bpf: Add an example for bpf_get_listener_sock

This patch adds an example in using the new helper
bpf_get_listener_sock().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/bpf_helpers.h

@@ -180,6 +180,8 @@ static struct bpf_sock *(*bpf_sk_fullsock)(struct bpf_sock *sk) =
 	(void *) BPF_FUNC_sk_fullsock;
 static struct bpf_tcp_sock *(*bpf_tcp_sock)(struct bpf_sock *sk) =
 	(void *) BPF_FUNC_tcp_sock;
+static struct bpf_sock *(*bpf_get_listener_sock)(struct bpf_sock *sk) =
+	(void *) BPF_FUNC_get_listener_sock;
 static int (*bpf_skb_ecn_set_ce)(void *ctx) =
 	(void *) BPF_FUNC_skb_ecn_set_ce;
 

tools/testing/selftests/bpf/progs/test_sock_fields_kern.c

@@ -8,38 +8,51 @@
 #include "bpf_helpers.h"
 #include "bpf_endian.h"
 
-enum bpf_array_idx {
-	SRV_IDX,
-	CLI_IDX,
-	__NR_BPF_ARRAY_IDX,
+enum bpf_addr_array_idx {
+	ADDR_SRV_IDX,
+	ADDR_CLI_IDX,
+	__NR_BPF_ADDR_ARRAY_IDX,
+};
+
+enum bpf_result_array_idx {
+	EGRESS_SRV_IDX,
+	EGRESS_CLI_IDX,
+	INGRESS_LISTEN_IDX,
+	__NR_BPF_RESULT_ARRAY_IDX,
+};
+
+enum bpf_linum_array_idx {
+	EGRESS_LINUM_IDX,
+	INGRESS_LINUM_IDX,
+	__NR_BPF_LINUM_ARRAY_IDX,
 };
 
 struct bpf_map_def SEC("maps") addr_map = {
 	.type = BPF_MAP_TYPE_ARRAY,
 	.key_size = sizeof(__u32),
 	.value_size = sizeof(struct sockaddr_in6),
-	.max_entries = __NR_BPF_ARRAY_IDX,
+	.max_entries = __NR_BPF_ADDR_ARRAY_IDX,
 };
 
 struct bpf_map_def SEC("maps") sock_result_map = {
 	.type = BPF_MAP_TYPE_ARRAY,
 	.key_size = sizeof(__u32),
 	.value_size = sizeof(struct bpf_sock),
-	.max_entries = __NR_BPF_ARRAY_IDX,
+	.max_entries = __NR_BPF_RESULT_ARRAY_IDX,
 };
 
 struct bpf_map_def SEC("maps") tcp_sock_result_map = {
 	.type = BPF_MAP_TYPE_ARRAY,
 	.key_size = sizeof(__u32),
 	.value_size = sizeof(struct bpf_tcp_sock),
-	.max_entries = __NR_BPF_ARRAY_IDX,
+	.max_entries = __NR_BPF_RESULT_ARRAY_IDX,
 };
 
 struct bpf_map_def SEC("maps") linum_map = {
 	.type = BPF_MAP_TYPE_ARRAY,
 	.key_size = sizeof(__u32),
 	.value_size = sizeof(__u32),
-	.max_entries = 1,
+	.max_entries = __NR_BPF_LINUM_ARRAY_IDX,
 };
 
 static bool is_loopback6(__u32 *a6)
@@ -100,18 +113,20 @@ static void tpcpy(struct bpf_tcp_sock *dst,
 
 #define RETURN {						\
 	linum = __LINE__;					\
-	bpf_map_update_elem(&linum_map, &idx0, &linum, 0);	\
+	bpf_map_update_elem(&linum_map, &linum_idx, &linum, 0);	\
 	return 1;						\
 }
 
 SEC("cgroup_skb/egress")
-int read_sock_fields(struct __sk_buff *skb)
+int egress_read_sock_fields(struct __sk_buff *skb)
 {
-	__u32 srv_idx = SRV_IDX, cli_idx = CLI_IDX, idx;
+	__u32 srv_idx = ADDR_SRV_IDX, cli_idx = ADDR_CLI_IDX, result_idx;
 	struct sockaddr_in6 *srv_sa6, *cli_sa6;
 	struct bpf_tcp_sock *tp, *tp_ret;
 	struct bpf_sock *sk, *sk_ret;
-	__u32 linum, idx0 = 0;
+	__u32 linum, linum_idx;
+
+	linum_idx = EGRESS_LINUM_IDX;
 
 	sk = skb->sk;
 	if (!sk || sk->state == 10)
@@ -132,14 +147,55 @@ int read_sock_fields(struct __sk_buff *skb)
 		RETURN;
 
 	if (sk->src_port == bpf_ntohs(srv_sa6->sin6_port))
-		idx = srv_idx;
+		result_idx = EGRESS_SRV_IDX;
 	else if (sk->src_port == bpf_ntohs(cli_sa6->sin6_port))
-		idx = cli_idx;
+		result_idx = EGRESS_CLI_IDX;
 	else
 		RETURN;
 
