diff options
Diffstat (limited to 'usr/src/cmd/ssh/libssh/common/packet.c')
| -rw-r--r-- | usr/src/cmd/ssh/libssh/common/packet.c | 1608 |
1 files changed, 1608 insertions, 0 deletions
diff --git a/usr/src/cmd/ssh/libssh/common/packet.c b/usr/src/cmd/ssh/libssh/common/packet.c new file mode 100644 index 0000000000..10cf9bdc1b --- /dev/null +++ b/usr/src/cmd/ssh/libssh/common/packet.c @@ -0,0 +1,1608 @@ +/* + * 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, 2001 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +/* + * Copyright 2004 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#include "includes.h" +RCSID("$OpenBSD: packet.c,v 1.97 2002/07/04 08:12:15 deraadt Exp $"); + +#pragma ident "%Z%%M% %I% %E% SMI" + +#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" +#include "misc.h" +#include "ssh.h" + +#ifdef ALTPRIVSEP +static int packet_server = 0; +static int packet_monitor = 0; +#endif /* ALTPRIVSEP */ + +#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; + +/* 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. */ +Buffer input; + +/* Buffer for raw output data going to the socket. */ +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; + +/* Session key information for Encryption and MAC */ +Newkeys *newkeys[MODE_MAX]; +static u_int32_t read_seqnr = 0; +static u_int32_t send_seqnr = 0; + +/* Session key for protocol v1 */ +static u_char ssh1_key[SSH_SESSION_KEY_LENGTH]; +static u_int ssh1_keylen; + +/* roundup current message to extra_pad bytes */ +static u_char extra_pad = 0; + +/* + * Sets the descriptors used for communication. Disables encryption until + * packet_set_encryption_key is called. + */ +void +packet_set_connection(int fd_in, int fd_out) +{ + Cipher *none = cipher_by_name("none"); + + if (none == NULL) + fatal("packet_set_connection: cannot load cipher 'none'"); + connection_in = fd_in; + connection_out = fd_out; + cipher_init(&send_context, none, (unsigned char *) "", 0, NULL, 0, CIPHER_ENCRYPT); + cipher_init(&receive_context, none, (unsigned char *) "", 0, NULL, 0, CIPHER_DECRYPT); + newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; + if (!initialized) { + initialized = 1; + buffer_init(&input); + buffer_init(&output); + buffer_init(&outgoing_packet); + buffer_init(&incoming_packet); + } else { + buffer_clear(&input); + buffer_clear(&output); + buffer_clear(&outgoing_packet); + buffer_clear(&incoming_packet); + } + + /* + * Prime the cache for get_remote_ipaddr() while we have a + * socket on which to do a getpeername(). + */ + (void) get_remote_ipaddr(); + + /* 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(void) +{ + struct sockaddr_storage from, to; + socklen_t fromlen, tolen; + + /* filedescriptors in and out are the same, so it's a socket */ + if (connection_in != -1 && 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; +} + +/* + * Exports an IV from the CipherContext required to export the key + * state back from the unprivileged child to the privileged parent + * process. + */ + +void +packet_get_keyiv(int mode, u_char *iv, u_int len) +{ + CipherContext *cc; + + if (mode == MODE_OUT) + cc = &send_context; + else + cc = &receive_context; + + cipher_get_keyiv(cc, iv, len); +} + +int +packet_get_keycontext(int mode, u_char *dat) +{ + CipherContext *cc; + + if (mode == MODE_OUT) + cc = &send_context; + else + cc = &receive_context; + + return (cipher_get_keycontext(cc, dat)); +} + +void +packet_set_keycontext(int mode, u_char *dat) +{ + CipherContext *cc; + + if (mode == MODE_OUT) + cc = &send_context; + else + cc = &receive_context; + + cipher_set_keycontext(cc, dat); +} + +int +packet_get_keyiv_len(int mode) +{ + CipherContext *cc; + + if (mode == MODE_OUT) + cc = &send_context; + else + cc = &receive_context; + + return (cipher_get_keyiv_len(cc)); +} +void +packet_set_iv(int mode, u_char *dat) +{ + CipherContext *cc; + + if (mode == MODE_OUT) + cc = &send_context; + else + cc = &receive_context; + + cipher_set_keyiv(cc, dat); +} +int +packet_get_ssh1_cipher() +{ + return (cipher_get_number(receive_context.cipher)); +} + + +u_int32_t +packet_get_seqnr(int mode) +{ + return (mode == MODE_IN ? read_seqnr : send_seqnr); +} + +void +packet_set_seqnr(int mode, u_int32_t seqnr) +{ + if (mode == MODE_IN) + read_seqnr = seqnr; + else if (mode == MODE_OUT) + send_seqnr = seqnr; + else + fatal("packet_set_seqnr: bad mode %d", mode); +} + +/* returns 1 if connection is via ipv4 */ + +int +packet_connection_is_ipv4(void) +{ + struct sockaddr_storage to; + socklen_t tolen = sizeof(to); + + memset(&to, 0, sizeof(to)); + if (getsockname(connection_out, (struct sockaddr *)&to, &tolen) < 0) + return 0; + if (to.ss_family == AF_INET) + return 1; +#ifdef IPV4_IN_IPV6 + if (to.ss_family == AF_INET6 && + IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) + return 1; +#endif + return 0; +} + +/* Sets the connection into non-blocking mode. */ + +void +packet_set_nonblocking(void) +{ + /* 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(void) +{ + return connection_in; +} + +/* Returns the descriptor used for writing. */ + +int +packet_get_connection_out(void) +{ + return connection_out; +} + +/* Closes the connection and clears and frees internal data structures. */ + +void +packet_close(void) +{ + 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(); + compression_buffer_ready = 0; + } + cipher_cleanup(&send_context); + cipher_cleanup(&receive_context); +} + +/* Sets remote side protocol flags. */ + +void +packet_set_protocol_flags(u_int protocol_flags) +{ + remote_protocol_flags = protocol_flags; +} + +/* Returns the remote protocol flags set earlier by the above function. */ + +u_int +packet_get_protocol_flags(void) +{ + 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. + */ + +static void +packet_init_compression(void) +{ + if (compression_buffer_ready == 1) + return; + compression_buffer_ready = 1; + buffer_init(&compression_buffer); +} + +void +packet_start_compression(int level) +{ +#ifdef ALTPRIVSEP + /* shouldn't happen! */ + if (packet_monitor) + fatal("INTERNAL ERROR: The monitor cannot compress."); +#endif /* ALTPRIVSEP */ + + if (packet_compression && !compat20) + fatal("Compression already enabled."); + packet_compression = 1; + packet_init_compression(); + buffer_compress_init_send(level); + buffer_compress_init_recv(); +} + +/* + * 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); + if (keylen > SSH_SESSION_KEY_LENGTH) + fatal("packet_set_encryption_key: keylen too big: %d", keylen); + memcpy(ssh1_key, key, keylen); + ssh1_keylen = keylen; + cipher_init(&send_context, cipher, key, keylen, NULL, 0, CIPHER_ENCRYPT); + cipher_init(&receive_context, cipher, key, keylen, NULL, 0, CIPHER_DECRYPT); +} + +u_int +packet_get_encryption_key(u_char *key) +{ + if (key == NULL) + return (ssh1_keylen); + memcpy(key, ssh1_key, ssh1_keylen); + return (ssh1_keylen); +} + +/* Start constructing a packet to send. */ +void +packet_start(u_char type) +{ + u_char buf[9]; + int len; + + DBG(debug("packet_start[%d]", type)); + len = compat20 ? 