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194 lines
5.0 KiB
C
194 lines
5.0 KiB
C
/* $OpenBSD: readpass.c,v 1.50 2014/02/02 03:44:31 djm Exp $ */
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#ifdef HAVE_PATHS_H
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# include <paths.h>
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#endif
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#include <signal.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "xmalloc.h"
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#include "misc.h"
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#include "pathnames.h"
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#include "log.h"
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#include "ssh.h"
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#include "uidswap.h"
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static char *
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ssh_askpass(char *askpass, const char *msg)
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{
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pid_t pid, ret;
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size_t len;
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char *pass;
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int p[2], status;
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char buf[1024];
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void (*osigchld)(int);
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if (fflush(stdout) != 0)
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error("ssh_askpass: fflush: %s", strerror(errno));
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if (askpass == NULL)
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fatal("internal error: askpass undefined");
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if (pipe(p) < 0) {
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error("ssh_askpass: pipe: %s", strerror(errno));
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return NULL;
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}
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osigchld = signal(SIGCHLD, SIG_DFL);
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if ((pid = fork()) < 0) {
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error("ssh_askpass: fork: %s", strerror(errno));
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signal(SIGCHLD, osigchld);
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return NULL;
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}
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if (pid == 0) {
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permanently_drop_suid(getuid());
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close(p[0]);
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if (dup2(p[1], STDOUT_FILENO) < 0)
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fatal("ssh_askpass: dup2: %s", strerror(errno));
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execlp(askpass, askpass, msg, (char *) 0);
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fatal("ssh_askpass: exec(%s): %s", askpass, strerror(errno));
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}
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close(p[1]);
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len = 0;
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do {
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ssize_t r = read(p[0], buf + len, sizeof(buf) - 1 - len);
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if (r == -1 && errno == EINTR)
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continue;
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if (r <= 0)
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break;
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len += r;
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} while (sizeof(buf) - 1 - len > 0);
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buf[len] = '\0';
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close(p[0]);
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while ((ret = waitpid(pid, &status, 0)) < 0)
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if (errno != EINTR)
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break;
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signal(SIGCHLD, osigchld);
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if (ret == -1 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
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explicit_bzero(buf, sizeof(buf));
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return NULL;
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}
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buf[strcspn(buf, "\r\n")] = '\0';
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pass = xstrdup(buf);
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explicit_bzero(buf, sizeof(buf));
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return pass;
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}
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/*
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* Reads a passphrase from /dev/tty with echo turned off/on. Returns the
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* passphrase (allocated with xmalloc). Exits if EOF is encountered. If
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* RP_ALLOW_STDIN is set, the passphrase will be read from stdin if no
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* tty is available
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*/
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char *
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read_passphrase(const char *prompt, int flags)
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{
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char *askpass = NULL, *ret, buf[1024];
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int rppflags, use_askpass = 0, ttyfd;
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rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
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if (flags & RP_USE_ASKPASS)
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use_askpass = 1;
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else if (flags & RP_ALLOW_STDIN) {
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if (!isatty(STDIN_FILENO)) {
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debug("read_passphrase: stdin is not a tty");
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use_askpass = 1;
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}
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} else {
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rppflags |= RPP_REQUIRE_TTY;
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ttyfd = open(_PATH_TTY, O_RDWR);
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if (ttyfd >= 0)
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close(ttyfd);
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else {
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debug("read_passphrase: can't open %s: %s", _PATH_TTY,
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strerror(errno));
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use_askpass = 1;
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}
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}
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if ((flags & RP_USE_ASKPASS) && getenv("DISPLAY") == NULL)
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return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
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if (use_askpass && getenv("DISPLAY")) {
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if (getenv(SSH_ASKPASS_ENV))
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askpass = getenv(SSH_ASKPASS_ENV);
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else
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askpass = _PATH_SSH_ASKPASS_DEFAULT;
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if ((ret = ssh_askpass(askpass, prompt)) == NULL)
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if (!(flags & RP_ALLOW_EOF))
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return xstrdup("");
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return ret;
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}
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if (readpassphrase(prompt, buf, sizeof buf, rppflags) == NULL) {
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if (flags & RP_ALLOW_EOF)
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return NULL;
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return xstrdup("");
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}
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ret = xstrdup(buf);
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explicit_bzero(buf, sizeof(buf));
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return ret;
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}
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int
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ask_permission(const char *fmt, ...)
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{
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va_list args;
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char *p, prompt[1024];
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int allowed = 0;
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va_start(args, fmt);
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vsnprintf(prompt, sizeof(prompt), fmt, args);
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va_end(args);
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p = read_passphrase(prompt, RP_USE_ASKPASS|RP_ALLOW_EOF);
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if (p != NULL) {
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/*
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* Accept empty responses and responses consisting
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* of the word "yes" as affirmative.
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*/
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if (*p == '\0' || *p == '\n' ||
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strcasecmp(p, "yes") == 0)
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allowed = 1;
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free(p);
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}
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return (allowed);
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}
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