s4-dsdb: create a static system_session context

This patch adds a system_session cache, preventing us from having to
recreate it on every ldb open, and allowing us to detect when the same
session is being used in ldb_wrap

6 files changed, 27 insertions, 12 deletions

diff --git a/source4/auth/auth.h b/source4/auth/auth.h
index 8a0f12efd8..49cf161241 100644
--- a/source4/auth/auth.h
+++ b/source4/auth/auth.h
@@ -236,7 +236,7 @@ NTSTATUS authsam_account_ok(TALLOC_CTX *mem_ctx,
 			    const char *name_for_logs,
 			    bool allow_domain_trust,
 			    bool password_change);
-struct auth_session_info *system_session(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx);
+struct auth_session_info *system_session(struct loadparm_context *lp_ctx);
 NTSTATUS authsam_make_server_info(TALLOC_CTX *mem_ctx, struct ldb_context *sam_ctx,
 					   const char *netbios_name,
 					   const char *domain_name,
diff --git a/source4/auth/gensec/schannel_state.c b/source4/auth/gensec/schannel_state.c
index 7aa0ba3d69..163ae1570d 100644
--- a/source4/auth/gensec/schannel_state.c
+++ b/source4/auth/gensec/schannel_state.c
@@ -48,8 +48,8 @@ struct ldb_context *schannel_db_connect(TALLOC_CTX *mem_ctx, struct tevent_conte
 	existed = file_exist(path);
 	
 	ldb = ldb_wrap_connect(mem_ctx, ev_ctx, lp_ctx, path, 
-			       system_session(mem_ctx, lp_ctx), 
-			       NULL, LDB_FLG_NOSYNC, NULL);
+			       system_session(lp_ctx), 
+			       NULL, LDB_FLG_NOSYNC);
 	talloc_free(path);
 	if (!ldb) {
 		return NULL;
diff --git a/source4/auth/ntlm/auth_sam.c b/source4/auth/ntlm/auth_sam.c
index 46cdd8d24e..baa95f7380 100644
--- a/source4/auth/ntlm/auth_sam.c
+++ b/source4/auth/ntlm/auth_sam.c
@@ -202,7 +202,7 @@ static NTSTATUS authsam_check_password_internals(struct auth_method_context *ctx
 		return NT_STATUS_NO_MEMORY;
 	}
 
-	sam_ctx = samdb_connect(tmp_ctx, ctx->auth_ctx->event_ctx, ctx->auth_ctx->lp_ctx, system_session(mem_ctx, ctx->auth_ctx->lp_ctx));
+	sam_ctx = samdb_connect(tmp_ctx, ctx->auth_ctx->event_ctx, ctx->auth_ctx->lp_ctx, system_session(ctx->auth_ctx->lp_ctx));
 	if (sam_ctx == NULL) {
 		talloc_free(tmp_ctx);
 		return NT_STATUS_INVALID_SYSTEM_SERVICE;
@@ -320,7 +320,7 @@ NTSTATUS authsam_get_server_info_principal(TALLOC_CTX *mem_ctx,
 	}
 
 	sam_ctx = samdb_connect(tmp_ctx, auth_context->event_ctx, auth_context->lp_ctx, 
-				system_session(tmp_ctx, auth_context->lp_ctx));
+				system_session(auth_context->lp_ctx));
 	if (sam_ctx == NULL) {
 		talloc_free(tmp_ctx);
 		return NT_STATUS_INVALID_SYSTEM_SERVICE;
diff --git a/source4/auth/pyauth.c b/source4/auth/pyauth.c
index 5bb775aa95..7ec7f3e7f2 100644
--- a/source4/auth/pyauth.c
+++ b/source4/auth/pyauth.c
@@ -49,7 +49,7 @@ static PyObject *py_system_session(PyObject *module, PyObject *args)
 	if (lp_ctx == NULL)
 		return NULL;
 
-	session = system_session(NULL, lp_ctx);
+	session = system_session(lp_ctx);
 
 	return PyAuthSession_FromSession(session);
 }
diff --git a/source4/auth/session.h b/source4/auth/session.h
index ca47af33f4..2a5a8f1098 100644
--- a/source4/auth/session.h
+++ b/source4/auth/session.h
@@ -35,7 +35,7 @@ struct tevent_context;
 /* Create a security token for a session SYSTEM (the most
  * trusted/prvilaged account), including the local machine account as
  * the off-host credentials */
-struct auth_session_info *system_session(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx) ;
+struct auth_session_info *system_session(struct loadparm_context *lp_ctx) ;
 
 /*
  * Create a system session, but with anonymous credentials (so we do
diff --git a/source4/auth/system_session.c b/source4/auth/system_session.c
index 8e22bd820e..765f53a613 100644
--- a/source4/auth/system_session.c
+++ b/source4/auth/system_session.c
@@ -146,22 +146,37 @@ static NTSTATUS generate_session_info(TALLOC_CTX *mem_ctx,
 }
 
 
+/*
+  prevent the static system session being freed
+ */
+static int system_session_destructor(struct auth_session_info *info)
+{
+	return -1;
+}
 
 /* Create a security token for a session SYSTEM (the most
  * trusted/prvilaged account), including the local machine account as
  * the off-host credentials
  */ 
-_PUBLIC_ struct auth_session_info *system_session(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx) 
+_PUBLIC_ struct auth_session_info *system_session(struct loadparm_context *lp_ctx) 
 {
+	static struct auth_session_info *static_session;
 	NTSTATUS nt_status;
-	struct auth_session_info *session_info = NULL;
-	nt_status = auth_system_session_info(mem_ctx,
+
+	if (static_session) {
+		return static_session;
+	}
+
+	nt_status = auth_system_session_info(talloc_autofree_context(),
 					     lp_ctx,
-					     &session_info);
+					     &static_session);
 	if (!NT_STATUS_IS_OK(nt_status)) {
+		talloc_free(static_session);
+		static_session = NULL;
 		return NULL;
 	}
-	return session_info;
+	talloc_set_destructor(static_session, system_session_destructor);
+	return static_session;
 }
 
 static NTSTATUS _auth_system_session_info(TALLOC_CTX *parent_ctx,