X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/ffd7b36ba59c788a8f61907d042a41531656233a..a29c98984d9bf762a6199a71c71a3d032abc7f28:/packet.c diff --git a/packet.c b/packet.c index 9887d25a..6d58ebc0 100644 --- a/packet.c +++ b/packet.c @@ -1,3 +1,4 @@ +/* $OpenBSD: packet.c,v 1.145 2006/09/19 21:14:08 markus Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland @@ -37,26 +38,39 @@ */ #include "includes.h" -RCSID("$OpenBSD: packet.c,v 1.105 2003/04/02 09:48:07 markus Exp $"); + +#include +#include "openbsd-compat/sys-queue.h" +#include +#include +#ifdef HAVE_SYS_TIME_H +# include +#endif + +#include +#include +#include -#include +#include +#include +#include +#include +#include +#include +#include #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 "key.h" #include "kex.h" #include "mac.h" #include "log.h" @@ -108,7 +122,7 @@ static int compression_buffer_ready = 0; static int packet_compression = 0; /* default maximum packet size */ -int max_packet_size = 32768; +u_int max_packet_size = 32768; /* Flag indicating whether this module has been initialized. */ static int initialized = 0; @@ -116,6 +130,12 @@ static int initialized = 0; /* Set to true if the connection is interactive. */ static int interactive_mode = 0; +/* Set to true if we are the server side. */ +static int server_side = 0; + +/* Set to true if we are authenticated. */ +static int after_authentication = 0; + /* Session key information for Encryption and MAC */ Newkeys *newkeys[MODE_MAX]; static struct packet_state { @@ -154,8 +174,10 @@ packet_set_connection(int fd_in, int fd_out) fatal("packet_set_connection: cannot load cipher 'none'"); connection_in = fd_in; connection_out = fd_out; - cipher_init(&send_context, none, "", 0, NULL, 0, CIPHER_ENCRYPT); - cipher_init(&receive_context, none, "", 0, NULL, 0, CIPHER_DECRYPT); + cipher_init(&send_context, none, (const u_char *)"", + 0, NULL, 0, CIPHER_ENCRYPT); + cipher_init(&receive_context, none, (const u_char *)"", + 0, NULL, 0, CIPHER_DECRYPT); newkeys[MODE_IN] = newkeys[MODE_OUT] = NULL; if (!initialized) { initialized = 1; @@ -165,8 +187,6 @@ packet_set_connection(int fd_in, int fd_out) buffer_init(&incoming_packet); TAILQ_INIT(&outgoing); } - /* 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. */ @@ -252,6 +272,7 @@ packet_get_keyiv_len(int mode) return (cipher_get_keyiv_len(cc)); } + void packet_set_iv(int mode, u_char *dat) { @@ -264,8 +285,9 @@ packet_set_iv(int mode, u_char *dat) cipher_set_keyiv(cc, dat); } + int -packet_get_ssh1_cipher() +packet_get_ssh1_cipher(void) { return (cipher_get_number(receive_context.cipher)); } @@ -306,7 +328,7 @@ packet_connection_is_ipv4(void) if (to.ss_family == AF_INET) return 1; #ifdef IPV4_IN_IPV6 - if (to.ss_family == AF_INET6 && + if (to.ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr)) return 1; #endif @@ -319,13 +341,10 @@ 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)); + set_nonblock(connection_in); - if (connection_out != connection_in) { - if (fcntl(connection_out, F_SETFL, O_NONBLOCK) < 0) - error("fcntl O_NONBLOCK: %.100s", strerror(errno)); - } + if (connection_out != connection_in) + set_nonblock(connection_out); } /* Returns the socket used for reading. */ @@ -468,31 +487,37 @@ packet_put_char(int 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_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) { @@ -510,7 +535,7 @@ packet_send1(void) u_char buf[8], *cp; int i, padding, len; u_int checksum; - u_int32_t rand = 0; + u_int32_t rnd = 0; /* * If using packet compression, compress the payload of the outgoing @@ -536,9 +561,9 @@ packet_send1(void) cp = buffer_ptr(&outgoing_packet); for (i = 0; i < padding; i++) { if (i % 4 == 0) - rand = arc4random(); - cp[7 - i] = rand & 0xff; - rand >>= 8; + rnd = arc4random(); + cp[7 - i] = rnd & 0xff; + rnd >>= 8; } } buffer_consume(&outgoing_packet, 