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#!/usr/bin/perl -T
#----------------------------------------------------------------------
# ACME client written with process isolation and minimal privileges in mind
# Copyright © 2015-2017 Guilhem Moulin <guilhem@fripost.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#----------------------------------------------------------------------
use v5.14.2;
use strict;
use warnings;
# Usage: client COMMAND CONFIG_FD SOCKET_FD [ARGUMENTS]
#
# fdopen(3) the file descriptor SOCKET_FD (corresponding to the
# listening lacme-accountd socket), connect(2) to it to retrieve the
# account key's public parameters and later send data to be signed by
# the master component (using the account key).
#
# CONFIG_FD is a read-only file descriptor associated with the
# configuration file at pos 0. (This is needed since this process
# doesn't know its name and might not have read access to it.)
#
# NOTE: one needs to chdir(2) to an appropriate ACME challenge directory
# before running this program, since challenge tokens are (on purpose)
# only written to the current directory. If COMMAND is challenge-less,
# one should chdir(2) to the root directory "/" instead.
#
# NOTE: one should run this program as an unprivileged user:group such
# as "nobody:nogroup"; bind(2)'ing to a restricted UNIX socket (for
# instance own by another user and created with umask 0177) is not a
# problem since SOCKET_FD can be bound as root prior to the execve(2).
my $PROTOCOL_VERSION = 1;
use Errno 'EEXIST';
use Fcntl qw/O_CREAT O_EXCL O_WRONLY/;
use Digest::SHA qw/sha256 sha256_hex/;
use MIME::Base64 qw/encode_base64 encode_base64url/;
use LWP::UserAgent ();
use Types::Serialiser ();
use JSON ();
use Config::Tiny ();
# Clean up PATH
$ENV{PATH} = join ':', qw{/usr/bin /bin};
delete @ENV{qw/IFS CDPATH ENV BASH_ENV/};
my $COMMAND = shift @ARGV // die;
# Untaint and fdopen(3) the configuration file and listening socket
(shift @ARGV // die) =~ /\A(\d+)\z/ or die;
open (my $CONFFILE, '<&=', $1+0) or die "fdopen $1: $!";
(shift @ARGV // die) =~ /\A(\d+)\z/ or die;
open (my $S, '+<&=', $1+0) or die "fdopen $1: $!";
#############################################################################
# Read the protocol version and JSON Web Key (RFC 7517) from the
# lacme-accountd socket
#
die "Error: Invalid client version\n" unless
$S->getline() =~ /\A(\d+) OK(?:.*)\r\n\z/ and $1 == $PROTOCOL_VERSION;
my $JWK = JSON::->new->decode($S->getline());
my $KID;
# JSON keys need to be sorted lexicographically (for instance in the thumbprint)
sub json() { JSON::->new->utf8->canonical(); }
my $JWK_thumbprint = encode_base64url(sha256(json()->encode($JWK)));
my $NONCE;
#############################################################################
# Parse configuration (already validated by the master) and create the
# LWP::UserAgent object
#
my $CONFIG = do {
my $conf = do { local $/ = undef; <$CONFFILE> };
close $CONFFILE or die "Can't close: $!";
my $h = Config::Tiny::->read_string($conf) or die Config::Tiny::->errstr()."\n";
$h->{_} //= {};
$h->{client}->{$_} //= $h->{_}->{$_} foreach keys %{$h->{_}}; # add defaults
$h->{client};
};
my $UA = do {
my %args = %$CONFIG;
my $verify = lc (delete $args{SSL_verify} // 'Yes') eq 'no' ? 0 : 1;
my %ssl_opts = ( verify_hostname => $verify );
$ssl_opts{$_} = $args{$_} foreach grep /^SSL_/, keys %args;
LWP::UserAgent::->new( ssl_opts => \%ssl_opts );
} // die "Can't create LWP::UserAgent object";
$UA->default_header( 'Accept-Language' => 'en' );
#############################################################################
# Send an HTTP request to the ACME server. If $json is defined, send
# its encoding as the request content, with "application/jose+json" as
# Content-Type.
#
sub request($$;$) {
my ($method, $uri, $json) = @_;
print STDERR "[$$] >>> $method $uri <<<\n" if $ENV{DEBUG};
my $req = HTTP::Request::->new($method => $uri) or die "Can't $method $uri";
if (defined $json) {
$req->content_type('application/jose+json');
$req->content(json()->encode($json));
}
my $r = $UA->request($req) or die "Can't $method $uri";
$NONCE //= $r->header('Replay-Nonce'); # undef $NONCE if the header is missing
print STDERR "[$$] >>> ", $r->status_line, "\n", $r->headers->as_string("\n") if $ENV{DEBUG};
return $r;
