Release notes are available at https://www.openssh.com/txt/release-9.1 9.1 contains fixes for three minor memory safety problems; these have lready been merged to the copy of OpenSSH 9.0 that is in the FreeBSD base system. Some highlights copied from the release notes: Potentially-incompatible changes -------------------------------- * ssh(1), sshd(8): SetEnv directives in ssh_config and sshd_config are now first-match-wins to match other directives. Previously if an environment variable was multiply specified the last set value would have been used. bz3438 * ssh-keygen(8): ssh-keygen -A (generate all default host key types) will no longer generate DSA keys, as these are insecure and have not been used by default for some years. New features ------------ * ssh(1), sshd(8): add a RequiredRSASize directive to set a minimum RSA key length. Keys below this length will be ignored for user authentication and for host authentication in sshd(8). * sftp-server(8): add a "users-groups-by-id@openssh.com" extension request that allows the client to obtain user/group names that correspond to a set of uids/gids. * sftp(1): use "users-groups-by-id@openssh.com" sftp-server extension (when available) to fill in user/group names for directory listings. * sftp-server(8): support the "home-directory" extension request defined in draft-ietf-secsh-filexfer-extensions-00. This overlaps a bit with the existing "expand-path@openssh.com", but some other clients support it. * ssh-keygen(1), sshd(8): allow certificate validity intervals, sshsig verification times and authorized_keys expiry-time options to accept dates in the UTC time zone in addition to the default of interpreting them in the system time zone. YYYYMMDD and YYMMDDHHMM[SS] dates/times will be interpreted as UTC if suffixed with a 'Z' character. Also allow certificate validity intervals to be specified in raw seconds-since-epoch as hex value, e.g. -V 0x1234:0x4567890. This is intended for use by regress tests and other tools that call ssh-keygen as part of a CA workflow. bz3468 * sftp(1): allow arguments to the sftp -D option, e.g. sftp -D "/usr/libexec/sftp-server -el debug3" * ssh-keygen(1): allow the existing -U (use agent) flag to work with "-Y sign" operations, where it will be interpreted to require that the private keys is hosted in an agent; bz3429 MFC after: 2 weeks Relnotes: Yes Sponsored by: The FreeBSD Foundation
333 lines
8.3 KiB
C
333 lines
8.3 KiB
C
/* $OpenBSD: readpass.c,v 1.70 2022/05/27 04:27:49 dtucker 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, const char *env_hint)
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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_f("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) == -1) {
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error_f("pipe: %s", strerror(errno));
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return NULL;
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}
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osigchld = ssh_signal(SIGCHLD, SIG_DFL);
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if ((pid = fork()) == -1) {
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error_f("fork: %s", strerror(errno));
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ssh_signal(SIGCHLD, osigchld);
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return NULL;
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}
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if (pid == 0) {
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close(p[0]);
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if (dup2(p[1], STDOUT_FILENO) == -1)
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fatal_f("dup2: %s", strerror(errno));
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if (env_hint != NULL)
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setenv("SSH_ASKPASS_PROMPT", env_hint, 1);
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execlp(askpass, askpass, msg, (char *)NULL);
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fatal_f("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)) == -1)
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if (errno != EINTR)
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break;
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ssh_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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/* private/internal read_passphrase flags */
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#define RP_ASK_PERMISSION 0x8000 /* pass hint to askpass for confirm UI */
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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 or askpass program 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 cr = '\r', *askpass = NULL, *ret, buf[1024];
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int rppflags, ttyfd, use_askpass = 0, allow_askpass = 0;
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const char *askpass_hint = NULL;
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const char *s;
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if ((s = getenv("DISPLAY")) != NULL)
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allow_askpass = *s != '\0';
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if ((s = getenv(SSH_ASKPASS_REQUIRE_ENV)) != NULL) {
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if (strcasecmp(s, "force") == 0) {
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use_askpass = 1;
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allow_askpass = 1;
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} else if (strcasecmp(s, "prefer") == 0)
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use_askpass = allow_askpass;
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else if (strcasecmp(s, "never") == 0)
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allow_askpass = 0;
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}
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rppflags = (flags & RP_ECHO) ? RPP_ECHO_ON : RPP_ECHO_OFF;
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if (use_askpass)
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debug_f("requested to askpass");
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else 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_f("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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/*
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* If we're on a tty, ensure that show the prompt at
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* the beginning of the line. This will hopefully
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* clobber any password characters the user has
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* optimistically typed before echo is disabled.
