net: Add struct for fib dump filter

Add struct fib_dump_filter for options on limiting which routes are
returned in a dump request. The current list is table id, protocol,
route type, rtm_flags and nexthop device index. struct net is needed
to lookup the net_device from the index.

Declare the filter for each route dump handler and plumb the new
arguments from dump handlers to ip_valid_fib_dump_req.

Signed-off-by: David Ahern <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/ip6_route.h

···
 	struct sk_buff *skb;
 	struct netlink_callback *cb;
 	struct net *net;
+	struct fib_dump_filter filter;
 };
 
 int rt6_dump_route(struct fib6_info *f6i, void *p_arg);

include/net/ip_fib.h

···
 	unsigned long		__data[0];
 };
 
+struct fib_dump_filter {
+	u32			table_id;
+	/* filter_set is an optimization that an entry is set */
+	bool			filter_set;
+	unsigned char		protocol;
+	unsigned char		rt_type;
+	unsigned int		flags;
+	struct net_device	*dev;
+};
+
 int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
 		     struct fib_result *res, int fib_flags);
 int fib_table_insert(struct net *, struct fib_table *, struct fib_config *,
···
 
 u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr);
 
-int ip_valid_fib_dump_req(const struct nlmsghdr *nlh,
+int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
+			  struct fib_dump_filter *filter,
 			  struct netlink_ext_ack *extack);
 #endif  /* _NET_FIB_H */

net/ipv4/fib_frontend.c

···
 	return err;
 }
 
-int ip_valid_fib_dump_req(const struct nlmsghdr *nlh,
+int ip_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
+			  struct fib_dump_filter *filter,
 			  struct netlink_ext_ack *extack)
 {
 	struct rtmsg *rtm;
···
 {
 	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
+	struct fib_dump_filter filter = {};
 	unsigned int h, s_h;
 	unsigned int e = 0, s_e;
 	struct fib_table *tb;
···
 	int dumped = 0, err;
 
 	if (cb->strict_check) {
-		err = ip_valid_fib_dump_req(nlh, cb->extack);
+		err = ip_valid_fib_dump_req(net, nlh, &filter, cb->extack);
 		if (err < 0)
 			return err;
 	}

net/ipv4/ipmr.c

···
 
 static int ipmr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	if (cb->strict_check) {
-		int err = ip_valid_fib_dump_req(cb->nlh, cb->extack);
+	struct fib_dump_filter filter = {};
 
+	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;
 	}

net/ipv6/ip6_fib.c

···
 {
 	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
+	struct rt6_rtnl_dump_arg arg = {};
 	unsigned int h, s_h;
 	unsigned int e = 0, s_e;
-	struct rt6_rtnl_dump_arg arg;
 	struct fib6_walker *w;
 	struct fib6_table *tb;
 	struct hlist_head *head;
 	int res = 0;
 
 	if (cb->strict_check) {
-		int err = ip_valid_fib_dump_req(nlh, cb->extack);
+		int err;
 
+		err = ip_valid_fib_dump_req(net, nlh, &arg.filter, cb->extack);
 		if (err < 0)
 			return err;
 	}

net/ipv6/ip6mr.c

···
 static int ip6mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	const struct nlmsghdr *nlh = cb->nlh;
+	struct fib_dump_filter filter = {};
 
 	if (cb->strict_check) {
-		int err = ip_valid_fib_dump_req(nlh, cb->extack);
+		int err;
 
+		err = ip_valid_fib_dump_req(sock_net(skb->sk), nlh,
+					    &filter, cb->extack);
 		if (err < 0)
 			return err;
 	}

net/mpls/af_mpls.c

···
 }
 
 #if IS_ENABLED(CONFIG_INET)
-static int mpls_valid_fib_dump_req(const struct nlmsghdr *nlh,
+static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
+				   struct fib_dump_filter *filter,
 				   struct netlink_ext_ack *extack)
 {
-	return ip_valid_fib_dump_req(nlh, extack);
+	return ip_valid_fib_dump_req(net, nlh, filter, extack);
 }
 #else
-static int mpls_valid_fib_dump_req(const struct nlmsghdr *nlh,
+static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
+				   struct fib_dump_filter *filter,
 				   struct netlink_ext_ack *extack)
 {
 	struct rtmsg *rtm;
···
 	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
 	struct mpls_route __rcu **platform_label;
+	struct fib_dump_filter filter = {};
 	size_t platform_labels;
 	unsigned int index;
 
 	ASSERT_RTNL();
 
 	if (cb->strict_check) {
-		int err = mpls_valid_fib_dump_req(nlh, cb->extack);
+		int err;
 
+		err = mpls_valid_fib_dump_req(net, nlh, &filter, cb->extack);
 		if (err < 0)
 			return err;
 	}