linux-kernel - Re: [PATCH bpf-next] bpf: Support default .validate() and .update() behavior for struct

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]

Date:   Thu, 10 Aug 2023 15:46:18 -0700
From:   Stanislav Fomichev <sdf@...gle.com>
To:     David Vernet <void@...ifault.com>
Cc:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org,
        yhs@...com, john.fastabend@...il.com, kpsingh@...nel.org,
        haoluo@...gle.com, jolsa@...nel.org, linux-kernel@...r.kernel.org,
        kernel-team@...a.com, tj@...nel.org, clm@...a.com,
        thinker.li@...il.com
Subject: Re: [PATCH bpf-next] bpf: Support default .validate() and .update()
 behavior for struct_ops links

On 08/10, David Vernet wrote:
> Currently, if a struct_ops map is loaded with BPF_F_LINK, it must also
> define the .validate() and .update() callbacks in its corresponding
> struct bpf_struct_ops in the kernel. Enabling struct_ops link is useful
> in its own right to ensure that the map is unloaded if an application
> crashes. For example, with sched_ext, we want to automatically unload
> the host-wide scheduler if the application crashes. We would likely
> never support updating elements of a sched_ext struct_ops map, so we'd
> have to implement these callbacks showing that they _can't_ support
> element updates just to benefit from the basic lifetime management of
> struct_ops links.
> 
> Let's enable struct_ops maps to work with BPF_F_LINK even if they
> haven't defined these callbacks, by assuming that a struct_ops map
> element cannot be updated by default.

Any reason this is not part of sched_ext series? As you mention,
we don't seem to have such users in the three?