[PATCH] libkmod-signature: use PKCS7 for LibreSSL or older OpenSSL

[Stefan Strogin <stefan.strogin@gmail.com>]

Linux kernel uses either PKCS #7 or CMS signing modules (scripts/sign-file.c).
CMS is not supported by LibreSSL, PKCS #7 is used instead.
For now modinfo used CMS with no altenative requiring >=openssl-1.1.0
built with CMS support.

Use PKCS #7 for parsing module signature information when CMS is not available.

Signed-off-by: Stefan Strogin <stefan.strogin@gmail.com>
---
 libkmod/libkmod-signature.c | 78 +++++++++++++++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 3 deletions(-)

diff --git a/libkmod/libkmod-signature.c b/libkmod/libkmod-signature.c
index 48d0145..aa2a60e 100644
--- a/libkmod/libkmod-signature.c
+++ b/libkmod/libkmod-signature.c
@@ -20,9 +20,16 @@
 #include <endian.h>
 #include <inttypes.h>
 #ifdef ENABLE_OPENSSL
-#include <openssl/cms.h>
-#include <openssl/ssl.h>
-#endif
+# include <openssl/ssl.h>
+# if defined(LIBRESSL_VERSION_NUMBER) || \
+	OPENSSL_VERSION_NUMBER < 0x10100000L || \
+	defined(OPENSSL_NO_CMS)
+#  define USE_PKCS7
+#  include <openssl/pkcs7.h>
+# else
+#  include <openssl/cms.h>
+# endif /* LIBRESSL_VERSION_NUMBER */
+#endif /* ENABLE_OPENSSL */
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -122,7 +129,11 @@ static bool fill_default(const char *mem, off_t size,
 #ifdef ENABLE_OPENSSL
 
 struct pkcs7_private {
+#ifndef USE_PKCS7
 	CMS_ContentInfo *cms;
+#else
+	PKCS7 *pkcs7;
+#endif
 	unsigned char *key_id;
 	BIGNUM *sno;
 };
@@ -132,7 +143,11 @@ static void pkcs7_free(void *s)
 	struct kmod_signature_info *si = s;
 	struct pkcs7_private *pvt = si->private;
 
+#ifndef USE_PKCS7
 	CMS_ContentInfo_free(pvt->cms);
+#else
+	PKCS7_free(pvt->pkcs7);
+#endif
 	BN_free(pvt->sno);
 	free(pvt->key_id);
 	free(pvt);
@@ -187,7 +202,13 @@ static const char *x509_name_to_str(X509_NAME *name)
 		return NULL;
 
 	d = X509_NAME_ENTRY_get_data(e);
+#if (defined(LIBRESSL_VERSION_NUMBER) && \
+		LIBRESSL_VERSION_NUMBER < 0x20700000L) || \
+	OPENSSL_VERSION_NUMBER < 0x10100000L
+	str = (const char *)ASN1_STRING_data(d);
+#else
 	str = (const char *)ASN1_STRING_get0_data(d);
+#endif
 
 	return str;
 }
@@ -197,11 +218,18 @@ static bool fill_pkcs7(const char *mem, off_t size,
 		       struct kmod_signature_info *sig_info)
 {
 	const char *pkcs7_raw;
+#ifndef USE_PKCS7
 	CMS_ContentInfo *cms;
 	STACK_OF(CMS_SignerInfo) *sis;
 	CMS_SignerInfo *si;
 	int rc;
 	ASN1_OCTET_STRING *key_id;
+#else
+	PKCS7 *pkcs7;
+	STACK_OF(PKCS7_SIGNER_INFO) *sis;
+	PKCS7_SIGNER_INFO *si;
+	PKCS7_ISSUER_AND_SERIAL *is;
+#endif
 	X509_NAME *issuer;
 	ASN1_INTEGER *sno;
 	ASN1_OCTET_STRING *sig;
@@ -220,14 +248,23 @@ static bool fill_pkcs7(const char *mem, off_t size,
 
 	in = BIO_new_mem_buf(pkcs7_raw, sig_len);
 
+#ifndef USE_PKCS7
 	cms = d2i_CMS_bio(in, NULL);
 	if (cms == NULL) {
 		BIO_free(in);
 		return false;
 	}
+#else
+	pkcs7 = d2i_PKCS7_bio(in, NULL);
+	if (pkcs7 == NULL) {
+		BIO_free(in);
+		return false;
+	}
+#endif
 
 	BIO_free(in);
 
+#ifndef USE_PKCS7
 	sis = CMS_get0_SignerInfos(cms);
 	if (sis == NULL)
 		goto err;
@@ -245,8 +282,35 @@ static bool fill_pkcs7(const char *mem, off_t size,
 		goto err;
 
 	CMS_SignerInfo_get0_algs(si, NULL, NULL, &dig_alg, &sig_alg);
+#else
+	sis = PKCS7_get_signer_info(pkcs7);
+	if (sis == NULL)
+		goto err;
+
+	si = sk_PKCS7_SIGNER_INFO_value(sis, 0);
+	if (si == NULL)
+		goto err;
+
+	is = si->issuer_and_serial;
+	if (is == NULL)
+		goto err;
+	issuer = is->issuer;
+	sno = is->serial;
+
+	sig = si->enc_digest;
+	if (sig == NULL)
+		goto err;
+
+	PKCS7_SIGNER_INFO_get0_algs(si, NULL, &dig_alg, &sig_alg);
+#endif
 
+#if (defined(LIBRESSL_VERSION_NUMBER) && \
+		LIBRESSL_VERSION_NUMBER < 0x20700000L) || \
+	OPENSSL_VERSION_NUMBER < 0x10100000L
+	sig_info->sig = (const char *)ASN1_STRING_data(sig);
+#else
 	sig_info->sig = (const char *)ASN1_STRING_get0_data(sig);
+#endif
 	sig_info->sig_len = ASN1_STRING_length(sig);
 
 	sno_bn = ASN1_INTEGER_to_BN(sno, NULL);
@@ -277,7 +341,11 @@ static bool fill_pkcs7(const char *mem, off_t size,
 	if (pvt == NULL)
 		goto err3;
 
+#ifndef USE_PKCS7
 	pvt->cms = cms;
+#else
+	pvt->pkcs7 = pkcs7;
+#endif
 	pvt->key_id = key_id_str;
 	pvt->sno = sno_bn;
 	sig_info->private = pvt;
@@ -290,7 +358,11 @@ err3:
 err2:
 	BN_free(sno_bn);
 err:
+#ifndef USE_PKCS7
 	CMS_ContentInfo_free(cms);
+#else
+	PKCS7_free(pkcs7);
+#endif
 	return false;
 }
 
-- 
2.20.1