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

[Antony Antony <antony@phenome.org>]

On Fri, Nov 17, 2023 at 10:13:15AM +0100, Steffen Klassert via Devel wrote:
> 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.

fixed.
> 
> > +
> > +	if (!pskb_pull(newskb, hl))
> > +		return NULL;
> 
> This leaks newskb.

fixedd

> 
> > +	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().

good idea. I will change to 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. 

yes fixed

> 
> > +		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 Acalling functions.

I thought fl1,  decode session, had pointers to skb fl1. That is not the 
case. Now the skb is consumed and not returned.


> The rest looks good, thanks!

thanks for the review. I will send out new version soon.