flow_dissector: implements flow dissector BPF hook

Adds a hook for programs of type BPF_PROG_TYPE_FLOW_DISSECTOR and
attach type BPF_FLOW_DISSECTOR that is executed in the flow dissector
path. The BPF program is per-network namespace.

Signed-off-by: Petar Penkov <ppenkov@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

6 files changed, 47 insertions, 3 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 523481a3471b..988a00797bcd 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -212,6 +212,7 @@ enum bpf_reg_type {
 	PTR_TO_PACKET_META,	 /* skb->data - meta_len */
 	PTR_TO_PACKET,		 /* reg points to skb->data */
 	PTR_TO_PACKET_END,	 /* skb->data + headlen */
+	PTR_TO_FLOW_KEYS,	 /* reg points to bpf_flow_keys */
 };
 
 /* The information passed from prog-specific *_is_valid_access
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index cd26c090e7c0..22083712dd18 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -32,6 +32,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
 #ifdef CONFIG_INET
 BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
 #endif
+BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
 
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 17a13e4785fc..ce0e863f02a2 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -243,6 +243,8 @@ struct scatterlist;
 struct pipe_inode_info;
 struct iov_iter;
 struct napi_struct;
+struct bpf_prog;
+union bpf_attr;
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 struct nf_conntrack {
@@ -1192,6 +1194,11 @@ void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
 			     const struct flow_dissector_key *key,
 			     unsigned int key_count);
 
+int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
+				       struct bpf_prog *prog);
+
+int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
+
 bool __skb_flow_dissect(const struct sk_buff *skb,
 			struct flow_dissector *flow_dissector,
 			void *target_container,
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 9b5fdc50519a..99d4148e0f90 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -43,6 +43,7 @@ struct ctl_table_header;
 struct net_generic;
 struct uevent_sock;
 struct netns_ipvs;
+struct bpf_prog;
 
 
 #define NETDEV_HASHBITS    8
@@ -145,6 +146,8 @@ struct net {
 #endif
 	struct net_generic __rcu	*gen;
 
+	struct bpf_prog __rcu	*flow_dissector_prog;
+
 	/* Note : following structs are cache line aligned */
 #ifdef CONFIG_XFRM
 	struct netns_xfrm	xfrm;
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index a6d00093f35e..1b81ba85fd2d 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -19,6 +19,7 @@ struct Qdisc_ops;
 struct qdisc_walker;
 struct tcf_walker;
 struct module;
+struct bpf_flow_keys;
 
 typedef int tc_setup_cb_t(enum tc_setup_type type,
 			  void *type_data, void *cb_priv);
@@ -307,9 +308,14 @@ struct tcf_proto {
 };
 
 struct qdisc_skb_cb {
-	unsigned int		pkt_len;
-	u16			slave_dev_queue_mapping;
-	u16			tc_classid;
+	union {
+		struct {
+			unsigned int		pkt_len;
+			u16			slave_dev_queue_mapping;
+			u16			tc_classid;
+		};
+		struct bpf_flow_keys *flow_keys;
+	};
 #define QDISC_CB_PRIV_LEN 20
 	unsigned char		data[QDISC_CB_PRIV_LEN];
 };
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 66917a4eba27..aa5ccd2385ed 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -152,6 +152,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_LWT_SEG6LOCAL,
 	BPF_PROG_TYPE_LIRC_MODE2,
 	BPF_PROG_TYPE_SK_REUSEPORT,
+	BPF_PROG_TYPE_FLOW_DISSECTOR,
 };
 
 enum bpf_attach_type {
@@ -172,6 +173,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_UDP4_SENDMSG,
 	BPF_CGROUP_UDP6_SENDMSG,
 	BPF_LIRC_MODE2,
+	BPF_FLOW_DISSECTOR,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -2333,6 +2335,7 @@ struct __sk_buff {
 	/* ... here. */
 
 	__u32 data_meta;
+	struct bpf_flow_keys *flow_keys;
 };
 
 struct bpf_tunnel_key {
@@ -2778,4 +2781,27 @@ enum bpf_task_fd_type {
 	BPF_FD_TYPE_URETPROBE,		/* filename + offset */
 };
 
+struct bpf_flow_keys {
+	__u16	nhoff;
+	__u16	thoff;
+	__u16	addr_proto;			/* ETH_P_* of valid addrs */
+	__u8	is_frag;
+	__u8	is_first_frag;
+	__u8	is_encap;
+	__u8	ip_proto;
+	__be16	n_proto;
+	__be16	sport;
+	__be16	dport;
+	union {
+		struct {
+			__be32	ipv4_src;
+			__be32	ipv4_dst;
+		};
+		struct {
+			__u32	ipv6_src[4];	/* in6_addr; network order */
+			__u32	ipv6_dst[4];	/* in6_addr; network order */
+		};
+	};
+};
+
 #endif /* _UAPI__LINUX_BPF_H__ */