-	sk_ret = bpf_map_lookup_elem(&sock_result_map, &idx);
-	tp_ret = bpf_map_lookup_elem(&tcp_sock_result_map, &idx);
+	sk_ret = bpf_map_lookup_elem(&sock_result_map, &result_idx);
+	tp_ret = bpf_map_lookup_elem(&tcp_sock_result_map, &result_idx);
+	if (!sk_ret || !tp_ret)
+		RETURN;
+
+	skcpy(sk_ret, sk);
+	tpcpy(tp_ret, tp);
+
+	RETURN;
+}
+
+SEC("cgroup_skb/ingress")
+int ingress_read_sock_fields(struct __sk_buff *skb)
+{
+	__u32 srv_idx = ADDR_SRV_IDX, result_idx = INGRESS_LISTEN_IDX;
+	struct bpf_tcp_sock *tp, *tp_ret;
+	struct bpf_sock *sk, *sk_ret;
+	struct sockaddr_in6 *srv_sa6;
+	__u32 linum, linum_idx;
+
+	linum_idx = INGRESS_LINUM_IDX;
+
+	sk = skb->sk;
+	if (!sk || sk->family != AF_INET6 || !is_loopback6(sk->src_ip6))
+		RETURN;
+
+	srv_sa6 = bpf_map_lookup_elem(&addr_map, &srv_idx);
+	if (!srv_sa6 || sk->src_port != bpf_ntohs(srv_sa6->sin6_port))
+		RETURN;
+
+	if (sk->state != 10 && sk->state != 12)
+		RETURN;
+
+	sk = bpf_get_listener_sock(sk);
+	if (!sk)
+		RETURN;
+
+	tp = bpf_tcp_sock(sk);
+	if (!tp)
+		RETURN;
+
+	sk_ret = bpf_map_lookup_elem(&sock_result_map, &result_idx);
+	tp_ret = bpf_map_lookup_elem(&tcp_sock_result_map, &result_idx);
 	if (!sk_ret || !tp_ret)
 		RETURN;
 

tools/testing/selftests/bpf/test_sock_fields.c

@@ -16,10 +16,23 @@
 #include "cgroup_helpers.h"
 #include "bpf_rlimit.h"
 
-enum bpf_array_idx {
-	SRV_IDX,
-	CLI_IDX,
-	__NR_BPF_ARRAY_IDX,
+enum bpf_addr_array_idx {
+	ADDR_SRV_IDX,
+	ADDR_CLI_IDX,
+	__NR_BPF_ADDR_ARRAY_IDX,
+};
+
+enum bpf_result_array_idx {
+	EGRESS_SRV_IDX,
+	EGRESS_CLI_IDX,
+	INGRESS_LISTEN_IDX,
+	__NR_BPF_RESULT_ARRAY_IDX,
+};
+
+enum bpf_linum_array_idx {
+	EGRESS_LINUM_IDX,
+	INGRESS_LINUM_IDX,
+	__NR_BPF_LINUM_ARRAY_IDX,
 };
 
 #define CHECK(condition, tag, format...) ({				\
@@ -41,8 +54,16 @@ static int linum_map_fd;
 static int addr_map_fd;
 static int tp_map_fd;
 static int sk_map_fd;
-static __u32 srv_idx = SRV_IDX;
-static __u32 cli_idx = CLI_IDX;
+
+static __u32 addr_srv_idx = ADDR_SRV_IDX;
+static __u32 addr_cli_idx = ADDR_CLI_IDX;
+
+static __u32 egress_srv_idx = EGRESS_SRV_IDX;
+static __u32 egress_cli_idx = EGRESS_CLI_IDX;
+static __u32 ingress_listen_idx = INGRESS_LISTEN_IDX;
+
+static __u32 egress_linum_idx = EGRESS_LINUM_IDX;
+static __u32 ingress_linum_idx = INGRESS_LINUM_IDX;
 
 static void init_loopback6(struct sockaddr_in6 *sa6)
 {
@@ -93,29 +114,46 @@ static void print_tp(const struct bpf_tcp_sock *tp)
 
 static void check_result(void)
 {
-	struct bpf_tcp_sock srv_tp, cli_tp;
-	struct bpf_sock srv_sk, cli_sk;
-	__u32 linum, idx0 = 0;
+	struct bpf_tcp_sock srv_tp, cli_tp, listen_tp;
+	struct bpf_sock srv_sk, cli_sk, listen_sk;
+	__u32 ingress_linum, egress_linum;
 	int err;
 
