bpf: introduce skb map

Insert skb into skb map at position @key:
bpf_skb_push(&map, skb, key);

Remove the skb at position @key from skb map:
skb = bpf_skb_pop(&map, key);

Peek an skb by @key:
skb = bpf_map_lookup_elem(&map, &key);

Drop the skb at position @key:
bpf_map_delete_elem(&map, &key);

Iterate all the skbs in the map in order:
bpf_for_each_map_elem(&skb_map, skb_callback, key, skb);

Signed-off-by: Cong Wang <cong.wang@bytedance.com>

include/linux/bpf.h

@@ -2273,6 +2273,10 @@ extern const struct bpf_func_proto bpf_loop_proto;
 extern const struct bpf_func_proto bpf_strncmp_proto;
 extern const struct bpf_func_proto bpf_copy_from_user_task_proto;
 extern const struct bpf_func_proto bpf_kptr_xchg_proto;
+extern const struct bpf_func_proto bpf_skb_map_push_proto;
+extern const struct bpf_func_proto bpf_skb_map_pop_proto;
+extern const struct bpf_func_proto bpf_flow_map_push_proto;
+extern const struct bpf_func_proto bpf_flow_map_pop_proto;
 
 const struct bpf_func_proto *tracing_prog_func_proto(
   enum bpf_func_id func_id, const struct bpf_prog *prog);

include/linux/bpf_types.h

@@ -110,6 +110,8 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_DEVMAP, dev_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_DEVMAP_HASH, dev_map_hash_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_SK_STORAGE, sk_storage_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_CPUMAP, cpu_map_ops)
+BPF_MAP_TYPE(BPF_MAP_TYPE_SKBMAP, skb_map_ops)
+BPF_MAP_TYPE(BPF_MAP_TYPE_FLOWMAP, flow_map_ops)
 #if defined(CONFIG_XDP_SOCKETS)
 BPF_MAP_TYPE(BPF_MAP_TYPE_XSKMAP, xsk_map_ops)
 #endif

include/linux/skbuff.h

@@ -1017,7 +1017,9 @@ struct sk_buff {
 				unsigned long		dev_scratch;
 			};
 		};
-		struct rb_node		rbnode; /* used in netem, ip4 defrag, and tcp stack */
+		struct rb_node		rbnode; /* used in eBPF skb map, netem, ip4 defrag, and tcp
+						 * stack
+						 */
 		struct list_head	list;
 		struct llist_node	ll_node;
 	};

include/uapi/linux/bpf.h

@@ -909,6 +909,8 @@ enum bpf_map_type {
 	BPF_MAP_TYPE_INODE_STORAGE,
 	BPF_MAP_TYPE_TASK_STORAGE,
 	BPF_MAP_TYPE_BLOOM_FILTER,
+	BPF_MAP_TYPE_SKBMAP,
+	BPF_MAP_TYPE_FLOWMAP,
 };
 
 /* Note that tracing related programs such as
@@ -5455,6 +5457,10 @@ union bpf_attr {
 	FN(dynptr_read),		\
 	FN(dynptr_write),		\
 	FN(dynptr_data),		\
+	FN(skb_map_push),		\
+	FN(skb_map_pop),		\
+	FN(flow_map_push),		\
+	FN(flow_map_pop),		\
 	/* */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper

kernel/bpf/verifier.c

@@ -6264,6 +6264,16 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
 		    func_id != BPF_FUNC_map_push_elem)
 			goto error;
 		break;
+	case BPF_MAP_TYPE_SKBMAP:
+		if (func_id != BPF_FUNC_skb_map_push &&
+		    func_id != BPF_FUNC_skb_map_pop)
+			goto error;
+		break;
+	case BPF_MAP_TYPE_FLOWMAP:
+		if (func_id != BPF_FUNC_flow_map_push &&
+		    func_id != BPF_FUNC_flow_map_pop)
+			goto error;
+		break;
 	default:
 		break;
 	}

net/core/Makefile

@@ -38,4 +38,5 @@ obj-$(CONFIG_FAILOVER) += failover.o
 obj-$(CONFIG_NET_SOCK_MSG) += skmsg.o
 obj-$(CONFIG_BPF_SYSCALL) += sock_map.o
 obj-$(CONFIG_BPF_SYSCALL) += bpf_sk_storage.o
+obj-$(CONFIG_BPF_SYSCALL) += skb_map.o
 obj-$(CONFIG_OF)	+= of_net.o