Re: [PATCH bpf-next v2 1/2] bpf: Add ifindex to bpf_sk_lookup

It may be helpful to have access to the ifindex during bpf socket
lookup. An example may be to scope certain socket lookup logic to
specific interfaces, i.e. an interface may be made exempt from custom
lookup code.

Add the ifindex of the arriving connection to the bpf_sk_lookup API.

Signed-off-by: Mark Pashmfouroush <redacted>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 24b7ed2677af..0012a5176a32 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h

@@ -1374,6 +1374,7 @@ struct bpf_sk_lookup_kern {
  		const struct in6_addr *daddr;
  	} v6;
  	struct sock	*selected_sk;
+	u32		ifindex;

  	bool		no_reuseport;
  };
  

@@ -1436,7 +1437,7 @@ extern struct static_key_false bpf_sk_lookup_enabled;
  static inline bool bpf_sk_lookup_run_v4(struct net *net, int protocol,
  					const __be32 saddr, const __be16 sport,
  					const __be32 daddr, const u16 dport,
-					struct sock **psk)
+					const int ifindex, struct sock **psk)
  {
  	struct bpf_prog_array *run_array;
  	struct sock *selected_sk = NULL;

@@ -1452,6 +1453,7 @@ static inline bool bpf_sk_lookup_run_v4(struct net *net, int protocol,
  			.v4.daddr	= daddr,
  			.sport		= sport,
  			.dport		= dport,
+			.ifindex	= ifindex,
  		};
  		u32 act;
  

@@ -1474,7 +1476,7 @@ static inline bool bpf_sk_lookup_run_v6(struct net *net, int protocol,
  					const __be16 sport,
  					const struct in6_addr *daddr,
  					const u16 dport,
-					struct sock **psk)
+					const int ifindex, struct sock **psk)
  {
  	struct bpf_prog_array *run_array;
  	struct sock *selected_sk = NULL;

@@ -1490,6 +1492,7 @@ static inline bool bpf_sk_lookup_run_v6(struct net *net, int protocol,
  			.v6.daddr	= daddr,
  			.sport		= sport,
  			.dport		= dport,
+			.ifindex	= ifindex,
  		};
  		u32 act;
  

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index ba5af15e25f5..5b8618a4d485 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h

@@ -6296,6 +6296,7 @@ struct bpf_sk_lookup {
  	__u32 local_ip4;	/* Network byte order */
  	__u32 local_ip6[4];	/* Network byte order */
  	__u32 local_port;	/* Host byte order */
+	__u32 ifindex;		/* The arriving interface. Determined by inet_iif. */
  };