4 smb3 server fixes, all also for stable

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Merge tag '6.2-rc5-ksmbd-server-fixes' of git://git.samba.org/ksmbd

Pull ksmbd server fixes from Steve French:
 "Four smb3 server fixes, all also for stable:

   - fix for signing bug

   - fix to more strictly check packet length

   - add a max connections parm to limit simultaneous connections

   - fix error message flood that can occur with newer Samba xattr
     format"

* tag '6.2-rc5-ksmbd-server-fixes' of git://git.samba.org/ksmbd:
  ksmbd: downgrade ndr version error message to debug
  ksmbd: limit pdu length size according to connection status
  ksmbd: do not sign response to session request for guest login
  ksmbd: add max connections parameter

fs/ksmbd/connection.c

@@ -280,7 +280,7 @@ int ksmbd_conn_handler_loop(void *p)
 {
 	struct ksmbd_conn *conn = (struct ksmbd_conn *)p;
 	struct ksmbd_transport *t = conn->transport;
-	unsigned int pdu_size;
+	unsigned int pdu_size, max_allowed_pdu_size;
 	char hdr_buf[4] = {0,};
 	int size;
 
@@ -305,13 +305,26 @@ int ksmbd_conn_handler_loop(void *p)
 		pdu_size = get_rfc1002_len(hdr_buf);
 		ksmbd_debug(CONN, "RFC1002 header %u bytes\n", pdu_size);
 
+		if (conn->status == KSMBD_SESS_GOOD)
+			max_allowed_pdu_size =
+				SMB3_MAX_MSGSIZE + conn->vals->max_write_size;
+		else
+			max_allowed_pdu_size = SMB3_MAX_MSGSIZE;
+
+		if (pdu_size > max_allowed_pdu_size) {
+			pr_err_ratelimited("PDU length(%u) excceed maximum allowed pdu size(%u) on connection(%d)\n",
+					pdu_size, max_allowed_pdu_size,
+					conn->status);
+			break;
+		}
+
 		/*
 		 * Check if pdu size is valid (min : smb header size,
 		 * max : 0x00FFFFFF).
 		 */
 		if (pdu_size < __SMB2_HEADER_STRUCTURE_SIZE ||
 		    pdu_size > MAX_STREAM_PROT_LEN) {
-			continue;
+			break;
 		}
 
 		/* 4 for rfc1002 length field */

fs/ksmbd/ksmbd_netlink.h

@@ -106,7 +106,8 @@ struct ksmbd_startup_request {
 	__u32	sub_auth[3];		/* Subauth value for Security ID */
 	__u32	smb2_max_credits;	/* MAX credits */
 	__u32	smbd_max_io_size;	/* smbd read write size */
-	__u32	reserved[127];		/* Reserved room */
+	__u32	max_connections;	/* Number of maximum simultaneous connections */
+	__u32	reserved[126];		/* Reserved room */
 	__u32	ifc_list_sz;		/* interfaces list size */
 	__s8	____payload[];
 };

fs/ksmbd/ndr.c

@@ -242,7 +242,7 @@ int ndr_decode_dos_attr(struct ndr *n, struct xattr_dos_attrib *da)
 		return ret;
 
 	if (da->version != 3 && da->version != 4) {
-		pr_err("v%d version is not supported\n", da->version);
+		ksmbd_debug(VFS, "v%d version is not supported\n", da->version);
 		return -EINVAL;
 	}
 
@@ -251,7 +251,7 @@ int ndr_decode_dos_attr(struct ndr *n, struct xattr_dos_attrib *da)
 		return ret;
 
 	if (da->version != version2) {
-		pr_err("ndr version mismatched(version: %d, version2: %d)\n",
+		ksmbd_debug(VFS, "ndr version mismatched(version: %d, version2: %d)\n",
 		       da->version, version2);
 		return -EINVAL;
 	}
@@ -457,7 +457,7 @@ int ndr_decode_v4_ntacl(struct ndr *n, struct xattr_ntacl *acl)
 	if (ret)
 		return ret;
 	if (acl->version != 4) {
-		pr_err("v%d version is not supported\n", acl->version);
+		ksmbd_debug(VFS, "v%d version is not supported\n", acl->version);
 		return -EINVAL;
 	}
 