-	err = bpf_map_lookup_elem(linum_map_fd, &idx0, &linum);
+	err = bpf_map_lookup_elem(linum_map_fd, &egress_linum_idx,
+				  &egress_linum);
 	CHECK(err == -1, "bpf_map_lookup_elem(linum_map_fd)",
 	      "err:%d errno:%d", err, errno);
 
-	err = bpf_map_lookup_elem(sk_map_fd, &srv_idx, &srv_sk);
-	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &srv_idx)",
+	err = bpf_map_lookup_elem(linum_map_fd, &ingress_linum_idx,
+				  &ingress_linum);
+	CHECK(err == -1, "bpf_map_lookup_elem(linum_map_fd)",
+	      "err:%d errno:%d", err, errno);
+
+	err = bpf_map_lookup_elem(sk_map_fd, &egress_srv_idx, &srv_sk);
+	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &egress_srv_idx)",
+	      "err:%d errno:%d", err, errno);
+	err = bpf_map_lookup_elem(tp_map_fd, &egress_srv_idx, &srv_tp);
+	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &egress_srv_idx)",
+	      "err:%d errno:%d", err, errno);
+
+	err = bpf_map_lookup_elem(sk_map_fd, &egress_cli_idx, &cli_sk);
+	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &egress_cli_idx)",
 	      "err:%d errno:%d", err, errno);
-	err = bpf_map_lookup_elem(tp_map_fd, &srv_idx, &srv_tp);
-	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &srv_idx)",
+	err = bpf_map_lookup_elem(tp_map_fd, &egress_cli_idx, &cli_tp);
+	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &egress_cli_idx)",
 	      "err:%d errno:%d", err, errno);
 
-	err = bpf_map_lookup_elem(sk_map_fd, &cli_idx, &cli_sk);
-	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &cli_idx)",
+	err = bpf_map_lookup_elem(sk_map_fd, &ingress_listen_idx, &listen_sk);
+	CHECK(err == -1, "bpf_map_lookup_elem(sk_map_fd, &ingress_listen_idx)",
 	      "err:%d errno:%d", err, errno);
-	err = bpf_map_lookup_elem(tp_map_fd, &cli_idx, &cli_tp);
-	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &cli_idx)",
+	err = bpf_map_lookup_elem(tp_map_fd, &ingress_listen_idx, &listen_tp);
+	CHECK(err == -1, "bpf_map_lookup_elem(tp_map_fd, &ingress_listen_idx)",
 	      "err:%d errno:%d", err, errno);
 
+	printf("listen_sk: ");
+	print_sk(&listen_sk);
+	printf("\n");
+
 	printf("srv_sk: ");
 	print_sk(&srv_sk);
 	printf("\n");
@@ -124,6 +162,10 @@ static void check_result(void)
 	print_sk(&cli_sk);
 	printf("\n");
 
+	printf("listen_tp: ");
+	print_tp(&listen_tp);
+	printf("\n");
+
 	printf("srv_tp: ");
 	print_tp(&srv_tp);
 	printf("\n");
@@ -132,6 +174,19 @@ static void check_result(void)
 	print_tp(&cli_tp);
 	printf("\n");
 
+	CHECK(listen_sk.state != 10 ||
+	      listen_sk.family != AF_INET6 ||
+	      listen_sk.protocol != IPPROTO_TCP ||
+	      memcmp(listen_sk.src_ip6, &in6addr_loopback,
+		     sizeof(listen_sk.src_ip6)) ||
+	      listen_sk.dst_ip6[0] || listen_sk.dst_ip6[1] ||
+	      listen_sk.dst_ip6[2] || listen_sk.dst_ip6[3] ||
+	      listen_sk.src_port != ntohs(srv_sa6.sin6_port) ||
+	      listen_sk.dst_port,
+	      "Unexpected listen_sk",
+	      "Check listen_sk output. ingress_linum:%u",
+	      ingress_linum);
+
 	CHECK(srv_sk.state == 10 ||
 	      !srv_sk.state ||
 	      srv_sk.family != AF_INET6 ||
@@ -142,7 +197,8 @@ static void check_result(void)
 		     sizeof(srv_sk.dst_ip6)) ||
 	      srv_sk.src_port != ntohs(srv_sa6.sin6_port) ||
 	      srv_sk.dst_port != cli_sa6.sin6_port,
-	      "Unexpected srv_sk", "Check srv_sk output. linum:%u", linum);
+	      "Unexpected srv_sk", "Check srv_sk output. egress_linum:%u",
+	      egress_linum);
 
