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
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
/*
* Dropbear SSH
*
* Copyright (c) 2002,2003 Matt Johnston
* Copyright (c) 2004 by Mihnea Stoenescu
* 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 "buffer.h"
#include "dbutil.h"
#include "session.h"
#include "ssh.h"
#include "runopts.h"
#include "auth.h"
#include "agentfwd.h"
#ifdef ENABLE_CLI_PUBKEY_AUTH
static void send_msg_userauth_pubkey(sign_key *key, int type, int realsign);
/* Called when we receive a SSH_MSG_USERAUTH_FAILURE for a pubkey request.
* We use it to remove the key we tried from the list */
void cli_pubkeyfail() {
m_list_elem *iter;
for (iter = cli_opts.privkeys->first; iter; iter = iter->next) {
sign_key *iter_key = (sign_key*)iter->item;
if (iter_key == cli_ses.lastprivkey)
{
/* found the failing key */
list_remove(iter);
sign_key_free(iter_key);
cli_ses.lastprivkey = NULL;
return;
}
}
}
void recv_msg_userauth_pk_ok() {
m_list_elem *iter;
buffer* keybuf = NULL;
char* algotype = NULL;
unsigned int algolen;
enum signkey_type keytype;
unsigned int remotelen;
TRACE(("enter recv_msg_userauth_pk_ok"))
algotype = buf_getstring(ses.payload, &algolen);
keytype = signkey_type_from_name(algotype, algolen);
TRACE(("recv_msg_userauth_pk_ok: type %d", keytype))
m_free(algotype);
keybuf = buf_new(MAX_PUBKEY_SIZE);
remotelen = buf_getint(ses.payload);
/* Iterate through our keys, find which one it was that matched, and
* send a real request with that key */
for (iter = cli_opts.privkeys->first; iter; iter = iter->next) {
sign_key *key = (sign_key*)iter->item;
if (key->type != keytype) {
/* Types differed */
TRACE(("types differed"))
continue;
}
/* Now we compare the contents of the key */
keybuf->pos = keybuf->len = 0;
buf_put_pub_key(keybuf, key, keytype);
buf_setpos(keybuf, 0);
buf_incrpos(keybuf, 4); /* first int is the length of the remainder (ie
remotelen) which has already been taken from
the remote buffer */
if (keybuf->len-4 != remotelen) {
TRACE(("lengths differed: localh %d remote %d", keybuf->len, remotelen))
/* Lengths differed */
continue;
}
if (memcmp(buf_getptr(keybuf, remotelen),
buf_getptr(ses.payload, remotelen), remotelen) != 0) {
/* Data didn't match this key */
TRACE(("data differed"))
continue;
}
/* Success */
break;
}
buf_free(keybuf);
if (iter != NULL) {
TRACE(("matching key"))
/* XXX TODO: if it's an encrypted key, here we ask for their
* password */
send_msg_userauth_pubkey((sign_key*)iter->item, keytype, 1);
} else {
TRACE(("That was whacky. We got told that a key was valid, but it didn't match our list. Sounds like dodgy code on Dropbear's part"))
}
TRACE(("leave recv_msg_userauth_pk_ok"))
}
void cli_buf_put_sign(buffer* buf, sign_key *key, int type,
buffer *data_buf) {
#ifdef ENABLE_CLI_AGENTFWD
if (key->source == SIGNKEY_SOURCE_AGENT) {
/* Format the agent signature ourselves, as buf_put_sign would. */
buffer *sigblob;
sigblob = buf_new(MAX_PUBKEY_SIZE);
agent_buf_sign(sigblob, key, data_buf);
buf_putbufstring(buf, sigblob);
buf_free(sigblob);
} else
#endif /* ENABLE_CLI_AGENTFWD */
{
buf_put_sign(buf, key, type, data_buf);
}
}
/* TODO: make it take an agent reference to use as well */
static void send_msg_userauth_pubkey(sign_key *key, int type, int realsign) {
const char *algoname = NULL;
int algolen;
buffer* sigbuf = NULL;
TRACE(("enter send_msg_userauth_pubkey"))
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);
buf_putstring(ses.writepayload, cli_opts.username,
strlen(cli_opts.username));
buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION,
SSH_SERVICE_CONNECTION_LEN);
buf_putstring(ses.writepayload, AUTH_METHOD_PUBKEY,
AUTH_METHOD_PUBKEY_LEN);
buf_putbyte(ses.writepayload, realsign);
algoname = signkey_name_from_type(type, &algolen);
buf_putstring(ses.writepayload, algoname, algolen);
buf_put_pub_key(ses.writepayload, key, type);
if (realsign) {
TRACE(("realsign"))
/* We put the signature as well - this contains string(session id), then
* the contents of the write payload to this point */
sigbuf = buf_new(4 + ses.session_id->len + ses.writepayload->len);
buf_putbufstring(sigbuf, ses.session_id);
buf_putbytes(sigbuf, ses.writepayload->data, ses.writepayload->len);
cli_buf_put_sign(ses.writepayload, key, type, sigbuf);
buf_free(sigbuf); /* Nothing confidential in the buffer */
}
encrypt_packet();
TRACE(("leave send_msg_userauth_pubkey"))
}
/* Returns 1 if a key was tried */
int cli_auth_pubkey() {
TRACE(("enter cli_auth_pubkey"))
#ifdef ENABLE_CLI_AGENTFWD
if (!cli_opts.agent_keys_loaded) {
/* get the list of available keys from the agent */
cli_load_agent_keys(cli_opts.privkeys);
cli_opts.agent_keys_loaded = 1;
}
#endif
if (cli_opts.privkeys->first) {
sign_key * key = (sign_key*)cli_opts.privkeys->first->item;
/* Send a trial request */
send_msg_userauth_pubkey(key, key->type, 0);
cli_ses.lastprivkey = key;
TRACE(("leave cli_auth_pubkey-success"))
return 1;
} else {
/* no more keys left */
TRACE(("leave cli_auth_pubkey-failure"))
return 0;
}
}
void cli_auth_pubkey_cleanup() {
#ifdef ENABLE_CLI_AGENTFWD
m_close(cli_opts.agent_fd);
cli_opts.agent_fd = -1;
#endif
while (cli_opts.privkeys->first) {
sign_key * key = list_remove(cli_opts.privkeys->first);
sign_key_free(key);
}
}
#endif /* Pubkey auth */
|
