samples: bpf: Convert xdp_router_ipv4 to XDP samples helper

Rely on the libbpf skeleton facility and other utilities provided by XDP
sample helpers in xdp_router_ipv4 sample.
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/7f4d98ee2c13c04d5eb924eebf79ced32fee8418.1647414711.git.lorenzo@kernel.org

samples/bpf/Makefile

@@ -96,7 +96,6 @@ test_cgrp2_sock2-objs := test_cgrp2_sock2.o
 xdp1-objs := xdp1_user.o
 # reuse xdp1 source intentionally
 xdp2-objs := xdp1_user.o
-xdp_router_ipv4-objs := xdp_router_ipv4_user.o
 test_current_task_under_cgroup-objs := $(CGROUP_HELPERS) \
 				       test_current_task_under_cgroup_user.o
 trace_event-objs := trace_event_user.o $(TRACE_HELPERS)
@@ -124,6 +123,7 @@ xdp_redirect_cpu-objs := xdp_redirect_cpu_user.o $(XDP_SAMPLE)
 xdp_redirect_map-objs := xdp_redirect_map_user.o $(XDP_SAMPLE)
 xdp_redirect-objs := xdp_redirect_user.o $(XDP_SAMPLE)
 xdp_monitor-objs := xdp_monitor_user.o $(XDP_SAMPLE)
+xdp_router_ipv4-objs := xdp_router_ipv4_user.o $(XDP_SAMPLE)
 
 # Tell kbuild to always build the programs
 always-y := $(tprogs-y)
@@ -153,7 +153,6 @@ always-y += parse_varlen.o parse_simple.o parse_ldabs.o
 always-y += test_cgrp2_tc_kern.o
 always-y += xdp1_kern.o
 always-y += xdp2_kern.o
-always-y += xdp_router_ipv4_kern.o
 always-y += test_current_task_under_cgroup_kern.o
 always-y += trace_event_kern.o
 always-y += sampleip_kern.o
@@ -342,6 +341,7 @@ $(obj)/xdp_redirect_map_multi_user.o: $(obj)/xdp_redirect_map_multi.skel.h
 $(obj)/xdp_redirect_map_user.o: $(obj)/xdp_redirect_map.skel.h
 $(obj)/xdp_redirect_user.o: $(obj)/xdp_redirect.skel.h
 $(obj)/xdp_monitor_user.o: $(obj)/xdp_monitor.skel.h
+$(obj)/xdp_router_ipv4_user.o: $(obj)/xdp_router_ipv4.skel.h
 
 $(obj)/tracex5_kern.o: $(obj)/syscall_nrs.h
 $(obj)/hbm_out_kern.o: $(src)/hbm.h $(src)/hbm_kern.h
@@ -399,6 +399,7 @@ $(obj)/xdp_redirect_map_multi.bpf.o: $(obj)/xdp_sample.bpf.o
 $(obj)/xdp_redirect_map.bpf.o: $(obj)/xdp_sample.bpf.o
 $(obj)/xdp_redirect.bpf.o: $(obj)/xdp_sample.bpf.o
 $(obj)/xdp_monitor.bpf.o: $(obj)/xdp_sample.bpf.o
+$(obj)/xdp_router_ipv4.bpf.o: $(obj)/xdp_sample.bpf.o
 
 $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/xdp_sample_shared.h
 	@echo "  CLANG-BPF " $@
@@ -409,7 +410,8 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(obj)/vmlinux.h $(src)/xdp_sample.bpf.h $(src)/x
 		-c $(filter %.bpf.c,$^) -o $@
 
 LINKED_SKELS := xdp_redirect_cpu.skel.h xdp_redirect_map_multi.skel.h \
-		xdp_redirect_map.skel.h xdp_redirect.skel.h xdp_monitor.skel.h
+		xdp_redirect_map.skel.h xdp_redirect.skel.h xdp_monitor.skel.h \
+		xdp_router_ipv4.skel.h
 clean-files += $(LINKED_SKELS)
 
 xdp_redirect_cpu.skel.h-deps := xdp_redirect_cpu.bpf.o xdp_sample.bpf.o
@@ -417,6 +419,7 @@ xdp_redirect_map_multi.skel.h-deps := xdp_redirect_map_multi.bpf.o xdp_sample.bp
 xdp_redirect_map.skel.h-deps := xdp_redirect_map.bpf.o xdp_sample.bpf.o
 xdp_redirect.skel.h-deps := xdp_redirect.bpf.o xdp_sample.bpf.o
 xdp_monitor.skel.h-deps := xdp_monitor.bpf.o xdp_sample.bpf.o
+xdp_router_ipv4.skel.h-deps := xdp_router_ipv4.bpf.o xdp_sample.bpf.o
 
 LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
 

samples/bpf/xdp_router_ipv4_kern.c → samples/bpf/xdp_router_ipv4.bpf.c

@@ -4,17 +4,14 @@
  * under the terms of version 2 of the GNU General Public License
  * as published by the Free Software Foundation.
  */
-#define KBUILD_MODNAME "foo"
-#include <uapi/linux/bpf.h>
-#include <linux/in.h>
-#include <linux/if_ether.h>
-#include <linux/if_packet.h>
-#include <linux/if_vlan.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <bpf/bpf_helpers.h>
-#include <linux/slab.h>
-#include <net/ip_fib.h>
+
+#include "vmlinux.h"
+#include "xdp_sample.bpf.h"
+#include "xdp_sample_shared.h"
+
+#define ETH_ALEN	6
+#define ETH_P_8021Q	0x8100
+#define ETH_P_8021AD	0x88A8
 
 struct trie_value {
 	__u8 prefix[4];
@@ -24,7 +21,7 @@ struct trie_value {
 	__be32 gw;
 };
 
-/* Key for lpm_trie*/
+/* Key for lpm_trie */
 union key_4 {
 	u32 b32[2];
 	u8 b8[8];
@@ -41,7 +38,7 @@ struct direct_map {
 	__be64 mac;
 };
 
-/* Map for trie implementation*/
+/* Map for trie implementation */
 struct {
 	__uint(type, BPF_MAP_TYPE_LPM_TRIE);
 	__uint(key_size, 8);
@@ -50,15 +47,7 @@ struct {
 	__uint(map_flags, BPF_F_NO_PREALLOC);
 } lpm_map SEC(".maps");
 
-/* Map for counter*/
-struct {
-	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
-	__type(key, u32);
-	__type(value, u64);
-	__uint(max_entries, 256);
-} rxcnt SEC(".maps");
-
-/* Map for ARP table*/
+/* Map for ARP table */
 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
 	__type(key, __be32);
@@ -66,7 +55,7 @@ struct {
 	__uint(max_entries, 50);
 } arp_table SEC(".maps");
 
-/* Map to keep the exact match entries in the route table*/
+/* Map to keep the exact match entries in the route table */
 struct {
 	__uint(type, BPF_MAP_TYPE_HASH);
 	__type(key, __be32);
@@ -81,106 +70,111 @@ struct {
 	__uint(max_entries, 100);
 } tx_port SEC(".maps");
 
-/* Function to set source and destination mac of the packet */
-static inline void set_src_dst_mac(void *data, void *src, void *dst)
-{
-	unsigned short *source = src;
-	unsigned short *dest  = dst;
-	unsigned short *p = data;
-
-	__builtin_memcpy(p, dest, 6);
-	__builtin_memcpy(p + 3, source, 6);
-}
-
-/* Parse IPV4 packet to get SRC, DST IP and protocol */
-static inline int parse_ipv4(void *data, u64 nh_off, void *data_end,
-			     __be32 *src, __be32 *dest)
-{
-	struct iphdr *iph = data + nh_off;
-
-	if (iph + 1 > data_end)
-		return 0;
-	*src = iph->saddr;
-	*dest = iph->daddr;
-	return iph->protocol;
-}
-
-SEC("xdp_router_ipv4")
+SEC("xdp")
 int xdp_router_ipv4_prog(struct xdp_md *ctx)
 {
 	void *data_end = (void *)(long)ctx->data_end;
-	__be64 *dest_mac = NULL, *src_mac = NULL;
 	void *data = (void *)(long)ctx->data;
-	struct trie_value *prefix_value;
-	int rc = XDP_DROP, forward_to;
 	struct ethhdr *eth = data;
-	union key_4 key4;
-	long *value;
-	u16 h_proto;
-	u32 ipproto;
-	u64 nh_off;
+	u64 nh_off = sizeof(*eth);
+	struct datarec *rec;
+	__be16 h_proto;
+	u32 key = 0;
+
+	rec = bpf_map_lookup_elem(&rx_cnt, &key);
+	if (rec)
+		NO_TEAR_INC(rec->processed);
 