}
# The request's Status Line; if the Content-Type is
# application/problem+json (RFC 7807), parse the decoded content as JSON
# and add the value of the 'detail' field to the Status Line.
sub request_status_line($) {
my $r = shift;
my $msg = $r->status_line;
if (!$r->is_success() and $r->content_type() eq 'application/problem+json') {
my $content = json()->decode($r->decoded_content());
print STDERR json()->pretty->encode($content), "\n" if $ENV{DEBUG};
$msg .= " (".$content->{detail}.")" if defined $content->{detail};
}
return $msg;
}
# The request's Retry-After header (RFC 7231 sec. 7.1.3), converted to
# waiting time in seconds.
sub request_retry_after($) {
my $r = shift;
my $v = $r->header('Retry-After');
if (defined $v and $v !~ /\A\d+\z/) {
require 'Date/Parse.pm';
$v = Date::Parse::str2time($v);
if (defined $v) {
$v = $v - time;
undef $v if $v <= 0;
}
}
return $v;
}
# Parse and return the request's decoded content as JSON; or print the
# Status Line and fail if the request failed.
# If $dump is set, also pretty-print the decoded content.
sub request_json_decode($;$$) {
my $r = shift;
my $dump = shift || $ENV{DEBUG};
my $fh = shift // \*STDERR;
die request_status_line($r), "\n" unless $r->is_success();
my $content = $r->decoded_content();
die "Content-Type: ".$r->content_type()." is not application/json\n"
unless $r->content_type() eq 'application/json';
my $json = json()->decode($content);
print $fh (-t $fh ? (json()->pretty->encode($json)."\n") : $content)
if $dump;
return $json;
}
#############################################################################
# JSON-encode the hash reference $h and send it to the ACME server $uri
# encapsulated it in a JSON Web Signature (JWS).
# https://tools.ietf.org/html/draft-ietf-acme-acme-12
#
sub acme($@) {
my $uri = shift;
die "Missing nonce\n" unless defined $NONCE;
# Produce the JSON Web Signature: RFC 7515 section 5
my %header = ( alg => 'RS256', nonce => $NONCE, url => $uri );
defined $KID ? ($header{kid} = $KID) : ($header{jwk} = $JWK);
my $payload = encode_base64url(json()->encode({ @_ }));
my $protected = encode_base64url(json()->encode(\%header));
my $data = $protected .'.'. $payload;
$S->printflush($data, "\r\n");
my $sig = $S->getline();
$sig =~ s/\r\n\z// or die;
undef $NONCE; # consume the nonce
# Flattened JSON Serialization, RFC 7515 section 7.2.2
request(POST => $uri, {
payload => $payload,
protected => $protected,
signature => $sig
});
}
my $SERVER_URI = $CONFIG->{server} // 'https://acme-v02.api.letsencrypt.org/directory';
my %RES;
# Get the resource URI from the directory
sub acme_resource($%) {
my $r = shift;
unless (%RES) {
# query the ACME directory to get resources URIs
%RES = %{ request_json_decode(request(GET => $SERVER_URI)) };
# send a HEAD request to the newNonce resource to get a fresh nonce
die "Unknown resource 'newNonce'\n" unless defined $RES{newNonce};
request(HEAD => $RES{newNonce});
}
my $uri = $RES{$r} // die "Unknown resource '$r'\n";
acme($uri, @_);
}
# Set the key ID (registration URI)
sub set_kid(;$) {
my $die = shift // 1;
my $r = acme_resource('newAccount', onlyReturnExisting => Types::Serialiser::true );
if ($r->is_success()) {
$KID = $r->header('Location');
} elsif ($die) {
die request_status_line($r), "\n";
}
}
#############################################################################
# account FLAGS [CONTACT ..]
#
if ($COMMAND eq 'account') {
my $flags = shift @ARGV;
my %h = ( contact => \@ARGV ) if @ARGV;
$h{onlyReturnExisting} = Types::Serialiser::true unless $flags & 0x01;
$h{termsOfServiceAgreed} = Types::Serialiser::true if $flags & 0x02;
print STDERR "Requesting new registration ".(@ARGV ? ("for ".join(', ', @ARGV)) : "")."\n"
if $flags & 0x01;
my $r = acme_resource('newAccount', %h);
# TODO: list account orders: https://github.com/letsencrypt/boulder/issues/3335
if ($r->is_success()) {
$KID = $r->header('Location');
$r = acme($KID, %h);
request_json_decode($r, 1, \*STDOUT)
if $r->is_success() and $r->content_type() eq 'application/json';
}
print STDERR request_status_line($r), "\n"
if !$r->is_success() or $ENV{DEBUG};
exit ($r->is_success() ? 0 : 1);
