From 8b5c3ae97f0e30e8df78e81c53b4ba02365a299d Mon Sep 17 00:00:00 2001
From: Andreas Schneider <asn@samba.org>
Date: Fri, 23 Aug 2019 09:12:21 +0200
Subject: [PATCH 137/187] libcli:smb: Use gnutls_aead_cipher_decryptv2() for
 AES GCM or CCM

This is a new call which has been added with GnuTLS 3.6.10 and will
recuduce memory allocations and copying of data.

Signed-off-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Simo Sorce <idra@samba.org>

Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Tue Oct  8 14:12:44 UTC 2019 on sn-devel-184

(cherry picked from commit 4a24d9499757dea377b4e3d8beb7f2c10fd5c5d0)
---
 libcli/smb/smb2_signing.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/libcli/smb/smb2_signing.c b/libcli/smb/smb2_signing.c
index ac0f6f4d29f..166ab9d83ff 100644
--- a/libcli/smb/smb2_signing.c
+++ b/libcli/smb/smb2_signing.c
@@ -588,13 +588,12 @@ NTSTATUS smb2_signing_decrypt_pdu(struct smb2_signing_key *decryption_key,
 {
 	uint8_t *tf;
 	uint16_t flags;
-	int i;
 	size_t a_total;
 	ssize_t m_total;
 	uint32_t msg_size = 0;
 	uint32_t iv_size = 0;
 	uint32_t key_size = 0;
-	uint32_t tag_size = 0;
+	size_t tag_size = 0;
 	uint8_t _key[16] = {0};
 	gnutls_cipher_algorithm_t algo = 0;
 	gnutls_datum_t key;
@@ -680,12 +679,37 @@ NTSTATUS smb2_signing_decrypt_pdu(struct smb2_signing_key *decryption_key,
 		}
 	}
 
+#ifdef HAVE_GNUTLS_AEAD_CIPHER_ENCRYPTV2
+	{
+		giovec_t auth_iov[1];
+
+		auth_iov[0] = (giovec_t) {
+			.iov_base = tf + SMB2_TF_NONCE,
+			.iov_len  = a_total,
+		};
+
+		rc = gnutls_aead_cipher_decryptv2(decryption_key->cipher_hnd,
+						  iv.data,
+						  iv.size,
+						  auth_iov,
+						  1,
+						  &vector[1],
+						  count - 1,
+						  tf + SMB2_TF_SIGNATURE,
+						  tag_size);
+		if (rc < 0) {
+			status = gnutls_error_to_ntstatus(rc, NT_STATUS_INTERNAL_ERROR);
+			goto out;
+		}
+	}
+#else /* HAVE_GNUTLS_AEAD_CIPHER_ENCRYPTV2 */
 	{
 		size_t ctext_size = m_total + tag_size;
 		uint8_t *ctext = NULL;
 		size_t ptext_size = m_total;
 		uint8_t *ptext = NULL;
 		size_t len = 0;
+		int i;
 
 		/* GnuTLS doesn't have a iovec API for decryption yet */
 
@@ -751,6 +775,7 @@ NTSTATUS smb2_signing_decrypt_pdu(struct smb2_signing_key *decryption_key,
 		TALLOC_FREE(ptext);
 		TALLOC_FREE(ctext);
 	}
+#endif /* HAVE_GNUTLS_AEAD_CIPHER_ENCRYPTV2 */
 
 	DBG_INFO("Decrypted SMB2 message\n");
 
-- 
2.23.0