-	nh_off = sizeof(*eth);
 	if (data + nh_off > data_end)
-		return rc;
+		goto drop;
 
 	h_proto = eth->h_proto;
-
-	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
+	if (h_proto == bpf_htons(ETH_P_8021Q) ||
+	    h_proto == bpf_htons(ETH_P_8021AD)) {
 		struct vlan_hdr *vhdr;
 
 		vhdr = data + nh_off;
 		nh_off += sizeof(struct vlan_hdr);
 		if (data + nh_off > data_end)
-			return rc;
+			goto drop;
+
 		h_proto = vhdr->h_vlan_encapsulated_proto;
 	}
-	if (h_proto == htons(ETH_P_ARP)) {
+
+	switch (bpf_ntohs(h_proto)) {
+	case ETH_P_ARP:
+		if (rec)
+			NO_TEAR_INC(rec->xdp_pass);
 		return XDP_PASS;
-	} else if (h_proto == htons(ETH_P_IP)) {
+	case ETH_P_IP: {
+		struct iphdr *iph = data + nh_off;
 		struct direct_map *direct_entry;
-		__be32 src_ip = 0, dest_ip = 0;
+		__be64 *dest_mac, *src_mac;
+		int forward_to;
 
-		ipproto = parse_ipv4(data, nh_off, data_end, &src_ip, &dest_ip);
-		direct_entry = bpf_map_lookup_elem(&exact_match, &dest_ip);
-		/* Check for exact match, this would give a faster lookup*/
-		if (direct_entry && direct_entry->mac && direct_entry->arp.mac) {
+		if (iph + 1 > data_end)
+			goto drop;
+
+		direct_entry = bpf_map_lookup_elem(&exact_match, &iph->daddr);
+
+		/* Check for exact match, this would give a faster lookup */
+		if (direct_entry && direct_entry->mac &&
+		    direct_entry->arp.mac) {
 			src_mac = &direct_entry->mac;
 			dest_mac = &direct_entry->arp.mac;
 			forward_to = direct_entry->ifindex;
 		} else {
-			/* Look up in the trie for lpm*/
+			struct trie_value *prefix_value;
+			union key_4 key4;
+
+			/* Look up in the trie for lpm */
 			key4.b32[0] = 32;
-			key4.b8[4] = dest_ip & 0xff;
-			key4.b8[5] = (dest_ip >> 8) & 0xff;
-			key4.b8[6] = (dest_ip >> 16) & 0xff;
-			key4.b8[7] = (dest_ip >> 24) & 0xff;
+			key4.b8[4] = iph->daddr & 0xff;
+			key4.b8[5] = (iph->daddr >> 8) & 0xff;
+			key4.b8[6] = (iph->daddr >> 16) & 0xff;
+			key4.b8[7] = (iph->daddr >> 24) & 0xff;
+
 			prefix_value = bpf_map_lookup_elem(&lpm_map, &key4);
 			if (!prefix_value)
-				return XDP_DROP;
+				goto drop;
+
+			forward_to = prefix_value->ifindex;
 			src_mac = &prefix_value->value;
 			if (!src_mac)
-				return XDP_DROP;
-			dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
+				goto drop;
+
+			dest_mac = bpf_map_lookup_elem(&arp_table, &iph->daddr);
 			if (!dest_mac) {
 				if (!prefix_value->gw)
-					return XDP_DROP;
-				dest_ip = prefix_value->gw;
-				dest_mac = bpf_map_lookup_elem(&arp_table, &dest_ip);
+					goto drop;
+
+				dest_mac = bpf_map_lookup_elem(&arp_table,
+							       &prefix_value->gw);
+			}
+		}
+
+		if (src_mac && dest_mac) {
+			int ret;
+
+			__builtin_memcpy(eth->h_dest, dest_mac, ETH_ALEN);
+			__builtin_memcpy(eth->h_source, src_mac, ETH_ALEN);
+
+			ret = bpf_redirect_map(&tx_port, forward_to, 0);
+			if (ret == XDP_REDIRECT) {
+				if (rec)
+					NO_TEAR_INC(rec->xdp_redirect);
+				return ret;
 			}
-			forward_to = prefix_value->ifindex;
 		}
-	} else {
-		ipproto = 0;
 	}
-	if (src_mac && dest_mac) {
-		set_src_dst_mac(data, src_mac, dest_mac);
-		value = bpf_map_lookup_elem(&rxcnt, &ipproto);
-		if (value)
-			*value += 1;
-		return  bpf_redirect_map(&tx_port, forward_to, 0);
+	default:
+		break;
 	}
-	return rc;
+drop:
+	if (rec)
+		NO_TEAR_INC(rec->xdp_drop);
+
+	return XDP_DROP;
 }
 
 char _license[] SEC("license") = "GPL";