selftests/bpf: Add negative tests for new nf_conntrack kfuncs

Test cases we care about and ensure improper usage is caught and
rejected by the verifier.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-13-memxor@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

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

@@ -2,13 +2,29 @@
 #include <test_progs.h>
 #include <network_helpers.h>
 #include "test_bpf_nf.skel.h"
+#include "test_bpf_nf_fail.skel.h"
+
+static char log_buf[1024 * 1024];
+
+struct {
+	const char *prog_name;
+	const char *err_msg;
+} test_bpf_nf_fail_tests[] = {
+	{ "alloc_release", "kernel function bpf_ct_release args#0 expected pointer to STRUCT nf_conn but" },
+	{ "insert_insert", "kernel function bpf_ct_insert_entry args#0 expected pointer to STRUCT nf_conn___init but" },
+	{ "lookup_insert", "kernel function bpf_ct_insert_entry args#0 expected pointer to STRUCT nf_conn___init but" },
+	{ "set_timeout_after_insert", "kernel function bpf_ct_set_timeout args#0 expected pointer to STRUCT nf_conn___init but" },
+	{ "set_status_after_insert", "kernel function bpf_ct_set_status args#0 expected pointer to STRUCT nf_conn___init but" },
+	{ "change_timeout_after_alloc", "kernel function bpf_ct_change_timeout args#0 expected pointer to STRUCT nf_conn but" },
+	{ "change_status_after_alloc", "kernel function bpf_ct_change_status args#0 expected pointer to STRUCT nf_conn but" },
+};
 
 enum {
 	TEST_XDP,
 	TEST_TC_BPF,
 };
 
-void test_bpf_nf_ct(int mode)
+static void test_bpf_nf_ct(int mode)
 {
 	struct test_bpf_nf *skel;
 	int prog_fd, err;
@@ -51,10 +67,48 @@ void test_bpf_nf_ct(int mode)
 	test_bpf_nf__destroy(skel);
 }
 
+static void test_bpf_nf_ct_fail(const char *prog_name, const char *err_msg)
+{
+	LIBBPF_OPTS(bpf_object_open_opts, opts, .kernel_log_buf = log_buf,
+						.kernel_log_size = sizeof(log_buf),
+						.kernel_log_level = 1);
+	struct test_bpf_nf_fail *skel;
+	struct bpf_program *prog;
+	int ret;
+
+	skel = test_bpf_nf_fail__open_opts(&opts);
+	if (!ASSERT_OK_PTR(skel, "test_bpf_nf_fail__open"))
+		return;
+
+	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
+	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+		goto end;
+
+	bpf_program__set_autoload(prog, true);
+
+	ret = test_bpf_nf_fail__load(skel);
+	if (!ASSERT_ERR(ret, "test_bpf_nf_fail__load must fail"))
+		goto end;
+
+	if (!ASSERT_OK_PTR(strstr(log_buf, err_msg), "expected error message")) {
+		fprintf(stderr, "Expected: %s\n", err_msg);
+		fprintf(stderr, "Verifier: %s\n", log_buf);
+	}
+
+end:
+	test_bpf_nf_fail__destroy(skel);
+}
+
 void test_bpf_nf(void)
 {
+	int i;
 	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);
+	for (i = 0; i < ARRAY_SIZE(test_bpf_nf_fail_tests); i++) {
+		if (test__start_subtest(test_bpf_nf_fail_tests[i].prog_name))
+			test_bpf_nf_ct_fail(test_bpf_nf_fail_tests[i].prog_name,
+					    test_bpf_nf_fail_tests[i].err_msg);
+	}
 }

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

+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_core_read.h>
+
+struct nf_conn;
+
+struct bpf_ct_opts___local {
+	s32 netns_id;
+	s32 error;
+	u8 l4proto;
+	u8 reserved[3];
+} __attribute__((preserve_access_index));
+
+struct nf_conn *bpf_skb_ct_alloc(struct __sk_buff *, struct bpf_sock_tuple *, u32,
+				 struct bpf_ct_opts___local *, u32) __ksym;
+struct nf_conn *bpf_skb_ct_lookup(struct __sk_buff *, struct bpf_sock_tuple *, u32,
+				  struct bpf_ct_opts___local *, u32) __ksym;
+struct nf_conn *bpf_ct_insert_entry(struct nf_conn *) __ksym;
+void bpf_ct_release(struct nf_conn *) __ksym;
+void bpf_ct_set_timeout(struct nf_conn *, u32) __ksym;
+int bpf_ct_change_timeout(struct nf_conn *, u32) __ksym;
+int bpf_ct_set_status(struct nf_conn *, u32) __ksym;
+int bpf_ct_change_status(struct nf_conn *, u32) __ksym;
+
+SEC("?tc")
+int alloc_release(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	bpf_ct_release(ct);
+	return 0;
+}
+
+SEC("?tc")
+int insert_insert(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	ct = bpf_ct_insert_entry(ct);
+	if (!ct)
+		return 0;
+	ct = bpf_ct_insert_entry(ct);
+	return 0;
+}
+
+SEC("?tc")
+int lookup_insert(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_lookup(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	bpf_ct_insert_entry(ct);
+	return 0;
+}
+
+SEC("?tc")
+int set_timeout_after_insert(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	ct = bpf_ct_insert_entry(ct);
+	if (!ct)
+		return 0;
+	bpf_ct_set_timeout(ct, 0);
+	return 0;
+}
+
+SEC("?tc")
+int set_status_after_insert(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	ct = bpf_ct_insert_entry(ct);
+	if (!ct)
+		return 0;
+	bpf_ct_set_status(ct, 0);
+	return 0;
+}
+
+SEC("?tc")
+int change_timeout_after_alloc(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	bpf_ct_change_timeout(ct, 0);
+	return 0;
+}
+
+SEC("?tc")
+int change_status_after_alloc(struct __sk_buff *ctx)
+{
+	struct bpf_ct_opts___local opts = {};
+	struct bpf_sock_tuple tup = {};
+	struct nf_conn *ct;
+
+	ct = bpf_skb_ct_alloc(ctx, &tup, sizeof(tup.ipv4), &opts, sizeof(opts));
+	if (!ct)
+		return 0;
+	bpf_ct_change_status(ct, 0);
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";