for communication. Disables encryption until
146 * packet_set_encryption_key is called.
149 packet_set_connection(int fd_in
, int fd_out
)
151 Cipher
*none
= cipher_by_name("none");
154 fatal("packet_set_connection: cannot load cipher 'none'");
155 connection_in
= fd_in
;
156 connection_out
= fd_out
;
157 cipher_init(&send_context
, none
, "", 0, NULL
, 0, CIPHER_ENCRYPT
);
158 cipher_init(&receive_context
, none
, "", 0, NULL
, 0, CIPHER_DECRYPT
);
159 newkeys
[MODE_IN
] = newkeys
[MODE_OUT
] = NULL
;
163 buffer_init(&output
);
164 buffer_init(&outgoing_packet
);
165 buffer_init(&incoming_packet
);
166 TAILQ_INIT(&outgoing
);
170 /* Returns 1 if remote host is connected via socket, 0 if not. */
173 packet_connection_is_on_socket(void)
175 struct sockaddr_storage from
, to
;
176 socklen_t fromlen
, tolen
;
178 /* filedescriptors in and out are the same, so it's a socket */
179 if (connection_in
== connection_out
)
181 fromlen
= sizeof(from
);
182 memset(&from
, 0, sizeof(from
));
183 if (getpeername(connection_in
, (struct sockaddr
*)&from
, &fromlen
) < 0)
186 memset(&to
, 0, sizeof(to
));
187 if (getpeername(connection_out
, (struct sockaddr
*)&to
, &tolen
) < 0)
189 if (fromlen
!= tolen
|| memcmp(&from
, &to
, fromlen
) != 0)
191 if (from
.ss_family
!= AF_INET
&& from
.ss_family
!= AF_INET6
)
197 * Exports an IV from the CipherContext required to export the key
198 * state back from the unprivileged child to the privileged parent
203 packet_get_keyiv(int mode
, u_char
*iv
, u_int len
)
207 if (mode
== MODE_OUT
)
210 cc
= &receive_context
;
212 cipher_get_keyiv(cc
, iv
, len
);
216 packet_get_keycontext(int mode
, u_char
*dat
)
220 if (mode
== MODE_OUT
)
223 cc
= &receive_context
;
225 return (cipher_get_keycontext(cc
, dat
));
229 packet_set_keycontext(int mode
, u_char
*dat
)
233 if (mode
== MODE_OUT
)
236 cc
= &receive_context
;
238 cipher_set_keycontext(cc
, dat
);
242 packet_get_keyiv_len(int mode
)
246 if (mode
== MODE_OUT
)
249 cc
= &receive_context
;
251 return (cipher_get_keyiv_len(cc
));
254 packet_set_iv(int mode
, u_char
*dat
)
258 if (mode
== MODE_OUT
)
261 cc
= &receive_context
;
263 cipher_set_keyiv(cc
, dat
);
266 packet_get_ssh1_cipher(void)
268 return (cipher_get_number(receive_context
.cipher
));
272 packet_get_state(int mode
, u_int32_t
*seqnr
, u_int64_t
*blocks
, u_int32_t
*packets
)
274 struct packet_state
*state
;
276 state
= (mode
== MODE_IN
) ? &p_read
: &p_send
;
277 *seqnr
= state
->seqnr
;
278 *blocks
= state
->blocks
;
279 *packets
= state
->packets
;
283 packet_set_state(int mode
, u_int32_t seqnr
, u_int64_t blocks
, u_int32_t packets
)
285 struct packet_state
*state
;
287 state
= (mode
== MODE_IN
) ? &p_read
: &p_send
;
288 state
->seqnr
= seqnr
;
289 state
->blocks
= blocks
;
290 state
->packets
= packets
;
293 /* returns 1 if connection is via ipv4 */
296 packet_connection_is_ipv4(void)
298 struct sockaddr_storage to
;
299 socklen_t tolen
= sizeof(to
);
301 memset(&to
, 0, sizeof(to
));
302 if (getsockname(connection_out
, (struct sockaddr
*)&to
, &tolen
) < 0)
304 if (to
.ss_family
== AF_INET
)
307 if (to
.ss_family
== AF_INET6
&&
308 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6
*)&to
)->sin6_addr
))
314 /* Sets the connection into non-blocking mode. */
317 packet_set_nonblocking(void)
319 /* Set the socket into non-blocking mode. */
320 if (fcntl(connection_in
, F_SETFL
, O_NONBLOCK
) < 0)
321 error("fcntl O_NONBLOCK: %.100s", strerror(errno
));
323 if (connection_out
!= connection_in
) {
324 if (fcntl(connection_out
, F_SETFL
, O_NONBLOCK
) < 0)
325 error("fcntl O_NONBLOCK: %.100s", strerror(errno
));
329 /* Returns the socket used for reading. */
332 packet_get_connection_in(void)
334 return connection_in
;
337 /* Returns the descriptor used for writing. */
340 packet_get_connection_out(void)
342 return connection_out
;
345 /* Closes the connection and clears and frees internal data structures. */
353 if (connection_in
== connection_out
) {
354 shutdown(connection_out
, SHUT_RDWR
);
355 close(connection_out
);
357 close(connection_in
);
358 close(connection_out
);
361 buffer_free(&output
);
362 buffer_free(&outgoing_packet
);
363 buffer_free(&incoming_packet
);
364 if (compression_buffer_ready
) {
365 buffer_free(&compression_buffer
);
366 buffer_compress_uninit();
368 cipher_cleanup(&send_context
);
369 cipher_cleanup(&receive_context
);
372 /* Sets remote side protocol flags. */
375 packet_set_protocol_flags(u_int protocol_flags
)
377 remote_protocol_flags
= protocol_flags
;
380 /* Returns the remote protocol flags set earlier by the above function. */
383 packet_get_protocol_flags(void)
385 return remote_protocol_flags
;
389 * Starts packet compression from the next packet on in both directions.
