libcli/smb: add smb2_signing_derivations_fill_const_stack()

This will allow us to have the logic in one place only
in future.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14512

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

2 files changed, 76 insertions, 0 deletions

diff --git a/libcli/smb/smb2_signing.c b/libcli/smb/smb2_signing.c
index e263c29fef5..6e1b50ba49a 100644
--- a/libcli/smb/smb2_signing.c
+++ b/libcli/smb/smb2_signing.c
@@ -34,6 +34,62 @@
 
 #include "lib/crypto/gnutls_helpers.h"
 
+void smb2_signing_derivations_fill_const_stack(struct smb2_signing_derivations *ds,
+					       enum protocol_types protocol,
+					       const DATA_BLOB preauth_hash)
+{
+	*ds = (struct smb2_signing_derivations) { .signing = NULL, };
+
+	if (protocol >= PROTOCOL_SMB3_10) {
+		struct smb2_signing_derivation *d = NULL;
+
+		SMB_ASSERT(preauth_hash.length != 0);
+
+		d = &ds->__signing;
+		ds->signing = d;
+		d->label = data_blob_string_const_null("SMBSigningKey");
+		d->context = preauth_hash;
+
+		d = &ds->__cipher_c2s;
+		ds->cipher_c2s = d;
+		d->label = data_blob_string_const_null("SMBC2SCipherKey");
+		d->context = preauth_hash;
+
+		d = &ds->__cipher_s2c;
+		ds->cipher_s2c = d;
+		d->label = data_blob_string_const_null("SMBS2CCipherKey");
+		d->context = preauth_hash;
+
+		d = &ds->__application;
+		ds->application = d;
+		d->label = data_blob_string_const_null("SMBAppKey");
+		d->context = preauth_hash;
+
+	} else if (protocol >= PROTOCOL_SMB2_24) {
+		struct smb2_signing_derivation *d = NULL;
+
+		d = &ds->__signing;
+		ds->signing = d;
+		d->label = data_blob_string_const_null("SMB2AESCMAC");
+		d->context = data_blob_string_const_null("SmbSign");
+
+		d = &ds->__cipher_c2s;
+		ds->cipher_c2s = d;
+		d->label = data_blob_string_const_null("SMB2AESCCM");
+		d->context = data_blob_string_const_null("ServerIn ");
+
+		d = &ds->__cipher_s2c;
+		ds->cipher_s2c = d;
+		d->label = data_blob_string_const_null("SMB2AESCCM");
+		d->context = data_blob_string_const_null("ServerOut");
+
+		d = &ds->__application;
+		ds->application = d;
+		d->label = data_blob_string_const_null("SMB2APP");
+		d->context = data_blob_string_const_null("SmbRpc");
+	}
+}
+
 int smb2_signing_key_destructor(struct smb2_signing_key *key)
 {
 	if (key->hmac_hnd != NULL) {
diff --git a/libcli/smb/smb2_signing.h b/libcli/smb/smb2_signing.h
index 79989039d50..0a80467717e 100644
--- a/libcli/smb/smb2_signing.h
+++ b/libcli/smb/smb2_signing.h
@@ -23,6 +23,26 @@
 
 struct iovec;
 
+struct smb2_signing_derivation {
+	DATA_BLOB label;
+	DATA_BLOB context;
+};
+
+struct smb2_signing_derivations {
+	struct smb2_signing_derivation __signing;
+	const struct smb2_signing_derivation *signing;
+	struct smb2_signing_derivation __cipher_c2s;
+	const struct smb2_signing_derivation *cipher_c2s;
+	struct smb2_signing_derivation __cipher_s2c;
+	const struct smb2_signing_derivation *cipher_s2c;
+	struct smb2_signing_derivation __application;
+	const struct smb2_signing_derivation *application;
+};
+
+void smb2_signing_derivations_fill_const_stack(struct smb2_signing_derivations *ds,
+					       enum protocol_types protocol,
+					       const DATA_BLOB preauth_hash);
+
 struct smb2_signing_key {
 	DATA_BLOB blob;
 	union {