selftests/bpf: convert bpf tunnel test to BPF_ADJ_ROOM_MAC

Avoid moving the network layer header when prefixing tunnel headers.

This avoids an explicit call to bpf_skb_store_bytes and an implicit
move of the network header bytes in bpf_skb_adjust_room.

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
index 900c565..f6a16fd 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
@@ -72,7 +72,7 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
        olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
        /* add room between mac and network header */
-       if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
+       if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
                return TC_ACT_SHOT;
 
        /* prepare new outer network header */
@@ -94,12 +94,6 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, bool with_gre)
                                BPF_F_INVALIDATE_HASH) < 0)
                return TC_ACT_SHOT;
 
-       /* bpf_skb_adjust_room has moved header to start of room: restore */
-       if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
-                               &iph_inner, sizeof(iph_inner),
-                               BPF_F_INVALIDATE_HASH) < 0)
-               return TC_ACT_SHOT;
-
        return TC_ACT_OK;
 }
 
@@ -125,7 +119,7 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
        olen = with_gre ? sizeof(h_outer) : sizeof(h_outer.ip);
 
        /* add room between mac and network header */
-       if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_NET, 0))
+       if (bpf_skb_adjust_room(skb, olen, BPF_ADJ_ROOM_MAC, 0))
                return TC_ACT_SHOT;
 
        /* prepare new outer network header */
@@ -145,12 +139,6 @@ static __always_inline int encap_ipv6(struct __sk_buff *skb, bool with_gre)
                                BPF_F_INVALIDATE_HASH) < 0)
                return TC_ACT_SHOT;
 
-       /* bpf_skb_adjust_room has moved header to start of room: restore */
-       if (bpf_skb_store_bytes(skb, ETH_HLEN + olen,
-                               &iph_inner, sizeof(iph_inner),
-                               BPF_F_INVALIDATE_HASH) < 0)
-               return TC_ACT_SHOT;
-
        return TC_ACT_OK;
 }
 
@@ -207,14 +195,7 @@ static int decap_internal(struct __sk_buff *skb, int off, int len, char proto)
                return TC_ACT_OK;
        }
 
-       if (bpf_skb_load_bytes(skb, off + olen, &buf, olen) < 0)
-               return TC_ACT_OK;
-
-       if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_NET, 0))
-               return TC_ACT_SHOT;
-
-       /* bpf_skb_adjust_room has moved outer over inner header: restore */
-       if (bpf_skb_store_bytes(skb, off, buf, len, BPF_F_INVALIDATE_HASH) < 0)
+       if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC, 0))
                return TC_ACT_SHOT;
 
        return TC_ACT_OK;