netfilter: flowtable: use atomic bitwise operations for flow flags

Originally, all flow flag bits were set on only from the workqueue. With
the introduction of the flow teardown state and hardware offload this is
no longer true. Let's be safe and use atomic bitwise operation to
operation with flow flags.

Fixes: 59c466dd ("netfilter: nf_flow_table: add a new flow state for tearing down offloading")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

include/net/netfilter/nf_flow_table.h

@@ -83,12 +83,14 @@ struct flow_offload_tuple_rhash {
 	struct flow_offload_tuple	tuple;
 };
 
-#define FLOW_OFFLOAD_SNAT	0x1
-#define FLOW_OFFLOAD_DNAT	0x2
-#define FLOW_OFFLOAD_TEARDOWN	0x8
-#define FLOW_OFFLOAD_HW		0x10
-#define FLOW_OFFLOAD_HW_DYING	0x20
-#define FLOW_OFFLOAD_HW_DEAD	0x40
+enum nf_flow_flags {
+	NF_FLOW_SNAT,
+	NF_FLOW_DNAT,
+	NF_FLOW_TEARDOWN,
+	NF_FLOW_HW,
+	NF_FLOW_HW_DYING,
+	NF_FLOW_HW_DEAD,
+};
 
 enum flow_offload_type {
 	NF_FLOW_OFFLOAD_UNSPEC	= 0,
@@ -98,7 +100,7 @@ enum flow_offload_type {
 struct flow_offload {
 	struct flow_offload_tuple_rhash		tuplehash[FLOW_OFFLOAD_DIR_MAX];
 	struct nf_conn				*ct;
-	u16					flags;
+	unsigned long				flags;
 	u16					type;
 	u32					timeout;
 	struct rcu_head				rcu_head;

net/netfilter/nf_flow_table_core.c

@@ -61,9 +61,9 @@ struct flow_offload *flow_offload_alloc(struct nf_conn *ct)
 	flow_offload_fill_dir(flow, FLOW_OFFLOAD_DIR_REPLY);
 
 	if (ct->status & IPS_SRC_NAT)
-		flow->flags |= FLOW_OFFLOAD_SNAT;
+		__set_bit(NF_FLOW_SNAT, &flow->flags);
 	if (ct->status & IPS_DST_NAT)
-		flow->flags |= FLOW_OFFLOAD_DNAT;
+		__set_bit(NF_FLOW_DNAT, &flow->flags);
 
 	return flow;
 
@@ -269,7 +269,7 @@ static void flow_offload_del(struct nf_flowtable *flow_table,
 
 	if (nf_flow_has_expired(flow))
 		flow_offload_fixup_ct(flow->ct);
-	else if (flow->flags & FLOW_OFFLOAD_TEARDOWN)
+	else if (test_bit(NF_FLOW_TEARDOWN, &flow->flags))
 		flow_offload_fixup_ct_timeout(flow->ct);
 
 	flow_offload_free(flow);
@@ -277,7 +277,7 @@ static void flow_offload_del(struct nf_flowtable *flow_table,
 
 void flow_offload_teardown(struct flow_offload *flow)
 {
-	flow->flags |= FLOW_OFFLOAD_TEARDOWN;
+	set_bit(NF_FLOW_TEARDOWN, &flow->flags);
 
 	flow_offload_fixup_ct_state(flow->ct);
 }
@@ -298,7 +298,7 @@ flow_offload_lookup(struct nf_flowtable *flow_table,
 
 	dir = tuplehash->tuple.dir;
 	flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
-	if (flow->flags & FLOW_OFFLOAD_TEARDOWN)
+	if (test_bit(NF_FLOW_TEARDOWN, &flow->flags))
 		return NULL;
 
 	if (unlikely(nf_ct_is_dying(flow->ct)))
@@ -347,16 +347,16 @@ static void nf_flow_offload_gc_step(struct flow_offload *flow, void *data)
 	struct nf_flowtable *flow_table = data;
 
 	if (nf_flow_has_expired(flow) || nf_ct_is_dying(flow->ct) ||
-	    (flow->flags & FLOW_OFFLOAD_TEARDOWN)) {
-		if (flow->flags & FLOW_OFFLOAD_HW) {
-			if (!(flow->flags & FLOW_OFFLOAD_HW_DYING))
+	    test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
+		if (test_bit(NF_FLOW_HW, &flow->flags)) {
+			if (!test_bit(NF_FLOW_HW_DYING, &flow->flags))
 				nf_flow_offload_del(flow_table, flow);
-			else if (flow->flags & FLOW_OFFLOAD_HW_DEAD)
+			else if (test_bit(NF_FLOW_HW_DEAD, &flow->flags))
 				flow_offload_del(flow_table, flow);
 		} else {
 			flow_offload_del(flow_table, flow);
 		}
-	} else if (flow->flags & FLOW_OFFLOAD_HW) {
+	} else if (test_bit(NF_FLOW_HW, &flow->flags)) {
 		nf_flow_offload_stats(flow_table, flow);
 	}
 }

net/netfilter/nf_flow_table_ip.c

@@ -144,11 +144,11 @@ static int nf_flow_nat_ip(const struct flow_offload *flow, struct sk_buff *skb,
 {
 	struct iphdr *iph = ip_hdr(skb);
 
