Re: [PATCH v2 ipsec-next 1/2] xfrm: introduce forwarding of ICMP Error messages

Steffen Klassert
2023-11-17T09:13:19Z

On Fri, Oct 27, 2023 at 10:16:29AM +0200, Antony Antony wrote:
> +
> +static struct sk_buff *xfrm_icmp_flow_decode(struct sk_buff *skb,
> + unsigned short family,
> + struct flowi *fl,
> + struct flowi *fl1)
> +{
> + struct net *net = dev_net(skb->dev);
> + struct sk_buff *newskb = skb_clone(skb, GFP_ATOMIC);
> + int hl = family == AF_INET ? (sizeof(struct iphdr) + sizeof(struct icmphdr)) :
> + (sizeof(struct ipv6hdr) + sizeof(struct icmp6hdr));
> + skb_reset_network_header(newskb);

This is not needed there.

> +
> + if (!pskb_pull(newskb, hl))
> + return NULL;

This leaks newskb.

> + skb_reset_network_header(newskb);
> +
> + if (xfrm_decode_session_reverse(net, newskb, fl1, family) < 0) {
> + kfree_skb(newskb);

The newskb is not dropped because of an error, maybe better use
consume_skb().

> + XFRM_INC_STATS(net, LINUX_MIB_XFRMINHDRERROR);

This might bump a second stat counter for this packet. Also
this is not really an error, because you just can't parse
the payload of the icmp packet.

> + return NULL;
> + }
> +
> + fl1->flowi_oif = fl->flowi_oif;
> + fl1->flowi_mark = fl->flowi_mark;
> + fl1->flowi_tos = fl->flowi_tos;
> + nf_nat_decode_session(newskb, fl1, family);
> +
> + return newskb;

Why do you return newskb here? It is not used in all
of the calling functions.

The rest looks good, thanks!