linux/scripts/sign-file
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   1#!/usr/bin/perl -w
   2#
   3# Sign a module file using the given key.
   4#
   5
   6my $USAGE =
   7"Usage: scripts/sign-file [-v] <hash algo> <key> <x509> <module> [<dest>]\n" .
   8"       scripts/sign-file [-v] -s <raw sig> <hash algo> <x509> <module> [<dest>]\n";
   9
  10use strict;
  11use FileHandle;
  12use IPC::Open2;
  13use Getopt::Std;
  14
  15my %opts;
  16getopts('vs:', \%opts) or die $USAGE;
  17my $verbose = $opts{'v'};
  18my $signature_file = $opts{'s'};
  19
  20die $USAGE if ($#ARGV > 4);
  21die $USAGE if (!$signature_file && $#ARGV < 3 || $signature_file && $#ARGV < 2);
  22
  23my $dgst = shift @ARGV;
  24my $private_key;
  25if (!$signature_file) {
  26        $private_key = shift @ARGV;
  27}
  28my $x509 = shift @ARGV;
  29my $module = shift @ARGV;
  30my ($dest, $keep_orig);
  31if (@ARGV) {
  32        $dest = $ARGV[0];
  33        $keep_orig = 1;
  34} else {
  35        $dest = $module . "~";
  36}
  37
  38die "Can't read private key\n" if (!$signature_file && !-r $private_key);
  39die "Can't read signature file\n" if ($signature_file && !-r $signature_file);
  40die "Can't read X.509 certificate\n" unless (-r $x509);
  41die "Can't read module\n" unless (-r $module);
  42
  43#
  44# Function to read the contents of a file into a variable.
  45#
  46sub read_file($)
  47{
  48    my ($file) = @_;
  49    my $contents;
  50    my $len;
  51
  52    open(FD, "<$file") || die $file;
  53    binmode FD;
  54    my @st = stat(FD);
  55    die $file if (!@st);
  56    $len = read(FD, $contents, $st[7]) || die $file;
  57    close(FD) || die $file;
  58    die "$file: Wanted length ", $st[7], ", got ", $len, "\n"
  59        if ($len != $st[7]);
  60    return $contents;
  61}
  62
  63###############################################################################
  64#
  65# First of all, we have to parse the X.509 certificate to find certain details
  66# about it.
  67#
  68# We read the DER-encoded X509 certificate and parse it to extract the Subject
  69# name and Subject Key Identifier.  Theis provides the data we need to build
  70# the certificate identifier.
  71#
  72# The signer's name part of the identifier is fabricated from the commonName,
  73# the organizationName or the emailAddress components of the X.509 subject
  74# name.
  75#
  76# The subject key ID is used to select which of that signer's certificates
  77# we're intending to use to sign the module.
  78#
  79###############################################################################
  80my $x509_certificate = read_file($x509);
  81
  82my $UNIV = 0 << 6;
  83my $APPL = 1 << 6;
  84my $CONT = 2 << 6;
  85my $PRIV = 3 << 6;
  86
  87my $CONS = 0x20;
  88
  89my $BOOLEAN     = 0x01;
  90my $INTEGER     = 0x02;
  91my $BIT_STRING  = 0x03;
  92my $OCTET_STRING = 0x04;
  93my $NULL        = 0x05;
  94my $OBJ_ID      = 0x06;
  95my $UTF8String  = 0x0c;
  96my $SEQUENCE    = 0x10;
  97my $SET         = 0x11;
  98my $UTCTime     = 0x17;
  99my $GeneralizedTime = 0x18;
 100
 101my %OIDs = (
 102    pack("CCC", 85, 4, 3)       => "commonName",
 103    pack("CCC", 85, 4, 6)       => "countryName",
 104    pack("CCC", 85, 4, 10)      => "organizationName",
 105    pack("CCC", 85, 4, 11)      => "organizationUnitName",
 106    pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 1, 1) => "rsaEncryption",
 107    pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 1, 5) => "sha1WithRSAEncryption",
 108    pack("CCCCCCCCC", 42, 134, 72, 134, 247, 13, 1, 9, 1) => "emailAddress",
 109    pack("CCC", 85, 29, 35)     => "authorityKeyIdentifier",
 110    pack("CCC", 85, 29, 14)     => "subjectKeyIdentifier",
 111    pack("CCC", 85, 29, 19)     => "basicConstraints"
 112);
 113
 114###############################################################################
 115#
 116# Extract an ASN.1 element from a string and return information about it.
