diff options
author | green <green@FreeBSD.org> | 2001-05-04 03:57:05 +0000 |
---|---|---|
committer | green <green@FreeBSD.org> | 2001-05-04 03:57:05 +0000 |
commit | 8acd87ac472a182ef2d717212f2c0faba81143a5 (patch) | |
tree | 8070a266de2673f242df1ac3c19ad277bbd7e0f6 /crypto/openssh/packet.c | |
parent | 5bcde1229c897d3a1ecba9ae48d888c773877ad9 (diff) | |
download | FreeBSD-src-8acd87ac472a182ef2d717212f2c0faba81143a5.zip FreeBSD-src-8acd87ac472a182ef2d717212f2c0faba81143a5.tar.gz |
Say "hi" to the latest in the OpenSSH series, version 2.9!
Happy birthday to: rwatson
Diffstat (limited to 'crypto/openssh/packet.c')
-rw-r--r-- | crypto/openssh/packet.c | 401 |
1 files changed, 244 insertions, 157 deletions
diff --git a/crypto/openssh/packet.c b/crypto/openssh/packet.c index 3216fda..00109ea 100644 --- a/crypto/openssh/packet.c +++ b/crypto/openssh/packet.c @@ -37,13 +37,12 @@ */ #include "includes.h" -RCSID("$OpenBSD: packet.c,v 1.38 2000/10/12 14:21:12 markus Exp $"); +RCSID("$OpenBSD: packet.c,v 1.61 2001/04/05 10:42:51 markus Exp $"); #include "xmalloc.h" #include "buffer.h" #include "packet.h" #include "bufaux.h" -#include "ssh.h" #include "crc32.h" #include "getput.h" @@ -52,15 +51,14 @@ RCSID("$OpenBSD: packet.c,v 1.38 2000/10/12 14:21:12 markus Exp $"); #include "channels.h" #include "compat.h" +#include "ssh1.h" #include "ssh2.h" -#include <openssl/bn.h> -#include <openssl/dh.h> -#include <openssl/hmac.h> -#include "buffer.h" #include "cipher.h" #include "kex.h" -#include "hmac.h" +#include "mac.h" +#include "log.h" +#include "canohost.h" #ifdef PACKET_DEBUG #define DBG(x) x @@ -84,7 +82,7 @@ static int connection_out = -1; static int cipher_type = SSH_CIPHER_NONE; /* Protocol flags for the remote side. */ -static unsigned int remote_protocol_flags = 0; +static u_int remote_protocol_flags = 0; /* Encryption context for receiving data. This is only used for decryption. */ static CipherContext receive_context; @@ -106,6 +104,7 @@ 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; @@ -123,35 +122,14 @@ static int interactive_mode = 0; int use_ssh2_packet_format = 0; /* Session key information for Encryption and MAC */ -Kex *kex = NULL; +Newkeys *newkeys[MODE_MAX]; 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; + newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; } /* @@ -167,8 +145,8 @@ packet_set_connection(int fd_in, int fd_out) connection_in = fd_in; connection_out = fd_out; cipher_type = SSH_CIPHER_NONE; - cipher_init(&send_context, none, (unsigned char *) "", 0, NULL, 0); - cipher_init(&receive_context, none, (unsigned char *) "", 0, NULL, 0); + 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); @@ -272,7 +250,7 @@ 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(); } @@ -281,7 +259,7 @@ packet_close() /* Sets remote side protocol flags. */ void -packet_set_protocol_flags(unsigned int protocol_flags) +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); @@ -289,7 +267,7 @@ packet_set_protocol_flags(unsigned int protocol_flags) /* Returns the remote protocol flags set earlier by the above function. */ -unsigned int +u_int packet_get_protocol_flags() { return remote_protocol_flags; @@ -300,15 +278,24 @@ packet_get_protocol_flags() * Level is compression level 1 (fastest) - 9 (slow, best) as in gzip. */ -/*** XXXXX todo: kex means re-init */ +void +packet_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) + if (packet_compression && !use_ssh2_packet_format) fatal("Compression already enabled."); packet_compression = 