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

[David Ahern]

From: David Ahern <dsah...@gmail.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 <dsah...@gmail.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