diff options
Diffstat (limited to 'crypto/openssh/packet.c')
| -rw-r--r-- | crypto/openssh/packet.c | 1297 |
1 files changed, 1297 insertions, 0 deletions
diff --git a/crypto/openssh/packet.c b/crypto/openssh/packet.c new file mode 100644 index 0000000..3216fda --- /dev/null +++ b/crypto/openssh/packet.c @@ -0,0 +1,1297 @@ +/* + * Author: Tatu Ylonen <ylo@cs.hut.fi> + * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland + * All rights reserved + * 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("$OpenBSD: packet.c,v 1.38 2000/10/12 14:21:12 markus Exp $"); + +#include "xmalloc.h" +#include "buffer.h" +#include "packet.h" +#include "bufaux.h" +#include "ssh.h" +#include "crc32.h" +#include "getput.h" + +#include "compress.h" +#include "deattack.h" +#include "channels.h" + +#include "compat.h" +#include "ssh2.h" + +#include <openssl/bn.h> +#include <openssl/dh.h> +#include <openssl/hmac.h> +#include "buffer.h" +#include "cipher.h" +#include "kex.h" +#include "hmac.h" + +#ifdef PACKET_DEBUG +#define DBG(x) x +#else +#define DBG(x) +#endif + +/* + * This variable contains the file descriptors used for communicating with + * the other side. connection_in is used for reading; connection_out for + * writing. These can be the same descriptor, in which case it is assumed to + * be a socket. + */ +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; + +/* Encryption context for receiving data. This is only used for decryption. */ +static CipherContext receive_context; + +/* Encryption context for sending data. This is only used for encryption. */ +static CipherContext send_context; + +/* Buffer for raw input data from the socket. */ +static Buffer input; + +/* Buffer for raw output data going to the socket. */ +static Buffer output; + +/* Buffer for the partial outgoing packet being constructed. */ +static Buffer outgoing_packet; + +/* Buffer for the incoming packet currently being processed. */ +static Buffer incoming_packet; + +/* Scratch buffer for packet compression/decompression. */ +static Buffer compression_buffer; + +/* Flag indicating whether packet compression/decompression is enabled. */ +static int packet_compression = 0; + +/* default maximum packet size */ +int max_packet_size = 32768; + +/* Flag indicating whether this module has been initialized. */ +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; + +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) +{ + DBG(debug("use_ssh2_packet_format")); + use_ssh2_packet_format = 1; +} + +/* + * 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_init(&send_context, none, (unsigned char *) "", 0, NULL, 0); + cipher_init(&receive_context, none, (unsigned char *) "", 0, NULL, 0); + if (!initialized) { + initialized = 1; + buffer_init(&input); + buffer_init(&output); + buffer_init(&outgoing_packet); + buffer_init(&incoming_packet); + } + /* Kludge: arrange the close function to be called from fatal(). */ + 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() +{ + 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() +{ + 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() +{ + /* Set the socket into non-blocking mode. */ + if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) + error("fcntl O_NONBLOCK: %.100s", strerror(errno)); + + if (connection_out != connection_in) { + if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) + error("fcntl O_NONBLOCK: %.100s", strerror(errno)); + } +} + +/* Returns the socket used for reading. */ + +int +packet_get_connection_in() +{ + return connection_in; +} + +/* Returns the descriptor used for writing. */ + +int +packet_get_connection_out() +{ + return connection_out; +} + +/* Closes the connection and clears and frees internal data structures. */ + +void +packet_close() +{ + if (!initialized) + return; + initialized = 0; + if (connection_in == connection_out) { + shutdown(connection_out, SHUT_RDWR); + close(connection_out); + } else { + close(connection_in); + close(connection_out); + } + buffer_free(&input); + buffer_free(&output); + buffer_free(&outgoing_packet); + buffer_free(&incoming_packet); + if (packet_compression) { + buffer_free(&compression_buffer); + buffer_compress_uninit(); + } +} + +/* Sets remote side protocol flags. */ + +void +packet_set_protocol_flags(unsigned 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() +{ + return remote_protocol_flags; +} + +/* + * Starts packet compression from the next packet