readpassphrase.c (5310 bytes)
1 /* $OpenBSD: readpassphrase.c,v 1.25 2015/09/14 10:45:27 guenther 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 #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 34 #include "readpassphrase.h" 35 36 #ifdef TCSASOFT 37 #define _T_FLUSH (TCSAFLUSH|TCSASOFT) 38 #else 39 #define _T_FLUSH (TCSAFLUSH) 40 #endif 41 42 static volatile sig_atomic_t signo[_NSIG]; 43 44 static void handler(int); 45 46 char * 47 readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags) 48 { 49 ssize_t nr; 50 int input, output, save_errno, i, need_restart; 51 char ch, *p, *end; 52 struct termios term, oterm; 53 struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm; 54 struct sigaction savetstp, savettin, savettou, savepipe; 55 56 /* I suppose we could alloc on demand in this case (XXX). */ 57 if (bufsiz == 0) { 58 errno = EINVAL; 59 return(NULL); 60 } 61 62 restart: 63 for (i = 0; i < _NSIG; i++) 64 signo[i] = 0; 65 nr = -1; 66 save_errno = 0; 67 need_restart = 0; 68 /* 69 * Read and write to /dev/tty if available. If not, read from 70 * stdin and write to stderr unless a tty is required. 71 */ 72 if ((flags & RPP_STDIN) || 73 (input = output = open(_PATH_TTY, O_RDWR)) == -1) { 74 if (flags & RPP_REQUIRE_TTY) { 75 errno = ENOTTY; 76 return(NULL); 77 } 78 input = STDIN_FILENO; 79 output = STDERR_FILENO; 80 } 81 82 /* 83 * Turn off echo if possible. 84 * If we are using a tty but are not the foreground pgrp this will 85 * generate SIGTTOU, so do it *before* installing the signal handlers. 86 */ 87 if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) { 88 memcpy(&term, &oterm, sizeof(term)); 89 if (!(flags & RPP_ECHO_ON)) 90 term.c_lflag &= ~(ECHO | ECHONL); 91 #ifdef VSTATUS 92 if (term.c_cc[VSTATUS] != _POSIX_VDISABLE) 93 term.c_cc[VSTATUS] = _POSIX_VDISABLE; 94 #endif 95 (void)tcsetattr(input, _T_FLUSH, &term); 96 } else { 97 memset(&term, 0, sizeof(term)); 98 term.c_lflag |= ECHO; 99 memset(&oterm, 0, sizeof(oterm)); 100 oterm.c_lflag |= ECHO; 101 } 102 103 /* 104 * Catch signals that would otherwise cause the user to end 105 * up with echo turned off in the shell. Don't worry about 106 * things like SIGXCPU and SIGVTALRM for now. 107 */ 108 sigemptyset(&sa.sa_mask); 109 sa.sa_flags = 0; /* don't restart system calls */ 110 sa.sa_handler = handler; 111 (void)sigaction(SIGALRM, &sa, &savealrm); 112 (void)sigaction(SIGHUP, &sa, &savehup); 113 (void)sigaction(SIGINT, &sa, &saveint); 114 (void)sigaction(SIGPIPE, &sa, &savepipe); 115 (void)sigaction(SIGQUIT, &sa, &savequit); 116 (void)sigaction(SIGTERM, &sa, &saveterm); 117 (void)sigaction(SIGTSTP, &sa, &savetstp); 118 (void)sigaction(SIGTTIN, &sa, &savettin); 119 (void)sigaction(SIGTTOU, &sa, &savettou); 120 121 if (!(flags & RPP_STDIN)) 122 (void)write(output, prompt, strlen(prompt)); 123 end = buf + bufsiz - 1; 124 p = buf; 125 while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') { 126 if (p < end) { 127 if ((flags & RPP_SEVENBIT)) 128 ch &= 0x7f; 129 if (isalpha((unsigned char)ch)) { 130 if ((flags & RPP_FORCELOWER)) 131 ch = (char)tolower((unsigned char)ch); 132 if ((flags & RPP_FORCEUPPER)) 133 ch = (char)toupper((unsigned char)ch); 134 } 135 *p++ = ch; 136 } 137 } 138 *p = '\0'; 139 save_errno = errno; 140 if (!(term.c_lflag & ECHO)) 141 (void)write(output, "\n", 1); 142 143 /* Restore old terminal settings and signals. */ 144 if (memcmp(&term, &oterm, sizeof(term)) != 0) { 145 while (tcsetattr(input, _T_FLUSH, &oterm) == -1 && 146 errno == EINTR && !signo[SIGTTOU]) 147 continue; 148 } 149 (void)sigaction(SIGALRM, &savealrm, NULL); 150 (void)sigaction(SIGHUP, &savehup, NULL); 151 (void)sigaction(SIGINT, &saveint, NULL); 152 (void)sigaction(SIGQUIT, &savequit, NULL); 153 (void)sigaction(SIGPIPE, &savepipe, NULL); 154 (void)sigaction(SIGTERM, &saveterm, NULL); 155 (void)sigaction(SIGTSTP, &savetstp, NULL); 156 (void)sigaction(SIGTTIN, &savettin, NULL); 157 (void)sigaction(SIGTTOU, &savettou, NULL); 158 if (input != STDIN_FILENO) 159 (void)close(input); 160 161 /* 162 * If we were interrupted by a signal, resend it to ourselves 163 * now that we have restored the signal handlers. 164 */ 165 for (i = 0; i < _NSIG; i++) { 166 if (signo[i]) { 167 kill(getpid(), i); 168 switch (i) { 169 case SIGTSTP: 170 case SIGTTIN: 171 case SIGTTOU: 172 need_restart = 1; 173 } 174 } 175 } 176 if (need_restart) 177 goto restart; 178 179 if (save_errno) 180 errno = save_errno; 181 return(nr == -1 ? NULL : buf); 182 } 183 184 static void handler(int s) 185 { 186 signo[s] = 1; 187 }