diff options
Diffstat (limited to 'packet.c')
| -rw-r--r-- | packet.c | 75 |
1 files changed, 68 insertions, 7 deletions
@@ -1,4 +1,4 @@ -/* $OpenBSD: packet.c,v 1.157 2008/07/10 18:08:11 markus Exp $ */ +/* $OpenBSD: packet.c,v 1.160 2009/02/13 11:50:21 markus Exp $ */ /* * Author: Tatu Ylonen <ylo@cs.hut.fi> * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland @@ -84,6 +84,8 @@ #define DBG(x) #endif +#define PACKET_MAX_SIZE (256 * 1024) + /* * This variable contains the file descriptors used for communicating with * the other side. connection_in is used for reading; connection_out for @@ -160,6 +162,10 @@ static u_int ssh1_keylen; /* roundup current message to extra_pad bytes */ static u_char extra_pad = 0; +/* XXX discard incoming data after MAC error */ +static u_int packet_discard = 0; +static Mac *packet_discard_mac = NULL; + struct packet { TAILQ_ENTRY(packet) next; u_char type; @@ -209,6 +215,36 @@ packet_set_timeout(int timeout, int count) packet_timeout_ms = timeout * count * 1000; } +static void +packet_stop_discard(void) +{ + if (packet_discard_mac) { + char buf[1024]; + + memset(buf, 'a', sizeof(buf)); + while (buffer_len(&incoming_packet) < PACKET_MAX_SIZE) + buffer_append(&incoming_packet, buf, sizeof(buf)); + (void) mac_compute(packet_discard_mac, + p_read.seqnr, + buffer_ptr(&incoming_packet), + PACKET_MAX_SIZE); + } + logit("Finished discarding for %.200s", get_remote_ipaddr()); + cleanup_exit(255); +} + +static void +packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard) +{ + if (enc == NULL || !cipher_is_cbc(enc->cipher)) + packet_disconnect("Packet corrupt"); + if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled) + packet_discard_mac = mac; + if (buffer_len(&input) >= discard) + packet_stop_discard(); + packet_discard = discard - buffer_len(&input); +} + /* Returns 1 if remote host is connected via socket, 0 if not. */ int @@ -1127,6 +1163,9 @@ packet_read_poll2(u_int32_t *seqnr_p) Mac *mac = NULL; Comp *comp = NULL; + if (packet_discard) + return SSH_MSG_NONE; + if (newkeys[MODE_IN] != NULL) { enc = &newkeys[MODE_IN]->enc; mac = &newkeys[MODE_IN]->mac; @@ -1148,11 +1187,14 @@ packet_read_poll2(u_int32_t *seqnr_p) block_size); cp = buffer_ptr(&incoming_packet); packet_length = get_u32(cp); - if (packet_length < 1 + 4 || packet_length > 256 * 1024) { + if (packet_length < 1 + 4 || packet_length > PACKET_MAX_SIZE) { #ifdef PACKET_DEBUG buffer_dump(&incoming_packet); #endif - packet_disconnect("Bad packet length %u.", packet_length); + logit("Bad packet length %u.", packet_length); + packet_start_discard(enc, mac, packet_length, + PACKET_MAX_SIZE); + return SSH_MSG_NONE; } DBG(debug("input: packet len %u", packet_length+4)); buffer_consume(&input, block_size); @@ -1161,9 +1203,13 @@ packet_read_poll2(u_int32_t *seqnr_p) 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", + if (need % block_size != 0) { + logit("padding error: need %d block %d mod %d", need, block_size, need % block_size); + packet_start_discard(enc, mac, packet_length, + PACKET_MAX_SIZE - block_size); + return SSH_MSG_NONE; + } /* * check if the entire packet has been received and * decrypt into incoming_packet @@ -1185,11 +1231,19 @@ packet_read_poll2(u_int32_t *seqnr_p) macbuf = mac_compute(mac, p_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."); + if (memcmp(macbuf, buffer_ptr(&input), mac->mac_len) != 0) { + logit("Corrupted MAC on input."); + if (need > PACKET_MAX_SIZE) + fatal("internal error need %d", need); + packet_start_discard(enc, mac, packet_length, + PACKET_MAX_SIZE - need); + return SSH_MSG_NONE; + } + DBG(debug("MAC #%d ok", p_read.seqnr)); buffer_consume(&input, mac->mac_len); } + /* XXX now it's safe to use fatal/packet_disconnect */ if (seqnr_p != NULL) *seqnr_p = p_read.seqnr; if (++p_read.seqnr == 0) @@ -1322,6 +1376,13 @@ packet_read_poll(void) void packet_process_incoming(const char *buf, u_int len) { + if (packet_discard) { + keep_alive_timeouts = 0; /* ?? */ + if (len >= packet_discard) + packet_stop_discard(); + packet_discard -= len; + return; + } buffer_append(&input, buf, len); } |
