146 lines
4.0 KiB
C
146 lines
4.0 KiB
C
/*
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* Dropbear - a SSH2 server
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*
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* Copyright (c) 2002-2004 Matt Johnston
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* All rights reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE. */
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#include "includes.h"
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#include "packet.h"
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#include "session.h"
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#include "dbutil.h"
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#include "ssh.h"
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#include "algo.h"
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#include "buffer.h"
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#include "kex.h"
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#include "random.h"
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#include "service.h"
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#include "auth.h"
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#include "channel.h"
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#define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
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static void recv_unimplemented();
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/* process a decrypted packet, call the appropriate handler */
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void process_packet() {
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unsigned char type;
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unsigned int i;
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TRACE(("enter process_packet"))
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type = buf_getbyte(ses.payload);
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TRACE(("process_packet: packet type = %d", type))
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ses.lastpacket = type;
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ses.last_packet_time = time(NULL);
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/* These packets we can receive at any time */
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switch(type) {
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case SSH_MSG_IGNORE:
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goto out;
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case SSH_MSG_DEBUG:
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goto out;
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case SSH_MSG_UNIMPLEMENTED:
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/* debugging XXX */
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TRACE(("SSH_MSG_UNIMPLEMENTED"))
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dropbear_exit("Received SSH_MSG_UNIMPLEMENTED");
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case SSH_MSG_DISCONNECT:
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/* TODO cleanup? */
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dropbear_close("Disconnect received");
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}
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/* This applies for KEX, where the spec says the next packet MUST be
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* NEWKEYS */
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if (ses.requirenext != 0) {
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if (ses.requirenext != type) {
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/* TODO send disconnect? */
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dropbear_exit("Unexpected packet type %d, expected %d", type,
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ses.requirenext);
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} else {
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/* Got what we expected */
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ses.requirenext = 0;
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}
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}
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/* Check if we should ignore this packet. Used currently only for
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* KEX code, with first_kex_packet_follows */
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if (ses.ignorenext) {
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TRACE(("Ignoring packet, type = %d", type))
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ses.ignorenext = 0;
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goto out;
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}
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/* Kindly the protocol authors gave all the preauth packets type values
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* less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
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* NOTE: if the protocol changes and new types are added, revisit this
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* assumption */
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if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
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dropbear_exit("Received message %d before userauth", type);
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}
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for (i = 0; ; i++) {
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if (ses.packettypes[i].type == 0) {
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/* end of list */
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break;
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}
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if (ses.packettypes[i].type == type) {
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ses.packettypes[i].handler();
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goto out;
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}
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}
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/* TODO do something more here? */
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TRACE(("preauth unknown packet"))
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recv_unimplemented();
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out:
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buf_free(ses.payload);
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ses.payload = NULL;
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TRACE(("leave process_packet"))
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}
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/* This must be called directly after receiving the unimplemented packet.
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* Isn't the most clean implementation, it relies on packet processing
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* occurring directly after decryption (direct use of ses.recvseq).
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* This is reasonably valid, since there is only a single decryption buffer */
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static void recv_unimplemented() {
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CHECKCLEARTOWRITE();
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buf_putbyte(ses.writepayload, SSH_MSG_UNIMPLEMENTED);
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/* the decryption routine increments the sequence number, we must
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* decrement */
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buf_putint(ses.writepayload, ses.recvseq - 1);
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encrypt_packet();
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}
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