On 05/01/2018 12:31 PM, Toke Høiland-Jørgensen wrote:
> Could you comment on specifically what you believe is broken in this,
> please, so I can fix it in the same iteration?
>
Apart from the various pskb_may_pull() this helper should not change skb layout.
Ideally, the skb should be const and you would use skb_header_pointer() to make
clear
you do not ever write this skb.
This would make the reviewer job pretty easy, as no side effect can possibly
happen.
> +static inline struct tcphdr *cake_get_tcphdr(struct sk_buff *skb)
> +{
> + struct ipv6hdr *ipv6h;
> + struct iphdr *iph;
> +
> + /* check IPv6 header size immediately, since for IPv4 we need the space
> + * for the TCP header anyway
> + */
> + if (!pskb_may_pull(skb, skb_network_offset(skb) +
> + sizeof(struct ipv6hdr)))
> + return NULL;
> +
> + iph = ip_hdr(skb);
> +
> + if (iph->version == 4) {
> + /* special-case 6in4 tunnelling, as that is a common way to get
> + * v6 connectivity in the home
> + */
> + if (iph->protocol == IPPROTO_IPV6) {
> + if (!pskb_may_pull(skb, (skb_network_offset(skb) +
> + ip_hdrlen(skb) +
> + sizeof(struct ipv6hdr))))
> + return NULL;
> +
> + ipv6h = (struct ipv6hdr *)(skb_network_header(skb) +
> + ip_hdrlen(skb));
> +
> + if (ipv6h->nexthdr != IPPROTO_TCP)
> + return NULL;
> +
> + skb_set_inner_network_header(skb,
> + skb_network_offset(skb) +
> + ip_hdrlen(skb));
> + skb_set_inner_transport_header(skb,
> + skb_inner_network_offset(skb) +
> + sizeof(struct ipv6hdr));
This is not allowed for a dissector.
