[PATCH bpf-next v3 1/3] selftests/bpf: Add existing connection bpf_*_ct_lookup() test

From: Daniel Xu
Date: Wed Aug 10 2022 - 19:17:07 EST


Add a test where we do a conntrack lookup on an existing connection.
This is nice because it's a more realistic test than artifically
creating a ct entry and looking it up afterwards.

Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
---
.../testing/selftests/bpf/prog_tests/bpf_nf.c | 59 +++++++++++++++++++
.../testing/selftests/bpf/progs/test_bpf_nf.c | 18 ++++++
2 files changed, 77 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_nf.c b/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
index 7a74a1579076..317978cac029 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
@@ -24,10 +24,34 @@ enum {
TEST_TC_BPF,
};

+#define TIMEOUT_MS 3000
+
+static int connect_to_server(int srv_fd)
+{
+ int fd = -1;
+
+ fd = socket(AF_INET, SOCK_STREAM, 0);
+ if (!ASSERT_GE(fd, 0, "socket"))
+ goto out;
+
+ if (CHECK_FAIL(connect_fd_to_fd(fd, srv_fd, TIMEOUT_MS))) {
+ close(fd);
+ fd = -1;
+ }
+out:
+ return fd;
+}
+
static void test_bpf_nf_ct(int mode)
{
+ const char *iptables = "iptables -t raw %s PREROUTING -j CT";
+ int srv_fd = -1, client_fd = -1, srv_client_fd = -1;
+ struct sockaddr_in peer_addr = {};
struct test_bpf_nf *skel;
int prog_fd, err;
+ socklen_t len;
+ u16 srv_port;
+ char cmd[64];
LIBBPF_OPTS(bpf_test_run_opts, topts,
.data_in = &pkt_v4,
.data_size_in = sizeof(pkt_v4),
@@ -38,6 +62,32 @@ static void test_bpf_nf_ct(int mode)
if (!ASSERT_OK_PTR(skel, "test_bpf_nf__open_and_load"))
return;

+ /* Enable connection tracking */
+ snprintf(cmd, sizeof(cmd), iptables, "-A");
+ if (!ASSERT_OK(system(cmd), "iptables"))
+ goto end;
+
+ srv_port = (mode == TEST_XDP) ? 5005 : 5006;
+ srv_fd = start_server(AF_INET, SOCK_STREAM, "127.0.0.1", srv_port, TIMEOUT_MS);
+ if (!ASSERT_GE(srv_fd, 0, "start_server"))
+ goto end;
+
+ client_fd = connect_to_server(srv_fd);
+ if (!ASSERT_GE(client_fd, 0, "connect_to_server"))
+ goto end;
+
+ len = sizeof(peer_addr);
+ srv_client_fd = accept(srv_fd, (struct sockaddr *)&peer_addr, &len);
+ if (!ASSERT_GE(srv_client_fd, 0, "accept"))
+ goto end;
+ if (!ASSERT_EQ(len, sizeof(struct sockaddr_in), "sockaddr len"))
+ goto end;
+
+ skel->bss->saddr = peer_addr.sin_addr.s_addr;
+ skel->bss->sport = peer_addr.sin_port;
+ skel->bss->daddr = peer_addr.sin_addr.s_addr;
+ skel->bss->dport = htons(srv_port);
+
if (mode == TEST_XDP)
prog_fd = bpf_program__fd(skel->progs.nf_xdp_ct_test);
else
@@ -63,7 +113,16 @@ static void test_bpf_nf_ct(int mode)
ASSERT_LE(skel->bss->test_delta_timeout, 10, "Test for max ct timeout update");
/* expected status is IPS_SEEN_REPLY */
ASSERT_EQ(skel->bss->test_status, 2, "Test for ct status update ");
+ ASSERT_EQ(skel->data->test_exist_lookup, 0, "Test existing connection lookup");
end:
+ if (srv_client_fd != -1)
+ close(srv_client_fd);
+ if (client_fd != -1)
+ close(client_fd);
+ if (srv_fd != -1)
+ close(srv_fd);
+ snprintf(cmd, sizeof(cmd), iptables, "-D");
+ system(cmd);
test_bpf_nf__destroy(skel);
}

diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf.c b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
index 196cd8dfe42a..84e0fd479794 100644
--- a/tools/testing/selftests/bpf/progs/test_bpf_nf.c
+++ b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
@@ -23,6 +23,11 @@ int test_insert_entry = -EAFNOSUPPORT;
int test_succ_lookup = -ENOENT;
u32 test_delta_timeout = 0;
u32 test_status = 0;
+__be32 saddr = 0;
+__be16 sport = 0;
+__be32 daddr = 0;
+__be16 dport = 0;
+int test_exist_lookup = -ENOENT;

struct nf_conn;

@@ -160,6 +165,19 @@ nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
}
test_alloc_entry = 0;
}
+
+ bpf_tuple.ipv4.saddr = saddr;
+ bpf_tuple.ipv4.daddr = daddr;
+ bpf_tuple.ipv4.sport = sport;
+ bpf_tuple.ipv4.dport = dport;
+ ct = lookup_fn(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def,
+ sizeof(opts_def));
+ if (ct) {
+ test_exist_lookup = 0;
+ bpf_ct_release(ct);
+ } else {
+ test_exist_lookup = opts_def.error;
+ }
}

SEC("xdp")
--
2.37.1