| /* |
| * 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 1.60 2001/04/05 10:39:03 markus Exp $"); |
| |
| #include "xmalloc.h" |
| #include "buffer.h" |
| #include "packet.h" |
| #include "bufaux.h" |
| #include "crc32.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" |
| |
| #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 u_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; |
| static int compression_buffer_ready = 0; |
| |
| /* 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 */ |
| Newkeys *newkeys[MODE_MAX]; |
| |
| void |
| packet_set_ssh2_format(void) |
| { |
| DBG(debug("use_ssh2_packet_format")); |
| use_ssh2_packet_format = 1; |
| newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; |
| } |
| |
| /* |
| * 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, (u_char *) "", 0, NULL, 0); |
| cipher_init(&receive_context, none, (u_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 (compression_buffer_ready) { |
| buffer_free(&compression_buffer); |
| buffer_compress_uninit(); |
| } |
| } |
| |
| /* Sets remote side protocol flags. */ |
| |
| void |
| 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. */ |
| |
| u_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_init_compression() |
| { |
| if (compression_buffer_ready == 1) |
| return; |
| compression_buffer_ready = 1; |
| buffer_init(&compression_buffer); |
| } |
| |
| void |
| packet_start_compression(int level) |
| { |
| if (packet_compression && !use_ssh2_packet_format) |
| fatal("Compression already enabled."); |
| packet_compression = 1; |
| packet_init_compression(); |
| buffer_compress_init_send(level); |
| buffer_compress_init_recv(); |
| } |
| |
| /* |
| * 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, |
| u_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, u_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 u_char *key, u_int keylen, |
| int number) |
| { |
| Cipher *cipher = cipher_by_number(number); |
| if (cipher == NULL) |
| fatal("packet_set_encryption_key: unknown cipher number %d", number); |
| if (keylen < 20) |
| fatal("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(u_int value) |
| { |
| buffer_put_int(&outgoing_packet, value); |
| } |
| |
| /* Appends a string to packet data. */ |
| |
| void |
| packet_put_string(const char *buf, u_int len) |
| { |
| buffer_put_string(&outgoing_packet, buf, len); |
| } |
| void |
| packet_put_cstring(const char *str) |
| { |
| buffer_put_string(&outgoing_packet, str, strlen(str)); |
| } |
| |
| void |
| packet_put_raw(const char *buf, u_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(void) |
| { |
| char buf[8], *cp; |
| int i, padding, len; |
| u_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((u_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. |
| */ |
| } |
| |
| void |
| set_newkeys(int mode) |
| { |
| Enc *enc; |
| Mac *mac; |
| Comp *comp; |
| CipherContext *cc; |
| |
| debug("newkeys: mode %d", mode); |
| |
| cc = (mode == MODE_OUT) ? &send_context : &receive_context; |
| if (newkeys[mode] != NULL) { |
| debug("newkeys: rekeying"); |
| /* todo: free old keys, reset compression/cipher-ctxt; */ |
| memset(cc, 0, sizeof(*cc)); |
| enc = &newkeys[mode]->enc; |
| mac = &newkeys[mode]->mac; |
| comp = &newkeys[mode]->comp; |
| memset(mac->key, 0, mac->key_len); |
| xfree(enc->name); |
| xfree(enc->iv); |
| xfree(enc->key); |
| xfree(mac->name); |
| xfree(mac->key); |
| xfree(comp->name); |
| xfree(newkeys[mode]); |
| } |
| newkeys[mode] = kex_get_newkeys(mode); |
| if (newkeys[mode] == NULL) |
| fatal("newkeys: no keys for mode %d", mode); |
| enc = &newkeys[mode]->enc; |
| mac = &newkeys[mode]->mac; |
| comp = &newkeys[mode]->comp; |
| if (mac->md != NULL) |
| mac->enabled = 1; |
| DBG(debug("cipher_init_context: %d", mode)); |
| cipher_init(cc, enc->cipher, enc->key, enc->cipher->key_len, |
| enc->iv, enc->cipher->block_size); |
| memset(enc->iv, 0, enc->cipher->block_size); |
| memset(enc->key, 0, enc->cipher->key_len); |
| if (comp->type != 0 && comp->enabled == 0) { |
| packet_init_compression(); |
| if (mode == MODE_OUT) |
| buffer_compress_init_send(6); |
