Use a separate tdb for mutexes

Another preparation to convert secrets.c to dbwrap: The dbwrap API does not
provide a sane tdb_lock_with_timeout abstraction. In the clustered case the DC
mutex is needed per-node anyway, so it is perfectly fine to use a local mutex
only.
(This used to be commit f94a63cd8f94490780ad9331da229c0bcb2ca5d6)

7 files changed, 71 insertions, 82 deletions

diff --git a/source3/auth/auth_domain.c b/source3/auth/auth_domain.c
index df51966f4c..26474089fb 100644
--- a/source3/auth/auth_domain.c
+++ b/source3/auth/auth_domain.c
@@ -24,6 +24,7 @@
 #define DBGC_CLASS DBGC_AUTH
 
 extern bool global_machine_password_needs_changing;
+static struct named_mutex *mutex;
 
 /**
  * Connect to a remote server for (inter)domain security authenticaion.
@@ -67,7 +68,8 @@ static NTSTATUS connect_to_domain_password_server(struct cli_state **cli,
 	 * ACCESS_DENIED errors if 2 auths are done from the same machine. JRA.
 	 */
 
-	if (!grab_server_mutex(dc_name)) {
+	mutex = grab_named_mutex(NULL, dc_name, 10);
+	if (mutex == NULL) {
 		return NT_STATUS_NO_LOGON_SERVERS;
 	}
 	
@@ -87,7 +89,7 @@ static NTSTATUS connect_to_domain_password_server(struct cli_state **cli,
 			*cli = NULL;
 		}
 
-		release_server_mutex();
+		TALLOC_FREE(mutex);
 		return result;
 	}
 
@@ -118,7 +120,7 @@ static NTSTATUS connect_to_domain_password_server(struct cli_state **cli,
 machine %s. Error was : %s.\n", dc_name, nt_errstr(result)));
 		cli_shutdown(*cli);
 		*cli = NULL;
-		release_server_mutex();
+		TALLOC_FREE(mutex);
 		return result;
 	}
 
@@ -137,7 +139,7 @@ machine %s. Error was : %s.\n", dc_name, nt_errstr(result)));
 				domain));
 			cli_shutdown(*cli);
 			*cli = NULL;
-			release_server_mutex();
+			TALLOC_FREE(mutex);
 			return NT_STATUS_CANT_ACCESS_DOMAIN_INFO;
 		}
 
@@ -153,7 +155,7 @@ machine %s. Error was : %s.\n", dc_name, nt_errstr(result)));
 		if (!NT_STATUS_IS_OK(result)) {
 			cli_shutdown(*cli);
 			*cli = NULL;
-			release_server_mutex();
+			TALLOC_FREE(mutex);
 			return result;
 		}
 	}
@@ -163,7 +165,7 @@ machine %s. Error was : %s.\n", dc_name, nt_errstr(result)));
 machine %s. Error was : %s.\n", dc_name, cli_errstr(*cli)));
 		cli_shutdown(*cli);
 		*cli = NULL;
-		release_server_mutex();
+		TALLOC_FREE(mutex);
 		return NT_STATUS_NO_LOGON_SERVERS;
 	}
 
@@ -247,7 +249,7 @@ static NTSTATUS domain_client_validate(TALLOC_CTX *mem_ctx,
 	/* Let go as soon as possible so we avoid any potential deadlocks
 	   with winbind lookup up users or groups. */
 	   
-	release_server_mutex();
+	TALLOC_FREE(mutex);
 
 	if (!NT_STATUS_IS_OK(nt_status)) {
 		DEBUG(0,("domain_client_validate: unable to validate password "
diff --git a/source3/auth/auth_server.c b/source3/auth/auth_server.c
index 095f0b9fb8..b07884c49b 100644
--- a/source3/auth/auth_server.c
+++ b/source3/auth/auth_server.c
@@ -37,6 +37,7 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 	const char *p;
 	char *pserver = NULL;
 	bool connected_ok = False;
+	struct named_mutex *mutex;
 
 	if (!(cli = cli_initialise()))
 		return NULL;
@@ -74,7 +75,8 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 		   session setup yet it will send a TCP reset to the first
 		   connection (tridge) */
 
-		if (!grab_server_mutex(desthost)) {
+		mutex = grab_named_mutex(talloc_tos(), desthost, 10);
+		if (mutex == NULL) {
 			cli_shutdown(cli);
 			return NULL;
 		}
@@ -87,7 +89,7 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 		}
 		DEBUG(10,("server_cryptkey: failed to connect to server %s. Error %s\n",
 			desthost, nt_errstr(status) ));
-		release_server_mutex();
+		TALLOC_FREE(mutex);
 	}
 
 	if (!connected_ok) {
@@ -98,7 +100,7 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 
 	if (!attempt_netbios_session_request(&cli, global_myname(),
 					     desthost, &dest_ss)) {
-		release_server_mutex();
+		TALLOC_FREE(mutex);
 		DEBUG(1,("password server fails session request\n"));
 		cli_shutdown(cli);
 		return NULL;
@@ -111,16 +113,16 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 	DEBUG(3,("got session\n"));
 
