Messages in this thread | | | From | Alexander Lobakin <> | Subject | Re: [PATCH net-next 1/2] IPv6/GRO: generic helper to remove temporary HBH/jumbo header in driver | Date | Wed, 23 Nov 2022 17:38:25 +0100 |
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From: Coco Li <lixiaoyan@google.com> Date: Tue, 22 Nov 2022 15:27:39 -0800
> 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 | 33 +++++++++++++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/include/net/ipv6.h b/include/net/ipv6.h > index d383c895592a..a11d58c85c05 100644 > --- a/include/net/ipv6.h > +++ b/include/net/ipv6.h > @@ -500,6 +500,39 @@ 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;
err = skb_cow_head(skb, 0); if (err) return err;
Alternatively, if you want to keep it simple, make the function bool and return false on `if (skb_cow_head(skb, 0)` and true otherwise.
> + > + /* Remove the HBH header. > + * Layout: [Ethernet header][IPv6 header][HBH][L4 Header] > + */ > + memmove(skb->data + hophdr_len, > + skb->data,
This can fit into the previous line.
> + ETH_HLEN + sizeof(struct ipv6hdr));
Not correct at this point. I assume you took the implementation from ip6_offload.c[0], but ::gso_segment() and ::ndo_start_xmit() are two different entry points. Here you may have not only Eth header, but also VLAN, MPLS and whatnot. Correct way would be:
memmove(skb_mac_header(skb) + hophdr_len, skb_mac_header(skb), ipv6_hdr(skb) - skb_mac_header(skb) + sizeof(struct ipv6hdr));
> + > + skb->data += hophdr_len; > + skb->len -= hophdr_len; > + skb->network_header += hophdr_len;
skb->mac_header also needs to be adjusted, the fact that it's equal to skb->data at the entry of ::ndo_start_xmit() doesn't mean anything.
> + > + h6 = ipv6_hdr(skb); > + h6->nexthdr = nexthdr; > + > + return 0; > +}
Please switch all the places where the same logics is used to your new helper.
> + > static inline bool ipv6_accept_ra(struct inet6_dev *idev) > { > /* If forwarding is enabled, RA are not accepted unless the special > -- > 2.38.1.584.g0f3c55d4c2-goog
Thanks, Olek
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