The Tor Browser: security/nss/cmd/smimetools/smime@141e0f1194b1 (annotated)

security/nss/cmd/smimetools/smime@141e0f1194b1 (annotated)

security/nss/cmd/smimetools/smime

Wed, 31 Dec 2014 07:16:47 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 07:16:47 +0100
branch: TOR_BUG_9701
changeset 3: 141e0f1194b1
permissions: -rwxr-xr-x

Revert simplistic fix pending revisit of Mozilla integration attempt.

 #!/usr/local/bin/perl
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 #
 # smime.pl - frontend for S/MIME message generation and parsing
 #
 use Getopt::Std;
 @boundarychars = ( "0" .. "9", "A" .. "F" );
 # path to cmsutil
 $cmsutilpath = "cmsutil";
 #
 # Thanks to Gisle Aas <gisle@aas.no> for the base64 functions
 # originally taken from MIME-Base64-2.11 at www.cpan.org
 #
 sub encode_base64($)
 {
     my $res = "";
     pos($_[0]) = 0;                          # ensure start at the beginning
     while ($_[0] =~ /(.{1,45})/gs) {
 	$res .= substr(pack('u', $1), 1);    # get rid of length byte after packing
 	chop($res);
     }
     $res =~ tr|` -_|AA-Za-z0-9+/|;
     # fix padding at the end
     my $padding = (3 - length($_[0]) % 3) % 3;
     $res =~ s/.{$padding}$/'=' x $padding/e if $padding;
     # break encoded string into lines of no more than 76 characters each
     $res =~ s/(.{1,76})/$1\n/g;
     $res;
 }
 sub decode_base64($)
 {
     local($^W) = 0; # unpack("u",...) gives bogus warning in 5.00[123]
     my $str = shift;
     my $res = "";
     $str =~ tr|A-Za-z0-9+=/||cd;            # remove non-base64 chars
     if (length($str) % 4) {
 	require Carp;
 	Carp::carp("Length of base64 data not a multiple of 4")
     }
     $str =~ s/=+$//;                        # remove padding
     $str =~ tr|A-Za-z0-9+/| -_|;            # convert to uuencoded format
     while ($str =~ /(.{1,60})/gs) {
 	my $len = chr(32 + length($1)*3/4); # compute length byte
 	$res .= unpack("u", $len . $1 );    # uudecode
     }
     $res;
 }
 #
 # parse headers into a hash
 #
 # %headers = parseheaders($headertext);
 #
 sub parseheaders($)
 {
     my ($headerdata) = @_;
     my $hdr;
     my %hdrhash;
     my $hdrname;
     my $hdrvalue;
     my @hdrvalues;
     my $subhdrname;
     my $subhdrvalue;
     # the expression in split() correctly handles continuation lines
     foreach $hdr (split(/\n(?=\S)/, $headerdata)) {
 	$hdr =~ s/\r*\n\s+/ /g;	# collapse continuation lines
 	($hdrname, $hdrvalue) = $hdr =~ m/^(\S+):\s+(.*)$/;
 	# ignore non-headers (or should we die horribly?)
 	next unless (defined($hdrname));
 	$hdrname =~ tr/A-Z/a-z/;			# lowercase the header name
 	@hdrvalues = split(/\s*;\s*/, $hdrvalue);	# split header values (XXXX quoting)
 	# there is guaranteed to be at least one value
 	$hdrvalue = shift @hdrvalues;
 	if ($hdrvalue =~ /^\s*\"(.*)\"\s*$/) {		# strip quotes if there
 	    $hdrvalue = $1;
 	}
 	$hdrhash{$hdrname}{MAIN} = $hdrvalue;
 	# print "XXX $hdrname = $hdrvalue\n";
 	# deal with additional name-value pairs
 	foreach $hdrvalue (@hdrvalues) {
 	    ($subhdrname, $subhdrvalue) = $hdrvalue =~ m/^(\S+)\s*=\s*(.*)$/;
