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Message-ID: <4258aabd-5f7b-4b7f-ab43-408b69bfdc58@linux.dev>
Date:   Thu, 2 Nov 2023 13:44:24 +0000
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Subject: Re: [PATCH bpf-next v3 1/2] bpf: add skcipher API support to TC/XDP
 programs
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To:     Martin KaFai Lau <martin.lau@linux.dev>, Song Liu <song@kernel.org>
Cc:     bpf@vger.kernel.org, netdev@vger.kernel.org,
        linux-crypto@vger.kernel.org, Jakub Kicinski <kuba@kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Mykola Lysenko <mykolal@fb.com>,
        Vadim Fedorenko <vadfed@meta.com>,
        "David S. Miller" <davem@davemloft.net>,
        Herbert Xu <herbert@gondor.apana.org.au>
References: <20231031134900.1432945-1-vadfed@meta.com>
 <dac97b74-5ff1-172b-9cd5-4cdcf07386ec@linux.dev>
 <91a6d5a7-7b18-48a2-9a74-7c00509467f8@linux.dev>
 <6947046d-27e3-90ee-3419-0b480af0abb0@linux.dev>
From:   Vadim Fedorenko <vadim.fedorenko@linux.dev>
In-Reply-To: <6947046d-27e3-90ee-3419-0b480af0abb0@linux.dev>
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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?