readpass.c revision 92555 
1/*
2 * Copyright (c) 2001 Markus Friedl.  All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23 */
24
25#include "includes.h"
26RCSID("$OpenBSD: readpass.c,v 1.26 2002/02/13 00:39:15 markus Exp $");
27
28#include <readpassphrase.h>
29
30#include "xmalloc.h"
31#include "readpass.h"
32#include "pathnames.h"
33#include "log.h"
34#include "ssh.h"
35
36static char *
37ssh_askpass(char *askpass, const char *msg)
38{
39	pid_t pid;
40	size_t len;
41	char *pass;
42	int p[2], status, ret;
43	char buf[1024];
44
45	if (fflush(stdout) != 0)
46		error("ssh_askpass: fflush: %s", strerror(errno));
47	if (askpass == NULL)
48		fatal("internal error: askpass undefined");
49	if (pipe(p) < 0) {
50		error("ssh_askpass: pipe: %s", strerror(errno));
51		return xstrdup("");
52	}
53	if ((pid = fork()) < 0) {
54		error("ssh_askpass: fork: %s", strerror(errno));
55		return xstrdup("");
56	}
57	if (pid == 0) {
58		seteuid(getuid());
59		setuid(getuid());
60		close(p[0]);
61		if (dup2(p[1], STDOUT_FILENO) < 0)
62			fatal("ssh_askpass: dup2: %s", strerror(errno));
63		execlp(askpass, askpass, msg, (char *) 0);
64		fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
65	}
66	close(p[1]);
67
68	len = ret = 0;
69	do {
70		ret = read(p[0], buf + len, sizeof(buf) - 1 - len);
71		if (ret == -1 && errno == EINTR)
72			continue;
73		if (ret <= 0)
74			break;
75		len += ret;
76	} while (sizeof(buf) - 1 - len > 0);
77	buf[len] = '\0';
78
79	close(p[0]);
80	while (waitpid(pid, &status, 0) < 0)
81		if (errno != EINTR)
82			break;
83
84	buf[strcspn(buf, "\r\n")] = '\0';
85	pass = xstrdup(buf);
86	memset(buf, 0, sizeof(buf));
87	return pass;
88}
89
90/*
91 * Reads a passphrase from /dev/tty with echo turned off/on.  Returns the
92 * passphrase (allocated with xmalloc).  Exits if EOF is encountered. If
93 * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
94 * tty is available
95 */
96char *
97read_passphrase(const char *prompt, int flags)
98{
99	char *askpass = NULL, *ret, buf[1024];
100	int rppflags, use_askpass = 0, ttyfd;
101
102	rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
103	if (flags & RP_ALLOW_STDIN) {
104		if (!isatty(STDIN_FILENO))
105			use_askpass = 1;
106	} else {
107		rppflags |= RPP_REQUIRE_TTY;
108		ttyfd = open(_PATH_TTY, O_RDWR);
109		if (ttyfd >= 0)
110			close(ttyfd);
111		else
112			use_askpass = 1;
113	}
114
115	if (use_askpass && getenv("DISPLAY")) {
116		if (getenv(SSH_ASKPASS_ENV))
117			askpass = getenv(SSH_ASKPASS_ENV);
118		else
119			askpass = _PATH_SSH_ASKPASS_DEFAULT;
120		return ssh_askpass(askpass, prompt);
121	}
122
123	if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL)
124		return xstrdup("");
125
126	ret = xstrdup(buf);
127	memset(buf, 'x', sizeof buf);
128	return ret;
129}
130