netdev - Re: [PATCH bpf-next 1/5] bpf: add support for forced LINK

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <E5C327CB-962D-46B9-9816-29169F62C4EF@fb.com>
Date:   Thu, 30 Jul 2020 17:43:22 +0000
From:   Song Liu <songliubraving@...com>
To:     Andrii Nakryiko <andriin@...com>
CC:     bpf <bpf@...r.kernel.org>, Netdev <netdev@...r.kernel.org>,
        "Alexei Starovoitov" <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        "Andrii Nakryiko" <andrii.nakryiko@...il.com>,
        Kernel Team <Kernel-team@...com>,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH bpf-next 1/5] bpf: add support for forced LINK_DETACH
 command



> On Jul 29, 2020, at 4:05 PM, Andrii Nakryiko <andriin@...com> wrote:
> 
> Add LINK_DETACH command to force-detach bpf_link without destroying it. It has
> the same behavior as auto-detaching of bpf_link due to cgroup dying for
> bpf_cgroup_link or net_device being destroyed for bpf_xdp_link. In such case,
> bpf_link is still a valid kernel object, but is defuncts and doesn't hold BPF
> program attached to corresponding BPF hook. This functionality allows users
> with enough access rights to manually force-detach attached bpf_link without
> killing respective owner process.
> 
> This patch implements LINK_DETACH for cgroup, xdp, and netns links, mostly
> re-using existing link release handling code.
> 
> Signed-off-by: Andrii Nakryiko <andriin@...com>

The code looks good to me. My only question is, do we need both 
bpf_link_ops->detach and bpf_link_ops->release? 

Thanks,
Song

[...]