lib/libc/gen/getpass.c

   1 /*      $NetBSD: getpass.c,v 1.27 2012/05/26 19:34:16 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 1.27 2012/05/26 19:34:16 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 #include <poll.h>
  53
  54 #ifdef __weak_alias
  55 __weak_alias(getpassfd,_getpassfd)
  56 __weak_alias(getpass_r,_getpass_r)
  57 __weak_alias(getpass,_getpass)
  58 #endif
  59
  60 /*
  61  * Notes:
  62  *      - There is no getpass_r in POSIX
  63  *      - Historically EOF is documented to be treated as EOL, we provide a
  64  *        tunable for that GETPASS_FAIL_EOF to disable this.
  65  *      - Historically getpass ate extra characters silently, we provide
  66  *        a tunable for that GETPASS_BUF_LIMIT to disable this.
  67  *      - Historically getpass "worked" by echoing characters when turning
  68  *        off echo failed, we provide a tunable GETPASS_NEED_TTY to
  69  *        disable this.
  70  *      - Some implementations say that on interrupt the program shall
  71  *        receive an interrupt signal before the function returns. We
  72  *        send all the tty signals before we return, but we don't expect
  73  *        suspend to do something useful unless the caller calls us again.
  74  *        We also provide a tunable to disable signal delivery
  75  *        GETPASS_NO_SIGNAL.
  76  *      - GETPASS_NO_BEEP disables beeping.
  77  *      - GETPASS_ECHO_STAR will echo '*' for each character of the password
  78  *      - GETPASS_ECHO will echo the password (as pam likes it)
  79  *      - GETPASS_7BIT strips the 8th bit
  80  *      - GETPASS_FORCE_UPPER forces to uppercase
  81  *      - GETPASS_FORCE_LOWER forces to uppercase
  82  *      - GETPASS_ECHO_NL echo's a new line on success if echo was off.
  83  */
  84 char *
  85 /*ARGSUSED*/
  86 getpassfd(const char *prompt, char *buf, size_t len, int *fd, int flags,
  87     int tout)
  88 {
  89         struct termios gt;
  90         char c;
  91         int sig;
  92         bool lnext, havetty, allocated, opentty, good;
  93         int fdc[3];
  94
  95         _DIAGASSERT(prompt != NULL);
  96
  97         if (buf != NULL && len == 0) {
  98                 errno = EINVAL;
  99                 return NULL;
 100         }
 101
 102         good = false;
 103         opentty = false;
 104         if (fd == NULL) {
 105                 /*
 106                  * Try to use /dev/tty if possible; otherwise read from stdin
 107                  * and write to stderr.
 108                  */
 109                 fd = fdc;
 110                 if ((fd[0] = fd[1] = fd[2] = open(_PATH_TTY, O_RDWR)) == -1) {
 111                         fd[0] = STDIN_FILENO;
 112                         fd[1] = fd[2] = STDERR_FILENO;
 113                 } else
 114                         opentty = true;
 115         }
 116
 117         sig = 0;
 118         allocated = buf == NULL;
 119         if (tcgetattr(fd[0], &gt) == -1) {
 120                 havetty = false;
 121                 if (flags & GETPASS_NEED_TTY)
 122                         goto out;
 123                 memset(&gt, -1, sizeof(gt));
 124         } else
 125                 havetty = true;
 126
 127         if (havetty) {
 128                 struct termios st = gt;
 129
 130                 st.c_lflag &= ~(ECHO|ECHOK|ECHOE|ECHOKE|ECHOCTL|ISIG|ICANON);
 131                 st.c_cc[VMIN] = 1;
 132                 st.c_cc[VTIME] = 0;
 133                 if (tcsetattr(fd[0], TCSAFLUSH|TCSASOFT, &st) == -1)
 134                         goto out;
 135         }
 136
 137         if (prompt != NULL) {
 138                 size_t plen = strlen(prompt);
 139                 (void)write(fd[1], prompt, plen);
 140         }
 141
 142         if (allocated) {
 143                 len = 1024;
 144                 if ((buf = malloc(len)) == NULL)
 145                         goto restore;
 146         }
 147
 148         c = '\1';
 149         lnext = false;
 150         for (size_t l = 0; c != '\0'; ) {