 	if (!cli_negprot(cli)) {
+		TALLOC_FREE(mutex);
 		DEBUG(1,("%s rejected the negprot\n",desthost));
-		release_server_mutex();
 		cli_shutdown(cli);
 		return NULL;
 	}
 
 	if (cli->protocol < PROTOCOL_LANMAN2 ||
 	    !(cli->sec_mode & NEGOTIATE_SECURITY_USER_LEVEL)) {
+		TALLOC_FREE(mutex);
 		DEBUG(1,("%s isn't in user level security mode\n",desthost));
-		release_server_mutex();
 		cli_shutdown(cli);
 		return NULL;
 	}
@@ -132,14 +134,14 @@ static struct cli_state *server_cryptkey(TALLOC_CTX *mem_ctx)
 
 	if (!NT_STATUS_IS_OK(cli_session_setup(cli, "", "", 0, "", 0,
 					       ""))) {
+		TALLOC_FREE(mutex);
 		DEBUG(0,("%s rejected the initial session setup (%s)\n",
 			 desthost, cli_errstr(cli)));
-		release_server_mutex();
 		cli_shutdown(cli);
 		return NULL;
 	}
 
-	release_server_mutex();
+	TALLOC_FREE(mutex);
 
 	DEBUG(3,("password server OK\n"));
 
diff --git a/source3/include/smb.h b/source3/include/smb.h
index c582a97e5c..bf9ca6b92c 100644
--- a/source3/include/smb.h
+++ b/source3/include/smb.h
@@ -420,6 +420,7 @@ struct timed_event;
 struct idle_event;
 struct share_mode_entry;
 struct uuid;
+struct named_mutex;
 
 struct vfs_fsp_data {
     struct vfs_fsp_data *next;
diff --git a/source3/lib/server_mutex.c b/source3/lib/server_mutex.c
index 2700aa103b..43c0de1975 100644
--- a/source3/lib/server_mutex.c
+++ b/source3/lib/server_mutex.c
@@ -28,28 +28,51 @@
    This locking allows smbd's mutlithread architecture to look
    like the single-connection that NT makes. */
 
-static char *mutex_server_name;
+struct named_mutex {
+	struct tdb_wrap *tdb;
+	char *name;
+};
 
-bool grab_server_mutex(const char *name)
+static int unlock_named_mutex(struct named_mutex *mutex)
 {
-	mutex_server_name = SMB_STRDUP(name);
-	if (!mutex_server_name) {
-		DEBUG(0,("grab_server_mutex: malloc failed for %s\n", name));
-		return False;
+	tdb_unlock_bystring(mutex->tdb->tdb, mutex->name);
+	return 0;
+}
+
+struct named_mutex *grab_named_mutex(TALLOC_CTX *mem_ctx, const char *name,
+				     int timeout)
+{
+	struct named_mutex *result;
+
+	result = talloc(mem_ctx, struct named_mutex);
+	if (result == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		return NULL;
 	}
-	if (!secrets_named_mutex(mutex_server_name, 10)) {
-		DEBUG(10,("grab_server_mutex: failed for %s\n", name));
-		SAFE_FREE(mutex_server_name);
-		return False;
+
+	result->name = talloc_strdup(result, name);
+	if (result->name == NULL) {
+		DEBUG(0, ("talloc failed\n"));
+		TALLOC_FREE(result);
+		return NULL;
 	}
 
-	return True;
-}
+	result->tdb = tdb_wrap_open(result, lock_path("mutex.tdb"), 0,
+				    TDB_DEFAULT, O_RDWR|O_CREAT, 0600);
+	if (result->tdb == NULL) {
+		DEBUG(1, ("Could not open mutex.tdb: %s\n",
+			  strerror(errno)));
+		TALLOC_FREE(result);
+		return NULL;
+	}
 
-void release_server_mutex(void)
-{
-	if (mutex_server_name) {
-		secrets_named_mutex_release(mutex_server_name);
-		SAFE_FREE(mutex_server_name);
+	if (tdb_lock_bystring_with_timeout(result->tdb->tdb, name,
+					   timeout) == -1) {
+		DEBUG(1, ("Could not get the lock for %s\n", name));
+		TALLOC_FREE(result);
+		return NULL;
 	}
+
+	talloc_set_destructor(result, unlock_named_mutex);
+	return result;
 }
diff --git a/source3/libads/kerberos_verify.c b/source3/libads/kerberos_verify.c
index f112dd34e3..6b482ecd20 100644
--- a/source3/libads/kerberos_verify.c
+++ b/source3/libads/kerberos_verify.c
@@ -330,8 +330,8 @@ NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
 	krb5_const_principal client_principal = NULL;
 	char *host_princ_s = NULL;
 	bool auth_ok = False;
-	bool got_replay_mutex = False;
 	bool got_auth_data = False;
+	struct named_mutex *mutex = NULL;
 