on in both directions. + * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. + */ + +/*** XXXXX todo: kex means re-init */ +void +packet_start_compression(int level) +{ + if (packet_compression) + fatal("Compression already enabled."); + packet_compression = 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 *context, void *dest, void *src, unsigned int bytes) +{ + /* + * Cryptographic attack detector for ssh - Modifications for packet.c + * (C)1998 CORE-SDI, Buenos Aires Argentina Ariel Futoransky(futo@core-sdi.com) + */ + 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(context, dest, src, bytes); +} + +/* + * Causes any further packets to be encrypted using the given key. The same + * 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 number) +{ + 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(&receive_context, cipher, key, keylen, NULL, 0); + cipher_init(&send_context, cipher, key, keylen, NULL, 0); +} + +/* 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); +} + +void +packet_start2(int type) +{ + char buf[4+1+1]; + + 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); +} + +/* Appends a character to the packet data. */ + +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) +{ + buffer_put_int(&outgoing_packet, value); +} + +/* Appends a string to packet data. */ + +void +packet_put_string(const char *buf, unsigned int len) +{ + buffer_put_string(&outgoing_packet, buf, len); +} +void +packet_put_cstring(const char *str) +{ + buffer_put_string(&outgoing_packet, str, strlen(str)); +} + +void +packet_put_raw(const char *buf, unsigned int len) +{ + buffer_append(&outgoing_packet, buf, len); +} + + +/* Appends an arbitrary precision integer to packet data. */ + +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_send1() +{ + char buf[8], *cp; + int i, padding, len; + unsigned int checksum; + u_int32_t rand = 0; + + /* + * If using packet compression, compress the payload of the outgoing + * packet. + */ + if (packet_compression) { + buffer_clear(&compression_buffer); + /* Skip padding. */ + buffer_consume(&outgoing_packet, 8); + /* padding */ + buffer_append(&compression_buffer, "\0\0\0\0\0\0\0\0", 8); + buffer_compress(&outgoing_packet, &compression_buffer); + buffer_clear(&outgoing_packet); + buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + } + /* Compute packet length without padding (add checksum, remove padding). */ + len = buffer_len(&outgoing_packet) + 4 - 8; + + /* Insert padding. Initialized to zero in packet_start1() */ + padding = 8 - len % 8; + if (cipher_type != SSH_CIPHER_NONE) { + cp = buffer_ptr(&outgoing_packet); + for (i = 0; i < padding; i++) { + if (i % 4 == 0) + rand = arc4random(); + cp[7 - i] = rand & 0xff; + rand >>= 8; + } + } + buffer_consume(&outgoing_packet, 8 - padding); + + /* Add check bytes. */ + checksum = ssh_crc32((unsigned char *) buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + PUT_32BIT(buf, checksum); + buffer_append(&outgoing_packet, buf, 4); + +#ifdef PACKET_DEBUG + fprintf(stderr, "packet_send plain: "); + buffer_dump(&outgoing_packet); +#endif + + /* 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)); + +#ifdef PACKET_DEBUG + fprintf(stderr, "encrypted: "); + buffer_dump(&output); +#endif + + buffer_clear(&outgoing_packet); + + /* + * Note that the packet is now only buffered in output. It won\'t be + * actually sent until packet_write_wait or packet_write_poll is + * called. + */ +} + +/* + * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) + */ +void +packet_send2() +{ + unsigned char *macbuf = NULL; + char *cp; + unsigned int packet_length = 0; + unsigned int i, padlen, 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]; + } + block_size = enc ? enc->cipher->block_size : 8; + + cp = buffer_ptr(&outgoing_packet); + type = cp[5] & 0xff; + +#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; + buffer_append_space(&outgoing_packet, &cp, 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; + } + } 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; + 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 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), + 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) { + if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) + fatal("packet_send2: no KEX"); + if (mac->md != NULL) + mac->enabled = 1; + 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; + if (! packet_compression) + packet_start_compression(6); + } + } +} + +void +packet_send() +{ + if (use_ssh2_packet_format) + 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 + * be used during the interactive session. + */ + +int +packet_read(int *payload_len_ptr) +{ + int type, len; + fd_set set; + char buf[8192]; + DBG(debug("packet_read()")); + + /* 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 (!use_ssh2_packet_format && ( + 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); + /* If we got a packet, return it. */ + if (type != SSH_MSG_NONE) + 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); + + /* Wait for some data to arrive. */ + select(connection_in + 1, &set, NULL, NULL, NULL); + + /* Read data from the socket. */ + len = read(connection_in, buf, sizeof(buf)); + 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. */ + packet_process_incoming(buf, len); + } + /* NOTREACHED */ +} + +/* + * 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) +{ + int type; + + type = packet_read(payload_len_ptr); + if (type != expected_type) + packet_disconnect("Protocol error: expected packet type %d, got %d", + expected_type, type); +} + +/* Checks if a full packet is available in the data received so far via + * packet_process_incoming. If so, reads the packet; otherwise returns + * SSH_MSG_NONE. This does not wait for data from the connection. + * + * 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) +{ + unsigned int len, padded_len; + unsigned char *ucp; + char buf[8], *cp; + unsigned 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); + if (len < 1 + 2 + 2 || len > 256 * 1024) + packet_disconnect("Bad packet length %d.", len); + padded_len = (len + 8) & ~7; + + /* Check if the packet has been entirely received. */ + if (buffer_len(&input) < 4 + padded_len) + return SSH_MSG_NONE; + + /* The entire packet is in buffer. */ + + /* Consume packet length. */ + buffer_consume(&input, 4); + + /* Copy 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); + buffer_consume(&input, padded_len); + +#ifdef PACKET_DEBUG + fprintf(stderr, "read_poll plain: "); + buffer_dump(&incoming_packet); +#endif + + /* Compute packet checksum. */ + checksum = ssh_crc32((unsigned char *) 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)); + + ucp = (unsigned 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); + buffer_clear(&incoming_packet); + 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]; +} + +int +packet_read_poll2(int *payload_len_ptr) +{ + unsigned int padlen, need; + unsigned char buf[8], *macbuf; + unsigned char *ucp; + 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]; + } + maclen = mac && mac->enabled ? mac->mac_len : 0; + block_size = enc ? enc->cipher->block_size : 8; + + 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); + 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); + packet_length = GET_32BIT(ucp); + 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 + buffer_append_space(&incoming_packet, &cp, need); + packet_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 (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 == 0) + log("incoming seqnr wraps around"); + + /* get padlen */ + cp = buffer_ptr(&incoming_packet) + 4; + padlen = *cp & 0xff; + 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) + */ + 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; + 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; + if (! packet_compression) + packet_start_compression(6); + } + } + +#ifdef PACKET_DEBUG + fprintf(stderr, "read/plain[%d]:\r\n",type); + buffer_dump(&incoming_packet); +#endif + return (unsigned char)type; +} + +int +packet_read_poll(int *payload_len_ptr) +{ + 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) + 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: %d: %.900s", reason, msg); + xfree(msg); + fatal_cleanup(); + break; + default: + return type; + break; + } + } else { + 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: %.900s", msg); + fatal_cleanup(); + xfree(msg); + break; + default: + if (type != 0) + DBG(debug("received packet type %d", type)); + return type; + break; + } + } + } +} + +/* + * 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) +{ + buffer_append(&input, buf, len); +} + +/* Returns a character from the packet. */ + +unsigned int +packet_get_char() +{ + char ch; + buffer_get(&incoming_packet, &ch, 1); + return (unsigned char) ch; +} + +/* Returns an integer