netdev - Re: [PATCH v2 bpf-next 3/4] bpf: Allow using bpf_sk_storage in FENTRY/FEXIT/RAW

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: <20201116173734.a5efp2rvg43762ut@kafai-mbp.dhcp.thefacebook.com>
Date:   Mon, 16 Nov 2020 09:37:34 -0800
From:   Martin KaFai Lau <kafai@...com>
To:     Jakub Kicinski <kuba@...nel.org>
CC:     <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        <netdev@...r.kernel.org>, Song Liu <songliubraving@...com>
Subject: Re: [PATCH v2 bpf-next 3/4] bpf: Allow using bpf_sk_storage in
 FENTRY/FEXIT/RAW_TP

On Sat, Nov 14, 2020 at 05:17:20PM -0800, Jakub Kicinski wrote:
> On Thu, 12 Nov 2020 13:13:13 -0800 Martin KaFai Lau wrote:
> > This patch adds bpf_sk_storage_get_tracing_proto and
> > bpf_sk_storage_delete_tracing_proto.  They will check
> > in runtime that the helpers can only be called when serving
> > softirq or running in a task context.  That should enable
> > most common tracing use cases on sk.
> 
> > +	if (!in_serving_softirq() && !in_task())
> 
> This is a curious combination of checks. Would you mind indulging me
> with an explanation?
The current lock usage in bpf_local_storage.c is only expected to
run in either of these contexts.