[PATCH v17 07/12] bpf: Add bpf_verify_pkcs7_signature() kfunc

[Song Liu]

On Fri, Sep 9, 2022 at 1:09 PM Roberto Sassu
<roberto.sassu at huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu at huawei.com>
>
> Add the bpf_verify_pkcs7_signature() kfunc, to give eBPF security modules
> the ability to check the validity of a signature against supplied data, by
> using user-provided or system-provided keys as trust anchor.
>
> The new kfunc makes it possible to enforce mandatory policies, as eBPF
> programs might be allowed to make security decisions only based on data
> sources the system administrator approves.
>
> The caller should provide the data to be verified and the signature as eBPF
> dynamic pointers (to minimize the number of parameters) and a bpf_key
> structure containing a reference to the keyring with keys trusted for
> signature verification, obtained from bpf_lookup_user_key() or
> bpf_lookup_system_key().
>
> For bpf_key structures obtained from the former lookup function,
> bpf_verify_pkcs7_signature() completes the permission check deferred by
> that function by calling key_validate(). key_task_permission() is already
> called by the PKCS#7 code.
>
> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>
> Acked-by: KP Singh <kpsingh at kernel.org>

Acked-by: Song Liu <song at kernel.org>

[...]