Commit 3f1e1bea authored by David Howells's avatar David Howells
Browse files

MODSIGN: Use PKCS#7 messages as module signatures 



Move to using PKCS#7 messages as module signatures because:

 (1) We have to be able to support the use of X.509 certificates that don't
     have a subjKeyId set.  We're currently relying on this to look up the
     X.509 certificate in the trusted keyring list.

 (2) PKCS#7 message signed information blocks have a field that supplies the
     data required to match with the X.509 certificate that signed it.

 (3) The PKCS#7 certificate carries fields that specify the digest algorithm
     used to generate the signature in a standardised way and the X.509
     certificates specify the public key algorithm in a standardised way - so
     we don't need our own methods of specifying these.

 (4) We now have PKCS#7 message support in the kernel for signed kexec purposes
     and we can make use of this.

To make this work, the old sign-file script has been replaced with a program
that needs compiling in a previous patch.  The rules to build it are added
here.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Tested-by: default avatarVivek Goyal <vgoyal@redhat.com>
parent bc1c373d

Makefile

+1 −1
Original line number Diff line number Diff line
@@ -873,7 +873,7 @@ ifdef CONFIG_MODULE_SIG_ALL 
MODSECKEY = ./signing_key.priv

MODPUBKEY = ./signing_key.x509

export MODPUBKEY

mod_sign_cmd = perl $(srctree)/scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODSECKEY) $(MODPUBKEY)

mod_sign_cmd = scripts/sign-file $(CONFIG_MODULE_SIG_HASH) $(MODSECKEY) $(MODPUBKEY)

else

mod_sign_cmd = true

endif

init/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -1869,6 +1869,7 @@ config MODULE_SIG 
	select ASN1

	select OID_REGISTRY

	select X509_CERTIFICATE_PARSER

	select PKCS7_MESSAGE_PARSER

	help

	  Check modules for valid signatures upon load: the signature

	  is simply appended to the module. For more information see

kernel/module_signing.c

+44 −176
Original line number Diff line number Diff line
@@ -11,10 +11,9 @@ 


#include <linux/kernel.h>

#include <linux/err.h>

#include <crypto/public_key.h>

#include <crypto/hash.h>

#include <keys/asymmetric-type.h>

#include <keys/system_keyring.h>

#include <crypto/public_key.h>

#include <crypto/pkcs7.h>

#include "module-internal.h"



/*
@@ -28,157 +27,53 @@ 
 *	- Information block

 */

struct module_signature {

	u8	algo;		/* Public-key crypto algorithm [enum pkey_algo] */

	u8	hash;		/* Digest algorithm [enum hash_algo] */

	u8	id_type;	/* Key identifier type [enum pkey_id_type] */

	u8	signer_len;	/* Length of signer's name */

	u8	key_id_len;	/* Length of key identifier */

	u8	algo;		/* Public-key crypto algorithm [0] */

	u8	hash;		/* Digest algorithm [0] */

	u8	id_type;	/* Key identifier type [PKEY_ID_PKCS7] */

	u8	signer_len;	/* Length of signer's name [0] */

	u8	key_id_len;	/* Length of key identifier [0] */

	u8	__pad[3];

	__be32	sig_len;	/* Length of signature data */

};



/*

 * Digest the module contents.

 * Verify a PKCS#7-based signature on a module.

 */

static struct public_key_signature *mod_make_digest(enum hash_algo hash,

						    const void *mod,

						    unsigned long modlen)

static int mod_verify_pkcs7(const void *mod, unsigned long modlen,

			    const void *raw_pkcs7, size_t pkcs7_len)

{

	struct public_key_signature *pks;

	struct crypto_shash *tfm;

	struct shash_desc *desc;

	size_t digest_size, desc_size;

	struct pkcs7_message *pkcs7;

	bool trusted;

	int ret;



	pr_devel("==>%s()\n", __func__);

	

	/* Allocate the hashing algorithm we're going to need and find out how

	 * big the hash operational data will be.

