commit 04686ef299db5ff299bfc5a4504b189e46842078
author John Fastabend <john.fastabend@gmail.com> Tue Oct 31 19:17:31 2017 -0700
committer David S. Miller <davem@davemloft.net> Wed Nov 01 11:43:50 2017 +0900
tree a370942e93babe219c14f3022f8d78f69198c328
parent 14fc0abafe159fbe8bbcfeca157ef3ba139fa75f

bpf: remove SK_REDIRECT from UAPI

Now that SK_REDIRECT is no longer a valid return code. Remove it
from the UAPI completely. Then do a namespace remapping internal
to sockmap so SK_REDIRECT is no longer externally visible.

Patchs primary change is to do a namechange from SK_REDIRECT to
__SK_REDIRECT

Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/bpf.h

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 0d7948c..7bf4c75 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -788,7 +788,6 @@
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,
-	SK_REDIRECT,
 };
 
 #define BPF_TAG_SIZE	8

kernel/bpf/sockmap.c

diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 66f00a2..dbd7b32 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -101,13 +101,19 @@
 	TCP_SKB_CB(skb)->bpf.data_end = skb->data + skb_headlen(skb);
 }
 
+enum __sk_action {
+	__SK_DROP = 0,
+	__SK_PASS,
+	__SK_REDIRECT,
+};
+
 static int smap_verdict_func(struct smap_psock *psock, struct sk_buff *skb)
 {
 	struct bpf_prog *prog = READ_ONCE(psock->bpf_verdict);
 	int rc;
 
 	if (unlikely(!prog))
-		return SK_DROP;
+		return __SK_DROP;
 
 	skb_orphan(skb);
 	/* We need to ensure that BPF metadata for maps is also cleared
@@ -122,8 +128,10 @@
 	preempt_enable();
 	skb->sk = NULL;
 
+	/* Moving return codes from UAPI namespace into internal namespace */
 	return rc == SK_PASS ?
-		(TCP_SKB_CB(skb)->bpf.map ? SK_REDIRECT : SK_PASS) : SK_DROP;
+		(TCP_SKB_CB(skb)->bpf.map ? __SK_REDIRECT : __SK_PASS) :
+		__SK_DROP;
 }
 
 static void smap_do_verdict(struct smap_psock *psock, struct sk_buff *skb)
@@ -133,7 +141,7 @@
 
 	rc = smap_verdict_func(psock, skb);
 	switch (rc) {
-	case SK_REDIRECT:
+	case __SK_REDIRECT:
 		sk = do_sk_redirect_map(skb);
 		if (likely(sk)) {
 			struct smap_psock *peer = smap_psock_sk(sk);
@@ -149,7 +157,7 @@
 			}
 		}
 	/* Fall through and free skb otherwise */
-	case SK_DROP:
+	case __SK_DROP:
 	default:
 		kfree_skb(skb);
 	}

tools/include/uapi/linux/bpf.h

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index c174971..01cc7ba 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -576,7 +576,7 @@
  *     @map: pointer to sockmap
  *     @key: key to lookup sock in map
  *     @flags: reserved for future use
- *     Return: SK_REDIRECT
+ *     Return: SK_PASS
  *
  * int bpf_sock_map_update(skops, map, key, flags)
  *	@skops: pointer to bpf_sock_ops
@@ -789,7 +789,6 @@
 enum sk_action {
 	SK_DROP = 0,
 	SK_PASS,
-	SK_REDIRECT,
 };
 
 #define BPF_TAG_SIZE	8