390 * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
394 packet_init_compression(void)
396 if (compression_buffer_ready
== 1)
398 compression_buffer_ready
= 1;
399 buffer_init(&compression_buffer
);
403 packet_start_compression(int level
)
405 if (packet_compression
&& !compat20
)
406 fatal("Compression already enabled.");
407 packet_compression
= 1;
408 packet_init_compression();
409 buffer_compress_init_send(level
);
410 buffer_compress_init_recv();
414 * Causes any further packets to be encrypted using the given key. The same
415 * key is used for both sending and reception. However, both directions are
416 * encrypted independently of each other.
420 packet_set_encryption_key(const u_char
*key
, u_int keylen
,
423 Cipher
*cipher
= cipher_by_number(number
);
426 fatal("packet_set_encryption_key: unknown cipher number %d", number
);
428 fatal("packet_set_encryption_key: keylen too small: %d", keylen
);
429 if (keylen
> SSH_SESSION_KEY_LENGTH
)
430 fatal("packet_set_encryption_key: keylen too big: %d", keylen
);
431 memcpy(ssh1_key
, key
, keylen
);
432 ssh1_keylen
= keylen
;
433 cipher_init(&send_context
, cipher
, key
, keylen
, NULL
, 0, CIPHER_ENCRYPT
);
434 cipher_init(&receive_context
, cipher
, key
, keylen
, NULL
, 0, CIPHER_DECRYPT
);
438 packet_get_encryption_key(u_char
*key
)
441 return (ssh1_keylen
);
442 memcpy(key
, ssh1_key
, ssh1_keylen
);
443 return (ssh1_keylen
);
446 /* Start constructing a packet to send. */
448 packet_start(u_char type
)
453 DBG(debug("packet_start[%d]", type
));
454 len
= compat20
? 6 : 9;
455 memset(buf
, 0, len
- 1);
457 buffer_clear(&outgoing_packet
);
458 buffer_append(&outgoing_packet
, buf
, len
);
461 /* Append payload. */
463 packet_put_char(int value
)
467 buffer_append(&outgoing_packet
, &ch
, 1);
470 packet_put_int(u_int value
)
472 buffer_put_int(&outgoing_packet
, value
);
475 packet_put_string(const void *buf
, u_int len
)
477 buffer_put_string(&outgoing_packet
, buf
, len
);
480 packet_put_cstring(const char *str
)
482 buffer_put_cstring(&outgoing_packet
, str
);
485 packet_put_raw(const void *buf
, u_int len
)
487 buffer_append(&outgoing_packet
, buf
, len
);
490 packet_put_bignum(BIGNUM
* value
)
492 buffer_put_bignum(&outgoing_packet
, value
);
495 packet_put_bignum2(BIGNUM
* value
)
497 buffer_put_bignum2(&outgoing_packet
, value
);
501 * Finalizes and sends the packet. If the encryption key has been set,
502 * encrypts the packet before sending.
