X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/388a146a2c587d56be04025c768708a606bec6a1..70e2f2f3229d9f1e106542302509e08567fc4cf8:/packet.c diff --git a/packet.c b/packet.c index a1e301d6..960675a9 100644 --- a/packet.c +++ b/packet.c @@ -1,31 +1,49 @@ /* - * - * packet.c - * * Author: Tatu Ylonen - * * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved - * - * Created: Sat Mar 18 02:40:40 1995 ylo - * * This file contains code implementing the packet protocol and communication * with the other side. This same code is used both on client and server side. * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". + * + * * SSH2 packet format added by Markus Friedl. + * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "includes.h" -RCSID("$Id$"); +RCSID("$OpenBSD: packet.c,v 1.85 2002/01/18 18:14:17 stevesk Exp $"); #include "xmalloc.h" #include "buffer.h" #include "packet.h" #include "bufaux.h" -#include "ssh.h" #include "crc32.h" -#include "cipher.h" #include "getput.h" #include "compress.h" @@ -33,22 +51,14 @@ RCSID("$Id$"); #include "channels.h" #include "compat.h" +#include "ssh1.h" #include "ssh2.h" -#ifdef HAVE_OPENSSL -# include -# include -# include -#endif /* HAVE_OPENSSL */ -#ifdef HAVE_SSL -# include -# include -# include -#endif /* HAVE_SSL */ - -#include "buffer.h" +#include "cipher.h" #include "kex.h" -#include "hmac.h" +#include "mac.h" +#include "log.h" +#include "canohost.h" #ifdef PACKET_DEBUG #define DBG(x) x @@ -65,14 +75,8 @@ RCSID("$Id$"); static int connection_in = -1; static int connection_out = -1; -/* - * Cipher type. This value is only used to determine whether to pad the - * packets with zeroes or random data. - */ -static int cipher_type = SSH_CIPHER_NONE; - /* Protocol flags for the remote side. */ -static unsigned int remote_protocol_flags = 0; +static u_int remote_protocol_flags = 0; /* Encryption context for receiving data. This is only used for decryption. */ static CipherContext receive_context; @@ -94,6 +98,7 @@ static Buffer incoming_packet; /* Scratch buffer for packet compression/decompression. */ static Buffer compression_buffer; +static int compression_buffer_ready = 0; /* Flag indicating whether packet compression/decompression is enabled. */ static int packet_compression = 0; @@ -107,40 +112,11 @@ static int initialized = 0; /* Set to true if the connection is interactive. */ static int interactive_mode = 0; -/* True if SSH2 packet format is used */ -int use_ssh2_packet_format = 0; - /* Session key information for Encryption and MAC */ -Kex *kex = NULL; +Newkeys *newkeys[MODE_MAX]; -void -packet_set_kex(Kex *k) -{ - if( k->mac[MODE_IN ].key == NULL || - k->enc[MODE_IN ].key == NULL || - k->enc[MODE_IN ].iv == NULL || - k->mac[MODE_OUT].key == NULL || - k->enc[MODE_OUT].key == NULL || - k->enc[MODE_OUT].iv == NULL) - fatal("bad KEX"); - kex = k; -} -void -clear_enc_keys(Enc *enc, int len) -{ - memset(enc->iv, 0, len); - memset(enc->key, 0, len); - xfree(enc->iv); - xfree(enc->key); - enc->iv = NULL; - enc->key = NULL; -} -void -packet_set_ssh2_format(void) -{ - debug("use_ssh2_packet_format"); - use_ssh2_packet_format = 1; -} +/* roundup current message to extra_pad bytes */ +static u_char extra_pad = 0; /* * Sets the descriptors used for communication. Disables encryption until @@ -149,11 +125,14 @@ packet_set_ssh2_format(void) void packet_set_connection(int fd_in, int fd_out) { + Cipher *none = cipher_by_name("none"); + if (none == NULL) + fatal("packet_set_connection: cannot load cipher 'none'"); connection_in = fd_in; connection_out = fd_out; - cipher_type = SSH_CIPHER_NONE; - cipher_set_key(&send_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 1); - cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *) "", 0, 0); + cipher_init(&send_context, none, "", 0, NULL, 0); + cipher_init(&receive_context, none, "", 0, NULL, 0); + newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; if (!initialized) { initialized = 1; buffer_init(&input); @@ -168,7 +147,7 @@ packet_set_connection(int fd_in, int fd_out) /* Returns 1 if remote host is connected via socket, 0 if not. */ int -packet_connection_is_on_socket() +packet_connection_is_on_socket(void) { struct sockaddr_storage from, to; socklen_t fromlen, tolen; @@ -194,7 +173,7 @@ packet_connection_is_on_socket() /* returns 1 if connection is via ipv4 */ int -packet_connection_is_ipv4() +packet_connection_is_ipv4(void) { struct sockaddr_storage to; socklen_t tolen = sizeof(to); @@ -210,7 +189,7 @@ packet_connection_is_ipv4() /* Sets the connection into non-blocking mode. */ void -packet_set_nonblocking() +packet_set_nonblocking(void) { /* Set the socket into non-blocking mode. */ if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) @@ -225,7 +204,7 @@ packet_set_nonblocking() /* Returns the socket used for reading. */ int -packet_get_connection_in() +packet_get_connection_in(void) { return connection_in; } @@ -233,7 +212,7 @@ packet_get_connection_in() /* Returns the descriptor used for writing. */ int -packet_get_connection_out() +packet_get_connection_out(void) { return connection_out; } @@ -241,7 +220,7 @@ packet_get_connection_out() /* Closes the connection and clears and frees internal data structures. */ void -packet_close() +packet_close(void) { if (!initialized) return; @@ -257,7 +236,7 @@ packet_close() buffer_free(&output); buffer_free(&outgoing_packet); buffer_free(&incoming_packet); - if (packet_compression) { + if (compression_buffer_ready) { buffer_free(&compression_buffer); buffer_compress_uninit(); } @@ -266,16 +245,15 @@ packet_close() /* Sets remote side protocol flags. */ void -packet_set_protocol_flags(unsigned int protocol_flags) +packet_set_protocol_flags(u_int protocol_flags) { remote_protocol_flags = protocol_flags; - channel_set_options((protocol_flags & SSH_PROTOFLAG_HOST_IN_FWD_OPEN) != 0); } /* Returns the remote protocol flags set earlier by the above function. */ -unsigned int -packet_get_protocol_flags() +u_int +packet_get_protocol_flags(void) { return remote_protocol_flags; } @@ -285,57 +263,24 @@ packet_get_protocol_flags() * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ -/*** XXXXX todo: kex means re-init */ -void -packet_start_compression(int level) +static void +packet_init_compression(void) { - if (packet_compression) - fatal("Compression already enabled."); - packet_compression = 1; + if (compression_buffer_ready == 1) + return; + compression_buffer_ready = 1; buffer_init(&compression_buffer); - buffer_compress_init(level); -} - -/* - * Encrypts the given number of bytes, copying from src to dest. bytes is - * known to be a multiple of 8. - */ - -void -packet_encrypt(CipherContext * cc, void *dest, void *src, - unsigned int bytes) -{ - cipher_encrypt(cc, dest, src, bytes); } -/* - * Decrypts the given number of bytes, copying from src to dest. bytes is - * known to be a multiple of 8. - */ - void -packet_decrypt(CipherContext * cc, void *dest, void *src, - unsigned int bytes) +packet_start_compression(int level) { - int i; - - if ((bytes % 8) != 0) - fatal("packet_decrypt: bad ciphertext length %d", bytes); - - /* - * Cryptographic attack detector for ssh - Modifications for packet.c - * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com) - */ - - if (cc->type == SSH_CIPHER_NONE || compat20) { - i = DEATTACK_OK; - } else { - i = detect_attack(src, bytes, NULL); - } - if (i == DEATTACK_DETECTED) - packet_disconnect("crc32 compensation attack: network attack detected"); - - cipher_decrypt(cc, dest, src, bytes); + if (packet_compression && !compat20) + fatal("Compression already enabled."); + packet_compression = 1; + packet_init_compression(); + buffer_compress_init_send(level); + buffer_compress_init_recv(); } /* @@ -343,94 +288,61 @@ packet_decrypt(CipherContext * cc, void *dest, void *src, * key is used for both sending and reception. However, both directions are * encrypted independently of each other. */ - void -packet_set_encryption_key(const unsigned char *key, unsigned int keylen, - int cipher) +packet_set_encryption_key(const u_char *key, u_int keylen, + int number) { + Cipher *cipher = cipher_by_number(number); + if (cipher == NULL) + fatal("packet_set_encryption_key: unknown cipher number %d", number); if (keylen < 20) - fatal("keylen too small: %d", keylen); - - /* All other ciphers use the same key in both directions for now. */ - cipher_set_key(&receive_context, cipher, key, keylen, 0); - cipher_set_key(&send_context, cipher, key, keylen, 1); -} - -/* Starts constructing a packet to send. */ - -void -packet_start1(int type) -{ - char buf[9]; - - buffer_clear(&outgoing_packet); - memset(buf, 0, 8); - buf[8] = type; - buffer_append(&outgoing_packet, buf, 9); + fatal("packet_set_encryption_key: keylen too small: %d", keylen); + cipher_init(&receive_context, cipher, key, keylen, NULL, 0); + cipher_init(&send_context, cipher, key, keylen, NULL, 0); } +/* Start constructing a packet to send. */ void -packet_start2(int type) +packet_start(u_char type) { - char buf[4+1+1]; + u_char buf[9]; + int len; + DBG(debug("packet_start[%d]", type)); + len = compat20 ? 