 	CHECK(cli_sk.state == 10 ||
 	      !cli_sk.state ||
@@ -154,21 +210,31 @@ static void check_result(void)
 		     sizeof(cli_sk.dst_ip6)) ||
 	      cli_sk.src_port != ntohs(cli_sa6.sin6_port) ||
 	      cli_sk.dst_port != srv_sa6.sin6_port,
-	      "Unexpected cli_sk", "Check cli_sk output. linum:%u", linum);
+	      "Unexpected cli_sk", "Check cli_sk output. egress_linum:%u",
+	      egress_linum);
+
+	CHECK(listen_tp.data_segs_out ||
+	      listen_tp.data_segs_in ||
+	      listen_tp.total_retrans ||
+	      listen_tp.bytes_acked,
+	      "Unexpected listen_tp", "Check listen_tp output. ingress_linum:%u",
+	      ingress_linum);
 
 	CHECK(srv_tp.data_segs_out != 1 ||
 	      srv_tp.data_segs_in ||
 	      srv_tp.snd_cwnd != 10 ||
 	      srv_tp.total_retrans ||
 	      srv_tp.bytes_acked != DATA_LEN,
-	      "Unexpected srv_tp", "Check srv_tp output. linum:%u", linum);
+	      "Unexpected srv_tp", "Check srv_tp output. egress_linum:%u",
+	      egress_linum);
 
 	CHECK(cli_tp.data_segs_out ||
 	      cli_tp.data_segs_in != 1 ||
 	      cli_tp.snd_cwnd != 10 ||
 	      cli_tp.total_retrans ||
 	      cli_tp.bytes_received != DATA_LEN,
-	      "Unexpected cli_tp", "Check cli_tp output. linum:%u", linum);
+	      "Unexpected cli_tp", "Check cli_tp output. egress_linum:%u",
+	      egress_linum);
 }
 
 static void test(void)
@@ -211,10 +277,10 @@ static void test(void)
 	      err, errno);
 
 	/* Update addr_map with srv_sa6 and cli_sa6 */
-	err = bpf_map_update_elem(addr_map_fd, &srv_idx, &srv_sa6, 0);
+	err = bpf_map_update_elem(addr_map_fd, &addr_srv_idx, &srv_sa6, 0);
 	CHECK(err, "map_update", "err:%d errno:%d", err, errno);
 
-	err = bpf_map_update_elem(addr_map_fd, &cli_idx, &cli_sa6, 0);
+	err = bpf_map_update_elem(addr_map_fd, &addr_cli_idx, &cli_sa6, 0);
 	CHECK(err, "map_update", "err:%d errno:%d", err, errno);
 
 	/* Connect from cli_sa6 to srv_sa6 */
@@ -273,9 +339,9 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr attr = {
 		.file = "test_sock_fields_kern.o",
 		.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
-		.expected_attach_type = BPF_CGROUP_INET_EGRESS,
 	};
-	int cgroup_fd, prog_fd, err;
+	int cgroup_fd, egress_fd, ingress_fd, err;
+	struct bpf_program *ingress_prog;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 
@@ -293,12 +359,24 @@ int main(int argc, char **argv)
 	err = join_cgroup(TEST_CGROUP);
 	CHECK(err, "join_cgroup", "err:%d errno:%d", err, errno);
 
-	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+	err = bpf_prog_load_xattr(&attr, &obj, &egress_fd);
 	CHECK(err, "bpf_prog_load_xattr()", "err:%d", err);
 
-	err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_INET_EGRESS, 0);
+	ingress_prog = bpf_object__find_program_by_title(obj,
+							 "cgroup_skb/ingress");
+	CHECK(!ingress_prog,
+	      "bpf_object__find_program_by_title(cgroup_skb/ingress)",
+	      "not found");
+	ingress_fd = bpf_program__fd(ingress_prog);
+
+	err = bpf_prog_attach(egress_fd, cgroup_fd, BPF_CGROUP_INET_EGRESS, 0);
 	CHECK(err == -1, "bpf_prog_attach(CPF_CGROUP_INET_EGRESS)",
 	      "err:%d errno%d", err, errno);
+
+	err = bpf_prog_attach(ingress_fd, cgroup_fd,
+			      BPF_CGROUP_INET_INGRESS, 0);
+	CHECK(err == -1, "bpf_prog_attach(CPF_CGROUP_INET_INGRESS)",
+	      "err:%d errno%d", err, errno);
 	close(cgroup_fd);
 
 	map = bpf_object__find_map_by_name(obj, "addr_map");