X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/64e0e67e3486760eb7a1432b3853804137e68840..fe661d8f9f98e269ff5efb3a79918ed25cbe6ee7:/packet.c diff --git a/packet.c b/packet.c index 5213e43e..0a8baa5b 100644 --- a/packet.c +++ b/packet.c @@ -13,7 +13,7 @@ * * * SSH2 packet format added by Markus Friedl. - * Copyright (c) 2000 Markus Friedl. All rights reserved. + * 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 @@ -37,7 +37,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: packet.c,v 1.51 2001/02/12 22:56:09 deraadt Exp $"); +RCSID("$OpenBSD: packet.c,v 1.100 2002/11/21 22:45:31 markus Exp $"); #include "xmalloc.h" #include "buffer.h" @@ -59,6 +59,8 @@ RCSID("$OpenBSD: packet.c,v 1.51 2001/02/12 22:56:09 deraadt Exp $"); #include "mac.h" #include "log.h" #include "canohost.h" +#include "misc.h" +#include "ssh.h" #ifdef PACKET_DEBUG #define DBG(x) x @@ -75,12 +77,6 @@ RCSID("$OpenBSD: packet.c,v 1.51 2001/02/12 22:56:09 deraadt Exp $"); 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; @@ -91,10 +87,10 @@ static CipherContext receive_context; static CipherContext send_context; /* Buffer for raw input data from the socket. */ -static Buffer input; +Buffer input; /* Buffer for raw output data going to the socket. */ -static Buffer output; +Buffer output; /* Buffer for the partial outgoing packet being constructed. */ static Buffer outgoing_packet; @@ -104,6 +100,7 @@ static Buffer incoming_packet; /* Scratch buffer for packet compression/decompression. */ static Buffer compression_buffer; +static int compression_buffer_ready = 0; /* Flag indicating whether packet compression/decompression is enabled. */ static int packet_compression = 0; @@ -117,40 +114,17 @@ static int initialized = 0; /* Set to true if the connection is interactive. */ static int interactive_mode = 0; -/* True if SSH2 packet format is used */ -int use_ssh2_packet_format = 0; - /* Session key information for Encryption and MAC */ -Kex *kex = NULL; +Newkeys *newkeys[MODE_MAX]; +static u_int32_t read_seqnr = 0; +static u_int32_t send_seqnr = 0; -void -packet_set_kex(Kex *k) -{ - if( k->mac[MODE_IN ].key == NULL || - k->enc[MODE_IN ].key == NULL || - k->enc[MODE_IN ].iv == NULL || - k->mac[MODE_OUT].key == NULL || - k->enc[MODE_OUT].key == NULL || - k->enc[MODE_OUT].iv == NULL) - fatal("bad KEX"); - kex = k; -} -void -clear_enc_keys(Enc *enc, int len) -{ - memset(enc->iv, 0, len); - memset(enc->key, 0, len); - xfree(enc->iv); - xfree(enc->key); - enc->iv = NULL; - enc->key = NULL; -} -void -packet_set_ssh2_format(void) -{ - DBG(debug("use_ssh2_packet_format")); - use_ssh2_packet_format = 1; -} +/* 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 @@ -160,13 +134,14 @@ 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); + cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT); + cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); + newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; if (!initialized) { initialized = 1; buffer_init(&input); @@ -181,7 +156,7 @@ packet_set_connection(int fd_in, int fd_out) /* Returns 1 if remote host is connected via socket, 0 if not. */ int -packet_connection_is_on_socket() +packet_connection_is_on_socket(void) { struct sockaddr_storage from, to; socklen_t fromlen, tolen; @@ -204,10 +179,103 @@ packet_connection_is_on_socket() 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() +packet_connection_is_ipv4(void) { struct sockaddr_storage to; socklen_t tolen = sizeof(to); @@ -215,15 +283,20 @@ packet_connection_is_ipv4() 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; + 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() +packet_set_nonblocking(void) { /* Set the socket into non-blocking mode. */ if (fcntl(connection_in, F_SETFL, O_NONBLOCK) < 0) @@ -238,7 +311,7 @@ packet_set_nonblocking() /* Returns