| else |
| buffer_compress_init_recv(); |
| comp->enabled = 1; |
| } |
| } |
| |
| /* |
| * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) |
| */ |
| void |
| packet_send2(void) |
| { |
| static u_int32_t seqnr = 0; |
| u_char *macbuf = NULL; |
| char *cp; |
| u_int packet_length = 0; |
| u_int i, padlen, len; |
| u_int32_t rand = 0; |
| int type; |
| 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->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 = mac_compute(mac, seqnr, |
| (u_char *) buffer_ptr(&outgoing_packet), |
| buffer_len(&outgoing_packet)); |
| DBG(debug("done calc MAC out #%d", seqnr)); |
| } |
| /* encrypt packet and append to output buffer. */ |
| buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); |
| 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) |
| set_newkeys(MODE_OUT); |
| } |
| |
| 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 *setp; |
| char buf[8192]; |
| DBG(debug("packet_read()")); |
| |
| setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * |
| sizeof(fd_mask)); |
| |
| /* Since we are blocking, ensure that all written packets have been sent. */ |
| packet_write_wait(); |
| |
| /* Stay in the loop until we have received a complete packet. */ |
| for (;;) { |
| /* Try to read a packet from the buffer. */ |
| type = packet_read_poll(payload_len_ptr); |
| if (!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) { |
| xfree(setp); |
| return type; |
| } |
| /* |
| * Otherwise, wait for some data to arrive, add it to the |
| * buffer, and try again. |
| */ |
| memset(setp, 0, howmany(connection_in + 1, NFDBITS) * |
| sizeof(fd_mask)); |
| FD_SET(connection_in, setp); |
| |
| /* Wait for some data to arrive. */ |
| 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) { |
| 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) |
| { |
| u_int len, padded_len; |
| u_char *ucp; |
| char buf[8], *cp; |
| u_int checksum, stored_checksum; |
| |
| /* Check if input size is less than minimum packet size. */ |
| if (buffer_len(&input) < 4 + 8) |
| return SSH_MSG_NONE; |
| /* Get length of incoming packet. */ |
| ucp = (u_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((u_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 = (u_char *) buffer_ptr(&incoming_packet) + len - 4; |
| stored_checksum = GET_32BIT(ucp); |
| if (checksum != stored_checksum) |
| packet_disconnect("Corrupted check bytes on input."); |
| buffer_consume_end(&incoming_packet, 4); |
| |
| /* If using packet compression, decompress the packet. */ |
| if (packet_compression) { |
| buffer_clear(&compression_buffer); |
| buffer_uncompress(&incoming_packet, &compression_buffer); |
| 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 (u_char) buf[0]; |
| } |
| |
| int |
| packet_read_poll2(int *payload_len_ptr) |
| { |
| static u_int32_t seqnr = 0; |
| static u_int packet_length = 0; |
| u_int padlen, need; |
| u_char buf[8], *macbuf; |
| u_char *ucp; |
| char *cp; |
| int 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->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 = (u_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 = mac_compute(mac, seqnr, |
| (u_char *) buffer_ptr(&incoming_packet), |
| buffer_len(&incoming_packet)); |
| if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) |
| packet_disconnect("Corrupted 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 = (u_char)buf[0]; |
| |
| 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 |
| return (u_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 from %s: %d: %.400s", get_remote_ipaddr(), |
| reason, msg); |
| xfree(msg); |
| fatal_cleanup(); |
| break; |
| default: |
| return type; |
| break; |
| } |
| } else { |
| switch(type) { |
| case SSH_MSG_IGNORE: |
| 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 != 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, u_int len) |
| { |
| buffer_append(&input, buf, len); |
| } |
| |
| /* Returns a character from the packet. */ |
| |
| u_int |
| packet_get_char() |
| { |
| char ch; |
| buffer_get(&incoming_packet, &ch, 1); |
| return (u_char) ch; |
| } |
| |
| /* Returns an integer from the packet data. */ |
