winbind Backtrace if NSS_STATUS_UNAVAIL

[Jeremy Allison]

On Mon, Sep 19, 2005 at 04:26:31PM +0200, Ingo Steuwer wrote:
> Hi
> 
> I've had a problem on a Memberserver where Samba 3.0.20 gives an Backtrace in 
> log.smbd[0] after there were problems in the communication with the Samba-PDC 
> in this network. 
> 
> The Backtrace itself is a result of recursive calls of 
> winbindd_request_response in wb_common.c. If the result is 
> "NT_STATUS_UNAVAIL" it loops to wait for a connection (up to 10 times) and 
> calls winbindd_send_request, which calls through write_sock and 
> winbind_open_pipe_sock again winbindd_request_response. This ends up in 
> arbitrary deep recursions.

Ok - can you try this patch please ? I'll check into 3.0 and HEAD
so please let me know if this fixes your problems.

Thanks,

	Jeremy.
-------------- next part --------------
Index: nsswitch/winbindd_nss.h
===================================================================
--- nsswitch/winbindd_nss.h	(revision 10320)
+++ nsswitch/winbindd_nss.h	(working copy)
@@ -172,6 +172,8 @@
 
 /* This is a flag that can only be sent from parent to child */
 #define WBFLAG_IS_PRIVILEGED            0x0400
+/* Flag to say this is a winbindd internal send - don't recurse. */
+#define WBFLAG_RECURSE			0x0800
 
 /* Winbind request structure */
 
Index: nsswitch/winbind_client.h
===================================================================
--- nsswitch/winbind_client.h	(revision 10320)
+++ nsswitch/winbind_client.h	(working copy)
@@ -8,8 +8,7 @@
 NSS_STATUS winbindd_request_response(int req_type, 
 			    struct winbindd_request *request,
 			    struct winbindd_response *response);
-int winbind_open_pipe_sock(void);
-int write_sock(void *buffer, int count);
+int write_sock(void *buffer, int count, int recursing);
 int read_reply(struct winbindd_response *response);
 void close_sock(void);
 void free_response(struct winbindd_response *response);
Index: nsswitch/wb_common.c
===================================================================
--- nsswitch/wb_common.c	(revision 10320)
+++ nsswitch/wb_common.c	(working copy)
@@ -284,7 +284,7 @@
 
 /* Connect to winbindd socket */
 
-int winbind_open_pipe_sock(void)
+static int winbind_open_pipe_sock(int recursing)
 {
 #ifdef HAVE_UNIXSOCKET
 	static pid_t our_pid;
@@ -302,12 +302,17 @@
 		return winbindd_fd;
 	}
 
+	if (recursing) {
+		return -1;
+	}
+
 	if ((winbindd_fd = winbind_named_pipe_sock(WINBINDD_SOCKET_DIR)) == -1) {
 		return -1;
 	}
 
 	/* version-check the socket */
 
+	request.flags = WBFLAG_RECURSE;
 	if ((winbindd_request_response(WINBINDD_INTERFACE_VERSION, &request, &response) != NSS_STATUS_SUCCESS) || (response.data.interface_version != WINBIND_INTERFACE_VERSION)) {
 		close_sock();
 		return -1;
@@ -315,6 +320,7 @@
 
 	/* try and get priv pipe */
 
+	request.flags = WBFLAG_RECURSE;
 	if (winbindd_request_response(WINBINDD_PRIV_PIPE_DIR, &request, &response) == NSS_STATUS_SUCCESS) {
 		int fd;
 		if ((fd = winbind_named_pipe_sock(response.extra_data)) != -1) {
@@ -333,7 +339,7 @@
 
 /* Write data to winbindd socket */
 
-int write_sock(void *buffer, int count)
+int write_sock(void *buffer, int count, int recursing)
 {
 	int result, nwritten;
 	
@@ -341,7 +347,7 @@
 	
  restart:
 	
-	if (winbind_open_pipe_sock() == -1) {
+	if (winbind_open_pipe_sock(recursing) == -1) {
 		return -1;
 	}
 	
@@ -534,7 +540,7 @@
 
 	init_request(request, req_type);
 	
-	if (write_sock(request, sizeof(*request)) == -1) {
+	if (write_sock(request, sizeof(*request), request->flags & WBFLAG_RECURSE) == -1) {
 		return NSS_STATUS_UNAVAIL;
 	}
 	
Index: nsswitch/pam_winbind.c
===================================================================
--- nsswitch/pam_winbind.c	(revision 10320)
+++ nsswitch/pam_winbind.c	(working copy)
@@ -106,7 +106,7 @@
 	/* Fill in request and send down pipe */
 	init_request(request, req_type);
 	
-	if (write_sock(request, sizeof(*request)) == -1) {
+	if (write_sock(request, sizeof(*request), 0) == -1) {
 		_pam_log(LOG_ERR, "write to socket failed!");
 		close_sock();
 		return PAM_SERVICE_ERR;