514 * If using packet compression, compress the payload of the outgoing
517 if (packet_compression
) {
518 buffer_clear(&compression_buffer
);
520 buffer_consume(&outgoing_packet
, 8);
522 buffer_append(&compression_buffer
, "\0\0\0\0\0\0\0\0", 8);
523 buffer_compress(&outgoing_packet
, &compression_buffer
);
524 buffer_clear(&outgoing_packet
);
525 buffer_append(&outgoing_packet
, buffer_ptr(&compression_buffer
),
526 buffer_len(&compression_buffer
));
528 /* Compute packet length without padding (add checksum, remove padding). */
529 len
= buffer_len(&outgoing_packet
) + 4 - 8;
531 /* Insert padding. Initialized to zero in packet_start1() */
532 padding
= 8 - len
% 8;
533 if (!send_context
.plaintext
) {
534 cp
= buffer_ptr(&outgoing_packet
);
535 for (i
= 0; i
< padding
; i
++) {
538 cp
[7 - i
] = rand
& 0xff;
542 buffer_consume(&outgoing_packet
, 8 - padding
);
544 /* Add check bytes. */
545 checksum
= ssh_crc32(buffer_ptr(&outgoing_packet
),
546 buffer_len(&outgoing_packet
));
547 PUT_32BIT(buf
, checksum
);
548 buffer_append(&outgoing_packet
, buf
, 4);
551 fprintf(stderr
, "packet_send plain: ");
552 buffer_dump(&outgoing_packet
);
555 /* Append to output. */
557 buffer_append(&output
, buf
, 4);
558 cp
= buffer_append_space(&output
, buffer_len(&outgoing_packet
));
559 cipher_crypt(&send_context
, cp
, buffer_ptr(&outgoing_packet
),
560 buffer_len(&outgoing_packet
));
563 fprintf(stderr
, "encrypted: ");
564 buffer_dump(&output
);
567 buffer_clear(&outgoing_packet
);
570 * Note that the packet is now only buffered in output. It won\'t be
571 * actually sent until packet_write_wait or packet_write_poll is
577 set_newkeys(int mode
)
583 u_int64_t
*max_blocks
;
586 debug2("set_newkeys: mode %d", mode
);
588 if (mode
== MODE_OUT
) {
590 encrypt
= CIPHER_ENCRYPT
;
591 p_send
.packets
= p_send
.blocks
= 0;
592 max_blocks
= &max_blocks_out
;
594 cc
= &receive_context
;
595 encrypt
= CIPHER_DECRYPT
;
596 p_read
.packets
= p_read
.blocks
= 0;
597 max_blocks
= &max_blocks_in
;
599 if (newkeys
[mode
] != NULL
) {
600 debug("set_newkeys: rekeying");
602 enc
= &newkeys
[mode
]->enc
;
603 mac
= &newkeys
[mode
]->mac
;
604 comp
= &newkeys
[mode
]->comp
;
605 memset(mac
->key
, 0, mac
->key_len
);
612 xfree(newkeys
[mode
]);
614 newkeys
[mode
] = kex_get_newkeys(mode
);
615 if (newkeys
[mode
] == NULL
)
616 fatal("newkeys: no keys for mode %d", mode
);
617 enc
= &newkeys
[mode
]->enc
;
618 mac
= &newkeys
[mode
]->mac
;
619 comp
= &newkeys
[mode
]->comp
;
622 DBG(debug("cipher_init_context: %d", mode
));
623 cipher_init(cc
, enc
->cipher
, enc
->key
, enc
->key_len
,
624 enc
->iv
, enc
->block_size
, encrypt
);
625 /* Deleting the keys does not gain extra security */
626 /* memset(enc->iv, 0, enc->block_size);
627 memset(enc->key, 0, enc->key_len); */
628 if (comp
->type
!= 0 && comp
->enabled
== 0) {
629 packet_init_compression();
630 if (mode
== MODE_OUT
)
631 buffer_compress_init_send(6);
633 buffer_compress_init_recv();
637 * The 2^(blocksize*2) limit is too expensive for 3DES,
638 * blowfish, etc, so enforce a 1GB limit for small blocksizes.