6 : 9; + memset(buf, 0, len - 1); + buf[len - 1] = type; + buffer_clear(&outgoing_packet); + buffer_append(&outgoing_packet, buf, len); +} + +/* Append payload. */ +void +packet_put_char(int value) +{ + char ch = value; + + buffer_append(&outgoing_packet, &ch, 1); +} +void +packet_put_int(u_int value) +{ + buffer_put_int(&outgoing_packet, value); +} +void +packet_put_string(const void *buf, u_int len) +{ + buffer_put_string(&outgoing_packet, buf, len); +} +void +packet_put_cstring(const char *str) +{ + buffer_put_cstring(&outgoing_packet, str); +} +void +packet_put_ascii_cstring(const char *str) +{ + buffer_put_ascii_cstring(&outgoing_packet, str); +} +void +packet_put_utf8_cstring(const u_char *str) +{ + buffer_put_utf8_cstring(&outgoing_packet, str); +} +#if 0 +void +packet_put_ascii_string(const void *buf, u_int len) +{ + buffer_put_ascii_string(&outgoing_packet, buf, len); +} +void +packet_put_utf8_string(const void *buf, u_int len) +{ + buffer_put_utf8_string(&outgoing_packet, buf, len); +} +#endif +void +packet_put_raw(const void *buf, u_int len) +{ + buffer_append(&outgoing_packet, buf, len); +} +void +packet_put_bignum(BIGNUM * value) +{ + buffer_put_bignum(&outgoing_packet, value); +} +void +packet_put_bignum2(BIGNUM * value) +{ + buffer_put_bignum2(&outgoing_packet, value); +} + +/* + * Finalizes and sends the packet. If the encryption key has been set, + * encrypts the packet before sending. + */ + +static void +packet_send1(void) +{ + u_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 (!send_context.plaintext) { + 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(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); + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + +#ifdef PACKET_DEBUG + fprintf(stderr, "encrypted: "); + 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; + int encrypt; + + debug("newkeys: mode %d", mode); + + if (mode == MODE_OUT) { + cc = &send_context; + encrypt = CIPHER_ENCRYPT; + } else { + cc = &receive_context; + encrypt = CIPHER_DECRYPT; + } + if (newkeys[mode] != NULL) { + debug("newkeys: rekeying"); + cipher_cleanup(cc); + enc = &newkeys[mode]->enc; + mac = &newkeys[mode]->mac; + comp = &newkeys[mode]->comp; + memset(mac->key, 0, mac->key_len); + xfree(enc->name); + xfree(enc->iv); + xfree(enc->key); + xfree(mac->name); + xfree(mac->key); + xfree(comp->name); + xfree(newkeys[mode]); + } + newkeys[mode] = kex_get_newkeys(mode); + if (newkeys[mode] == NULL) + fatal("newkeys: no keys for mode %d", mode); + enc = &newkeys[mode]->enc; + mac = &newkeys[mode]->mac; + comp = &newkeys[mode]->comp; + if (mac->md != NULL) + mac->enabled = 1; + DBG(debug("cipher_init_context: %d", mode)); + cipher_init(cc, enc->cipher, enc->key, enc->key_len, + enc->iv, enc->block_size, encrypt); + /* Deleting the keys does not gain extra security */ + /* memset(enc->iv, 0, enc->block_size); + memset(enc->key, 0, enc->key_len); */ + if (comp->type != 0 && comp->enabled == 0) { + packet_init_compression(); + if (mode == MODE_OUT) + buffer_compress_init_send(6); + else + buffer_compress_init_recv(); + comp->enabled = 1; + } +} + +/* + * Finalize packet in SSH2 format (compress, mac, encrypt, enqueue) + */ +static void +packet_send2(void) +{ + u_char type, *cp, *macbuf = NULL; + u_char padlen, pad; + u_int packet_length = 0; + u_int i, len; + u_int32_t rand = 0; + Enc *enc = NULL; + Mac *mac = NULL; + Comp *comp = NULL; + int block_size; + + if (newkeys[MODE_OUT] != NULL) { + enc = &newkeys[MODE_OUT]->enc; + mac = &newkeys[MODE_OUT]->mac; + comp = &newkeys[MODE_OUT]->comp; + } + block_size = enc ? enc->block_size : 8; + + cp = buffer_ptr(&outgoing_packet); + type = cp[5]; + +#ifdef PACKET_DEBUG + fprintf(stderr, "plain: "); + buffer_dump(&outgoing_packet); +#endif + + if (comp && comp->enabled) { + len = buffer_len(&outgoing_packet); + /* skip header, compress only payload */ + buffer_consume(&outgoing_packet, 5); + buffer_clear(&compression_buffer); + buffer_compress(&outgoing_packet, &compression_buffer); + buffer_clear(&outgoing_packet); + buffer_append(&outgoing_packet, "\0\0\0\0\0", 5); + buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + DBG(debug("compression: raw %d compressed %d", len, + buffer_len(&outgoing_packet))); + } + + /* sizeof (packet_len + pad_len + payload) */ + len = buffer_len(&outgoing_packet); + + /* + * calc