#!/usr/bin/perl -w # # Sign a module file using the given key. # my $USAGE = "Usage: scripts/sign-file [-v] <hash algo> <key> <x509> <module> [<dest>]\n" . " scripts/sign-file [-v] -s <raw sig> <hash algo> <x509> <module> [<dest>]\n"; use strict; use FileHandle; use IPC::Open2; use Getopt::Std; my %opts; getopts('vs:', \%opts) or die $USAGE; my $verbose = $opts{'v'}; my $signature_file = $opts{'s'}; die $USAGE if ($#ARGV > 4); die $USAGE if (!$signature_file && $#ARGV < 3 || $signature_file && $#ARGV < 2); my $dgst = shift @ARGV; my $private_key; if (!$signature_file) { $private_key = shift @ARGV; } my $x509 = shift @ARGV; my $module = shift @ARGV; my ($dest, $keep_orig); if (@ARGV) { $dest = $ARGV[0]; $keep_orig = 1; } else { $dest = $module . "~"; } die "Can't read private key\n" if (!$signature_file && !-r $private_key); die "Can't read signature file\n" if ($signature_file && !-r $signature_file); die "Can't read X.509 certificate\n" unless (-r $x509); die "Can't read module\n" unless (-r $module); # # Function to read the contents of a file into a variable. # sub read_file($) { my ($file) = @_; my $contents; my $len; open(FD, "<$file") || die $file; binmode FD; my @st = stat(FD); die $file if (!@st); $len = read(FD, $contents, $st[7]) || die $file; close(FD) || die $file; die "$file: Wanted length ", $st[7], ", got ", $len, "\n" if ($len != $st[7]); return $contents; } ############################################################################### # # First of all, we have to parse the X.509 certificate to find certain details # about it. # # We read the DER-encoded X509 certificate and parse it to extract the Subject # name and Subject Key Identifier. Theis provides the data we need to build # the certificate identifier. # # The signer's name part of the identifier is fabricated from the commonName, # the organizationName or the emailAddress components of the X.509 subject # name. # # The subject key ID is used to select which of that signer's certificates # we're intending to use to sign the module. # ############################################################################### my $x509_certificate = read_file($x509); my $UNIV = 0 << 6; my $APPL = 1 << 6; my $CONT = 2 << 6; my $PRIV = 3 << 6; my $CONS = 0x20; my $BOOLEAN = 0x01; my $INTEGER = 0x02; my $BIT_STRING = 0x03; my $OCTET_STRING = 0x04; my $NULL = 0x05; my $OBJ_ID = 0x06; my $UTF8String = 0x0c; my $SEQUENCE = 0x10; my $SET = 0x11; my $UTCTime = 0x17; my $GeneralizedTime = 0x18; my %OIDs = ( pack("CCC", 85, 4, 3) => "commonName", pack("CCC", 85, 4, 6) => "countryName", pack("CCC", 85, 4, 10) => "organizationName", pack("CCC", 85, 4, 11) => "organizationUnitName", pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 1, 1) => "rsaEncryption", pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 1, 5) => "sha1WithRSAEncryption", pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 9, 1) => "emailAddress", pack("CCC", 85, 29, 35) => "authorityKeyIdentifier", pack("CCC", 85, 29, 14) => "subjectKeyIdentifier", pack("CCC", 85, 29, 19) => "basicConstraints" ); ############################################################################### # # Extract an ASN.1 element from a string and return information about it. # ############################################################################### sub asn1_extract($$@) { my ($cursor, $expected_tag, $optional) = @_; return [ -1 ] if ($cursor->[1] == 0 && $optional); die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (elem ", $cursor->[1], ")\n" if ($cursor->[1] < 2); my ($tag, $len) = unpack("CC", substr(${$cursor->[2]}, $cursor->[0], 2)); if ($expected_tag != -1 && $tag != $expected_tag) { return [ -1 ] if ($optional); die $x509, ": ", $cursor->[0], ": ASN.1 unexpected tag (", $tag, " not ", $expected_tag, ")\n"; } $cursor->[0] += 2; $cursor->[1] -= 2; die $x509, ": ", $cursor->[0], ": ASN.1 long tag\n" if (($tag & 