readpassphrase.c revision 215236 
1/*	$OpenBSD: readpassphrase.c,v 1.23 2010/05/14 13:30:34 millert Exp $	*/
2
3/*
4 * Copyright (c) 2000-2002, 2007, 2010
5 *	Todd C. Miller <Todd.Miller@courtesan.com>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 *
19 * Sponsored in part by the Defense Advanced Research Projects
20 * Agency (DARPA) and Air Force Research Laboratory, Air Force
21 * Materiel Command, USAF, under agreement number F39502-99-1-0512.
22 */
23
24#include <sys/cdefs.h>
25__FBSDID("$FreeBSD: head/lib/libc/gen/readpassphrase.c 215236 2010-11-13 10:38:06Z delphij $");
26
27#include "namespace.h"
28#include <ctype.h>
29#include <errno.h>
30#include <fcntl.h>
31#include <paths.h>
32#include <pwd.h>
33#include <signal.h>
34#include <string.h>
35#include <termios.h>
36#include <unistd.h>
37#include <readpassphrase.h>
38#include "un-namespace.h"
39
40static volatile sig_atomic_t signo[NSIG];
41
42static void handler(int);
43
44char *
45readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
46{
47	ssize_t nr;
48	int input, output, save_errno, i, need_restart;
49	char ch, *p, *end;
50	struct termios term, oterm;
51	struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;
52	struct sigaction savetstp, savettin, savettou, savepipe;
53
54	/* I suppose we could alloc on demand in this case (XXX). */
55	if (bufsiz == 0) {
56		errno = EINVAL;
57		return(NULL);
58	}
59
60restart:
61	for (i = 0; i < NSIG; i++)
62		signo[i] = 0;
63	nr = -1;
64	save_errno = 0;
65	need_restart = 0;
66	/*
67	 * Read and write to /dev/tty if available.  If not, read from
68	 * stdin and write to stderr unless a tty is required.
69	 */
70	if ((flags & RPP_STDIN) ||
71	    (input = output = _open(_PATH_TTY, O_RDWR)) == -1) {
72		if (flags & RPP_REQUIRE_TTY) {
73			errno = ENOTTY;
74			return(NULL);
75		}
76		input = STDIN_FILENO;
77		output = STDERR_FILENO;
78	}
79
80	/*
81	 * Turn off echo if possible.
82	 * If we are using a tty but are not the foreground pgrp this will
83	 * generate SIGTTOU, so do it *before* installing the signal handlers.
84	 */
85	if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) {
86		memcpy(&term, &oterm, sizeof(term));
87		if (!(flags & RPP_ECHO_ON))
88			term.c_lflag &= ~(ECHO | ECHONL);
89		if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)
90			term.c_cc[VSTATUS] = _POSIX_VDISABLE;
91		(void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);
92	} else {
93		memset(&term, 0, sizeof(term));
94		term.c_lflag |= ECHO;
95		memset(&oterm, 0, sizeof(oterm));
96		oterm.c_lflag |= ECHO;
97	}
98
99	/*
100	 * Catch signals that would otherwise cause the user to end
101	 * up with echo turned off in the shell.  Don't worry about
102	 * things like SIGXCPU and SIGVTALRM for now.
103	 */
104	sigemptyset(&sa.sa_mask);
105	sa.sa_flags = 0;		/* don't restart system calls */
106	sa.sa_handler = handler;
107	(void)_sigaction(SIGALRM, &sa, &savealrm);
108	(void)_sigaction(SIGHUP, &sa, &savehup);
109	(void)_sigaction(SIGINT, &sa, &saveint);
110	(void)_sigaction(SIGPIPE, &sa, &savepipe);
111	(void)_sigaction(SIGQUIT, &sa, &savequit);
112	(void)_sigaction(SIGTERM, &sa, &saveterm);
113	(void)_sigaction(SIGTSTP, &sa, &savetstp);
114	(void)_sigaction(SIGTTIN, &sa, &savettin);
115	(void)_sigaction(SIGTTOU, &sa, &savettou);
116
117	if (!(flags & RPP_STDIN))
118		(void)_write(output, prompt, strlen(prompt));
119	end = buf + bufsiz - 1;
120	p = buf;
121	while ((nr = _read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
122		if (p < end) {
123			if ((flags & RPP_SEVENBIT))
124				ch &= 0x7f;
125			if (isalpha(ch)) {
126				if ((flags & RPP_FORCELOWER))
127					ch = (char)tolower(ch);
128				if ((flags & RPP_FORCEUPPER))
129					ch = (char)toupper(ch);
130			}
131			*p++ = ch;
132		}
133	}
134	*p = '\0';
135	save_errno = errno;
136	if (!(term.c_lflag & ECHO))
137		(void)_write(output, "\n", 1);
138
139	/* Restore old terminal settings and signals. */
140	if (memcmp(&term, &oterm, sizeof(term)) != 0) {
141		while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&
142		    errno == EINTR && !signo[SIGTTOU])
143			continue;
144	}
145	(void)_sigaction(SIGALRM, &savealrm, NULL);
146	(void)_sigaction(SIGHUP, &savehup, NULL);
147	(void)_sigaction(SIGINT, &saveint, NULL);
148	(void)_sigaction(SIGQUIT, &savequit, NULL);
149	(void)_sigaction(SIGPIPE, &savepipe, NULL);
150	(void)_sigaction(SIGTERM, &saveterm, NULL);
151	(void)_sigaction(SIGTSTP, &savetstp, NULL);
152	(void)_sigaction(SIGTTIN, &savettin, NULL);
153	(void)_sigaction(SIGTTOU, &savettou, NULL);
154	if (input != STDIN_FILENO)
155		(void)_close(input);
156
157	/*
158	 * If we were interrupted by a signal, resend it to ourselves
159	 * now that we have restored the signal handlers.
160	 */
161	for (i = 0; i < NSIG; i++) {
162		if (signo[i]) {
163			kill(getpid(), i);
164			switch (i) {
165			case SIGTSTP:
166			case SIGTTIN:
167			case SIGTTOU:
168				need_restart = 1;
169			}
170		}
171	}
172	if (need_restart)
173		goto restart;
174
175	if (save_errno)
176		errno = save_errno;
177	return(nr == -1 ? NULL : buf);
178}
179
180char *
181getpass(const char *prompt)
182{
183	static char buf[_PASSWORD_LEN + 1];
184
185	if (readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF) == NULL)
186		buf[0] = '\0';
187	return(buf);
188}
189
190static void handler(int s)
191{
192
193	signo[s] = 1;
194}
195