X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/aa3378df3cc7da00b8f93569d0c88f0c626ddb18..db518d9b6f0e149631deb137bb00841f93b0d6d8:/packet.c diff --git a/packet.c b/packet.c index bc6d97f2..045d5a10 100644 --- a/packet.c +++ b/packet.c @@ -1,33 +1,71 @@ /* - * - * 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 1.90 2002/02/27 21:23:13 stevesk Exp $"); #include "xmalloc.h" #include "buffer.h" #include "packet.h" #include "bufaux.h" -#include "ssh.h" #include "crc32.h" -#include "cipher.h" #include "getput.h" #include "compress.h" #include "deattack.h" +#include "channels.h" + +#include "compat.h" +#include "ssh1.h" +#include "ssh2.h" + +#include "cipher.h" +#include "kex.h" +#include "mac.h" +#include "log.h" +#include "canohost.h" +#include "misc.h" + +#ifdef PACKET_DEBUG +#define DBG(x) x +#else +#define DBG(x) +#endif /* * This variable contains the file descriptors used for communicating with @@ -38,14 +76,8 @@ RCSID("$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; @@ -67,6 +99,7 @@ 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; @@ -80,19 +113,27 @@ static int initialized = 0; /* Set to true if the connection is interactive. */ static int interactive_mode = 0; +/* Session key information for Encryption and MAC */ +Newkeys *newkeys[MODE_MAX]; + +/* roundup current message to extra_pad bytes */ +static u_char extra_pad = 0; + /* * Sets the descriptors used for communication. Disables encryption until * packet_set_encryption_key is called. */ - 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_ENCRYPT); + cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); + newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; if (!initialized) { initialized = 1; buffer_init(&input); @@ -104,10 +145,52 @@ packet_set_connection(int fd_in, int fd_out) fatal_add_cleanup((void (*) (void *)) packet_close, NULL); } +/* Returns 1 if remote host is connected via socket, 0 if not. */ + +int +packet_connection_is_on_socket(void) +{ + struct sockaddr_storage from, to; + socklen_t fromlen, tolen; + + /* filedescriptors in and out are the same, so it's a socket */ + if (connection_in == connection_out) + return 1; + fromlen = sizeof(from); + memset(&from, 0, sizeof(from)); + if (getpeername(connection_in, (struct sockaddr *)&from, &fromlen) < 0) + return 0; + tolen = sizeof(to); + memset(&to, 0, sizeof(to)); + if (getpeername(connection_out, (struct sockaddr *)&to, &tolen) < 0) + return 0; + if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0) + return 0; + if (from.ss_family != AF_INET && from.ss_family != AF_INET6) + return 0; + return 1; +} + +/* returns 1 if connection is via ipv4 */ + +int +packet_connection_is_ipv4(void) +{ + struct sockaddr_storage to; + socklen_t tolen = sizeof(to); + + memset(&to, 0, sizeof(to)); + if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) + return 0; + if (to.ss_family != AF_INET) + return 0; + return 1; +} + /* 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) @@ -122,7 +205,7 @@ packet_set_nonblocking() /* Returns the socket used for reading. */ int -packet_get_connection_in() +packet_get_connection_in(void) { return connection_in; } @@ -130,7 +213,7 @@ packet_get_connection_in() /* Returns the descriptor used for writing. */ int -packet_get_connection_out() +packet_get_connection_out(void) { return connection_out; } @@ -138,7 +221,7 @@ packet_get_connection_out() /* Closes the connection and clears and frees internal data structures. */ void -packet_close() +packet_close(void) { if (!initialized) return; @@ -154,25 +237,26 @@ 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(); } + cipher_cleanup(&send_context); + cipher_cleanup(&receive_context); } /* 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; } @@ -182,60 +266,24 @@ packet_get_protocol_flags() * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ -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) - */ - - switch (cc->type) { - case SSH_CIPHER_NONE: - i = DEATTACK_OK; - break; - default: - i = detect_attack(src, bytes, NULL); - break; - } - - 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(); } /* @@ -243,73 +291,83 @@ 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) { - /* 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); + Cipher *cipher = cipher_by_number(number); + if (cipher == NULL) + fatal("packet_set_encryption_key: unknown cipher number %d", number); + if (keylen < 20) + fatal("packet_set_encryption_key: keylen too small: %d", keylen); + cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); + cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); } -/* Starts constructing a packet to send. */ - +/* Start constructing a packet to send. */ void -packet_start(int type) +packet_start(u_char type) { - char buf[9]; + 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, 8); - buf[8] = type; - buffer_append(&outgoing_packet, buf, 