net: Plumb support for filtering ipv4 and ipv6 multicast route dumps

Implement kernel side filtering of routes by egress device index and
table id. If the table id is given in the filter, lookup table and
call mr_table_dump directly for it.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 55 insertions, 6 deletions

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 44d777058960..3fa988e6a3df 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -2528,18 +2528,30 @@ errout_free:
 static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct fib_dump_filter filter = {};
+	int err;
 
 	if (cb->strict_check) {
-		int err;
-
 		err = ip_valid_fib_dump_req(sock_net(skb->sk), cb->nlh,
 					    &filter, cb->extack);
 		if (err < 0)
 			return err;
 	}
 
+	if (filter.table_id) {
+		struct mr_table *mrt;
+
+		mrt = ipmr_get_table(sock_net(skb->sk), filter.table_id);
+		if (!mrt) {
+			NL_SET_ERR_MSG(cb->extack, "ipv4: MR table does not exist");
+			return -ENOENT;
+		}
+		err = mr_table_dump(mrt, skb, cb, _ipmr_fill_mroute,
+				    &mfc_unres_lock, &filter);
+		return skb->len ? : err;
+	}
+
 	return mr_rtm_dumproute(skb, cb, ipmr_mr_table_iter,
-				_ipmr_fill_mroute, &mfc_unres_lock);
+				_ipmr_fill_mroute, &mfc_unres_lock, &filter);
 }
 
 static const struct nla_policy rtm_ipmr_policy[RTA_MAX + 1] = {
diff --git a/net/ipv4/ipmr_base.c b/net/ipv4/ipmr_base.c
index 132dd2613ca5..844806120f44 100644
--- a/net/ipv4/ipmr_base.c
+++ b/net/ipv4/ipmr_base.c
@@ -268,21 +268,45 @@ int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb,
 }
 EXPORT_SYMBOL(mr_fill_mroute);
 
+static bool mr_mfc_uses_dev(const struct mr_table *mrt,
+			    const struct mr_mfc *c,
+			    const struct net_device *dev)
+{
+	int ct;
+
+	for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) {
+		if (VIF_EXISTS(mrt, ct) && c->mfc_un.res.ttls[ct] < 255) {
+			const struct vif_device *vif;
+
+			vif = &mrt->vif_table[ct];
+			if (vif->dev == dev)
+				return true;
+		}
+	}
+	return false;
+}
+
 int mr_table_dump(struct mr_table *mrt, struct sk_buff *skb,
 		  struct netlink_callback *cb,
 		  int (*fill)(struct mr_table *mrt, struct sk_buff *skb,
 			      u32 portid, u32 seq, struct mr_mfc *c,
 			      int cmd, int flags),
-		  spinlock_t *lock)
+		  spinlock_t *lock, struct fib_dump_filter *filter)
 {
 	unsigned int e = 0, s_e = cb->args[1];
 	unsigned int flags = NLM_F_MULTI;
 	struct mr_mfc *mfc;
 	int err;
 
+	if (filter->filter_set)
+		flags |= NLM_F_DUMP_FILTERED;
+
 	list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) {
 		if (e < s_e)
 			goto next_entry;
+		if (filter->dev &&
+		    !mr_mfc_uses_dev(mrt, mfc, filter->dev))
+			goto next_entry;
 
 		err = fill(mrt, skb, NETLINK_CB(cb->skb).portid,
 			   cb->nlh->nlmsg_seq, mfc, RTM_NEWROUTE, flags);
@@ -298,6 +322,9 @@ next_entry:
 	list_for_each_entry(mfc, &mrt->mfc_unres_queue, list) {
 		if (e < s_e)
 			goto next_entry2;
+		if (filter->dev &&
+		    !mr_mfc_uses_dev(mrt, mfc, filter->dev))
+			goto next_entry2;
 
 		err = fill(mrt, skb, NETLINK_CB(cb->skb).portid,
 			   cb->nlh->nlmsg_seq, mfc, RTM_NEWROUTE, flags);
@@ -316,6 +343,7 @@ out:
 	cb->args[1] = e;
 	return err;
 }
+EXPORT_SYMBOL(mr_table_dump);
 
 int mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb,
 		     struct mr_table *(*iter)(struct net *net,
@@ -324,19 +352,28 @@ int mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb,
 				 struct sk_buff *skb,
 				 u32 portid, u32 seq, struct mr_mfc *c,
 				 int cmd, int flags),
-		     spinlock_t *lock)
+		     spinlock_t *lock, struct fib_dump_filter *filter)
 {
 	unsigned int t = 0, s_t = cb->args[0];
 	struct net *net = sock_net(skb->sk);
 	struct mr_table *mrt;
 	int err;
 
+	/* multicast does not track protocol or have route type other
+	 * than RTN_MULTICAST
+	 */
+	if (filter->filter_set) {
+		if (filter->protocol || filter->flags ||
+		    (filter->rt_type && filter->rt_type != RTN_MULTICAST))
+			return skb->len;
+	}
+
 	rcu_read_lock();
 	for (mrt = iter(net, NULL); mrt; mrt = iter(net, mrt)) {
 		if (t < s_t)
 			goto next_table;
 
-		err = mr_table_dump(mrt, skb, cb, fill, lock);
+		err = mr_table_dump(mrt, skb, cb, fill, lock, filter);
 		if (err < 0)
 			break;
 next_table: