Re: [PATCH v4 bpf-next 00/13] bpf: Enable bpf_skc_to_* sock casting helper to networking prog type

[Lorenz Bauer <lmb@cloudflare.com>]

On Fri, 25 Sep 2020 at 01:03, Martin KaFai Lau <kafai@fb.com> wrote:
>
> This set allows networking prog type to directly read fields from
> the in-kernel socket type, e.g. "struct tcp_sock".
>
> Patch 2 has the details on the use case.
>
> v3:
> - Pass arg_btf_id instead of fn into check_reg_type() in Patch 1 (Lorenz)
> - Move arg_btf_id from func_proto to struct bpf_reg_types in Patch 2 (Lorenz)
> - Remove test_sock_fields from .gitignore in Patch 8 (Andrii)
> - Add tests to have better coverage on the modified helpers (Alexei)
>   Patch 13 is added.
> - Use "void *sk" as the helper argument in UAPI bpf.h
>
> v3:
> - ARG_PTR_TO_SOCK_COMMON_OR_NULL was attempted in v2.  The _OR_NULL was
>   needed because the PTR_TO_BTF_ID could be NULL but note that a could be NULL
>   PTR_TO_BTF_ID is not a scalar NULL to the verifier.  "_OR_NULL" implicitly
>   gives an expectation that the helper can take a scalar NULL which does
>   not make sense in most (except one) helpers.  Passing scalar NULL
>   should be rejected at the verification time.
>
>   Thus, this patch uses ARG_PTR_TO_BTF_ID_SOCK_COMMON to specify that the
>   helper can take both the btf-id ptr or the legacy PTR_TO_SOCK_COMMON but
>   not scalar NULL.  It requires the func_proto to explicitly specify the
>   arg_btf_id such that there is a very clear expectation that the helper
>   can handle a NULL PTR_TO_BTF_ID.
>
> v2:
> - Add ARG_PTR_TO_SOCK_COMMON_OR_NULL (Lorenz)
>
> Martin KaFai Lau (13):
>   bpf: Move the PTR_TO_BTF_ID check to check_reg_type()
>   bpf: Enable bpf_skc_to_* sock casting helper to networking prog type
>   bpf: Change bpf_sk_release and bpf_sk_*cgroup_id to accept
>     ARG_PTR_TO_BTF_ID_SOCK_COMMON
>   bpf: Change bpf_sk_storage_*() to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON
>   bpf: Change bpf_tcp_*_syncookie to accept
>     ARG_PTR_TO_BTF_ID_SOCK_COMMON
>   bpf: Change bpf_sk_assign to accept ARG_PTR_TO_BTF_ID_SOCK_COMMON
>   bpf: selftest: Add ref_tracking verifier test for bpf_skc casting
>   bpf: selftest: Move sock_fields test into test_progs
>   bpf: selftest: Adapt sock_fields test to use skel and global variables
>   bpf: selftest: Use network_helpers in the sock_fields test
>   bpf: selftest: Use bpf_skc_to_tcp_sock() in the sock_fields test
>   bpf: selftest: Remove enum tcp_ca_state from bpf_tcp_helpers.h
>   bpf: selftest: Add test_btf_skc_cls_ingress


LGTM, thanks!

-- 
Lorenz Bauer  |  Systems Engineer
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