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Date:   Sat, 19 Sep 2020 10:01:43 +0200
From:   John Wood <john.wood@gmx.com>
To:     Kees Cook <keescook@chromium.org>
Cc:     John Wood <john.wood@gmx.com>, kernel-hardening@lists.openwall.com,
        Jann Horn <jannh@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Iurii Zaikin <yzaikin@google.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-security-module@vger.kernel.org
Subject: Re: [RFC PATCH 6/6] security/fbfam: Mitigate a fork brute force
 attack
Message-ID: <20200919080143.GA2998@ubuntu>
References: <20200910202107.3799376-1-keescook@chromium.org>
 <20200910202107.3799376-7-keescook@chromium.org>
 <202009101649.2A0BF95@keescook>
 <20200918152116.GB3229@ubuntu>
 <202009181433.EAF237C36@keescook>
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On Fri, Sep 18, 2020 at 02:35:12PM -0700, Kees Cook wrote:
> On Fri, Sep 18, 2020 at 06:02:16PM +0200, John Wood wrote:
> > On Thu, Sep 10, 2020 at 04:56:19PM -0700, Kees Cook wrote:
> > > On Thu, Sep 10, 2020 at 01:21:07PM -0700, Kees Cook wrote:
> > > > +		pr_warn("fbfam: Offending process with PID %d killed\n",
> > > > +			p->pid);
> > >
> > > I'd make this ratelimited (along with Jann's suggestions).
> >
> > Sorry, but I don't understand what you mean with "make this ratelimite=
d".
> > A clarification would be greatly appreciated.
>
> Ah! Yes, sorry for not being more clear. There are ratelimit helpers for
> the pr_*() family of functions, e.g.:
>
> 	pr_warn_ratelimited("brute: Offending process with PID...

Thanks for the clarification.

> --
> Kees Cook

Regards,
John Wood