9); + 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); } - -/* Appends an arbitrary precision integer to packet data. */ - +void +packet_put_cstring(const char *str) +{ + buffer_put_cstring(&outgoing_packet, str); +} +void +packet_put_raw(const void *buf, u_int len) +{ + buffer_append(&outgoing_packet, buf, len); +} void packet_put_bignum(BIGNUM * value) { buffer_put_bignum(&outgoing_packet, value); } +void +packet_put_bignum2(BIGNUM * value) +{ + buffer_put_bignum2(&outgoing_packet, value); +} /* * Finalizes and sends the packet. If the encryption key has been set, * encrypts the packet before sending. */ -void -packet_send() +static void +packet_send1(void) { - char buf[8], *cp; + u_char buf[8], *cp; int i, padding, len; - unsigned int checksum; + u_int checksum; u_int32_t rand = 0; /* @@ -325,14 +383,14 @@ packet_send() 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.plaintext) { cp = buffer_ptr(&outgoing_packet); for (i = 0; i < padding; i++) { if (i % 4 == 0) @@ -344,8 +402,8 @@ packet_send() 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); @@ -357,9 +415,9 @@ packet_send() /* 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_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); @@ -375,6 +433,184 @@ packet_send() */ } +static void +set_newkeys(int mode) +{ + Enc *enc; + Mac *mac; + Comp *comp; + CipherContext *cc; + int encrypt; + + debug("newkeys: mode %d", mode); + + if (mode == MODE_OUT) { + cc = &send_context; + encrypt = CIPHER_ENCRYPT; + } else { + cc = &receive_context; + encrypt = CIPHER_DECRYPT; + } + if (newkeys[mode] != NULL) { + debug("newkeys: rekeying"); + cipher_cleanup(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->key_len, + enc->iv, enc->block_size, encrypt); + memset(enc->iv, 0, enc->block_size); + memset(enc->key, 0, enc->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) + */ +static void +packet_send2(void) +{ + static u_int32_t seqnr = 0; + u_char type, *cp, *macbuf = NULL; + u_char padlen, pad; + u_int packet_length = 0; + u_int i, len; + u_int32_t rand = 0; + Enc *enc = NULL; + Mac *mac = NULL; + Comp *comp = NULL; + int block_size; + + 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; + + cp = buffer_ptr(&outgoing_packet); + type = cp[5]; + +#ifdef PACKET_DEBUG + fprintf(stderr, "plain: "); + buffer_dump(&outgoing_packet); +#endif + + if (comp && comp->enabled) { + len = buffer_len(&outgoing_packet); + /* skip header, compress only payload */ + buffer_consume(&outgoing_packet, 5); + buffer_clear(&compression_buffer); + buffer_compress(&outgoing_packet, &compression_buffer); + buffer_clear(&outgoing_packet); + buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); + buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + DBG(debug("compression: raw %d compressed %d", len, + buffer_len(&outgoing_packet))); + } + + /* sizeof (packet_len + pad_len + payload) */ + len = buffer_len(&outgoing_packet); + + /* + * calc size of padding, alloc space, get random data, + * minimum padding is 4 bytes + */ + padlen = block_size - (len % block_size); + if (padlen < 4) + padlen += block_size; + 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 && !send_context.plaintext) { + /* random padding */ + for (i = 0; i < padlen; i++) { + if (i % 4 == 0) + rand = arc4random(); + cp[i] = rand & 0xff; + 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; + 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 = 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. */ + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + /* append unencrypted MAC */ + if (mac && mac->enabled) + buffer_append(&output, (char *)macbuf, mac->mac_len); +#ifdef PACKET_DEBUG + fprintf(stderr, "encrypted: "); + buffer_dump(&output); +#endif + /* increment sequence number for outgoing packets */ + if (++seqnr == 0) + log("outgoing seqnr wraps around"); + buffer_clear(&outgoing_packet); + + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_OUT); +} + +void +packet_send(void) +{ + if (compat20) + packet_send2(); + else + packet_send1(); + DBG(debug("packet_send done")); +} + /* * 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 @@ -382,11 +618,15 @@ packet_send() */ 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(); @@ -394,29 +634,37 @@ packet_read(int *payload_len_ptr) /* 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)); - if (len == 0) - fatal("Connection closed by %.200s", get_remote_ipaddr()); + if (len == 0) { + log("Connection closed by %.200s", get_remote_ipaddr()); + fatal_cleanup(); + } if (len < 0) fatal("Read from socket failed: %.100s", strerror(errno)); /* Append it to the buffer. */ @@ -425,20 +673,26 @@ 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); + expected_type, type); } /* Checks if a full packet is available in the data received so far via @@ -448,30 +702,21 @@ 