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
35 static volatile sig_atomic_t signo[_NSIG];
36
37 static void handler(int);
38
39 char *
readpassphrase(const char * prompt,char * buf,size_t bufsiz,int flags)40 readpassphrase(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
55 restart:
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 }
178 DEF_WEAK(readpassphrase);
179
180 char *
getpass(const char * prompt)181 getpass(const char *prompt)
182 {
183 static char buf[_PASSWORD_LEN + 1];
184
185 return(readpassphrase(prompt, buf, sizeof(buf), RPP_ECHO_OFF));
186 }
187
handler(int s)188 static void handler(int s)
189 {
190
191 signo[s] = 1;
192 }
193