8 - padding); @@ -546,7 +571,7 @@ packet_send1(void) /* Add check bytes. */ checksum = ssh_crc32(buffer_ptr(&outgoing_packet), buffer_len(&outgoing_packet)); - PUT_32BIT(buf, checksum); + put_u32(buf, checksum); buffer_append(&outgoing_packet, buf, 4); #ifdef PACKET_DEBUG @@ -555,7 +580,7 @@ packet_send1(void) #endif /* Append to output. */ - PUT_32BIT(buf, len); + put_u32(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), @@ -569,7 +594,7 @@ packet_send1(void) buffer_clear(&outgoing_packet); /* - * Note that the packet is now only buffered in output. It won\'t be + * 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. */ @@ -583,18 +608,18 @@ set_newkeys(int mode) Comp *comp; CipherContext *cc; u_int64_t *max_blocks; - int encrypt; + int crypt_type; debug2("set_newkeys: mode %d", mode); if (mode == MODE_OUT) { cc = &send_context; - encrypt = CIPHER_ENCRYPT; + crypt_type = CIPHER_ENCRYPT; p_send.packets = p_send.blocks = 0; max_blocks = &max_blocks_out; } else { cc = &receive_context; - encrypt = CIPHER_DECRYPT; + crypt_type = CIPHER_DECRYPT; p_read.packets = p_read.blocks = 0; max_blocks = &max_blocks_in; } @@ -623,11 +648,13 @@ set_newkeys(int mode) 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); + enc->iv, enc->block_size, crypt_type); /* 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) { + if ((comp->type == COMP_ZLIB || + (comp->type == COMP_DELAYED && after_authentication)) && + comp->enabled == 0) { packet_init_compression(); if (mode == MODE_OUT) buffer_compress_init_send(6); @@ -635,11 +662,50 @@ set_newkeys(int mode) buffer_compress_init_recv(); comp->enabled = 1; } - *max_blocks = ((u_int64_t)1 << (enc->block_size*2)); + /* + * The 2^(blocksize*2) limit is too expensive for 3DES, + * blowfish, etc, so enforce a 1GB limit for small blocksizes. + */ + if (enc->block_size >= 16) + *max_blocks = (u_int64_t)1 << (enc->block_size*2); + else + *max_blocks = ((u_int64_t)1 << 30) / enc->block_size; if (rekey_limit) *max_blocks = MIN(*max_blocks, rekey_limit / enc->block_size); } +/* + * Delayed compression for SSH2 is enabled after authentication: + * This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent, + * and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received. + */ +static void +packet_enable_delayed_compress(void) +{ + Comp *comp = NULL; + int mode; + + /* + * Remember that we are past the authentication step, so rekeying + * with COMP_DELAYED will turn on compression immediately. + */ + after_authentication = 1; + for (mode = 0; mode < MODE_MAX; mode++) { + /* protocol error: USERAUTH_SUCCESS received before NEWKEYS */ + if (newkeys[mode] == NULL) + continue; + comp = &newkeys[mode]->comp; + if (comp && !comp->enabled && comp->type == COMP_DELAYED) { + 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) */ @@ -650,7 +716,7 @@ packet_send2_wrapped(void) u_char padlen, pad; u_int packet_length = 0; u_int i, len; - u_int32_t rand = 0; + u_int32_t rnd = 0; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; @@ -709,9 +775,9 @@ packet_send2_wrapped(void) /* random padding */ for (i = 0; i < padlen; i++) { if (i % 4 == 0) - rand = arc4random(); - cp[i] = rand & 0xff; - rand >>= 8; + rnd = arc4random(); + cp[i] = rnd & 0xff; + rnd >>= 8; } } else { /* clear padding */ @@ -720,7 +786,7 @@ packet_send2_wrapped(void) /* 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); + put_u32(cp, packet_length); cp[4] = padlen; DBG(debug("send: len %d (includes padlen %d)", packet_length+4, padlen)); @@ -737,14 +803,14 @@ packet_send2_wrapped(void) buffer_len(&outgoing_packet)); /* append unencrypted MAC */ if (mac && mac->enabled) - buffer_append(&output, (char *)macbuf, mac->mac_len); + buffer_append(&output, macbuf, mac->mac_len); #ifdef PACKET_DEBUG fprintf(stderr, "encrypted: "); buffer_dump(&output); #endif /* increment sequence number for outgoing packets */ if (++p_send.seqnr == 0) - log("outgoing seqnr wraps around"); + logit("outgoing seqnr wraps around"); if (++p_send.packets == 0) if (!