/usr/share/perl5/Net/SFTP/Foreign/Backend/Unix.pm is in libnet-sftp-foreign-perl 1.87+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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our $VERSION = '1.76_03';
use strict;
use warnings;
use Carp;
our @CARP_NOT = qw(Net::SFTP::Foreign);
use Fcntl qw(O_NONBLOCK F_SETFL F_GETFL);
use POSIX ();
use Net::SFTP::Foreign::Helpers qw(_tcroak _ensure_list _debug _hexdump $debug);
use Net::SFTP::Foreign::Constants qw(SSH2_FX_BAD_MESSAGE
SFTP_ERR_REMOTE_BAD_MESSAGE);
use Time::HiRes qw(sleep time);
sub _new { shift }
sub _defaults {
( queue_size => 32 )
}
sub _init_transport_streams {
my (undef, $sftp) = @_;
for my $dir (qw(ssh_in ssh_out)) {
binmode $sftp->{$dir};
my $flags = fcntl($sftp->{$dir}, F_GETFL, 0);
fcntl($sftp->{$dir}, F_SETFL, $flags | O_NONBLOCK);
}
}
sub _open_dev_null {
my $sftp = shift;
my $dev_null;
unless (open $dev_null, '>', "/dev/null") {
$sftp->_conn_failed("Unable to redirect stderr to /dev/null");
return;
}
$dev_null
}
sub _fileno_dup_over {
my ($good_fn, $fh) = @_;
if (defined $fh) {
my @keep_open;
my $fn = fileno $fh;
for (1..5) {
$fn >= $good_fn and return $fn;
$fn = POSIX::dup($fn);
push @keep_open, $fn;
}
POSIX::_exit(255);
}
undef;
}
sub _open4 {
my $backend = shift;
my $sftp = shift;
my ($dad_in, $dad_out, $child_in, $child_out);
unless (pipe ($dad_in, $child_out) and
pipe ($child_in, $dad_out)) {
$sftp->_conn_failed("Unable to created pipes: $!");
return;
}
my $pid = fork;
unless ($pid) {
unless (defined $pid) {
$sftp->_conn_failed("Unable to fork new process: $!");
return;
}
close ($dad_in);
close ($dad_out);
shift; shift;
my $child_err = shift;
my $pty = shift;
$pty->make_slave_controlling_terminal if defined $pty;
my $child_err_fno = eval { no warnings; fileno($child_err ? $child_err : *STDERR) };
my $child_err_safe; # passed handler may be tied, so we
# duplicate it in order to get a plain OS
# handler.
if (defined $child_err_fno and $child_err_fno >= 0) {
open $child_err_safe, ">&=$child_err_fno" or POSIX::_exit(1);
}
else {
open $child_err_safe, ">/dev/null" or POSIX::_exit(1);
}
my $child_in_fno = _fileno_dup_over(0 => $child_in );
my $child_out_fno = _fileno_dup_over(1 => $child_out );
my $child_err_safe_fno = _fileno_dup_over(2 => $child_err_safe);
unless (($child_in_fno == 0 or POSIX::dup2($child_in_fno, 0)) and
($child_out_fno == 1 or POSIX::dup2($child_out_fno, 1)) and
($child_err_safe_fno == 2 or POSIX::dup2($child_err_safe_fno, 2))) {
POSIX::_exit(1);
}
do { exec @_ };
POSIX::_exit(1);
}
close $child_in;
close $child_out;
$_[0] = $dad_in;
$_[1] = $dad_out;
$pid;
}
sub _init_transport {
my ($backend, $sftp, $opts) = @_;
my $transport = delete $opts->{transport};
if (defined $transport) {
if (ref $transport eq 'ARRAY') {
@{$sftp}{qw(ssh_in ssh_out pid)} = @$transport;
}
else {
$sftp->{ssh_in} = $sftp->{ssh_out} = $transport;
$sftp->{_ssh_out_is_not_dupped} = 1;
}
}
else {
my $user = delete $opts->{user};
