[PATCH v2] selftests/bpf: Validate UDP length in cls_redirect test

[Suchit Karunakaran]

From: Suchit <suchitkarunaka...@gmail.com>

Add validation step to ensure that the UDP payload is
long enough to contain the expected GUE and UNIGUE encapsulation
headers

Signed-off-by: Suchit <suchitkarunaka...@gmail.com>
---

Changes since v2:
- Rebase

 tools/testing/selftests/bpf/progs/test_cls_redirect.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/progs/test_cls_redirect.c 
b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
index f344c6835e84..c1d2eaee2e77 100644
--- a/tools/testing/selftests/bpf/progs/test_cls_redirect.c
+++ b/tools/testing/selftests/bpf/progs/test_cls_redirect.c
@@ -978,7 +978,14 @@ int cls_redirect(struct __sk_buff *skb)
                return TC_ACT_OK;
        }
 
-       /* TODO Check UDP length? */
+       uint16_t udp_len = bpf_ntohs(encap->udp.len);
+       uint16_t min_encap_len = sizeof(encap->udp) + sizeof(encap->gue) + 
sizeof(encap->unigue);
+
+       if (udp_len < min_encap_len) {
+               metrics->errors_total_malformed_encapsulation++;
+               return TC_ACT_SHOT;
+       }
+
        if (encap->udp.dest != ENCAPSULATION_PORT) {
                return TC_ACT_OK;
        }
-- 
2.49.0