RDMA/cma: Allow user to restrict listens to bound address family

Provide an option for the user to specify that listens should only
accept connections where the incoming address family matches that of
the locally bound address.  This is used to support the equivalent of
IPV6_V6ONLY socket option, which allows an app to only accept
connection requests directed to IPv6 addresses.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/core/cma.c

@@ -99,6 +99,10 @@ struct rdma_bind_list {
 	unsigned short		port;
 };
 
+enum {
+	CMA_OPTION_AFONLY,
+};
+
 /*
  * Device removal can occur at anytime, so we need extra handling to
  * serialize notifying the user of device removal with other callbacks.
@@ -137,6 +141,7 @@ struct rdma_id_private {
 	u32			qkey;
 	u32			qp_num;
 	pid_t			owner;
+	u32			options;
 	u8			srq;
 	u8			tos;
 	u8			reuseaddr;
@@ -2104,6 +2109,26 @@ int rdma_set_reuseaddr(struct rdma_cm_id *id, int reuse)
 }
 EXPORT_SYMBOL(rdma_set_reuseaddr);
 
+int rdma_set_afonly(struct rdma_cm_id *id, int afonly)
+{
+	struct rdma_id_private *id_priv;
+	unsigned long flags;
+	int ret;
+
+	id_priv = container_of(id, struct rdma_id_private, id);
+	spin_lock_irqsave(&id_priv->lock, flags);
+	if (id_priv->state == RDMA_CM_IDLE || id_priv->state == RDMA_CM_ADDR_BOUND) {
+		id_priv->options |= (1 << CMA_OPTION_AFONLY);
+		id_priv->afonly = afonly;
+		ret = 0;
+	} else {
+		ret = -EINVAL;
+	}
+	spin_unlock_irqrestore(&id_priv->lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(rdma_set_afonly);
+
 static void cma_bind_port(struct rdma_bind_list *bind_list,
 			  struct rdma_id_private *id_priv)
 {
@@ -2379,12 +2404,14 @@ int rdma_bind_addr(struct rdma_cm_id *id, struct sockaddr *addr)
 	}
 
 	memcpy(&id->route.addr.src_addr, addr, ip_addr_size(addr));
-	if (addr->sa_family == AF_INET)
-		id_priv->afonly = 1;
+	if (!(id_priv->options & (1 << CMA_OPTION_AFONLY))) {
+		if (addr->sa_family == AF_INET)
+			id_priv->afonly = 1;
 #if IS_ENABLED(CONFIG_IPV6)
-	else if (addr->sa_family == AF_INET6)
-		id_priv->afonly = init_net.ipv6.sysctl.bindv6only;
+		else if (addr->sa_family == AF_INET6)
+			id_priv->afonly = init_net.ipv6.sysctl.bindv6only;
 #endif
+	}
 	ret = cma_get_port(id_priv);
 	if (ret)
 		goto err2;

drivers/infiniband/core/ucma.c

@@ -909,6 +909,13 @@ static int ucma_set_option_id(struct ucma_context *ctx, int optname,
 		}
 		ret = rdma_set_reuseaddr(ctx->cm_id, *((int *) optval) ? 1 : 0);
 		break;
+	case RDMA_OPTION_ID_AFONLY:
+		if (optlen != sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		ret = rdma_set_afonly(ctx->cm_id, *((int *) optval) ? 1 : 0);
+		break;
 	default:
 		ret = -ENOSYS;
 	}

include/rdma/rdma_cm.h

@@ -357,4 +357,14 @@ void rdma_set_service_type(struct rdma_cm_id *id, int tos);
  */
 int rdma_set_reuseaddr(struct rdma_cm_id *id, int reuse);
 
+/**
+ * rdma_set_afonly - Specify that listens are restricted to the
+ *    bound address family only.
+ * @id: Communication identifer to configure.
+ * @afonly: Value indicating if listens are restricted.
+ *
+ * Must be set before identifier is in the listening state.
+ */
+int rdma_set_afonly(struct rdma_cm_id *id, int afonly);
+
 #endif /* RDMA_CM_H */

include/rdma/rdma_user_cm.h

@@ -224,6 +224,7 @@ enum {
 enum {
 	RDMA_OPTION_ID_TOS	 = 0,
 	RDMA_OPTION_ID_REUSEADDR = 1,
+	RDMA_OPTION_ID_AFONLY	 = 2,
 	RDMA_OPTION_IB_PATH	 = 1
 };