source: trunk/third/openssh/readpass.c @ 16801

/*
 * Copyright (c) 1988, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "includes.h"
RCSID("$OpenBSD: readpass.c,v 1.22 2001/07/14 15:10:16 stevesk Exp $");

#include "xmalloc.h"
#include "readpass.h"
#include "pathnames.h"
#include "log.h"
#include "ssh.h"

static char *
ssh_askpass(char *askpass, const char *msg)
{
        pid_t pid;
        size_t len;
        char *nl, *pass;
        int p[2], status;
        char buf[1024];

        if (fflush(stdout) != 0)
                error("ssh_askpass: fflush: %s", strerror(errno));
        if (askpass == NULL)
                fatal("internal error: askpass undefined");
        if (pipe(p) < 0) {
                error("ssh_askpass: pipe: %s", strerror(errno));
                return xstrdup("");
        }
        if ((pid = fork()) < 0) {
                error("ssh_askpass: fork: %s", strerror(errno));
                return xstrdup("");
        }
        if (pid == 0) {
                seteuid(getuid());
                setuid(getuid());
                close(p[0]);
                if (dup2(p[1], STDOUT_FILENO) < 0)
                        fatal("ssh_askpass: dup2: %s", strerror(errno));
                execlp(askpass, askpass, msg, (char *) 0);
                fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
        }
        close(p[1]);
        len = read(p[0], buf, sizeof buf);
        close(p[0]);
        while (waitpid(pid, &status, 0) < 0)
                if (errno != EINTR)
                        break;
        if (len <= 1)
                return xstrdup("");
        nl = strchr(buf, '\n');
        if (nl)
                *nl = '\0';
        pass = xstrdup(buf);
        memset(buf, 0, sizeof(buf));
        return pass;
}

/*
 * Reads a passphrase from /dev/tty with echo turned off/on.  Returns the
 * passphrase (allocated with xmalloc).  Exits if EOF is encountered. If
 * RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
 * tty is available
 */
char *
read_passphrase(const char *prompt, int flags)
{
        char *askpass = NULL, *ret, buf[1024];
        int rppflags, use_askpass = 0, ttyfd;

        rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
        if (flags & RP_ALLOW_STDIN) {
                if (!isatty(STDIN_FILENO))
                        use_askpass = 1;
        } else {
                rppflags |= RPP_REQUIRE_TTY;
                ttyfd = open("/dev/tty", O_RDWR);
                if (ttyfd >= 0)
                        close(ttyfd);
                else
                        use_askpass = 1;
        }

        if (use_askpass && getenv("DISPLAY")) {
                if (getenv(SSH_ASKPASS_ENV))
                        askpass = getenv(SSH_ASKPASS_ENV);
                else
                        askpass = _PATH_SSH_ASKPASS_DEFAULT;
                return ssh_askpass(askpass, prompt);
        }

        if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL)
                return xstrdup("");

        ret = xstrdup(buf);
        memset(buf, 'x', sizeof buf);
        return ret;
}