the socket used for reading. */ int -packet_get_connection_in() +packet_get_connection_in(void) { return connection_in; } @@ -246,7 +319,7 @@ packet_get_connection_in() /* Returns the descriptor used for writing. */ int -packet_get_connection_out() +packet_get_connection_out(void) { return connection_out; } @@ -254,7 +327,7 @@ packet_get_connection_out() /* Closes the connection and clears and frees internal data structures. */ void -packet_close() +packet_close(void) { if (!initialized) return; @@ -270,10 +343,12 @@ packet_close() buffer_free(&output); buffer_free(&outgoing_packet); buffer_free(&incoming_packet); - if (packet_compression) { + if (compression_buffer_ready) { buffer_free(&compression_buffer); buffer_compress_uninit(); } + cipher_cleanup(&send_context); + cipher_cleanup(&receive_context); } /* Sets remote side protocol flags. */ @@ -282,13 +357,12 @@ 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() +packet_get_protocol_flags(void) { return remote_protocol_flags; } @@ -298,47 +372,24 @@ packet_get_protocol_flags() * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ -/*** XXXXX todo: kex means re-init */ -void -packet_start_compression(int level) +static void +packet_init_compression(void) { - if (packet_compression) - fatal("Compression already enabled."); - packet_compression = 1; + if (compression_buffer_ready == 1) + return; + compression_buffer_ready = 1; buffer_init(&compression_buffer); - buffer_compress_init(level); -} - -/* - * Encrypts the given number of bytes, copying from src to dest. bytes is - * known to be a multiple of 8. - */ - -void -packet_encrypt(CipherContext * cc, void *dest, void *src, - 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) +packet_start_compression(int level) { - /* - * 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); + if (packet_compression && !compat20) + fatal("Compression already enabled."); + packet_compression = 1; + packet_init_compression(); + buffer_compress_init_send(level); + buffer_compress_init_recv(); } /* @@ -352,89 +403,71 @@ 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); + 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); } -/* Starts constructing a packet to send. */ - -void -packet_start1(int type) +u_int +packet_get_encryption_key(u_char *key) { - char buf[9]; - - buffer_clear(&outgoing_packet); - memset(buf, 0, 8); - buf[8] = type; - buffer_append(&outgoing_packet, buf, 9); + if (key == NULL) + return (ssh1_keylen); + memcpy(key, ssh1_key, ssh1_keylen); + return (ssh1_keylen); } +/* Start constructing a packet to send. */ void -packet_start2(int type) +packet_start(u_char type) { - char buf[4+1+1]; + u_char buf[9]; + int len; + DBG(debug("packet_start[%d]", type)); + len = compat20 ? 6 : 9; + memset(buf, 0, len - 1); + buf[len - 1] = type; buffer_clear(&outgoing_packet); - memset(buf, 0, 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); + buffer_append(&outgoing_packet, buf, len); } -/* Appends a character to the packet data. */ - +/* Append payload. */ void packet_put_char(int value) { char ch = value; + buffer_append(&outgoing_packet, &ch, 1); } - -/* Appends an integer to the packet data. */ - void packet_put_int(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) +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_string(&outgoing_packet, str, strlen(str)); + buffer_put_cstring(&outgoing_packet, str); } - void -packet_put_raw(const char *buf, u_int len) +packet_put_raw(const void *buf, u_int len) { buffer_append(&outgoing_packet, buf, len); } - - -/* Appends an arbitrary precision integer to packet data. */ - void packet_put_bignum(BIGNUM * value) { @@ -451,10 +484,10 @@ packet_put_bignum2(BIGNUM * value) * encrypts the packet before sending. */ -void +static void packet_send1(void) { - char buf[8], *cp; + u_char