On Mon, Jul 1, 2019 at 8:31 AM John Hurley <john.hur...@netronome.com> wrote:
>
> Currently, TC offers the ability to match on the MPLS fields of a packet
> through the use of the flow_dissector_key_mpls struct. However, as yet, TC
> actions do not allow the modification or manipulation of such fields.
>
> Add a new module that registers TC action ops to allow manipulation of
> MPLS. This includes the ability to push and pop headers as well as modify
> the contents of new or existing headers. A further action to decrement the
> TTL field of an MPLS header is also provided.
>
> Signed-off-by: John Hurley <john.hur...@netronome.com>
> Reviewed-by: Jakub Kicinski <jakub.kicin...@netronome.com>
> Reviewed-by: Simon Horman <simon.hor...@netronome.com>
> +static __be32 tcf_mpls_get_lse(struct mpls_shim_hdr *lse,
> + struct tcf_mpls_params *p, bool set_bos)
> +{
> + u32 new_lse = 0;
> +
> + if (lse)
> + new_lse = be32_to_cpu(lse->label_stack_entry);
> +
> + if (p->tcfm_label) {
> + new_lse &= ~MPLS_LS_LABEL_MASK;
> + new_lse |= p->tcfm_label << MPLS_LS_LABEL_SHIFT;
> + }
> + if (p->tcfm_ttl) {
> + new_lse &= ~MPLS_LS_TTL_MASK;
> + new_lse |= p->tcfm_ttl << MPLS_LS_TTL_SHIFT;
> + }
> + if (p->tcfm_tc != ACT_MPLS_TC_NOT_SET) {
> + new_lse &= ~MPLS_LS_TC_MASK;
> + new_lse |= p->tcfm_tc << MPLS_LS_TC_SHIFT;
> + }
> + if (p->tcfm_bos != ACT_MPLS_BOS_NOT_SET) {
> + new_lse &= ~MPLS_LS_S_MASK;
> + new_lse |= p->tcfm_bos << MPLS_LS_S_SHIFT;
> + } else if (set_bos) {
> + new_lse |= 1 << MPLS_LS_S_SHIFT;
> + }
not necessarily for this patchset, but perhaps it would make code more
readable to add a struct mpls_label_type with integer bit fields to avoid
all this explicit masking and shifting.
> +static int tcf_mpls_act(struct sk_buff *skb, const struct tc_action *a,
> + struct tcf_result *res)
> +{
> + struct tcf_mpls *m = to_mpls(a);
> + struct mpls_shim_hdr *pkt_lse;
> + struct tcf_mpls_params *p;
> + __be32 new_lse;
> + u32 cpu_lse;
> + int ret;
> + u8 ttl;
> +
> + tcf_lastuse_update(&m->tcf_tm);
> + bstats_cpu_update(this_cpu_ptr(m->common.cpu_bstats), skb);
> +
> + /* Ensure 'data' points at mac_header prior calling mpls manipulating
> + * functions.
> + */
> + if (skb_at_tc_ingress(skb))
> + skb_push_rcsum(skb, skb->mac_len);
> +
> + ret = READ_ONCE(m->tcf_action);
> +
> + p = rcu_dereference_bh(m->mpls_p);
> +
> + switch (p->tcfm_action) {
> + case TCA_MPLS_ACT_POP:
> + if (skb_mpls_pop(skb, p->tcfm_proto))
> + goto drop;
> + break;
> + case TCA_MPLS_ACT_PUSH:
> + new_lse = tcf_mpls_get_lse(NULL, p,
> !eth_p_mpls(skb->protocol));
> + if (skb_mpls_push(skb, new_lse, p->tcfm_proto))
> + goto drop;
> + break;
> + case TCA_MPLS_ACT_MODIFY:
> + new_lse = tcf_mpls_get_lse(mpls_hdr(skb), p, false);
> + if (skb_mpls_update_lse(skb, new_lse))
> + goto drop;
> + break;
> + case TCA_MPLS_ACT_DEC_TTL:
> + pkt_lse = mpls_hdr(skb);
> + cpu_lse = be32_to_cpu(pkt_lse->label_stack_entry);
> + ttl = (cpu_lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
> + if (!--ttl)
> + goto drop;
> +
> + cpu_lse &= ~MPLS_LS_TTL_MASK;
> + cpu_lse |= ttl << MPLS_LS_TTL_SHIFT;
this could perhaps use a helper of its own?
> + if (skb_mpls_update_lse(skb, cpu_to_be32(cpu_lse)))
> + goto drop;
> + break;
> + }
