Root/scripts/sign-file

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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