usr/src/cmd/ssh/libssh/common/readpass.c

   1 /*
   2  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 /*
   7  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #include "includes.h"
  31 RCSID("$OpenBSD: readpass.c,v 1.27 2002/03/26 15:58:46 markus Exp $");
  32
  33 #include "xmalloc.h"
  34 #include "readpass.h"
  35 #include "pathnames.h"
  36 #include "log.h"
  37 #include "ssh.h"
  38 #include <langinfo.h>
  39
  40 static char *
  41 ssh_askpass(char *askpass, const char *msg)
  42 {
  43         pid_t pid;
  44         size_t len;
  45         char *pass;
  46         int p[2], status, ret;
  47         char buf[1024];
  48
  49         if (fflush(stdout) != 0)
  50                 error("ssh_askpass: fflush: %s", strerror(errno));
  51         if (askpass == NULL)
  52                 fatal("internal error: askpass undefined");
  53         if (pipe(p) < 0) {
  54                 error("ssh_askpass: pipe: %s", strerror(errno));
  55                 return xstrdup("");
  56         }
  57         if ((pid = fork()) < 0) {
  58                 error("ssh_askpass: fork: %s", strerror(errno));
  59                 return xstrdup("");
  60         }
  61         if (pid == 0) {
  62                 seteuid(getuid());
  63                 setuid(getuid());
  64                 close(p[0]);
  65                 if (dup2(p[1], STDOUT_FILENO) < 0)
  66                         fatal("ssh_askpass: dup2: %s", strerror(errno));
  67                 execlp(askpass, askpass, msg, (char *) 0);
  68                 fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
  69         }
  70         close(p[1]);
  71
  72         len = ret = 0;
  73         do {
  74                 ret = read(p[0], buf + len, sizeof(buf) - 1 - len);
  75                 if (ret == -1 && errno == EINTR)
  76                         continue;
  77                 if (ret <= 0)
  78                         break;
  79                 len += ret;
  80         } while (sizeof(buf) - 1 - len > 0);
  81         buf[len] = '\0';
  82
  83         close(p[0]);
  84         while (waitpid(pid, &status, 0) < 0)
  85                 if (errno != EINTR)
  86                         break;
  87
  88         buf[strcspn(buf, "\r\n")] = '\0';
  89         pass = xstrdup(buf);
  90         memset(buf, 0, sizeof(buf));
  91         return pass;
  92 }
  93
  94 /*
  95  * Reads a passphrase from /dev/tty with echo turned off/on.  Returns the
  96  * passphrase (allocated with xmalloc).  Exits if EOF is encountered. If
  97  * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
  98  * tty is available
  99  */
 100 char *
 101 read_passphrase(const char *prompt, int flags)
 102 {
 103         char *askpass = NULL, *ret, buf[1024];
 104         int rppflags, use_askpass = 0, ttyfd;
 105
 106         rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
 107         if (flags & RP_ALLOW_STDIN) {
 108                 if (!isatty(STDIN_FILENO))
 109                         use_askpass = 1;
 110         } else {
 111                 rppflags |= RPP_REQUIRE_TTY;
 112                 ttyfd = open(_PATH_TTY, O_RDWR);
 113                 if (ttyfd >= 0)
 114                         close(ttyfd);
 115                 else
 116                         use_askpass = 1;
 117         }
 118
 119         if (use_askpass && getenv("DISPLAY")) {
 120                 if (getenv(SSH_ASKPASS_ENV))
 121                         askpass = getenv(SSH_ASKPASS_ENV);
 122                 else
 123                         askpass = _PATH_SSH_ASKPASS_DEFAULT;
 124                 return ssh_askpass(askpass, prompt);
 125         }
 126
 127         if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
 128                 if (flags & RP_ALLOW_EOF)
 129                         return NULL;
 130                 return xstrdup("");
 131         }
 132
 133         ret = xstrdup(buf);
 134         memset(buf, 'x', sizeof buf);
 135         return ret;
 136 }
 137
 138 int
 139 ask_permission(const char *fmt, ...)
 140 {
 141         va_list args;
 142         char *p, prompt[1024];
 143         int allowed = 0;
 144         char *yeschar = nl_langinfo(YESSTR);
 145
 146         va_start(args, fmt);
 147         vsnprintf(prompt, sizeof(prompt), fmt, args);
 148         va_end(args);
 149
 150         p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
 151         if (p != NULL) {
 152                 /*
 153                  * Accept empty responses and responses consisting
 154                  * of the word "yes" as affirmative.
 155                  */
 156                 if (*p == '\0' || *p == '\n' ||
 157                     strncasecmp(p, yeschar, 1) == 0)
 158                         allowed = 1;
 159                 xfree(p);
 160         }
 161
 162         return (allowed);
 163 }