=================================================================== RCS file: /cvsrepo/anoncvs/cvs/src/usr.bin/ssh/packet.c,v retrieving revision 1.32 retrieving revision 1.32.2.4 diff -u -r1.32 -r1.32.2.4 --- src/usr.bin/ssh/packet.c 2000/05/04 22:22:43 1.32 +++ src/usr.bin/ssh/packet.c 2001/03/21 18:52:55 1.32.2.4 @@ -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 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: packet.c,v 1.32 2000/05/04 22:22:43 markus Exp $"); +RCSID("$OpenBSD: packet.c,v 1.32.2.4 2001/03/21 18:52:55 jason 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" @@ -33,14 +51,14 @@ #include "channels.h" #include "compat.h" +#include "ssh1.h" #include "ssh2.h" -#include -#include -#include -#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 @@ -64,7 +82,7 @@ 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; @@ -141,11 +159,14 @@ 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); - cipher_set_key(&receive_context, SSH_CIPHER_NONE, (unsigned char *) "", 0); + cipher_init(&send_context, none, (u_char *) "", 0, NULL, 0); + cipher_init(&receive_context, none, (u_char *) "", 0, NULL, 0); if (!initialized) { initialized = 1; buffer_init(&input); @@ -258,7 +279,7 @@ /* 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); @@ -266,7 +287,7 @@ /* Returns the remote protocol flags set earlier by the above function. */ -unsigned int +u_int packet_get_protocol_flags() { return remote_protocol_flags; @@ -295,7 +316,7 @@ void packet_encrypt(CipherContext * cc, void *dest, void *src, - unsigned int bytes) + u_int bytes) { cipher_encrypt(cc, dest, src, bytes); } @@ -306,28 +327,18 @@ */ void -packet_decrypt(CipherContext * cc, void *dest, void *src, - unsigned int bytes) +packet_decrypt(CipherContext *context, void *dest, void *src, u_int bytes) { - 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) + if (!compat20 && + context->cipher->number != SSH_CIPHER_NONE && + detect_attack(src, bytes, NULL) == DEATTACK_DETECTED) packet_disconnect("crc32 compensation attack: network attack detected"); - cipher_decrypt(cc, dest, src, bytes); + cipher_decrypt(context, dest, src, bytes); } /* @@ -337,15 +348,16 @@ */ 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); - cipher_set_key(&send_context, cipher, key, keylen); + 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); } /* Starts constructing a packet to send. */ @@ -377,7 +389,7 @@ void packet_start(int type) { - DBG(debug("packet_start[%d]",type)); + DBG(debug("packet_start[%d]", type)); if (use_ssh2_packet_format) packet_start2(type); else @@ -396,7 +408,7 @@ /* 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); } @@ -404,7 +416,7 @@ /* Appends a string to packet data. */ void -packet_put_string(const char *buf, unsigned int len) +packet_put_string(const char *buf, u_int len) { buffer_put_string(&outgoing_packet, buf, len); } @@ -415,7 +427,7 @@ } void -packet_put_raw(const char *buf, unsigned int len) +packet_put_raw(const char *buf, u_int len) { buffer_append(&outgoing_packet, buf, len); } @@ -440,11 +452,11 @@ */ void -packet_send1() +packet_send1(void) { char buf[8], *cp; int i, padding, len; - unsigned int checksum; + u_int checksum; u_int32_t rand = 0; /* @@ -479,8 +491,8 @@ buffer_consume(&outgoing_packet, 8 - padding); /* Add check bytes. */ - checksum = crc32((unsigned char *) buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet)); + checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); PUT_32BIT(buf, checksum); buffer_append(&outgoing_packet, buf, 4); @@ -514,14 +526,14 @@ * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) */ void -packet_send2() +packet_send2(void) { - unsigned char *macbuf = NULL; + static u_int32_t seqnr = 0; + u_char *macbuf = NULL; char *cp; - unsigned int packet_length = 0; - unsigned int i, padlen, len; + u_int packet_length = 0; + u_int i, padlen, len; u_int32_t rand = 0; - static unsigned int seqnr = 0; int type; Enc *enc = NULL; Mac *mac = NULL; @@ -533,7 +545,7 @@ mac = &kex->mac[MODE_OUT]; comp = &kex->comp[MODE_OUT]; } - block_size = enc ? enc->block_size : 8; + block_size = enc ? enc->cipher->block_size : 8; cp = buffer_ptr(&outgoing_packet); type = cp[5] & 0xff; @@ -568,13 +580,13 @@ if (padlen < 4) padlen += block_size; buffer_append_space(&outgoing_packet, &cp, padlen); - if (enc && enc->type != SSH_CIPHER_NONE) { + 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 */ @@ -589,12 +601,10 @@ /* 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, + (u_char *) 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)); @@ -617,10 +627,10 @@ fatal("packet_send2: no KEX"); if (mac->md != NULL) mac->enabled = 1; - DBG(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); + DBG(debug("cipher_init send_context")); + cipher_init(&send_context, enc->cipher, + enc->key, enc->cipher->key_len, + enc->iv, enc->cipher->block_size); clear_enc_keys(enc, kex->we_need); if (comp->type != 0 && comp->enabled == 0) { comp->enabled = 1; @@ -650,10 +660,13 @@ packet_read(int *payload_len_ptr) { 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(); @@ -668,17 +681,22 @@ || type == SSH_CMSG_EXIT_CONFIRMATION)) packet_integrity_check(*payload_len_ptr, 0, type); /* 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)); @@ -728,16 +746,16 @@ int