net: filter: add test for loading SKF_AD_OFF limits

This check tests that overloading BPF_LD | BPF_ABS with an
always invalid BPF extension, that is SKF_AD_MAX, fails to
make sure classic BPF behaviour is correct in filter checker.

Also, we add a test for loading at packet offset SKF_AD_OFF-1
which should pass the filter, but later on fail during runtime.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 2d0a0d141793..f8d2b2a13131 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -1655,6 +1655,28 @@ static struct bpf_test tests[] = {
                 { },
                 { { 0, 0x2a5a5e5 } },
         },
+        {
+                "check: SKF_AD_MAX",
+                .u.insns = {
+                        BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
+                                 SKF_AD_OFF + SKF_AD_MAX),
+                        BPF_STMT(BPF_RET | BPF_A, 0),
+                },
+                CLASSIC | FLAG_NO_DATA | FLAG_EXPECTED_FAIL,
+                { },
+                { },
+        },
+        {       /* Passes checker but fails during runtime. */
+                "LD [SKF_AD_OFF-1]",
+                .u.insns = {
+                        BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
+                                 SKF_AD_OFF - 1),
+                        BPF_STMT(BPF_RET | BPF_K, 1),
+                },
+                CLASSIC,
+                { },
+                { { 1, 0 } },
+        },
 };
 
 static struct net_device dev;