Subject: [PATCH net-next 3/9] net/ipv6: Plumb support for filtering route dumps

From: David Ahern <[email-masked]>
Date: Thu, 11 Oct 2018 08:06:21 -0700

From: David Ahern <[email-masked]>

Implement kernel side filtering of routes by table id, egress device
index, protocol, and route type.

Move the existing route flags check for prefix only routes to the new
filter.

Signed-off-by: David Ahern <[email-masked]>
---
 net/ipv6/ip6_fib.c |  9 +++++++++
 net/ipv6/route.c   | 40 ++++++++++++++++++++++++++++++++--------
 2 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 6a169794a674..dd6a43874192 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -580,6 +580,11 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 		err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb->extack);
 		if (err < 0)
 			return err;
+	} else if (nlmsg_len(nlh) >= sizeof(struct rtmsg)) {
+		struct rtmsg *rtm = nlmsg_data(nlh);
+
+		if (rtm->rtm_flags & RTM_F_PREFIX)
+			arg.filter.flags = RTM_F_PREFIX;
 	}
 
 	s_h = cb->args[0];
@@ -616,6 +621,10 @@ static int inet6_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 		hlist_for_each_entry_rcu(tb, head, tb6_hlist) {
 			if (e < s_e)
 				goto next;
+			if (arg.filter.table_id &&
+			    arg.filter.table_id != tb->tb6_id)
+				goto next;
+
 			res = fib6_dump_table(tb, skb, cb);
 			if (res != 0)
 				goto out;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index bf4cd647d8b8..8ed2e7462657 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4763,28 +4763,52 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb,
 	return -EMSGSIZE;
 }
 
+static bool fib6_info_uses_dev(const struct fib6_info *f6i,
+			       const struct net_device *dev)
+{
+	if (f6i->fib6_nh.nh_dev == dev)
+		return true;
+
+	if (f6i->fib6_nsiblings) {
+		struct fib6_info *sibling, *next_sibling;
+
+		list_for_each_entry_safe(sibling, next_sibling,
+					 &f6i->fib6_siblings, fib6_siblings) {
+			if (sibling->fib6_nh.nh_dev == dev)
+				return true;
+		}
+	}
+
+	return false;
+}
+
 int rt6_dump_route(struct fib6_info *rt, void *p_arg)
 {
 	struct rt6_rtnl_dump_arg *arg = (struct rt6_rtnl_dump_arg *) p_arg;
+	struct fib_dump_filter *filter = &arg->filter;
+	unsigned int flags = NLM_F_MULTI;
 	struct net *net = arg->net;
 
 	if (rt == net->ipv6.fib6_null_entry)
 		return 0;
 
-	if (nlmsg_len(arg->cb->nlh) >= sizeof(struct rtmsg)) {
-		struct rtmsg *rtm = nlmsg_data(arg->cb->nlh);
-
-		/* user wants prefix routes only */
-		if (rtm->rtm_flags & RTM_F_PREFIX &&
-		    !(rt->fib6_flags & RTF_PREFIX_RT)) {
-			/* success since this is not a prefix route */
+	if ((filter->flags & RTM_F_PREFIX) &&
+	    !(rt->fib6_flags & RTF_PREFIX_RT)) {
+		/* success since this is not a prefix route */
+		return 1;
+	}
+	if (filter->filter_set) {
+		if ((filter->rt_type && rt->fib6_type != filter->rt_type) ||
+		    (filter->dev && !fib6_info_uses_dev(rt, filter->dev)) ||
+		    (filter->protocol && rt->fib6_protocol != filter->protocol)) {
 			return 1;
 		}
+		flags |= NLM_F_DUMP_FILTERED;
 	}
 
 	return rt6_fill_node(net, arg->skb, rt, NULL, NULL, NULL, 0,
 			     RTM_NEWROUTE, NETLINK_CB(arg->cb->skb).portid,
-			     arg->cb->nlh->nlmsg_seq, NLM_F_MULTI);
+			     arg->cb->nlh->nlmsg_seq, flags);
 }
 
 static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh,
-- 
2.11.0