readpassphrase.c revision 302408 
1/*	$OpenBSD: readpassphrase.c,v 1.24 2013/11/24 23:51:29 deraadt 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: stable/11/lib/libc/gen/readpassphrase.c 294691 2016-01-24 22:20:13Z sobomax $");
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#include "libc_private.h"
40
41static volatile sig_atomic_t signo[NSIG];
42
43static void handler(int);
44
45char *
46readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
47{
48	ssize_t nr;
49	int input, output, save_errno, i, need_restart, input_is_tty;
50	char ch, *p, *end;
51	struct termios term, oterm;
52	struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;
53	struct sigaction savetstp, savettin, savettou, savepipe;
54
55	/* I suppose we could alloc on demand in this case (XXX). */
56	if (bufsiz == 0) {
57		errno = EINVAL;
58		return(NULL);
59	}
60
61restart:
62	for (i = 0; i < NSIG; i++)
63		signo[i] = 0;
64	nr = -1;
65	save_errno = 0;
66	need_restart = 0;
67	/*
68	 * Read and write to /dev/tty if available.  If not, read from
69	 * stdin and write to stderr unless a tty is required.
70	 */
71	input_is_tty = 0;
72	if (!(flags & RPP_STDIN)) {
73        	input = output = _open(_PATH_TTY, O_RDWR | O_CLOEXEC);
74		if (input == -1) {
75			if (flags & RPP_REQUIRE_TTY) {
76				errno = ENOTTY;
77				return(NULL);
78			}
79			input = STDIN_FILENO;
80			output = STDERR_FILENO;
81		} else {
82			input_is_tty = 1;
83		}
84	} else {
85		input = STDIN_FILENO;
86		output = STDERR_FILENO;
87	}
88
89	/*
90	 * Turn off echo if possible.
91	 * If we are using a tty but are not the foreground pgrp this will
92	 * generate SIGTTOU, so do it *before* installing the signal handlers.
93	 */
94	if (input_is_tty && tcgetattr(input, &oterm) == 0) {
95		memcpy(&term, &oterm, sizeof(term));
96		if (!(flags & RPP_ECHO_ON))
97			term.c_lflag &= ~(ECHO | ECHONL);
98		if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)
99			term.c_cc[VSTATUS] = _POSIX_VDISABLE;
100		(void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);
101	} else {
102		memset(&term, 0, sizeof(term));
103		term.c_lflag |= ECHO;
104		memset(&oterm, 0, sizeof(oterm));
105		oterm.c_lflag |= ECHO;
106	}
107
108	/*
109	 * Catch signals that would otherwise cause the user to end
110	 * up with echo turned off in the shell.  Don't worry about
111	 * things like SIGXCPU and SIGVTALRM for now.
112	 */
113	sigemptyset(&sa.sa_mask);
114	sa.sa_flags = 0;		/* don't restart system calls */
115	sa.sa_handler = handler;
116	(void)__libc_sigaction(SIGALRM, &sa, &savealrm);
117	(void)__libc_sigaction(SIGHUP, &sa, &savehup);
118	(void)__libc_sigaction(SIGINT, &sa, &saveint);
119	(void)__libc_sigaction(SIGPIPE, &sa, &savepipe);
120	(void)__libc_sigaction(SIGQUIT, &sa, &savequit);
121	(void)__libc_sigaction(SIGTERM, &sa, &saveterm);
122	(void)__libc_sigaction(SIGTSTP, &sa, &savetstp);
123	(void)__libc_sigaction(SIGTTIN, &sa, &savettin);
124	(void)__libc_sigaction(SIGTTOU, &sa, &savettou);
125
126	if (!(flags & RPP_STDIN))
127		(void)_write(output, prompt, strlen(prompt));
128	end = buf + bufsiz - 1;
129	p = buf;
130	while ((nr = _read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
131		if (p < end) {
132			if ((flags & RPP_SEVENBIT))
133				ch &= 0x7f;
134			if (isalpha((unsigned char)ch)) {
135				if ((flags & RPP_FORCELOWER))
136					ch = (char)tolower((unsigned char)ch);
137				if ((flags & RPP_FORCEUPPER))
138					ch = (char)toupper((unsigned char)ch);
139			}
140			*p++ = ch;
141		}
142	}
143	*p = '\0';
144	save_errno = errno;
145	if (!(term.c_lflag & ECHO))
146		(void)_write(output, "\n", 1);
147
148	/* Restore old terminal settings and signals. */
149	if (memcmp(&term, &oterm, sizeof(term)) != 0) {
150		while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&
151		    errno == EINTR && !signo[SIGTTOU])
152			continue;
153	}
154	(void)__libc_sigaction(SIGALRM, &savealrm, NULL);
155	(void)__libc_sigaction(SIGHUP, &savehup, NULL);
156	(void)__libc_sigaction(SIGINT, &saveint, NULL);
157	(void)__libc_sigaction(SIGQUIT, &savequit, NULL);
158	(void)__libc_sigaction(SIGPIPE, &savepipe, NULL);
159	(void)__libc_sigaction(SIGTERM, &saveterm, NULL);
160	(void)__libc_sigaction(SIGTSTP, &savetstp, NULL);
161	(void)__libc_sigaction(SIGTTIN, &savettin, NULL);
162	(void)__libc_sigaction(SIGTTOU, &savettou, NULL);
163	if (input_is_tty)
164		(void)_close(input);
165
166	/*
167	 * If we were interrupted by a signal, resend it to ourselves
168	 * now that we have restored the signal handlers.
169	 */
170	for (i = 0; i < NSIG; i++) {
171		if (signo[i]) {
172			kill(getpid(), i);
173			switch (i) {
174			case SIGTSTP:
175			case SIGTTIN:
176			case SIGTTOU:
177				need_restart = 1;
178			}
179		}
180	}
181	if (need_restart)
182		goto restart;
183
184	if (save_errno)
185		errno = save_errno;
186	return(nr == -1 ? NULL : buf);
187}
188
189char *
190getpass(const char *prompt)
191{
192	static char buf[_PASSWORD_LEN + 1];
193
194	if (readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF) == NULL)
195		buf[0] = '\0';
196	return(buf);
197}
198
199static void handler(int s)
200{
201
202	signo[s] = 1;
203}
204