netfilter: nf_tables: map basechain priority to hardware priority

This patch adds initial support for offloading basechains using the
priority range from 1 to 65535. This is restricting the netfilter
priority range to 16-bit integer since this is what most drivers assume
so far from tc. It should be possible to extend this range of supported
priorities later on once drivers are updated to support for 32-bit
integer priorities.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_tables_offload.h

@@ -73,4 +73,6 @@ int nft_flow_rule_offload_commit(struct net *net);
 	(__reg)->key		= __key;				\
 	memset(&(__reg)->mask, 0xff, (__reg)->len);
 
+int nft_chain_offload_priority(struct nft_base_chain *basechain);
+
 #endif

net/netfilter/nf_tables_api.c

@@ -1667,6 +1667,10 @@ static int nf_tables_addchain(struct nft_ctx *ctx, u8 family, u8 genmask,
 
 		chain->flags |= NFT_BASE_CHAIN | flags;
 		basechain->policy = NF_ACCEPT;
+		if (chain->flags & NFT_CHAIN_HW_OFFLOAD &&
+		    nft_chain_offload_priority(basechain) < 0)
+			return -EOPNOTSUPP;
+
 		flow_block_init(&basechain->flow_block);
 	} else {
 		chain = kzalloc(sizeof(*chain), GFP_KERNEL);

net/netfilter/nf_tables_offload.c

@@ -103,10 +103,11 @@ void nft_offload_update_dependency(struct nft_offload_ctx *ctx,
 }
 
 static void nft_flow_offload_common_init(struct flow_cls_common_offload *common,
-					 __be16 proto,
-					struct netlink_ext_ack *extack)
+					 __be16 proto, int priority,
+					 struct netlink_ext_ack *extack)
 {
 	common->protocol = proto;
+	common->prio = priority;
 	common->extack = extack;
 }
 
@@ -124,6 +125,15 @@ static int nft_setup_cb_call(struct nft_base_chain *basechain,
 	return 0;
 }
 
+int nft_chain_offload_priority(struct nft_base_chain *basechain)
+{
+	if (basechain->ops.priority <= 0 ||
+	    basechain->ops.priority > USHRT_MAX)
+		return -1;
+
+	return 0;
+}
+
 static int nft_flow_offload_rule(struct nft_trans *trans,
 				 enum flow_cls_command command)
 {
@@ -142,7 +152,8 @@ static int nft_flow_offload_rule(struct nft_trans *trans,
 	if (flow)
 		proto = flow->proto;
 
-	nft_flow_offload_common_init(&cls_flow.common, proto, &extack);
+	nft_flow_offload_common_init(&cls_flow.common, proto,
+				     basechain->ops.priority, &extack);
 	cls_flow.command = command;
 	cls_flow.cookie = (unsigned long) rule;
 	if (flow)