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Commit ed8c2076 authored by David Howells's avatar David Howells
Browse files

sign-file: Generate CMS message as signature instead of PKCS#7 



Make sign-file use the OpenSSL CMS routines to generate a message to be
used as the signature blob instead of the PKCS#7 routines.  This allows us
to change how the matching X.509 certificate is selected.  With PKCS#7 the
only option is to match on the serial number and issuer fields of an X.509
certificate; with CMS, we also have the option of matching by subjectKeyId
extension.  The new behaviour is selected with the "-k" flag.

Without the -k flag specified, the output is pretty much identical to the
PKCS#7 output.

Whilst we're at it, don't include the S/MIME capability list in the message
as it's irrelevant to us.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-By: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 60d65cac

scripts/sign-file.c

+27 −24
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
#include <openssl/bio.h>

#include <openssl/evp.h>

#include <openssl/pem.h>

#include <openssl/pkcs7.h>

#include <openssl/cms.h>

#include <openssl/err.h>

#include <openssl/engine.h>
@@ -107,13 +107,14 @@ int main(int argc, char **argv) 
	struct module_signature sig_info = { .id_type = PKEY_ID_PKCS7 };

	char *hash_algo = NULL;

	char *private_key_name, *x509_name, *module_name, *dest_name;

	bool save_pkcs7 = false, replace_orig;

	bool save_cms = false, replace_orig;

	bool sign_only = false;

	unsigned char buf[4096];

	unsigned long module_size, pkcs7_size;

	unsigned long module_size, cms_size;

	unsigned int use_keyid = 0;

	const EVP_MD *digest_algo;

	EVP_PKEY *private_key;

	PKCS7 *pkcs7;

	CMS_ContentInfo *cms;

	X509 *x509;

	BIO *b, *bd = NULL, *bm;

	int opt, n;
@@ -125,10 +126,11 @@ int main(int argc, char **argv) 
	key_pass = getenv("KBUILD_SIGN_PIN");



	do {

		opt = getopt(argc, argv, "dp");

		opt = getopt(argc, argv, "dpk");

		switch (opt) {

		case 'p': save_pkcs7 = true; break;

		case 'd': sign_only = true; save_pkcs7 = true; break;

		case 'p': save_cms = true; break;

		case 'd': sign_only = true; save_cms = true; break;

		case 'k': use_keyid = CMS_USE_KEYID; break;

		case -1: break;

		default: format();

		}
@@ -208,23 +210,24 @@ int main(int argc, char **argv) 
	bm = BIO_new_file(module_name, "rb");

	ERR(!bm, "%s", module_name);



	/* Load the PKCS#7 message from the digest buffer. */

	pkcs7 = PKCS7_sign(NULL, NULL, NULL, NULL,

			   PKCS7_NOCERTS | PKCS7_PARTIAL | PKCS7_BINARY | PKCS7_DETACHED | PKCS7_STREAM);

	ERR(!pkcs7, "PKCS7_sign");

	/* Load the CMS message from the digest buffer. */

	cms = CMS_sign(NULL, NULL, NULL, NULL,

		       CMS_NOCERTS | CMS_PARTIAL | CMS_BINARY | CMS_DETACHED | CMS_STREAM);

	ERR(!cms, "CMS_sign");



	ERR(!PKCS7_sign_add_signer(pkcs7, x509, private_key, digest_algo, PKCS7_NOCERTS | PKCS7_BINARY),

	    "PKCS7_sign_add_signer");

	ERR(PKCS7_final(pkcs7, bm, PKCS7_NOCERTS | PKCS7_BINARY) < 0,

	    "PKCS7_final");

	ERR(!CMS_add1_signer(cms, x509, private_key, digest_algo,

			     CMS_NOCERTS | CMS_BINARY | CMS_NOSMIMECAP | use_keyid),

	    "CMS_sign_add_signer");

	ERR(CMS_final(cms, bm, NULL, CMS_NOCERTS | CMS_BINARY) < 0,

	    "CMS_final");



	if (save_pkcs7) {

		char *pkcs7_name;

	if (save_cms) {

		char *cms_name;



		ERR(asprintf(&pkcs7_name, "%s.pkcs7", module_name) < 0, "asprintf");

		b = BIO_new_file(pkcs7_name, "wb");

		ERR(!b, "%s", pkcs7_name);

		ERR(i2d_PKCS7_bio_stream(b, pkcs7, NULL, 0) < 0, "%s", pkcs7_name);

		ERR(asprintf(&cms_name, "%s.p7s", module_name) < 0, "asprintf");

		b = BIO_new_file(cms_name, "wb");

		ERR(!b, "%s", cms_name);

		ERR(i2d_CMS_bio_stream(b, cms, NULL, 0) < 0, "%s", cms_name);

		BIO_free(b);

	}
@@ -240,9 +243,9 @@ int main(int argc, char **argv) 
	ERR(n < 0, "%s", module_name);

	module_size = BIO_number_written(bd);



	ERR(i2d_PKCS7_bio_stream(bd, pkcs7, NULL, 0) < 0, "%s", dest_name);

	pkcs7_size = BIO_number_written(bd) - module_size;

	sig_info.sig_len = htonl(pkcs7_size);

	ERR(i2d_CMS_bio_stream(bd, cms, NULL, 0) < 0, "%s", dest_name);

	cms_size = BIO_number_written(bd) - module_size;

	sig_info.sig_len = htonl(cms_size);

	ERR(BIO_write(bd, &sig_info, sizeof(sig_info)) < 0, "%s", dest_name);

	ERR(BIO_write(bd, magic_number, sizeof(magic_number) - 1) < 0, "%s", dest_name);