selftests/bpf: Add selftests for the invocation of bpf_lwt_xmit_push_encap

Calling bpf_lwt_xmit_push_encap will not cause a crash when dst is missing.

Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20260304094429.168521-3-yangfeng59949@163.com

diff --git a/tools/testing/selftests/bpf/prog_tests/lwt_misc.c b/tools/testing/selftests/bpf/prog_tests/lwt_misc.c
new file mode 100644 (file)
index 0000000..6940fca
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/lwt_misc.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include "lwt_misc.skel.h"
+
+void test_lwt_misc(void)
+{
+       RUN_TESTS(lwt_misc);
+}

diff --git a/tools/testing/selftests/bpf/progs/lwt_misc.c b/tools/testing/selftests/bpf/progs/lwt_misc.c
new file mode 100644 (file)
index 0000000..b392317
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/lwt_misc.c
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+SEC("lwt_xmit")
+__success __retval(0)
+int test_missing_dst(struct __sk_buff *skb)
+{
+       struct iphdr iph;
+
+       __builtin_memset(&iph, 0, sizeof(struct iphdr));
+       iph.ihl = 5;
+       iph.version = 4;
+
+       bpf_lwt_push_encap(skb, BPF_LWT_ENCAP_IP, &iph, sizeof(struct iphdr));
+
+       return 0;
+}
+
+char _license[] SEC("license") = "GPL";