	 */

	tfm = crypto_alloc_shash(hash_algo_name[hash], 0, 0);

	if (IS_ERR(tfm))

		return (PTR_ERR(tfm) == -ENOENT) ? ERR_PTR(-ENOPKG) : ERR_CAST(tfm);



	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);

	digest_size = crypto_shash_digestsize(tfm);



	/* We allocate the hash operational data storage on the end of our

	 * context data and the digest output buffer on the end of that.

	 */

	ret = -ENOMEM;

	pks = kzalloc(digest_size + sizeof(*pks) + desc_size, GFP_KERNEL);

	if (!pks)

		goto error_no_pks;

	pkcs7 = pkcs7_parse_message(raw_pkcs7, pkcs7_len);

	if (IS_ERR(pkcs7))

		return PTR_ERR(pkcs7);



	pks->pkey_hash_algo	= hash;

	pks->digest		= (u8 *)pks + sizeof(*pks) + desc_size;

	pks->digest_size	= digest_size;



	desc = (void *)pks + sizeof(*pks);

	desc->tfm   = tfm;

	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	/* The data should be detached - so we need to supply it. */

	if (pkcs7_supply_detached_data(pkcs7, mod, modlen) < 0) {

		pr_err("PKCS#7 signature with non-detached data\n");

		ret = -EBADMSG;

		goto error;

	}



	ret = crypto_shash_init(desc);

	ret = pkcs7_verify(pkcs7);

	if (ret < 0)

		goto error;



	ret = crypto_shash_finup(desc, mod, modlen, pks->digest);

	ret = pkcs7_validate_trust(pkcs7, system_trusted_keyring, &trusted);

	if (ret < 0)

		goto error;



	crypto_free_shash(tfm);

	pr_devel("<==%s() = ok\n", __func__);

	return pks;

	if (!trusted) {

		pr_err("PKCS#7 signature not signed with a trusted key\n");

		ret = -ENOKEY;

	}



error:

	kfree(pks);

error_no_pks:

	crypto_free_shash(tfm);

	pkcs7_free_message(pkcs7);

	pr_devel("<==%s() = %d\n", __func__, ret);

	return ERR_PTR(ret);

}



/*

 * Extract an MPI array from the signature data.  This represents the actual

 * signature.  Each raw MPI is prefaced by a BE 2-byte value indicating the

 * size of the MPI in bytes.

 *

 * RSA signatures only have one MPI, so currently we only read one.

 */

static int mod_extract_mpi_array(struct public_key_signature *pks,

				 const void *data, size_t len)

{

	size_t nbytes;

	MPI mpi;



	if (len < 3)

		return -EBADMSG;

	nbytes = ((const u8 *)data)[0] << 8 | ((const u8 *)data)[1];

	data += 2;

	len -= 2;

	if (len != nbytes)

		return -EBADMSG;



	mpi = mpi_read_raw_data(data, nbytes);

	if (!mpi)

		return -ENOMEM;

	pks->mpi[0] = mpi;

	pks->nr_mpi = 1;

	return 0;

}



/*

 * Request an asymmetric key.

 */

static struct key *request_asymmetric_key(const char *signer, size_t signer_len,

					  const u8 *key_id, size_t key_id_len)

{

	key_ref_t key;

	size_t i;

	char *id, *q;



	pr_devel("==>%s(,%zu,,%zu)\n", __func__, signer_len, key_id_len);



	/* Construct an identifier. */

	id = kmalloc(signer_len + 2 + key_id_len * 2 + 1, GFP_KERNEL);

	if (!id)

		return ERR_PTR(-ENOKEY);



	memcpy(id, signer, signer_len);



	q = id + signer_len;

	*q++ = ':';

	*q++ = ' ';

	for (i = 0; i < key_id_len; i++) {

		*q++ = hex_asc[*key_id >> 4];

		*q++ = hex_asc[*key_id++ & 0x0f];

