linux-kernel - Re: [patch part-II V2 01/13] context_tracking: Ensure that the critical path cannot be instrumented

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 for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200309142223.GD9615@lenoir>
Date:   Mon, 9 Mar 2020 15:22:24 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>
Subject: Re: [patch part-II V2 01/13] context_tracking: Ensure that the
 critical path cannot be instrumented

On Sun, Mar 08, 2020 at 11:24:00PM +0100, Thomas Gleixner wrote:
> context tracking lacks a few protection mechanisms against instrumentation:
> 
>  - While the core functions are marked NOKPROBE they lack protection
>    against function tracing which is required as the function entry/exit
>    points can be utilized by BPF.

Just to clarify things up: IIUC, BPF scripts can be called from the
function graph tracer hooks, and that BPF code uses RCU, right?

> 
>  - static functions invoked from the protected functions need to be marked
>    as well as they can be instrumented otherwise.
> 
>  - using plain inline allows the compiler to emit traceable and probable
>    functions.
> 
> Fix this by adding the missing notrace/NOKPROBE annotations and converting
> the plain inlines to __always_inline.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Acked-by: Frederic Weisbecker <frederic@...nel.org>