from the packet data. */ + +unsigned int +packet_get_int() +{ + return buffer_get_int(&incoming_packet); +} + +/* + * Returns an arbitrary precision integer from the packet data. The integer + * must have been initialized before this call. + */ + +void +packet_get_bignum(BIGNUM * value, int *length_ptr) +{ + *length_ptr = buffer_get_bignum(&incoming_packet, value); +} + +void +packet_get_bignum2(BIGNUM * value, int *length_ptr) +{ + *length_ptr = buffer_get_bignum2(&incoming_packet, value); +} + +char * +packet_get_raw(int *length_ptr) +{ + 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); +} + +/* + * 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 + * no longer needed. The length_ptr argument may be NULL, or point to an + * integer into which the length of the string is stored. + */ + +char * +packet_get_string(unsigned int *length_ptr) +{ + return buffer_get_string(&incoming_packet, length_ptr); +} + +/* + * Sends a diagnostic message from the server to the client. This message + * can be sent at any time (but not while constructing another message). The + * message is printed immediately, but only if the client is being executed + * in verbose mode. These messages are primarily intended to ease debugging + * authentication problems. The length of the formatted message must not + * exceed 1024 bytes. This will automatically call packet_write_wait. + */ + +void +packet_send_debug(const char *fmt,...) +{ + char buf[1024]; + va_list args; + + va_start(args, fmt); + vsnprintf(buf, sizeof(buf), fmt, args); + va_end(args); + + 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(); +} + +/* + * Logs the error plus constructs and sends a disconnect packet, closes the + * connection, and exits. This function never returns. The error message + * should not contain a newline. The length of the formatted message must + * not exceed 1024 bytes. + */ + +void +packet_disconnect(const char *fmt,...) +{ + char buf[1024]; + va_list args; + static int disconnecting = 0; + if (disconnecting) /* Guard against recursive invocations. */ + fatal("packet_disconnect called recursively."); + disconnecting = 1; + + /* + * Format the message. Note that the caller must make sure the + * message is of limited size. + */ + va_start(args, fmt); + vsnprintf(buf, sizeof(buf), fmt, args); + va_end(args); + + /* Send the disconnect message to the other side, and wait for it to get sent. */ + 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_string(buf, strlen(buf)); + } + packet_send(); + packet_write_wait(); + + /* Stop listening for connections. */ + channel_stop_listening(); + + /* Close the connection. */ + packet_close(); + + /* Display the error locally and exit. */ + 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() +{ + int len = buffer_len(&output); + if (len > 0) { + len = write(connection_out, buffer_ptr(&output), len); + if (len <= 0) { + if (errno == EAGAIN) + return; + else + fatal("Write failed: %.100s", strerror(errno)); + } + buffer_consume(&output, len); + } +} + +/* + * Calls packet_write_poll repeatedly until all pending output data has been + * written. + */ + +void +packet_write_wait() +{ + 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); + packet_write_poll(); + } +} + +/* Returns true if there is buffered data to write to the connection. */ + +int +packet_have_data_to_write() +{ + return buffer_len(&output) != 0; +} + +/* Returns true if there is not too much data to write to the connection. */ + +int +packet_not_very_much_data_to_write() +{ + if (interactive_mode) + return buffer_len(&output) < 16384; + else + return buffer_len(&output) < 128 * 1024; +} + +/* Informs that the current session is interactive. Sets IP flags for that. */ + +void +packet_set_interactive(int interactive, int keepalives) +{ + int on = 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 + */ + 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 (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, + sizeof(on)) < 0) + error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); + } else { + /* + * 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)); + } +} + +/* Returns true if the current connection is interactive. */ + +int +packet_is_interactive() +{ + return interactive_mode; +} + +int +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); + 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); + max_packet_size = s; + return s; +} |
