Subject: [PATCH 2/4] net_sched: fix mirrored packets checksum

From: WANG Cong <[email-masked]>
Date: Thu, 30 Jun 2016 10:15:22 -0700

[ Upstream commit 82a31b9231f02d9c1b7b290a46999d517b0d312a ]

Similar to commit 9b368814b336 ("net: fix bridge multicast packet checksum validation")
we need to fixup the checksum for CHECKSUM_COMPLETE when
pushing skb on RX path. Otherwise we get similar splats.

Cc: Jamal Hadi Salim <[email-masked]>
Cc: Tom Herbert <[email-masked]>
Signed-off-by: Cong Wang <[email-masked]>
Acked-by: Jamal Hadi Salim <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 include/linux/skbuff.h | 19 +++++++++++++++++++
 net/core/skbuff.c      | 18 ------------------
 net/sched/act_mirred.c |  2 +-
 3 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b3bb990..d443d9a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2774,6 +2774,25 @@ static inline void skb_postpush_rcsum(struct sk_buff *skb,
 }
 
 /**
+ *	skb_push_rcsum - push skb and update receive checksum
+ *	@skb: buffer to update
+ *	@len: length of data pulled
+ *
+ *	This function performs an skb_push on the packet and updates
+ *	the CHECKSUM_COMPLETE checksum.  It should be used on
+ *	receive path processing instead of skb_push unless you know
+ *	that the checksum difference is zero (e.g., a valid IP header)
+ *	or you are setting ip_summed to CHECKSUM_NONE.
+ */
+static inline unsigned char *skb_push_rcsum(struct sk_buff *skb,
+					    unsigned int len)
+{
+	skb_push(skb, len);
+	skb_postpush_rcsum(skb, skb->data, len);
+	return skb->data;
+}
+
+/**
  *	pskb_trim_rcsum - trim received skb and update checksum
  *	@skb: buffer to trim
  *	@len: new length
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 9835d9a..4968b5d 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2948,24 +2948,6 @@ int skb_append_pagefrags(struct sk_buff *skb, struct page *page,
 EXPORT_SYMBOL_GPL(skb_append_pagefrags);
 
 /**
- *	skb_push_rcsum - push skb and update receive checksum
- *	@skb: buffer to update
- *	@len: length of data pulled
- *
- *	This function performs an skb_push on the packet and updates
- *	the CHECKSUM_COMPLETE checksum.  It should be used on
- *	receive path processing instead of skb_push unless you know
- *	that the checksum difference is zero (e.g., a valid IP header)
- *	or you are setting ip_summed to CHECKSUM_NONE.
- */
-static unsigned char *skb_push_rcsum(struct sk_buff *skb, unsigned len)
-{
-	skb_push(skb, len);
-	skb_postpush_rcsum(skb, skb->data, len);
-	return skb->data;
-}
-
-/**
  *	skb_pull_rcsum - pull skb and update receive checksum
  *	@skb: buffer to update
  *	@len: length of data pulled
diff --git a/net/sched/act_mirred.c b/net/sched/act_mirred.c
index 32fcdec..e384d6a 100644
--- a/net/sched/act_mirred.c
+++ b/net/sched/act_mirred.c
@@ -170,7 +170,7 @@ static int tcf_mirred(struct sk_buff *skb, const struct tc_action *a,
 
 	if (!(at & AT_EGRESS)) {
 		if (m->tcfm_ok_push)
-			skb_push(skb2, skb->mac_len);
+			skb_push_rcsum(skb2, skb->mac_len);
 	}
 
 	/* mirror is always swallowed */
-- 
2.1.0