buf[8], *cp; int i, padding, len; u_int checksum; u_int32_t rand = 0; @@ -472,14 +505,14 @@ packet_send1(void) buffer_compress(&outgoing_packet, &compression_buffer); buffer_clear(&outgoing_packet); buffer_append(&outgoing_packet, buffer_ptr(&compression_buffer), - buffer_len(&compression_buffer)); + buffer_len(&compression_buffer)); } /* Compute packet length without padding (add checksum, remove padding). */ len = buffer_len(&outgoing_packet) + 4 - 8; /* Insert padding. Initialized to zero in packet_start1() */ padding = 8 - len % 8; - if (cipher_type != SSH_CIPHER_NONE) { + if (!send_context.plaintext) { cp = buffer_ptr(&outgoing_packet); for (i = 0; i < padding; i++) { if (i % 4 == 0) @@ -491,7 +524,7 @@ packet_send1(void) buffer_consume(&outgoing_packet, 8 - padding); /* Add check bytes. */ - checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet), + checksum = ssh_crc32(buffer_ptr(&outgoing_packet), buffer_len(&outgoing_packet)); PUT_32BIT(buf, checksum); buffer_append(&outgoing_packet, buf, 4); @@ -504,9 +537,9 @@ packet_send1(void) /* Append to output. */ PUT_32BIT(buf, len); buffer_append(&output, buf, 4); - buffer_append_space(&output, &cp, buffer_len(&outgoing_packet)); - packet_encrypt(&send_context, cp, buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet)); + cp = buffer_append_space(&output, buffer_len(&outgoing_packet)); + cipher_crypt(&send_context, cp, buffer_ptr(&outgoing_packet), + buffer_len(&outgoing_packet)); #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); @@ -522,33 +555,88 @@ packet_send1(void) */ } +void +set_newkeys(int mode) +{ + Enc *enc; + Mac *mac; + Comp *comp; + CipherContext *cc; + int encrypt; + + debug2("set_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("set_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) */ -void +static void packet_send2(void) { - static u_int32_t seqnr = 0; - u_char *macbuf = NULL; - char *cp; + u_char type, *cp, *macbuf = NULL; + u_char padlen, pad; u_int packet_length = 0; - u_int i, padlen, len; + u_int i, len; u_int32_t rand = 0; - int type; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; int block_size; - if (kex != NULL) { - enc = &kex->enc[MODE_OUT]; - mac = &kex->mac[MODE_OUT]; - comp = &kex->comp[MODE_OUT]; + 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; + block_size = enc ? enc->block_size : 8; cp = buffer_ptr(&outgoing_packet); - type = cp[5] & 0xff; + type = cp[5]; #ifdef PACKET_DEBUG fprintf(stderr, "plain: "); @@ -579,14 +667,23 @@ packet_send2(void) 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) { + 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; + rand >>= 8; } } else { /* clear padding */ @@ -596,19 +693,19 @@ packet_send2(void) packet_length = buffer_len(&outgoing_packet) - 4; cp = buffer_ptr(&outgoing_packet); PUT_32BIT(cp, packet_length); - cp[4] = padlen & 0xff; + cp[4] = padlen; DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); /* compute MAC over seqnr and packet(length fields, payload, padding) */ if (mac && mac->enabled) { - macbuf = mac_compute(mac, seqnr, - (u_char *) buffer_ptr(&outgoing_packet), + macbuf = mac_compute(mac, send_seqnr, + buffer_ptr(&outgoing_packet), buffer_len(&outgoing_packet)); - DBG(debug("done calc MAC out #%d", seqnr)); + DBG(debug("done calc MAC out #%d", send_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), + 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) @@ -618,32 +715,18 @@ packet_send2(void) buffer_dump(&output); #endif /* increment sequence number for outgoing packets */ - if (++seqnr == 0) + if (++send_seqnr == 0) log("outgoing seqnr wraps around"); buffer_clear(&outgoing_packet); - if (type == SSH2_MSG_NEWKEYS) { - if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) - fatal("packet_send2: no KEX"); - if (mac->md != NULL) - mac->enabled = 1; - DBG(debug("cipher_init send_context")); - cipher_init(&send_context, enc->cipher, - enc->key, enc->cipher->key_len, - enc->iv, enc->cipher->block_size); - clear_enc_keys(enc, kex->we_need); - if (comp->type != 0 && comp->enabled == 0) { - comp->enabled = 1; - if (! packet_compression) - packet_start_compression(6); - } - } + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_OUT); } void -packet_send() +packet_send(void) { - if (use_ssh2_packet_format) + if (compat20) packet_send2(); else packet_send1(); @@ -657,38 +740,44 @@ packet_send() */ int -packet_read(int *payload_len_ptr) +packet_read_seqnr(u_int32_t *seqnr_p) { int type, len; - fd_set set; + fd_set *setp; char buf[8192]; DBG(debug("packet_read()")); + setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * + sizeof(fd_mask)); + /* Since we are blocking, ensure that all written packets have been sent. */ packet_write_wait(); /* 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 = packet_read_poll_seqnr(seqnr_p); + if (!compat20 && ( type == SSH_SMSG_SUCCESS || type == SSH_SMSG_FAILURE || type == SSH_CMSG_EOF || type == SSH_CMSG_EXIT_CONFIRMATION)) - packet_integrity_check(*payload_len_ptr, 0, type); + packet_check_eom(); /* If we got a packet, return it. */ - if (type != SSH_MSG_NONE) + if (type != SSH_MSG_NONE) { + xfree(setp); return type; + } /* * Otherwise, wait for some data to arrive, add it to the * buffer, and try again. */ - FD_ZERO(&set); - FD_SET(connection_in, &set); + memset(setp, 0, howmany(connection_in + 1, NFDBITS) * + sizeof(fd_mask)); + FD_SET(connection_in, setp); /* Wait for some data to arrive. */ - while (select(connection_in + 1, &set, NULL, NULL, NULL) == -1 && + while (select(connection_in + 1, setp, NULL, NULL, NULL) == -1 && (errno == EAGAIN || errno == EINTR)) ; @@ -706,17 +795,23 @@ packet_read(int *payload_len_ptr) /* NOTREACHED */ } +int +packet_read(void) +{ + return packet_read_seqnr(NULL); +} + /* * Waits until a packet has been received, verifies that its type matches * that given, and gives a fatal error and exits if there is a mismatch. */ void -packet_read_expect(int *payload_len_ptr, int expected_type) +packet_read_expect(int expected_type) { int type; - type = packet_read(payload_len_ptr); + type = packet_read(); if (type != expected_type) packet_disconnect("Protocol error: expected packet type %d, got %d", expected_type, type); @@ -729,30 +824,23 @@ packet_read_expect(int *payload_len_ptr, int expected_type) * SSH_MSG_DISCONNECT is handled specially here. Also, * SSH_MSG_IGNORE messages are skipped by this function and are never returned * to higher levels. - * - * The returned payload_len does include space consumed by: - * Packet length - * Padding - * Packet type - * Check bytes */ -int -packet_read_poll1(int *payload_len_ptr) +static int +packet_read_poll1(void) { u_int len, padded_len; - u_char *ucp; - char buf[8], *cp; + u_char *cp, type; u_int checksum, stored_checksum; /* Check if input size is less than minimum packet size. */ if (buffer_len(&input) < 4 + 8) return SSH_MSG_NONE; /* Get length of incoming packet. */ - ucp = (u_char *) buffer_ptr(&input); - len = GET_32BIT(ucp); + cp = buffer_ptr(&input); + len = GET_32BIT(cp); if (len < 1 + 2 + 2 || len > 256 * 1024) - packet_disconnect("Bad packet length %d.", len); + packet_disconnect("Bad packet length %u.", len); padded_len = (len + 8) & ~7; /* Check if the packet has been entirely received. */ @@ -764,10 +852,20 @@ packet_read_poll1(int *payload_len_ptr) /* Consume packet length. */ buffer_consume(&input, 4); - /* Copy data to incoming_packet. */ + /* + * Cryptographic attack detector for ssh + * (C)1998 CORE-SDI, Buenos Aires Argentina + * Ariel Futoransky(futo@core-sdi.com) + */ + if (!receive_context.plaintext && + detect_attack(buffer_ptr(&input), padded_len, NULL) == DEATTACK_DETECTED) + packet_disconnect("crc32 compensation attack: network attack detected"); + + /* Decrypt data to incoming_packet. */ buffer_clear(&incoming_packet); - buffer_append_space(&incoming_packet, &cp, padded_len); - packet_decrypt(&receive_context, cp, buffer_ptr(&input), padded_len); + cp = buffer_append_space(&incoming_packet, padded_len); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), padded_len); + buffer_consume(&input, padded_len); #ifdef PACKET_DEBUG @@ -776,25 +874,23 @@ packet_read_poll1(int *payload_len_ptr) #endif /* Compute packet checksum. */ - checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet), + checksum = ssh_crc32(buffer_ptr(&incoming_packet), buffer_len(&incoming_packet) - 4); /* Skip padding. */ buffer_consume(&incoming_packet, 8 - len % 8); /* Test check bytes. */ - if (len != buffer_len(&incoming_packet)) - packet_disconnect("packet_read_poll: len %d != buffer_len %d.", + packet_disconnect("packet_read_poll1: len %d != buffer_len %d.", len, buffer_len(&incoming_packet)); - ucp = (u_char *) buffer_ptr(&incoming_packet) + len - 4; - stored_checksum = GET_32BIT(ucp); + cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; + stored_checksum = GET_32BIT(cp); if (checksum != stored_checksum) packet_disconnect("Corrupted check bytes on input."); buffer_consume_end(&incoming_packet, 4); - /* If using packet compression, decompress the packet. */ if (packet_compression) { buffer_clear(&compression_buffer); buffer_uncompress(&incoming_packet, &compression_buffer); @@ -802,38 +898,28 @@ packet_read_poll1(int *payload_len_ptr) 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]; + type = buffer_get_char(&incoming_packet); + return type; } -int -packet_read_poll2(int *payload_len_ptr) +static int +packet_read_poll2(u_int32_t *seqnr_p) { - static u_int32_t seqnr = 0; static u_int packet_length = 0; u_int padlen, need; - u_char buf[8], *macbuf; - u_char *ucp; - char *cp; - int type; + u_char *macbuf, *cp, type; int maclen, block_size; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; - if (kex != NULL) { - enc = &kex->enc[MODE_IN]; - mac = &kex->mac[MODE_IN]; - comp = &kex->comp[MODE_IN]; + 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; + block_size = enc ? enc->block_size : 8; if (packet_length == 0) { /* @@ -843,16 +929,16 @@ packet_read_poll2(int *payload_len_ptr) 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), + cp = buffer_append_space(&incoming_packet, block_size); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), block_size); - ucp = (u_char *) buffer_ptr(&incoming_packet); - packet_length = GET_32BIT(ucp); + 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); + packet_disconnect("Bad packet length %u.", packet_length); } - DBG(debug("input: packet len %d", packet_length+4)); + DBG(debug("input: packet len %u", packet_length+4)); buffer_consume(&input, block_size); } /* we have a partial packet of block_size bytes */ @@ -872,28 +958,30 @@ packet_read_poll2(int *payload_len_ptr) 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); + cp = buffer_append_space(&incoming_packet, need); + cipher_crypt(&receive_context, cp, buffer_ptr(&input), need); buffer_consume(&input, need); /* * compute MAC over seqnr and packet, * increment sequence number for incoming packet */ if (mac && mac->enabled) { - macbuf = mac_compute(mac, seqnr, - (u_char *) buffer_ptr(&incoming_packet), + 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", seqnr)); + DBG(debug("MAC #%d ok", read_seqnr)); buffer_consume(&input, mac->mac_len); } - if (++seqnr == 0) + if (seqnr_p != NULL) + *seqnr_p = read_seqnr; + if (++read_seqnr == 0) log("incoming seqnr wraps around"); /* get padlen */ - cp = buffer_ptr(&incoming_packet) + 4; - padlen = *cp & 0xff; + 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); @@ -909,59 +997,38 @@ packet_read_poll2(int *payload_len_ptr) 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))); + 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) { - if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) - fatal("packet_read_poll2: no KEX"); - if (mac->md != NULL) - mac->enabled = 1; - DBG(debug("cipher_init receive_context")); - cipher_init(&receive_context, enc->cipher, - enc->key, enc->cipher->key_len, - enc->iv, enc->cipher->block_size); - clear_enc_keys(enc, kex->we_need); - if (comp->type != 0 && comp->enabled == 0) { - comp->enabled = 1; - if (! packet_compression) - packet_start_compression(6); - } - } - + type = buffer_get_char(&incoming_packet); + if (type == SSH2_MSG_NEWKEYS) + set_newkeys(MODE_IN); #ifdef PACKET_DEBUG - fprintf(stderr, "read/plain[%d]:\r\n",type); + fprintf(stderr, "read/plain[%d]:\r\n", type); buffer_dump(&incoming_packet); #endif - return (u_char)type; + /* reset for next packet */ + packet_length = 0; + return type; } int -packet_read_poll(int *payload_len_ptr) +packet_read_poll_seqnr(u_int32_t *seqnr_p) { + u_int reason, seqnr; + u_char type; 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) + for (;;) { + if (compat20) { + type = packet_read_poll2(seqnr_p); + if (type) DBG(debug("received packet type %d", type)); - switch(type) { + switch (type) { case SSH2_MSG_IGNORE: break; case SSH2_MSG_DEBUG: @@ -975,17 +1042,23 @@ packet_read_poll(int *payload_len_ptr) 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); + 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 { - switch(type) { + type = packet_read_poll1(); + switch (type) { case SSH_MSG_IGNORE: break; case SSH_MSG_DEBUG: @@ -995,13 +1068,13 @@ packet_read_poll(int *payload_len_ptr) break; case SSH_MSG_DISCONNECT: msg = packet_get_string(NULL); - log("Received disconnect from %s: %.400s", get_remote_ipaddr(), - msg); + log("Received disconnect from %s: %.400s", + get_remote_ipaddr(), msg); fatal_cleanup(); xfree(msg); break; default: - if (type != 0) + if (type) DBG(debug("received packet type %d", type)); return type; break; @@ -1010,6 +1083,12 @@ packet_read_poll(int *payload_len_ptr) } } +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. @@ -1024,9 +1103,10 @@ packet_process_incoming(const char *buf, u_int len) /* Returns a character from the packet. */ u_int -packet_get_char() +packet_get_char(void) { char ch; + buffer_get(&incoming_packet, &ch, 1); return (u_char) ch; } @@ -1034,7 +1114,7 @@ packet_get_char() /* Returns an integer from the packet data. */ u_int -packet_get_int() +packet_get_int(void) { return buffer_get_int(&incoming_packet); } @@ -1045,21 +1125,22 @@ packet_get_int() */ void -packet_get_bignum(BIGNUM * value, int *length_ptr) +packet_get_bignum(BIGNUM * value) { - *length_ptr = buffer_get_bignum(&incoming_packet, value); + buffer_get_bignum(&incoming_packet, value); } void -packet_get_bignum2(BIGNUM * value, int *length_ptr) +packet_get_bignum2(BIGNUM * value) { - *length_ptr = buffer_get_bignum2(&incoming_packet, value); + buffer_get_bignum2(&incoming_packet, value); } -char * +void * packet_get_raw(int *length_ptr) { int bytes = buffer_len(&incoming_packet); + if (length_ptr != NULL) *length_ptr = bytes; return buffer_ptr(&incoming_packet); @@ -1078,7 +1159,7 @@ packet_remaining(void) * integer into which the length of the string is stored. */ -char * +void * packet_get_string(u_int *length_ptr) { return buffer_get_string(&incoming_packet, length_ptr); @@ -1132,6 +1213,7 @@ 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; @@ -1144,6 +1226,9 @@ packet_disconnect(const char *fmt,...) vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); + /* Display the error locally */ + log("Disconnecting: %.100s", buf); + /* Send the disconnect message to the other