@@ -465,7 +465,7 @@ int ndr_decode_v4_ntacl(struct ndr *n, struct xattr_ntacl *acl)
 	if (ret)
 		return ret;
 	if (acl->version != version2) {
-		pr_err("ndr version mismatched(version: %d, version2: %d)\n",
+		ksmbd_debug(VFS, "ndr version mismatched(version: %d, version2: %d)\n",
 		       acl->version, version2);
 		return -EINVAL;
 	}

fs/ksmbd/server.h

@@ -41,6 +41,7 @@ struct ksmbd_server_config {
 	unsigned int		share_fake_fscaps;
 	struct smb_sid		domain_sid;
 	unsigned int		auth_mechs;
+	unsigned int		max_connections;
 
 	char			*conf[SERVER_CONF_WORK_GROUP + 1];
 };

fs/ksmbd/smb2pdu.c

@@ -8663,6 +8663,7 @@ int smb3_decrypt_req(struct ksmbd_work *work)
 bool smb3_11_final_sess_setup_resp(struct ksmbd_work *work)
 {
 	struct ksmbd_conn *conn = work->conn;
+	struct ksmbd_session *sess = work->sess;
 	struct smb2_hdr *rsp = smb2_get_msg(work->response_buf);
 
 	if (conn->dialect < SMB30_PROT_ID)
@@ -8672,6 +8673,7 @@ bool smb3_11_final_sess_setup_resp(struct ksmbd_work *work)
 		rsp = ksmbd_resp_buf_next(work);
 
 	if (le16_to_cpu(rsp->Command) == SMB2_SESSION_SETUP_HE &&
+	    sess->user && !user_guest(sess->user) &&
 	    rsp->Status == STATUS_SUCCESS)
 		return true;
 	return false;

fs/ksmbd/smb2pdu.h

@@ -26,6 +26,7 @@
 #define SMB3_DEFAULT_TRANS_SIZE	(1024 * 1024)
 #define SMB3_MIN_IOSIZE		(64 * 1024)
 #define SMB3_MAX_IOSIZE		(8 * 1024 * 1024)
+#define SMB3_MAX_MSGSIZE	(4 * 4096)
 
 /*
  *	Definitions for SMB2 Protocol Data Units (network frames)

fs/ksmbd/transport_ipc.c

@@ -308,6 +308,9 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req)
 	if (req->smbd_max_io_size)
 		init_smbd_max_io_size(req->smbd_max_io_size);
 
+	if (req->max_connections)
+		server_conf.max_connections = req->max_connections;
+
 	ret = ksmbd_set_netbios_name(req->netbios_name);
 	ret |= ksmbd_set_server_string(req->server_string);
 	ret |= ksmbd_set_work_group(req->work_group);

fs/ksmbd/transport_tcp.c

@@ -15,6 +15,8 @@
 #define IFACE_STATE_DOWN		BIT(0)
 #define IFACE_STATE_CONFIGURED		BIT(1)
 
+static atomic_t active_num_conn;
+
 struct interface {
 	struct task_struct	*ksmbd_kthread;
 	struct socket		*ksmbd_socket;
@@ -185,8 +187,10 @@ static int ksmbd_tcp_new_connection(struct socket *client_sk)
 	struct tcp_transport *t;
 
 	t = alloc_transport(client_sk);
-	if (!t)
+	if (!t) {
+		sock_release(client_sk);
 		return -ENOMEM;
+	}
 
 	csin = KSMBD_TCP_PEER_SOCKADDR(KSMBD_TRANS(t)->conn);
 	if (kernel_getpeername(client_sk, csin) < 0) {
@@ -239,6 +243,15 @@ static int ksmbd_kthread_fn(void *p)
 			continue;
 		}
 
+		if (server_conf.max_connections &&
+		    atomic_inc_return(&active_num_conn) >= server_conf.max_connections) {
+			pr_info_ratelimited("Limit the maximum number of connections(%u)\n",
+					    atomic_read(&active_num_conn));
+			atomic_dec(&active_num_conn);
+			sock_release(client_sk);
+			continue;
+		}
+
 		ksmbd_debug(CONN, "connect success: accepted new connection\n");
 		client_sk->sk->sk_rcvtimeo = KSMBD_TCP_RECV_TIMEOUT;
 		client_sk->sk->sk_sndtimeo = KSMBD_TCP_SEND_TIMEOUT;
@@ -368,6 +381,8 @@ static int ksmbd_tcp_writev(struct ksmbd_transport *t, struct kvec *iov,
 static void ksmbd_tcp_disconnect(struct ksmbd_transport *t)
 {
 	free_transport(TCP_TRANS(t));
+	if (server_conf.max_connections)
+		atomic_dec(&active_num_conn);
 }
 
 static void tcp_destroy_socket(struct socket *ksmbd_socket)