bpf: sockmap, refactor sockmap routines to work with hashmap

This patch only refactors the existing sockmap code. This will allow
much of the psock initialization code path and bpf helper codes to
work for both sockmap bpf map types that are backed by an array, the
currently supported type, and the new hash backed bpf map type
sockhash.

Most the fallout comes from three changes,

  - Pushing bpf programs into an independent structure so we
    can use it from the htab struct in the next patch.
  - Generalizing helpers to use void *key instead of the hardcoded
    u32.
  - Instead of passing map/key through the metadata we now do
    the lookup inline. This avoids storing the key in the metadata
    which will be useful when keys can be longer than 4 bytes. We
    rename the sk pointers to sk_redir at this point as well to
    avoid any confusion between the current sk pointer and the
    redirect pointer sk_redir.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 8 insertions, 23 deletions

diff --git a/net/core/filter.c b/net/core/filter.c
index ca60d28..61a3ed6 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2083,9 +2083,10 @@ BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
 	if (unlikely(flags & ~(BPF_F_INGRESS)))
 		return SK_DROP;
 
-	tcb->bpf.key = key;
 	tcb->bpf.flags = flags;
-	tcb->bpf.map = map;
+	tcb->bpf.sk_redir = __sock_map_lookup_elem(map, key);
+	if (!tcb->bpf.sk_redir)
+		return SK_DROP;
 
 	return SK_PASS;
 }
@@ -2093,16 +2094,8 @@ BPF_CALL_4(bpf_sk_redirect_map, struct sk_buff *, skb,
 struct sock *do_sk_redirect_map(struct sk_buff *skb)
 {
 	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
-	struct sock *sk = NULL;
-
-	if (tcb->bpf.map) {
-		sk = __sock_map_lookup_elem(tcb->bpf.map, tcb->bpf.key);
 
-		tcb->bpf.key = 0;
-		tcb->bpf.map = NULL;
-	}
-
-	return sk;
+	return tcb->bpf.sk_redir;
 }
 
 static const struct bpf_func_proto bpf_sk_redirect_map_proto = {
@@ -2122,25 +2115,17 @@ BPF_CALL_4(bpf_msg_redirect_map, struct sk_msg_buff *, msg,
 	if (unlikely(flags & ~(BPF_F_INGRESS)))
 		return SK_DROP;
 
-	msg->key = key;
 	msg->flags = flags;
-	msg->map = map;
+	msg->sk_redir = __sock_map_lookup_elem(map, key);
+	if (!msg->sk_redir)
+		return SK_DROP;
 
 	return SK_PASS;
 }
 
 struct sock *do_msg_redirect_map(struct sk_msg_buff *msg)
 {
-	struct sock *sk = NULL;
-
-	if (msg->map) {
-		sk = __sock_map_lookup_elem(msg->map, msg->key);
-
-		msg->key = 0;
-		msg->map = NULL;
-	}
-
-	return sk;
+	return msg->sk_redir;
 }
 
 static const struct bpf_func_proto bpf_msg_redirect_map_proto = {