diff options
Diffstat (limited to 'kernel/scripts/sign-file')
| -rwxr-xr-x | kernel/scripts/sign-file | 421 |
1 files changed, 421 insertions, 0 deletions
diff --git a/kernel/scripts/sign-file b/kernel/scripts/sign-file new file mode 100755 index 000000000..3906ee1e2 --- /dev/null +++ b/kernel/scripts/sign-file @@ -0,0 +1,421 @@ +#!/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($signature), "\n"; + print "Size of information : ", length($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; +} |