 117#
 118###############################################################################
 119sub asn1_extract($$@)
 120{
 121    my ($cursor, $expected_tag, $optional) = @_;
 122
 123    return [ -1 ]
 124        if ($cursor->[1] == 0 && $optional);
 125
 126    die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (elem ", $cursor->[1], ")\n"
 127        if ($cursor->[1] < 2);
 128
 129    my ($tag, $len) = unpack("CC", substr(${$cursor->[2]}, $cursor->[0], 2));
 130
 131    if ($expected_tag != -1 && $tag != $expected_tag) {
 132        return [ -1 ]
 133            if ($optional);
 134        die $x509, ": ", $cursor->[0], ": ASN.1 unexpected tag (", $tag,
 135        " not ", $expected_tag, ")\n";
 136    }
 137
 138    $cursor->[0] += 2;
 139    $cursor->[1] -= 2;
 140
 141    die $x509, ": ", $cursor->[0], ": ASN.1 long tag\n"
 142        if (($tag & 0x1f) == 0x1f);
 143    die $x509, ": ", $cursor->[0], ": ASN.1 indefinite length\n"
 144        if ($len == 0x80);
 145
 146    if ($len > 0x80) {
 147        my $l = $len - 0x80;
 148        die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (len len $l)\n"
 149            if ($cursor->[1] < $l);
 150
 151        if ($l == 0x1) {
 152            $len = unpack("C", substr(${$cursor->[2]}, $cursor->[0], 1));
 153        } elsif ($l == 0x2) {
 154            $len = unpack("n", substr(${$cursor->[2]}, $cursor->[0], 2));
 155        } elsif ($l == 0x3) {
 156            $len = unpack("C", substr(${$cursor->[2]}, $cursor->[0], 1)) << 16;
 157            $len = unpack("n", substr(${$cursor->[2]}, $cursor->[0] + 1, 2));
 158        } elsif ($l == 0x4) {
 159            $len = unpack("N", substr(${$cursor->[2]}, $cursor->[0], 4));
 160        } else {
 161            die $x509, ": ", $cursor->[0], ": ASN.1 element too long (", $l, ")\n";
 162        }
 163
 164        $cursor->[0] += $l;
 165        $cursor->[1] -= $l;
 166    }
 167
 168    die $x509, ": ", $cursor->[0], ": ASN.1 data underrun (", $len, ")\n"
 169        if ($cursor->[1] < $len);
 170
 171    my $ret = [ $tag, [ $cursor->[0], $len, $cursor->[2] ] ];
 172    $cursor->[0] += $len;
 173    $cursor->[1] -= $len;
 174
 175    return $ret;
 176}
 177
 178###############################################################################
 179#
 180# Retrieve the data referred to by a cursor
 181#
 182###############################################################################
 183sub asn1_retrieve($)
 184{
 185    my ($cursor) = @_;
 186    my ($offset, $len, $data) = @$cursor;
 187    return substr($$data, $offset, $len);
 188}
 189
 190###############################################################################
 191#
 192# Roughly parse the X.509 certificate
 193#
 194###############################################################################
 195my $cursor = [ 0, length($x509_certificate), \$x509_certificate ];
 196
 197my $cert = asn1_extract($cursor, $UNIV | $CONS | $SEQUENCE);
 198my $tbs = asn1_extract($cert->[1], $UNIV | $CONS | $SEQUENCE);
 199my $version = asn1_extract($tbs->[1], $CONT | $CONS | 0, 1);
 200my $serial_number = asn1_extract($tbs->[1], $UNIV | $INTEGER);
 201my $sig_type = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 202my $issuer = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 203my $validity = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 204my $subject = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 205my $key = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 206my $issuer_uid = asn1_extract($tbs->[1], $CONT | $CONS | 1, 1);
 207my $subject_uid = asn1_extract($tbs->[1], $CONT | $CONS | 2, 1);
 208my $extension_list = asn1_extract($tbs->[1], $CONT | $CONS | 3, 1);
 209
 210my $subject_key_id = ();
 211my $authority_key_id = ();