-	if (flow->flags & FLOW_OFFLOAD_SNAT &&
+	if (test_bit(NF_FLOW_SNAT, &flow->flags) &&
 	    (nf_flow_snat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
 	     nf_flow_snat_ip(flow, skb, iph, thoff, dir) < 0))
 		return -1;
-	if (flow->flags & FLOW_OFFLOAD_DNAT &&
+	if (test_bit(NF_FLOW_DNAT, &flow->flags) &&
 	    (nf_flow_dnat_port(flow, skb, thoff, iph->protocol, dir) < 0 ||
 	     nf_flow_dnat_ip(flow, skb, iph, thoff, dir) < 0))
 		return -1;
@@ -414,11 +414,11 @@ static int nf_flow_nat_ipv6(const struct flow_offload *flow,
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
 	unsigned int thoff = sizeof(*ip6h);
 
-	if (flow->flags & FLOW_OFFLOAD_SNAT &&
+	if (test_bit(NF_FLOW_SNAT, &flow->flags) &&
 	    (nf_flow_snat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
 	     nf_flow_snat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
 		return -1;
-	if (flow->flags & FLOW_OFFLOAD_DNAT &&
+	if (test_bit(NF_FLOW_DNAT, &flow->flags) &&
 	    (nf_flow_dnat_port(flow, skb, thoff, ip6h->nexthdr, dir) < 0 ||
 	     nf_flow_dnat_ipv6(flow, skb, ip6h, thoff, dir) < 0))
 		return -1;

net/netfilter/nf_flow_table_offload.c

@@ -450,16 +450,16 @@ int nf_flow_rule_route_ipv4(struct net *net, const struct flow_offload *flow,
 	    flow_offload_eth_dst(net, flow, dir, flow_rule) < 0)
 		return -1;
 
-	if (flow->flags & FLOW_OFFLOAD_SNAT) {
+	if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 		flow_offload_ipv4_snat(net, flow, dir, flow_rule);
 		flow_offload_port_snat(net, flow, dir, flow_rule);
 	}
-	if (flow->flags & FLOW_OFFLOAD_DNAT) {
+	if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 		flow_offload_ipv4_dnat(net, flow, dir, flow_rule);
 		flow_offload_port_dnat(net, flow, dir, flow_rule);
 	}
-	if (flow->flags & FLOW_OFFLOAD_SNAT ||
-	    flow->flags & FLOW_OFFLOAD_DNAT)
+	if (test_bit(NF_FLOW_SNAT, &flow->flags) ||
+	    test_bit(NF_FLOW_DNAT, &flow->flags))
 		flow_offload_ipv4_checksum(net, flow, flow_rule);
 
 	flow_offload_redirect(flow, dir, flow_rule);
@@ -476,11 +476,11 @@ int nf_flow_rule_route_ipv6(struct net *net, const struct flow_offload *flow,
 	    flow_offload_eth_dst(net, flow, dir, flow_rule) < 0)
 		return -1;
 
-	if (flow->flags & FLOW_OFFLOAD_SNAT) {
+	if (test_bit(NF_FLOW_SNAT, &flow->flags)) {
 		flow_offload_ipv6_snat(net, flow, dir, flow_rule);
 		flow_offload_port_snat(net, flow, dir, flow_rule);
 	}
-	if (flow->flags & FLOW_OFFLOAD_DNAT) {
+	if (test_bit(NF_FLOW_DNAT, &flow->flags)) {
 		flow_offload_ipv6_dnat(net, flow, dir, flow_rule);
 		flow_offload_port_dnat(net, flow, dir, flow_rule);
 	}
@@ -636,7 +636,7 @@ static void flow_offload_tuple_del(struct flow_offload_work *offload,
 	list_for_each_entry(block_cb, &flowtable->flow_block.cb_list, list)
 		block_cb->cb(TC_SETUP_CLSFLOWER, &cls_flow, block_cb->cb_priv);
 
-	offload->flow->flags |= FLOW_OFFLOAD_HW_DEAD;
+	set_bit(NF_FLOW_HW_DEAD, &offload->flow->flags);
 }
 
 static int flow_offload_rule_add(struct flow_offload_work *offload,
@@ -723,7 +723,7 @@ static void flow_offload_work_handler(struct work_struct *work)
 		case FLOW_CLS_REPLACE:
 			ret = flow_offload_work_add(offload);
 			if (ret < 0)
-				offload->flow->flags &= ~FLOW_OFFLOAD_HW;
+				__clear_bit(NF_FLOW_HW, &offload->flow->flags);
 			break;
 		case FLOW_CLS_DESTROY:
 			flow_offload_work_del(offload);
@@ -776,7 +776,7 @@ void nf_flow_offload_add(struct nf_flowtable *flowtable,
 	if (!offload)
 		return;
 
-	flow->flags |= FLOW_OFFLOAD_HW;
+	__set_bit(NF_FLOW_HW, &flow->flags);
 	flow_offload_queue_work(offload);
 }
 
@@ -789,7 +789,7 @@ void nf_flow_offload_del(struct nf_flowtable *flowtable,
 	if (!offload)
 		return;
 
-	flow->flags |= FLOW_OFFLOAD_HW_DYING;
+	set_bit(NF_FLOW_HW_DYING, &flow->flags);
 	flow_offload_queue_work(offload);
 }