1/*
2 * Dropbear SSH
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * Copyright (c) 2004 by Mihnea Stoenescu
6 * All rights reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 * SOFTWARE. */
25
26#include "includes.h"
27#include "buffer.h"
28#include "dbutil.h"
29#include "session.h"
30#include "ssh.h"
31#include "runopts.h"
32#include "auth.h"
33
34#ifdef ENABLE_CLI_PUBKEY_AUTH
35static void send_msg_userauth_pubkey(sign_key *key, int type, int realsign);
36
37/* Called when we receive a SSH_MSG_USERAUTH_FAILURE for a pubkey request.
38 * We use it to remove the key we tried from the list */
39void cli_pubkeyfail() {
40
41	struct SignKeyList *keyitem;
42	struct SignKeyList **previtem;
43
44	TRACE(("enter cli_pubkeyfail"))
45	previtem = &cli_opts.privkeys;
46
47	/* Find the key we failed with, and remove it */
48	for (keyitem = cli_opts.privkeys; keyitem != NULL; keyitem = keyitem->next) {
49		if (keyitem == cli_ses.lastprivkey) {
50			*previtem = keyitem->next;
51		}
52		previtem = &keyitem;
53	}
54
55	sign_key_free(cli_ses.lastprivkey->key); /* It won't be used again */
56	m_free(cli_ses.lastprivkey);
57
58	TRACE(("leave cli_pubkeyfail"))
59}
60
61void recv_msg_userauth_pk_ok() {
62
63	struct SignKeyList *keyitem = NULL;
64	buffer* keybuf = NULL;
65	char* algotype = NULL;
66	unsigned int algolen;
67	int keytype;
68	unsigned int remotelen;
69
70	TRACE(("enter recv_msg_userauth_pk_ok"))
71
72	algotype = buf_getstring(ses.payload, &algolen);
73	keytype = signkey_type_from_name(algotype, algolen);
74	TRACE(("recv_msg_userauth_pk_ok: type %d", keytype))
75	m_free(algotype);
76
77	keybuf = buf_new(MAX_PUBKEY_SIZE);
78
79	remotelen = buf_getint(ses.payload);
80
81	/* Iterate through our keys, find which one it was that matched, and
82	 * send a real request with that key */
83	for (keyitem = cli_opts.privkeys; keyitem != NULL; keyitem = keyitem->next) {
84
85		if (keyitem->type != keytype) {
86			/* Types differed */
87			TRACE(("types differed"))
88			continue;
89		}
90
91		/* Now we compare the contents of the key */
92		keybuf->pos = keybuf->len = 0;
93		buf_put_pub_key(keybuf, keyitem->key, keytype);
94		buf_setpos(keybuf, 0);
95		buf_incrpos(keybuf, 4); /* first int is the length of the remainder (ie
96								   remotelen) which has already been taken from
97								   the remote buffer */
98
99
100		if (keybuf->len-4 != remotelen) {
101			TRACE(("lengths differed: localh %d remote %d", keybuf->len, remotelen))
102			/* Lengths differed */
103			continue;
104		}
105		if (memcmp(buf_getptr(keybuf, remotelen),
106					buf_getptr(ses.payload, remotelen), remotelen) != 0) {
107			/* Data didn't match this key */
108			TRACE(("data differed"))
109			continue;
110		}
111
112		/* Success */
113		break;
114	}
115	buf_free(keybuf);
116
117	if (keyitem != NULL) {
118		TRACE(("matching key"))
119		/* XXX TODO: if it's an encrypted key, here we ask for their
120		 * password */
121		send_msg_userauth_pubkey(keyitem->key, keytype, 1);
122	} else {
123		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"))
124	}
125
126	TRACE(("leave recv_msg_userauth_pk_ok"))
127}
128
129/* TODO: make it take an agent reference to use as well */
130static void send_msg_userauth_pubkey(sign_key *key, int type, int realsign) {
131
132	const char *algoname = NULL;
133	int algolen;
134	buffer* sigbuf = NULL;
135
136	TRACE(("enter send_msg_userauth_pubkey"))
137	CHECKCLEARTOWRITE();
138
139	buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);
140
141	buf_putstring(ses.writepayload, cli_opts.username,
142			strlen(cli_opts.username));
143
144	buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION,
145			SSH_SERVICE_CONNECTION_LEN);
146
147	buf_putstring(ses.writepayload, AUTH_METHOD_PUBKEY,
148			AUTH_METHOD_PUBKEY_LEN);
149
150	buf_putbyte(ses.writepayload, realsign);
151
152	algoname = signkey_name_from_type(type, &algolen);
153
154	buf_putstring(ses.writepayload, algoname, algolen);
155	buf_put_pub_key(ses.writepayload, key, type);
156
157	if (realsign) {
158		TRACE(("realsign"))
159		/* We put the signature as well - this contains string(session id), then
160		 * the contents of the write payload to this point */
161		sigbuf = buf_new(4 + SHA1_HASH_SIZE + ses.writepayload->len);
162		buf_putstring(sigbuf, ses.session_id, SHA1_HASH_SIZE);
163		buf_putbytes(sigbuf, ses.writepayload->data, ses.writepayload->len);
164		buf_put_sign(ses.writepayload, key, type, sigbuf->data, sigbuf->len);
165		buf_free(sigbuf); /* Nothing confidential in the buffer */
166	}
167
168	encrypt_packet();
169	TRACE(("leave send_msg_userauth_pubkey"))
170}
171
172int cli_auth_pubkey() {
173
174	TRACE(("enter cli_auth_pubkey"))
175
176	if (cli_opts.privkeys != NULL) {
177		/* Send a trial request */
178		send_msg_userauth_pubkey(cli_opts.privkeys->key,
179				cli_opts.privkeys->type, 0);
180		cli_ses.lastprivkey = cli_opts.privkeys;
181		TRACE(("leave cli_auth_pubkey-success"))
182		return 1;
183	} else {
184		TRACE(("leave cli_auth_pubkey-failure"))
185		return 0;
186	}
187}
188#endif /* Pubkey auth */
189