netinet6: Tear down IPv6 source address selection policies with rest of IPv6.

This may plug minor leaks which no-one has reported. The default IPv6 source
address selection policy list in FreeBSD is usually limited to 9 entries,
and can be readily inspected with ip6addrctl(8). The policy table is
however instantiated for each VNET.

The leak of a pol instance in delete_addrsel_policyent() was already
plugged by @ae in commit-id ecc5c73, so that change has not been merged.

Do not tear down the sxlocks as glebius has requested, and move the
addrsel_policyent{} declarations further up to avoid redundant forward
declarations as glebius requested for stylistic reasons.

Reviewed by:	ae, pouria
Sponsored by:	Cisco Systems, Inc.
Differential Revision: https://reviews.freebsd.org/D55599

sys/netinet6/in6.h

@@ -690,6 +690,7 @@ void	in6_sin_2_v4mapsin6(const struct sockaddr_in *sin,
 	    struct sockaddr_in6 *sin6);
 void	in6_sin6_2_sin_in_sock(struct sockaddr *nam);
 extern void addrsel_policy_init(void);
+void	addrsel_policy_destroy(void);
 
 #define	satosin6(sa)	((struct sockaddr_in6 *)(sa))
 #define	sin6tosa(sin6)	((struct sockaddr *)(sin6))

sys/netinet6/in6_src.c

@@ -886,6 +886,22 @@ in6_selecthlim(struct inpcb *inp, struct ifnet *ifp)
 	return (V_ip6_defhlim);
 }
 
+/*
+ * The followings are implementation of the policy table using a
+ * simple tail queue.
+ * XXX such details should be hidden.
+ * XXX implementation using binary tree should be more efficient.
+ */
+struct addrsel_policyent {
+	TAILQ_ENTRY(addrsel_policyent) ape_entry;
+	struct in6_addrpolicy ape_policy;
+};
+
+TAILQ_HEAD(addrsel_policyhead, addrsel_policyent);
+
+VNET_DEFINE_STATIC(struct addrsel_policyhead, addrsel_policytab);
+#define	V_addrsel_policytab		VNET(addrsel_policytab)
+
 void
 addrsel_policy_init(void)
 {
@@ -903,6 +919,18 @@ addrsel_policy_init(void)
 	ADDRSEL_SXLOCK_INIT();
 }
 
+void
+addrsel_policy_destroy(void)
+{
+	struct addrsel_policyent *pol, *tpol;
+
+	TAILQ_FOREACH_SAFE(pol, &V_addrsel_policytab, ape_entry, tpol) {
+		TAILQ_REMOVE(&V_addrsel_policytab, pol, ape_entry);
+		free(pol, M_IFADDR);
+	}
+	/* TODO: Perform matching destruction of locks elsewhere. */
+}
+
 static struct in6_addrpolicy *
 lookup_addrsel_policy(struct sockaddr_in6 *key)
 {
@@ -976,22 +1004,6 @@ in6_src_ioctl(u_long cmd, caddr_t data)
 	return (0);		/* XXX: compromise compilers */
 }
 
-/*
- * The followings are implementation of the policy table using a
- * simple tail queue.
- * XXX such details should be hidden.
- * XXX implementation using binary tree should be more efficient.
- */
-struct addrsel_policyent {
-	TAILQ_ENTRY(addrsel_policyent) ape_entry;
-	struct in6_addrpolicy ape_policy;
-};
-
-TAILQ_HEAD(addrsel_policyhead, addrsel_policyent);
-
-VNET_DEFINE_STATIC(struct addrsel_policyhead, addrsel_policytab);
-#define	V_addrsel_policytab		VNET(addrsel_policytab)
-
 static void
 init_policy_queue(void)
 {

sys/netinet6/ip6_input.c

@@ -398,6 +398,7 @@ ip6_destroy(void *unused __unused)
 
 	frag6_destroy();
 	nd6_destroy();
+	addrsel_policy_destroy();
 	in6_ifattach_destroy();
 
 	hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);