 	    # ignore non-name-value pairs (or should we die?)
 	    next unless (defined($subhdrname));
 	    $subhdrname =~ tr/A-Z/a-z/;
 	    if ($subhdrvalue =~ /^\s*\"(.*)\"\s*$/) {	# strip quotes if there
 		$subhdrvalue = $1;
 	    }
 	    $hdrhash{$hdrname}{$subhdrname} = $subhdrvalue;
 	}
     }
     return %hdrhash;
 }
 #
 # encryptentity($entity, $options) - encrypt an S/MIME entity,
 #                                    creating a new application/pkcs7-smime entity
 #
 # entity  - string containing entire S/MIME entity to encrypt
 # options - options for cmsutil
 #
 # this will generate and return a new application/pkcs7-smime entity containing
 # the enveloped input entity.
 #
 sub encryptentity($$)
 {
     my ($entity, $cmsutiloptions) = @_;
     my $out = "";
     my $boundary;
     $tmpencfile = "/tmp/encryptentity.$$";
     #
     # generate a random boundary string
     #
     $boundary = "------------ms" . join("", @boundarychars[map{rand @boundarychars }( 1 .. 24 )]);
     #
     # tell cmsutil to generate a enveloped CMS message using our data
     #
     open(CMS, "|$cmsutilpath -E $cmsutiloptions -o $tmpencfile") or die "ERROR: cannot pipe to cmsutil";
     print CMS $entity;
     unless (close(CMS)) {
 	print STDERR "ERROR: encryption failed.\n";
 	unlink($tmpsigfile);
 	exit 1;
     }
     $out  = "Content-Type: application/pkcs7-mime; smime-type=enveloped-data; name=smime.p7m\n";
     $out .= "Content-Transfer-Encoding: base64\n";
     $out .= "Content-Disposition: attachment; filename=smime.p7m\n";
     $out .= "\n";			# end of entity header
     open (ENC, $tmpencfile) or die "ERROR: cannot find newly generated encrypted content";
     local($/) = undef;			# slurp whole file
     $out .= encode_base64(<ENC>), "\n";	# entity body is base64-encoded CMS message
     close(ENC);
     unlink($tmpencfile);
     $out;
 }
 #
 # signentity($entity, $options) - sign an S/MIME entity
 #
 # entity  - string containing entire S/MIME entity to sign
 # options - options for cmsutil
 #
 # this will generate and return a new multipart/signed entity consisting
 # of the canonicalized original content, plus a signature block.
 #
 sub signentity($$)
 {
     my ($entity, $cmsutiloptions) = @_;
     my $out = "";
     my $boundary;
     $tmpsigfile = "/tmp/signentity.$$";
     #
     # generate a random boundary string
     #
     $boundary = "------------ms" . join("", @boundarychars[map{rand @boundarychars }( 1 .. 24 )]);
     #
     # tell cmsutil to generate a signed CMS message using the canonicalized data
     # The signedData has detached content (-T) and includes a signing time attribute (-G)
     #
     # if we do not provide a password on the command line, here's where we would be asked for it
     #
     open(CMS, "|$cmsutilpath -S -T -G $cmsutiloptions -o $tmpsigfile") or die "ERROR: cannot pipe to cmsutil";
     print CMS $entity;
     unless (close(CMS)) {
 	print STDERR "ERROR: signature generation failed.\n";
 	unlink($tmpsigfile);
 	exit 1;
     }
     open (SIG, $tmpsigfile) or die "ERROR: cannot find newly generated signature";
     #
     # construct a new multipart/signed MIME entity consisting of the original content and
     # the signature
     #
     # (we assume that cmsutil generates a SHA1 digest)
     $out .= "Content-Type: multipart/signed; protocol=\"application/pkcs7-signature\"; micalg=sha1; boundary=\"${boundary}\"\n";
     $out .= "\n";		# end of entity header
     $out .= "This is a cryptographically signed message in MIME format.\n"; # explanatory comment
     $out .= "\n--${boundary}\n";
     $out .= $entity;
     $out .= "\n--${boundary}\n";
     $out .= "Content-Type: application/pkcs7-signature; name=smime.p7s\n";
     $out .= "Content-Transfer-Encoding: base64\n";
     $out .= "Content-Disposition: attachment; filename=smime.p7s\n";
     $out .= "Content-Description: S/MIME Cryptographic Signature\n";
     $out .= "\n";		# end of signature subentity header
     local($/) = undef;		# slurp whole file