my $pass = delete $opts->{passphrase};
my $ask_for_username_at_login;
my $pass_is_passphrase;
my $password_prompt;
if (defined $pass) {
$pass_is_passphrase = 1;
}
else {
$pass = delete $opts->{password};
if (defined $pass) {
$sftp->{_password_authentication} = 1;
$password_prompt = $sftp->{_password_prompt} = delete $opts->{password_prompt};
if (defined $password_prompt) {
unless (ref $password_prompt eq 'Regexp') {
$password_prompt = quotemeta $password_prompt;
$password_prompt = qr/$password_prompt\s*$/i;
}
}
$ask_for_username_at_login =
$sftp->{_ask_for_username_at_login} =
( delete($opts->{ask_for_username_at_login}) ||
delete($opts->{asks_for_username_at_login}) );
if ($ask_for_username_at_login) {
croak "ask_for_username_at_login set but user was not given" unless defined $user;
croak "ask_for_username_at_login can not be used with a custom password prompt"
if defined $password_prompt;
}
}
}
delete $opts->{expect_log_user}; # backward compatibility, not used anymore
my $stderr_discard = delete $opts->{stderr_discard};
my $stderr_fh = ($stderr_discard ? undef : delete $opts->{stderr_fh});
my $open2_cmd = delete $opts->{open2_cmd};
my $ssh_cmd_interface = delete $opts->{ssh_cmd_interface};
my @open2_cmd;
if (defined $open2_cmd) {
@open2_cmd = _ensure_list($open2_cmd);
}
else {
my $host = delete $opts->{host};
defined $host or croak "sftp target host not defined";
my $key_path = delete $opts->{key_path};
my $ssh_cmd = delete $opts->{ssh_cmd};
$ssh_cmd = 'ssh' unless defined $ssh_cmd;
@open2_cmd = _ensure_list $ssh_cmd;
unless (defined $ssh_cmd_interface) {
$ssh_cmd_interface = ( "@open2_cmd" =~ /\bplink\b/i ? 'plink' :
"@open2_cmd" =~ /\bsshg3\b/i ? 'tectia' :
'ssh' );
}
my $port = delete $opts->{port};
my $ssh1 = delete $opts->{ssh1};
my $more = delete $opts->{more};
defined $more and !ref($more) and $more =~ /^-\w\s+\S/ and
warnings::warnif("Net::SFTP::Foreign", "'more' argument looks like it should be split first");
my @more = _ensure_list $more;
my @preferred_authentications;
if (defined $key_path) {
push @preferred_authentications, 'publickey';
push @open2_cmd, map { -i => $_ } _ensure_list $key_path;
}
if ($ssh_cmd_interface eq 'plink') {
push @open2_cmd, -P => $port if defined $port;
if (defined $pass and !$pass_is_passphrase) {
warnings::warnif("Net::SFTP::Foreign", "using insecure password authentication with plink");
push @open2_cmd, -pw => $pass;
undef $pass;
}
}
elsif ($ssh_cmd_interface eq 'ssh') {
push @open2_cmd, -p => $port if defined $port;
if (defined $pass and !$pass_is_passphrase) {
push @open2_cmd, -o => 'NumberOfPasswordPrompts=1';
push @preferred_authentications, ('keyboard-interactive', 'password');
}
if (@preferred_authentications
and not grep { $more[$_] eq '-o' and
$more[$_ + 1] =~ /^PreferredAuthentications\W/ } 0..$#more-1) {
push @open2_cmd, -o => 'PreferredAuthentications=' . join(',', @preferred_authentications);
}
}
elsif ($ssh_cmd_interface eq 'tectia') {