640 if (enc
->block_size
>= 16)
641 *max_blocks
= (u_int64_t
)1 << (enc
->block_size
*2);
643 *max_blocks
= ((u_int64_t
)1 << 30) / enc
->block_size
;
645 *max_blocks
= MIN(*max_blocks
, rekey_limit
/ enc
->block_size
);
649 * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
652 packet_send2_wrapped(void)
654 u_char type
, *cp
, *macbuf
= NULL
;
656 u_int packet_length
= 0;
664 if (newkeys
[MODE_OUT
] != NULL
) {
665 enc
= &newkeys
[MODE_OUT
]->enc
;
666 mac
= &newkeys
[MODE_OUT
]->mac
;
667 comp
= &newkeys
[MODE_OUT
]->comp
;
669 block_size
= enc
? enc
->block_size
: 8;
671 cp
= buffer_ptr(&outgoing_packet
);
675 fprintf(stderr
, "plain: ");
676 buffer_dump(&outgoing_packet
);
679 if (comp
&& comp
->enabled
) {
680 len
= buffer_len(&outgoing_packet
);
681 /* skip header, compress only payload */
682 buffer_consume(&outgoing_packet
, 5);
683 buffer_clear(&compression_buffer
);
684 buffer_compress(&outgoing_packet
, &compression_buffer
);
685 buffer_clear(&outgoing_packet
);
686 buffer_append(&outgoing_packet
, "\0\0\0\0\0", 5);
687 buffer_append(&outgoing_packet
, buffer_ptr(&compression_buffer
),
688 buffer_len(&compression_buffer
));
689 DBG(debug("compression: raw %d compressed %d", len
,
690 buffer_len(&outgoing_packet
)));
693 /* sizeof (packet_len + pad_len + payload) */
694 len
= buffer_len(&outgoing_packet
);
697 * calc size of padding, alloc space, get random data,
698 * minimum padding is 4 bytes
700 padlen
= block_size
- (len
% block_size
);
702 padlen
+= block_size
;
704 /* will wrap if extra_pad+padlen > 255 */
705 extra_pad
= roundup(extra_pad
, block_size
);
706 pad
= extra_pad
- ((len
+ padlen
) % extra_pad
);
707 debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)",
708 pad
, len
, padlen
, extra_pad
);
712 cp
= buffer_append_space(&outgoing_packet
, padlen
);
713 if (enc
&& !send_context
.plaintext
) {
715 for (i
= 0; i
< padlen
; i
++) {
723 memset(cp
, 0, padlen
);
725 /* packet_length includes payload, padding and padding length field */
726 packet_length
= buffer_len(&outgoing_packet
) - 4;
727 cp
= buffer_ptr(&outgoing_packet
);
728 PUT_32BIT(cp
, packet_length
);
730 DBG(debug("send: len %d (includes padlen %d)", packet_length
+4, padlen
));
732 /* compute MAC over seqnr and packet(length fields, payload, padding) */
733 if (mac
&& mac
->enabled
) {
734 macbuf
= mac_compute(mac
, p_send
.seqnr
,
735 buffer_ptr(&outgoing_packet
),
736 buffer_len(&outgoing_packet
));
737 DBG(debug("done calc MAC out #%d", p_send
.seqnr
));
739 /* encrypt packet and append to output buffer. */
740 cp
= buffer_append_space(&output
, buffer_len(&outgoing_packet
));
741 cipher_crypt(&send_context
, cp
, buffer_ptr(&outgoing_packet
),
742 buffer_len(&outgoing_packet
));
743 /* append unencrypted MAC */
744 if (mac
&& mac
->enabled
)
745 buffer_append(&output
, (char *)macbuf
, mac
->mac_len
);
747 fprintf(stderr
, "encrypted: ");
748 buffer_dump(&output
);
750 /* increment sequence number for outgoing packets */
751 if (++p_send
.seqnr
== 0)
752 logit("outgoing seqnr wraps around");
753 if (++p_send
.packets
== 0)
754 if (!(datafellows
& SSH_BUG_NOREKEY
))
755 fatal("XXX too many packets with same key");
756 p_send
.blocks
+= (packet_length
+ 4) / block_size
;
757 buffer_clear(&outgoing_packet
);
759 if (type
== SSH2_MSG_NEWKEYS
)
760 set_newkeys(MODE_OUT
);
766 static int rekeying
= 0;
770 cp
= buffer_ptr(&outgoing_packet
);
773 /* during rekeying we can only send key exchange messages */
775 if (!((type
>= SSH2_MSG_TRANSPORT_MIN
) &&
776 (type
<= SSH2_MSG_TRANSPORT_MAX
))) {
777 debug("enqueue packet: %u", type
);
778 p
= xmalloc(sizeof(*p
));
780 memcpy(&p
->payload
, &outgoing_packet
, sizeof(Buffer
));
781 buffer_init(&outgoing_packet
);
782 TAILQ_INSERT_TAIL(&outgoing
, p
, next
);
787 /* rekeying starts with sending KEXINIT */
788 if (type
== SSH2_MSG_KEXINIT
)
791 packet_send2_wrapped();
793 /* after a NEWKEYS message we can send the complete queue */
794 if (type
== SSH2_MSG_NEWKEYS
) {
796 while ((p
= TAILQ_FIRST(&outgoing
))) {
798 debug("dequeue packet: %u", type
);
799 buffer_free(&outgoing_packet
);
800 memcpy(&outgoing_packet
, &p
->payload
,
802 TAILQ_REMOVE(&outgoing
, p
, next
);
804 packet_send2_wrapped();
816 DBG(debug("packet_send done"));
820 * Waits until a packet has been received, and returns its type. Note that
821 * no other data is processed until this returns, so this function should not
822 * be used during the interactive session.