packet_read_poll1(int *payload_len_ptr) { - unsigned int len, padded_len; - unsigned char *ucp; + u_int len, padded_len; + u_char *ucp; char buf[8], *cp; - unsigned int checksum, stored_checksum; + 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 = (u_char *) buffer_ptr(&input); len = GET_32BIT(ucp); if (len < 1 + 2 + 2 || len > 256 * 1024) packet_disconnect("Bad packet length %d.", len); @@ -764,7 +782,7 @@ #endif /* Compute packet checksum. */ - checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet), + checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet), buffer_len(&incoming_packet) - 4); /* Skip padding. */ @@ -776,7 +794,7 @@ packet_disconnect("packet_read_poll: 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."); @@ -797,18 +815,18 @@ *payload_len_ptr = buffer_len(&incoming_packet); /* Return type. */ - return (unsigned char) buf[0]; + return (u_char) buf[0]; } int packet_read_poll2(int *payload_len_ptr) { - 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 buf[8], *macbuf; + u_char *ucp; char *cp; - static unsigned int packet_length = 0; - static unsigned int seqnr = 0; int type; int maclen, block_size; Enc *enc = NULL; @@ -821,7 +839,7 @@ comp = &kex->comp[MODE_IN]; } 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) { /* @@ -834,7 +852,7 @@ buffer_append_space(&incoming_packet, &cp, block_size); packet_decrypt(&receive_context, cp, buffer_ptr(&input), block_size); - ucp = (unsigned char *) buffer_ptr(&incoming_packet); + ucp = (u_char *) buffer_ptr(&incoming_packet); packet_length = GET_32BIT(ucp); if (packet_length < 1 + 4 || packet_length > 256 * 1024) { buffer_dump(&incoming_packet); @@ -868,14 +886,12 @@ * 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 - ); + macbuf = mac_compute(mac, seqnr, + (u_char *) 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) @@ -912,17 +928,17 @@ packet_length = 0; /* extract packet type */ - type = (unsigned char)buf[0]; + type = (u_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; - DBG(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); + DBG(debug("cipher_init receive_context")); + cipher_init(&receive_context, enc->cipher, + enc->key, enc->cipher->key_len, + enc->iv, enc->cipher->block_size); clear_enc_keys(enc, kex->we_need); if (comp->type != 0 && comp->enabled == 0) { comp->enabled = 1; @@ -932,10 +948,10 @@ } #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; + return (u_char)type; } int @@ -965,14 +981,15 @@ 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; default: return type; break; - } + } } else { switch(type) { case SSH_MSG_IGNORE: @@ -984,7 +1001,8 @@ 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; @@ -993,7 +1011,7 @@ DBG(debug("received packet type %d", type)); return type; break; - } + } } } } @@ -1004,24 +1022,24 @@ */ 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 +u_int packet_get_char() { 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 +u_int packet_get_int() { return buffer_get_int(&incoming_packet); @@ -1067,7 +1085,7 @@ */ char * -packet_get_string(unsigned int *length_ptr) +packet_get_string(u_int *length_ptr) { return buffer_get_string(&incoming_packet, length_ptr); } @@ -1087,6 +1105,9 @@ 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); @@ -1179,14 +1200,21 @@ void packet_write_wait() { + 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. */ @@ -1211,45 +1239,45 @@ /* 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; + int lowdelay = IPTOS_LOWDELAY; + int throughput = IPTOS_THROUGHPUT; 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 (packet_connection_is_ipv4()) { + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, + (void *) &lowdelay, sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", + strerror(errno)); + } 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 (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, sizeof(throughput)) < 0) error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); @@ -1280,4 +1308,66 @@ log("packet_set_maxsize: setting to %d", s); max_packet_size = s; return s; +} + +/* + * 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. + */ +/* size of current + ignore message should be n*sumlen bytes (w/o mac) */ +void +packet_inject_ignore(int sumlen) +{ + int blocksize, padlen, have, need, nb, mini, nbytes; + Enc *enc = NULL; + + if (use_ssh2_packet_format == 0) + return; + + have = buffer_len(&outgoing_packet); + debug2("packet_inject_ignore: current %d", have); + if (kex != NULL) + enc = &kex->enc[MODE_OUT]; + blocksize = enc ? enc->cipher->block_size : 8; + padlen = blocksize - (have % blocksize); + if (padlen < 4) + padlen += blocksize; + have += padlen; + have /= blocksize; /* # of blocks for current message */ + + nb = roundup(sumlen, blocksize) / blocksize; /* blocks for both */ + mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */ + need = nb - (have % nb); /* blocks for ignore */ + if (need <= mini) + need += nb; + nbytes = (need - mini) * blocksize; /* size of ignore payload */ + debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d", + blocksize, have, nb, mini, need); + + /* enqueue current message and append a ignore message */ + packet_send(); + packet_send_ignore(nbytes); +} + +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; + } }