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*/
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(void)write(ttyfd, &cr, 1);
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close(ttyfd);
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} else {
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debug_f("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) && !allow_askpass)
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return (flags & RP_ALLOW_EOF) ? NULL : xstrdup("");
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if (use_askpass && allow_askpass) {
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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 ((flags & RP_ASK_PERMISSION) != 0)
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askpass_hint = "confirm";
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if ((ret = ssh_askpass(askpass, prompt, askpass_hint)) == 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,
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RP_USE_ASKPASS|RP_ALLOW_EOF|RP_ASK_PERMISSION);
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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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static void
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writemsg(const char *msg)
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{
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(void)write(STDERR_FILENO, "\r", 1);
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(void)write(STDERR_FILENO, msg, strlen(msg));
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(void)write(STDERR_FILENO, "\r\n", 2);
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}
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struct notifier_ctx {
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pid_t pid;
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void (*osigchld)(int);
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};
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struct notifier_ctx *
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notify_start(int force_askpass, const char *fmt, ...)
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{
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va_list args;
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char *prompt = NULL;
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pid_t pid = -1;
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void (*osigchld)(int) = NULL;
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const char *askpass, *s;
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struct notifier_ctx *ret = NULL;
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va_start(args, fmt);
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xvasprintf(&prompt, fmt, args);
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va_end(args);
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if (fflush(NULL) != 0)
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error_f("fflush: %s", strerror(errno));
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if (!force_askpass && isatty(STDERR_FILENO)) {
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writemsg(prompt);
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goto out_ctx;
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}
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if ((askpass = getenv("SSH_ASKPASS")) == NULL)
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askpass = _PATH_SSH_ASKPASS_DEFAULT;
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if (*askpass == '\0') {
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debug3_f("cannot notify: no askpass");
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goto out;
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}
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if (getenv("DISPLAY") == NULL &&
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((s = getenv(SSH_ASKPASS_REQUIRE_ENV)) == NULL ||
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strcmp(s, "force") != 0)) {
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debug3_f("cannot notify: no display");
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goto out;
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}
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osigchld = ssh_signal(SIGCHLD, SIG_DFL);
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if ((pid = fork()) == -1) {
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error_f("fork: %s", strerror(errno));
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ssh_signal(SIGCHLD, osigchld);
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free(prompt);
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return NULL;
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}
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if (pid == 0) {
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if (stdfd_devnull(1, 1, 0) == -1)
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fatal_f("stdfd_devnull failed");
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closefrom(STDERR_FILENO + 1);
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setenv("SSH_ASKPASS_PROMPT", "none", 1); /* hint to UI */
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execlp(askpass, askpass, prompt, (char *)NULL);
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error_f("exec(%s): %s", askpass, strerror(errno));
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_exit(1);
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/* NOTREACHED */
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}
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out_ctx:
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if ((ret = calloc(1, sizeof(*ret))) == NULL) {
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if (pid != -1)
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kill(pid, SIGTERM);
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fatal_f("calloc failed");
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}
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ret->pid = pid;
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ret->osigchld = osigchld;
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out:
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free(prompt);
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return ret;
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}
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void
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notify_complete(struct notifier_ctx *ctx, const char *fmt, ...)
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{
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int ret;
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char *msg = NULL;
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va_list args;
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if (ctx != NULL && fmt != NULL && ctx->pid == -1) {
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/*
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* notify_start wrote to stderr, so send conclusion message
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* there too
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*/
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va_start(args, fmt);
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xvasprintf(&msg, fmt, args);
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va_end(args);
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writemsg(msg);
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free(msg);
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}
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if (ctx == NULL || ctx->pid <= 0) {
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free(ctx);
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return;
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}
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kill(ctx->pid, SIGTERM);
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while ((ret = waitpid(ctx->pid, NULL, 0)) == -1) {
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if (errno != EINTR)
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break;
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}
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if (ret == -1)
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fatal_f("waitpid: %s", strerror(errno));
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ssh_signal(SIGCHLD, ctx->osigchld);
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free(ctx);
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}
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