size of padding, alloc space, get random data, + * minimum padding is 4 bytes + */ + padlen = block_size - (len % block_size); + if (padlen < 4) + padlen += block_size; + if (extra_pad) { + /* will wrap if extra_pad+padlen > 255 */ + extra_pad = roundup(extra_pad, block_size); + pad = extra_pad - ((len + padlen) % extra_pad); + debug3("packet_send2: adding %d (len %d padlen %d extra_pad %d)", + pad, len, padlen, extra_pad); + padlen += pad; + extra_pad = 0; + } + cp = buffer_append_space(&outgoing_packet, padlen); + if (enc && !send_context.plaintext) { + /* random padding */ + for (i = 0; i < padlen; i++) { + if (i % 4 == 0) + rand = arc4random(); + cp[i] = rand & 0xff; + rand >>= 8; + } + } else { + /* clear padding */ + memset(cp, 0, padlen); + } + /* packet_length includes payload, padding and padding length field */ + packet_length = buffer_len(&outgoing_packet) - 4; + cp = buffer_ptr(&outgoing_packet); + PUT_32BIT(cp, packet_length); + cp[4] = padlen; + DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); + + /* compute MAC over seqnr and packet(length fields, payload, padding) */ + if (mac && mac->enabled) { + macbuf = mac_compute(mac, send_seqnr, + buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + DBG(debug("done calc MAC out #%d", send_seqnr)); + } + /* encrypt packet and append to output buffer. */ + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); + /* append unencrypted MAC */ + if (mac && mac->enabled) + buffer_append(&output, (char *)macbuf, mac->mac_len); +#ifdef PACKET_DEBUG + fprintf(stderr, "encrypted: "); + buffer_dump(&output); +#endif + /* increment sequence number for outgoing packets */ + if (++send_seqnr == 0) + log("outgoing seqnr wraps around"); + buffer_clear(&outgoing_packet); + + if (type == SSH2_MSG_NEWKEYS) +#ifdef ALTPRIVSEP + /* set_newkeys(MODE_OUT) in client, server, but not monitor */ + if (!packet_is_server() && !packet_is_monitor()) +#endif /* ALTPRIVSEP */ + set_newkeys(MODE_OUT); +} + +void +packet_send(void) +{ + if (compat20) + packet_send2(); + else + packet_send1(); + DBG(debug("packet_send done")); +} + +/* + * Waits until a packet has been received, and returns its type. Note that + * no other data is processed until this returns, so this function should not + * be used during the interactive session. + */ + +int +packet_read_seqnr(u_int32_t *seqnr_p) +{ + 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_seqnr(seqnr_p); + if (!compat20 && ( + type == SSH_SMSG_SUCCESS + || type == SSH_SMSG_FAILURE + || type == SSH_CMSG_EOF + || type == SSH_CMSG_EXIT_CONFIRMATION)) + packet_check_eom(); + /* 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 */ +} + +int +packet_read(void) +{ + return packet_read_seqnr(NULL); +} + +/* + * Waits until a packet has been received, verifies that its type matches + * that given, and gives a fatal error and exits if there is a mismatch. + */ + +void +packet_read_expect(int expected_type) +{ + int type; + + type = packet_read(); + 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. + */ + +static int +packet_read_poll1(void) +{ + u_int len, padded_len; + u_char *cp, type; + u_int checksum, stored_checksum; + + /* Check if input size is less than minimum packet size. */ + if (buffer_len(&input) < 4 + 8) + return SSH_MSG_NONE; + /* Get length of incoming packet. */ + cp = buffer_ptr(&input); + len = GET_32BIT(cp); + if (len < 1 + 2 + 2 || len > 256 * 1024) + packet_disconnect("Bad packet length %d.", len); + padded_len = (len + 8) & ~7; + + /* 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); + + /* + * Cryptographic attack detector for ssh + * (C)1998 CORE-SDI, Buenos Aires Argentina + * Ariel Futoransky(futo@core-sdi.com) + */ + if (!receive_context.plaintext && + detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) + packet_disconnect("crc32 