 	ZERO_STRUCT(packet);
 	ZERO_STRUCT(auth_data);
@@ -395,15 +395,15 @@ NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
 		   locking in the MIT krb5 code surrounding the replay 
 		   cache... */
 
-		if (!grab_server_mutex("replay cache mutex")) {
+		mutex = grab_named_mutex(talloc_tos(), "replay cache mutex",
+					 10);
+		if (mutex == NULL) {
 			DEBUG(1,("ads_verify_ticket: unable to protect "
 				 "replay cache with mutex.\n"));
 			ret = KRB5_CC_IO;
 			goto out;
 		}
 
-		got_replay_mutex = True;
-
 		/* JRA. We must set the rcache here. This will prevent 
 		   replay attacks. */
 		
@@ -443,8 +443,7 @@ NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
 	}
 
 	if ( use_replay_cache ) {		
-		release_server_mutex();
-		got_replay_mutex = False;
+		TALLOC_FREE(mutex);
 #if 0
 		/* Heimdal leaks here, if we fix the leak, MIT crashes */
 		if (rcache) {
@@ -539,9 +538,7 @@ NTSTATUS ads_verify_ticket(TALLOC_CTX *mem_ctx,
 
  out:
 
-	if (got_replay_mutex) {
-		release_server_mutex();
-	}
+	TALLOC_FREE(mutex);
 
 	if (!NT_STATUS_IS_OK(sret)) {
 		data_blob_free(&auth_data);
diff --git a/source3/passdb/secrets.c b/source3/passdb/secrets.c
index 2c0d648716..8448f795b4 100644
--- a/source3/passdb/secrets.c
+++ b/source3/passdb/secrets.c
@@ -1029,37 +1029,6 @@ NTSTATUS secrets_trusted_domains(TALLOC_CTX *mem_ctx, uint32 *num_domains,
 }
 
 /*******************************************************************************
- Lock the secrets tdb based on a string - this is used as a primitive form of mutex
- between smbd instances.
-*******************************************************************************/
-
-bool secrets_named_mutex(const char *name, unsigned int timeout)
-{
-	int ret = 0;
-
-	if (!secrets_init()) {
-		return false;
-	}
-
-	ret = tdb_lock_bystring_with_timeout(tdb, name, timeout);
-	if (ret == 0) {
-		DEBUG(10,("secrets_named_mutex: got mutex for %s\n", name ));
-	}
-
-	return (ret == 0);
-}
-
-/*******************************************************************************
- Unlock a named mutex.
-*******************************************************************************/
-
-void secrets_named_mutex_release(const char *name)
-{
-	tdb_unlock_bystring(tdb, name);
-	DEBUG(10,("secrets_named_mutex: released mutex for %s\n", name ));
-}
-
-/*******************************************************************************
  Store a complete AFS keyfile into secrets.tdb.
 *******************************************************************************/
 
diff --git a/source3/winbindd/winbindd_cm.c b/source3/winbindd/winbindd_cm.c
index 0f536cdfb8..072b4ee98f 100644
--- a/source3/winbindd/winbindd_cm.c
+++ b/source3/winbindd/winbindd_cm.c
@@ -747,7 +747,7 @@ static NTSTATUS cm_prepare_connection(const struct winbindd_domain *domain,
 	char *ipc_domain = NULL;
 	char *ipc_password = NULL;
 
-	bool got_mutex;
+	struct named_mutex *mutex;
 
 	NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
 
@@ -761,10 +761,9 @@ static NTSTATUS cm_prepare_connection(const struct winbindd_domain *domain,
 
 	*retry = True;
 
-	got_mutex = secrets_named_mutex(controller,
-					WINBIND_SERVER_MUTEX_WAIT_TIME);
-
-	if (!got_mutex) {
+	mutex = grab_named_mutex(talloc_tos(), controller,
+				 WINBIND_SERVER_MUTEX_WAIT_TIME);
+	if (mutex == NULL) {
 		DEBUG(0,("cm_prepare_connection: mutex grab failed for %s\n",
 			 controller));
 		result = NT_STATUS_POSSIBLE_DEADLOCK;
@@ -952,8 +951,7 @@ static NTSTATUS cm_prepare_connection(const struct winbindd_domain *domain,
 		goto done;
 	}
 
-	secrets_named_mutex_release(controller);
-	got_mutex = False;
+	TALLOC_FREE(mutex);
 	*retry = False;
 
 	/* set the domain if empty; needed for schannel connections */
@@ -964,10 +962,7 @@ static NTSTATUS cm_prepare_connection(const struct winbindd_domain *domain,
 	result = NT_STATUS_OK;
 
  done:
-	if (got_mutex) {
-		secrets_named_mutex_release(controller);
-	}
-
+	TALLOC_FREE(mutex);
 	SAFE_FREE(machine_account);
 	SAFE_FREE(machine_password);
 	SAFE_FREE(machine_krb5_principal);