bpf: when doing BPF_PROG_TEST_RUN for flow dissector use no-skb mode

Now that we have bpf_flow_dissect which can work on raw data,
use it when doing BPF_PROG_TEST_RUN for flow dissector.

Simplifies bpf_prog_test_run_flow_dissector and allows us to
test no-skb mode.

Note, that previously, with bpf_flow_dissect_skb we used to call
eth_type_trans which pulled L2 (ETH_HLEN) header and we explicitly called
skb_reset_network_header. That means flow_keys->nhoff would be
initialized to 0 (skb_network_offset) in init_flow_keys.
Now we call bpf_flow_dissect with nhoff set to ETH_HLEN and need
to undo it once the dissection is done to preserve the existing behavior.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 17 insertions, 30 deletions

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 006ad865f7fb..db2ec88ab129 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -379,12 +379,12 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
                                      union bpf_attr __user *uattr)
 {
         u32 size = kattr->test.data_size_in;
+        struct bpf_flow_dissector ctx = {};
         u32 repeat = kattr->test.repeat;
         struct bpf_flow_keys flow_keys;
         u64 time_start, time_spent = 0;
+        const struct ethhdr *eth;
         u32 retval, duration;
-        struct sk_buff *skb;
-        struct sock *sk;
         void *data;
         int ret;
         u32 i;
@@ -395,43 +395,31 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
         if (kattr->test.ctx_in || kattr->test.ctx_out)
                 return -EINVAL;
 
-        data = bpf_test_init(kattr, size, NET_SKB_PAD + NET_IP_ALIGN,
-                             SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
+        if (size < ETH_HLEN)
+                return -EINVAL;
+
+        data = bpf_test_init(kattr, size, 0, 0);
         if (IS_ERR(data))
                 return PTR_ERR(data);
 
-        sk = kzalloc(sizeof(*sk), GFP_USER);
-        if (!sk) {
-                kfree(data);
-                return -ENOMEM;
-        }
-        sock_net_set(sk, current->nsproxy->net_ns);
-        sock_init_data(NULL, sk);
-
-        skb = build_skb(data, 0);
-        if (!skb) {
-                kfree(data);
-                kfree(sk);
-                return -ENOMEM;
-        }
-        skb->sk = sk;
-
-        skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
-        __skb_put(skb, size);
-        skb->protocol = eth_type_trans(skb,
-                                       current->nsproxy->net_ns->loopback_dev);
-        skb_reset_network_header(skb);
+        eth = (struct ethhdr *)data;
 
         if (!repeat)
                 repeat = 1;
 
+        ctx.flow_keys = &flow_keys;
+        ctx.data = data;
+        ctx.data_end = (__u8 *)data + size;
+
         rcu_read_lock();
         preempt_disable();
         time_start = ktime_get_ns();
         for (i = 0; i < repeat; i++) {
-                retval = __skb_flow_bpf_dissect(prog, skb,
-                                                &flow_keys_dissector,
-                                                &flow_keys);
+                retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
+                                          size);
+
+                flow_keys.nhoff -= ETH_HLEN;
+                flow_keys.thoff -= ETH_HLEN;
 
                 if (signal_pending(current)) {
                         preempt_enable();
@@ -464,7 +452,6 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
                               retval, duration);
 
 out:
-        kfree_skb(skb);
-        kfree(sk);
+        kfree(data);
         return ret;
 }