     $out .= encode_base64(<SIG>);	# append base64-encoded signature
     $out .= "\n--${boundary}--\n";
     close(SIG);
     unlink($tmpsigfile);
     $out;
 }
 sub usage {
     print STDERR "usage: smime [options]\n";
     print STDERR " options:\n";
     print STDERR " -S nick             generate signed message, use certificate named \"nick\"\n";
     print STDERR "  -p passwd          use \"passwd\" as security module password\n";
     print STDERR " -E rec1[,rec2...]   generate encrypted message for recipients\n";
     print STDERR " -D                  decode a S/MIME message\n";
     print STDERR "  -p passwd          use \"passwd\" as security module password\n";
     print STDERR "                     (required for decrypting only)\n";
     print STDERR " -C pathname         set pathname of \"cmsutil\"\n";
     print STDERR " -d directory        set directory containing certificate db\n";
     print STDERR "                     (default: ~/.netscape)\n";
     print STDERR "\nWith -S or -E, smime will take a regular RFC822 message or MIME entity\n";
     print STDERR "on stdin and generate a signed or encrypted S/MIME message with the same\n";
     print STDERR "headers and content from it. The output can be used as input to a MTA.\n";
     print STDERR "-D causes smime to strip off all S/MIME layers if possible and output\n";
     print STDERR "the \"inner\" message.\n";
 }
 #
 # start of main procedures
 #
 #
 # process command line options
 #
 unless (getopts('S:E:p:d:C:D')) {
     usage();
     exit 1;
 }
 unless (defined($opt_S) or defined($opt_E) or defined($opt_D)) {
     print STDERR "ERROR: -S and/or -E, or -D must be specified.\n";
     usage();
     exit 1;
 }
 $signopts = "";
 $encryptopts = "";
 $decodeopts = "";
 # pass -d option along
 if (defined($opt_d)) {
     $signopts .= "-d \"$opt_d\" ";
     $encryptopts .= "-d \"$opt_d\" ";
     $decodeopts .= "-d \"$opt_d\" ";
 }
 if (defined($opt_S)) {
     $signopts .= "-N \"$opt_S\" ";
 }
 if (defined($opt_p)) {
     $signopts .= "-p \"$opt_p\" ";
     $decodeopts .= "-p \"$opt_p\" ";
 }
 if (defined($opt_E)) {
     @recipients = split(",", $opt_E);
     $encryptopts .= "-r ";
     $encryptopts .= join (" -r ", @recipients);
 }
 if (defined($opt_C)) {
     $cmsutilpath = $opt_C;
 }
 #
 # split headers into mime entity headers and RFC822 headers
 # The RFC822 headers are preserved and stay on the outer layer of the message
 #
 $rfc822headers = "";
 $mimeheaders = "";
 $mimebody = "";
 $skippedheaders = "";
 while (<STDIN>) {
     last if (/^$/);
     if (/^content-\S+: /i) {
 	$lastref = \$mimeheaders;
     } elsif (/^mime-version: /i) {
 	$lastref = \$skippedheaders;			# skip it
     } elsif (/^\s/) {
 	;
     } else {
 	$lastref = \$rfc822headers;
     }
     $$lastref .= $_;
 }
 #
 # if there are no MIME entity headers, generate some default ones
 #
 if ($mimeheaders eq "") {
     $mimeheaders .= "Content-Type: text/plain; charset=us-ascii\n";
     $mimeheaders .= "Content-Transfer-Encoding: 7bit\n";
 }
 #
 # slurp in the entity body
 #
 $saveRS = $/;
 $/ = undef;
 $mimebody = <STDIN>;
 $/ = $saveRS;
 chomp($mimebody);
 if (defined $opt_D) {
     #
     # decode
     #
     # possible options would be:
     # - strip off only one layer
     # - strip off outer signature (if present)
     # - just print information about the structure of the message
     # - strip n layers, then dump DER of CMS message
     $layercounter = 1;
     while (1) {
 	%hdrhash = parseheaders($mimeheaders);
 	unless (exists($hdrhash{"content-type"}{MAIN})) {
 	    print STDERR "ERROR: no content type header found in MIME entity\n";
 	    last;	# no content-type - we're done
 	}
 	$contenttype = $hdrhash{"content-type"}{MAIN};
 	if ($contenttype eq "application/pkcs7-mime") {
 	    #
 	    # opaque-signed or enveloped message
 	    #
 	    unless (exists($hdrhash{"content-type"}{"smime-type"})) {
 		print STDERR "ERROR: no smime-type attribute in application/pkcs7-smime entity.\n";
 		last;
 	    }
 	    $smimetype = $hdrhash{"content-type"}{"smime-type"};
