Subject: [PATCH RFC v2 net-next 21/25] net/ipv4: Plumb support for filtering route dumps

From: David Ahern <[email-masked]>
Date: Mon, 1 Oct 2018 17:28:47 -0700

From: David Ahern <[email-masked]>

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

Signed-off-by: David Ahern <[email-masked]>
---
 include/net/ip_fib.h    |  2 +-
 net/ipv4/fib_frontend.c | 13 ++++++++++++-
 net/ipv4/fib_trie.c     | 33 ++++++++++++++++++++++-----------
 3 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index d0cd838ca00c..e064c37a2a9f 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -240,7 +240,7 @@ int fib_table_insert(struct net *, struct fib_table *, struct fib_config *,
 int fib_table_delete(struct net *, struct fib_table *, struct fib_config *,
 		     struct netlink_ext_ack *extack);
 int fib_table_dump(struct fib_table *table, struct sk_buff *skb,
-		   struct netlink_callback *cb);
+		   struct netlink_callback *cb, struct fib_dump_filter *filter);
 int fib_table_flush(struct net *net, struct fib_table *table);
 struct fib_table *fib_trie_unmerge(struct fib_table *main_tb);
 void fib_table_flush_external(struct fib_table *table);
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 9d872a4900cd..a3f4073e509a 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -861,16 +861,27 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 
 	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 (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
 		e = 0;
 		head = &net->ipv4.fib_table_hash[h];
 		hlist_for_each_entry_rcu(tb, head, tb_hlist) {
 			if (e < s_e)
 				goto next;
+			if (filter.table_id && filter.table_id != tb->tb_id)
+				goto next;
+
 			if (dumped)
 				memset(&cb->args[2], 0, sizeof(cb->args) -
 						 2 * sizeof(cb->args[0]));
-			err = fib_table_dump(tb, skb, cb);
+			err = fib_table_dump(tb, skb, cb, &filter);
 			if (err < 0) {
 				if (likely(skb->len))
 					goto out;
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 5bc0c89e81e4..0e7b4233851a 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2003,7 +2003,8 @@ void fib_free_table(struct fib_table *tb)
 }
 
 static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
-			     struct sk_buff *skb, struct netlink_callback *cb)
+			     struct sk_buff *skb, struct netlink_callback *cb,
+			     struct fib_dump_filter *filter)
 {
 	__be32 xkey = htonl(l->key);
 	struct fib_alias *fa;
@@ -2016,15 +2017,24 @@ static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
 	hlist_for_each_entry_rcu(fa, &l->leaf, fa_list) {
 		int err;
 
-		if (i < s_i) {
-			i++;
-			continue;
-		}
+		if (i < s_i)
+			goto next;
 
-		if (tb->tb_id != fa->tb_id) {
-			i++;
-			continue;
-		}
+		if (tb->tb_id != fa->tb_id)
+			goto next;
+
+		if ((filter->tos && fa->fa_tos != filter->tos) ||
+		    (filter->rt_type && fa->fa_type != filter->rt_type))
+			goto next;
+
+		if ((filter->protocol &&
+		     fa->fa_info->fib_protocol != filter->protocol) ||
+		    (filter->scope && fa->fa_info->fib_scope != filter->scope))
+			goto next;
+
+		if (filter->dev &&
+		    !fib_info_nh_uses_dev(fa->fa_info, filter->dev))
+			goto next;
 
 		err = fib_dump_info(skb, NETLINK_CB(cb->skb).portid,
 				    cb->nlh->nlmsg_seq, RTM_NEWROUTE,
@@ -2035,6 +2045,7 @@ static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
 			cb->args[4] = i;
 			return err;
 		}
+next:
 		i++;
 	}
 
@@ -2044,7 +2055,7 @@ static int fn_trie_dump_leaf(struct key_vector *l, struct fib_table *tb,
 
 /* rcu_read_lock needs to be hold by caller from readside */
 int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
-		   struct netlink_callback *cb)
+		   struct netlink_callback *cb, struct fib_dump_filter *filter)
 {
 	struct trie *t = (struct trie *)tb->tb_data;
 	struct key_vector *l, *tp = t->kv;
@@ -2057,7 +2068,7 @@ int fib_table_dump(struct fib_table *tb, struct sk_buff *skb,
 	while ((l = leaf_walk_rcu(&tp, key)) != NULL) {
 		int err;
 
-		err = fn_trie_dump_leaf(l, tb, skb, cb);
+		err = fn_trie_dump_leaf(l, tb, skb, cb, filter);
 		if (err < 0) {
 			cb->args[3] = key;
 			cb->args[2] = count;
-- 
2.11.0