Nick Hudson wrote:
> Require BPF_F_ADJ_ROOM_DECAP_L4_UDP and BPF_F_ADJ_ROOM_DECAP_L4_GRE enum
> values at runtime using CO-RE enum existence checks so missing kernel
> support fails fast instead of silently proceeding.
>
> After bpf_skb_adjust_room() decapsulation, inspect skb_shared_info and
> sk_buff state for GSO packets and assert that the expected tunnel GSO
> bits are cleared and encapsulation matches the remaining tunnel state.
>
> Signed-off-by: Nick Hudson <[email protected]>
> ---
> .../selftests/bpf/progs/test_tc_tunnel.c | 58 +++++++++++++++++++
> 1 file changed, 58 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> index 7376df405a6b..74dfb694a210 100644
> --- a/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> +++ b/tools/testing/selftests/bpf/progs/test_tc_tunnel.c
> @@ -6,6 +6,7 @@
>
> #include <bpf/bpf_helpers.h>
> #include <bpf/bpf_endian.h>
> +#include <bpf/bpf_core_read.h>
> #include "bpf_tracing_net.h"
> #include "bpf_compiler.h"
>
> @@ -37,6 +38,23 @@ struct vxlanhdr___local {
>
> #define EXTPROTO_VXLAN 0x1
>
> +#define SKB_GSO_UDP_TUNNEL_MASK (SKB_GSO_UDP_TUNNEL |
> \
> + SKB_GSO_UDP_TUNNEL_CSUM | \
> + SKB_GSO_TUNNEL_REMCSUM)
Leftover remcsum reference?
> +
> +#define SKB_GSO_TUNNEL_MASK (SKB_GSO_UDP_TUNNEL_MASK |
> \
Odd indentation?
> + SKB_GSO_GRE | \
> + SKB_GSO_GRE_CSUM | \
> + SKB_GSO_IPXIP4 | \
> + SKB_GSO_IPXIP6 | \
> + SKB_GSO_ESP)
> +
> +#define BPF_F_ADJ_ROOM_DECAP_L4_MASK (BPF_F_ADJ_ROOM_DECAP_L4_UDP | \
> + BPF_F_ADJ_ROOM_DECAP_L4_GRE)
> +
> +#define BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK (BPF_F_ADJ_ROOM_DECAP_IPXIP4 |
> \
> + BPF_F_ADJ_ROOM_DECAP_IPXIP6)
> +
> #define VXLAN_FLAGS bpf_htonl(1<<27)
> #define VNI_ID 1
> #define VXLAN_VNI bpf_htonl(VNI_ID << 8)
> @@ -592,6 +610,8 @@ int __encap_ip6vxlan_eth(struct __sk_buff *skb)
> static int decap_internal(struct __sk_buff *skb, int off, int len, char
> proto)
> {
> __u64 flags = BPF_F_ADJ_ROOM_FIXED_GSO;
> + struct sk_buff *kskb;
> + struct skb_shared_info *shinfo;
> struct ipv6_opt_hdr ip6_opt_hdr;
> struct gre_hdr greh;
> struct udphdr udph;
> @@ -621,6 +641,11 @@ static int decap_internal(struct __sk_buff *skb, int
> off, int len, char proto)
> break;
> case IPPROTO_GRE:
> olen += sizeof(struct gre_hdr);
> + if (!bpf_core_enum_value_exists(enum bpf_adj_room_flags,
> + BPF_F_ADJ_ROOM_DECAP_L4_GRE))
> + return TC_ACT_SHOT;
> + flags |= BPF_F_ADJ_ROOM_DECAP_L4_GRE;
> +
> if (bpf_skb_load_bytes(skb, off + len, &greh, sizeof(greh)) < 0)
> return TC_ACT_OK;
> switch (bpf_ntohs(greh.protocol)) {
> @@ -634,6 +659,10 @@ static int decap_internal(struct __sk_buff *skb, int
> off, int len, char proto)
> break;
> case IPPROTO_UDP:
> olen += sizeof(struct udphdr);
> + if (!bpf_core_enum_value_exists(enum bpf_adj_room_flags,
> + BPF_F_ADJ_ROOM_DECAP_L4_UDP))
> + return TC_ACT_SHOT;
> + flags |= BPF_F_ADJ_ROOM_DECAP_L4_UDP;
> if (bpf_skb_load_bytes(skb, off + len, &udph, sizeof(udph)) < 0)
> return TC_ACT_OK;
> switch (bpf_ntohs(udph.dest)) {
> @@ -655,6 +684,35 @@ static int decap_internal(struct __sk_buff *skb, int
> off, int len, char proto)
> if (bpf_skb_adjust_room(skb, -olen, BPF_ADJ_ROOM_MAC, flags))
> return TC_ACT_SHOT;
>
> + kskb = bpf_cast_to_kern_ctx(skb);
> + shinfo = bpf_core_cast(kskb->head + kskb->end, struct skb_shared_info);
> + if (!shinfo->gso_size)
> + return TC_ACT_OK;
> +
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_UDP) &&
> + (shinfo->gso_type & SKB_GSO_UDP_TUNNEL_MASK))
> + return TC_ACT_SHOT;
> +
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_L4_GRE) &&
> + (shinfo->gso_type & (SKB_GSO_GRE | SKB_GSO_GRE_CSUM)))
> + return TC_ACT_SHOT;
> +
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP4) &&
> + (shinfo->gso_type & SKB_GSO_IPXIP4))
> + return TC_ACT_SHOT;
> +
> + if ((flags & BPF_F_ADJ_ROOM_DECAP_IPXIP6) &&
> + (shinfo->gso_type & SKB_GSO_IPXIP6))
> + return TC_ACT_SHOT;
> +
> + if (flags & (BPF_F_ADJ_ROOM_DECAP_L4_MASK |
> + BPF_F_ADJ_ROOM_DECAP_IPXIP_MASK)) {
> + if ((shinfo->gso_type & SKB_GSO_TUNNEL_MASK) &&
> !kskb->encapsulation)
> + return TC_ACT_SHOT;
> + if (!(shinfo->gso_type & SKB_GSO_TUNNEL_MASK) &&
> kskb->encapsulation)
> + return TC_ACT_SHOT;
> + }
> +
> return TC_ACT_OK;
> }
>
> --
> 2.34.1
>
