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* [RFC net-next v4 1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver
@ 2022-12-02 22:12 Coco Li
  2022-12-02 22:12 ` [RFC net-next v4 2/2] bnxt: Use generic HBH removal helper in tx path Coco Li
                   ` (2 more replies)
  0 siblings, 3 replies; 8+ messages in thread
From: Coco Li @ 2022-12-02 22:12 UTC (permalink / raw)
  To: David S. Miller, Hideaki YOSHIFUJI, David Ahern, Eric Dumazet,
	Jakub Kicinski, Paolo Abeni, Michael Chan
  Cc: netdev, linux-kernel, Coco Li

IPv6/TCP and GRO stacks can build big TCP packets with an added
temporary Hop By Hop header.

Is GSO is not involved, then the temporary header needs to be removed in
the driver. This patch provides a generic helper for drivers that need
to modify their headers in place.

Signed-off-by: Coco Li <lixiaoyan@google.com>
---
 include/net/ipv6.h     | 35 +++++++++++++++++++++++++++++++++++
 net/ipv6/ip6_offload.c | 27 ++++-----------------------
 2 files changed, 39 insertions(+), 23 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index d383c895592a..08adec74f067 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -500,6 +500,41 @@ static inline int ipv6_has_hopopt_jumbo(const struct sk_buff *skb)
 	return jhdr->nexthdr;
 }
 
+/* Return 0 if HBH header is successfully removed
+ * Or if HBH removal is unnecessary (packet is not big TCP)
+ * Return error to indicate dropping the packet
+ */
+static inline int ipv6_hopopt_jumbo_remove(struct sk_buff *skb)
+{
+	const int hophdr_len = sizeof(struct hop_jumbo_hdr);
+	int nexthdr = ipv6_has_hopopt_jumbo(skb);
+	struct ipv6hdr *h6;
+
+	if (!nexthdr)
+		return 0;
+
+	if (skb_cow_head(skb, 0))
+		return -1;
+
+	/* Remove the HBH header.
+	 * Layout: [Ethernet header][IPv6 header][HBH][L4 Header]
+	 */
+	memmove(skb_mac_header(skb) + hophdr_len, skb_mac_header(skb),
+		skb_network_header(skb) - skb_mac_header(skb) +
+		sizeof(struct ipv6hdr));
+
+	if (unlikely(!pskb_may_pull(skb, hophdr_len)))
+		return -1;
+
+	skb->network_header += hophdr_len;
+	skb->mac_header += hophdr_len;
+
+	h6 = ipv6_hdr(skb);
+	h6->nexthdr = nexthdr;
+
+	return 0;
+}
+
 static inline bool ipv6_accept_ra(struct inet6_dev *idev)
 {
 	/* If forwarding is enabled, RA are not accepted unless the special
diff --git a/net/ipv6/ip6_offload.c b/net/ipv6/ip6_offload.c
index 3ee345672849..00dc2e3b0184 100644
--- a/net/ipv6/ip6_offload.c
+++ b/net/ipv6/ip6_offload.c
@@ -77,7 +77,7 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 	struct sk_buff *segs = ERR_PTR(-EINVAL);
 	struct ipv6hdr *ipv6h;
 	const struct net_offload *ops;
-	int proto, nexthdr;
+	int proto, err;
 	struct frag_hdr *fptr;
 	unsigned int payload_len;
 	u8 *prevhdr;
@@ -87,28 +87,9 @@ static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 	bool gso_partial;
 
 	skb_reset_network_header(skb);
-	nexthdr = ipv6_has_hopopt_jumbo(skb);
-	if (nexthdr) {
-		const int hophdr_len = sizeof(struct hop_jumbo_hdr);
-		int err;
-
-		err = skb_cow_head(skb, 0);
-		if (err < 0)
-			return ERR_PTR(err);
-
-		/* remove the HBH header.
-		 * Layout: [Ethernet header][IPv6 header][HBH][TCP header]
-		 */
-		memmove(skb_mac_header(skb) + hophdr_len,
-			skb_mac_header(skb),
-			ETH_HLEN + sizeof(struct ipv6hdr));
-		skb->data += hophdr_len;
-		skb->len -= hophdr_len;
-		skb->network_header += hophdr_len;
-		skb->mac_header += hophdr_len;
-		ipv6h = (struct ipv6hdr *)skb->data;
-		ipv6h->nexthdr = nexthdr;
-	}
+	err = ipv6_hopopt_jumbo_remove(skb);
+	if (err)
+		return ERR_PTR(err);
 	nhoff = skb_network_header(skb) - skb_mac_header(skb);
 	if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 		goto out;
-- 
2.39.0.rc0.267.gcb52ba06e7-goog


^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2022-12-05 22:48 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-12-02 22:12 [RFC net-next v4 1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver Coco Li
2022-12-02 22:12 ` [RFC net-next v4 2/2] bnxt: Use generic HBH removal helper in tx path Coco Li
2022-12-03  1:20   ` kernel test robot
2022-12-03 19:12   ` kernel test robot
2022-12-05  5:14   ` Eric Dumazet
2022-12-05 22:47     ` Michael Chan
2022-12-05  2:23 ` [RFC net-next v4 1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver Michael Chan
2022-12-05  5:11 ` Eric Dumazet

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