(datafellows & SSH_BUG_NOREKEY)) fatal("XXX too many packets with same key"); @@ -753,6 +819,8 @@ packet_send2_wrapped(void) if (type == SSH2_MSG_NEWKEYS) set_newkeys(MODE_OUT); + else if (type == SSH2_MSG_USERAUTH_SUCCESS && server_side) + packet_enable_delayed_compress(); } static void @@ -825,7 +893,7 @@ packet_read_seqnr(u_int32_t *seqnr_p) char buf[8192]; DBG(debug("packet_read()")); - setp = (fd_set *)xmalloc(howmany(connection_in+1, NFDBITS) * + setp = (fd_set *)xcalloc(howmany(connection_in+1, NFDBITS), sizeof(fd_mask)); /* Since we are blocking, ensure that all written packets have been sent. */ @@ -862,8 +930,8 @@ packet_read_seqnr(u_int32_t *seqnr_p) /* 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(); + logit("Connection closed by %.200s", get_remote_ipaddr()); + cleanup_exit(255); } if (len < 0) fatal("Read from socket failed: %.100s", strerror(errno)); @@ -916,7 +984,7 @@ packet_read_poll1(void) return SSH_MSG_NONE; /* Get length of incoming packet. */ cp = buffer_ptr(&input); - len = GET_32BIT(cp); + len = get_u32(cp); if (len < 1 + 2 + 2 || len > 256 * 1024) packet_disconnect("Bad packet length %u.", len); padded_len = (len + 8) & ~7; @@ -935,9 +1003,16 @@ packet_read_poll1(void) * (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"); + if (!receive_context.plaintext) { + switch (detect_attack(buffer_ptr(&input), padded_len)) { + case DEATTACK_DETECTED: + packet_disconnect("crc32 compensation attack: " + "network attack detected"); + case DEATTACK_DOS_DETECTED: + packet_disconnect("deattack denial of " + "service detected"); + } + } /* Decrypt data to incoming_packet. */ buffer_clear(&incoming_packet); @@ -964,7 +1039,7 @@ packet_read_poll1(void) len, buffer_len(&incoming_packet)); cp = (u_char *)buffer_ptr(&incoming_packet) + len - 4; - stored_checksum = GET_32BIT(cp); + stored_checksum = get_u32(cp); if (checksum != stored_checksum) packet_disconnect("Corrupted check bytes on input."); buffer_consume_end(&incoming_packet, 4); @@ -977,6 +1052,8 @@ packet_read_poll1(void) buffer_len(&compression_buffer)); } type = buffer_get_char(&incoming_packet); + if (type < SSH_MSG_MIN || type > SSH_MSG_MAX) + packet_disconnect("Invalid ssh1 packet type: %d", type); return type; } @@ -986,7 +1063,7 @@ 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; + u_int maclen, block_size; Enc *enc = NULL; Mac *mac = NULL; Comp *comp = NULL; @@ -1011,9 +1088,11 @@ packet_read_poll2(u_int32_t *seqnr_p) cipher_crypt(&receive_context, cp, buffer_ptr(&input), block_size); cp = buffer_ptr(&incoming_packet); - packet_length = GET_32BIT(cp); + packet_length = get_u32(cp); if (packet_length < 1 + 4 || packet_length > 256 * 1024) { +#ifdef PACKET_DEBUG buffer_dump(&incoming_packet); +#endif packet_disconnect("Bad packet length %u.", packet_length); } DBG(debug("input: packet len %u", packet_length+4)); @@ -1055,7 +1134,7 @@ packet_read_poll2(u_int32_t *seqnr_p) if (seqnr_p != NULL) *seqnr_p = p_read.seqnr; if (++p_read.seqnr == 0) - log("incoming seqnr wraps around"); + logit("incoming seqnr wraps around"); if (++p_read.packets == 0) if (!(datafellows & SSH_BUG_NOREKEY)) fatal("XXX too many packets with same key"); @@ -1087,8 +1166,12 @@ packet_read_poll2(u_int32_t *seqnr_p) * return length of payload (without type field) */ type = buffer_get_char(&incoming_packet); + if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN) + packet_disconnect("Invalid ssh2 packet type: %d", type); if (type == SSH2_MSG_NEWKEYS) set_newkeys(MODE_IN); + else if (type == SSH2_MSG_USERAUTH_SUCCESS && !server_side) + packet_enable_delayed_compress(); #ifdef PACKET_DEBUG fprintf(stderr, "read/plain[%d]:\r\n", type); buffer_dump(&incoming_packet); @@ -1124,10 +1207,10 @@ packet_read_poll_seqnr(u_int32_t *seqnr_p) case SSH2_MSG_DISCONNECT: reason = packet_get_int(); msg = packet_get_string(NULL); - log("Received disconnect from %s: %u: %.400s", + logit("Received disconnect from %s: %u: %.400s", get_remote_ipaddr(), reason, msg); xfree(msg); - fatal_cleanup(); + cleanup_exit(255); break; case SSH2_MSG_UNIMPLEMENTED: seqnr = packet_get_int(); @@ -1136,7 +1219,6 @@ packet_read_poll_seqnr(u_int32_t *seqnr_p) break; default: return type; - break; } } else { type = packet_read_poll1(); @@ -1150,16 +1232,15 @@ packet_read_poll_seqnr(u_int32_t *seqnr_p) break; case SSH_MSG_DISCONNECT: msg = packet_get_string(NULL); - log("Received disconnect from %s: %.400s", + logit("Received disconnect from %s: %.400s", get_remote_ipaddr(), msg); - fatal_cleanup(); + cleanup_exit(255); xfree(msg); break; default: if (type) DBG(debug("received packet type %d", type)); return type; - break; } } } @@ -1219,9 +1300,9 @@ packet_get_bignum2(BIGNUM * value) } void * -packet_get_raw(int *length_ptr) +packet_get_raw(u_int *length_ptr) { - int bytes = buffer_len(&incoming_packet); + u_int bytes = buffer_len(&incoming_packet); if (length_ptr != NULL) *length_ptr = bytes; @@ -1309,7 +1390,7 @@ packet_disconnect(const char *fmt,...) va_end(args); /* Display the error locally */ - log("Disconnecting: %.100s", buf); + logit("Disconnecting: %.100s", buf); /* Send the disconnect message to the other side, and wait for it to get sent. */ if (compat20) { @@ -1329,8 +1410,7 @@ packet_disconnect(const char *fmt,...) /* Close the connection. */ packet_close(); - - fatal_cleanup(); + cleanup_exit(255); } /* Checks if there is any buffered output, and tries to write some of the output. */ @@ -1362,7 +1442,7 @@ packet_write_wait(void) { fd_set *setp; - setp = (fd_set *)xmalloc(howmany(connection_out + 1, NFDBITS) * + setp = (fd_set *)xcalloc(howmany(connection_out + 1, NFDBITS), sizeof(fd_mask)); packet_write_poll(); while (packet_have_data_to_write()) { @@ -1397,10 +1477,10 @@ packet_not_very_much_data_to_write(void) } -#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) static void packet_set_tos(int interactive) { +#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) int tos = interactive ? IPTOS_LOWDELAY : IPTOS_THROUGHPUT; if (!packet_connection_is_on_socket() || @@ -1410,8 +1490,8 @@ packet_set_tos(int interactive) sizeof(tos)) < 0) error("setsockopt IP_TOS %d: %.100s:", tos, strerror(errno)); -} #endif +} /* Informs that the current session is interactive. Sets IP flags for that. */ @@ -1429,12 +1509,9 @@ packet_set_interactive(int interactive) /* Only set socket options if using a socket. */ if (!packet_connection_is_on_socket()) - if (interactive) - set_nodelay(connection_in); -#if defined(IP_TOS) && !defined(IP_TOS_IS_BROKEN) + return; + set_nodelay(connection_in); packet_set_tos(interactive); -#endif - } /* Returns true if the current connection is interactive. */ @@ -1446,17 +1523,17 @@ packet_is_interactive(void) } int -packet_set_maxsize(int s) +packet_set_maxsize(u_int s) { static int called = 0; if (called) { - log("packet_set_maxsize: called twice: old %d new %d", + logit("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); + logit("packet_set_maxsize: bad size %d", s); return -1; } called = 1; @@ -1486,20 +1563,20 @@ packet_add_padding(u_char pad) void packet_send_ignore(int nbytes) { - u_int32_t rand = 0; + u_int32_t rnd = 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; + rnd = arc4random(); + packet_put_char((u_char)rnd & 0xff); + rnd >>= 8; } } -#define MAX_PACKETS (1<<31) +#define MAX_PACKETS (1U<<31) int packet_need_rekeying(void) { @@ -1517,3 +1594,15 @@ packet_set_rekey_limit(u_int32_t bytes) { rekey_limit = bytes; } + +void +packet_set_server(void) +{ + server_side = 1; +} + +void +packet_set_authenticated(void) +{ + after_authentication = 1; +}