compensation attack: network attack detected"); + + /* Decrypt data to incoming_packet. */ + buffer_clear(&incoming_packet); + cp = buffer_append_space(&incoming_packet, padded_len); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); + + buffer_consume(&input, padded_len); + +#ifdef PACKET_DEBUG + fprintf(stderr, "read_poll plain: "); + buffer_dump(&incoming_packet); +#endif + + /* Compute packet checksum. */ + checksum = ssh_crc32(buffer_ptr(&incoming_packet), + buffer_len(&incoming_packet) - 4); + + /* Skip padding. */ + buffer_consume(&incoming_packet, 8 - len % 8); + + /* Test check bytes. */ + if (len != buffer_len(&incoming_packet)) + packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", + len, buffer_len(&incoming_packet)); + + cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; + stored_checksum = GET_32BIT(cp); + if (checksum != stored_checksum) + packet_disconnect("Corrupted check bytes on input."); + buffer_consume_end(&incoming_packet, 4); + + if (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)); + } + type = buffer_get_char(&incoming_packet); + return type; +} + +static int +packet_read_poll2(u_int32_t *seqnr_p) +{ + static u_int packet_length = 0; + u_int padlen, need; + u_char *macbuf, *cp, type; + int maclen, block_size; + Enc *enc = NULL; + Mac *mac = NULL; + Comp *comp = NULL; + + if (newkeys[MODE_IN] != NULL) { + enc = &newkeys[MODE_IN]->enc; + mac = &newkeys[MODE_IN]->mac; + comp = &newkeys[MODE_IN]->comp; + } + maclen = mac && mac->enabled ? mac->mac_len : 0; + block_size = enc ? enc->block_size : 8; + + if (packet_length == 0) { + /* + * check if input size is less than the cipher block size, + * decrypt first block and extract length of incoming packet + */ + if (buffer_len(&input) < block_size) + return SSH_MSG_NONE; + buffer_clear(&incoming_packet); + cp = buffer_append_space(&incoming_packet, block_size); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), + block_size); + cp = buffer_ptr(&incoming_packet); + packet_length = GET_32BIT(cp); + if (packet_length < 1 + 4 || packet_length > 256 * 1024) { + buffer_dump(&incoming_packet); + packet_disconnect("Bad packet length %d.", packet_length); + } + DBG(debug("input: packet len %d", packet_length+4)); + buffer_consume(&input, block_size); + } + /* we have a partial packet of block_size bytes */ + need = 4 + packet_length - block_size; + DBG(debug("partial packet %d, need %d, maclen %d", block_size, + need, maclen)); + if (need % block_size != 0) + fatal("padding error: need %d block %d mod %d", + need, block_size, need % block_size); + /* + * check if the entire packet has been received and + * decrypt into incoming_packet + */ + if (buffer_len(&input) < need + maclen) + return SSH_MSG_NONE; +#ifdef PACKET_DEBUG + fprintf(stderr, "read_poll enc/full: "); + buffer_dump(&input); +#endif + cp = buffer_append_space(&incoming_packet, need); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); + buffer_consume(&input, need); + /* + * compute MAC over seqnr and packet, + * increment sequence number for incoming packet + */ + if (mac && mac->enabled) { + macbuf = mac_compute(mac, read_seqnr, + buffer_ptr(&incoming_packet), + buffer_len(&incoming_packet)); + if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) + packet_disconnect("Corrupted MAC on input."); + DBG(debug("MAC #%d ok", read_seqnr)); + buffer_consume(&input, mac->mac_len); + } + if (seqnr_p != NULL) + *seqnr_p = read_seqnr; + if (++read_seqnr == 0) + log("incoming seqnr wraps around"); + + /* get padlen */ + cp = buffer_ptr(&incoming_packet); + padlen = cp[4]; + DBG(debug("input: padlen %d", padlen)); + if (padlen < 4) + packet_disconnect("Corrupted padlen %d on input.", padlen); + + /* skip packet size + padlen, discard padding */ + buffer_consume(&incoming_packet, 4 + 1); + buffer_consume_end(&incoming_packet, padlen); + + DBG(debug("input: len before de-compress %d", buffer_len(&incoming_packet))); + if (comp && comp->enabled) { + buffer_clear(&compression_buffer); + buffer_uncompress(&incoming_packet, &compression_buffer); + buffer_clear(&incoming_packet); + buffer_append(&incoming_packet, buffer_ptr(&compression_buffer), + buffer_len(&compression_buffer)); + DBG(debug("input: len after de-compress %d", + buffer_len(&incoming_packet))); + } + /* + * get packet type, implies consume. + * return length of payload (without type field) + */ + type = buffer_get_char(&incoming_packet); +#ifdef ALTPRIVSEP + if (type == SSH2_MSG_NEWKEYS) + /* set_newkeys(MODE_OUT) in client, server, but not monitor */ + if (!packet_is_server() && !packet_is_monitor()) + set_newkeys(MODE_IN); +#else /* ALTPRIVSEP */ + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_IN); +#endif /* ALTPRIVSEP */ +#ifdef PACKET_DEBUG + fprintf(stderr, "read/plain[%d]:\r\n", type); + buffer_dump(&incoming_packet); +#endif + /* reset for next packet */ + packet_length = 0; + return type; +} + +int +packet_read_poll_seqnr(u_int32_t *seqnr_p) +{ + u_int reason, seqnr; + u_char type; + char *msg; + + for (;;) { + if (compat20) { + type = packet_read_poll2(seqnr_p); + 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: %u: %.400s", + get_remote_ipaddr(), reason, msg); + xfree(msg); + fatal_cleanup(); + break; + case SSH2_MSG_UNIMPLEMENTED: + seqnr = packet_get_int(); + debug("Received SSH2_MSG_UNIMPLEMENTED for %u", + seqnr); + break; + default: + return type; + break; + } + } else { + type = packet_read_poll1(); + DBG(debug("received packet type %d", type)); + 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: + return type; + break; + } + } + } +} + +int +packet_read_poll(void) +{ + return packet_read_poll_seqnr(NULL); +} + +/* + * 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(void) +{ + char ch; + + buffer_get(&incoming_packet, &ch, 1); + return (u_char) ch; +} + +/* Returns an integer from the packet data. */ + +u_int +packet_get_int(void) +{ + 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) +{ + buffer_get_bignum(&incoming_packet, value); +} + +void +packet_get_bignum2(BIGNUM * value) +{ + buffer_get_bignum2(&incoming_packet, value); +} + +void * +packet_get_raw(u_int *length_ptr) +{ + u_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. + */ + +void * +packet_get_string(u_int *length_ptr) +{ + return buffer_get_string(&incoming_packet, length_ptr); +} +char * +packet_get_ascii_cstring() +{ + return buffer_get_ascii_cstring(&incoming_packet); +} +u_char * +packet_get_utf8_cstring() +{ + return buffer_get_utf8_cstring(&incoming_packet); +} + +/* + * 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), gettext(fmt), args); + va_end(args); + +#ifdef ALTPRIVSEP + /* shouldn't happen */ + if (packet_monitor) { + debug("packet_send_debug: %s", buf); + return; + } +#endif /* ALTPRIVSEP */ + + 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); + +#ifdef ALTPRIVSEP + /* + * If we packet_disconnect() in the monitor the fatal cleanups will take + * care of the child. See main() in sshd.c. We don't send the packet + * disconnect message here because: a) the child might not be looking + * for it and b) because we don't really know if the child is compat20 + * or not as we lost that information when packet_set_monitor() was + * called. + */ + if (packet_monitor) + goto close_stuff; +#endif /* ALTPRIVSEP */ + + /* 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_cstring(buf); + } + packet_send(); + packet_write_wait(); + +#ifdef ALTPRIVSEP +close_stuff: +#endif /* ALTPRIVSEP */ + /* Stop listening for connections. */ + channel_close_all(); + + /* 