}
else {
die "Unsupported ssh_cmd_interface '$ssh_cmd_interface'";
}
push @open2_cmd, -l => $user if defined $user;
push @open2_cmd, @more;
push @open2_cmd, $host;
push @open2_cmd, ($ssh1 ? "/usr/lib/sftp-server" : -s => 'sftp');
}
my $redirect_stderr_to_tty = ( defined $pass and
( delete $opts->{redirect_stderr_to_tty} or $ssh_cmd_interface eq 'tectia' ) );
$redirect_stderr_to_tty and ($stderr_discard or $stderr_fh)
and croak "stderr_discard or stderr_fh can not be used together with password/passphrase "
. "authentication when Tectia client is used";
$debug and $debug & 1 and _debug "ssh cmd: @open2_cmd\n";
%$opts and return; # Net::SFTP::Foreign will find the
# unhandled options and croak
if (${^TAINT} and Scalar::Util::tainted($ENV{PATH})) {
_tcroak('Insecure $ENV{PATH}')
}
if ($stderr_discard) {
$stderr_fh = $backend->_open_dev_null($sftp) or return;
}
if (defined $pass) {
# user has requested to use a password or a passphrase for
# authentication we use IO::Pty to handle that
eval { require IO::Pty; 1 }
or croak "password authentication not available, IO::Pty is not installed or failed to load: $@";
local ($ENV{SSH_ASKPASS}, $ENV{SSH_AUTH_SOCK}) if $pass_is_passphrase;
my $name = $pass_is_passphrase ? 'Passphrase' : 'Password';
my $child;
my $pty = IO::Pty->new;
$redirect_stderr_to_tty and $stderr_fh = $pty->slave;
$child = $backend->_open4($sftp, $sftp->{ssh_in}, $sftp->{ssh_out}, $stderr_fh, $pty, @open2_cmd);
unless (defined $child) {
$sftp->_conn_failed("Bad ssh command", $!);
return;
}
$sftp->{pid} = $child;
open my $pty_dup, '+>&', $pty; # store pty as a file handler instead of a object in
# order to save it from being destroyed too early
# during global destruction
$sftp->{_pty} = $pty_dup;
$debug and $debug & 65536 and _debug "starting password authentication";
my $rv = '';
vec($rv, fileno($pty), 1) = 1;
my $buffer = '';
my $at = 0;
my $password_sent;
my $start_time = time;
while(1) {
if (defined $sftp->{_timeout}) {
$debug and $debug & 65536 and _debug "checking timeout, max: $sftp->{_timeout}, ellapsed: " . (time - $start_time);
if (time - $start_time > $sftp->{_timeout}) {
$sftp->_conn_failed("login procedure timed out");
return;
}
}
if (waitpid($child, POSIX::WNOHANG()) > 0) {
undef $sftp->{pid};
my $err = $? >> 8;
$sftp->_conn_failed("SSH slave exited unexpectedly with error code $err");
return;
}
$debug and $debug & 65536 and _debug "waiting for data from the pty to become available";
my $rv1 = $rv;
select($rv1, undef, undef, 1) > 0 or next;
if (my $bytes = sysread($pty, $buffer, 4096, length $buffer)) {
if ($debug and $debug & 65536) {
_debug "$bytes bytes readed from pty:";
_hexdump substr($buffer, -$bytes);
}
if ($buffer =~ /^The authenticity of host/mi or
$buffer =~ /^Warning: the \S+ host key for/mi) {
$sftp->_conn_failed("the authenticity of the target host can't be established, " .
"the remote host public key is probably not present on the " .
