bpf: Fix bpf_prog_test_run_xdp logic after incorrect merge resolution

During recent net into net-next merge ([0]) a piece of old logic ([1]) got
reintroduced accidentally while resolving merge conflict between bpf's [2]
and bpf-next's [3]. This check was removed in bpf-next tree to allow extra
ctx_in parameter passed for XDP test runs. Reinstating the check breaks
bpf_prog_test_run_xdp logic and causes a corresponding xdp_context_test_run
selftest failure. Fix by removing the check and allow ctx_in for XDP test
runs.

  [0] 5af84df9 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
  [1] 947e8b59 ("bpf: explicitly prohibit ctx_{in, out} in non-skb BPF_PROG_TEST_RUN")
  [2] 5e21bb4e ("bpf, test: fix NULL pointer dereference on invalid expected_attach_type")
  [3] 47316f4a ("bpf: Support input xdp_md context in BPF_PROG_TEST_RUN")

Fixes: 5af84df9 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>

net/bpf/test_run.c

@@ -763,8 +763,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	if (prog->expected_attach_type == BPF_XDP_DEVMAP ||
 	    prog->expected_attach_type == BPF_XDP_CPUMAP)
 		return -EINVAL;
-	if (kattr->test.ctx_in || kattr->test.ctx_out)
-		return -EINVAL;
+
 	ctx = bpf_ctx_init(kattr, sizeof(struct xdp_md));
 	if (IS_ERR(ctx))
 		return PTR_ERR(ctx);