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(void) +{ + 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(void) +{ + fd_set *setp; + + setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * + sizeof(fd_mask)); + packet_write_poll(); + while (packet_have_data_to_write()) { + 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(void) +{ + 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(void) +{ + 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 + + 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, + &lowdelay, sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", + strerror(errno)); + } +#endif + set_nodelay(connection_in); + } +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + else if (packet_connection_is_ipv4()) { + /* + * Set IP options for a non-interactive connection. Use + * IPTOS_THROUGHPUT. + */ + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &throughput, + sizeof(throughput)) < 0) + error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); + } +#endif +} + +/* Returns true if the current connection is interactive. */ + +int +packet_is_interactive(void) +{ + 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; + } + called = 1; + debug("packet_set_maxsize: setting to %d", s); + max_packet_size = s; + return s; +} + +/* roundup current message to pad bytes */ +void +packet_add_padding(u_char pad) +{ + extra_pad = pad; +} + +/* + * 9.2. Ignored Data Message + * + * byte SSH_MSG_IGNORE + * string data + * + * All implementations MUST understand (and ignore) this message at any + * time (after receiving the protocol version). No implementation is + * required to send them. This message can be used as an additional + * protection measure against advanced traffic analysis techniques. + */ +void +packet_send_ignore(int nbytes) +{ + u_int32_t rand = 0; + int i; + +#ifdef ALTPRIVSEP + /* shouldn't happen -- see packet_set_monitor() */ + if (packet_monitor) + return; +#endif /* ALTPRIVSEP */ + + 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; + } +} + +#ifdef ALTPRIVSEP +void +packet_set_server(void) +{ + packet_server = 1; +} + +void +packet_set_no_monitor(void) +{ + packet_server = 0; +} + +int +packet_is_server(void) +{ + return (packet_server); +} + +void +packet_set_monitor(int pipe) +{ + int dup_fd; + + packet_server = 1; + packet_monitor = 1; + + /* + * Awful hack follows. + * + * For SSHv1 the monitor does not process any SSHv1 packets, only + * ALTPRIVSEP packets. We take advantage of that here to keep changes + * to packet.c to a minimum by using the SSHv2 binary packet protocol, + * with cipher "none," mac "none" and compression alg "none," as the + * basis for the monitor protocol. And so to force packet.c to treat + * packets as SSHv2 we force compat20 == 1 here. + * + * For completeness and to help future developers catch this we also + * force compat20 == 1 in the monitor loop, in serverloop.c. + */ + compat20 = 1; + + /* + * NOTE: Assumptions below! + * + * - lots of packet.c code assumes that (connection_in == + * connection_out) -> connection is socket + * + * - packet_close() does not shutdown() the connection fildes + * if connection_in != connection_out + * + * - other code assumes the connection is a socket if + * connection_in == connection_out + */ + + if ((dup_fd = dup(pipe)) < 0) + fatal("Monitor failed to start: %s", strerror(errno)); + + /* + * make sure that the monitor's child's socket is not shutdown(3SOCKET) + * when we packet_close() + */ + if (packet_connection_is_on_socket()) + connection_out = -1; + + /* now cleanup state related to ssh socket */ + packet_close(); + + /* now make the monitor pipe look like the ssh connection */ + packet_set_connection(pipe, dup_fd); +} + +int +packet_is_monitor(void) +{ + return (packet_monitor); +} +#endif /* ALTPRIVSEP */ |