1 /* 2 * Copyright (c) 2001 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25 #include "includes.h" 26 RCSID("$OpenBSD: readpass.c,v 1.27 2002/03/26 15:58:46 markus Exp $"); 27 28 #pragma ident "%Z%%M% %I% %E% SMI" 29 30 #include "xmalloc.h" 31 #include "readpass.h" 32 #include "pathnames.h" 33 #include "log.h" 34 #include "ssh.h" 35 36 static char * 37 ssh_askpass(char *askpass, const char *msg) 38 { 39 pid_t pid; 40 size_t len; 41 char *pass; 42 int p[2], status, ret; 43 char buf[1024]; 44 45 if (fflush(stdout) != 0) 46 error("ssh_askpass: fflush: %s", strerror(errno)); 47 if (askpass == NULL) 48 fatal("internal error: askpass undefined"); 49 if (pipe(p) < 0) { 50 error("ssh_askpass: pipe: %s", strerror(errno)); 51 return xstrdup(""); 52 } 53 if ((pid = fork()) < 0) { 54 error("ssh_askpass: fork: %s", strerror(errno)); 55 return xstrdup(""); 56 } 57 if (pid == 0) { 58 seteuid(getuid()); 59 setuid(getuid()); 60 close(p[0]); 61 if (dup2(p[1], STDOUT_FILENO) < 0) 62 fatal("ssh_askpass: dup2: %s", strerror(errno)); 63 execlp(askpass, askpass, msg, (char *) 0); 64 fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno)); 65 } 66 close(p[1]); 67 68 len = ret = 0; 69 do { 70 ret = read(p[0], buf + len, sizeof(buf) - 1 - len); 71 if (ret == -1 && errno == EINTR) 72 continue; 73 if (ret <= 0) 74 break; 75 len += ret; 76 } while (sizeof(buf) - 1 - len > 0); 77 buf[len] = '\0'; 78 79 close(p[0]); 80 while (waitpid(pid, &status, 0) < 0) 81 if (errno != EINTR) 82 break; 83 84 buf[strcspn(buf, "\r\n")] = '\0'; 85 pass = xstrdup(buf); 86 memset(buf, 0, sizeof(buf)); 87 return pass; 88 } 89 90 /* 91 * Reads a passphrase from /dev/tty with echo turned off/on. Returns the 92 * passphrase (allocated with xmalloc). Exits if EOF is encountered. If 93 * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no 94 * tty is available 95 */ 96 char * 97 read_passphrase(const char *prompt, int flags) 98 { 99 char *askpass = NULL, *ret, buf[1024]; 100 int rppflags, use_askpass = 0, ttyfd; 101 102 rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF; 103 if (flags & RP_ALLOW_STDIN) { 104 if (!isatty(STDIN_FILENO)) 105 use_askpass = 1; 106 } else { 107 rppflags |= RPP_REQUIRE_TTY; 108 ttyfd = open(_PATH_TTY, O_RDWR); 109 if (ttyfd >= 0) 110 close(ttyfd); 111 else 112 use_askpass = 1; 113 } 114 115 if (use_askpass && getenv("DISPLAY")) { 116 if (getenv(SSH_ASKPASS_ENV)) 117 askpass = getenv(SSH_ASKPASS_ENV); 118 else 119 askpass = _PATH_SSH_ASKPASS_DEFAULT; 120 return ssh_askpass(askpass, prompt); 121 } 122 123 if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) { 124 if (flags & RP_ALLOW_EOF) 125 return NULL; 126 return xstrdup(""); 127 } 128 129 ret = xstrdup(buf); 130 memset(buf, 'x', sizeof buf); 131 return ret; 132 } 133