 151                 if (tout) {
 152                         struct pollfd pfd;
 153                         pfd.fd = fd[0];
 154                         pfd.events = POLLIN|POLLRDNORM;
 155                         pfd.revents = 0;
 156                         switch (poll(&pfd, 1, tout * 1000)) {
 157                         case 0:
 158                                 errno = ETIMEDOUT;
 159                                 /*FALLTHROUGH*/
 160                         case -1:
 161                                 goto restore;
 162                         default:
 163                                 break;
 164                         }
 165                 }
 166                 if (read(fd[0], &c, 1) != 1)
 167                         goto restore;
 168
 169 #define beep() \
 170         do \
 171                 if (flags & GETPASS_NO_BEEP) \
 172                         (void)write(fd[2], "\a", 1); \
 173         while (/*CONSTCOND*/ 0)
 174 #define erase() (void)write(fd[1], "\b \b", 3)
 175 /*
 176  * We test for both _POSIX_VDISABLE and NUL here because _POSIX_VDISABLE
 177  * propagation does not seem to be very consistent on multiple daemon hops
 178  * between different OS's. Perhaps we should not even bother with
 179  * _POSIX_VDISABLE and use ~0 and 0 directly.
 180  */
 181 #define C(a, b) ((gt.c_cc[(a)] == _POSIX_VDISABLE || gt.c_cc[(a)] == '\0') ? \
 182     (b) : gt.c_cc[(a)])
 183                 if (lnext) {
 184                         lnext = false;
 185                         goto add;
 186                 }
 187
 188                 /* Ignored */
 189                 if (c == C(VREPRINT, CTRL('r')) || c == C(VSTART, CTRL('q')) ||
 190                     c == C(VSTOP, CTRL('s')) || c == C(VSTATUS, CTRL('t')) ||
 191                     c == C(VDISCARD, CTRL('o')))
 192                         continue;
 193
 194                 /* Literal next */
 195                 if (c == C(VLNEXT, CTRL('v'))) {
 196                         lnext = true;
 197                         continue;
 198                 }
 199
 200                 /* Line or word kill, treat as reset */
 201                 if (c == C(VKILL, CTRL('u')) || c == C(VWERASE, CTRL('w'))) {
 202                         if (flags & (GETPASS_ECHO | GETPASS_ECHO_STAR)) {
 203                                 while (l--)
 204                                         erase();
 205                         }
 206                         l = 0;
 207                         continue;
 208                 }
 209
 210                 /* Character erase */
 211                 if (c == C(VERASE, CTRL('h'))) {
 212                         if (l == 0)
 213                                 beep();
 214                         else {
 215                                 l--;
 216                                 if (flags & (GETPASS_ECHO | GETPASS_ECHO_STAR))
 217                                         erase();
 218                         }
 219                         continue;
 220                 }
 221
 222                 /* tty signal characters */
 223                 if (c == C(VINTR, CTRL('c'))) {
 224                         sig = SIGINT;
 225                         goto out;
 226                 }
 227                 if (c == C(VQUIT, CTRL('\\'))) {
 228                         sig = SIGQUIT;
 229                         goto out;
 230                 }
 231                 if (c == C(VSUSP, CTRL('z')) || c == C(VDSUSP, CTRL('y'))) {
 232                         sig = SIGTSTP;
 233                         goto out;
 234                 }
 235
 236                 /* EOF */
 237                 if (c == C(VEOF, CTRL('d')))  {
 238                         if (flags & GETPASS_FAIL_EOF) {
 239                                 errno = ENODATA;
 240                                 goto out;
 241                         } else {
 242                                 c = '\0';
 243                                 goto add;
 244                         }
 245                 }
 246
 247                 /* End of line */