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_poll(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; - -restart: + u_int len, padded_len; + u_char *cp, type; + 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); - len = GET_32BIT(ucp); + cp = buffer_ptr(&input); + len = GET_32BIT(cp); if (len < 1 + 2 + 2 || len > 256 * 1024) packet_disconnect("Bad packet length %d.", len); padded_len = (len + 8) & ~7; @@ -485,10 +730,20 @@ restart: /* 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.plaintext && + 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_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); + buffer_consume(&input, padded_len); #ifdef PACKET_DEBUG @@ -497,53 +752,218 @@ restart: #endif /* Compute packet checksum. */ - checksum = crc32((unsigned char *) buffer_ptr(&incoming_packet), - buffer_len(&incoming_packet) - 4); + 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.", - len, buffer_len(&incoming_packet)); + packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", + len, buffer_len(&incoming_packet)); - ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4; - stored_checksum = GET_32BIT(ucp); + cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; + stored_checksum = GET_32BIT(cp); 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); buffer_clear(&incoming_packet); buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), - buffer_len(&compression_buffer)); + buffer_len(&compression_buffer)); } - /* Get packet type. */ - buffer_get(&incoming_packet, &buf[0], 1); + type = buffer_get_char(&incoming_packet); + return type; +} - /* Return length of payload (without type field). */ - *payload_len_ptr = buffer_len(&incoming_packet); +static int +packet_read_poll2(u_int32_t *seqnr_p) +{ + static u_int32_t seqnr = 0; + static u_int packet_length = 0; + u_int padlen, need; + u_char *macbuf, *cp, type; + int maclen, block_size; + Enc *enc = NULL; + Mac *mac = NULL; + Comp *comp = NULL; + + 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; - /* Handle disconnect message. */ - if ((unsigned char) buf[0] == SSH_MSG_DISCONNECT) - fatal("Received disconnect: %.900s", packet_get_string(NULL)); + if (packet_length == 0) { + /* + * check if input size is less than the cipher block size, + * decrypt first block and extract length of incoming packet + */ + if (buffer_len(&input) < block_size) + return SSH_MSG_NONE; + buffer_clear(&incoming_packet); + cp = buffer_append_space(&incoming_packet, block_size); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), + block_size); + cp = buffer_ptr(&incoming_packet); + packet_length = GET_32BIT(cp); + if (packet_length < 1 + 4 || packet_length > 256 * 1024) { + buffer_dump(&incoming_packet); + packet_disconnect("Bad packet length %d.", packet_length); + } + DBG(debug("input: packet len %d", packet_length+4)); + buffer_consume(&input, block_size); + } + /* we have a partial packet of block_size bytes */ + need = 4 + packet_length - block_size; + DBG(debug("partial packet %d, need %d, maclen %d", block_size, + need, maclen)); + if (need % block_size != 0) + fatal("padding error: need %d block %d mod %d", + need, block_size, need % block_size); + /* + * check if the entire packet has been received and + * decrypt into incoming_packet + */ + if (buffer_len(&input) < need + maclen) + return SSH_MSG_NONE; +#ifdef PACKET_DEBUG + fprintf(stderr, "read_poll enc/full: "); + buffer_dump(&input); +#endif + cp = buffer_append_space(&incoming_packet, need); + cipher_crypt(&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 = 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 MAC on input."); + DBG(debug("MAC #%d ok", seqnr)); + buffer_consume(&input, mac->mac_len); + } + if (seqnr_p != NULL) + *seqnr_p = seqnr; + if (++seqnr == 0) + log("incoming seqnr wraps around"); + + /* get padlen */ + cp = buffer_ptr(&incoming_packet); + padlen = cp[4]; + DBG(debug("input: padlen %d", padlen)); + if (padlen < 4) + packet_disconnect("Corrupted padlen %d on input.", padlen); + + /* skip packet size + padlen, discard padding */ + buffer_consume(&incoming_packet, 4 + 1); + buffer_consume_end(&incoming_packet, padlen); + + DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); + if (comp && comp->enabled) { + buffer_clear(&compression_buffer); + buffer_uncompress(&incoming_packet, &compression_buffer); + buffer_clear(&incoming_packet); + buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + DBG(debug("input: len after de-compress %d", buffer_len(&incoming_packet))); + } + /* + * get packet type, implies consume. + * return length of payload (without type field) + */ + 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); + buffer_dump(&incoming_packet); +#endif + /* reset for next packet */ + packet_length = 0; + return type; +} - /* Ignore ignore messages. */ - if ((unsigned char) buf[0] == SSH_MSG_IGNORE) - goto restart; +int +packet_read_poll_seqnr(u_int32_t *seqnr_p) +{ + int reason, seqnr; + u_char type; + char *msg; - /* Send debug messages as debugging output. */ - if ((unsigned char) buf[0] == SSH_MSG_DEBUG) { - debug("Remote: %.900s", packet_get_string(NULL)); - goto restart; + for (;;) { + if (compat20) { + type = packet_read_poll2(seqnr_p); + if (type) + DBG(debug("received packet type %d", type)); + switch (type) { + case SSH2_MSG_IGNORE: + break; + case SSH2_MSG_DEBUG: + packet_get_char(); + msg = packet_get_string(NULL); + debug("Remote: %.900s", msg); + xfree(msg); + msg = packet_get_string(NULL); + xfree(msg); + break; + case SSH2_MSG_DISCONNECT: + reason = packet_get_int(); + msg = packet_get_string(NULL); + 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 { + type = packet_read_poll1(); + switch (type) { + case SSH_MSG_IGNORE: + break; + case SSH_MSG_DEBUG: + msg = packet_get_string(NULL); + debug("Remote: %.900s", msg); + xfree(msg); + break; + case SSH_MSG_DISCONNECT: + msg = packet_get_string(NULL); + log("Received disconnect from %s: %.400s", get_remote_ipaddr(), + msg); + fatal_cleanup(); + xfree(msg); + break; + default: + if (type) + DBG(debug("received packet type %d", type)); + return type; + break; + } + } } - /* Return type. */ - return (unsigned char) buf[0]; +} + +int +packet_read_poll(void) +{ + return packet_read_poll_seqnr(NULL); } /* @@ -552,25 +972,25 @@ restart: */ 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); } @@ -581,9 +1001,30 @@ packet_get_int() */ void -packet_get_bignum(BIGNUM * value, int *length_ptr) +packet_get_bignum(BIGNUM * value) +{ + buffer_get_bignum(&incoming_packet, value); +} + +void +packet_get_bignum2(BIGNUM * value) +{ + buffer_get_bignum2(&incoming_packet, value); +} + +void * +packet_get_raw(int *length_ptr) { - *length_ptr = buffer_get_bignum(&incoming_packet, value); + int bytes = buffer_len(&incoming_packet); + if (length_ptr != NULL) + *length_ptr = bytes; + return buffer_ptr(&incoming_packet); +} + +int +packet_remaining(void) +{ + return buffer_len(&incoming_packet); } /* @@ -593,8 +1034,8 @@ packet_get_bignum(BIGNUM * value, 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); } @@ -614,12 +1055,22 @@ 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(); } @@ -650,25 +1101,33 @@ packet_disconnect(const char *fmt,...) va_end(args); /* Send the disconnect message to the other side, and wait for it to get sent. */ - packet_start(SSH_MSG_DISCONNECT); - packet_put_string(buf, strlen(buf)); + if (compat20) { + packet_start(SSH2_MSG_DISCONNECT); + packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR); + packet_put_cstring(buf); + packet_put_cstring(""); + } else { + packet_start(SSH_MSG_DISCONNECT); + packet_put_cstring(buf); + } packet_send(); packet_write_wait(); /* Stop listening for connections. */ - channel_stop_listening(); + channel_close_all(); /* Close the connection. */ packet_close(); /* Display the error locally and exit. */ - fatal("Disconnecting: %.100s", buf); + log("Disconnecting: %.100s", buf); + fatal_cleanup(); } /* 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) { @@ -689,22 +1148,29 @@ 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; } @@ -712,7 +1178,7 @@ 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; @@ -723,54 +1189,58 @@ 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) { - int on = 1; + static int called = 0; +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + int lowdelay = IPTOS_LOWDELAY; + int throughput = IPTOS_THROUGHPUT; +#endif + + 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; /* - * Only set socket options if using a socket (as indicated by the - * descriptors being the same). + * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only */ - if (connection_in != connection_out) - 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)); - } 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 (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, - sizeof(on)) < 0) - error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); - } else { +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + if (packet_connection_is_ipv4()) { + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, + &lowdelay, sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", + strerror(errno)); + } +#endif + set_nodelay(connection_in); + } 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) +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &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; } @@ -780,14 +1250,50 @@ packet_set_maxsize(int s) { static int called = 0; if (called) { - log("packet_set_maxsize: called twice: old %d new %d", max_packet_size, s); + log("packet_set_maxsize: called twice: old %d new %d", + max_packet_size, s); return -1; } if (s < 4 * 1024 || s > 1024 * 1024) { 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; + } +}