netdev - Re: [PATCH bpf-next v3 1/2] bpf: add skcipher API support to TC/XDP programs

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Message-ID: <CAADnVQ+9pp33zv9DxouEmg24o7w27OKFUcvKChHuby_+d6-bLg@mail.gmail.com>
Date: Thu, 2 Nov 2023 08:36:06 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>, bpf <bpf@...r.kernel.org>, 
	Network Development <netdev@...r.kernel.org>, 
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, Jakub Kicinski <kuba@...nel.org>, 
	Andrii Nakryiko <andrii@...nel.org>, Alexei Starovoitov <ast@...nel.org>, Mykola Lysenko <mykolal@...com>, 
	Vadim Fedorenko <vadfed@...a.com>, "David S. Miller" <davem@...emloft.net>, 
	Herbert Xu <herbert@...dor.apana.org.au>
Subject: Re: [PATCH bpf-next v3 1/2] bpf: add skcipher API support to TC/XDP programs

On Thu, Nov 2, 2023 at 6:44 AM Vadim Fedorenko
<vadim.fedorenko@...ux.dev> wrote:
>
> On 01/11/2023 23:41, Martin KaFai Lau wrote:
> > On 11/1/23 3:50 PM, Vadim Fedorenko wrote:
> >>>> +static void *__bpf_dynptr_data_ptr(const struct bpf_dynptr_kern *ptr)
> >>>> +{
> >>>> +    enum bpf_dynptr_type type;
> >>>> +
> >>>> +    if (!ptr->data)
> >>>> +        return NULL;
> >>>> +
> >>>> +    type = bpf_dynptr_get_type(ptr);
> >>>> +
> >>>> +    switch (type) {
> >>>> +    case BPF_DYNPTR_TYPE_LOCAL:
> >>>> +    case BPF_DYNPTR_TYPE_RINGBUF:
> >>>> +        return ptr->data + ptr->offset;
> >>>> +    case BPF_DYNPTR_TYPE_SKB:
> >>>> +        return skb_pointer_if_linear(ptr->data, ptr->offset,
> >>>> __bpf_dynptr_size(ptr));
> >>>> +    case BPF_DYNPTR_TYPE_XDP:
> >>>> +    {
> >>>> +        void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset,
> >>>> __bpf_dynptr_size(ptr));
> >>>
> >>> I suspect what it is doing here (for skb and xdp in particular) is
> >>> very similar to bpf_dynptr_slice. Please check if
> >>> bpf_dynptr_slice(ptr, 0, NULL, sz) will work.
> >>>
> >>
> >> Well, yes, it's simplified version of bpf_dynptr_slice. The problem is
> >> that bpf_dynptr_slice bpf_kfunc which cannot be used in another
> >> bpf_kfunc. Should I refactor the code to use it in both places? Like
> >
> > Sorry, scrolled too fast in my earlier reply :(
> >
> > I am not aware of this limitation. What error does it have?
> > The bpf_dynptr_slice_rdwr kfunc() is also calling the bpf_dynptr_slice()
> > kfunc.
> >
> >> create __bpf_dynptr_slice() which will be internal part of bpf_kfunc?
>
> Apparently Song has a patch to expose these bpf_dynptr_slice* functions
> ton in-kernel users.
>
> https://lore.kernel.org/bpf/20231024235551.2769174-2-song@kernel.org/
>
> Should I wait for it to be merged before sending next version?

If you need something from another developer it's best to ask them
explicitly :)
In this case Song can respin with just that change that you need.