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 1.33 2005/05/02 21:13:22 markus Exp $"); 27 28 #include "xmalloc.h" 29 #include "misc.h" 30 #include "pathnames.h" 31 #include "log.h" 32 #include "ssh.h" 33 34 static char * 35 ssh_askpass(char *askpass, const char *msg) 36 { 37 pid_t pid; 38 size_t len; 39 char *pass; 40 int p[2], status, ret; 41 char buf[1024]; 42 43 if (fflush(stdout) != 0) 44 error("ssh_askpass: fflush: %s", strerror(errno)); 45 if (askpass == NULL) 46 fatal("internal error: askpass undefined"); 47 if (pipe(p) < 0) { 48 error("ssh_askpass: pipe: %s", strerror(errno)); 49 return NULL; 50 } 51 if ((pid = fork()) < 0) { 52 error("ssh_askpass: fork: %s", strerror(errno)); 53 return NULL; 54 } 55 if (pid == 0) { 56 seteuid(getuid()); 57 setuid(getuid()); 58 close(p[0]); 59 if (dup2(p[1], STDOUT_FILENO) < 0) 60 fatal("ssh_askpass: dup2: %s", strerror(errno)); 61 execlp(askpass, askpass, msg, (char *) 0); 62 fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno)); 63 } 64 close(p[1]); 65 66 len = ret = 0; 67 do { 68 ret = read(p[0], buf + len, sizeof(buf) - 1 - len); 69 if (ret == -1 && errno == EINTR) 70 continue; 71 if (ret <= 0) 72 break; 73 len += ret; 74 } while (sizeof(buf) - 1 - len > 0); 75 buf[len] = '\0'; 76 77 close(p[0]); 78 while (waitpid(pid, &status, 0) < 0) 79 if (errno != EINTR) 80 break; 81 82 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) { 83 memset(buf, 0, sizeof(buf)); 84 return NULL; 85 } 86 87 buf[strcspn(buf, "\r\n")] = '\0'; 88 pass = xstrdup(buf); 89 memset(buf, 0, sizeof(buf)); 90 return pass; 91 } 92 93 /* 94 * Reads a passphrase from /dev/tty with echo turned off/on. Returns the 95 * passphrase (allocated with xmalloc). Exits if EOF is encountered. If 96 * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no 97 * tty is available 98 */ 99 char * 100 read_passphrase(const char *prompt, int flags) 101 { 102 char *askpass = NULL, *ret, buf[1024]; 103 int rppflags, use_askpass = 0, ttyfd; 104 105 rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF; 106 if (flags & RP_USE_ASKPASS) 107 use_askpass = 1; 108 else if (flags & RP_ALLOW_STDIN) { 109 if (!isatty(STDIN_FILENO)) { 110 debug("read_passphrase: stdin is not a tty"); 111 use_askpass = 1; 112 } 113 } else { 114 rppflags |= RPP_REQUIRE_TTY; 115 ttyfd = open(_PATH_TTY, O_RDWR); 116 if (ttyfd >= 0) 117 close(ttyfd); 118 else { 119 debug("read_passphrase: can't open %s: %s", _PATH_TTY, 120 strerror(errno)); 121 use_askpass = 1; 122 } 123 } 124 125 if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL) 126 return (flags & RP_ALLOW_EOF) ? NULL : xstrdup(""); 127 128 if (use_askpass && getenv("DISPLAY")) { 129 if (getenv(SSH_ASKPASS_ENV)) 130 askpass = getenv(SSH_ASKPASS_ENV); 131 else 132 askpass = _PATH_SSH_ASKPASS_DEFAULT; 133 if ((ret = ssh_askpass(askpass, prompt)) == NULL) 134 if (!(flags & RP_ALLOW_EOF)) 135 return xstrdup(""); 136 return ret; 137 } 138 139 if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) { 140 if (flags & RP_ALLOW_EOF) 141 return NULL; 142 return xstrdup(""); 143 } 144 145 ret = xstrdup(buf); 146 memset(buf, 'x', sizeof buf); 147 return ret; 148 } 149 150 int 151 ask_permission(const char *fmt, ...) 152 { 153 va_list args; 154 char *p, prompt[1024]; 155 int allowed = 0; 156 157 va_start(args, fmt); 158 vsnprintf(prompt, sizeof(prompt), fmt, args); 159 va_end(args); 160 161 p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF); 162 if (p != NULL) { 163 /* 164 * Accept empty responses and responses consisting 165 * of the word "yes" as affirmative. 166 */ 167 if (*p == '\0' || *p == '\n' || 168 strcasecmp(p, "yes") == 0) 169 allowed = 1; 170 xfree(p); 171 } 172 173 return (allowed); 174 } 175