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Subject: Re: [PATCH v3 3/8] securtiy/brute: Detect a brute force attack
To:     John Wood <john.wood@gmx.com>, Kees Cook <keescook@chromium.org>,
        Jann Horn <jannh@google.com>, Jonathan Corbet <corbet@lwn.net>,
        James Morris <jmorris@namei.org>, Shuah Khan <shuah@kernel.org>
Cc:     "Serge E. Hallyn" <serge@hallyn.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-kselftest@vger.kernel.org
References: <20210221154919.68050-1-john.wood@gmx.com>
 <20210221154919.68050-4-john.wood@gmx.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <085f8f05-243e-fbf0-3f9c-ea011511a296@infradead.org>
Date:   Sun, 21 Feb 2021 18:25:51 -0800
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Hi--

On 2/21/21 7:49 AM, John Wood wrote:
> 
> Signed-off-by: John Wood <john.wood@gmx.com>
> ---
>  security/brute/brute.c | 488 +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 474 insertions(+), 14 deletions(-)
> 
> diff --git a/security/brute/brute.c b/security/brute/brute.c
> index 70f812bb7763..645bd6e02638 100644
> --- a/security/brute/brute.c
> +++ b/security/brute/brute.c


> +/**
> + * print_fork_attack_running() - Warn about a fork brute force attack.
> + */
> +static inline void print_fork_attack_running(void)
> +{
> +	pr_warn("Fork brute force attack detected [%s]\n", current->comm);
> +}

Do these pr_warn() calls need to be rate-limited so that they don't
flood the kernel log?


> +/**
> + * print_exec_attack_running() - Warn about an exec brute force attack.
> + * @stats: Statistical data shared by all the fork hierarchy processes.
> + *
> + * The statistical data shared by all the fork hierarchy processes cannot be
> + * NULL.
> + *
> + * Before showing the process name it is mandatory to find a process that holds
> + * a pointer to the exec statistics.
> + *
> + * Context: Must be called with tasklist_lock and brute_stats_ptr_lock held.
> + */
> +static void print_exec_attack_running(const struct brute_stats *stats)
> +{
> +	struct task_struct *p;
> +	struct brute_stats **p_stats;
> +	bool found = false;
> +
> +	for_each_process(p) {
> +		p_stats = brute_stats_ptr(p);
> +		if (*p_stats == stats) {
> +			found = true;
> +			break;
> +		}
>  	}
> +
> +	if (WARN(!found, "No exec process\n"))
> +		return;
> +
> +	pr_warn("Exec brute force attack detected [%s]\n", p->comm);
> +}


thanks.
-- 
~Randy