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

From: Vadim Fedorenko <[email-masked]>
Date: Fri, 27 Oct 2023 00:38:17 +0100

On 26.10.2023 23:53, Alexei Starovoitov wrote:
> On Wed, Oct 25, 2023 at 6:59 PM Vadim Fedorenko <[email-masked]> wrote:
>>
>> +__bpf_kfunc struct bpf_crypto_skcipher_ctx *
>> +bpf_crypto_skcipher_ctx_create(const struct bpf_dynptr_kern *algo, const struct bpf_dynptr_kern *key,
>> +                              int *err)
>> +{
>> +       struct bpf_crypto_skcipher_ctx *ctx;
>> +
>> +       if (__bpf_dynptr_size(algo) > CRYPTO_MAX_ALG_NAME) {
>> +               *err = -EINVAL;
>> +               return NULL;
>> +       }
>> +
>> +       if (!crypto_has_skcipher(algo->data, CRYPTO_ALG_TYPE_SKCIPHER, CRYPTO_ALG_TYPE_MASK)) {
>> +               *err = -EOPNOTSUPP;
>> +               return NULL;
>> +       }
>> +
>> +       ctx = bpf_mem_cache_alloc(&bpf_crypto_ctx_ma);
> 
> Since this kfunc is sleepable, just kmalloc(GFP_KERNEL) here.
> No need to use bpf_mem_alloc.

I was thinking about adding GFP_ATOMIC allocation option to
crypto_alloc_sync_skcipher, it's already implemented for cloning skcipher
object. Then the code can be reused for both sleepable (expect module loading)
and non-sleepable (fail if there is no crypto module loaded) variants without
any changes. But I can implement different allocators for different options.