1 /* $NetBSD: getpass.c,v 1.22 2012/04/13 14:16:27 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2012 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include <sys/cdefs.h> 32 #if defined(LIBC_SCCS) && !defined(lint) 33 __RCSID("$NetBSD: getpass.c,v 1.22 2012/04/13 14:16:27 christos Exp $"); 34 #endif /* LIBC_SCCS and not lint */ 35 36 #include "namespace.h" 37 38 #include <assert.h> 39 #ifdef TEST 40 #include <stdio.h> 41 #endif 42 #include <errno.h> 43 #include <ctype.h> 44 #include <signal.h> 45 #include <string.h> 46 #include <paths.h> 47 #include <stdbool.h> 48 #include <stdlib.h> 49 #include <termios.h> 50 #include <unistd.h> 51 #include <fcntl.h> 52 53 #ifdef __weak_alias 54 __weak_alias(getpassfd,_getpassfd) 55 __weak_alias(getpass_r,_getpass_r) 56 __weak_alias(getpass,_getpass) 57 #endif 58 59 /* 60 * Notes: 61 * - There is no getpass_r in POSIX 62 * - Historically EOF is documented to be treated as EOL, we provide a 63 * tunable for that GETPASS_FAIL_EOF to disable this. 64 * - Historically getpass ate extra characters silently, we provide 65 * a tunable for that GETPASS_BUF_LIMIT to disable this. 66 * - Historically getpass "worked" by echoing characters when turning 67 * off echo failed, we provide a tunable GETPASS_NEED_TTY to 68 * disable this. 69 * - Some implementations say that on interrupt the program shall 70 * receive an interrupt signal before the function returns. We 71 * send all the tty signals before we return, but we don't expect 72 * suspend to do something useful unless the caller calls us again. 73 * We also provide a tunable to disable signal delivery 74 * GETPASS_NO_SIGNAL. 75 * - GETPASS_NO_BEEP disables beeping. 76 * - GETPASS_ECHO_STAR will echo '*' for each character of the password 77 * - GETPASS_ECHO will echo the password (as pam likes it) 78 */ 79 char * 80 /*ARGSUSED*/ 81 getpassfd(const char *prompt, char *buf, size_t len, int fd[], int flags) 82 { 83 struct termios gt; 84 char c; 85 int sig; 86 bool lnext, havetty, allocated; 87 88 _DIAGASSERT(prompt != NULL); 89 90 sig = 0; 91 92 allocated = buf == NULL; 93 if (tcgetattr(fd[0], >) == -1) { 94 havetty = false; 95 if (flags & GETPASS_NEED_TTY) 96 goto out; 97 memset(>, -1, sizeof(gt)); 98 } else 99 havetty = true; 100 101 102 if (havetty) { 103 struct termios st = gt; 104 105 st.c_lflag &= ~(ECHO|ECHOK|ECHOE|ECHOKE|ECHOCTL|ISIG|ICANON); 106 st.c_cc[VMIN] = 1; 107 st.c_cc[VTIME] = 0; 108 if (tcsetattr(fd[0], TCSAFLUSH|TCSASOFT, &st) == -1) 109 goto out; 110 } 111 112 if (prompt != NULL) { 113 size_t plen = strlen(prompt); 114 (void)write(fd[1], prompt, plen); 115 } 116 117 if (allocated) { 118 len = 1024; 119 if ((buf = malloc(len)) == NULL) 120 goto restore; 121 } 122 123 c = '\1'; 124 lnext = false; 125 for (size_t l = 0; c != '\0'; ) { 126 if (read(fd[0], &c, 1) != 1) 127 goto restore; 128 129 #define beep() do \ 130 if (flags & GETPASS_NO_BEEP) \ 131 (void)write(fd[2], "\a", 1); \ 132 while (/*CONSTCOND*/ 0) 133 #define erase() (void)write(fd[1], "\b \b", 3) 134 135 #define C(a, b) (gt.c_cc[(a)] == _POSIX_VDISABLE ? (b) : gt.c_cc[(a)]) 136 137 if (lnext) { 138 lnext = false; 139 goto add; 140 } 141 142 /* Ignored */ 143 if (c == C(VREPRINT, CTRL('r')) || c == C(VSTART, CTRL('q')) || 144 c == C(VSTOP, CTRL('s')) || c == C(VSTATUS, CTRL('t')) || 145 c == C(VDISCARD, CTRL('o'))) 146 continue; 147 148 /* Literal next */ 149 if (c == C(VLNEXT, CTRL('v'))) { 150 lnext = true; 151 continue; 152 } 153 154 /* Line or word kill, treat as reset */ 155 if (c == C(VKILL, CTRL('u')) || c == C(VWERASE, CTRL('w'))) { 156 if (flags & (GETPASS_ECHO | GETPASS_ECHO_STAR)) { 157 while (l--) 158 erase(); 159 } 160 l = 0; 161 continue; 162 } 163 164 /* Character erase */ 165 if (c == C(VERASE, CTRL('h'))) { 166 if (l == 0) 167 beep(); 168 else { 169 l--; 170 if (flags & (GETPASS_ECHO | GETPASS_ECHO_STAR)) 171 erase(); 172 } 173 continue; 174 } 175 176 /* tty signal characters */ 177 if (c == C(VINTR, CTRL('c'))) { 178 sig = SIGINT; 179 goto out; 180 } 181 if (c == C(VQUIT, CTRL('\\'))) { 182 sig = SIGQUIT; 183 goto out; 184 } 185 if (c == C(VSUSP, CTRL('z')) || c == C(VDSUSP, CTRL('y'))) { 186 sig = SIGTSTP; 187 goto out; 188 } 189 190 /* EOF */ 191 if (c == C(VEOF, CTRL('d'))) { 192 if (flags & GETPASS_FAIL_EOF) { 193 errno = ENODATA; 194 goto out; 195 } else { 196 c = '\0'; 197 goto add; 198 } 199 } 200 201 /* End of line */ 202 if (c == C(VEOL, CTRL('j')) || c == C(VEOL2, CTRL('l'))) 203 c = '\0'; 204 add: 205 if (l >= len) { 206 if (allocated) { 207 size_t nlen = len + 1024; 208 char *nbuf = realloc(buf, nlen); 209 if (nbuf == NULL) 210 goto restore; 211 buf = nbuf; 212 len = nlen; 213 } else { 214 if (flags & GETPASS_BUF_LIMIT) { 215 beep(); 216 continue; 217 } 218 if (c == '\0' && l > 0) 219 l--; 220 else 221 continue; 222 } 223 } 224 buf[l++] = c; 225 if (c) { 226 if (flags & GETPASS_ECHO_STAR) 227 (void)write(fd[1], "*", 1); 228 else if (flags & GETPASS_ECHO) 229 (void)write(fd[1], isprint((unsigned char)c) ? 230 &c : "?", 1); 231 } 232 } 233 234 if (havetty) 235 (void)tcsetattr(fd[0], TCSAFLUSH|TCSASOFT, >); 236 return buf; 237 restore: 238 if (havetty) { 239 c = errno; 240 (void)tcsetattr(fd[0], TCSAFLUSH|TCSASOFT, >); 241 errno = c; 242 } 243 out: 244 if (sig) { 245 if ((flags & GETPASS_NO_SIGNAL) == 0) 246 (void)raise(sig); 247 errno = EINTR; 248 } 249 memset(buf, 0, len); 250 if (allocated) 251 free(buf); 252 return NULL; 253 } 254 255 char * 256 getpass_r(const char *prompt, char *buf, size_t len) 257 { 258 bool opentty; 259 int fd[3]; 260 char *rv; 261 262 /* 263 * Try to use /dev/tty if possible; otherwise read from stdin and 264 * write to stderr. 265 */ 266 if ((fd[0] = fd[1] = fd[2] = open(_PATH_TTY, O_RDWR)) == -1) { 267 opentty = false; 268 fd[0] = STDIN_FILENO; 269 fd[1] = fd[2] = STDERR_FILENO; 270 } else 271 opentty = true; 272 273 rv = getpassfd(prompt, buf, len, fd, 0); 274 275 if (opentty) { 276 int serrno = errno; 277 (void)close(fd[0]); 278 errno = serrno; 279 } 280 return rv; 281 } 282 283 char * 284 getpass(const char *prompt) 285 { 286 static char e[] = ""; 287 static char *buf; 288 static long bufsiz; 289 char *rv; 290 291 /* 292 * Strictly speaking we could double allocate here, if we get 293 * called at the same time, but this function is not re-entrant 294 * anyway and it is not supposed to work if called concurrently. 295 */ 296 if (buf == NULL) { 297 if ((bufsiz = sysconf(_SC_PASS_MAX)) == -1) 298 return e; 299 if ((buf = malloc((size_t)bufsiz)) == NULL) 300 return e; 301 } 302 303 if ((rv = getpass_r(prompt, buf, (size_t)bufsiz)) == NULL) 304 return e; 305 306 return rv; 307 } 308 309 #ifdef TEST 310 int 311 main(int argc, char *argv[]) 312 { 313 char buf[28]; 314 int fd[3] = { 0, 1, 2 }; 315 printf("[%s]\n", getpassfd("foo>", buf, sizeof(buf), fd, 316 GETPASS_ECHO_STAR)); 317 return 0; 318 } 319 #endif 320