}
#############################################################################
# newOrder AUTHZ [AUTHZ ..]
# Read the CSR (in DER format) from STDIN, print the cert (in PEM format
# to STDOUT)
#
elsif ($COMMAND eq 'newOrder') {
die unless @ARGV;
my $timeout = $CONFIG->{timeout} // 10;
my $csr = do { local $/ = undef; <STDIN> };
set_kid();
my @identifiers = map {{ type => 'dns', value => $_ }} @ARGV;
my $r = acme_resource('newOrder', identifiers => \@identifiers);
my $order = request_json_decode($r);
my $orderurl = $r->header('Location');
foreach (@{$order->{authorizations}}) {
my $authz = request_json_decode(request(GET => $_));
next unless $authz->{status} eq 'pending';
my $identifier = $authz->{identifier}->{value};
my ($challenge) = grep {$_->{type} eq 'http-01'} @{$authz->{challenges} // []};
die "Missing 'http-01' challenge in server response for '$identifier'\n"
unless defined $challenge;
die "Invalid challenge token ".($challenge->{token} // '')."\n"
# ensure we don't write outside the cwd
unless ($challenge->{token} // '') =~ /\A[A-Za-z0-9_\-]+\z/;
my $keyAuthorization = $challenge->{token}.'.'.$JWK_thumbprint;
# serve $keyAuthorization at http://$domain/.well-known/acme-challenge/$challenge->{token}
if (sysopen(my $fh, $challenge->{token}, O_CREAT|O_EXCL|O_WRONLY, 0644)) {
$fh->print($keyAuthorization);
$fh->close() or die "Can't close: $!";
} elsif ($! == EEXIST) {
print STDERR "WARNING: File exists: $challenge->{token}\n";
} else {
die "Can't open $challenge->{token}: $!";
}
my $r = acme($challenge->{url});
request_json_decode($r);
}
# poll the order URL (to get the status of all challenges at once)
# until the status become 'valid'
my $orderstr = join(', ', map {uc($_->{type}) .":". $_->{value}} @identifiers);
my $certuri;
for (my $i = 0;;) {
my $r = request('GET' => $orderurl);
my $resp = request_json_decode($r);
if (defined (my $problem = $resp->{error})) { # problem document (RFC 7807)
my $msg = $problem->{status};
$msg .= " " .$problem->{title} if defined $problem->{title};
$msg .= " (".$problem->{detail}.")" if defined $problem->{detail};
die $msg, "\n";
}
my $status = $resp->{status};
if (!defined $status or $status eq "invalid") {
die "Error: Invalid order $orderstr\n";
}
elsif ($status eq "ready") {
my $r = acme($order->{finalize}, csr => encode_base64url($csr));
my $resp = request_json_decode($r);
$certuri = $resp->{certificate};
last;
}
elsif ($status eq "valid") {
$certuri = $resp->{certificate} //
die "Error: Missing \"certificate\" field in \"valid\" order\n";
last;
}
elsif ($status ne "pending" and $status ne "processing") {
warn "Unknown order status: $status\n";
}
my $retry_after = request_retry_after($r) // 1;
print STDERR "Retrying after $retry_after seconds...\n";
$i += $retry_after;
die "Timeout exceeded while waiting for challenges to pass ($orderstr)\n"
if $timeout > 0 and $i >= $timeout;
sleep $retry_after;
}
# poll until the cert is available
print STDERR "Certificate URI: $certuri\n";
for (my $i = 0;;) {
$r = request('GET' => $certuri);
die request_status_line($r), "\n" unless $r->is_success();
last unless $r->code == 202; # Accepted
my $retry_after = request_retry_after($r) // 1;
print STDERR "Retrying after $retry_after seconds...\n";
$i += $retry_after;
die "Timeout exceeded while waiting for certificate\n" if $timeout > 0 and $i >= $timeout;
sleep $retry_after;
}
# keep only the leaf certificate
pipe my $rd, my $wd or die "Can't pipe: $!";
my $pid = fork // die "Can't fork: $!";
unless ($pid) {
open STDIN, '<&', $rd or die "Can't dup: $!";
exec qw/openssl x509 -outform PEM/ or die;
}
$rd->close() or die "Can't close: $!";
$wd->print( $r->decoded_content() );
$wd->close() or die "Can't close: $!";
waitpid $pid => 0;
die $? if $? > 0;
}
#############################################################################
# revokeCert
# The certificate to revoke is passed (in DER format) to STDIN; this
# is required since the ACME client might not have read access to the
# X.509 file
#
elsif ($COMMAND eq 'revokeCert') {
die if @ARGV;
my $der = do { local $/ = undef; <STDIN> };
close STDIN or die "Can't close: $!";
# send a KID if the request is signed with the acccount key, otherwise send a JWK
set_kid(0);
my $r = acme_resource('revokeCert', certificate => encode_base64url($der));
exit 0 if $r->is_success();
die request_status_line($r), "\n";
}
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