1; - buffer_init(&compression_buffer); - buffer_compress_init(level); + packet_init_compression(); + buffer_compress_init_send(level); + buffer_compress_init_recv(); } /* @@ -318,7 +305,7 @@ packet_start_compression(int level) void packet_encrypt(CipherContext * cc, void *dest, void *src, - unsigned int bytes) + u_int bytes) { cipher_encrypt(cc, dest, src, bytes); } @@ -329,7 +316,7 @@ packet_encrypt(CipherContext * cc, void *dest, void *src, */ void -packet_decrypt(CipherContext *context, void *dest, void *src, unsigned int bytes) +packet_decrypt(CipherContext *context, void *dest, void *src, u_int bytes) { /* * Cryptographic attack detector for ssh - Modifications for packet.c @@ -350,7 +337,7 @@ packet_decrypt(CipherContext *context, void *dest, void *src, unsigned int bytes */ void -packet_set_encryption_key(const unsigned char *key, unsigned int keylen, +packet_set_encryption_key(const u_char *key, u_int keylen, int number) { Cipher *cipher = cipher_by_number(number); @@ -391,7 +378,7 @@ packet_start2(int type) void packet_start(int type) { - DBG(debug("packet_start[%d]",type)); + DBG(debug("packet_start[%d]", type)); if (use_ssh2_packet_format) packet_start2(type); else @@ -410,7 +397,7 @@ packet_put_char(int value) /* Appends an integer to the packet data. */ void -packet_put_int(unsigned int value) +packet_put_int(u_int value) { buffer_put_int(&outgoing_packet, value); } @@ -418,7 +405,7 @@ packet_put_int(unsigned int value) /* Appends a string to packet data. */ void -packet_put_string(const char *buf, unsigned int len) +packet_put_string(const char *buf, u_int len) { buffer_put_string(&outgoing_packet, buf, len); } @@ -429,7 +416,7 @@ packet_put_cstring(const char *str) } void -packet_put_raw(const char *buf, unsigned int len) +packet_put_raw(const char *buf, u_int len) { buffer_append(&outgoing_packet, buf, len); } @@ -454,11 +441,11 @@ packet_put_bignum2(BIGNUM * value) */ void -packet_send1() +packet_send1(void) { char buf[8], *cp; int i, padding, len; - unsigned int checksum; + u_int checksum; u_int32_t rand = 0; /* @@ -493,7 +480,7 @@ packet_send1() buffer_consume(&outgoing_packet, 8 - padding); /* Add check bytes. */ - checksum = ssh_crc32((unsigned char *) buffer_ptr(&outgoing_packet), + checksum = ssh_crc32((u_char *) buffer_ptr(&outgoing_packet), buffer_len(&outgoing_packet)); PUT_32BIT(buf, checksum); buffer_append(&outgoing_packet, buf, 4); @@ -524,28 +511,78 @@ packet_send1() */ } +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() +packet_send2(void) { - unsigned char *macbuf = NULL; + static u_int32_t seqnr = 0; + u_char *macbuf = NULL; char *cp; - unsigned int packet_length = 0; - unsigned int i, padlen, len; + u_int packet_length = 0; + u_int i, padlen, len; u_int32_t rand = 0; - static unsigned int seqnr = 0; int type; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; int block_size; - if (kex != NULL) { - enc = &kex->enc[MODE_OUT]; - mac = &kex->mac[MODE_OUT]; - comp = &kex->comp[MODE_OUT]; + 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; @@ -588,7 +625,7 @@ packet_send2() if (i % 4 == 0) rand = arc4random(); cp[i] = rand & 0xff; - rand <<= 8; + rand >>= 8; } } else { /* clear padding */ @@ -603,11 +640,9 @@ packet_send2() /* compute MAC over seqnr and packet(length fields, payload, padding) */ if (mac && mac->enabled) { - macbuf = hmac( mac->md, seqnr, - (unsigned char *) buffer_ptr(&outgoing_packet), - buffer_len(&outgoing_packet), - mac->key, mac->key_len - ); + 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. */ @@ -626,22 +661,8 @@ packet_send2() 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 @@ -664,10 +685,13 @@ int packet_read(int *payload_len_ptr) { 