6 : 9; + memset(buf, 0, len - 1); + buf[len - 1] = type; buffer_clear(&outgoing_packet); - memset(buf, 0, sizeof buf); - /* buf[0..3] = payload_len; */ - /* buf[4] = pad_len; */ - buf[5] = type & 0xff; - buffer_append(&outgoing_packet, buf, sizeof buf); -} - -void -packet_start(int type) -{ - DBG(debug("packet_start[%d]",type)); - if (use_ssh2_packet_format) - packet_start2(type); - else - packet_start1(type); + buffer_append(&outgoing_packet, buf, len); } -/* Appends a character to the packet data. */ - +/* Append payload. */ void packet_put_char(int value) { char ch = value; buffer_append(&outgoing_packet, &ch, 1); } - -/* Appends an integer to the packet data. */ - void -packet_put_int(unsigned int value) +packet_put_int(u_int value) { buffer_put_int(&outgoing_packet, value); } - -/* Appends a string to packet data. */ - void -packet_put_string(const char *buf, unsigned int len) +packet_put_string(const void *buf, u_int len) { buffer_put_string(&outgoing_packet, buf, len); } void packet_put_cstring(const char *str) { - buffer_put_string(&outgoing_packet, str, strlen(str)); + buffer_put_cstring(&outgoing_packet, str); } - void -packet_put_raw(const char *buf, unsigned int len) +packet_put_raw(const void *buf, u_int len) { buffer_append(&outgoing_packet, buf, len); } - - -/* Appends an arbitrary precision integer to packet data. */ - void packet_put_bignum(BIGNUM * value) { @@ -447,12 +359,12 @@ packet_put_bignum2(BIGNUM * value) * encrypts the packet before sending. */ -void -packet_send1() +static void +packet_send1(void) { char buf[8], *cp; int i, padding, len; - unsigned int checksum; + u_int checksum; u_int32_t rand = 0; /* @@ -468,14 +380,14 @@ packet_send1() buffer_compress(&outgoing_packet, &compression_buffer); buffer_clear(&outgoing_packet); buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), - buffer_len(&compression_buffer)); + buffer_len(&compression_buffer)); } /* Compute packet length without padding (add checksum, remove padding). */ len = buffer_len(&outgoing_packet) + 4 - 8; - /* Insert padding. */ + /* Insert padding. Initialized to zero in packet_start1() */ padding = 8 - len % 8; - if (cipher_type != SSH_CIPHER_NONE) { + if (send_context.cipher->number != SSH_CIPHER_NONE) { cp = buffer_ptr(&outgoing_packet); for (i = 0; i < padding; i++) { if (i % 4 == 0) @@ -487,8 +399,8 @@ packet_send1() buffer_consume(&outgoing_packet, 8 - padding); /* Add check bytes. */ - checksum = crc32((unsigned char *) buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet)); + checksum = ssh_crc32(buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); PUT_32BIT(buf, checksum); buffer_append(&outgoing_packet, buf, 4); @@ -500,9 +412,9 @@ packet_send1() /* Append to output. */ PUT_32BIT(buf, len); buffer_append(&output, buf, 4); - buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); - packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet)); + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); @@ -518,33 +430,83 @@ packet_send1() */ } +static void +set_newkeys(int mode) +{ + Enc *enc; + Mac *mac; + Comp *comp; + CipherContext *cc; + + debug("newkeys: mode %d", mode); + + cc = (mode == MODE_OUT) ? &send_context : &receive_context; + if (newkeys[mode] != NULL) { + debug("newkeys: rekeying"); + /* todo: free old keys, reset compression/cipher-ctxt; */ + memset(cc, 0, sizeof(*cc)); + enc = &newkeys[mode]->enc; + mac = &newkeys[mode]->mac; + comp = &newkeys[mode]->comp; + memset(mac->key, 0, mac->key_len); + xfree(enc->name); + xfree(enc->iv); + xfree(enc->key); + xfree(mac->name); + xfree(mac->key); + xfree(comp->name); + xfree(newkeys[mode]); + } + newkeys[mode] = kex_get_newkeys(mode); + if (newkeys[mode] == NULL) + fatal("newkeys: no keys for mode %d", mode); + enc = &newkeys[mode]->enc; + mac = &newkeys[mode]->mac; + comp = &newkeys[mode]->comp; + if (mac->md != NULL) + mac->enabled = 1; + DBG(debug("cipher_init_context: %d", mode)); + cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len, + enc->iv, enc->cipher->block_size); + memset(enc->iv, 0, enc->cipher->block_size); + memset(enc->key, 0, enc->cipher->key_len); + if (comp->type != 0 && comp->enabled == 0) { + packet_init_compression(); + if (mode == MODE_OUT) + buffer_compress_init_send(6); + else + buffer_compress_init_recv(); + comp->enabled = 1; + } +} + /* * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) */ -void -packet_send2() +static