107 lines
3.3 KiB
C
107 lines
3.3 KiB
C
/*
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* Dropbear - a SSH2 server
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*
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* Copyright (c) 2002,2003 Matt Johnston
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* Copyright (c) 2004 by Mihnea Stoenescu
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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 "dbutil.h"
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#include "algo.h"
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#include "buffer.h"
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#include "session.h"
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#include "kex.h"
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#include "ssh.h"
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#include "packet.h"
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#include "bignum.h"
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#include "random.h"
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#include "runopts.h"
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static void send_msg_kexdh_reply(mp_int *dh_e);
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/* Handle a diffie-hellman key exchange initialisation. This involves
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* calculating a session key reply value, and corresponding hash. These
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* are carried out by send_msg_kexdh_reply(). recv_msg_kexdh_init() calls
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* that function, then brings the new keys into use */
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void recv_msg_kexdh_init() {
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DEF_MP_INT(dh_e);
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TRACE(("enter recv_msg_kexdh_init"))
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if (!ses.kexstate.recvkexinit) {
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dropbear_exit("Premature kexdh_init message received");
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}
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m_mp_init(&dh_e);
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if (buf_getmpint(ses.payload, &dh_e) != DROPBEAR_SUCCESS) {
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dropbear_exit("Failed to get kex value");
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}
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send_msg_kexdh_reply(&dh_e);
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mp_clear(&dh_e);
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send_msg_newkeys();
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ses.requirenext = SSH_MSG_NEWKEYS;
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TRACE(("leave recv_msg_kexdh_init"))
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}
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/* Generate our side of the diffie-hellman key exchange value (dh_f), and
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* calculate the session key using the diffie-hellman algorithm. Following
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* that, the session hash is calculated, and signed with RSA or DSS. The
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* result is sent to the client.
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*
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* See the transport rfc 4253 section 8 for details */
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static void send_msg_kexdh_reply(mp_int *dh_e) {
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DEF_MP_INT(dh_y);
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DEF_MP_INT(dh_f);
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TRACE(("enter send_msg_kexdh_reply"))
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m_mp_init_multi(&dh_y, &dh_f, NULL);
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gen_kexdh_vals(&dh_f, &dh_y);
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kexdh_comb_key(&dh_f, &dh_y, dh_e, svr_opts.hostkey);
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mp_clear(&dh_y);
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/* we can start creating the kexdh_reply packet */
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CHECKCLEARTOWRITE();
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buf_putbyte(ses.writepayload, SSH_MSG_KEXDH_REPLY);
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buf_put_pub_key(ses.writepayload, svr_opts.hostkey,
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ses.newkeys->algo_hostkey);
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/* put f */
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buf_putmpint(ses.writepayload, &dh_f);
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mp_clear(&dh_f);
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/* calc the signature */
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buf_put_sign(ses.writepayload, svr_opts.hostkey,
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ses.newkeys->algo_hostkey, ses.hash, SHA1_HASH_SIZE);
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/* the SSH_MSG_KEXDH_REPLY is done */
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encrypt_packet();
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TRACE(("leave send_msg_kexdh_reply"))
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}
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