 248                 if (c == C(VEOL, CTRL('j')) || c == C(VEOL2, CTRL('l')))
 249                         c = '\0';
 250 add:
 251                 if (l >= len) {
 252                         if (allocated) {
 253                                 size_t nlen = len + 1024;
 254                                 char *nbuf = realloc(buf, nlen);
 255                                 if (nbuf == NULL)
 256                                         goto restore;
 257                                 buf = nbuf;
 258                                 len = nlen;
 259                         } else {
 260                                 if (flags & GETPASS_BUF_LIMIT) {
 261                                         beep();
 262                                         continue;
 263                                 }
 264                                 if (c == '\0' && l > 0)
 265                                         l--;
 266                                 else
 267                                         continue;
 268                         }
 269                 }
 270
 271                 if (flags & GETPASS_7BIT)
 272                         c &= 0x7f;
 273                 if ((flags & GETPASS_FORCE_LOWER) && isupper((unsigned char)c))
 274                         c = tolower((unsigned char)c);
 275                 if ((flags & GETPASS_FORCE_UPPER) && islower((unsigned char)c))
 276                         c = toupper((unsigned char)c);
 277
 278                 buf[l++] = c;
 279                 if (c) {
 280                         if (flags & GETPASS_ECHO_STAR)
 281                                 (void)write(fd[1], "*", 1);
 282                         else if (flags & GETPASS_ECHO)
 283                                 (void)write(fd[1], isprint((unsigned char)c) ?
 284                                     &c : "?", 1);
 285                 }
 286         }
 287         good = true;
 288
 289 restore:
 290         if (havetty) {
 291                 c = errno;
 292                 (void)tcsetattr(fd[0], TCSAFLUSH|TCSASOFT, &gt);
 293                 errno = c;
 294         }
 295 out:
 296         if (good && (flags & GETPASS_ECHO_NL))
 297                 (void)write(fd[1], "\n", 1);
 298
 299         if (opentty) {
 300                 c = errno;
 301                 (void)close(fd[0]);
 302                 errno = c;
 303         }
 304
 305         if (good)
 306                 return buf;
 307
 308         if (sig) {
 309                 if ((flags & GETPASS_NO_SIGNAL) == 0)
 310                         (void)raise(sig);
 311                 errno = EINTR;
 312         }
 313         memset(buf, 0, len);
 314         if (allocated)
 315                 free(buf);
 316         return NULL;
 317 }
 318
 319 char *
 320 getpass_r(const char *prompt, char *buf, size_t len)
 321 {
 322         return getpassfd(prompt, buf, len, NULL, GETPASS_ECHO_NL, 0);
 323 }
 324
 325 char *
 326 getpass(const char *prompt)
 327 {
 328         static char e[] = "";
 329         static char *buf;
 330         static long bufsiz;
 331         char *rv;
 332
 333         /*
 334          * Strictly speaking we could double allocate here, if we get
 335          * called at the same time, but this function is not re-entrant
 336          * anyway and it is not supposed to work if called concurrently.
 337          */
 338         if (buf == NULL) {
 339                 if ((bufsiz = sysconf(_SC_PASS_MAX)) == -1)
 340                         return e;
 341                 if ((buf = malloc((size_t)bufsiz)) == NULL)
 342                         return e;
 343         }
 344
 345         if ((rv = getpass_r(prompt, buf, (size_t)bufsiz)) == NULL)
 346                 return e;
 347
 348         return rv;
 349 }
 350
 351 #ifdef TEST
 352 int
 353 main(int argc, char *argv[])
 354 {
 355         char buf[28];
 356         printf("[%s]\n", getpassfd("foo>", buf, sizeof(buf), NULL,
 357             GETPASS_ECHO_STAR|GETPASS_ECHO_NL, 2));
 358         return 0;
 359 }
 360 #endif