side, and wait for it to get sent. */ if (compat20) { packet_start(SSH2_MSG_DISCONNECT); @@ -1152,28 +1237,27 @@ packet_disconnect(const char *fmt,...) packet_put_cstring(""); } else { packet_start(SSH_MSG_DISCONNECT); - packet_put_string(buf, strlen(buf)); + packet_put_cstring(buf); } packet_send(); packet_write_wait(); /* Stop listening for connections. */ - channel_stop_listening(); + channel_close_all(); /* Close the connection. */ packet_close(); - /* Display the error locally and exit. */ - log("Disconnecting: %.100s", buf); fatal_cleanup(); } /* Checks if there is any buffered output, and tries to write some of the output. */ void -packet_write_poll() +packet_write_poll(void) { int len = buffer_len(&output); + if (len > 0) { len = write(connection_out, buffer_ptr(&output), len); if (len <= 0) { @@ -1192,25 +1276,29 @@ packet_write_poll() */ void -packet_write_wait() +packet_write_wait(void) { + fd_set *setp; + + setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * + sizeof(fd_mask)); packet_write_poll(); while (packet_have_data_to_write()) { - fd_set set; - - FD_ZERO(&set); - FD_SET(connection_out, &set); - while (select(connection_out + 1, NULL, &set, NULL, NULL) == -1 && + memset(setp, 0, howmany(connection_out + 1, NFDBITS) * + sizeof(fd_mask)); + FD_SET(connection_out, setp); + while (select(connection_out + 1, NULL, setp, NULL, NULL) == -1 && (errno == EAGAIN || errno == EINTR)) ; packet_write_poll(); } + xfree(setp); } /* Returns true if there is buffered data to write to the connection. */ int -packet_have_data_to_write() +packet_have_data_to_write(void) { return buffer_len(&output) != 0; } @@ -1218,7 +1306,7 @@ packet_have_data_to_write() /* Returns true if there is not too much data to write to the connection. */ int -packet_not_very_much_data_to_write() +packet_not_very_much_data_to_write(void) { if (interactive_mode) return buffer_len(&output) < 16384; @@ -1236,7 +1324,6 @@ packet_set_interactive(int interactive) int lowdelay = IPTOS_LOWDELAY; int throughput = IPTOS_THROUGHPUT; #endif - int on = 1; if (called) return; @@ -1259,21 +1346,19 @@ packet_set_interactive(int interactive) #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) + &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)); + set_nodelay(connection_in); } 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, + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, &throughput, sizeof(throughput)) < 0) error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); #endif @@ -1283,7 +1368,7 @@ packet_set_interactive(int interactive) /* Returns true if the current connection is interactive. */ int -packet_is_interactive() +packet_is_interactive(void) { return interactive_mode; } @@ -1292,6 +1377,7 @@ 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); @@ -1301,7 +1387,42 @@ packet_set_maxsize(int s) log("packet_set_maxsize: bad size %d", s); return -1; } - log("packet_set_maxsize: setting to %d", s); + called = 1; + debug("packet_set_maxsize: setting to %d", s); max_packet_size = s; return s; } + +/* roundup current message to pad bytes */ +void +packet_add_padding(u_char pad) +{ + extra_pad = pad; +} + +/* + * 9.2. Ignored Data Message + * + * byte SSH_MSG_IGNORE + * string data + * + * All implementations MUST understand (and ignore) this message at any + * time (after receiving the protocol version). No implementation is + * required to send them. This message can be used as an additional + * protection measure against advanced traffic analysis techniques. + */ +void +packet_send_ignore(int nbytes) +{ + u_int32_t rand = 0; + int i; + + packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE); + packet_put_int(nbytes); + for (i = 0; i < nbytes; i++) { + if (i % 4 == 0) + rand = arc4random(); + packet_put_char(rand & 0xff); + rand >>= 8; + } +}