[PATCH net v3 3/3] net/sched: act_skbedit: fix 'inheritdsfield' in case of QinQ packet

[Davide Caratti <dcaratti@redhat.com>]

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 <shuali@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
---
 net/sched/act_skbedit.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 7ec159b95364..34a0c661c8c5 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))
@@ -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