Re: [PATCH] selftests_bpf: extend test_tc_tunnel test with vxlan

[Xuesen Huang <hxseverything@gmail.com>]

> 2021年3月4日 下午10:02，Willem de Bruijn <willemdebruijn.kernel@gmail.com> 写道：
> 
> On Thu, Mar 4, 2021 at 1:42 AM Xuesen Huang <hxseverything@gmail.com> wrote:
>> 
>> From: Xuesen Huang <huangxuesen@kuaishou.com>
>> 
>> Add BPF_F_ADJ_ROOM_ENCAP_L2_ETH flag to the existing tests which
>> encapsulates the ethernet as the inner l2 header.
>> 
>> Update a vxlan encapsulation test case.
>> 
>> Signed-off-by: Xuesen Huang <huangxuesen@kuaishou.com>
>> Signed-off-by: Li Wang <wangli09@kuaishou.com>
>> Signed-off-by: Willem de Bruijn <willemb@google.com>
> 
> Please mark patch target: [PATCH bpf-next]
> 
Thanks.

>> ---
>> tools/testing/selftests/bpf/progs/test_tc_tunnel.c | 113 ++++++++++++++++++---
>> tools/testing/selftests/bpf/test_tc_tunnel.sh      |  15 ++-
>> 2 files changed, 111 insertions(+), 17 deletions(-)
> 
> 
>> -static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
>> -                                     __u16 l2_proto)
>> +static __always_inline int __encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
>> +                                       __u16 l2_proto, __u16 ext_proto)
>> {
>>        __u16 udp_dst = UDP_PORT;
>>        struct iphdr iph_inner;
>>        struct v4hdr h_outer;
>>        struct tcphdr tcph;
>>        int olen, l2_len;
>> +       __u8 *l2_hdr = NULL;
>>        int tcp_off;
>>        __u64 flags;
>> 
>> @@ -141,7 +157,11 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
>>                break;
>>        case ETH_P_TEB:
>>                l2_len = ETH_HLEN;
>> -               udp_dst = ETH_OVER_UDP_PORT;
>> +               if (ext_proto & EXTPROTO_VXLAN) {
>> +                       udp_dst = VXLAN_UDP_PORT;
>> +                       l2_len += sizeof(struct vxlanhdr);
>> +               } else
>> +                       udp_dst = ETH_OVER_UDP_PORT;
>>                break;
>>        }
>>        flags |= BPF_F_ADJ_ROOM_ENCAP_L2(l2_len);
>> @@ -171,14 +191,26 @@ static __always_inline int encap_ipv4(struct __sk_buff *skb, __u8 encap_proto,
>>        }
>> 
>>        /* add L2 encap (if specified) */
>> +       l2_hdr = (__u8 *)&h_outer + olen;
>>        switch (l2_proto) {
>>        case ETH_P_MPLS_UC:
>> -               *((__u32 *)((__u8 *)&h_outer + olen)) = mpls_label;
>> +               *(__u32 *)l2_hdr = mpls_label;
>>                break;
>>        case ETH_P_TEB:
>> -               if (bpf_skb_load_bytes(skb, 0, (__u8 *)&h_outer + olen,
>> -                                      ETH_HLEN))
>> +               flags |= BPF_F_ADJ_ROOM_ENCAP_L2_ETH;
>> +
>> +               if (ext_proto & EXTPROTO_VXLAN) {
>> +                       struct vxlanhdr *vxlan_hdr = (struct vxlanhdr *)l2_hdr;
>> +
>> +                       vxlan_hdr->vx_flags = VXLAN_FLAGS;
>> +                       vxlan_hdr->vx_vni = bpf_htonl((VXLAN_VNI & VXLAN_VNI_MASK) << 8);
>> +
>> +                       l2_hdr += sizeof(struct vxlanhdr);
> 
> should this be l2_len? (here and ipv6 below)
> 
Should be l2_hdr. 

It’s a little tricky. l2_len has already been modified above. We use l2_hdr here 
to help us to find the address in h_outer to load original Ethernet header which 
is different in (eth) and (vxlan + eth).

>> +SEC("encap_vxlan_eth")
>> +int __encap_vxlan_eth(struct __sk_buff *skb)
>> +{
>> +       if (skb->protocol == __bpf_constant_htons(ETH_P_IP))
>> +               return __encap_ipv4(skb, IPPROTO_UDP,
>> +                               ETH_P_TEB,
>> +                               EXTPROTO_VXLAN);
> 
> non-standard indentation: align with the opening parenthesis. (here
> and ipv6 below)
Thanks.