linux-kernel - Re: [RFC PATCH] panic: Add new taint flag for fault injection

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Message-ID: <20221201162526.2fdfd65d@gandalf.local.home>
Date:   Thu, 1 Dec 2022 16:25:26 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Chris Mason <clm@...a.com>
Cc:     Kees Cook <keescook@...omium.org>,
        "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        KP Singh <kpsingh@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Florent Revest <revest@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [RFC PATCH] panic: Add new taint flag for fault injection

On Thu, 1 Dec 2022 16:00:03 -0500
Chris Mason <clm@...a.com> wrote:

> On 12/1/22 2:14 PM, Steven Rostedt wrote:
> > On Thu, 1 Dec 2022 08:53:02 -0800
> > Kees Cook <keescook@...omium.org> wrote:
> >   
> >>> Have you not been reading this thread?    
> >>
> >> I skimmed it -- trying to catch up from turkey week. If this was already
> >> covered, then please ignore me. It just wasn't obvious from the commit
> >> log why it was included.  
> > 
> > That's a better request :-)
> > 
> > That is, please add why this is needed for BPF (and also include a Link:
> > tag to this thread).  
> 
> Sorry, I'm completely failing to parse.  Is this directed at Kees or
> Benjamin?  I'm also not sure what the this is in "why this is needed for
> BPF"?
> 

It was directed towards Kees. I don't even know who "Benjamin" is. I don't
see a "Benjamin" in the Cc list.

And "this" is for:

--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2137,6 +2137,8 @@ int perf_event_attach_bpf_prog(struct perf_event *event,
 		goto unlock;
 
 	/* set the new array to event->tp_event and set event->prog */
+	if (prog->kprobe_override)
+		add_taint(TAINT_FAULT_INJECTED, LOCKDEP_NOW_UNRELIABLE);
 	event->prog = prog;
 	event->bpf_cookie = bpf_cookie;
 	rcu_assign_pointer(event->tp_event->prog_array, new_array);

-- Steve