 	    if ($smimetype eq "signed-data" or $smimetype eq "enveloped-data") {
 		# it's verification or decryption time!
 		# can handle only base64 encoding for now
 		# all other encodings are treated as binary (8bit)
 		if ($hdrhash{"content-transfer-encoding"}{MAIN} eq "base64") {
 		    $mimebody = decode_base64($mimebody);
 		}
 		# if we need to dump the DER, we would do it right here
 		# now write the DER
 		$tmpderfile = "/tmp/der.$$";
 		open(TMP, ">$tmpderfile") or die "ERROR: cannot write signature data to temporary file";
 		print TMP $mimebody;
 		unless (close(TMP)) {
 		    print STDERR "ERROR: writing signature data to temporary file.\n";
 		    unlink($tmpderfile);
 		    exit 1;
 		}
 		$mimeheaders = "";
 		open(TMP, "$cmsutilpath -D $decodeopts -h $layercounter -i $tmpderfile |") or die "ERROR: cannot open pipe to cmsutil";
 		$layercounter++;
 		while (<TMP>) {
 		    last if (/^\r?$/);			# empty lines mark end of header
 		    if (/^SMIME: /) {			# add all SMIME info to the rfc822 hdrs
 			$lastref = \$rfc822headers;
 		    } elsif (/^\s/) {
 			;				# continuation lines go to the last dest
 		    } else {
 			$lastref = \$mimeheaders;	# all other headers are mime headers
 		    }
 		    $$lastref .= $_;
 		}
 		# slurp in rest of the data to $mimebody
 		$saveRS = $/; $/ = undef; $mimebody = <TMP>; $/ = $saveRS;
 		close(TMP);
 		unlink($tmpderfile);
 	    } else {
 		print STDERR "ERROR: unknown smime-type \"$smimetype\" in application/pkcs7-smime entity.\n";
 		last;
 	    }
 	} elsif ($contenttype eq "multipart/signed") {
 	    #
 	    # clear signed message
 	    #
 	    unless (exists($hdrhash{"content-type"}{"protocol"})) {
 		print STDERR "ERROR: content type has no protocol attribute in multipart/signed entity.\n";
 		last;
 	    }
 	    if ($hdrhash{"content-type"}{"protocol"} ne "application/pkcs7-signature") {
 		# we cannot handle this guy
 		print STDERR "ERROR: unknown protocol \"", $hdrhash{"content-type"}{"protocol"},
 			"\" in multipart/signed entity.\n";
 		last;
 	    }
 	    unless (exists($hdrhash{"content-type"}{"boundary"})) {
 		print STDERR "ERROR: no boundary attribute in multipart/signed entity.\n";
 		last;
 	    }
 	    $boundary = $hdrhash{"content-type"}{"boundary"};
 	    # split $mimebody along \n--$boundary\n - gets you four parts
 	    # first (0), any comments the sending agent might have put in
 	    # second (1), the message itself
 	    # third (2), the signature as a mime entity
 	    # fourth (3), trailing data (there shouldn't be any)
 	    @multiparts = split(/\r?\n--$boundary(?:--)?\r?\n/, $mimebody);
 	    #
 	    # parse the signature headers
 	    ($submimeheaders, $submimebody) = split(/^$/m, $multiparts[2]);
 	    %sighdrhash = parseheaders($submimeheaders);
 	    unless (exists($sighdrhash{"content-type"}{MAIN})) {
 		print STDERR "ERROR: signature entity has no content type.\n";
 		last;
 	    }
 	    if ($sighdrhash{"content-type"}{MAIN} ne "application/pkcs7-signature") {
 		# we cannot handle this guy
