ksmbd: disable SMB2_GLOBAL_CAP_ENCRYPTION for SMB 3.1.1

According to the official Microsoft MS-SMB2 document section 3.3.5.4, this
flag should be used only for 3.0 and 3.0.2 dialects. Setting it for 3.1.1
is a violation of the specification.

This causes my Windows 10 client to detect an anomaly in the negotiation,
and disable encryption entirely despite being explicitly enabled in ksmbd,
causing all data transfers to go in plain text.

Fixes: e2f34481b24d ("cifsd: add server-side procedures for SMB3")
Cc: stable@vger.kernel.org # v5.15
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Marcos Del Sol Vives <marcos@orca.pet>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/ksmbd/smb2ops.c b/fs/ksmbd/smb2ops.c
index 0a5d8450e835fa4a804d7f05ab78ce46f41df9f0..02a44d28bdafc2a0d655e78e6d60826816186522 100644 (file)
--- a/fs/ksmbd/smb2ops.c
+++ b/fs/ksmbd/smb2ops.c
@@ -271,9 +271,6 @@ int init_smb3_11_server(struct ksmbd_conn *conn)
        if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB2_LEASES)
                conn->vals->capabilities |= SMB2_GLOBAL_CAP_LEASING;
 
-       if (conn->cipher_type)
-               conn->vals->capabilities |= SMB2_GLOBAL_CAP_ENCRYPTION;
-
        if (server_conf.flags & KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL)
                conn->vals->capabilities |= SMB2_GLOBAL_CAP_MULTI_CHANNEL;
 

diff --git a/fs/ksmbd/smb2pdu.c b/fs/ksmbd/smb2pdu.c
index 125590d5e9402486eff8d2f992cdf811ef3e2183..b8b3a4c28b749a9317d57511aae3a49d5739db8f 100644 (file)
--- a/fs/ksmbd/smb2pdu.c
+++ b/fs/ksmbd/smb2pdu.c
@@ -915,6 +915,25 @@ static void decode_encrypt_ctxt(struct ksmbd_conn *conn,
        }
 }
 
+/**
+ * smb3_encryption_negotiated() - checks if server and client agreed on enabling encryption
+ * @conn:      smb connection
+ *
+ * Return:     true if connection should be encrypted, else false
+ */
+static bool smb3_encryption_negotiated(struct ksmbd_conn *conn)
+{
+       if (!conn->ops->generate_encryptionkey)
+               return false;
+
+       /*
+        * SMB 3.0 and 3.0.2 dialects use the SMB2_GLOBAL_CAP_ENCRYPTION flag.
+        * SMB 3.1.1 uses the cipher_type field.
+        */
+       return (conn->vals->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION) ||
+           conn->cipher_type;
+}
+
 static void decode_compress_ctxt(struct ksmbd_conn *conn,
                                 struct smb2_compression_capabilities_context *pneg_ctxt)
 {
@@ -1469,8 +1488,7 @@ static int ntlm_authenticate(struct ksmbd_work *work)
                    (req->SecurityMode & SMB2_NEGOTIATE_SIGNING_REQUIRED))
                        sess->sign = true;
 
-               if (conn->vals->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION &&
-                   conn->ops->generate_encryptionkey &&
+               if (smb3_encryption_negotiated(conn) &&
                    !(req->Flags & SMB2_SESSION_REQ_FLAG_BINDING)) {
                        rc = conn->ops->generate_encryptionkey(sess);
                        if (rc) {
@@ -1559,8 +1577,7 @@ static int krb5_authenticate(struct ksmbd_work *work)
            (req->SecurityMode & SMB2_NEGOTIATE_SIGNING_REQUIRED))
                sess->sign = true;
 
-       if ((conn->vals->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION) &&
-           conn->ops->generate_encryptionkey) {
+       if (smb3_encryption_negotiated(conn)) {
                retval = conn->ops->generate_encryptionkey(sess);
                if (retval) {
                        ksmbd_debug(SMB,