net/sched: act_vlan: Introduce TCA_VLAN_ACT_MODIFY vlan action

TCA_VLAN_ACT_MODIFY allows one to change an existing tag.

It accepts same attributes as TCA_VLAN_ACT_PUSH (protocol, id,
priority).
If packet is vlan tagged, then the tag gets overwritten according to
user specified attributes.

For example, this allows user to replace a tag's vid while preserving
its priority bits (as opposed to "action vlan pop pipe action vlan push").

Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 1 deletions

diff --git a/net/sched/act_vlan.c b/net/sched/act_vlan.c
index 59a8d3150ae2..a95c00b119da 100644
--- a/net/sched/act_vlan.c
+++ b/net/sched/act_vlan.c
@@ -30,6 +30,7 @@ static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a,
         struct tcf_vlan *v = to_vlan(a);
         int action;
         int err;
+        u16 tci;
 
         spin_lock(&v->tcf_lock);
         tcf_lastuse_update(&v->tcf_tm);
@@ -48,6 +49,30 @@ static int tcf_vlan(struct sk_buff *skb, const struct tc_action *a,
                 if (err)
                         goto drop;
                 break;
+        case TCA_VLAN_ACT_MODIFY:
+                /* No-op if no vlan tag (either hw-accel or in-payload) */
+                if (!skb_vlan_tagged(skb))
+                        goto unlock;
+                /* extract existing tag (and guarantee no hw-accel tag) */
+                if (skb_vlan_tag_present(skb)) {
+                        tci = skb_vlan_tag_get(skb);
+                        skb->vlan_tci = 0;
+                } else {
+                        /* in-payload vlan tag, pop it */
+                        err = __skb_vlan_pop(skb, &tci);
+                        if (err)
+                                goto drop;
+                }
+                /* replace the vid */
+                tci = (tci & ~VLAN_VID_MASK) | v->tcfv_push_vid;
+                /* replace prio bits, if tcfv_push_prio specified */
+                if (v->tcfv_push_prio) {
+                        tci &= ~VLAN_PRIO_MASK;
+                        tci |= v->tcfv_push_prio << VLAN_PRIO_SHIFT;
+                }
+                /* put updated tci as hwaccel tag */
+                __vlan_hwaccel_put_tag(skb, v->tcfv_push_proto, tci);
+                break;
         default:
                 BUG();
         }
@@ -102,6 +127,7 @@ static int tcf_vlan_init(struct net *net, struct nlattr *nla,
         case TCA_VLAN_ACT_POP:
                 break;
         case TCA_VLAN_ACT_PUSH:
+        case TCA_VLAN_ACT_MODIFY:
                 if (!tb[TCA_VLAN_PUSH_VLAN_ID]) {
                         if (exists)
                                 tcf_hash_release(*a, bind);
@@ -185,7 +211,8 @@ static int tcf_vlan_dump(struct sk_buff *skb, struct tc_action *a,
         if (nla_put(skb, TCA_VLAN_PARMS, sizeof(opt), &opt))
                 goto nla_put_failure;
 
-        if (v->tcfv_action == TCA_VLAN_ACT_PUSH &&
+        if ((v->tcfv_action == TCA_VLAN_ACT_PUSH ||
+             v->tcfv_action == TCA_VLAN_ACT_MODIFY) &&
             (nla_put_u16(skb, TCA_VLAN_PUSH_VLAN_ID, v->tcfv_push_vid) ||
              nla_put_be16(skb, TCA_VLAN_PUSH_VLAN_PROTOCOL,
                           v->tcfv_push_proto) ||