selftests/bpf: add l4 load balancer test based on sched_cls

this l4lb demo is a comprehensive test case for LLVM codegen and
kernel verifier. It's using fully inlined jhash(), complex packet
parsing and multiple map lookups of different types to stress
llvm and verifier.
The map sizes, map population and test vectors are artificial to
exercise different paths through the bpf program.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/bpf/Makefile

@@ -6,7 +6,7 @@ LDLIBS += -lcap -lelf
 
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs
 
-TEST_GEN_FILES = test_pkt_access.o test_xdp.o
+TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o
 
 TEST_PROGS := test_kmod.sh
 

tools/testing/selftests/bpf/test_progs.c

@@ -28,11 +28,14 @@ typedef __u16 __sum16;
 #include <bpf/bpf.h>
 #include <bpf/libbpf.h>
 #include "test_iptunnel_common.h"
+#include "bpf_util.h"
 
 #define _htons __builtin_bswap16
 
 static int error_cnt, pass_cnt;
 
+#define MAGIC_BYTES 123
+
 /* ipv4 test vector */
 static struct {
 	struct ethhdr eth;
@@ -42,6 +45,7 @@ static struct {
 	.eth.h_proto = _htons(ETH_P_IP),
 	.iph.ihl = 5,
 	.iph.protocol = 6,
+	.iph.tot_len = _htons(MAGIC_BYTES),
 	.tcp.urg_ptr = 123,
 };
 
@@ -53,6 +57,7 @@ static struct {
 } __packed pkt_v6 = {
 	.eth.h_proto = _htons(ETH_P_IPV6),
 	.iph.nexthdr = 6,
+	.iph.payload_len = _htons(MAGIC_BYTES),
 	.tcp.urg_ptr = 123,
 };
 
@@ -182,6 +187,88 @@ static void test_xdp(void)
 	bpf_object__close(obj);
 }
 
+#define MAGIC_VAL 0x1234
+#define NUM_ITER 100000
+#define VIP_NUM 5
+
+static void test_l4lb(void)
+{
+	unsigned int nr_cpus = bpf_num_possible_cpus();
+	const char *file = "./test_l4lb.o";
+	struct vip key = {.protocol = 6};
+	struct vip_meta {
+		__u32 flags;
+		__u32 vip_num;
+	} value = {.vip_num = VIP_NUM};
+	__u32 stats_key = VIP_NUM;
+	struct vip_stats {
+		__u64 bytes;
+		__u64 pkts;
+	} stats[nr_cpus];
+	struct real_definition {
+		union {
+			__be32 dst;
+			__be32 dstv6[4];
+		};
+		__u8 flags;
+	} real_def = {.dst = MAGIC_VAL};
+	__u32 ch_key = 11, real_num = 3;
+	__u32 duration, retval, size;
+	int err, i, prog_fd, map_fd;
+	__u64 bytes = 0, pkts = 0;
+	struct bpf_object *obj;
+	char buf[128];
+	u32 *magic = (u32 *)buf;
+
+	err = bpf_prog_load(file, BPF_PROG_TYPE_SCHED_CLS, &obj, &prog_fd);
+	if (err)
+		return;
+
+	map_fd = bpf_find_map(__func__, obj, "vip_map");
+	if (map_fd < 0)
+		goto out;
+	bpf_map_update_elem(map_fd, &key, &value, 0);
+
+	map_fd = bpf_find_map(__func__, obj, "ch_rings");
+	if (map_fd < 0)
+		goto out;
+	bpf_map_update_elem(map_fd, &ch_key, &real_num, 0);
+
+	map_fd = bpf_find_map(__func__, obj, "reals");
+	if (map_fd < 0)
+		goto out;
+	bpf_map_update_elem(map_fd, &real_num, &real_def, 0);
+
+	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v4, sizeof(pkt_v4),
+				buf, &size, &retval, &duration);
+	CHECK(err || errno || retval != 7/*TC_ACT_REDIRECT*/ || size != 54 ||
+	      *magic != MAGIC_VAL, "ipv4",
+	      "err %d errno %d retval %d size %d magic %x\n",
+	      err, errno, retval, size, *magic);
+
+	err = bpf_prog_test_run(prog_fd, NUM_ITER, &pkt_v6, sizeof(pkt_v6),
+				buf, &size, &retval, &duration);
+	CHECK(err || errno || retval != 7/*TC_ACT_REDIRECT*/ || size != 74 ||
+	      *magic != MAGIC_VAL, "ipv6",
+	      "err %d errno %d retval %d size %d magic %x\n",
+	      err, errno, retval, size, *magic);
+
+	map_fd = bpf_find_map(__func__, obj, "stats");
+	if (map_fd < 0)
+		goto out;
+	bpf_map_lookup_elem(map_fd, &stats_key, stats);
+	for (i = 0; i < nr_cpus; i++) {
+		bytes += stats[i].bytes;
+		pkts += stats[i].pkts;
+	}
+	if (bytes != MAGIC_BYTES * NUM_ITER * 2 || pkts != NUM_ITER * 2) {
+		error_cnt++;
+		printf("test_l4lb:FAIL:stats %lld %lld\n", bytes, pkts);
+	}
+out:
+	bpf_object__close(obj);
+}
+
 int main(void)
 {
 	struct rlimit rinf = { RLIM_INFINITY, RLIM_INFINITY };
@@ -190,6 +277,7 @@ int main(void)
 
 	test_pkt_access();
 	test_xdp();
+	test_l4lb();
 
 	printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
 	return 0;