	}



	*q = 0;



	pr_debug("Look up: \"%s\"\n", id);



	key = keyring_search(make_key_ref(system_trusted_keyring, 1),

			     &key_type_asymmetric, id);

	if (IS_ERR(key))

		pr_warn("Request for unknown module key '%s' err %ld\n",

			id, PTR_ERR(key));

	kfree(id);



	if (IS_ERR(key)) {

		switch (PTR_ERR(key)) {

			/* Hide some search errors */

		case -EACCES:

		case -ENOTDIR:

		case -EAGAIN:

			return ERR_PTR(-ENOKEY);

		default:

			return ERR_CAST(key);

		}

	}



	pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key_ref_to_ptr(key)));

	return key_ref_to_ptr(key);

	return ret;

}



/*
@@ -186,12 +81,8 @@ static struct key *request_asymmetric_key(const char *signer, size_t signer_len, 
 */

int mod_verify_sig(const void *mod, unsigned long *_modlen)

{

	struct public_key_signature *pks;

	struct module_signature ms;

	struct key *key;

	const void *sig;

	size_t modlen = *_modlen, sig_len;

	int ret;



	pr_devel("==>%s(,%zu)\n", __func__, modlen);
@@ -205,46 +96,23 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen) 
	if (sig_len >= modlen)

		return -EBADMSG;

	modlen -= sig_len;

	if ((size_t)ms.signer_len + ms.key_id_len >= modlen)

		return -EBADMSG;

	modlen -= (size_t)ms.signer_len + ms.key_id_len;



	*_modlen = modlen;

	sig = mod + modlen;



	/* For the moment, only support RSA and X.509 identifiers */

	if (ms.algo != PKEY_ALGO_RSA ||

	    ms.id_type != PKEY_ID_X509)

		return -ENOPKG;



	if (ms.hash >= PKEY_HASH__LAST ||

	    !hash_algo_name[ms.hash])

	if (ms.id_type != PKEY_ID_PKCS7) {

		pr_err("Module is not signed with expected PKCS#7 message\n");

		return -ENOPKG;



	key = request_asymmetric_key(sig, ms.signer_len,

				     sig + ms.signer_len, ms.key_id_len);

	if (IS_ERR(key))

		return PTR_ERR(key);



	pks = mod_make_digest(ms.hash, mod, modlen);

	if (IS_ERR(pks)) {

		ret = PTR_ERR(pks);

		goto error_put_key;

	}



	ret = mod_extract_mpi_array(pks, sig + ms.signer_len + ms.key_id_len,

				    sig_len);

	if (ret < 0)

		goto error_free_pks;



	ret = verify_signature(key, pks);

	pr_devel("verify_signature() = %d\n", ret);

	if (ms.algo != 0 ||

	    ms.hash != 0 ||

	    ms.signer_len != 0 ||

	    ms.key_id_len != 0 ||

	    ms.__pad[0] != 0 ||

	    ms.__pad[1] != 0 ||

	    ms.__pad[2] != 0) {

		pr_err("PKCS#7 signature info has unexpected non-zero params\n");

		return -EBADMSG;

	}



error_free_pks:

	mpi_free(pks->rsa.s);

	kfree(pks);

error_put_key:

	key_put(key);

	pr_devel("<==%s() = %d\n", __func__, ret);

	return ret;	

	return mod_verify_pkcs7(mod, modlen, mod + modlen, sig_len);

}

scripts/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -16,9 +16,11 @@ hostprogs-$(CONFIG_VT) += conmakehash 
hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount

hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable

hostprogs-$(CONFIG_ASN1)	 += asn1_compiler

hostprogs-$(CONFIG_MODULE_SIG)	 += sign-file



HOSTCFLAGS_sortextable.o = -I$(srctree)/tools/include

HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include

HOSTLOADLIBES_sign-file = -lcrypto



always		:= $(hostprogs-y) $(hostprogs-m)

scripts/sign-file

deleted100755 → 0
+0 −421
Original line number Diff line number Diff line 
#!/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;

}

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