netdev - [PATCH RFC v2 net-next 23/25] net/mpls: Plumb support for filtering route dumps

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Date:   Mon,  1 Oct 2018 17:28:49 -0700
From:   David Ahern <dsahern@...nel.org>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     christian@...uner.io, jbenc@...hat.com, stephen@...workplumber.org,
        David Ahern <dsahern@...il.com>
Subject: [PATCH RFC v2 net-next 23/25] net/mpls: Plumb support for filtering route dumps

From: David Ahern <dsahern@...il.com>

Implement kernel side filtering of routes by egress device index and
protocol. MPLS uses only a single table and route type.

Signed-off-by: David Ahern <dsahern@...il.com>
---
 net/mpls/af_mpls.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index f94d1db63eb5..4dd8a2a026e7 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -2031,6 +2031,28 @@ static int mpls_dump_route(struct sk_buff *skb, u32 portid, u32 seq, int event,
 	return -EMSGSIZE;
 }
 
+static bool mpls_rt_uses_dev(struct mpls_route *rt,
+			     const struct net_device *dev)
+{
+	struct net_device *nh_dev;
+
+	if (rt->rt_nhn == 1) {
+		struct mpls_nh *nh = rt->rt_nh;
+
+		nh_dev = rtnl_dereference(nh->nh_dev);
+		if (dev == nh_dev)
+			return true;
+	} else {
+		for_nexthops(rt) {
+			nh_dev = rtnl_dereference(nh->nh_dev);
+			if (nh_dev == dev)
+				return true;
+		} endfor_nexthops(rt);
+	}
+
+	return false;
+}
+
 static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
@@ -2039,6 +2061,7 @@ static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
 	struct fib_dump_filter filter = {};
 	size_t platform_labels;
 	unsigned int index;
+	int err;
 
 	ASSERT_RTNL();
 
@@ -2047,6 +2070,15 @@ static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
 
 		if (err)
 			return err;
+
+		/* for MPLS, there is only 1 table with fixed type, scope
+		 * tos and flags. If any of these are set in the filter then
+		 * return nothing
+		 */
+		if ((filter.table_id && filter.table_id != RT_TABLE_MAIN) ||
+		    (filter.rt_type && filter.rt_type != RTN_UNICAST) ||
+		     filter.scope || filter.tos || filter.flags)
+			return 0;
 	}
 
 	index = cb->args[0];
@@ -2055,20 +2087,41 @@ static int mpls_dump_routes(struct sk_buff *skb, struct netlink_callback *cb)
 
 	platform_label = rtnl_dereference(net->mpls.platform_label);
 	platform_labels = net->mpls.platform_labels;
+
+	rcu_read_lock();
+
+	if (filter.ifindex) {
+		filter.dev = dev_get_by_index_rcu(net, filter.ifindex);
+		if (!filter.dev) {
+			err = -ENODEV;
+			goto out_err;
+		}
+	}
+
 	for (; index < platform_labels; index++) {
 		struct mpls_route *rt;
+
 		rt = rtnl_dereference(platform_label[index]);
 		if (!rt)
 			continue;
 
+		if (filter.protocol && rt->rt_protocol != filter.protocol)
+			continue;
+
+		if (filter.dev && !mpls_rt_uses_dev(rt, filter.dev))
+			continue;
+
 		if (mpls_dump_route(skb, NETLINK_CB(cb->skb).portid,
 				    cb->nlh->nlmsg_seq, RTM_NEWROUTE,
 				    index, rt, NLM_F_MULTI) < 0)
 			break;
 	}
 	cb->args[0] = index;
+	err = skb->len;
 
-	return skb->len;
+out_err:
+	rcu_read_unlock();
+	return err;
 }
 
 static inline size_t lfib_nlmsg_size(struct mpls_route *rt)
-- 
2.11.0