Re: [PATCH bpf-next 1/2] bpf: add CHECKSUM_COMPLETE to bpf test progs

[Vadim Fedorenko <vadim.fedorenko@xxxxxxxxx>]

On 22/05/2024 19:32, Simon Horman wrote:
> On Wed, May 22, 2024 at 07:57:10AM -0700, Vadim Fedorenko wrote:
> > Add special flag to validate that TC BPF program properly updates
> > checksum information in skb.
> >
> > Signed-off-by: Vadim Fedorenko <vadfed@xxxxxxxx>
>
> ...
>
> > diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> > index f6aad4ed2ab2..841552785c65 100644
> > --- a/net/bpf/test_run.c
> > +++ b/net/bpf/test_run.c
> > @@ -974,10 +974,13 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> >   	int hh_len = ETH_HLEN;
> >   	struct sk_buff *skb;
> >   	struct sock *sk;
> > +	__wsum csum;
> > +	__sum16 sum;
>
> Hi Vadim,
>
> sum seems to be is unused in this function.
> And, fwiiw, the scope of csum looks like it could be reduced.

Ah, leftover from previous iteration, thanks for catching it!
Ok, I'll move csum to the "if" block in v2.

> >   	void *data;
> >   	int ret;
> >   
> > -	if (kattr->test.flags || kattr->test.cpu || kattr->test.batch_size)
> > +	if ((kattr->test.flags & ~BPF_F_TEST_SKB_CHECKSUM_COMPLETE) ||
> > +	    kattr->test.cpu || kattr->test.batch_size)
> >   		return -EINVAL;
> >   
> >   	data = bpf_test_init(kattr, kattr->test.data_size_in,
> > @@ -1025,6 +1028,12 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> >   
> >   	skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
> >   	__skb_put(skb, size);
> > +
> > +	if (kattr->test.flags & BPF_F_TEST_SKB_CHECKSUM_COMPLETE) {
> > +		skb->csum = skb_checksum(skb, 0, skb->len, 0);
> > +		skb->ip_summed = CHECKSUM_COMPLETE;
> > +	}
> > +
> >   	if (ctx && ctx->ifindex > 1) {
> >   		dev = dev_get_by_index(net, ctx->ifindex);
> >   		if (!dev) {
> > @@ -1079,6 +1088,14 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
> >   	}
> >   	convert_skb_to___skb(skb, ctx);
> >   
> > +	if (kattr->test.flags & BPF_F_TEST_SKB_CHECKSUM_COMPLETE) {
> > +		csum = skb_checksum(skb, 0, skb->len, 0);
> > +		if (skb->csum != csum) {
> > +			ret = -EINVAL;
> > +			goto out;
> > +		}
> > +	}
> > +
> >   	size = skb->len;
> >   	/* bpf program can never convert linear skb to non-linear */
> >   	if (WARN_ON_ONCE(skb_is_nonlinear(skb)))
>
> ...