From: Stefan Metzmacher <metze@samba.org>
Date: Fri, 7 Feb 2025 12:43:10 +0000 (+0100)
Subject: winbindd: add struct winbindd_domain_ref infrastructure
X-Git-Tag: tevent-0.17.0~842
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5d9db5cccc086bfcefa33daa7c03443d0614e982;p=thirdparty%2Fsamba.git

winbindd: add struct winbindd_domain_ref infrastructure

In the next commits it will be possible that
struct winbindd_domain instances become stale
because trusted domains were reloaded.

That means aync state structure should not use
pointers to 'struct winbindd_domain' as they
can become stale!

Instead they should use 'struct winbindd_domain_ref domain'
in the async state and use winbindd_domain_ref_set/get()
to manage the 'struct winbindd_domain' pointer.

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
---

diff --git a/source3/winbindd/winbindd.h b/source3/winbindd/winbindd.h
index dd1163663b0..144fd466e6e 100644
--- a/source3/winbindd/winbindd.h
+++ b/source3/winbindd/winbindd.h
@@ -67,6 +67,35 @@ struct winbindd_cli_state {
 	struct getgrent_state *grent_state; /* State for getgrent() */
 };
 
+struct winbindd_domain;
+
+struct winbindd_domain_ref_internals {
+	const char *location;
+	const char *func;
+	bool stale;
+	struct dom_sid sid;
+	uint64_t generation;
+	struct winbindd_domain *domain; /* might be stale */
+};
+
+struct winbindd_domain_ref {
+	struct winbindd_domain_ref_internals internals;
+};
+
+void _winbindd_domain_ref_set(struct winbindd_domain_ref *ref,
+			      struct winbindd_domain *domain,
+			      const char *location,
+			      const char *func);
+#define winbindd_domain_ref_set(__ref, __domain) \
+	_winbindd_domain_ref_set(__ref, __domain, __location__, __func__)
+
+bool _winbindd_domain_ref_get(struct winbindd_domain_ref *ref,
+			      struct winbindd_domain **_domain,
+			      const char *location,
+			      const char *func);
+#define winbindd_domain_ref_get(__ref, __domain) \
+	_winbindd_domain_ref_get(__ref, __domain, __location__, __func__)
+
 struct getpwent_state {
 	struct winbindd_domain *domain;
 	uint32_t next_user;
@@ -101,8 +130,6 @@ struct winbindd_cm_conn {
 
 /* Async child */
 
-struct winbindd_domain;
-
 struct winbindd_child {
 	pid_t pid;
 	struct winbindd_domain *domain; /* if valid also talloc (grant) parent */
diff --git a/source3/winbindd/winbindd_util.c b/source3/winbindd/winbindd_util.c
index 23b34b01641..e66e0754604 100644
--- a/source3/winbindd/winbindd_util.c
+++ b/source3/winbindd/winbindd_util.c
@@ -53,6 +53,7 @@
    the domain name instead. */
 
 static struct winbindd_domain *_domain_list = NULL;
+static uint64_t domain_list_generation;
 
 struct winbindd_domain *domain_list(void)
 {
@@ -87,6 +88,79 @@ struct winbindd_domain *wb_next_domain(struct winbindd_domain *domain)
 	return domain;
 }
 
+void _winbindd_domain_ref_set(struct winbindd_domain_ref *ref,
+			      struct winbindd_domain *domain,
+			      const char *location,
+			      const char *func)
+{
+	if (domain == NULL) {
+		ref->internals = (struct winbindd_domain_ref_internals) {
+			.location = location,
+			.func = func,
+		};
+		return;
+	}
+
+	ref->internals = (struct winbindd_domain_ref_internals) {
+		.location = location,
+		.func = func,
+		.sid = domain->sid,
+		.generation = domain_list_generation,
+		.domain = domain,
+	};
+}
+
+bool _winbindd_domain_ref_get(struct winbindd_domain_ref *ref,
+			      struct winbindd_domain **_domain,
+			      const char *location,
+			      const char *func)
+{
+	struct winbindd_domain *domain = NULL;
+
+	if (ref->internals.stale) {
+		goto stale;
+	}
+
+	if (ref->internals.domain == NULL) {
+		*_domain = NULL;
+		return true;
+	}
+
+	if (ref->internals.generation == domain_list_generation) {
+		*_domain = ref->internals.domain;
+		return true;
+	}
+
+	domain = find_domain_from_sid_noinit(&ref->internals.sid);
+stale:
+	if (domain == NULL) {
+		struct dom_sid_buf sbuf = {};
+
+		D_ERR("%s:%s: stale domain %s, set in %s\n",
+		      func,
+		      location,
+		      dom_sid_str_buf(&ref->internals.sid, &sbuf),
+		      ref->internals.location);
+
+		ref->internals.stale = true;
+		ref->internals.domain = NULL;
+
+		*_domain = NULL;
+		return false;
+	}
+
+	ref->internals = (struct winbindd_domain_ref_internals) {
+		.location = location,
+		.func = func,
+		.sid = domain->sid,
+		.generation = domain_list_generation,
+		.domain = domain,
+	};
+
+	*_domain = domain;
+	return true;
+}
+
 static bool is_internal_domain(const struct dom_sid *sid)
 {
 	if (sid == NULL)
@@ -292,6 +366,7 @@ static NTSTATUS add_trusted_domain(const char *domain_name,
 
 	/* Link to domain list */
 	DLIST_ADD_END(_domain_list, domain);
+	domain_list_generation += 1;
 
 	wcache_tdc_add_domain( domain );