[PATCH net v2 3/3] net/sched: act_skbedit: fix 'inheritdsfield' in case of QinQ packet

[Davide Caratti]

like it was previously done on TC 'csum' (see commit 2ecba2d1e45b ("net:
sched: act_csum: Fix csum calc for tagged packets")), TC 'skbedit' might
need to adjust the network offset, if the packet has unstripped/multiple
tags: otherwise 'inheritdsfield' will just be skipped for QinQ packets.

Fixes: e7e3728bd776 ("net:sched: add action inheritdsfield to skbedit")
CC: Li Shuang <shu...@redhat.com>
Signed-off-by: Davide Caratti <dcara...@redhat.com>
---
 net/sched/act_skbedit.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 7ec159b95364..693a4317de6e 100644
--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -39,6 +39,7 @@ static int tcf_skbedit_act(struct sk_buff *skb, const struct 
tc_action *a,
 {
        struct tcf_skbedit *d = to_skbedit(a);
        struct tcf_skbedit_params *params;
+       unsigned int vlan_hdr_count = 0;
        int action;
 
        tcf_lastuse_update(&d->tcf_tm);
@@ -50,9 +51,17 @@ static int tcf_skbedit_act(struct sk_buff *skb, const struct 
tc_action *a,
        if (params->flags & SKBEDIT_F_PRIORITY)
                skb->priority = params->priority;
        if (params->flags & SKBEDIT_F_INHERITDSFIELD) {
-               int wlen = skb_network_offset(skb);
-
-               switch (tc_skb_protocol(skb)) {
+               __be16 proto = tc_skb_protocol(skb);
+               int wlen;
+
+again:
+               wlen = skb_network_offset(skb);
+               switch (proto) {
+               case htons(ETH_P_8021AD): /* Fall Through */
+               case htons(ETH_P_8021Q):
+                       if (tc_skb_pull_vlans(skb, &vlan_hdr_count, &proto))
+                               goto err;
+                       goto again;
                case htons(ETH_P_IP):
                        wlen += sizeof(struct iphdr);
                        if (!pskb_may_pull(skb, wlen))
@@ -61,7 +70,7 @@ static int tcf_skbedit_act(struct sk_buff *skb, const struct 
tc_action *a,
                        break;
 
                case htons(ETH_P_IPV6):
-                       wlen += sizeof(struct ipv6hdr);
+                       wlen +=  sizeof(struct ipv6hdr);
                        if (!pskb_may_pull(skb, wlen))
                                goto err;
                        skb->priority = ipv6_get_dsfield(ipv6_hdr(skb)) >> 2;
@@ -77,11 +86,18 @@ static int tcf_skbedit_act(struct sk_buff *skb, const 
struct tc_action *a,
        }
        if (params->flags & SKBEDIT_F_PTYPE)
                skb->pkt_type = params->ptype;
+
+out:
+       while (vlan_hdr_count--) {
+               skb_push(skb, VLAN_HLEN);
+               skb_reset_network_header(skb);
+       }
        return action;
 
 err:
        qstats_drop_inc(this_cpu_ptr(d->common.cpu_qstats));
-       return TC_ACT_SHOT;
+       action = TC_ACT_SHOT;
+       goto out;
 }
 
 static const struct nla_policy skbedit_policy[TCA_SKBEDIT_MAX + 1] = {
-- 
2.20.1