void +packet_send2(void) { - unsigned char *macbuf = NULL; + static u_int32_t seqnr = 0; + u_char type, *ucp, *macbuf = NULL; + u_char padlen, pad; char *cp; - unsigned int packet_length = 0; - unsigned int i, padlen, len; + u_int packet_length = 0; + u_int i, len; u_int32_t rand = 0; - static unsigned int seqnr = 0; - int type; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; int block_size; - if (kex != NULL) { - enc = &kex->enc[MODE_OUT]; - mac = &kex->mac[MODE_OUT]; - comp = &kex->comp[MODE_OUT]; + if (newkeys[MODE_OUT] != NULL) { + enc = &newkeys[MODE_OUT]->enc; + mac = &newkeys[MODE_OUT]->mac; + comp = &newkeys[MODE_OUT]->comp; } - block_size = enc ? enc->block_size : 8; + block_size = enc ? enc->cipher->block_size : 8; - cp = buffer_ptr(&outgoing_packet); - type = cp[5] & 0xff; + ucp = buffer_ptr(&outgoing_packet); + type = ucp[5]; #ifdef PACKET_DEBUG fprintf(stderr, "plain: "); @@ -575,34 +537,45 @@ packet_send2() padlen = block_size - (len % block_size); if (padlen < 4) padlen += block_size; - buffer_append_space(&outgoing_packet, &cp, padlen); - if (enc && enc->type != SSH_CIPHER_NONE) { + if (extra_pad) { + /* will wrap if extra_pad+padlen > 255 */ + extra_pad = roundup(extra_pad, block_size); + pad = extra_pad - ((len + padlen) % extra_pad); + debug("packet_send2: adding %d (len %d padlen %d extra_pad %d)", + pad, len, padlen, extra_pad); + padlen += pad; + extra_pad = 0; + } + cp = buffer_append_space(&outgoing_packet, padlen); + if (enc && enc->cipher->number != SSH_CIPHER_NONE) { + /* random padding */ for (i = 0; i < padlen; i++) { if (i % 4 == 0) rand = arc4random(); cp[i] = rand & 0xff; - rand <<= 8; + rand >>= 8; } + } else { + /* clear padding */ + memset(cp, 0, padlen); } /* packet_length includes payload, padding and padding length field */ packet_length = buffer_len(&outgoing_packet) - 4; - cp = buffer_ptr(&outgoing_packet); - PUT_32BIT(cp, packet_length); - cp[4] = padlen & 0xff; + ucp = buffer_ptr(&outgoing_packet); + PUT_32BIT(ucp, packet_length); + ucp[4] = padlen; DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); /* compute MAC over seqnr and packet(length fields, payload, padding) */ if (mac && mac->enabled) { - macbuf = hmac( mac->md, seqnr, - (unsigned char *) buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet), - mac->key, mac->key_len - ); - DBG(debug("done calc HMAC out #%d", seqnr)); + macbuf = mac_compute(mac, seqnr, + buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + DBG(debug("done calc MAC out #%d", seqnr)); } /* encrypt packet and append to output buffer. */ - buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); - packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), buffer_len(&outgoing_packet)); /* append unencrypted MAC */ if (mac && mac->enabled) @@ -611,46 +584,25 @@ packet_send2() fprintf(stderr, "encrypted: "); buffer_dump(&output); #endif - /* increment sequence number for outgoing packets */ - if (++seqnr == 0) - log("outgoing seqnr wraps around"); + /* increment sequence number for outgoing packets */ + if (++seqnr == 0) + log("outgoing seqnr wraps around"); buffer_clear(&outgoing_packet); - if (type == SSH2_MSG_NEWKEYS) { - if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) - fatal("packet_send2: no KEX"); - if (mac->md != NULL) - mac->enabled = 1; - debug("cipher_set_key_iv send_context"); - cipher_set_key_iv(&send_context, enc->type, - enc->key, enc->key_len, - enc->iv, enc->iv_len); - clear_enc_keys(enc, kex->we_need); - if (comp->type != 0 && comp->enabled == 0) { - comp->enabled = 1; - if (! packet_compression) - packet_start_compression(6); - } - } + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_OUT); } void -packet_send() +packet_send(void) { - if (use_ssh2_packet_format) + if (compat20) packet_send2(); else packet_send1(); DBG(debug("packet_send done")); } -void -packet_send_and_wait() -{ - packet_send(); - packet_write_wait(); -} - /* * Waits until a packet has been received, and returns its type. Note that * no other data is processed until this returns, so this function should not @@ -658,37 +610,46 @@ packet_send_and_wait() */ int -packet_read(int *payload_len_ptr) +packet_read_seqnr(u_int32_t *seqnr_p) { int type, len; - fd_set set; + fd_set *setp; char buf[8192]; DBG(debug("packet_read()")); + setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * + sizeof(fd_mask)); + /* Since we are blocking, ensure that all written packets have been sent. */ packet_write_wait(); /* Stay in the loop until we have