"'~/.ssh/known_hosts' file");
return;
}
if ($password_sent) {
$debug and $debug & 65536 and _debug "looking for password ok";
last if substr($buffer, $at) =~ /\n$/;
}
else {
$debug and $debug & 65536 and _debug "looking for user/password prompt";
my $re = ( defined $password_prompt
? $password_prompt
: qr/(user|name|login)?[:?]\s*$/i );
$debug and $debug & 65536 and _debug "matching against $re";
if (substr($buffer, $at) =~ $re) {
if ($ask_for_username_at_login and
($ask_for_username_at_login ne 'auto' or defined $1)) {
$debug and $debug & 65536 and _debug "sending username";
print $pty "$user\n";
undef $ask_for_username_at_login;
}
else {
$debug and $debug & 65536 and _debug "sending password";
print $pty "$pass\n";
$password_sent = 1;
}
$at = length $buffer;
}
}
}
else {
$debug and $debug & 65536 and _debug "no data available from pty, delaying until next read";
sleep 0.1;
}
}
$debug and $debug & 65536 and _debug "password authentication done";
$pty->close_slave();
}
else {
$sftp->{pid} = $backend->_open4($sftp, $sftp->{ssh_in}, $sftp->{ssh_out}, $stderr_fh, undef, @open2_cmd);
unless (defined $sftp->{pid}) {
$sftp->_conn_failed("Bad ssh command", $!);
return;
}
}
}
$backend->_init_transport_streams($sftp);
}
sub _after_init {
my ($backend, $sftp) = @_;
if ($sftp->{pid} and not $sftp->error) {
# do not propagate signals sent from the terminal to the
# slave SSH:
local ($@, $!);
eval { setpgrp($sftp->{pid}, 0) };
}
}
sub _do_io {
my (undef, $sftp, $timeout) = @_;
$debug and $debug & 32 and _debug(sprintf "_do_io connected: %s", $sftp->{_connected} || 0);
return undef unless $sftp->{_connected};
my $fnoout = fileno $sftp->{ssh_out};
my $fnoin = fileno $sftp->{ssh_in};
my ($rv, $wv) = ('', '');
vec($rv, $fnoin, 1) = 1;
vec($wv, $fnoout, 1) = 1;
my $bin = \$sftp->{_bin};
my $bout = \$sftp->{_bout};
local $SIG{PIPE} = 'IGNORE';
my $len;
while (1) {
my $lbin = length $$bin;
if (defined $len) {
return 1 if $lbin >= $len;
}
elsif ($lbin >= 4) {
$len = 4 + unpack N => $$bin;
if ($len > 256 * 1024) {
$sftp->_set_status(SSH2_FX_BAD_MESSAGE);
$sftp->_set_error(SFTP_ERR_REMOTE_BAD_MESSAGE,
"bad remote message received");
return undef;
}
return 1 if $lbin >= $len;
}
my $rv1 = $rv;
my $wv1 = length($$bout) ? $wv : '';
$debug and $debug & 32 and _debug("_do_io select(-,-,-, ". (defined $timeout ? $timeout : 'undef') .")");
my $n = select($rv1, $wv1, undef, $timeout);
if ($n > 0) {
if (vec($wv1, $fnoout, 1)) {
my $written = syswrite($sftp->{ssh_out}, $$bout, 64 * 1024);
if ($debug and $debug & 32) {
_debug (sprintf "_do_io write queue: %d, syswrite: %s, max: %d, \$!: %s",
length $$bout,
(defined $written ? $written : 'undef'),
64 * 1024, $!);
$debug & 2048 and $written and _hexdump(substr($$bout, 0, $written));
}
if ($written) {
substr($$bout, 0, $written, '');
}
elsif ($! != Errno::EAGAIN() and $! != Errno::EINTR()) {
$sftp->_conn_lost;
return undef;
}
}
if (vec($rv1, $fnoin, 1)) {
my $read = sysread($sftp->{ssh_in}, $$bin, 64 * 1024, length($$bin));
if ($debug and $debug & 32) {
_debug (sprintf "_do_io read sysread: %s, total read: %d, \$!: %s",
(defined $read ? $read : 'undef'),
length $$bin,
$!);
$debug & 1024 and $read and _hexdump(substr($$bin, -$read));
}
if (!$read and $! != Errno::EAGAIN() and $! != Errno::EINTR()) {
$sftp->_conn_lost;
return undef;
}
}
}
else {
$debug and $debug & 32 and _debug "_do_io select failed: $!";
next if ($n < 0 and ($! == Errno::EINTR() or $! == Errno::EAGAIN()));
return undef;
}
}
}
1;
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