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

Antony Antony
2023-11-25T22:48:35Z

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.