 212
 213#
 214# Parse the extension list
 215#
 216if ($extension_list->[0] != -1) {
 217    my $extensions = asn1_extract($extension_list->[1], $UNIV | $CONS | $SEQUENCE);
 218
 219    while ($extensions->[1]->[1] > 0) {
 220        my $ext = asn1_extract($extensions->[1], $UNIV | $CONS | $SEQUENCE);
 221        my $x_oid = asn1_extract($ext->[1], $UNIV | $OBJ_ID);
 222        my $x_crit = asn1_extract($ext->[1], $UNIV | $BOOLEAN, 1);
 223        my $x_val = asn1_extract($ext->[1], $UNIV | $OCTET_STRING);
 224
 225        my $raw_oid = asn1_retrieve($x_oid->[1]);
 226        next if (!exists($OIDs{$raw_oid}));
 227        my $x_type = $OIDs{$raw_oid};
 228
 229        my $raw_value = asn1_retrieve($x_val->[1]);
 230
 231        if ($x_type eq "subjectKeyIdentifier") {
 232            my $vcursor = [ 0, length($raw_value), \$raw_value ];
 233
 234            $subject_key_id = asn1_extract($vcursor, $UNIV | $OCTET_STRING);
 235        }
 236    }
 237}
 238
 239###############################################################################
 240#
 241# Determine what we're going to use as the signer's name.  In order of
 242# preference, take one of: commonName, organizationName or emailAddress.
 243#
 244###############################################################################
 245my $org = "";
 246my $cn = "";
 247my $email = "";
 248
 249while ($subject->[1]->[1] > 0) {
 250    my $rdn = asn1_extract($subject->[1], $UNIV | $CONS | $SET);
 251    my $attr = asn1_extract($rdn->[1], $UNIV | $CONS | $SEQUENCE);
 252    my $n_oid = asn1_extract($attr->[1], $UNIV | $OBJ_ID);
 253    my $n_val = asn1_extract($attr->[1], -1);
 254
 255    my $raw_oid = asn1_retrieve($n_oid->[1]);
 256    next if (!exists($OIDs{$raw_oid}));
 257    my $n_type = $OIDs{$raw_oid};
 258
 259    my $raw_value = asn1_retrieve($n_val->[1]);
 260
 261    if ($n_type eq "organizationName") {
 262        $org = $raw_value;
 263    } elsif ($n_type eq "commonName") {
 264        $cn = $raw_value;
 265    } elsif ($n_type eq "emailAddress") {
 266        $email = $raw_value;
 267    }
 268}
 269
 270my $signers_name = $email;
 271
 272if ($org && $cn) {
 273    # Don't use the organizationName if the commonName repeats it
 274    if (length($org) <= length($cn) &&
 275        substr($cn, 0, length($org)) eq $org) {
 276        $signers_name = $cn;
 277        goto got_id_name;
 278    }
 279
 280    # Or a signifcant chunk of it
 281    if (length($org) >= 7 &&
 282        length($cn) >= 7 &&
 283        substr($cn, 0, 7) eq substr($org, 0, 7)) {
 284        $signers_name = $cn;
 285        goto got_id_name;
 286    }
 287
 288    $signers_name = $org . ": " . $cn;
 289} elsif ($org) {
 290    $signers_name = $org;
 291} elsif ($cn) {
 292    $signers_name = $cn;
 293}
 294
 295got_id_name:
 296
 297die $x509, ": ", "X.509: Couldn't find the Subject Key Identifier extension\n"
 298    if (!$subject_key_id);
 299
 300my $key_identifier = asn1_retrieve($subject_key_id->[1]);
 301
 302###############################################################################
 303#
 304# Create and attach the module signature
 305#
 306###############################################################################
 307
 308#
 309# Signature parameters
 310#
 311my $algo = 1;           # Public-key crypto algorithm: RSA
 312my $hash = 0;           # Digest algorithm
 313my $id_type = 1;        # Identifier type: X.509
 314
 315#
 316# Digest the data
 317#
 318my $prologue;
 319if ($dgst eq "sha1") {
 320    $prologue = pack("C*",
 321                     0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
 322                     0x2B, 0x0E, 0x03, 0x02, 0x1A,
 323                     0x05, 0x00, 0x04, 0x14);
 324    $hash = 2;