826 packet_read_seqnr(u_int32_t
*seqnr_p
)
831 DBG(debug("packet_read()"));
833 setp
= (fd_set
*)xmalloc(howmany(connection_in
+1, NFDBITS
) *
836 /* Since we are blocking, ensure that all written packets have been sent. */
839 /* Stay in the loop until we have received a complete packet. */
841 /* Try to read a packet from the buffer. */
842 type
= packet_read_poll_seqnr(seqnr_p
);
844 type
== SSH_SMSG_SUCCESS
845 || type
== SSH_SMSG_FAILURE
846 || type
== SSH_CMSG_EOF
847 || type
== SSH_CMSG_EXIT_CONFIRMATION
))
849 /* If we got a packet, return it. */
850 if (type
!= SSH_MSG_NONE
) {
855 * Otherwise, wait for some data to arrive, add it to the
856 * buffer, and try again.
858 memset(setp
, 0, howmany(connection_in
+ 1, NFDBITS
) *
860 FD_SET(connection_in
, setp
);
862 /* Wait for some data to arrive. */
863 while (select(connection_in
+ 1, setp
, NULL
, NULL
, NULL
) == -1 &&
864 (errno
== EAGAIN
|| errno
== EINTR
))
867 /* Read data from the socket. */
868 len
= read(connection_in
, buf
, sizeof(buf
));
870 logit("Connection closed by %.200s", get_remote_ipaddr());
874 fatal("Read from socket failed: %.100s", strerror(errno
));
875 /* Append it to the buffer. */
876 packet_process_incoming(buf
, len
);
884 return packet_read_seqnr(NULL
);
888 * Waits until a packet has been received, verifies that its type matches
889 * that given, and gives a fatal error and exits if there is a mismatch.
893 packet_read_expect(int expected_type
)
897 type
= packet_read();
898 if (type
!= expected_type
)
899 packet_disconnect("Protocol error: expected packet type %d, got %d",
900 expected_type
, type
);
903 /* Checks if a full packet is available in the data received so far via
904 * packet_process_incoming. If so, reads the packet; otherwise returns
905 * SSH_MSG_NONE. This does not wait for data from the connection.
907 * SSH_MSG_DISCONNECT is handled specially here. Also,
908 * SSH_MSG_IGNORE messages are skipped by this function and are never returned
913 packet_read_poll1(void)
915 u_int len
, padded_len
;
917 u_int checksum
, stored_checksum
;
919 /* Check if input size is less than minimum packet size. */
920 if (buffer_len(&input
) < 4 + 8)
922 /* Get length of incoming packet. */
923 cp
= buffer_ptr(&input
);
925 if (len
< 1 + 2 + 2 || len
> 256 * 1024)
926 packet_disconnect("Bad packet length %u.", len
);
927 padded_len
= (len
+ 8) & ~7;
929 /* Check if the packet has been entirely received. */
930 if (buffer_len(&input
) < 4 + padded_len
)
933 /* The entire packet is in buffer. */
935 /* Consume packet length. */
936 buffer_consume(&input
, 4);
939 * Cryptographic attack detector for ssh
940 * (C)1998 CORE-SDI, Buenos Aires Argentina
941 * Ariel Futoransky(futo@core-sdi.com)
943 if (!receive_context
.plaintext
&&
944 detect_attack(buffer_ptr(&input
), padded_len
, NULL
) == DEATTACK_DETECTED
)
945 packet_disconnect("crc32 compensation attack: network attack detected");
947 /* Decrypt data to incoming_packet. */
948 buffer_clear(&incoming_packet
);
949 cp
= buffer_append_space(&incoming_packet
, padded_len
);
950 cipher_crypt(&receive_context
, cp
, buffer_ptr(&input
), padded_len
);
952 buffer_consume(&input
, padded_len
);
955 fprintf(stderr
, "read_poll plain: ");
956 buffer_dump(&incoming_packet
);
959 /* Compute packet checksum. */
960 checksum
= ssh_crc32(buffer_ptr(&incoming_packet
),
961 buffer_len(&incoming_packet
) - 4);
964 buffer_consume(&incoming_packet
, 8 - len
% 8);
966 /* Test check bytes. */
967 if (len
!= buffer_len(&incoming_packet
))
968 packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
969 len
, buffer_len(&incoming_packet
));
971 cp
= (u_char
*)buffer_ptr(&incoming_packet
) + len
- 4;
972 stored_checksum
= GET_32BIT(cp
);
973 if (checksum
!= stored_checksum
)
974 packet_disconnect("Corrupted check bytes on input.");
