[PATCH net,v5 2/2] netfilter: nf_tables: map basechain priority to hardware priority

[Pablo Neira Ayuso <pablo@netfilter.org>]

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>
---
v5: fix clang warning by simplifying the mapping of hardware priorities
    to basechain priority in the range of 1-65535. Zero is left behind
    since some drivers do not support this, no negative basechain
    priorities are used at this stage.

 include/net/netfilter/nf_tables_offload.h |  2 ++
 net/netfilter/nf_tables_api.c             |  4 ++++
 net/netfilter/nf_tables_offload.c         | 17 ++++++++++++++---
 3 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/include/net/netfilter/nf_tables_offload.h b/include/net/netfilter/nf_tables_offload.h
index 3196663a10e3..c8b9dec376f5 100644
--- a/include/net/netfilter/nf_tables_offload.h
+++ b/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
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 605a7cfe7ca7..b65caf4974e1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1662,6 +1662,10 @@ 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);
diff --git a/net/netfilter/nf_tables_offload.c b/net/netfilter/nf_tables_offload.c
index 64f5fd5f240e..c0d18c1d77ac 100644
--- a/net/netfilter/nf_tables_offload.c
+++ b/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)
-- 
2.11.0