bpf: Add test_sock_fields for skb->sk and bpf_tcp_sock

This patch adds a C program to show the usage on
skb->sk and bpf_tcp_sock.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/Makefile

@@ -23,7 +23,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
 	test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
 	test_sock test_btf test_sockmap test_lirc_mode2_user get_cgroup_id_user \
 	test_socket_cookie test_cgroup_storage test_select_reuseport test_section_names \
-	test_netcnt test_tcpnotify_user
+	test_netcnt test_tcpnotify_user test_sock_fields
 
 BPF_OBJ_FILES = \
 	test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o \
@@ -35,7 +35,8 @@ BPF_OBJ_FILES = \
 	sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
 	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
 	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o test_xdp_vlan.o \
-	xdp_dummy.o test_map_in_map.o test_spin_lock.o test_map_lock.o
+	xdp_dummy.o test_map_in_map.o test_spin_lock.o test_map_lock.o \
+	test_sock_fields_kern.o
 
 # Objects are built with default compilation flags and with sub-register
 # code-gen enabled.
@@ -111,6 +112,7 @@ $(OUTPUT)/test_progs: trace_helpers.c
 $(OUTPUT)/get_cgroup_id_user: cgroup_helpers.c
 $(OUTPUT)/test_cgroup_storage: cgroup_helpers.c
 $(OUTPUT)/test_netcnt: cgroup_helpers.c
+$(OUTPUT)/test_sock_fields: cgroup_helpers.c
 
 .PHONY: force
 

tools/testing/selftests/bpf/bpf_helpers.h

@@ -176,6 +176,10 @@ static void (*bpf_spin_lock)(struct bpf_spin_lock *lock) =
 	(void *) BPF_FUNC_spin_lock;
 static void (*bpf_spin_unlock)(struct bpf_spin_lock *lock) =
 	(void *) BPF_FUNC_spin_unlock;
+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;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions

tools/testing/selftests/bpf/test_sock_fields_kern.c

+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2019 Facebook */
+
+#include <linux/bpf.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+enum bpf_array_idx {
+	SRV_IDX,
+	CLI_IDX,
+	__NR_BPF_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,
+};
+
+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,
+};
+
+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,
+};
+
+struct bpf_map_def SEC("maps") linum_map = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+};
+
+static bool is_loopback6(__u32 *a6)
+{
+	return !a6[0] && !a6[1] && !a6[2] && a6[3] == bpf_htonl(1);
+}
+
+static void skcpy(struct bpf_sock *dst,
+		  const struct bpf_sock *src)
+{
+	dst->bound_dev_if = src->bound_dev_if;
+	dst->family = src->family;
+	dst->type = src->type;
+	dst->protocol = src->protocol;
+	dst->mark = src->mark;
+	dst->priority = src->priority;
+	dst->src_ip4 = src->src_ip4;
+	dst->src_ip6[0] = src->src_ip6[0];
+	dst->src_ip6[1] = src->src_ip6[1];
+	dst->src_ip6[2] = src->src_ip6[2];
+	dst->src_ip6[3] = src->src_ip6[3];
+	dst->src_port = src->src_port;
+	dst->dst_ip4 = src->dst_ip4;
+	dst->dst_ip6[0] = src->dst_ip6[0];
+	dst->dst_ip6[1] = src->dst_ip6[1];
+	dst->dst_ip6[2] = src->dst_ip6[2];
+	dst->dst_ip6[3] = src->dst_ip6[3];
+	dst->dst_port = src->dst_port;
+	dst->state = src->state;
+}
+
+static void tpcpy(struct bpf_tcp_sock *dst,
+		  const struct bpf_tcp_sock *src)
+{
+	dst->snd_cwnd = src->snd_cwnd;
+	dst->srtt_us = src->srtt_us;
+	dst->rtt_min = src->rtt_min;
+	dst->snd_ssthresh = src->snd_ssthresh;
+	dst->rcv_nxt = src->rcv_nxt;
+	dst->snd_nxt = src->snd_nxt;
+	dst->snd_una = src->snd_una;
+	dst->mss_cache = src->mss_cache;
+	dst->ecn_flags = src->ecn_flags;
+	dst->rate_delivered = src->rate_delivered;
+	dst->rate_interval_us = src->rate_interval_us;
+	dst->packets_out = src->packets_out;
+	dst->retrans_out = src->retrans_out;
+	dst->total_retrans = src->total_retrans;
+	dst->segs_in = src->segs_in;
+	dst->data_segs_in = src->data_segs_in;
+	dst->segs_out = src->segs_out;
+	dst->data_segs_out = src->data_segs_out;
+	dst->lost_out = src->lost_out;
+	dst->sacked_out = src->sacked_out;
+	dst->bytes_received = src->bytes_received;
+	dst->bytes_acked = src->bytes_acked;
+}
+
+#define RETURN {						\
+	linum = __LINE__;					\
+	bpf_map_update_elem(&linum_map, &idx0, &linum, 0);	\
+	return 1;						\
+}
+
+SEC("cgroup_skb/egress")
+int read_sock_fields(struct __sk_buff *skb)
+{
+	__u32 srv_idx = SRV_IDX, cli_idx = CLI_IDX, 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;
+
+	sk = skb->sk;
+	if (!sk || sk->state == 10)
+		RETURN;
+
+	sk = bpf_sk_fullsock(sk);
+	if (!sk || sk->family != AF_INET6 || sk->protocol != IPPROTO_TCP ||
+	    !is_loopback6(sk->src_ip6))
+		RETURN;
+
+	tp = bpf_tcp_sock(sk);
+	if (!tp)
+		RETURN;
+
+	srv_sa6 = bpf_map_lookup_elem(&addr_map, &srv_idx);
+	cli_sa6 = bpf_map_lookup_elem(&addr_map, &cli_idx);
+	if (!srv_sa6 || !cli_sa6)
+		RETURN;
+
+	if (sk->src_port == bpf_ntohs(srv_sa6->sin6_port))
+		idx = srv_idx;
+	else if (sk->src_port == bpf_ntohs(cli_sa6->sin6_port))
+		idx = 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);
+	if (!sk_ret || !tp_ret)
+		RETURN;
+
+	skcpy(sk_ret, sk);
+	tpcpy(tp_ret, tp);
+
+	RETURN;
+}
+
+char _license[] SEC("license") = "GPL";