975 buffer_consume_end(&incoming_packet
, 4);
977 if (packet_compression
) {
978 buffer_clear(&compression_buffer
);
979 buffer_uncompress(&incoming_packet
, &compression_buffer
);
980 buffer_clear(&incoming_packet
);
981 buffer_append(&incoming_packet
, buffer_ptr(&compression_buffer
),
982 buffer_len(&compression_buffer
));
984 type
= buffer_get_char(&incoming_packet
);
989 packet_read_poll2(u_int32_t
*seqnr_p
)
991 static u_int packet_length
= 0;
993 u_char
*macbuf
, *cp
, type
;
994 int maclen
, block_size
;
999 if (newkeys
[MODE_IN
] != NULL
) {
1000 enc
= &newkeys
[MODE_IN
]->enc
;
1001 mac
= &newkeys
[MODE_IN
]->mac
;
1002 comp
= &newkeys
[MODE_IN
]->comp
;
1004 maclen
= mac
&& mac
->enabled
? mac
->mac_len
: 0;
1005 block_size
= enc
? enc
->block_size
: 8;
1007 if (packet_length
== 0) {
1009 * check if input size is less than the cipher block size,
1010 * decrypt first block and extract length of incoming packet
1012 if (buffer_len(&input
) < block_size
)
1013 return SSH_MSG_NONE
;
1014 buffer_clear(&incoming_packet
);
1015 cp
= buffer_append_space(&incoming_packet
, block_size
);
1016 cipher_crypt(&receive_context
, cp
, buffer_ptr(&input
),
1018 cp
= buffer_ptr(&incoming_packet
);
1019 packet_length
= GET_32BIT(cp
);
1020 if (packet_length
< 1 + 4 || packet_length
> 256 * 1024) {
1022 buffer_dump(&incoming_packet
);
1024 packet_disconnect("Bad packet length %u.", packet_length
);
1026 DBG(debug("input: packet len %u", packet_length
+4));
1027 buffer_consume(&input
, block_size
);
1029 /* we have a partial packet of block_size bytes */
1030 need
= 4 + packet_length
- block_size
;
1031 DBG(debug("partial packet %d, need %d, maclen %d", block_size
,
1033 if (need
% block_size
!= 0)
1034 fatal("padding error: need %d block %d mod %d",
1035 need
, block_size
, need
% block_size
);
1037 * check if the entire packet has been received and
1038 * decrypt into incoming_packet
1040 if (buffer_len(&input
) < need
+ maclen
)
1041 return SSH_MSG_NONE
;
1043 fprintf(stderr
, "read_poll enc/full: ");
1044 buffer_dump(&input
);
1046 cp
= buffer_append_space(&incoming_packet
, need
);
1047 cipher_crypt(&receive_context
, cp
, buffer_ptr(&input
), need
);
1048 buffer_consume(&input
, need
);
1050 * compute MAC over seqnr and packet,
1051 * increment sequence number for incoming packet
1053 if (mac
&& mac
->enabled
) {
1054 macbuf
= mac_compute(mac
, p_read
.seqnr
,
1055 buffer_ptr(&incoming_packet
),
1056 buffer_len(&incoming_packet
));
1057 if (memcmp(macbuf
, buffer_ptr(&input
), mac
->mac_len
) != 0)
1058 packet_disconnect("Corrupted MAC on input.");
1059 DBG(debug("MAC #%d ok", p_read
.seqnr
));
1060 buffer_consume(&input
, mac
->mac_len
);
1062 if (seqnr_p
!= NULL
)
1063 *seqnr_p
= p_read
.seqnr
;
1064 if (++p_read
.seqnr
== 0)
1065 logit("incoming seqnr wraps around");
1066 if (++p_read
.packets
== 0)
1067 if (!(datafellows
& SSH_BUG_NOREKEY
))
1068 fatal("XXX too many packets with same key");
1069 p_read
.blocks
+= (packet_length
+ 4) / block_size
;
1072 cp
= buffer_ptr(&incoming_packet
);
1074 DBG(debug("input: padlen %d", padlen
));
1076 packet_disconnect("Corrupted padlen %d on input.", padlen
);
1078 /* skip packet size + padlen, discard padding */
1079 buffer_consume(&incoming_packet
, 4 + 1);
1080 buffer_consume_end(&incoming_packet
, padlen
);
1082 DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet
)));
1083 if (comp
&& comp
->enabled
) {
1084 buffer_clear(&compression_buffer
);
1085 buffer_uncompress(&incoming_packet
, &compression_buffer
);
1086 buffer_clear(&incoming_packet
);
1087 buffer_append(&incoming_packet
, buffer_ptr(&compression_buffer
),
1088 buffer_len(&compression_buffer
));
1089 DBG(debug("input: len after de-compress %d",
1090 buffer_len(&incoming_packet
)));
1093 * get packet type, implies consume.
