diff mbox series

[net-next,v5,1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver

Message ID 20221207225435.1273226-1-lixiaoyan@google.com
State New
Headers
Series [net-next,v5,1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver |

Commit Message

Coco Li Dec. 7, 2022, 10:54 p.m. UTC 
  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.

Tested:
Compiled and ran with ethtool -K eth1 tso off
Could send Big TCP packets

Signed-off-by: Coco Li <lixiaoyan@google.com>
---
 include/net/ipv6.h     | 36 ++++++++++++++++++++++++++++++++++++
 net/ipv6/ip6_offload.c | 27 ++++-----------------------
 2 files changed, 40 insertions(+), 23 deletions(-)

Comments

Eric Dumazet Dec. 8, 2022, 2:21 a.m. UTC | #1 
On Wed, Dec 7, 2022 at 11:54 PM Coco Li <lixiaoyan@google.com> wrote:
>
> 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.
>
> Tested:
> Compiled and ran with ethtool -K eth1 tso off
> Could send Big TCP packets
>
> Signed-off-by: Coco Li <lixiaoyan@google.com>
> ---
>  include/net/ipv6.h     | 36 ++++++++++++++++++++++++++++++++++++
>  net/ipv6/ip6_offload.c | 27 ++++-----------------------
>  2 files changed, 40 insertions(+), 23 deletions(-)
>
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index d383c895592a..6dcf93a1ec14 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -500,6 +500,42 @@ 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;

ipv6_has_hopopt_jumbo() had a stronger condition already.

if (skb_network_offset(skb) +
     sizeof(struct ipv6hdr) +
     sizeof(struct hop_jumbo_hdr) > skb_headlen(skb))
        return 0;

So this !pskb_may_pull(skb, hophdr_len) , especially if done after the
memmove(), is not needed.


> +
> +       __skb_pull(skb, hophdr_len);
> +       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
>
diff mbox series

Patch

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index d383c895592a..6dcf93a1ec14 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -500,6 +500,42 @@  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_pull(skb, hophdr_len);
+	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;