 325} elsif ($dgst eq "sha224") {
 326    $prologue = pack("C*",
 327                     0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
 328                     0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
 329                     0x05, 0x00, 0x04, 0x1C);
 330    $hash = 7;
 331} elsif ($dgst eq "sha256") {
 332    $prologue = pack("C*",
 333                     0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
 334                     0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
 335                     0x05, 0x00, 0x04, 0x20);
 336    $hash = 4;
 337} elsif ($dgst eq "sha384") {
 338    $prologue = pack("C*",
 339                     0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
 340                     0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
 341                     0x05, 0x00, 0x04, 0x30);
 342    $hash = 5;
 343} elsif ($dgst eq "sha512") {
 344    $prologue = pack("C*",
 345                     0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
 346                     0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
 347                     0x05, 0x00, 0x04, 0x40);
 348    $hash = 6;
 349} else {
 350    die "Unknown hash algorithm: $dgst\n";
 351}
 352
 353my $signature;
 354if ($signature_file) {
 355        $signature = read_file($signature_file);
 356} else {
 357        #
 358        # Generate the digest and read from openssl's stdout
 359        #
 360        my $digest;
 361        $digest = readpipe("openssl dgst -$dgst -binary $module") || die "openssl dgst";
 362
 363        #
 364        # Generate the binary signature, which will be just the integer that
 365        # comprises the signature with no metadata attached.
 366        #
 367        my $pid;
 368        $pid = open2(*read_from, *write_to,
 369                     "openssl rsautl -sign -inkey $private_key -keyform PEM") ||
 370            die "openssl rsautl";
 371        binmode write_to;
 372        print write_to $prologue . $digest || die "pipe to openssl rsautl";
 373        close(write_to) || die "pipe to openssl rsautl";
 374
 375        binmode read_from;
 376        read(read_from, $signature, 4096) || die "pipe from openssl rsautl";
 377        close(read_from) || die "pipe from openssl rsautl";
 378        waitpid($pid, 0) || die;
 379        die "openssl rsautl died: $?" if ($? >> 8);
 380}
 381$signature = pack("n", length($signature)) . $signature,
 382
 383#
 384# Build the signed binary
 385#
 386my $unsigned_module = read_file($module);
 387
 388my $magic_number = "~Module signature appended~\n";
 389
 390my $info = pack("CCCCCxxxN",
 391                $algo, $hash, $id_type,
 392                length($signers_name),
 393                length($key_identifier),
 394                length($signature));
 395
 396if ($verbose) {
 397    print "Size of unsigned module: ", length($unsigned_module), "\n";
 398    print "Size of signer's name  : ", length($signers_name), "\n";
 399    print "Size of key identifier : ", length($key_identifier), "\n";
 400    print "Size of signature      : ", length($signature), "\n";
 401    print "Size of informaton     : ", length($info), "\n";
 402    print "Size of magic number   : ", length($magic_number), "\n";
 403    print "Signer's name          : '", $signers_name, "'\n";
 404    print "Digest                 : $dgst\n";
 405}
 406
 407open(FD, ">$dest") || die $dest;
 408binmode FD;
 409print FD
 410    $unsigned_module,
 411    $signers_name,
 412    $key_identifier,
 413    $signature,
 414    $info,
 415    $magic_number
 416    ;
 417close FD || die $dest;
 418
 419if (!$keep_orig) {
 420    rename($dest, $module) || die $module;
 421}
 422
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