On Fri, Feb 21, 2020 at 10:47 AM Martin KaFai Lau <kafai@xxxxxx> wrote:
>
> This patch adds INET_DIAG support to bpf_sk_storage.
>
> 1. Although this series adds bpf_sk_storage diag capability to inet sk,
> bpf_sk_storage is in general applicable to all fullsock. Hence, the
> bpf_sk_storage logic will operate on SK_DIAG_* nlattr. The caller
> will pass in its specific nesting nlattr (e.g. INET_DIAG_*) as
> the argument.
>
> 2. The request will be like:
> INET_DIAG_REQ_SK_BPF_STORAGES (nla_nest) (defined in latter patch)
> SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
> SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
> ......
>
> Considering there could have multiple bpf_sk_storages in a sk,
> instead of reusing INET_DIAG_INFO ("ss -i"), the user can select
> some specific bpf_sk_storage to dump by specifying an array of
> SK_DIAG_BPF_STORAGE_REQ_MAP_FD.
>
> If no SK_DIAG_BPF_STORAGE_REQ_MAP_FD is specified (i.e. an empty
> INET_DIAG_REQ_SK_BPF_STORAGES), it will dump all bpf_sk_storages
> of a sk.
>
> 3. The reply will be like:
> INET_DIAG_BPF_SK_STORAGES (nla_nest) (defined in latter patch)
> SK_DIAG_BPF_STORAGE (nla_nest)
> SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
> SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
> SK_DIAG_BPF_STORAGE (nla_nest)
> SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
> SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
> ......
>
> 4. Unlike other INET_DIAG info of a sk which is pretty static, the size
> required to dump the bpf_sk_storage(s) of a sk is dynamic as the
> system adding more bpf_sk_storage_map. It is hard to set a static
> min_dump_alloc size.
>
> Hence, this series learns it at the runtime and adjust the
> cb->min_dump_alloc as it iterates all sk(s) of a system. The
> "unsigned int *res_diag_size" in bpf_sk_storage_diag_put()
> is for this purpose.
>
> The next patch will update the cb->min_dump_alloc as it
> iterates the sk(s).
>
> Signed-off-by: Martin KaFai Lau <kafai@xxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
