tipc: add UDP remoteip dump to netlink API

When using replicast a UDP bearer can have an arbitrary amount of
remote ip addresses associated with it. This means we cannot simply
add all remote ip addresses to an existing bearer data message as it
might fill the message, leaving us with a truncated message that we
can't safely resume. To handle this we introduce the new netlink
command TIPC_NL_UDP_GET_REMOTEIP. This command is intended to be
called when the bearer data message has the
TIPC_NLA_UDP_MULTI_REMOTEIP flag set, indicating there are more than
one remote ip (replicast).

Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/netlink.c

@@ -41,6 +41,7 @@
 #include "link.h"
 #include "node.h"
 #include "net.h"
+#include "udp_media.h"
 #include <net/genetlink.h>
 
 static const struct nla_policy tipc_nl_policy[TIPC_NLA_MAX + 1] = {
@@ -247,7 +248,14 @@ static const struct genl_ops tipc_genl_v2_ops[] = {
 		.cmd	= TIPC_NL_PEER_REMOVE,
 		.doit	= tipc_nl_peer_rm,
 		.policy = tipc_nl_policy,
-	}
+	},
+#ifdef CONFIG_TIPC_MEDIA_UDP
+	{
+		.cmd	= TIPC_NL_UDP_GET_REMOTEIP,
+		.dumpit	= tipc_udp_nl_dump_remoteip,
+		.policy = tipc_nl_policy,
+	},
+#endif
 };
 
 int tipc_nlmsg_parse(const struct nlmsghdr *nlh, struct nlattr ***attr)

net/tipc/udp_media.c

@@ -428,6 +428,96 @@ static int __tipc_nl_add_udp_addr(struct sk_buff *skb,
 	return 0;
 }
 
+int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	u32 bid = cb->args[0];
+	u32 skip_cnt = cb->args[1];
+	u32 portid = NETLINK_CB(cb->skb).portid;
+	struct udp_replicast *rcast, *tmp;
+	struct tipc_bearer *b;
+	struct udp_bearer *ub;
+	void *hdr;
+	int err;
+	int i;
+
+	if (!bid && !skip_cnt) {
+		struct net *net = sock_net(skb->sk);
+		struct nlattr *battrs[TIPC_NLA_BEARER_MAX + 1];
+		struct nlattr **attrs;
+		char *bname;
+
+		err = tipc_nlmsg_parse(cb->nlh, &attrs);
+		if (err)
+			return err;
+
+		if (!attrs[TIPC_NLA_BEARER])
+			return -EINVAL;
+
+		err = nla_parse_nested(battrs, TIPC_NLA_BEARER_MAX,
+				       attrs[TIPC_NLA_BEARER],
+				       tipc_nl_bearer_policy);
+		if (err)
+			return err;
+
+		if (!battrs[TIPC_NLA_BEARER_NAME])
+			return -EINVAL;
+
+		bname = nla_data(battrs[TIPC_NLA_BEARER_NAME]);
+
+		rtnl_lock();
+		b = tipc_bearer_find(net, bname);
+		if (!b) {
+			rtnl_unlock();
+			return -EINVAL;
+		}
+		bid = b->identity;
+	} else {
+		struct net *net = sock_net(skb->sk);
+		struct tipc_net *tn = net_generic(net, tipc_net_id);
+
+		rtnl_lock();
+		b = rtnl_dereference(tn->bearer_list[bid]);
+		if (!b) {
+			rtnl_unlock();
+			return -EINVAL;
+		}
+	}
+
+	ub = rcu_dereference_rtnl(b->media_ptr);
+	if (!ub) {
+		rtnl_unlock();
+		return -EINVAL;
+	}
+
+	i = 0;
+	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
+		if (i < skip_cnt)
+			goto count;
+
+		hdr = genlmsg_put(skb, portid, cb->nlh->nlmsg_seq,
+				  &tipc_genl_family, NLM_F_MULTI,
+				  TIPC_NL_BEARER_GET);
+		if (!hdr)
+			goto done;
+
+		err = __tipc_nl_add_udp_addr(skb, &rcast->addr,
+					     TIPC_NLA_UDP_REMOTE);
+		if (err) {
+			genlmsg_cancel(skb, hdr);
+			goto done;
+		}
+		genlmsg_end(skb, hdr);
+count:
+		i++;
+	}
+done:
+	rtnl_unlock();
+	cb->args[0] = bid;
+	cb->args[1] = i;
+
+	return skb->len;
+}
+
 int tipc_udp_nl_add_bearer_data(struct tipc_nl_msg *msg, struct tipc_bearer *b)
 {
 	struct udp_media_addr *src = (struct udp_media_addr *)&b->addr.value;

net/tipc/udp_media.h

@@ -40,6 +40,7 @@
 
 int tipc_udp_nl_bearer_add(struct tipc_bearer *b, struct nlattr *attr);
 int tipc_udp_nl_add_bearer_data(struct tipc_nl_msg *msg, struct tipc_bearer *b);
+int tipc_udp_nl_dump_remoteip(struct sk_buff *skb, struct netlink_callback *cb);
 
 #endif
 #endif