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(); @@ -682,17 +706,22 @@ packet_read(int *payload_len_ptr) || 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) + 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. */ - select(connection_in + 1, &set, NULL, NULL, NULL); + 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)); @@ -742,16 +771,16 @@ packet_read_expect(int *payload_len_ptr, int expected_type) int packet_read_poll1(int *payload_len_ptr) { - unsigned int len, padded_len; - unsigned char *ucp; + u_int len, padded_len; + u_char *ucp; char buf[8], *cp; - unsigned int checksum, stored_checksum; + 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 = (unsigned char *) buffer_ptr(&input); + 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); @@ -778,7 +807,7 @@ packet_read_poll1(int *payload_len_ptr) #endif /* Compute packet checksum. */ - checksum = ssh_crc32((unsigned char *) buffer_ptr(&incoming_packet), + checksum = ssh_crc32((u_char *) buffer_ptr(&incoming_packet), buffer_len(&incoming_packet) - 4); /* Skip padding. */ @@ -790,7 +819,7 @@ packet_read_poll1(int *payload_len_ptr) packet_disconnect("packet_read_poll: len %d != buffer_len %d.", len, buffer_len(&incoming_packet)); - ucp = (unsigned char *) buffer_ptr(&incoming_packet) + len - 4; + 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."); @@ -811,28 +840,28 @@ packet_read_poll1(int *payload_len_ptr) *payload_len_ptr = buffer_len(&incoming_packet); /* Return type. */ - return (unsigned char) buf[0]; + return (u_char) buf[0]; } int packet_read_poll2(int *payload_len_ptr) { - unsigned int padlen, need; - unsigned char buf[8], *macbuf; - unsigned char *ucp; + 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; - static unsigned int packet_length = 0; - static unsigned int seqnr = 0; int type; int maclen, block_size; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; - if (kex != NULL) { - enc = &kex->enc[MODE_IN]; - mac = &kex->mac[MODE_IN]; - comp = &kex->comp[MODE_IN]; + 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; @@ -848,7 +877,7 @@ packet_read_poll2(int *payload_len_ptr) buffer_append_space(&incoming_packet, &cp, block_size); packet_decrypt(&receive_context, cp, buffer_ptr(&input), block_size); - ucp = (unsigned char *) buffer_ptr(&incoming_packet); + 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); @@ -882,11 +911,9 @@ packet_read_poll2(int *payload_len_ptr) * increment sequence number for incoming packet */ if (mac && mac->enabled) { - macbuf = hmac( mac->md, seqnr, - (unsigned char *) buffer_ptr(&incoming_packet), - buffer_len(&incoming_packet), - mac->key, mac->key_len - ); + 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)); @@ -926,30 +953,16 @@ packet_read_poll2(int *payload_len_ptr) packet_length = 0; /* extract packet type */ - type = (unsigned char)buf[0]; - - if (type == SSH2_MSG_NEWKEYS) { - if (kex==NULL || mac==NULL || enc==NULL || comp==NULL) - fatal("packet_read_poll2: no KEX"); - if (mac->md != NULL) - mac->enabled = 1; - DBG(debug("cipher_init receive_context")); - cipher_init(&receive_context, enc->cipher, - enc->key, enc->cipher->key_len, - enc->iv, enc->cipher->block_size); - clear_enc_keys(enc, kex->we_need); - if (comp->type != 0 && comp->enabled == 0) { - comp->enabled = 1; - if (! packet_compression) - packet_start_compression(6); - } - } + 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); + fprintf(stderr, "read/plain[%d]:\r\n", type); buffer_dump(&incoming_packet); #endif - return (unsigned char)type; + return (u_char)type; } int @@ -979,14 +992,15 @@ packet_read_poll(int *payload_len_ptr) case SSH2_MSG_DISCONNECT: reason = packet_get_int(); msg = packet_get_string(NULL); - log("Received disconnect: %d: %.900s", reason, msg); + 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: @@ -998,7 +1012,8 @@ packet_read_poll(int *payload_len_ptr) break; case SSH_MSG_DISCONNECT: msg = packet_get_string(NULL); - log("Received disconnect: %.900s", msg); + log("Received disconnect from %s: %.400s", get_remote_ipaddr(), + msg); fatal_cleanup(); xfree(msg); break; @@ -1007,7 +1022,7 @@ packet_read_poll(int *payload_len_ptr) DBG(debug("received packet type %d", type)); return type; break; - } + } } } } @@ -1018,24 +1033,24 @@ packet_read_poll(int *payload_len_ptr) */ void -packet_process_incoming(const char *buf, unsigned int len) +packet_process_incoming(const char *buf, u_int len) { buffer_append(&input, buf, len); } /* Returns a character from the packet. */ -unsigned int +u_int packet_get_char() { char ch; buffer_get(&incoming_packet, &ch, 1); - return (unsigned char) ch; + return (u_char) ch; } /* Returns an integer from the packet data. */ -unsigned int +u_int packet_get_int() { return buffer_get_int(&incoming_packet); @@ -1081,7 +1096,7 @@ packet_remaining(void) */ char * -packet_get_string(unsigned int *length_ptr) +packet_get_string(u_int *length_ptr) { return buffer_get_string(&incoming_packet, length_ptr); } @@ -1101,6 +1116,9 @@ 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); @@ -1193,14 +1211,21 @@ packet_write_poll() 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()) { - fd_set set; - FD_ZERO(&set); - FD_SET(connection_out, &set); - select(connection_out + 1, NULL, &set, NULL, NULL); + 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. */ @@ -1225,45 +1250,45 @@ packet_not_very_much_data_to_write() /* Informs that the current session is interactive. Sets IP flags for that. */ void -packet_set_interactive(int interactive, int keepalives) +packet_set_interactive(int interactive) { + static int called = 0; + int lowdelay = IPTOS_LOWDELAY; + int throughput = IPTOS_THROUGHPUT; 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; - if (keepalives) { - /* Set keepalives if requested. */ - if (setsockopt(connection_in, SOL_SOCKET, SO_KEEPALIVE, (void *) &on, - sizeof(on)) < 0) - error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); - } /* - * IPTOS_LOWDELAY, TCP_NODELAY and IPTOS_THROUGHPUT are IPv4 only + * IPTOS_LOWDELAY and IPTOS_THROUGHPUT are IPv4 only */ - if (!packet_connection_is_ipv4()) - return; if (interactive) { /* * Set IP options for an interactive connection. Use * IPTOS_LOWDELAY and TCP_NODELAY. */ - int lowdelay = IPTOS_LOWDELAY; - if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &lowdelay, - sizeof(lowdelay)) < 0) - error("setsockopt IPTOS_LOWDELAY: %.100s", strerror(errno)); + if (packet_connection_is_ipv4()) { + if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, + (void *) &lowdelay, sizeof(lowdelay)) < 0) + error("setsockopt IPTOS_LOWDELAY: %.100s", + strerror(errno)); + } if (setsockopt(connection_in, IPPROTO_TCP, TCP_NODELAY, (void *) &on, sizeof(on)) < 0) error("setsockopt TCP_NODELAY: %.100s", strerror(errno)); - } else { + } else if (packet_connection_is_ipv4()) { /* * Set IP options for a non-interactive connection. Use * IPTOS_THROUGHPUT. */ - int throughput = IPTOS_THROUGHPUT; if (setsockopt(connection_in, IPPROTO_IP, IP_TOS, (void *) &throughput, sizeof(throughput)) < 0) error("setsockopt IPTOS_THROUGHPUT: %.100s", strerror(errno)); @@ -1295,3 +1320,65 @@ packet_set_maxsize(int 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; + } +} |