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Date:   Thu, 1 Dec 2022 16:25:26 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Chris Mason <clm@meta.com>
Cc:     Kees Cook <keescook@chromium.org>,
        "Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        KP Singh <kpsingh@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Florent Revest <revest@chromium.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC PATCH] panic: Add new taint flag for fault injection
Message-ID: <20221201162526.2fdfd65d@gandalf.local.home>
In-Reply-To: <78b7a67f-8c5b-6b2e-7fb5-01c47d75c104@meta.com>
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        <202212010838.B0B109DA@keescook>
        <20221201114848.13a87aca@gandalf.local.home>
        <202212010852.6D4B542@keescook>
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        <78b7a67f-8c5b-6b2e-7fb5-01c47d75c104@meta.com>
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On Thu, 1 Dec 2022 16:00:03 -0500
Chris Mason <clm@meta.com> wrote:

> On 12/1/22 2:14 PM, Steven Rostedt wrote:
> > On Thu, 1 Dec 2022 08:53:02 -0800
> > Kees Cook <keescook@chromium.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