[PATCH nf-next] netfilter: nfnetlink_queue: prefer skb_mac_header helpers

[Florian Westphal <fw@strlen.de>]

This adds implicit DEBUG_WARN_ON_ONCE for debug configurations.
No other changes intended.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nfnetlink_queue.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
index 5379d8ff39c0..c2906706c82a 100644
--- a/net/netfilter/nfnetlink_queue.c
+++ b/net/netfilter/nfnetlink_queue.c
@@ -602,6 +602,7 @@ static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)
 {
 	struct sk_buff *entskb = entry->skb;
 	u32 nlalen = 0;
+	u32 mac_len;
 
 	if (entry->state.pf != PF_BRIDGE || !skb_mac_header_was_set(entskb))
 		return 0;
@@ -610,9 +611,9 @@ static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)
 		nlalen += nla_total_size(nla_total_size(sizeof(__be16)) +
 					 nla_total_size(sizeof(__be16)));
 
-	if (entskb->network_header > entskb->mac_header)
-		nlalen += nla_total_size((entskb->network_header -
-					  entskb->mac_header));
+	mac_len = skb_mac_header_len(entskb);
+	if (mac_len > 0)
+		nlalen += nla_total_size(mac_len);
 
 	return nlalen;
 }
@@ -620,6 +621,7 @@ static u32 nfqnl_get_bridge_size(struct nf_queue_entry *entry)
 static int nfqnl_put_bridge(struct nf_queue_entry *entry, struct sk_buff *skb)
 {
 	struct sk_buff *entskb = entry->skb;
+	u32 mac_len;
 
 	if (entry->state.pf != PF_BRIDGE || !skb_mac_header_was_set(entskb))
 		return 0;
@@ -638,12 +640,10 @@ static int nfqnl_put_bridge(struct nf_queue_entry *entry, struct sk_buff *skb)
 		nla_nest_end(skb, nest);
 	}
 
-	if (entskb->mac_header < entskb->network_header) {
-		int len = (int)(entskb->network_header - entskb->mac_header);
-
-		if (nla_put(skb, NFQA_L2HDR, len, skb_mac_header(entskb)))
-			goto nla_put_failure;
-	}
+	mac_len = skb_mac_header_len(entskb);
+	if (mac_len > 0 &&
+	    nla_put(skb, NFQA_L2HDR, mac_len, skb_mac_header(entskb)))
+		goto nla_put_failure;
 
 	return 0;
 
@@ -1027,13 +1027,13 @@ nf_queue_entry_dup(struct nf_queue_entry *e)
 static void nf_bridge_adjust_skb_data(struct sk_buff *skb)
 {
 	if (nf_bridge_info_get(skb))
-		__skb_push(skb, skb->network_header - skb->mac_header);
+		__skb_push(skb, skb_mac_header_len(skb));
 }
 
 static void nf_bridge_adjust_segmented_data(struct sk_buff *skb)
 {
 	if (nf_bridge_info_get(skb))
-		__skb_pull(skb, skb->network_header - skb->mac_header);
+		__skb_pull(skb, skb_mac_header_len(skb));
 }
 #else
 #define nf_bridge_adjust_skb_data(s) do {} while (0)
@@ -1492,8 +1492,7 @@ static int nfqa_parse_bridge(struct nf_queue_entry *entry,
 	}
 
 	if (nfqa[NFQA_L2HDR]) {
-		int mac_header_len = entry->skb->network_header -
-			entry->skb->mac_header;
+		u32 mac_header_len = skb_mac_header_len(entry->skb);
 
 		if (mac_header_len != nla_len(nfqa[NFQA_L2HDR]))
 			return -EINVAL;
-- 
2.52.0