received a complete packet. */ for (;;) { /* Try to read a packet from the buffer. */ - type = packet_read_poll(payload_len_ptr); - if (type == SSH_SMSG_SUCCESS + type = packet_read_poll_seqnr(seqnr_p); + if (!compat20 && ( + type == SSH_SMSG_SUCCESS || type == SSH_SMSG_FAILURE || type == SSH_CMSG_EOF - || type == SSH_CMSG_EXIT_CONFIRMATION) - packet_integrity_check(*payload_len_ptr, 0, type); + || type == SSH_CMSG_EXIT_CONFIRMATION)) + packet_check_eom(); /* If we got a packet, return it. */ - if (type != SSH_MSG_NONE) + if (type != SSH_MSG_NONE) { + xfree(setp); return type; + } /* * Otherwise, wait for some data to arrive, add it to the * buffer, and try again. */ - FD_ZERO(&set); - FD_SET(connection_in, &set); + memset(setp, 0, howmany(connection_in + 1, NFDBITS) * + sizeof(fd_mask)); + FD_SET(connection_in, setp); /* Wait for some data to arrive. */ - select(connection_in + 1, &set, NULL, NULL, NULL); + while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && + (errno == EAGAIN || errno == EINTR)) + ; /* Read data from the socket. */ len = read(connection_in, buf, sizeof(buf)); @@ -704,17 +665,23 @@ packet_read(int *payload_len_ptr) /* NOTREACHED */ } +int +packet_read(void) +{ + return packet_read_seqnr(NULL); +} + /* * Waits until a packet has been received, verifies that its type matches * that given, and gives a fatal error and exits if there is a mismatch. */ void -packet_read_expect(int *payload_len_ptr, int expected_type) +packet_read_expect(int expected_type) { int type; - type = packet_read(payload_len_ptr); + type = packet_read(); if (type != expected_type) packet_disconnect("Protocol error: expected packet type %d, got %d", expected_type, type); @@ -727,27 +694,21 @@ packet_read_expect(int *payload_len_ptr, int expected_type) * SSH_MSG_DISCONNECT is handled specially here. Also, * SSH_MSG_IGNORE messages are skipped by this function and are never returned * to higher levels. - * - * The returned payload_len does include space consumed by: - * Packet length - * Padding - * Packet type - * Check bytes */ -int -packet_read_poll1(int *payload_len_ptr) +static int +packet_read_poll1(void) { - unsigned int len, padded_len; - unsigned char *ucp; - char buf[8], *cp; - unsigned int checksum, stored_checksum; + u_int len, padded_len; + u_char *ucp, type; + char *cp; + u_int checksum, stored_checksum; /* Check if input size is less than minimum packet size. */ if (buffer_len(&input) < 4 + 8) return SSH_MSG_NONE; /* Get length of incoming packet. */ - ucp = (unsigned char *) buffer_ptr(&input); + ucp = buffer_ptr(&input); len = GET_32BIT(ucp); if (len < 1 + 2 + 2 || len > 256 * 1024) packet_disconnect("Bad packet length %d.", len); @@ -762,10 +723,20 @@ packet_read_poll1(int *payload_len_ptr) /* Consume packet length. */ buffer_consume(&input, 4); - /* Copy data to incoming_packet. */ + /* + * Cryptographic attack detector for ssh + * (C)1998 CORE-SDI, Buenos Aires Argentina + * Ariel Futoransky(futo@core-sdi.com) + */ + if (receive_context.cipher->number != SSH_CIPHER_NONE && + detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) + packet_disconnect("crc32 compensation attack: network attack detected"); + + /* Decrypt data to incoming_packet. */ buffer_clear(&incoming_packet); - buffer_append_space(&incoming_packet, &cp, padded_len); - packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); + cp = buffer_append_space(&incoming_packet, padded_len); + cipher_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); + buffer_consume(&input, padded_len); #ifdef PACKET_DEBUG @@ -774,25 +745,23 @@ packet_read_poll1(int *payload_len_ptr) #endif /* Compute packet checksum. */ - checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet), + checksum = ssh_crc32(buffer_ptr(&incoming_packet), buffer_len(&incoming_packet) - 4); /* Skip padding. */ buffer_consume(&incoming_packet, 8 - len % 8); /* Test check bytes. */ - if (len != buffer_len(&incoming_packet)) - packet_disconnect("packet_read_poll: len %d != buffer_len %d.", + packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", len, buffer_len(&incoming_packet)); - ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4; + ucp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; stored_checksum = GET_32BIT(ucp); if (checksum != stored_checksum) packet_disconnect("Corrupted check bytes on input."); buffer_consume_end(&incoming_packet, 4); - /* If using packet compression, decompress the packet. */ if (packet_compression) { buffer_clear(&compression_buffer); buffer_uncompress(&incoming_packet, &compression_buffer); @@ -800,38 +769,30 @@ packet_read_poll1(int *payload_len_ptr) buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), buffer_len(&compression_buffer)); } - /* Get packet type. */ - buffer_get(&incoming_packet, &buf[0], 1); - - /* Return length of payload (without type field). */ - *payload_len_ptr = buffer_len(&incoming_packet); - - /* Return type. */ - return (unsigned char) buf[0]; + type = buffer_get_char(&incoming_packet); + return type; } -int -packet_read_poll2(int *payload_len_ptr) +static int +packet_read_poll2(u_int32_t *seqnr_p) { - unsigned int padlen, need; - unsigned char buf[8], *macbuf; - unsigned char *ucp; + static u_int32_t seqnr = 0; + static u_int packet_length = 0; + u_int padlen, need; + u_char *macbuf, *ucp, type; char *cp; - static unsigned int packet_length = 0; - static unsigned int seqnr = 0; - int type; int maclen, block_size; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; - if (kex != NULL) { - enc = &kex->enc[MODE_IN]; - mac = &kex->mac[MODE_IN]; - comp = &kex->comp[MODE_IN]; + if (newkeys[MODE_IN] != NULL) { + enc = &newkeys[MODE_IN]->enc; + mac = &newkeys[MODE_IN]->mac; + comp = &newkeys[MODE_IN]->comp; } maclen = mac && mac->enabled ? mac->mac_len : 0; - block_size = enc ? enc->block_size : 8; + block_size = enc ? enc->cipher->block_size : 8; if (packet_length == 0) { /* @@ -841,10 +802,10 @@ packet_read_poll2(int *payload_len_ptr) if (buffer_len(&input) < block_size) return SSH_MSG_NONE; buffer_clear(&incoming_packet); - buffer_append_space(&incoming_packet, &cp, block_size); - packet_decrypt(&receive_context, cp, buffer_ptr(&input), + cp = buffer_append_space(&incoming_packet, block_size); + cipher_decrypt(&receive_context, cp, buffer_ptr(&input), block_size); - ucp = (unsigned char *) buffer_ptr(&incoming_packet); + ucp = buffer_ptr(&incoming_packet); packet_length = GET_32BIT(ucp); if (packet_length < 1 + 4 || packet_length > 256 * 1024) { buffer_dump(&incoming_packet); @@ -870,30 +831,31 @@ packet_read_poll2(int *payload_len_ptr) fprintf(stderr, "read_poll enc/full: "); buffer_dump(&input); #endif - buffer_append_space(&incoming_packet, &cp, need); - packet_decrypt(&receive_context, cp, buffer_ptr(&input), need); + cp = buffer_append_space(&incoming_packet, need); + cipher_decrypt(&receive_context, cp, buffer_ptr(&input), need); buffer_consume(&input, need); /* * compute MAC over seqnr and packet, * increment sequence number for incoming packet */ - if (mac && mac->enabled) { - macbuf = hmac( mac->md, seqnr, - (unsigned char *) buffer_ptr(&incoming_packet), - buffer_len(&incoming_packet), - mac->key, mac->key_len - ); + if (mac && mac->enabled) { + macbuf = mac_compute(mac, seqnr, + buffer_ptr(&incoming_packet), + buffer_len(&incoming_packet)); if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) - packet_disconnect("Corrupted HMAC on input."); - DBG(debug("HMAC #%d ok", seqnr)); + packet_disconnect("Corrupted MAC on input."); + DBG(debug("MAC #%d ok", seqnr)); buffer_consume(&input, mac->mac_len); } - if (++seqnr == 0) - log("incoming seqnr wraps around"); + if (seqnr_p != NULL) + *seqnr_p = seqnr; + if (++seqnr == 0) + log("incoming seqnr wraps around"); /* get padlen */ - cp = buffer_ptr(&incoming_packet) + 4; - padlen = *cp & 0xff; + cp = buffer_ptr(&incoming_packet); + cp += 4; + padlen = (u_char) *cp; DBG(debug("input: padlen %d", padlen)); if (padlen < 4) packet_disconnect("Corrupted padlen %d on input.", padlen); @@ -915,53 +877,31 @@ packet_read_poll2(int *payload_len_ptr) * get packet type, implies consume. * return length of payload (without type field) */ - buffer_get(&incoming_packet, (char *)&buf[0], 1); - *payload_len_ptr = buffer_len(&incoming_packet); - - /* reset for next packet */ - packet_length = 0; - - /* extract packet type */ - type = (unsigned char)buf[0]; - - if (type == SSH2_MSG_NEWKEYS) { - if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) - fatal("packet_read_poll2: no KEX"); - if (mac->md != NULL) - mac->enabled = 1; - debug("cipher_set_key_iv receive_context"); - cipher_set_key_iv(&receive_context, enc->type, - enc->key, enc->key_len, - enc->iv, enc->iv_len); - clear_enc_keys(enc, kex->we_need); - if (comp->type != 0 && comp->enabled == 0) { - comp->enabled = 1; - if (! packet_compression) - packet_start_compression(6); - } - } - + type = buffer_get_char(&incoming_packet); + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_IN); #ifdef PACKET_DEBUG - fprintf(stderr, "read/plain[%d]:\r\n",type); + fprintf(stderr, "read/plain[%d]:\r\n", type); buffer_dump(&incoming_packet); #endif - return (unsigned char)type; + /* reset for next packet */ + packet_length = 0; + return type; } int -packet_read_poll(int *payload_len_ptr) +packet_read_poll_seqnr(u_int32_t *seqnr_p) { + int reason, seqnr; + u_char type; char *msg; - for (;;) { - int type = use_ssh2_packet_format ? - packet_read_poll2(payload_len_ptr): - packet_read_poll1(payload_len_ptr); - if(compat20) { - int reason; - if (type != 0) + for (;;) { + if (compat20) { + type = packet_read_poll2(seqnr_p); + if (type) DBG(debug("received packet type %d", type)); - switch(type) { + switch (type) { case SSH2_MSG_IGNORE: break; case SSH2_MSG_DEBUG: @@ -975,16 +915,22 @@ packet_read_poll(int *payload_len_ptr) case SSH2_MSG_DISCONNECT: reason = packet_get_int(); msg = packet_get_string(NULL); - log("Received disconnect: %d: %.900s", reason, msg); + log("Received disconnect from %s: %d: %.400s", get_remote_ipaddr(), + reason, msg); xfree(msg); fatal_cleanup(); break; + case SSH2_MSG_UNIMPLEMENTED: + seqnr = packet_get_int(); + debug("Received SSH2_MSG_UNIMPLEMENTED for %d", seqnr); + break; default: return type; break; - } + } } else { - switch(type) { + type = packet_read_poll1(); + switch (type) { case SSH_MSG_IGNORE: break; case SSH_MSG_DEBUG: @@ -994,45 +940,52 @@ packet_read_poll(int *payload_len_ptr) break; case SSH_MSG_DISCONNECT: msg = packet_get_string(NULL); - log("Received disconnect: %.900s", msg); + log("Received disconnect from %s: %.400s", get_remote_ipaddr(), + msg); fatal_cleanup(); xfree(msg); break; default: - if (type != 0) + if (type) DBG(debug("received packet type %d", type)); return type; break; - } + } } } } +int +packet_read_poll(void) +{ + return packet_read_poll_seqnr(NULL); +} + /* * Buffers the given amount of input characters. This is intended to be used * together with packet_read_poll. */ void -packet_process_incoming(const char *buf, unsigned int len) +packet_process_incoming(const char *buf, u_int len) { buffer_append(&input, buf, len); } /* Returns a character from the packet. */ -unsigned int -packet_get_char() +u_int +packet_get_char(void) { char ch; buffer_get(&incoming_packet, &ch, 1); - return (unsigned char) ch; + return (u_char) ch; } /* Returns an integer from the packet data. */ -unsigned int -packet_get_int() +u_int +packet_get_int(void) { return buffer_get_int(&incoming_packet); } @@ -1043,18 +996,18 @@ packet_get_int() */ void -packet_get_bignum(BIGNUM * value, int *length_ptr) +packet_get_bignum(BIGNUM * value) { - *length_ptr = buffer_get_bignum(&incoming_packet, value); + buffer_get_bignum(&incoming_packet, value); } void -packet_get_bignum2(BIGNUM * value, int *length_ptr) +packet_get_bignum2(BIGNUM * value) { - *length_ptr = buffer_get_bignum2(&incoming_packet, value); + buffer_get_bignum2(&incoming_packet, value); } -char * +void * packet_get_raw(int *length_ptr) { int bytes = buffer_len(&incoming_packet); @@ -1063,6 +1016,12 @@ packet_get_raw(int *length_ptr) return buffer_ptr(&incoming_packet); } +int +packet_remaining(void) +{ + return buffer_len(&incoming_packet); +} + /* * Returns a string from the packet data. The string is allocated using * xmalloc; it is the responsibility of the calling program to free it when @@ -1070,8 +1029,8 @@ packet_get_raw(int *length_ptr) * integer into which the length of the string is stored. */ -char * -packet_get_string(unsigned int *length_ptr) +void * +packet_get_string(u_int *length_ptr) { return buffer_get_string(&incoming_packet, length_ptr); } @@ -1091,12 +1050,22 @@ packet_send_debug(const char *fmt,...) char buf[1024]; va_list args; + if (compat20 && (datafellows & SSH_BUG_DEBUG)) + return; + va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); - packet_start(SSH_MSG_DEBUG); - packet_put_string(buf, strlen(buf)); + if (compat20) { + packet_start(SSH2_MSG_DEBUG); + packet_put_char(0); /* bool: always display */ + packet_put_cstring(buf); + packet_put_cstring(""); + } else { + packet_start(SSH_MSG_DEBUG); + packet_put_cstring(buf); + } packet_send(); packet_write_wait(); } @@ -1134,13 +1103,13 @@ packet_disconnect(const char *fmt,...) packet_put_cstring(""); } else { packet_start(SSH_MSG_DISCONNECT); - packet_put_string(buf, strlen(buf)); + packet_put_cstring(buf); } packet_send(); packet_write_wait(); /* Stop listening for connections. */ - channel_stop_listening(); + channel_close_all(); /* Close the connection. */ packet_close(); @@ -1153,7 +1122,7 @@ packet_disconnect(const char *fmt,...) /* Checks if there is any buffered output, and tries to write some of the output. */ void -packet_write_poll() +packet_write_poll(void) { int len = buffer_len(&output); if (len > 0) { @@ -1174,22 +1143,29 @@ packet_write_poll() */ void -packet_write_wait() +packet_write_wait(void) { + fd_set *setp; + + setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * + sizeof(fd_mask)); packet_write_poll(); while (packet_have_data_to_write()) { - fd_set set; - FD_ZERO(&set); - FD_SET(connection_out, &set); - select(connection_out + 1, NULL, &set, NULL, NULL); + memset(setp, 0, howmany(connection_out + 1, NFDBITS) * + sizeof(fd_mask)); + FD_SET(connection_out, setp); + while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && + (errno == EAGAIN || errno == EINTR)) + ; packet_write_poll(); } + xfree(setp); } /* Returns true if there is buffered data to write to the connection. */ int -packet_have_data_to_write() +packet_have_data_to_write(void) { return buffer_len(&output) != 0; } @@ -1197,7 +1173,7 @@ packet_have_data_to_write() /* Returns true if there is not too much data to write to the connection. */ int -packet_not_very_much_data_to_write() +packet_not_very_much_data_to_write(void) { if (interactive_mode) return buffer_len(&output) < 16384; @@ -1208,55 +1184,61 @@ packet_not_very_much_data_to_write() /* Informs that the current session is interactive. Sets IP flags for that. */ void -packet_set_interactive(int interactive, int keepalives) +packet_set_interactive(int interactive) { + static int called = 0; +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + int lowdelay = IPTOS_LOWDELAY; + int throughput = IPTOS_THROUGHPUT; +#endif int on = 1; + if (called) + return; + called = 1; + /* Record that we are in interactive mode. */ interactive_mode = interactive; /* Only set socket options if using a socket. */ if (!packet_connection_is_on_socket()) return; - if (keepalives) { - /* Set keepalives if requested. */ - if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on, - sizeof(on)) < 0) - error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); - } /* - * IPTOS_LOWDELAY, TCP_NODELAY and IPTOS_THROUGHPUT are IPv4 only + * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only */ - if (!packet_connection_is_ipv4()) - return; if (interactive) { /* * Set IP options for an interactive connection. Use * IPTOS_LOWDELAY and TCP_NODELAY. */ - int lowdelay = IPTOS_LOWDELAY; - if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay, - sizeof(lowdelay)) < 0) - error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno)); +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + if (packet_connection_is_ipv4()) { + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, + (void *) &lowdelay, sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", + strerror(errno)); + } +#endif if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, sizeof(on)) < 0) error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); - } else { + } else if (packet_connection_is_ipv4()) { /* * Set IP options for a non-interactive connection. Use * IPTOS_THROUGHPUT. */ - int throughput = IPTOS_THROUGHPUT; +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, sizeof(throughput)) < 0) error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); +#endif } } /* Returns true if the current connection is interactive. */ int -packet_is_interactive() +packet_is_interactive(void) { return interactive_mode; } @@ -1274,7 +1256,42 @@ packet_set_maxsize(int s) log("packet_set_maxsize: bad size %d", s); return -1; } - log("packet_set_maxsize: setting to %d", s); + called = 1; + debug("packet_set_maxsize: setting to %d", s); max_packet_size = s; return s; } + +/* roundup current message to pad bytes */ +void +packet_add_padding(u_char pad) +{ + extra_pad = pad; +} + +/* + * 9.2. Ignored Data Message + * + * byte SSH_MSG_IGNORE + * string data + * + * All implementations MUST understand (and ignore) this message at any + * time (after receiving the protocol version). No implementation is + * required to send them. This message can be used as an additional + * protection measure against advanced traffic analysis techniques. + */ +void +packet_send_ignore(int nbytes) +{ + u_int32_t rand = 0; + int i; + + packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); + packet_put_int(nbytes); + for (i = 0; i < nbytes; i++) { + if (i % 4 == 0) + rand = arc4random(); + packet_put_char(rand & 0xff); + rand >>= 8; + } +}