linux-kernel - Re: [PATCH 4.4 24/72] audit: add tty field to LOGIN event

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Message-ID: <1526314736.9159.13.camel@codethink.co.uk>
Date:   Mon, 14 May 2018 17:18:56 +0100
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Cc:     stable@...r.kernel.org, Richard Guy Briggs <rgb@...hat.com>,
        Paul Moore <paul@...l-moore.com>
Subject: Re: [PATCH 4.4 24/72] audit: add tty field to LOGIN event

On Fri, 2018-04-06 at 15:23 +0200, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Richard Guy Briggs <rgb@...hat.com>
> 
> commit db0a6fb5d97afe01fd9c47d37c6daa82d4d4001d upstream.
[...]
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -1976,6 +1976,7 @@ static void audit_log_set_loginuid(kuid_
>  {
>  	struct audit_buffer *ab;
>  	uid_t uid, oldloginuid, loginuid;
> +	struct tty_struct *tty;
>  
>  	if (!audit_enabled)
>  		return;
> @@ -1983,14 +1984,17 @@ static void audit_log_set_loginuid(kuid_
>  	uid = from_kuid(&init_user_ns, task_uid(current));
>  	oldloginuid = from_kuid(&init_user_ns, koldloginuid);
>  	loginuid = from_kuid(&init_user_ns, kloginuid),
> +	tty = audit_get_tty(current);
>  
>  	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_LOGIN);
>  	if (!ab)
>  		return;

This error path leaks the tty ref.  Fixed upstream by:

commit 76a658c20efd541a62838d9ff68ce94170d7a549
Author: Richard Guy Briggs <rgb@...hat.com>
Date:   Tue Jun 28 12:06:58 2016 -0400

    audit: move calcs after alloc and check when logging set loginuid

Ben.

>  	audit_log_format(ab, "pid=%d uid=%u", task_pid_nr(current), uid);
>  	audit_log_task_context(ab);
> -	audit_log_format(ab, " old-auid=%u auid=%u old-ses=%u ses=%u res=%d",
> -			 oldloginuid, loginuid, oldsessionid, sessionid, !rc);
> +	audit_log_format(ab, " old-auid=%u auid=%u tty=%s old-ses=%u ses=%u res=%d",
> +			 oldloginuid, loginuid, tty ? tty_name(tty) : "(none)",
> +			 oldsessionid, sessionid, !rc);
> +	audit_put_tty(tty);
>  	audit_log_end(ab);
>  }
>  

-- 
Ben Hutchings
Software Developer, Codethink Ltd.