readpassphrase.c (5424B)
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 #ifndef TCSASOFT 36 #define TCSASOFT 0 37 #endif 38 39 static volatile sig_atomic_t signo[_NSIG]; 40 41 static void handler(int); 42 43 char * 44 readpassphrase(const char *prompt, char *buf, size_t bufsiz, int flags) 45 { 46 ssize_t nr; 47 int input, output, save_errno, i, need_restart; 48 char ch, *p, *end; 49 struct termios term, oterm; 50 struct sigaction sa, savealrm, saveint, savehup, savequit, saveterm; 51 struct sigaction savetstp, savettin, savettou, savepipe; 52 53 /* I suppose we could alloc on demand in this case (XXX). */ 54 if (bufsiz == 0) { 55 errno = EINVAL; 56 return(NULL); 57 } 58 59 restart: 60 for (i = 0; i < _NSIG; i++) 61 signo[i] = 0; 62 nr = -1; 63 save_errno = 0; 64 need_restart = 0; 65 /* 66 * Read and write to /dev/tty if available. If not, read from 67 * stdin and write to stderr unless a tty is required. 68 */ 69 if ((flags & RPP_STDIN) || 70 (input = output = open(_PATH_TTY, O_RDWR)) == -1) { 71 if (flags & RPP_REQUIRE_TTY) { 72 errno = ENOTTY; 73 return(NULL); 74 } 75 input = STDIN_FILENO; 76 output = STDERR_FILENO; 77 } 78 79 /* 80 * Turn off echo if possible. 81 * If we are using a tty but are not the foreground pgrp this will 82 * generate SIGTTOU, so do it *before* installing the signal handlers. 83 */ 84 if (input != STDIN_FILENO && tcgetattr(input, &oterm) == 0) { 85 memcpy(&term, &oterm, sizeof(term)); 86 if (!(flags & RPP_ECHO_ON)) 87 term.c_lflag &= ~(ECHO | ECHONL); 88 #ifdef VSTATUS 89 if (term.c_cc[VSTATUS] != _POSIX_VDISABLE) 90 term.c_cc[VSTATUS] = _POSIX_VDISABLE; 91 #endif 92 (void)tcsetattr(input, TCSAFLUSH|TCSASOFT, &term); 93 } else { 94 memset(&term, 0, sizeof(term)); 95 term.c_lflag |= ECHO; 96 memset(&oterm, 0, sizeof(oterm)); 97 oterm.c_lflag |= ECHO; 98 } 99 100 /* 101 * Catch signals that would otherwise cause the user to end 102 * up with echo turned off in the shell. Don't worry about 103 * things like SIGXCPU and SIGVTALRM for now. 104 */ 105 sigemptyset(&sa.sa_mask); 106 sa.sa_flags = 0; /* don't restart system calls */ 107 sa.sa_handler = handler; 108 (void)sigaction(SIGALRM, &sa, &savealrm); 109 (void)sigaction(SIGHUP, &sa, &savehup); 110 (void)sigaction(SIGINT, &sa, &saveint); 111 (void)sigaction(SIGPIPE, &sa, &savepipe); 112 (void)sigaction(SIGQUIT, &sa, &savequit); 113 (void)sigaction(SIGTERM, &sa, &saveterm); 114 (void)sigaction(SIGTSTP, &sa, &savetstp); 115 (void)sigaction(SIGTTIN, &sa, &savettin); 116 (void)sigaction(SIGTTOU, &sa, &savettou); 117 118 if (!(flags & RPP_STDIN)) 119 (void)write(output, prompt, strlen(prompt)); 120 end = buf + bufsiz - 1; 121 p = buf; 122 while ((nr = read(input, &ch, 1)) == 1 && ch != '\n' && ch != '\r') { 123 if (p < end) { 124 if ((flags & RPP_SEVENBIT)) 125 ch &= 0x7f; 126 if (isalpha((unsigned char)ch)) { 127 if ((flags & RPP_FORCELOWER)) 128 ch = (char)tolower((unsigned char)ch); 129 if ((flags & RPP_FORCEUPPER)) 130 ch = (char)toupper((unsigned char)ch); 131 } 132 *p++ = ch; 133 } 134 } 135 *p = '\0'; 136 save_errno = errno; 137 if (!(term.c_lflag & ECHO)) 138 (void)write(output, "\n", 1); 139 140 /* Restore old terminal settings and signals. */ 141 if (memcmp(&term, &oterm, sizeof(term)) != 0) { 142 const int sigttou = signo[SIGTTOU]; 143 144 /* Ignore SIGTTOU generated when we are not the fg pgrp. */ 145 while (tcsetattr(input, TCSAFLUSH|TCSASOFT, &oterm) == -1 && 146 errno == EINTR && !signo[SIGTTOU]) 147 continue; 148 signo[SIGTTOU] = sigttou; 149 } 150 (void)sigaction(SIGALRM, &savealrm, NULL); 151 (void)sigaction(SIGHUP, &savehup, NULL); 152 (void)sigaction(SIGINT, &saveint, NULL); 153 (void)sigaction(SIGQUIT, &savequit, NULL); 154 (void)sigaction(SIGPIPE, &savepipe, NULL); 155 (void)sigaction(SIGTERM, &saveterm, NULL); 156 (void)sigaction(SIGTSTP, &savetstp, NULL); 157 (void)sigaction(SIGTTIN, &savettin, NULL); 158 (void)sigaction(SIGTTOU, &savettou, NULL); 159 if (input != STDIN_FILENO) 160 (void)close(input); 161 162 /* 163 * If we were interrupted by a signal, resend it to ourselves 164 * now that we have restored the signal handlers. 165 */ 166 for (i = 0; i < _NSIG; i++) { 167 if (signo[i]) { 168 kill(getpid(), i); 169 switch (i) { 170 case SIGTSTP: 171 case SIGTTIN: 172 case SIGTTOU: 173 need_restart = 1; 174 } 175 } 176 } 177 if (need_restart) 178 goto restart; 179 180 if (save_errno) 181 errno = save_errno; 182 return(nr == -1 ? NULL : buf); 183 } 184 DEF_WEAK(readpassphrase); 185 186 static void 187 handler(int s) 188 { 189 signo[s] = 1; 190 }