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>

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 2d0a0d141793ef8ab860bc4df023dba659ad7146..f8d2b2a13131f48eaab6e300fa7876bd035ddab1 100644 (file)
--- 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;