1094 * return length of payload (without type field)
1096 type
= buffer_get_char(&incoming_packet
);
1097 if (type
== SSH2_MSG_NEWKEYS
)
1098 set_newkeys(MODE_IN
);
1100 fprintf(stderr
, "read/plain[%d]:\r\n", type
);
1101 buffer_dump(&incoming_packet
);
1103 /* reset for next packet */
1109 packet_read_poll_seqnr(u_int32_t
*seqnr_p
)
1111 u_int reason
, seqnr
;
1117 type
= packet_read_poll2(seqnr_p
);
1119 DBG(debug("received packet type %d", type
));
1121 case SSH2_MSG_IGNORE
:
1123 case SSH2_MSG_DEBUG
:
1125 msg
= packet_get_string(NULL
);
1126 debug("Remote: %.900s", msg
);
1128 msg
= packet_get_string(NULL
);
1131 case SSH2_MSG_DISCONNECT
:
1132 reason
= packet_get_int();
1133 msg
= packet_get_string(NULL
);
1134 logit("Received disconnect from %s: %u: %.400s",
1135 get_remote_ipaddr(), reason
, msg
);
1139 case SSH2_MSG_UNIMPLEMENTED
:
1140 seqnr
= packet_get_int();
1141 debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
1149 type
= packet_read_poll1();
1151 case SSH_MSG_IGNORE
:
1154 msg
= packet_get_string(NULL
);
1155 debug("Remote: %.900s", msg
);
1158 case SSH_MSG_DISCONNECT
:
1159 msg
= packet_get_string(NULL
);
1160 logit("Received disconnect from %s: %.400s",
1161 get_remote_ipaddr(), msg
);
1167 DBG(debug("received packet type %d", type
));
1176 packet_read_poll(void)
1178 return packet_read_poll_seqnr(NULL
);
1182 * Buffers the given amount of input characters. This is intended to be used
1183 * together with packet_read_poll.
1187 packet_process_incoming(const char *buf
, u_int len
)
1189 buffer_append(&input
, buf
, len
);
1192 /* Returns a character from the packet. */
1195 packet_get_char(void)
1199 buffer_get(&incoming_packet
, &ch
, 1);
1203 /* Returns an integer from the packet data. */
1206 packet_get_int(void)
1208 return buffer_get_int(&incoming_packet
);
1212 * Returns an arbitrary precision integer from the packet data. The integer
1213 * must have been initialized before this call.
1217 packet_get_bignum(BIGNUM
* value
)
1219 buffer_get_bignum(&incoming_packet
, value
);
1223 packet_get_bignum2(BIGNUM
* value
)
1225 buffer_get_bignum2(&incoming_packet
, value
);
1229 packet_get_raw(int *length_ptr
)
1231 int bytes
= buffer_len(&incoming_packet
);
1233 if (length_ptr
!= NULL
)
1234 *length_ptr
= bytes
;
1235 return buffer_ptr(&incoming_packet
);
1239 packet_remaining(void)
1241 return buffer_len(&incoming_packet
);
1245 * Returns a string from the packet data. The string is allocated using
1246 * xmalloc; it is the responsibility of the calling program to free it when
1247 * no longer needed. The length_ptr argument may be NULL, or point to an
1248 * integer into which the length of the string is stored.
1252 packet_get_string(u_int
*length_ptr
)
1254 return buffer_get_string(&incoming_packet
, length_ptr
);
1258 * Sends a diagnostic message from the server to the client. This message
1259 * can be sent at any time (but not while constructing another message). The
1260 * message is printed immediately, but only if the client is being executed
1261 * in verbose mode. These messages are primarily intended to ease debugging
1262 * authentication problems. The length of the formatted message must not
1263 * exceed 1024 bytes. This will automatically call packet_write_wait.
1267 packet_send_debug(const char *fmt
,...)
1272 if (compat20
&& (datafellows
& SSH_BUG_DEBUG
))
1275 va_start(args
, fmt
);
1276 vsnprintf(buf
, sizeof(buf
), fmt
, args
);
1280 packet_start(SSH2_MSG_DEBUG
);
1281 packet_put_char(0); /* bool: always display */
1282 packet_put_cstring(buf
);
1283 packet_put_cstring("");
1285 packet_start(SSH_MSG_DEBUG
);
1286 packet_put_cstring(buf
);
1289 packet_write_wait();
1293 * Logs the error plus constructs and sends a disconnect packet, closes the
1294 * connection, and exits. This function never returns. The error message
1295 * should not contain a newline. The length of the formatted message must
1296 * not exceed 1024 bytes.
1300 packet_disconnect(const char *fmt
,...)
1304 static int disconnecting
= 0;
1306 if (disconnecting
) /* Guard against recursive invocations. */
1307 fatal("packet_disconnect called recursively.");
1311 * Format the message. Note that the caller must make sure the
1312 * message is of limited size.
