Subject: [PATCH net-next 2/9] net/ipv4: Plumb support for filtering route dumps

From: David Ahern <[email-masked]>
Date: Thu, 11 Oct 2018 08:06:20 -0700

From: David Ahern <[email-masked]>

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

Signed-off-by: David Ahern <[email-masked]>
---
 include/net/ip_fib.h    |  2 +-
 net/ipv4/fib_frontend.c |  5 ++++-
 net/ipv4/fib_trie.c     | 37 ++++++++++++++++++++++++++-----------
 3 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 9dde41ad02a1..68967f4bd024 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -238,7 +238,7 @@ 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 d0fb9b7efa27..1528b0919951 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -866,10 +866,13 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
 		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..237c9f72b265 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2003,12 +2003,17 @@ 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)
 {
+	unsigned int flags = NLM_F_MULTI;
 	__be32 xkey = htonl(l->key);
 	struct fib_alias *fa;
 	int i, s_i;
 
+	if (filter->filter_set)
+		flags |= NLM_F_DUMP_FILTERED;
+
 	s_i = cb->args[4];
 	i = 0;
 
@@ -2016,25 +2021,35 @@ 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->filter_set) {
+			if (filter->rt_type && fa->fa_type != filter->rt_type)
+				goto next;
+
+			if ((filter->protocol &&
+			     fa->fa_info->fib_protocol != filter->protocol))
+				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,
 				    tb->tb_id, fa->fa_type,
 				    xkey, KEYLENGTH - fa->fa_slen,
-				    fa->fa_tos, fa->fa_info, NLM_F_MULTI);
+				    fa->fa_tos, fa->fa_info, flags);
 		if (err < 0) {
 			cb->args[4] = i;
 			return err;
 		}
+next:
 		i++;
 	}
 
@@ -2044,7 +2059,7 @@ 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 +2072,7 @@ 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