 		print STDERR "ERROR: unknown content type \"", $sighdrhash{"content-type"}{MAIN},
 			"\" in signature entity.\n";
 		last;
 	    }
 	    if ($sighdrhash{"content-transfer-encoding"}{MAIN} eq "base64") {
 		$submimebody = decode_base64($submimebody);
 	    }
 	    # we would dump the DER at this point
 	    $tmpsigfile = "/tmp/sig.$$";
 	    open(TMP, ">$tmpsigfile") or die "ERROR: cannot write signature data to temporary file";
 	    print TMP $submimebody;
 	    unless (close(TMP)) {
 		print STDERR "ERROR: writing signature data to temporary file.\n";
 		unlink($tmpsigfile);
 		exit 1;
 	    }
 	    $tmpmsgfile = "/tmp/msg.$$";
 	    open(TMP, ">$tmpmsgfile") or die "ERROR: cannot write message data to temporary file";
 	    print TMP $multiparts[1];
 	    unless (close(TMP)) {
 		print STDERR "ERROR: writing message data to temporary file.\n";
 		unlink($tmpsigfile);
 		unlink($tmpmsgfile);
 		exit 1;
 	    }
 	    $mimeheaders = "";
 	    open(TMP, "$cmsutilpath -D $decodeopts -h $layercounter -c $tmpmsgfile -i $tmpsigfile |") or die "ERROR: cannot open pipe to cmsutil";
 	    $layercounter++;
 	    while (<TMP>) {
 		last if (/^\r?$/);
 		if (/^SMIME: /) {
 		    $lastref = \$rfc822headers;
 		} elsif (/^\s/) {
 		    ;
 		} else {
 		    $lastref = \$mimeheaders;
 		}
 		$$lastref .= $_;
 	    }
 	    $saveRS = $/; $/ = undef; $mimebody = <TMP>; $/ = $saveRS;
 	    close(TMP);
 	    unlink($tmpsigfile);
 	    unlink($tmpmsgfile);
 	} else {
 	    # not a content type we know - we're done
 	    last;
 	}
     }
     # so now we have the S/MIME parsing information in rfc822headers
     # and the first mime entity we could not handle in mimeheaders and mimebody.
     # dump 'em out and we're done.
     print $rfc822headers;
     print $mimeheaders . "\n" . $mimebody;
 } else {
     #
     # encode (which is much easier than decode)
     #
     $mimeentity = $mimeheaders . "\n" . $mimebody;
     #
     # canonicalize inner entity (rudimentary yet)
     # convert single LFs to CRLF
     # if no Content-Transfer-Encoding header present:
     #  if 8 bit chars present, use Content-Transfer-Encoding: quoted-printable
     #  otherwise, use Content-Transfer-Encoding: 7bit
     #
     $mimeentity =~ s/\r*\n/\r\n/mg;
     #
     # now do the wrapping
     # we sign first, then encrypt because that's what Communicator needs
     #
     if (defined($opt_S)) {
 	$mimeentity = signentity($mimeentity, $signopts);
     }
     if (defined($opt_E)) {
 	$mimeentity = encryptentity($mimeentity, $encryptopts);
     }
     #
     # XXX sign again to do triple wrapping (RFC2634)
     #
     #
     # now write out the RFC822 headers
     # followed by the final $mimeentity
     #
     print $rfc822headers;
     print "MIME-Version: 1.0 (NSS SMIME - http://www.mozilla.org/projects/security)\n";	# set up the flag
     print $mimeentity;
 }
 exit 0;

The Tor Browser / annotate

security/nss/cmd/smimetools/smime@141e0f1194b1 (annotated)

security/nss/cmd/smimetools/smime