annotate svr-kex.c @ 41:18eccbfb9641

added window-size change handling
author Matt Johnston <matt@ucc.asn.au>
date Sun, 01 Aug 2004 09:41:37 +0000
parents 0969767bca0d
children e3adf4cf5465
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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 "algo.h"
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28 #include "buffer.h"
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29 #include "session.h"
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30 #include "kex.h"
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31 #include "ssh.h"
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32 #include "packet.h"
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33 #include "bignum.h"
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34 #include "random.h"
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35 #include "runopts.h"
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38 static void send_msg_kexdh_reply(mp_int *dh_e);
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39
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40 /* Handle a diffie-hellman key exchange initialisation. This involves
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41 * calculating a session key reply value, and corresponding hash. These
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42 * are carried out by send_msg_kexdh_reply(). recv_msg_kexdh_init() calls
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43 * that function, then brings the new keys into use */
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44 void recv_msg_kexdh_init() {
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45
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46 mp_int dh_e;
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47
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48 TRACE(("enter recv_msg_kexdh_init"));
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49 if (!ses.kexstate.recvkexinit) {
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50 dropbear_exit("Premature kexdh_init message received");
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51 }
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52
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53 m_mp_init(&dh_e);
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54 buf_getmpint(ses.payload, &dh_e);
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56 send_msg_kexdh_reply(&dh_e);
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58 mp_clear(&dh_e);
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59
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60 send_msg_newkeys();
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61 ses.requirenext = SSH_MSG_NEWKEYS;
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62 TRACE(("leave recv_msg_kexdh_init"));
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63 }
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64
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65 /* Generate our side of the diffie-hellman key exchange value (dh_f), and
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66 * calculate the session key using the diffie-hellman algorithm. Following
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67 * that, the session hash is calculated, and signed with RSA or DSS. The
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68 * result is sent to the client.
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69 *
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70 * See the ietf-secsh-transport draft, section 6, for details */
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71 static void send_msg_kexdh_reply(mp_int *dh_e) {
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72
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73 mp_int dh_y, dh_f;
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75 TRACE(("enter send_msg_kexdh_reply"));
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76
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77 gen_kexdh_vals(&dh_f, &dh_y);
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78
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79 kexdh_comb_key(&dh_f, &dh_y, dh_e, svr_opts.hostkey);
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80 mp_clear(&dh_y);
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81
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82 /* we can start creating the kexdh_reply packet */
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83 CHECKCLEARTOWRITE();
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84 buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY);
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85 buf_put_pub_key(ses.writepayload, svr_opts.hostkey,
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86 ses.newkeys->algo_hostkey);
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87
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88 /* put f */
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89 buf_putmpint(ses.writepayload, &dh_f);
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90 mp_clear(&dh_f);
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91
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92 /* calc the signature */
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93 buf_put_sign(ses.writepayload, svr_opts.hostkey,
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94 ses.newkeys->algo_hostkey, ses.hash, SHA1_HASH_SIZE);
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95
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96 /* the SSH_MSG_KEXDH_REPLY is done */
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97 encrypt_packet();
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98
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99 TRACE(("leave send_msg_kexdh_reply"));
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100 }
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101