1 /*	$OpenBSD: readpassphrase.c,v 1.26 2016/10/18 12:47:18 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 /* OPENBSD ORIGINAL: lib/libc/gen/readpassphrase.c */
25 
26 #include "includes.h"
27 
28 #ifndef HAVE_READPASSPHRASE
29 
30 #include <termios.h>
31 #include <signal.h>
32 #include <ctype.h>
33 #include <fcntl.h>
34 #include <readpassphrase.h>
35 #include <errno.h>
36 #include <string.h>
37 #include <unistd.h>
38 
39 #ifndef TCSASOFT
40 /* If we don't have TCSASOFT define it so that ORing it it below is a no-op. */
41 # define TCSASOFT 0
42 #endif
43 
44 /* SunOS 4.x which lacks _POSIX_VDISABLE, but has VDISABLE */
45 #if !defined(_POSIX_VDISABLE) && defined(VDISABLE)
46 #  define _POSIX_VDISABLE       VDISABLE
47 #endif
48 
49 static volatile sig_atomic_t signo[_NSIG];
50 
51 static void handler(int);
52 
53 char *
readpassphrase(const char * prompt,char * buf,size_t bufsiz,int flags)54 readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
55 {
56 	ssize_t nr;
57 	int input, output, save_errno, i, need_restart;
58 	char ch, *p, *end;
59 	struct termios term, oterm;
60 	struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;
61 	struct sigaction savetstp, savettin, savettou, savepipe;
62 
63 	/* I suppose we could alloc on demand in this case (XXX). */
64 	if (bufsiz == 0) {
65 		errno = EINVAL;
66 		return(NULL);
67 	}
68 
69 restart:
70 	for (i = 0; i < _NSIG; i++)
71 		signo[i] = 0;
72 	nr = -1;
73 	save_errno = 0;
74 	need_restart = 0;
75 	/*
76 	 * Read and write to /dev/tty if available.  If not, read from
77 	 * stdin and write to stderr unless a tty is required.
78 	 */
79 	if ((flags & RPP_STDIN) ||
80 	    (input = output = open(_PATH_TTY, O_RDWR)) == -1) {
81 		if (flags & RPP_REQUIRE_TTY) {
82 			errno = ENOTTY;
83 			return(NULL);
84 		}
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 != STDIN_FILENO && tcgetattr(input, &oterm) == 0) {
95 		memcpy(&term, &oterm, sizeof(term));
96 		if (!(flags & RPP_ECHO_ON))
97 			term.c_lflag &= ~(ECHO | ECHONL);
98 #ifdef VSTATUS
99 		if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)
100 			term.c_cc[VSTATUS] = _POSIX_VDISABLE;
101 #endif
102 		(void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);
103 	} else {
104 		memset(&term, 0, sizeof(term));
105 		term.c_lflag |= ECHO;
106 		memset(&oterm, 0, sizeof(oterm));
107 		oterm.c_lflag |= ECHO;
108 	}
109 
110 	/*
111 	 * Catch signals that would otherwise cause the user to end
112 	 * up with echo turned off in the shell.  Don't worry about
113 	 * things like SIGXCPU and SIGVTALRM for now.
114 	 */
115 	sigemptyset(&sa.sa_mask);
116 	sa.sa_flags = 0;		/* don't restart system calls */
117 	sa.sa_handler = handler;
118 	(void)sigaction(SIGALRM, &sa, &savealrm);
119 	(void)sigaction(SIGHUP, &sa, &savehup);
120 	(void)sigaction(SIGINT, &sa, &saveint);
121 	(void)sigaction(SIGPIPE, &sa, &savepipe);
122 	(void)sigaction(SIGQUIT, &sa, &savequit);
123 	(void)sigaction(SIGTERM, &sa, &saveterm);
124 	(void)sigaction(SIGTSTP, &sa, &savetstp);
125 	(void)sigaction(SIGTTIN, &sa, &savettin);
126 	(void)sigaction(SIGTTOU, &sa, &savettou);
127 
128 	if (!(flags & RPP_STDIN))
129 		(void)write(output, prompt, strlen(prompt));
130 	end = buf + bufsiz - 1;
131 	p = buf;
132 	while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
133 		if (p < end) {
134 			if ((flags & RPP_SEVENBIT))
135 				ch &= 0x7f;
136 			if (isalpha((unsigned char)ch)) {
137 				if ((flags & RPP_FORCELOWER))
138 					ch = (char)tolower((unsigned char)ch);
139 				if ((flags & RPP_FORCEUPPER))
140 					ch = (char)toupper((unsigned char)ch);
141 			}
142 			*p++ = ch;
143 		}
144 	}
145 	*p = '\0';
146 	save_errno = errno;
147 	if (!(term.c_lflag & ECHO))
148 		(void)write(output, "\n", 1);
149 
150 	/* Restore old terminal settings and signals. */
151 	if (memcmp(&term, &oterm, sizeof(term)) != 0) {
152 		const int sigttou = signo[SIGTTOU];
153 
154 		/* Ignore SIGTTOU generated when we are not the fg pgrp. */
155 		while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&
156 		    errno == EINTR && !signo[SIGTTOU])
157 			continue;
158 		signo[SIGTTOU] = sigttou;
159 	}
160 	(void)sigaction(SIGALRM, &savealrm, NULL);
161 	(void)sigaction(SIGHUP, &savehup, NULL);
162 	(void)sigaction(SIGINT, &saveint, NULL);
163 	(void)sigaction(SIGQUIT, &savequit, NULL);
164 	(void)sigaction(SIGPIPE, &savepipe, NULL);
165 	(void)sigaction(SIGTERM, &saveterm, NULL);
166 	(void)sigaction(SIGTSTP, &savetstp, NULL);
167 	(void)sigaction(SIGTTIN, &savettin, NULL);
168 	(void)sigaction(SIGTTOU, &savettou, NULL);
169 	if (input != STDIN_FILENO)
170 		(void)close(input);
171 
172 	/*
173 	 * If we were interrupted by a signal, resend it to ourselves
174 	 * now that we have restored the signal handlers.
175 	 */
176 	for (i = 0; i < _NSIG; i++) {
177 		if (signo[i]) {
178 			kill(getpid(), i);
179 			switch (i) {
180 			case SIGTSTP:
181 			case SIGTTIN:
182 			case SIGTTOU:
183 				need_restart = 1;
184 			}
185 		}
186 	}
187 	if (need_restart)
188 		goto restart;
189 
190 	if (save_errno)
191 		errno = save_errno;
192 	return(nr == -1 ? NULL : buf);
193 }
194 DEF_WEAK(readpassphrase);
195 
196 #if 0
197 char *
198 getpass(const char *prompt)
199 {
200 	static char buf[_PASSWORD_LEN + 1];
201 
202 	return(readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF));
203 }
204 #endif
205 
handler(int s)206 static void handler(int s)
207 {
208 
209 	signo[s] = 1;
210 }
211 #endif /* HAVE_READPASSPHRASE */
212