selftests/bpf: Add test for unstable CT lookup API

This tests that we return errors as documented, and also that the kfunc
calls work from both XDP and TC hooks.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-8-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/config

@@ -48,3 +48,7 @@ CONFIG_IMA_READ_POLICY=y
 CONFIG_BLK_DEV_LOOP=y
 CONFIG_FUNCTION_TRACER=y
 CONFIG_DYNAMIC_FTRACE=y
+CONFIG_NETFILTER=y
+CONFIG_NF_DEFRAG_IPV4=y
+CONFIG_NF_DEFRAG_IPV6=y
+CONFIG_NF_CONNTRACK=y

tools/testing/selftests/bpf/prog_tests/bpf_nf.c

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "test_bpf_nf.skel.h"
+
+enum {
+	TEST_XDP,
+	TEST_TC_BPF,
+};
+
+void test_bpf_nf_ct(int mode)
+{
+	struct test_bpf_nf *skel;
+	int prog_fd, err, retval;
+
+	skel = test_bpf_nf__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "test_bpf_nf__open_and_load"))
+		return;
+
+	if (mode == TEST_XDP)
+		prog_fd = bpf_program__fd(skel->progs.nf_xdp_ct_test);
+	else
+		prog_fd = bpf_program__fd(skel->progs.nf_skb_ct_test);
+
+	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4), NULL, NULL,
+				(__u32 *)&retval, NULL);
+	if (!ASSERT_OK(err, "bpf_prog_test_run"))
+		goto end;
+
+	ASSERT_EQ(skel->bss->test_einval_bpf_tuple, -EINVAL, "Test EINVAL for NULL bpf_tuple");
+	ASSERT_EQ(skel->bss->test_einval_reserved, -EINVAL, "Test EINVAL for reserved not set to 0");
+	ASSERT_EQ(skel->bss->test_einval_netns_id, -EINVAL, "Test EINVAL for netns_id < -1");
+	ASSERT_EQ(skel->bss->test_einval_len_opts, -EINVAL, "Test EINVAL for len__opts != NF_BPF_CT_OPTS_SZ");
+	ASSERT_EQ(skel->bss->test_eproto_l4proto, -EPROTO, "Test EPROTO for l4proto != TCP or UDP");
+	ASSERT_EQ(skel->bss->test_enonet_netns_id, -ENONET, "Test ENONET for bad but valid netns_id");
+	ASSERT_EQ(skel->bss->test_enoent_lookup, -ENOENT, "Test ENOENT for failed lookup");
+	ASSERT_EQ(skel->bss->test_eafnosupport, -EAFNOSUPPORT, "Test EAFNOSUPPORT for invalid len__tuple");
+end:
+	test_bpf_nf__destroy(skel);
+}
+
+void test_bpf_nf(void)
+{
+	if (test__start_subtest("xdp-ct"))
+		test_bpf_nf_ct(TEST_XDP);
+	if (test__start_subtest("tc-bpf-ct"))
+		test_bpf_nf_ct(TEST_TC_BPF);
+}

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

@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+#define EAFNOSUPPORT 97
+#define EPROTO 71
+#define ENONET 64
+#define EINVAL 22
+#define ENOENT 2
+
+int test_einval_bpf_tuple = 0;
+int test_einval_reserved = 0;
+int test_einval_netns_id = 0;
+int test_einval_len_opts = 0;
+int test_eproto_l4proto = 0;
+int test_enonet_netns_id = 0;
+int test_enoent_lookup = 0;
+int test_eafnosupport = 0;
+
+struct nf_conn *bpf_xdp_ct_lookup(struct xdp_md *, struct bpf_sock_tuple *, u32,
+				  struct bpf_ct_opts *, u32) __ksym;
+struct nf_conn *bpf_skb_ct_lookup(struct __sk_buff *, struct bpf_sock_tuple *, u32,
+				  struct bpf_ct_opts *, u32) __ksym;
+void bpf_ct_release(struct nf_conn *) __ksym;
+
+static __always_inline void
+nf_ct_test(struct nf_conn *(*func)(void *, struct bpf_sock_tuple *, u32,
+				   struct bpf_ct_opts *, u32),
+	   void *ctx)
+{
+	struct bpf_ct_opts opts_def = { .l4proto = IPPROTO_TCP, .netns_id = -1 };
+	struct bpf_sock_tuple bpf_tuple;
+	struct nf_conn *ct;
+
+	__builtin_memset(&bpf_tuple, 0, sizeof(bpf_tuple.ipv4));
+
+	ct = func(ctx, NULL, 0, &opts_def, sizeof(opts_def));
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_einval_bpf_tuple = opts_def.error;
+
+	opts_def.reserved[0] = 1;
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def));
+	opts_def.reserved[0] = 0;
+	opts_def.l4proto = IPPROTO_TCP;
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_einval_reserved = opts_def.error;
+
+	opts_def.netns_id = -2;
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def));
+	opts_def.netns_id = -1;
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_einval_netns_id = opts_def.error;
+
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def) - 1);
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_einval_len_opts = opts_def.error;
+
+	opts_def.l4proto = IPPROTO_ICMP;
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def));
+	opts_def.l4proto = IPPROTO_TCP;
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_eproto_l4proto = opts_def.error;
+
+	opts_def.netns_id = 0xf00f;
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def));
+	opts_def.netns_id = -1;
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_enonet_netns_id = opts_def.error;
+
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4), &opts_def, sizeof(opts_def));
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_enoent_lookup = opts_def.error;
+
+	ct = func(ctx, &bpf_tuple, sizeof(bpf_tuple.ipv4) - 1, &opts_def, sizeof(opts_def));
+	if (ct)
+		bpf_ct_release(ct);
+	else
+		test_eafnosupport = opts_def.error;
+}
+
+SEC("xdp")
+int nf_xdp_ct_test(struct xdp_md *ctx)
+{
+	nf_ct_test((void *)bpf_xdp_ct_lookup, ctx);
+	return 0;
+}
+
+SEC("tc")
+int nf_skb_ct_test(struct __sk_buff *ctx)
+{
+	nf_ct_test((void *)bpf_skb_ct_lookup, ctx);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";