cli-authpasswd.c revision 29698e296e3fd1474a362fbd229bca888175bb66 
1/*
2 * Dropbear SSH
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25#include "includes.h"
26#include "buffer.h"
27#include "dbutil.h"
28#include "session.h"
29#include "ssh.h"
30#include "runopts.h"
31
32#ifdef ENABLE_CLI_PASSWORD_AUTH
33
34#ifdef ENABLE_CLI_ASKPASS_HELPER
35/* Returns 1 if we want to use the askpass program, 0 otherwise */
36static int want_askpass()
37{
38	char* askpass_prog = NULL;
39
40	askpass_prog = getenv("SSH_ASKPASS");
41	return askpass_prog && !isatty(STDIN_FILENO) && getenv("DISPLAY");
42}
43
44/* returns a statically allocated password from a helper app, or NULL
45 * on failure */
46static char *gui_getpass(const char *prompt) {
47
48	pid_t pid;
49	int p[2], maxlen, len, status;
50	static char buf[DROPBEAR_MAX_CLI_PASS + 1];
51	char* helper = NULL;
52
53	TRACE(("enter gui_getpass"))
54
55	helper = getenv("SSH_ASKPASS");
56	if (!helper)
57	{
58		TRACE(("leave gui_getpass: no askpass program"))
59		return NULL;
60	}
61
62	if (pipe(p) < 0) {
63		TRACE(("error creating child pipe"))
64		return NULL;
65	}
66
67	pid = fork();
68
69	if (pid < 0) {
70		TRACE(("fork error"))
71		return NULL;
72	}
73
74	if (!pid) {
75		/* child */
76		close(p[0]);
77		if (dup2(p[1], STDOUT_FILENO) < 0) {
78			TRACE(("error redirecting stdout"))
79			exit(1);
80		}
81		close(p[1]);
82		execlp(helper, helper, prompt, (char *)0);
83		TRACE(("execlp error"))
84		exit(1);
85	}
86
87	close(p[1]);
88	maxlen = sizeof(buf);
89	while (maxlen > 0) {
90		len = read(p[0], buf + sizeof(buf) - maxlen, maxlen);
91		if (len > 0) {
92			maxlen -= len;
93		} else {
94			if (errno != EINTR)
95				break;
96		}
97	}
98
99	close(p[0]);
100
101	while (waitpid(pid, &status, 0) < 0 && errno == EINTR)
102		;
103	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
104		return(NULL);
105
106	len = sizeof(buf) - maxlen;
107	buf[len] = '\0';
108	if (len > 0 && buf[len - 1] == '\n')
109		buf[len - 1] = '\0';
110
111	TRACE(("leave gui_getpass"))
112	return(buf);
113}
114#endif /* ENABLE_CLI_ASKPASS_HELPER */
115
116void cli_auth_password() {
117
118	char* password = NULL;
119	char prompt[80];
120
121	TRACE(("enter cli_auth_password"))
122	CHECKCLEARTOWRITE();
123
124	snprintf(prompt, sizeof(prompt), "%s@%s's password: ",
125				cli_opts.username, cli_opts.remotehost);
126#ifdef ENABLE_CLI_ASKPASS_HELPER
127	if (want_askpass())
128		password = gui_getpass(prompt);
129	else
130#endif
131		password = getpass_or_cancel(prompt);
132
133	buf_putbyte(ses.writepayload, SSH_MSG_USERAUTH_REQUEST);
134
135	buf_putstring(ses.writepayload, cli_opts.username,
136			strlen(cli_opts.username));
137
138	buf_putstring(ses.writepayload, SSH_SERVICE_CONNECTION,
139			SSH_SERVICE_CONNECTION_LEN);
140
141	buf_putstring(ses.writepayload, AUTH_METHOD_PASSWORD,
142			AUTH_METHOD_PASSWORD_LEN);
143
144	buf_putbyte(ses.writepayload, 0); /* FALSE - so says the spec */
145
146	buf_putstring(ses.writepayload, password, strlen(password));
147
148	encrypt_packet();
149	m_burn(password, strlen(password));
150
151	TRACE(("leave cli_auth_password"))
152}
153#endif	/* ENABLE_CLI_PASSWORD_AUTH */
154