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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 #ifndef _NSIG
50 # ifdef NSIG
51 #  define _NSIG NSIG
52 # else
53 #  define _NSIG 128
54 # endif
55 #endif
56 
57 static volatile sig_atomic_t signo[_NSIG];
58 
59 static void handler(int);
60 
61 char *
readpassphrase(const char * prompt,char * buf,size_t bufsiz,int flags)62 readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags)
63 {
64 	ssize_t nr;
65 	int input, output, save_errno, i, need_restart;
66 	char ch, *p, *end;
67 	struct termios term, oterm;
68 	struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm;
69 	struct sigaction savetstp, savettin, savettou, savepipe;
70 
71 	/* I suppose we could alloc on demand in this case (XXX). */
72 	if (bufsiz == 0) {
73 		errno = EINVAL;
74 		return(NULL);
75 	}
76 
77 restart:
78 	for (i = 0; i < _NSIG; i++)
79 		signo[i] = 0;
80 	nr = -1;
81 	save_errno = 0;
82 	need_restart = 0;
83 	/*
84 	 * Read and write to /dev/tty if available.  If not, read from
85 	 * stdin and write to stderr unless a tty is required.
86 	 */
87 	if ((flags & RPP_STDIN) ||
88 	    (input = output = open(_PATH_TTY, O_RDWR)) == -1) {
89 		if (flags & RPP_REQUIRE_TTY) {
90 			errno = ENOTTY;
91 			return(NULL);
92 		}
93 		input = STDIN_FILENO;
94 		output = STDERR_FILENO;
95 	}
96 
97 	/*
98 	 * Turn off echo if possible.
99 	 * If we are using a tty but are not the foreground pgrp this will
100 	 * generate SIGTTOU, so do it *before* installing the signal handlers.
101 	 */
102 	if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) {
103 		memcpy(&term, &oterm, sizeof(term));
104 		if (!(flags & RPP_ECHO_ON))
105 			term.c_lflag &= ~(ECHO | ECHONL);
106 #ifdef VSTATUS
107 		if (term.c_cc[VSTATUS] != _POSIX_VDISABLE)
108 			term.c_cc[VSTATUS] = _POSIX_VDISABLE;
109 #endif
110 		(void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term);
111 	} else {
112 		memset(&term, 0, sizeof(term));
113 		term.c_lflag |= ECHO;
114 		memset(&oterm, 0, sizeof(oterm));
115 		oterm.c_lflag |= ECHO;
116 	}
117 
118 	/*
119 	 * Catch signals that would otherwise cause the user to end
120 	 * up with echo turned off in the shell.  Don't worry about
121 	 * things like SIGXCPU and SIGVTALRM for now.
122 	 */
123 	sigemptyset(&sa.sa_mask);
124 	sa.sa_flags = 0;		/* don't restart system calls */
125 	sa.sa_handler = handler;
126 	(void)sigaction(SIGALRM, &sa, &savealrm);
127 	(void)sigaction(SIGHUP, &sa, &savehup);
128 	(void)sigaction(SIGINT, &sa, &saveint);
129 	(void)sigaction(SIGPIPE, &sa, &savepipe);
130 	(void)sigaction(SIGQUIT, &sa, &savequit);
131 	(void)sigaction(SIGTERM, &sa, &saveterm);
132 	(void)sigaction(SIGTSTP, &sa, &savetstp);
133 	(void)sigaction(SIGTTIN, &sa, &savettin);
134 	(void)sigaction(SIGTTOU, &sa, &savettou);
135 
136 	if (!(flags & RPP_STDIN))
137 		(void)write(output, prompt, strlen(prompt));
138 	end = buf + bufsiz - 1;
139 	p = buf;
140 	while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') {
141 		if (p < end) {
142 			if ((flags & RPP_SEVENBIT))
143 				ch &= 0x7f;
144 			if (isalpha((unsigned char)ch)) {
145 				if ((flags & RPP_FORCELOWER))
146 					ch = (char)tolower((unsigned char)ch);
147 				if ((flags & RPP_FORCEUPPER))
148 					ch = (char)toupper((unsigned char)ch);
149 			}
150 			*p++ = ch;
151 		}
152 	}
153 	*p = '\0';
154 	save_errno = errno;
155 	if (!(term.c_lflag & ECHO))
156 		(void)write(output, "\n", 1);
157 
158 	/* Restore old terminal settings and signals. */
159 	if (memcmp(&term, &oterm, sizeof(term)) != 0) {
160 		const int sigttou = signo[SIGTTOU];
161 
162 		/* Ignore SIGTTOU generated when we are not the fg pgrp. */
163 		while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 &&
164 		    errno == EINTR && !signo[SIGTTOU])
165 			continue;
166 		signo[SIGTTOU] = sigttou;
167 	}
168 	(void)sigaction(SIGALRM, &savealrm, NULL);
169 	(void)sigaction(SIGHUP, &savehup, NULL);
170 	(void)sigaction(SIGINT, &saveint, NULL);
171 	(void)sigaction(SIGQUIT, &savequit, NULL);
172 	(void)sigaction(SIGPIPE, &savepipe, NULL);
173 	(void)sigaction(SIGTERM, &saveterm, NULL);
174 	(void)sigaction(SIGTSTP, &savetstp, NULL);
175 	(void)sigaction(SIGTTIN, &savettin, NULL);
176 	(void)sigaction(SIGTTOU, &savettou, NULL);
177 	if (input != STDIN_FILENO)
178 		(void)close(input);
179 
180 	/*
181 	 * If we were interrupted by a signal, resend it to ourselves
182 	 * now that we have restored the signal handlers.
183 	 */
184 	for (i = 0; i < _NSIG; i++) {
185 		if (signo[i]) {
186 			kill(getpid(), i);
187 			switch (i) {
188 			case SIGTSTP:
189 			case SIGTTIN:
190 			case SIGTTOU:
191 				need_restart = 1;
192 			}
193 		}
194 	}
195 	if (need_restart)
196 		goto restart;
197 
198 	if (save_errno)
199 		errno = save_errno;
200 	return(nr == -1 ? NULL : buf);
201 }
202 DEF_WEAK(readpassphrase);
203 
204 #if 0
205 char *
206 getpass(const char *prompt)
207 {
208 	static char buf[_PASSWORD_LEN + 1];
209 
210 	return(readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF));
211 }
212 #endif
213 
handler(int s)214 static void handler(int s)
215 {
216 
217 	signo[s] = 1;
218 }
219 #endif /* HAVE_READPASSPHRASE */
220