Merge branch 'bpf-next'

Daniel Borkmann says:

====================
BPF update

Fixes a csum issue on ingress. As mentioned previously, net-next
seems just fine imho. Later on, will follow up with couple of
replacements like ovs_skb_postpush_rcsum() etc.

Thanks!

v1 -> v2:
  - Added patch 1 with helper
  - Implemented Hannes' idea to just use csum_partial, thanks!
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 40 insertions, 9 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 6b6bd42d6134..07f9ccd28654 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2805,6 +2805,23 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb,
 
 unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len);
 
+static inline void skb_postpush_rcsum(struct sk_buff *skb,
+				      const void *start, unsigned int len)
+{
+	/* For performing the reverse operation to skb_postpull_rcsum(),
+	 * we can instead of ...
+	 *
+	 *   skb->csum = csum_add(skb->csum, csum_partial(start, len, 0));
+	 *
+	 * ... just use this equivalent version here to save a few
+	 * instructions. Feeding csum of 0 in csum_partial() and later
+	 * on adding skb->csum is equivalent to feed skb->csum in the
+	 * first place.
+	 */
+	if (skb->ip_summed == CHECKSUM_COMPLETE)
+		skb->csum = csum_partial(start, len, skb->csum);
+}
+
 /**
  *	pskb_trim_rcsum - trim received skb and update checksum
  *	@skb: buffer to trim
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index b2a8e6338576..636a362a0e03 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -407,6 +407,15 @@ bool tcf_destroy(struct tcf_proto *tp, bool force);
 void tcf_destroy_chain(struct tcf_proto __rcu **fl);
 int skb_do_redirect(struct sk_buff *);
 
+static inline bool skb_at_tc_ingress(const struct sk_buff *skb)
+{
+#ifdef CONFIG_NET_CLS_ACT
+	return G_TC_AT(skb->tc_verd) & AT_INGRESS;
+#else
+	return false;
+#endif
+}
+
 /* Reset all TX qdiscs greater then index of a device.  */
 static inline void qdisc_reset_all_tx_gt(struct net_device *dev, unsigned int i)
 {
diff --git a/net/core/filter.c b/net/core/filter.c
index 35e6fed28709..0db92b5e2cbf 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1368,8 +1368,9 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags)
 		/* skb_store_bits cannot return -EFAULT here */
 		skb_store_bits(skb, offset, ptr, len);
 
-	if (BPF_RECOMPUTE_CSUM(flags) && skb->ip_summed == CHECKSUM_COMPLETE)
-		skb->csum = csum_add(skb->csum, csum_partial(ptr, len, 0));
+	if (BPF_RECOMPUTE_CSUM(flags))
+		skb_postpush_rcsum(skb, ptr, len);
+
 	return 0;
 }
 
@@ -1525,8 +1526,12 @@ static u64 bpf_clone_redirect(u64 r1, u64 ifindex, u64 flags, u64 r4, u64 r5)
 	if (unlikely(!skb2))
 		return -ENOMEM;
 
-	if (BPF_IS_REDIRECT_INGRESS(flags))
+	if (BPF_IS_REDIRECT_INGRESS(flags)) {
+		if (skb_at_tc_ingress(skb2))
+			skb_postpush_rcsum(skb2, skb_mac_header(skb2),
+					   skb2->mac_len);
 		return dev_forward_skb(dev, skb2);
+	}
 
 	skb2->dev = dev;
 	skb_sender_cpu_clear(skb2);
@@ -1569,8 +1574,12 @@ int skb_do_redirect(struct sk_buff *skb)
 		return -EINVAL;
 	}
 
-	if (BPF_IS_REDIRECT_INGRESS(ri->flags))
+	if (BPF_IS_REDIRECT_INGRESS(ri->flags)) {
+		if (skb_at_tc_ingress(skb))
+			skb_postpush_rcsum(skb, skb_mac_header(skb),
+					   skb->mac_len);
 		return dev_forward_skb(dev, skb);
+	}
 
 	skb->dev = dev;
 	skb_sender_cpu_clear(skb);
diff --git a/net/sched/cls_bpf.c b/net/sched/cls_bpf.c
index 5faaa5425f7b..b3c8bb4aeef5 100644
--- a/net/sched/cls_bpf.c
+++ b/net/sched/cls_bpf.c
@@ -79,12 +79,8 @@ static int cls_bpf_classify(struct sk_buff *skb, const struct tcf_proto *tp,
 			    struct tcf_result *res)
 {
 	struct cls_bpf_head *head = rcu_dereference_bh(tp->root);
+	bool at_ingress = skb_at_tc_ingress(skb);
 	struct cls_bpf_prog *prog;
-#ifdef CONFIG_NET_CLS_ACT
-	bool at_ingress = G_TC_AT(skb->tc_verd) & AT_INGRESS;
-#else
-	bool at_ingress = false;
-#endif
 	int ret = -1;
 
 	if (unlikely(!skb_mac_header_was_set(skb)))