[PATCH net v2] net/sched: act_ct: fix restore the qdisc_skb_cb after defrag

[wenxu]

From: wenxu <we...@ucloud.cn>

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 <we...@ucloud.cn>
---
v2: update qdisc_skb_cb(skb)->pkt_len only for reassembled skbs

 net/sched/act_ct.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 67504ae..42bc231 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -673,13 +673,15 @@ 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;
 
+       *defrag = false;
        /* Previously seen (loopback)? Ignore. */
        ct = nf_ct_get(skb, &ctinfo);
        if ((ct && !nf_ct_is_template(ct)) || ctinfo == IP_CT_UNTRACKED)
@@ -693,6 +695,7 @@ 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;
@@ -703,6 +706,8 @@ static int tcf_ct_handle_fragments(struct net *net, struct 
sk_buff *skb,
                local_bh_enable();
                if (err && err != -EINPROGRESS)
                        goto out_free;
+               if (!err)
+                       *defrag = true;
        } else { /* NFPROTO_IPV6 */
 #if IS_ENABLED(CONFIG_NF_DEFRAG_IPV6)
                enum ip6_defrag_users user = IP6_DEFRAG_CONNTRACK_IN + zone;
@@ -711,12 +716,15 @@ 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)
                        goto out_free;
+               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;
@@ -915,6 +923,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct 
tc_action *a,
        struct tcf_ct_params *p;
        bool skip_add = false;
        struct nf_conn *ct;
+       bool defrag;
        u8 family;
 
        p = rcu_dereference_bh(c->params);
@@ -946,7 +955,7 @@ 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;
@@ -1014,6 +1023,8 @@ static int tcf_ct_act(struct sk_buff *skb, const struct 
tc_action *a,
 
 out:
        tcf_action_update_bstats(&c->common, skb);
+       if (defrag)
+               qdisc_skb_cb(skb)->pkt_len = skb->len;
        return retval;
 
 drop:
-- 
1.8.3.1