[PATCH bpf-next 3/3] selftests/bpf: Add tests for writing to nf_conn:mark

[Daniel Xu <dxu@xxxxxxxxx>]

Add a simple extension to the existing selftest to write to
nf_conn:mark. Also add a failure test for writing to unsupported field.

Signed-off-by: Daniel Xu <dxu@xxxxxxxxx>
---
 tools/testing/selftests/bpf/prog_tests/bpf_nf.c    |  1 +
 tools/testing/selftests/bpf/progs/test_bpf_nf.c    |  6 ++++--
 .../testing/selftests/bpf/progs/test_bpf_nf_fail.c | 14 ++++++++++++++
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_nf.c b/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
index 544bf90ac2a7..45389c39f211 100644
--- a/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
+++ b/tools/testing/selftests/bpf/prog_tests/bpf_nf.c
@@ -17,6 +17,7 @@ struct {
 	{ "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" },
+	{ "write_not_allowlisted_field", "no write support to nf_conn at off" },
 };
 
 enum {
diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf.c b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
index 2722441850cc..638b6642d20f 100644
--- a/tools/testing/selftests/bpf/progs/test_bpf_nf.c
+++ b/tools/testing/selftests/bpf/progs/test_bpf_nf.c
@@ -175,8 +175,10 @@ nf_ct_test(struct nf_conn *(*lookup_fn)(void *, struct bpf_sock_tuple *, u32,
 		       sizeof(opts_def));
 	if (ct) {
 		test_exist_lookup = 0;
-		if (ct->mark == 42)
-			test_exist_lookup_mark = 43;
+		if (ct->mark == 42) {
+			ct->mark++;
+			test_exist_lookup_mark = ct->mark;
+		}
 		bpf_ct_release(ct);
 	} else {
 		test_exist_lookup = opts_def.error;
diff --git a/tools/testing/selftests/bpf/progs/test_bpf_nf_fail.c b/tools/testing/selftests/bpf/progs/test_bpf_nf_fail.c
index bf79af15c808..0e4759ab38ff 100644
--- a/tools/testing/selftests/bpf/progs/test_bpf_nf_fail.c
+++ b/tools/testing/selftests/bpf/progs/test_bpf_nf_fail.c
@@ -69,6 +69,20 @@ int lookup_insert(struct __sk_buff *ctx)
 	return 0;
 }
 
+SEC("?tc")
+int write_not_allowlisted_field(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;
+	ct->status = 0xF00;
+	return 0;
+}
+
 SEC("?tc")
 int set_timeout_after_insert(struct __sk_buff *ctx)
 {
-- 
2.37.1