SMB3.1.1: Add GCM crypto to the encrypt and decrypt functions

SMB3.1.1 GCM performs much better than the older CCM default:
more than twice as fast in the write patch (copy to the Samba
server on localhost for example) and 80% faster on the read
patch (copy from the server).

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/smb2ops.c

@@ -3367,7 +3367,7 @@ smb2_dir_needs_close(struct cifsFileInfo *cfile)
 
 static void
 fill_transform_hdr(struct smb2_transform_hdr *tr_hdr, unsigned int orig_len,
-		   struct smb_rqst *old_rq)
+		   struct smb_rqst *old_rq, __le16 cipher_type)
 {
 	struct smb2_sync_hdr *shdr =
 			(struct smb2_sync_hdr *)old_rq->rq_iov[0].iov_base;
@@ -3376,7 +3376,10 @@ fill_transform_hdr(struct smb2_transform_hdr *tr_hdr, unsigned int orig_len,
 	tr_hdr->ProtocolId = SMB2_TRANSFORM_PROTO_NUM;
 	tr_hdr->OriginalMessageSize = cpu_to_le32(orig_len);
 	tr_hdr->Flags = cpu_to_le16(0x01);
-	get_random_bytes(&tr_hdr->Nonce, SMB3_AES128CCM_NONCE);
+	if (cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+		get_random_bytes(&tr_hdr->Nonce, SMB3_AES128GCM_NONCE);
+	else
+		get_random_bytes(&tr_hdr->Nonce, SMB3_AES128CCM_NONCE);
 	memcpy(&tr_hdr->SessionId, &shdr->SessionId, 8);
 }
 
@@ -3534,8 +3537,13 @@ crypt_message(struct TCP_Server_Info *server, int num_rqst,
 		rc = -ENOMEM;
 		goto free_sg;
 	}
-	iv[0] = 3;
-	memcpy(iv + 1, (char *)tr_hdr->Nonce, SMB3_AES128CCM_NONCE);
+
+	if (server->cipher_type == SMB2_ENCRYPTION_AES128_GCM)
+		memcpy(iv, (char *)tr_hdr->Nonce, SMB3_AES128GCM_NONCE);
+	else {
+		iv[0] = 3;
+		memcpy(iv + 1, (char *)tr_hdr->Nonce, SMB3_AES128CCM_NONCE);
+	}
 
 	aead_request_set_crypt(req, sg, sg, crypt_len, iv);
 	aead_request_set_ad(req, assoc_data_len);
@@ -3635,7 +3643,7 @@ smb3_init_transform_rq(struct TCP_Server_Info *server, int num_rqst,
 	}
 
 	/* fill the 1st iov with a transform header */
-	fill_transform_hdr(tr_hdr, orig_len, old_rq);
+	fill_transform_hdr(tr_hdr, orig_len, old_rq, server->cipher_type);
 
 	rc = crypt_message(server, num_rqst, new_rq, 1);
 	cifs_dbg(FYI, "Encrypt message returned %d\n", rc);