net: sched: remove TC_MUNGED bits

Not used.

pedit sets TC_MUNGED when packet content was altered, but all the core
does is unset MUNGED again and then set OK2MUNGE.

And the latter isn't tested anywhere. So lets remove both
TC_MUNGED and TC_OK2MUNGE.
Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/tc-actions-env-rules.txt

@@ -14,8 +14,6 @@ resets them for you, so invoke skb_act_clone() rather than skb_clone().
 
 2) If you munge any packet thou shalt call pskb_expand_head in the case
 someone else is referencing the skb. After that you "own" the skb.
-You must also tell us if it is ok to munge the packet (TC_OK2MUNGE),
-this way any action downstream can stomp on the packet.
 
 3) Dropping packets you don't own is a no-no. You simply return
 TC_ACT_SHOT to the caller and they will drop it.

include/net/sch_generic.h

@@ -755,8 +755,6 @@ static inline struct sk_buff *skb_act_clone(struct sk_buff *skb, gfp_t gfp_mask,
 
 	if (n) {
 		n->tc_verd = SET_TC_VERD(n->tc_verd, 0);
-		n->tc_verd = CLR_TC_OK2MUNGE(n->tc_verd);
-		n->tc_verd = CLR_TC_MUNGED(n->tc_verd);
 	}
 	return n;
 }

include/uapi/linux/pkt_cls.h

@@ -35,6 +35,8 @@ bits 9,10,11: redirect counter -  redirect TTL. Loop avoidance
  *
  * */
 
+#ifndef __KERNEL__
+/* backwards compat for userspace only */
 #define TC_MUNGED          _TC_MAKEMASK1(0)
 #define SET_TC_MUNGED(v)   ( TC_MUNGED | (v & ~TC_MUNGED))
 #define CLR_TC_MUNGED(v)   ( v & ~TC_MUNGED)
@@ -42,6 +44,7 @@ bits 9,10,11: redirect counter -  redirect TTL. Loop avoidance
 #define TC_OK2MUNGE        _TC_MAKEMASK1(1)
 #define SET_TC_OK2MUNGE(v)   ( TC_OK2MUNGE | (v & ~TC_OK2MUNGE))
 #define CLR_TC_OK2MUNGE(v)   ( v & ~TC_OK2MUNGE)
+#endif
 
 #define S_TC_VERD          _TC_MAKE32(2)
 #define M_TC_VERD          _TC_MAKEMASK(4,S_TC_VERD)

net/sched/act_api.c

@@ -392,11 +392,6 @@ int tcf_action_exec(struct sk_buff *skb, const struct list_head *actions,
 	list_for_each_entry(a, actions, list) {
 repeat:
 		ret = a->ops->act(skb, a, res);
-		if (TC_MUNGED & skb->tc_verd) {
-			/* copied already, allow trampling */
-			skb->tc_verd = SET_TC_OK2MUNGE(skb->tc_verd);
-			skb->tc_verd = CLR_TC_MUNGED(skb->tc_verd);
-		}
 		if (ret == TC_ACT_REPEAT)
 			goto repeat;	/* we need a ttl - JHS */
 		if (ret != TC_ACT_PIPE)

net/sched/act_pedit.c

@@ -108,7 +108,7 @@ static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
 		     struct tcf_result *res)
 {
 	struct tcf_pedit *p = a->priv;
-	int i, munged = 0;
+	int i;
 	unsigned int off;
 
 	if (skb_unclone(skb, GFP_ATOMIC))
@@ -156,11 +156,8 @@ static int tcf_pedit(struct sk_buff *skb, const struct tc_action *a,
 			*ptr = ((*ptr & tkey->mask) ^ tkey->val);
 			if (ptr == &_data)
 				skb_store_bits(skb, off + offset, ptr, 4);
-			munged++;
 		}
 
-		if (munged)
-			skb->tc_verd = SET_TC_MUNGED(skb->tc_verd);
 		goto done;
 	} else
 		WARN(1, "pedit BUG: index %d\n", p->tcf_index);