| |
| u_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(u_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; |
| |
| if (compat20 && (datafellows & SSH_BUG_DEBUG)) |
| return; |
| |
| 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() |
| { |
| fd_set *setp; |
| |
| setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * |
| sizeof(fd_mask)); |
| packet_write_poll(); |
| while (packet_have_data_to_write()) { |
| 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() |
| { |
| 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) |
| { |
| static int called = 0; |
| #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) |
| int lowdelay = IPTOS_LOWDELAY; |
| int throughput = IPTOS_THROUGHPUT; |
| #endif |
| int on = 1; |
| |
| if (called) |
| return; |
| called = 1; |
| |
| /* Record that we are in interactive mode. */ |
| interactive_mode = interactive; |
| |
| /* Only set socket options if using a socket. */ |
| if (!packet_connection_is_on_socket()) |
| return; |
| /* |
| * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only |
| */ |
| if (interactive) { |
| /* |
| * Set IP options for an interactive connection. Use |
| * IPTOS_LOWDELAY and TCP_NODELAY. |
| */ |
| #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) |
| if (packet_connection_is_ipv4()) { |
| if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, |
| (void *) &lowdelay, sizeof(lowdelay)) < 0) |
| error("setsockopt IPTOS_LOWDELAY: %.100s", |
| strerror(errno)); |
| } |
| #endif |
| if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, |
| sizeof(on)) < 0) |
| error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); |
| } else if (packet_connection_is_ipv4()) { |
| /* |
| * Set IP options for a non-interactive connection. Use |
| * IPTOS_THROUGHPUT. |
| */ |
| #if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) |
| if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, |
| sizeof(throughput)) < 0) |
| error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); |
| #endif |
| } |
| } |
| |
| /* Returns true if the current connection is interactive. */ |
| |
| int |
| packet_is_interactive() |
| { |
| 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; |
| } |
| |
| /* |
| * 9.2. Ignored Data Message |
| * |
| * byte SSH_MSG_IGNORE |
| * string data |
| * |
| * All implementations MUST understand (and ignore) this message at any |
| * time (after receiving the protocol version). No implementation is |
| * required to send them. This message can be used as an additional |
| * protection measure against advanced traffic analysis techniques. |
| */ |
| /* size of current + ignore message should be n*sumlen bytes (w/o mac) */ |
| void |
| packet_inject_ignore(int sumlen) |
| { |
| int blocksize, padlen, have, need, nb, mini, nbytes; |
| Enc *enc = NULL; |
| |
| if (use_ssh2_packet_format == 0) |
| return; |
| |
| have = buffer_len(&outgoing_packet); |
| debug2("packet_inject_ignore: current %d", have); |
| if (newkeys[MODE_OUT] != NULL) |
| enc = &newkeys[MODE_OUT]->enc; |
| blocksize = enc ? enc->cipher->block_size : 8; |
| padlen = blocksize - (have % blocksize); |
| if (padlen < 4) |
| padlen += blocksize; |
| have += padlen; |
| have /= blocksize; /* # of blocks for current message */ |
| |
| nb = roundup(sumlen, blocksize) / blocksize; /* blocks for both */ |
| mini = roundup(5+1+4+4, blocksize) / blocksize; /* minsize ignore msg */ |
| need = nb - (have % nb); /* blocks for ignore */ |
| if (need <= mini) |
| need += nb; |
| nbytes = (need - mini) * blocksize; /* size of ignore payload */ |
| debug2("packet_inject_ignore: block %d have %d nb %d mini %d need %d", |
| blocksize, have, nb, mini, need); |
| |
| /* enqueue current message and append a ignore message */ |
| packet_send(); |
| packet_send_ignore(nbytes); |
| } |
| |
| void |
| packet_send_ignore(int nbytes) |
| { |
| u_int32_t rand = 0; |
| int i; |
| |
| packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); |
| packet_put_int(nbytes); |
| for(i = 0; i < nbytes; i++) { |
| if (i % 4 == 0) |
| rand = arc4random(); |
| packet_put_char(rand & 0xff); |
| rand >>= 8; |
| } |
| } |