1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Dropbear - a SSH2 server
*
* Copyright (c) 2002-2004 Matt Johnston
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE. */
#include "includes.h"
#include "packet.h"
#include "session.h"
#include "dbutil.h"
#include "ssh.h"
#include "algo.h"
#include "buffer.h"
#include "kex.h"
#include "random.h"
#include "service.h"
#include "auth.h"
#include "channel.h"
#define MAX_UNAUTH_PACKET_TYPE SSH_MSG_USERAUTH_PK_OK
static void recv_unimplemented();
/* process a decrypted packet, call the appropriate handler */
void process_packet() {
unsigned char type;
unsigned int i;
TRACE(("enter process_packet"))
type = buf_getbyte(ses.payload);
TRACE(("process_packet: packet type = %d", type))
ses.lastpacket = type;
/* These packets we can receive at any time */
switch(type) {
case SSH_MSG_IGNORE:
case SSH_MSG_DEBUG:
TRACE(("received SSH_MSG_IGNORE or SSH_MSG_DEBUG"))
goto out;
case SSH_MSG_UNIMPLEMENTED:
/* debugging XXX */
TRACE(("SSH_MSG_UNIMPLEMENTED"))
dropbear_exit("received SSH_MSG_UNIMPLEMENTED");
case SSH_MSG_DISCONNECT:
/* TODO cleanup? */
dropbear_close("Disconnect received");
}
/* This applies for KEX, where the spec says the next packet MUST be
* NEWKEYS */
if (ses.requirenext != 0) {
if (ses.requirenext != type) {
/* TODO send disconnect? */
dropbear_exit("unexpected packet type %d, expected %d", type,
ses.requirenext);
} else {
/* Got what we expected */
ses.requirenext = 0;
}
}
/* Check if we should ignore this packet. Used currently only for
* KEX code, with first_kex_packet_follows */
if (ses.ignorenext) {
TRACE(("Ignoring packet, type = %d", type))
ses.ignorenext = 0;
goto out;
}
/* Kindly the protocol authors gave all the preauth packets type values
* less-than-or-equal-to 60 ( == MAX_UNAUTH_PACKET_TYPE ).
* NOTE: if the protocol changes and new types are added, revisit this
* assumption */
if ( !ses.authstate.authdone && type > MAX_UNAUTH_PACKET_TYPE ) {
dropbear_exit("received message %d before userauth", type);
}
for (i = 0; ; i++) {
if (ses.packettypes[i].type == 0) {
/* end of list */
break;
}
if (ses.packettypes[i].type == type) {
ses.packettypes[i].handler();
goto out;
}
}
/* TODO do something more here? */
TRACE(("preauth unknown packet"))
recv_unimplemented();
out:
buf_burn(ses.payload); /* Clear the memory to avoid swapping it out */
buf_free(ses.payload);
ses.payload = NULL;
TRACE(("leave process_packet"))
}
/* This must be called directly after receiving the unimplemented packet.
* Isn't the most clean implementation, it relies on packet processing
* occurring directly after decryption (direct use of ses.recvseq).
* This is reasonably valid, since there is only a single decryption buffer */
static void recv_unimplemented() {
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_UNIMPLEMENTED);
/* the decryption routine increments the sequence number, we must
* decrement */
buf_putint(ses.writepayload, ses.recvseq - 1);
encrypt_packet();
}
|
