annotate svr-service.c @ 994:5c5ade336926

Prefer stronger algorithms in algorithm negotiation. Prefer diffie-hellman-group14-sha1 (2048 bit) over diffie-hellman-group1-sha1 (1024 bit). Due to meet-in-the-middle attacks the effective key length of three key 3DES is 112 bits. AES is stronger and faster then 3DES. Prefer to delay the start of compression until after authentication has completed. This avoids exposing compression code to attacks from unauthenticated users. (github pull request #9)
author Fedor Brunner <fedor.brunner@azet.sk>
date Fri, 23 Jan 2015 23:00:25 +0800
parents a98a2138364a
children 848dac90c923
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1 /*
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2 * Dropbear - a SSH2 server
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3 *
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4 * Copyright (c) 2002,2003 Matt Johnston
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5 * All rights reserved.
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6 *
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7 * Permission is hereby granted, free of charge, to any person obtaining a copy
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8 * of this software and associated documentation files (the "Software"), to deal
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9 * in the Software without restriction, including without limitation the rights
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10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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11 * copies of the Software, and to permit persons to whom the Software is
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12 * furnished to do so, subject to the following conditions:
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13 *
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14 * The above copyright notice and this permission notice shall be included in
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15 * all copies or substantial portions of the Software.
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16 *
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17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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23 * SOFTWARE. */
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24
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25 #include "includes.h"
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26 #include "dbutil.h"
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27 #include "service.h"
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28 #include "session.h"
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29 #include "packet.h"
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30 #include "ssh.h"
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31 #include "auth.h"
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33 static void send_msg_service_accept(unsigned char *name, int len);
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35 /* processes a SSH_MSG_SERVICE_REQUEST, returning 0 if finished,
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36 * 1 if not */
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37 void recv_msg_service_request() {
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39 unsigned char * name;
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40 unsigned int len;
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41
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42 TRACE(("enter recv_msg_service_request"))
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44 name = buf_getstring(ses.payload, &len);
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46 /* ssh-userauth */
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47 if (len == SSH_SERVICE_USERAUTH_LEN &&
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48 strncmp(SSH_SERVICE_USERAUTH, name, len) == 0) {
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50 send_msg_service_accept(name, len);
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51 m_free(name);
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52 TRACE(("leave recv_msg_service_request: done ssh-userauth"))
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53 return;
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54 }
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56 /* ssh-connection */
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57 if (len == SSH_SERVICE_CONNECTION_LEN &&
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58 (strncmp(SSH_SERVICE_CONNECTION, name, len) == 0)) {
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59 if (ses.authstate.authdone != 1) {
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60 dropbear_exit("Request for connection before auth");
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61 }
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63 send_msg_service_accept(name, len);
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64 m_free(name);
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65 TRACE(("leave recv_msg_service_request: done ssh-connection"))
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66 return;
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67 }
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69 m_free(name);
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70 /* TODO this should be a MSG_DISCONNECT */
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71 dropbear_exit("Unrecognised SSH_MSG_SERVICE_REQUEST");
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74 }
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76 static void send_msg_service_accept(unsigned char *name, int len) {
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78 TRACE(("accepting service %s", name))
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80 CHECKCLEARTOWRITE();
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82 buf_putbyte(ses.writepayload, SSH_MSG_SERVICE_ACCEPT);
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83 buf_putstring(ses.writepayload, name, len);
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85 encrypt_packet();
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86
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87 }