1/*	$OpenBSD: readpassphrase.c,v 1.27 2019/01/25 00:19:25 millert Exp $	*/
2
3/*
4 * Copyright (c) 2000-2002, 2007, 2010
5 *	Todd C. Miller <millert@openbsd.org>
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 <ctype.h>
25#include <errno.h>
26#include <fcntl.h>
27#include <paths.h>
28#include <pwd.h>
29#include <signal.h>
30#include <string.h>
31#include <termios.h>
32#include <unistd.h>
33#include <readpassphrase.h>
34
35static volatile sig_atomic_t signo[_NSIG];
36
37static void handler(int);
38
39char *
40readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
41{
42	ssize_t nr;
43	int input, output, save_errno, i, need_restart;
44	char ch, *p, *end;
45	struct termios term, oterm;
46	struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;
47	struct sigaction savetstp, savettin, savettou, savepipe;
48
49	/* I suppose we could alloc on demand in this case (XXX). */
50	if (bufsiz == 0) {
51		errno = EINVAL;
52		return(NULL);
53	}
54
55restart:
56	for (i = 0; i < _NSIG; i++)
57		signo[i] = 0;
58	nr = -1;
59	save_errno = 0;
60	need_restart = 0;
61	/*
62	 * Read and write to /dev/tty if available.  If not, read from
63	 * stdin and write to stderr unless a tty is required.
64	 */
65	if ((flags & RPP_STDIN) ||
66	    (input = output = open(_PATH_TTY, O_RDWR)) == -1) {
67		if (flags & RPP_REQUIRE_TTY) {
68			errno = ENOTTY;
69			return(NULL);
70		}
71		input = STDIN_FILENO;
72		output = STDERR_FILENO;
73	}
74
75	/*
76	 * Turn off echo if possible.
77	 * If we are using a tty but are not the foreground pgrp this will
78	 * generate SIGTTOU, so do it *before* installing the signal handlers.
79	 */
80	if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) {
81		memcpy(&term, &oterm, sizeof(term));
82		if (!(flags & RPP_ECHO_ON))
83			term.c_lflag &= ~(ECHO | ECHONL);
84		if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)
85			term.c_cc[VSTATUS] = _POSIX_VDISABLE;
86		(void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);
87	} else {
88		memset(&term, 0, sizeof(term));
89		term.c_lflag |= ECHO;
90		memset(&oterm, 0, sizeof(oterm));
91		oterm.c_lflag |= ECHO;
92	}
93
94	/*
95	 * Catch signals that would otherwise cause the user to end
96	 * up with echo turned off in the shell.  Don't worry about
97	 * things like SIGXCPU and SIGVTALRM for now.
98	 */
99	sigemptyset(&sa.sa_mask);
100	sa.sa_flags = 0;		/* don't restart system calls */
101	sa.sa_handler = handler;
102	(void)sigaction(SIGALRM, &sa, &savealrm);
103	(void)sigaction(SIGHUP, &sa, &savehup);
104	(void)sigaction(SIGINT, &sa, &saveint);
105	(void)sigaction(SIGPIPE, &sa, &savepipe);
106	(void)sigaction(SIGQUIT, &sa, &savequit);
107	(void)sigaction(SIGTERM, &sa, &saveterm);
108	(void)sigaction(SIGTSTP, &sa, &savetstp);
109	(void)sigaction(SIGTTIN, &sa, &savettin);
110	(void)sigaction(SIGTTOU, &sa, &savettou);
111
112	if (!(flags & RPP_STDIN))
113		(void)write(output, prompt, strlen(prompt));
114	end = buf + bufsiz - 1;
115	p = buf;
116	while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
117		if (p < end) {
118			if ((flags & RPP_SEVENBIT))
119				ch &= 0x7f;
120			if (isalpha((unsigned char)ch)) {
121				if ((flags & RPP_FORCELOWER))
122					ch = (char)tolower((unsigned char)ch);
123				if ((flags & RPP_FORCEUPPER))
124					ch = (char)toupper((unsigned char)ch);
125			}
126			*p++ = ch;
127		}
128	}
129	*p = '\0';
130	save_errno = errno;
131	if (!(term.c_lflag & ECHO))
132		(void)write(output, "\n", 1);
133
134	/* Restore old terminal settings and signals. */
135	if (memcmp(&term, &oterm, sizeof(term)) != 0) {
136		const int sigttou = signo[SIGTTOU];
137
138		/* Ignore SIGTTOU generated when we are not the fg pgrp. */
139		while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&
140		    errno == EINTR && !signo[SIGTTOU])
141			continue;
142		signo[SIGTTOU] = sigttou;
143	}
144	(void)sigaction(SIGALRM, &savealrm, NULL);
145	(void)sigaction(SIGHUP, &savehup, NULL);
146	(void)sigaction(SIGINT, &saveint, NULL);
147	(void)sigaction(SIGQUIT, &savequit, NULL);
148	(void)sigaction(SIGPIPE, &savepipe, NULL);
149	(void)sigaction(SIGTERM, &saveterm, NULL);
150	(void)sigaction(SIGTSTP, &savetstp, NULL);
151	(void)sigaction(SIGTTIN, &savettin, NULL);
152	(void)sigaction(SIGTTOU, &savettou, NULL);
153	if (input != STDIN_FILENO)
154		(void)close(input);
155
156	/*
157	 * If we were interrupted by a signal, resend it to ourselves
158	 * now that we have restored the signal handlers.
159	 */
160	for (i = 0; i < _NSIG; i++) {
161		if (signo[i]) {
162			kill(getpid(), i);
163			switch (i) {
164			case SIGTSTP:
165			case SIGTTIN:
166			case SIGTTOU:
167				need_restart = 1;
168			}
169		}
170	}
171	if (need_restart)
172		goto restart;
173
174	if (save_errno)
175		errno = save_errno;
176	return(nr == -1 ? NULL : buf);
177}
178DEF_WEAK(readpassphrase);
179
180char *
181getpass(const char *prompt)
182{
183	static char buf[_PASSWORD_LEN + 1];
184
185	return(readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF));
186}
187
188static void handler(int s)
189{
190
191	signo[s] = 1;
192}
193