scripts/sign-file

   1 #!/usr/bin/perl -w
   2 #
   3 # Sign a module file using the given key.
   4 #
   5
   6 my $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
  10 use strict;
  11 use FileHandle;
  12 use IPC::Open2;
  13 use Getopt::Std;
  14
  15 my %opts;
  16 getopts('vs:', \%opts) or die $USAGE;
  17 my $verbose = $opts{'v'};
  18 my $signature_file = $opts{'s'};
  19
  20 die $USAGE if ($#ARGV > 4);
  21 die $USAGE if (!$signature_file && $#ARGV < 3 || $signature_file && $#ARGV < 2);
  22
  23 my $dgst = shift @ARGV;
  24 my $private_key;
  25 if (!$signature_file) {
  26         $private_key = shift @ARGV;
  27 }
  28 my $x509 = shift @ARGV;
  29 my $module = shift @ARGV;
  30 my ($dest, $keep_orig);
  31 if (@ARGV) {
  32         $dest = $ARGV[0];
  33         $keep_orig = 1;
  34 } else {
  35         $dest = $module . "~";
  36 }
  37
  38 die "Can't read private key\n" if (!$signature_file && !-r $private_key);
  39 die "Can't read signature file\n" if ($signature_file && !-r $signature_file);
  40 die "Can't read X.509 certificate\n" unless (-r $x509);
  41 die "Can't read module\n" unless (-r $module);
  42
  43 #
  44 # Function to read the contents of a file into a variable.
  45 #
  46 sub read_file($)
  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 ###############################################################################
  80 my $x509_certificate = read_file($x509);
  81
  82 my $UNIV = 0 << 6;
  83 my $APPL = 1 << 6;
  84 my $CONT = 2 << 6;
  85 my $PRIV = 3 << 6;
  86
  87 my $CONS = 0x20;
  88
  89 my $BOOLEAN     = 0x01;
  90 my $INTEGER     = 0x02;
  91 my $BIT_STRING  = 0x03;
  92 my $OCTET_STRING = 0x04;
  93 my $NULL        = 0x05;
  94 my $OBJ_ID      = 0x06;
  95 my $UTF8String  = 0x0c;
  96 my $SEQUENCE    = 0x10;
  97 my $SET         = 0x11;
  98 my $UTCTime     = 0x17;
  99 my $GeneralizedTime = 0x18;
 100
 101 my %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 ###############################################################################
 119 sub 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 ###############################################################################
 183 sub 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 ###############################################################################
 195 my $cursor = [ 0, length($x509_certificate), \$x509_certificate ];
 196
 197 my $cert = asn1_extract($cursor, $UNIV | $CONS | $SEQUENCE);
 198 my $tbs = asn1_extract($cert->[1], $UNIV | $CONS | $SEQUENCE);
 199 my $version = asn1_extract($tbs->[1], $CONT | $CONS | 0, 1);
 200 my $serial_number = asn1_extract($tbs->[1], $UNIV | $INTEGER);
 201 my $sig_type = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 202 my $issuer = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 203 my $validity = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 204 my $subject = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 205 my $key = asn1_extract($tbs->[1], $UNIV | $CONS | $SEQUENCE);
 206 my $issuer_uid = asn1_extract($tbs->[1], $CONT | $CONS | 1, 1);
 207 my $subject_uid = asn1_extract($tbs->[1], $CONT | $CONS | 2, 1);
 208 my $extension_list = asn1_extract($tbs->[1], $CONT | $CONS | 3, 1);
 209
 210 my $subject_key_id = ();
 211 my $authority_key_id = ();
 212
 213 #
 214 # Parse the extension list
 215 #
 216 if ($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 ###############################################################################
 245 my $org = "";
 246 my $cn = "";
 247 my $email = "";
 248
 249 while ($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
 270 my $signers_name = $email;
 271
 272 if ($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
 295 got_id_name:
 296
 297 die $x509, ": ", "X.509: Couldn't find the Subject Key Identifier extension\n"
 298     if (!$subject_key_id);
 299
 300 my $key_identifier = asn1_retrieve($subject_key_id->[1]);
 301
 302 ###############################################################################
 303 #
 304 # Create and attach the module signature
 305 #
 306 ###############################################################################
 307
 308 #
 309 # Signature parameters
 310 #
 311 my $algo = 1;           # Public-key crypto algorithm: RSA
 312 my $hash = 0;           # Digest algorithm
 313 my $id_type = 1;        # Identifier type: X.509
 314
 315 #
 316 # Digest the data
 317 #
 318 my $prologue;
 319 if ($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
 353 my $signature;
 354 if ($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 #
 386 my $unsigned_module = read_file($module);
 387
 388 my $magic_number = "~Module signature appended~\n";
 389
 390 my $info = pack("CCCCCxxxN",
 391                 $algo, $hash, $id_type,
 392                 length($signers_name),
 393                 length($key_identifier),
 394                 length($signature));
 395
 396 if ($verbose) {
 397     print "Size of unsigned module: ", length($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($signature), "\n";
 401     print "Size of information    : ", length($info), "\n";
 402     print "Size of magic number   : ", length($magic_number), "\n";
 403     print "Signer's name          : '", $signers_name, "'\n";
 404     print "Digest                 : $dgst\n";
 405 }
 406
 407 open(FD, ">$dest") || die $dest;
 408 binmode FD;
 409 print FD
 410     $unsigned_module,
 411     $signers_name,
 412     $key_identifier,
 413     $signature,
 414     $info,
 415     $magic_number
 416     ;
 417 close FD || die $dest;
 418
 419 if (!$keep_orig) {
 420     rename($dest, $module) || die $module;
 421 }