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

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Message-ID: <c4e6296d-f273-4b27-a33a-eee5c8f54aab@linux.dev>
Date: Thu, 2 Nov 2023 16:14:38 +0000
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
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 02/11/2023 15:36, Alexei Starovoitov wrote:
> 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.

Got it. I actually need 2 different changes from the same patchset, I'll 
ping Song in the appropriate thread, thanks!