netdev - Re: [PATCH net-next v2 1/2] net: l3mdev: Add hook in ip and ipv6

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Date:	Sat, 7 May 2016 08:50:49 -0600
From:	David Ahern <dsa@...ulusnetworks.com>
To:	Shmulik Ladkani <shmulik.ladkani@...il.com>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH net-next v2 1/2] net: l3mdev: Add hook in ip and ipv6

On 5/7/16 2:30 AM, Shmulik Ladkani wrote:
> Hi David,
>
> On Fri,  6 May 2016 18:49:40 -0700 David Ahern <dsa@...ulusnetworks.com> wrote:
>> +static bool ipv6_ndisc_frame(const struct sk_buff *skb)
>> +{
>> +	const struct ipv6hdr *ipv6h = (struct ipv6hdr *)skb->data;
>> +	size_t hlen = sizeof(*ipv6h);
>> +	bool rc = false;
>> +
>> +	if (ipv6h->nexthdr == NEXTHDR_ICMP) {
>> +		const struct icmp6hdr *icmph;
>> +
>> +		if (skb->len < hlen + sizeof(*icmph))
>> +			goto out;
>> +
>> +		icmph = (struct icmp6hdr *)(skb->data + sizeof(*ipv6h));
>> +		switch (icmph->icmp6_type) {
>
> Don't we need an additional pskb_may_pull here?
>
> If I get it right, 'ipv6_rcv' only assures sizeof(ipv6hdr) to be in the
> linear header (unless it's a NEXTHDR_HOP, which is not the case here).

yes, I inadvertently dropped this:

commit 65c38aa653c14df49e19faad74bd375f36e61c57
Author: David Ahern <dsa@...ulusnetworks.com>
Date:   Tue Feb 23 10:10:26 2016 -0800

     net: vrf: Remove direct access to skb->data

when I forward ported this patch. Will fix and re-send.

>
>> +static inline
>> +struct sk_buff *l3mdev_l3_rcv(struct sk_buff *skb, u16 proto)
>> +{
>> +	struct net_device *master = NULL;
>> +
>> +	if (netif_is_l3_slave(skb->dev))
>> +		master = netdev_master_upper_dev_get_rcu(skb->dev);
>> +
>> +	else if (netif_is_l3_master(skb->dev))
>> +		master = skb->dev;
>> +
>> +	if (master && master->l3mdev_ops->l3mdev_l3_rcv)
>> +		skb = master->l3mdev_ops->l3mdev_l3_rcv(master, skb, proto);
>
> In the case where netif_is_l3_master(skb->dev) is true, can you explain
> why we need to pass it through the l3mdev_l3_rcv callback again?

what do you mean again? This is only time the l3mdev_l3_rcv method is 
called on a packet.