diff options
Diffstat (limited to 'crypto/openssh/packet.c')
| -rw-r--r-- | crypto/openssh/packet.c | 845 |
1 files changed, 0 insertions, 845 deletions
diff --git a/crypto/openssh/packet.c b/crypto/openssh/packet.c deleted file mode 100644 index af54759233b7..000000000000 --- a/crypto/openssh/packet.c +++ /dev/null @@ -1,845 +0,0 @@ -/* - * - * packet.c - * - * Author: Tatu Ylonen <ylo@cs.hut.fi> - * - * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, 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. - * - */ - -#include "includes.h" -RCSID("$Id: packet.c,v 1.22 2000/02/05 10:13:11 markus 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" - -/* - * 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; - -/* - * 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) -{ - 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); - 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. - */ - -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 * cc, void *dest, void *src, - unsigned 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) - */ - - 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); -} - -/* - * 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 cipher) -{ - /* All other ciphers use the same key in both directions for now. */ - cipher_set_key(&receive_context, cipher, key, keylen, 0); - cipher_set_key(&send_context, cipher, key, keylen, 1); -} - -/* Starts constructing a packet to send. */ - -void -packet_start(int type) -{ - char buf[9]; - - buffer_clear(&outgoing_packet); - memset(buf, 0, 8); - buf[8] = type; - buffer_append(&outgoing_packet, buf, 9); -} - -/* 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); -} - -/* Appends an arbitrary precision integer to packet data. */ - -void -packet_put_bignum(BIGNUM * value) -{ - buffer_put_bignum(&outgoing_packet, value); -} - -/* - * Finalizes and sends the packet. If the encryption key has been set, - * encrypts the packet before sending. - */ - -void -packet_send() -{ - 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. */ - 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 = 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. - */ -} - -/* - * 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]; - - /* Since we are blocking, ensure that all written packets have been sent. */ - packet_write_wait(); - - /* Stay in the loop until we have received a complete packet. */ - for (;;) { - /* Try to read a packet from the buffer. */ - type = packet_read_poll(payload_len_ptr); - if (type == SSH_SMSG_SUCCESS - || type == 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_poll(int *payload_len_ptr) -{ - unsigned int len, padded_len; - unsigned char *ucp; - char buf[8], *cp, *msg; - unsigned int checksum, stored_checksum; - -restart: - - /* 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 = 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); - - /* Handle disconnect message. */ - if ((unsigned char) buf[0] == SSH_MSG_DISCONNECT) { - msg = packet_get_string(NULL); - log("Received disconnect: %.900s", msg); - xfree(msg); - fatal_cleanup(); - } - - /* Ignore ignore messages. */ - if ((unsigned char) buf[0] == SSH_MSG_IGNORE) - goto restart; - - /* Send debug messages as debugging output. */ - if ((unsigned char) buf[0] == SSH_MSG_DEBUG) { - msg = packet_get_string(NULL); - debug("Remote: %.900s", msg); - xfree(msg); - goto restart; - } - /* Return type. */ - return (unsigned char) buf[0]; -} - -/* - * 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); -} - -/* - * 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); - - packet_start(SSH_MSG_DEBUG); - packet_put_string(buf, strlen(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. */ - 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; -} |