net: core: Add filter config option

Add this config option to reduce memory usage, if it was not necessary.

./ksize.sh net

before size: 716596 Bytes
after  size: 673095 Bytes
save   size: 43501  Bytes

Signed-off-by: David Wu <david.wu@rock-chips.com>
Change-Id: I012d926a7a8be9a4897a85fbf47f7fbbab1e43c4

include/linux/filter.h

@@ -761,7 +761,16 @@ bpf_jit_binary_hdr(const struct bpf_prog *fp)
 	return (void *)addr;
 }
 
+#ifdef CONFIG_FILTER
 int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap);
+#else
+static inline
+int sk_filter_trim_cap(struct sock *sk, struct sk_buff *skb, unsigned int cap)
+{
+	return 0;
+}
+#endif
+
 static inline int sk_filter(struct sock *sk, struct sk_buff *skb)
 {
 	return sk_filter_trim_cap(sk, skb, 1);
@@ -786,6 +795,7 @@ static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
 typedef int (*bpf_aux_classic_check_t)(struct sock_filter *filter,
 				       unsigned int flen);
 
+#ifdef CONFIG_FILTER
 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
 int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog,
 			      bpf_aux_classic_check_t trans, bool save_orig);
@@ -803,6 +813,71 @@ int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 
+#else
+static inline
+int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog)
+{
+	return 0;
+}
+
+static inline
+int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog,
+			      bpf_aux_classic_check_t trans, bool save_orig)
+{
+	return 0;
+}
+
+static inline void bpf_prog_destroy(struct bpf_prog *fp)
+{
+}
+
+static inline int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
+{
+	return 0;
+}
+
+static inline int sk_attach_bpf(u32 ufd, struct sock *sk)
+{
+	return 0;
+}
+
+static inline
+int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk)
+{
+	return 0;
+}
+
+static inline int sk_reuseport_attach_bpf(u32 ufd, struct sock *sk)
+{
+	return 0;
+}
+
+static inline void sk_reuseport_prog_free(struct bpf_prog *prog)
+{
+}
+
+static inline int sk_detach_filter(struct sock *sk)
+{
+	return 0;
+}
+
+static inline
+int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
+		  unsigned int len)
+{
+	return 0;
+}
+
+static inline bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
+{
+	return false;
+}
+
+static inline void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)
+{
+}
+#endif
+
 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 #define __bpf_call_base_args \
 	((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \
@@ -861,6 +936,7 @@ static inline int xdp_ok_fwd_dev(const struct net_device *fwd,
 	return 0;
 }
 
+#ifdef CONFIG_FILTER
 /* The pair of xdp_do_redirect and xdp_do_flush_map MUST be called in the
  * same cpu context. Further for best results no more than a single map
  * for the do_redirect/do_flush pair should be used. This limitation is
@@ -875,11 +951,35 @@ int xdp_do_redirect(struct net_device *dev,
 void xdp_do_flush_map(void);
 
 void bpf_warn_invalid_xdp_action(u32 act);
+#else
+static inline
+int xdp_do_generic_redirect(struct net_device *dev, struct sk_buff *skb,
+			    struct xdp_buff *xdp, struct bpf_prog *prog)
+{
+	return 0;
+}
+
+static inline
+int xdp_do_redirect(struct net_device *dev,
+		    struct xdp_buff *xdp,
+		    struct bpf_prog *prog)
+{
+	return 0;
+}
+
+static inline void xdp_do_flush_map(void)
+{
+}
+
+static inline void bpf_warn_invalid_xdp_action(u32 act)
+{
+}
+#endif
 
 struct sock *do_sk_redirect_map(struct sk_buff *skb);
 struct sock *do_msg_redirect_map(struct sk_msg_buff *md);
 
-#ifdef CONFIG_INET
+#if (IS_ENABLED(CONFIG_INET) && IS_ENABLED(CONFIG_FILTER))
 struct sock *bpf_run_sk_reuseport(struct sock_reuseport *reuse, struct sock *sk,
 				  struct bpf_prog *prog, struct sk_buff *skb,
 				  u32 hash);

net/Kconfig

@@ -316,6 +316,13 @@ config ETHTOOL
 	  This selects ethtool function, default is Y. If say N, ethtool function
 	  is not implemented.
 
+config FILTER
+	bool "enable filter"
+	default y
+	help
+	  This selects filter function, default is Y. If say N, filter function
+	  is not implemented.
+
 config NET_FLOW_LIMIT
 	bool
 	depends on RPS

net/core/Makefile

@@ -9,10 +9,11 @@ obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \
 obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
 
 obj-y		     += dev.o dev_addr_lists.o dst.o netevent.o \
-			neighbour.o rtnetlink.o utils.o link_watch.o filter.o \
+			neighbour.o rtnetlink.o utils.o link_watch.o \
 			sock_diag.o dev_ioctl.o tso.o sock_reuseport.o \
 			fib_notifier.o xdp.o
 
+obj-$(CONFIG_FILTER) += filter.o
 obj-$(CONFIG_ETHTOOL) += ethtool.o
 obj-y += net-sysfs.o
 obj-$(CONFIG_PAGE_POOL) += page_pool.o