netdev - Re: [PATCH bpf-next v4 1/3] bpf: support input __sk_buff context in BPF_PROG_TEST

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Date:   Thu, 11 Apr 2019 10:04:59 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Stanislav Fomichev <sdf@...gle.com>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     davem@...emloft.net, ast@...nel.org, Martin Lau <kafai@...com>
Subject: Re: [PATCH bpf-next v4 1/3] bpf: support input __sk_buff context in
 BPF_PROG_TEST_RUN

On 04/09/2019 08:49 PM, Stanislav Fomichev wrote:
> Add new set of arguments to bpf_attr for BPF_PROG_TEST_RUN:
> * ctx_in/ctx_size_in - input context
> * ctx_out/ctx_size_out - output context
> 
> The intended use case is to pass some meta data to the test runs that
> operate on skb (this has being brought up on recent LPC).
> 
> For programs that use bpf_prog_test_run_skb, support __sk_buff input and
> output. Initially, from input __sk_buff, copy _only_ cb and priority into
> skb, all other non-zero fields are prohibited (with EINVAL).
> If the user has set ctx_out/ctx_size_out, copy the potentially modified
> __sk_buff back to the userspace.
> 
> We require all fields of input __sk_buff except the ones we explicitly
> support to be set to zero. The expectation is that in the future we might
> add support for more fields and we want to fail explicitly if the user
> runs the program on the kernel where we don't yet support them.
> 
> The API is intentionally vague (i.e. we don't explicitly add __sk_buff
> to bpf_attr, but ctx_in) to potentially let other test_run types use
> this interface in the future (this can be xdp_md for xdp types for
> example).
> 
> v4:
>   * don't copy more than allowed in bpf_ctx_init [Martin]
> 
> v3:
>   * handle case where ctx_in is NULL, but ctx_out is not [Martin]
>   * convert size==0 checks to ptr==NULL checks and add some extra ptr
>     checks [Martin]
> 
> v2:
>   * Addressed comments from Martin Lau
> 
> Cc: Martin Lau <kafai@...com>
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>

Series applied, thanks!