1314 va_start(args
, fmt
);
1315 vsnprintf(buf
, sizeof(buf
), fmt
, args
);
1318 /* Display the error locally */
1319 logit("Disconnecting: %.100s", buf
);
1321 /* Send the disconnect message to the other side, and wait for it to get sent. */
1323 packet_start(SSH2_MSG_DISCONNECT
);
1324 packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR
);
1325 packet_put_cstring(buf
);
1326 packet_put_cstring("");
1328 packet_start(SSH_MSG_DISCONNECT
);
1329 packet_put_cstring(buf
);
1332 packet_write_wait();
1334 /* Stop listening for connections. */
1335 channel_close_all();
1337 /* Close the connection. */
1342 /* Checks if there is any buffered output, and tries to write some of the output. */
1345 packet_write_poll(void)
1347 int len
= buffer_len(&output
);
1350 len
= write(connection_out
, buffer_ptr(&output
), len
);
1352 if (errno
== EAGAIN
)
1355 fatal("Write failed: %.100s", strerror(errno
));
1357 buffer_consume(&output
, len
);
1362 * Calls packet_write_poll repeatedly until all pending output data has been
1367 packet_write_wait(void)
1371 setp
= (fd_set
*)xmalloc(howmany(connection_out
+ 1, NFDBITS
) *
1373 packet_write_poll();
1374 while (packet_have_data_to_write()) {
1375 memset(setp
, 0, howmany(connection_out
+ 1, NFDBITS
) *
1377 FD_SET(connection_out
, setp
);
1378 while (select(connection_out
+ 1, NULL
, setp
, NULL
, NULL
) == -1 &&
1379 (errno
== EAGAIN
|| errno
== EINTR
))
1381 packet_write_poll();
1386 /* Returns true if there is buffered data to write to the connection. */
1389 packet_have_data_to_write(void)
1391 return buffer_len(&output
) != 0;
1394 /* Returns true if there is not too much data to write to the connection. */
1397 packet_not_very_much_data_to_write(void)
1399 if (interactive_mode
)
1400 return buffer_len(&output
) < 16384;
1402 return buffer_len(&output
) < 128 * 1024;
1407 packet_set_tos(int interactive
)
1409 #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN)
1410 int tos
= interactive
? IPTOS_LOWDELAY
: IPTOS_THROUGHPUT
;
1412 if (!packet_connection_is_on_socket() ||
1413 !packet_connection_is_ipv4())
1415 if (setsockopt(connection_in
, IPPROTO_IP
, IP_TOS
, &tos
,
1417 error("setsockopt IP_TOS %d: %.100s:",
1418 tos
, strerror(errno
));
1422 /* Informs that the current session is interactive. Sets IP flags for that. */
1425 packet_set_interactive(int interactive
)
1427 static int called
= 0;
1433 /* Record that we are in interactive mode. */
1434 interactive_mode
= interactive
;
1436 /* Only set socket options if using a socket. */
1437 if (!packet_connection_is_on_socket())
1440 set_nodelay(connection_in
);
1441 packet_set_tos(interactive
);
1444 /* Returns true if the current connection is interactive. */
1447 packet_is_interactive(void)
1449 return interactive_mode
;
1453 packet_set_maxsize(u_int s
)
1455 static int called
= 0;
1458 logit("packet_set_maxsize: called twice: old %d new %d",
1459 max_packet_size
, s
);
1462 if (s
< 4 * 1024 || s
> 1024 * 1024) {
1463 logit("packet_set_maxsize: bad size %d", s
);
1467 debug("packet_set_maxsize: setting to %d", s
);
1468 max_packet_size
= s
;
1472 /* roundup current message to pad bytes */
1474 packet_add_padding(u_char pad
)
1480 * 9.2. Ignored Data Message
1482 * byte SSH_MSG_IGNORE
1485 * All implementations MUST understand (and ignore) this message at any
1486 * time (after receiving the protocol version). No implementation is
1487 * required to send them. This message can be used as an additional
1488 * protection measure against advanced traffic analysis techniques.
1491 packet_send_ignore(int nbytes
)
1496 packet_start(compat20
? SSH2_MSG_IGNORE
: SSH_MSG_IGNORE
);
1497 packet_put_int(nbytes
);
1498 for (i
= 0; i
< nbytes
; i
++) {
1500 rand
= arc4random();
1501 packet_put_char(rand
& 0xff);
1506 #define MAX_PACKETS (1<<31)
1508 packet_need_rekeying(void)
1510 if (datafellows
& SSH_BUG_NOREKEY
)
1513 (p_send
.packets
> MAX_PACKETS
) ||
1514 (p_read
.packets
> MAX_PACKETS
) ||
1515 (max_blocks_out
&& (p_send
.blocks
> max_blocks_out
)) ||
1516 (max_blocks_in
&& (p_read
.blocks
> max_blocks_in
));
1520 packet_set_rekey_limit(u_int32_t bytes
)
1522 rekey_limit
= bytes
;