[SRU][F:linux-bluefield][PATCH V1 1/8] net/sched: act_ct: fix restore the qdisc_skb_cb after defrag

[Tim Gardner]

Are you sure this is the right backport ? I think you'll orphan skb's in 
the error case in tcf_ct_handle_fragments(). Attached is the backport I 
came up with, though not compiled and not tested.

rtg

On 8/26/21 4:43 PM, Bodong Wang wrote:
> From: wenxu <wenxu at ucloud.cn>
> 
> BugLink: https://bugs.launchpad.net/bugs/1940872
> 
> The fragment packets do defrag in tcf_ct_handle_fragments
> will clear the skb->cb which make the qdisc_skb_cb clear
> too. So the qdsic_skb_cb should be store before defrag and
> restore after that.
> It also update the pkt_len after all the
> fragments finish the defrag to one packet and make the
> following actions counter correct.
> 
> Fixes: b57dc7c13ea9 ("net/sched: Introduce action ct")
> Signed-off-by: wenxu <wenxu at ucloud.cn>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (backported from ae372cb1750f6c95370f92fe5f5620e0954663ba)
> [bodong: adapt variables with older kernel ]
> Signed-off-by: Bodong Wang <bodong at nvidia.com>
> ---
>   net/sched/act_ct.c | 16 ++++++++++++++--
>   1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
> index c3fd092..39547cf1 100644
> --- a/net/sched/act_ct.c
> +++ b/net/sched/act_ct.c
> @@ -680,9 +680,10 @@ static int tcf_ct_ipv6_is_fragment(struct sk_buff *skb, bool *frag)
>   }
>   
>   static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
> -				   u8 family, u16 zone)
> +				   u8 family, u16 zone, bool *defrag)
>   {
>   	enum ip_conntrack_info ctinfo;
> +	struct qdisc_skb_cb cb;
>   	struct nf_conn *ct;
>   	int err = 0;
>   	bool frag;
> @@ -700,6 +701,7 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
>   		return err;
>   
>   	skb_get(skb);
> +	cb = *qdisc_skb_cb(skb);
>   
>   	if (family == NFPROTO_IPV4) {
>   		enum ip_defrag_users user = IP_DEFRAG_CONNTRACK_IN + zone;
> @@ -710,6 +712,9 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
>   		local_bh_enable();
>   		if (err && err != -EINPROGRESS)
>   			return err;
> +
> +		if (!err)
> +			*defrag = true;
>   	} else { /* NFPROTO_IPV6 */
>   #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
>   		enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
> @@ -718,12 +723,16 @@ static int tcf_ct_handle_fragments(struct net *net, struct sk_buff *skb,
>   		err = nf_ct_frag6_gather(net, skb, user);
>   		if (err && err != -EINPROGRESS)
>   			return err;
> +
> +		if (!err)
> +			*defrag = true;
>   #else
>   		err = -EOPNOTSUPP;
>   		goto out_free;
>   #endif
>   	}
>   
> +	*qdisc_skb_cb(skb) = cb;
>   	skb_clear_hash(skb);
>   	skb->ignore_df = 1;
>   	return err;
> @@ -926,6 +935,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
>   	int nh_ofs, err, retval;
>   	struct tcf_ct_params *p;
>   	bool skip_add = false;
> +	bool defrag = false;
>   	struct nf_conn *ct;
>   	u8 family;
>   
> @@ -957,7 +967,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
>   	 */
>   	nh_ofs = skb_network_offset(skb);
>   	skb_pull_rcsum(skb, nh_ofs);
> -	err = tcf_ct_handle_fragments(net, skb, family, p->zone);
> +	err = tcf_ct_handle_fragments(net, skb, family, p->zone, &defrag);
>   	if (err == -EINPROGRESS) {
>   		retval = TC_ACT_STOLEN;
>   		goto out;
> @@ -1029,6 +1039,8 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
>   	qdisc_skb_cb(skb)->post_ct = true;
>   out_clear:
>   	tcf_action_update_bstats(&c->common, skb);
> +	if (defrag)
> +		qdisc_skb_cb(skb)->pkt_len = skb->len;
>   	return retval;
>   
>   drop:
> 

-- 
-----------
Tim Gardner
Canonical, Inc
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