0x1f) == 0x1f); die $x509, ": ", $cursor->[0], ": ASN.1 indefinite length\n" if ($len == 0x80); if ($len > 0x80) { my $l = $len - 0x80; die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (len len $l)\n" if ($cursor->[1] < $l); if ($l == 0x1) { $len = unpack("C", substr(${$cursor->[2]}, $cursor->[0], 1)); } elsif ($l == 0x2) { $len = unpack("n", substr(${$cursor->[2]}, $cursor->[0], 2)); } elsif ($l == 0x3) { $len = unpack("C", substr(${$cursor->[2]}, $cursor->[0], 1)) << 16; $len = unpack("n", substr(${$cursor->[2]}, $cursor->[0] + 1, 2)); } elsif ($l == 0x4) { $len = unpack("N", substr(${$cursor->[2]}, $cursor->[0], 4)); } else { die $x509, ": ", $cursor->[0], ": ASN.1 element too long (", $l, ")\n"; } $cursor->[0] += $l; $cursor->[1] -= $l; } die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (", $len, ")\n" if ($cursor->[1] < $len); my $ret = [ $tag, [ $cursor->[0], $len, $cursor->[2] ] ]; $cursor->[0] += $len; $cursor->[1] -= $len; return $ret; } ############################################################################### # # Retrieve the data referred to by a cursor # ############################################################################### sub asn1_retrieve($) { my ($cursor) = @_; my ($offset, $len, $data) = @$cursor; return substr($$data, $offset, $len); } ############################################################################### # # Roughly parse the X.509 certificate # ############################################################################### my $cursor = [ 0, length($x509_certificate), \$x509_certificate ]; my $cert = asn1_extract($cursor, $UNIV | $CONS | $SEQUENCE); my $tbs = asn1_extract($cert->[1], $UNIV | $CONS | $SEQUENCE); my $version = asn1_extract($tbs->[1], $CONT | $CONS | 0, 1); my $serial_number = asn1_extract($tbs->[1], $UNIV | $INTEGER); my $sig_type = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE); my $issuer = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE); my $validity = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE); my $subject = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE); my $key = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE); my $issuer_uid = asn1_extract($tbs->[1], $CONT | $CONS | 1, 1); my $subject_uid = asn1_extract($tbs->[1], $CONT | $CONS | 2, 1); my $extension_list = asn1_extract($tbs->[1], $CONT | $CONS | 3, 1); my $subject_key_id = (); my $authority_key_id = (); # # Parse the extension list # if ($extension_list->[0] != -1) { my $extensions = asn1_extract($extension_list->[1], $UNIV | $CONS | $SEQUENCE); while ($extensions->[1]->[1] > 0) { my $ext = asn1_extract($extensions->[1], $UNIV | $CONS | $SEQUENCE); my $x_oid = asn1_extract($ext->[1], $UNIV | $OBJ_ID); my $x_crit = asn1_extract($ext->[1], $UNIV | $BOOLEAN, 1); my $x_val = asn1_extract($ext->[1], $UNIV | $OCTET_STRING); my $raw_oid = asn1_retrieve($x_oid->[1]); next if (!exists($OIDs{$raw_oid})); my $x_type = $OIDs{$raw_oid}; my $raw_value = asn1_retrieve($x_val->[1]); if ($x_type eq "subjectKeyIdentifier") { my $vcursor = [ 0, length($raw_value), \$raw_value ]; $subject_key_id = asn1_extract($vcursor, $UNIV | $OCTET_STRING); } } } ############################################################################### # # Determine what we're going to use as the signer's name. In order of # preference, take one of: commonName, organizationName or emailAddress. # ############################################################################### my $org = ""; my $cn = ""; my $email = ""; while ($subject->[1]->[1] > 0) { my $rdn = asn1_extract($subject->[1], $UNIV | $CONS | $SET); my $attr = asn1_extract($rdn->[1], $UNIV | $CONS | $SEQUENCE); my $n_oid = asn1_extract($attr->[1], $UNIV | $OBJ_ID); my $n_val = asn1_extract($attr->[1], -1); my $raw_oid = asn1_retrieve($n_oid->[1]); next if (!exists($OIDs{$raw_oid})); my $n_type = $OIDs{$raw_oid}; my $raw_value = asn1_retrieve($n_val->[1]); if ($n_type eq "organizationName") { $org = $raw_value; } elsif ($n_type eq "commonName") { $cn = $raw_value; } elsif ($n_type eq "emailAddress") { $email = $raw_value; } } my $signers_name = $email; if ($org && $cn) { # Don't use the organizationName if the commonName repeats it if (length($org) <= length($cn) && substr($cn, 0, length($org)) eq $org) { $signers_name = $cn; goto got_id_name; } # Or a signifcant chunk of it if (length($org) >= 7 && length($cn) >= 7 && substr($cn, 0, 7) eq substr($org, 0, 7)) { $signers_name = $cn; goto got_id_name; } $signers_name = $org . ": " . $cn; } elsif ($org) { $signers_name = $org; } elsif ($cn) { $signers_name = $cn; } got_id_name: die $x509, ": ", "X.509: Couldn't find the Subject Key Identifier extension\n" if (!$subject_key_id); my $key_identifier = asn1_retrieve($subject_key_id->[1]); ############################################################################### # # Create and attach the module signature # ############################################################################### # # Signature parameters # my $algo = 1; # Public-key crypto algorithm: RSA my $hash = 0; # Digest algorithm my $id_type = 1; # Identifier type: X.509 # # Digest the data # my $prologue; if ($dgst eq "sha1") { $prologue = pack("C*", 0x30, 0x21, 0x30, 0x09, 0x06, 0x05, 0x2B, 0x0E, 0x03, 0x02, 0x1A, 0x05, 0x00, 0x04, 0x14); $hash = 2; } elsif ($dgst eq "sha224") { $prologue = pack("C*", 0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04, 0x05, 0x00, 0x04, 0x1C); $hash = 7; } elsif ($dgst eq "sha256") { $prologue = pack("C*", 0x30, 0x31, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, 0x05, 0x00, 0x04, 0x20); $hash = 4; } elsif ($dgst eq "sha384") { $prologue = pack("C*", 0x30, 0x41, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02, 0x05, 0x00, 0x04, 0x30); $hash = 5; } elsif ($dgst eq "sha512") { $prologue = pack("C*", 0x30, 0x51, 0x30, 0x0d, 0x06, 0x09, 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, 0x05, 0x00, 0x04, 0x40); $hash = 6; } else { die "Unknown hash algorithm: $dgst\n"; } my $signature; if ($signature_file) { $signature = read_file($signature_file); } else { # # Generate the digest and read from openssl's stdout # my $digest; $digest = readpipe("openssl dgst -$dgst -binary $module") || die "openssl dgst"; # # Generate the binary signature, which will be just the integer that # comprises the signature with no metadata attached. # my $pid; $pid = open2(*read_from, *write_to, "openssl rsautl -sign -inkey $private_key -keyform PEM") || die "openssl rsautl"; binmode write_to; print write_to $prologue . $digest || die "pipe to openssl rsautl"; close(write_to) || die "pipe to openssl rsautl"; binmode read_from; read(read_from, $signature, 4096) || die "pipe from openssl rsautl"; close(read_from) || die "pipe from openssl rsautl"; waitpid($pid, 0) || die; die "openssl rsautl died: $?" if ($? >> 8); } $signature = pack("n", length($signature)) . $signature, # # Build the signed binary # my $unsigned_module = read_file($module); my $magic_number = "~Module signature appended~\n"; my $info = pack("CCCCCxxxN", $algo, $hash, $id_type, length($signers_name), length($key_identifier), length($signature)); if ($verbose) { print "Size of unsigned module: ", length($unsigned_module), "\n"; print "Size of signer's name : ", length($signers_name), "\n"; print "Size of key identifier : ", length($key_identifier), "\n"; print "Size of signature : ", length($signature), "\n"; print "Size of informaton : ", length($info), "\n"; print "Size of magic number : ", length($magic_number), "\n"; print "Signer's name : '", $signers_name, "'\n"; print "Digest : $dgst\n"; } open(FD, ">$dest") || die $dest; binmode FD; print FD $unsigned_module, $signers_name, $key_identifier, $signature, $info, $magic_number ; close FD || die $dest; if (!$keep_orig) { rename($dest, $module) || die $module; }