netdev - Re: [PATCH net-next v2 04/12] net-timestamp: add static key to control the whole bpf extension

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: <CAL+tcoC5QLfpAuJrZxUPbaaK68pGKD31vuohi=NcXghe+uRpZA@mail.gmail.com>
Date: Wed, 16 Oct 2024 14:45:04 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, 
	pabeni@...hat.com, dsahern@...nel.org, willemdebruijn.kernel@...il.com, 
	willemb@...gle.com, ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org, bpf@...r.kernel.org, 
	netdev@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH net-next v2 04/12] net-timestamp: add static key to
 control the whole bpf extension

On Wed, Oct 16, 2024 at 2:31 PM Martin KaFai Lau <martin.lau@...ux.dev> wrote:
>
> On 10/15/24 6:04 PM, Jason Xing wrote:
> > To be honest, I considered how to disable the static key. Like you
> > said, I failed to find a good chance that I can accurately disable it.
>
> It at least needs to be disabled whenever that bpf prog got detached.
>
> >
> >> The bpf prog may be detached also. (IF) it ends up staying with the
> >> cgroup/sockops interface, it should depend on the existing static key in
> >> cgroup_bpf_enabled(CGROUP_SOCK_OPS) instead of adding another one.
>
> > Are you suggesting that we need to remove the current static key? In
> > the previous thread, the reason why Willem came up with this idea is,
> > I think, to avoid affect the non-bpf timestamping feature.
>
> Take a look at cgroup_bpf_enabled(CGROUP_SOCK_OPS). There is a static key. I am
> saying to use that existing key. afaict, the newly added bpf_tstamp_control key
> is mainly an optimization. Yes, cgroup_bpf_enabled(CGROUP_SOCK_OPS) is less
> granular but it has the needed accounting to disable whenever the bpf prog got
> detached, so better just reuse the cgroup_bpf_enabled(CGROUP_SOCK_OPS).

Good suggestion. Good thing is that I don't need to figure out a
proper place to disable it any more. I can directly use
cgroup_bpf_enabled(CGROUP_SOCK_OPS) to test if the timestamp should be
printed with BPF program loaded.

BTW, I found that we don't implement how to disable the ip4_min_ttl
static key. Sometimes, I'm confused whether we have to disable it at a
certain time.

Thanks,
Jason