bpf/flow_dissector: support flags in BPF_PROG_TEST_RUN

This will allow us to write tests for those flags.

v2:
* Swap kfree(data) and kfree(user_ctx) (Song Liu)
Acked-by: Petar Penkov <ppenkov@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Petar Penkov <ppenkov@google.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/bpf/test_run.c

@@ -377,6 +377,22 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	return ret;
 }
 
+static int verify_user_bpf_flow_keys(struct bpf_flow_keys *ctx)
+{
+	/* make sure the fields we don't use are zeroed */
+	if (!range_is_zero(ctx, 0, offsetof(struct bpf_flow_keys, flags)))
+		return -EINVAL;
+
+	/* flags is allowed */
+
+	if (!range_is_zero(ctx, offsetof(struct bpf_flow_keys, flags) +
+			   FIELD_SIZEOF(struct bpf_flow_keys, flags),
+			   sizeof(struct bpf_flow_keys)))
+		return -EINVAL;
+
+	return 0;
+}
+
 int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 				     const union bpf_attr *kattr,
 				     union bpf_attr __user *uattr)
@@ -384,9 +400,11 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	u32 size = kattr->test.data_size_in;
 	struct bpf_flow_dissector ctx = {};
 	u32 repeat = kattr->test.repeat;
+	struct bpf_flow_keys *user_ctx;
 	struct bpf_flow_keys flow_keys;
 	u64 time_start, time_spent = 0;
 	const struct ethhdr *eth;
+	unsigned int flags = 0;
 	u32 retval, duration;
 	void *data;
 	int ret;
@@ -395,9 +413,6 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
 		return -EINVAL;
 
-	if (kattr->test.ctx_in || kattr->test.ctx_out)
-		return -EINVAL;
-
 	if (size < ETH_HLEN)
 		return -EINVAL;
 
@@ -410,6 +425,18 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	if (!repeat)
 		repeat = 1;
 
+	user_ctx = bpf_ctx_init(kattr, sizeof(struct bpf_flow_keys));
+	if (IS_ERR(user_ctx)) {
+		kfree(data);
+		return PTR_ERR(user_ctx);
+	}
+	if (user_ctx) {
+		ret = verify_user_bpf_flow_keys(user_ctx);
+		if (ret)
+			goto out;
+		flags = user_ctx->flags;
+	}
+
 	ctx.flow_keys = &flow_keys;
 	ctx.data = data;
 	ctx.data_end = (__u8 *)data + size;
@@ -419,7 +446,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	time_start = ktime_get_ns();
 	for (i = 0; i < repeat; i++) {
 		retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
-					  size, 0);
+					  size, flags);
 
 		if (signal_pending(current)) {
 			preempt_enable();
@@ -450,8 +477,12 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 
 	ret = bpf_test_finish(kattr, uattr, &flow_keys, sizeof(flow_keys),
 			      retval, duration);
+	if (!ret)
+		ret = bpf_ctx_finish(kattr, uattr, user_ctx,
+				     sizeof(struct bpf_flow_keys));
 
 out:
+	kfree(user_ctx);
 	kfree(data);
 	return ret;
 }