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Date:   Mon, 21 Oct 2019 18:15:34 +0900
From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Sami Tolvanen <samitolvanen@google.com>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Dave Martin <Dave.Martin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Laura Abbott <labbott@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        clang-built-linux@googlegroups.com,
        kernel-hardening@lists.openwall.com,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 11/18] kprobes: disable kretprobes with SCS
Message-Id: <20191021181534.4d8edb330e6fb19cd7f7e39f@kernel.org>
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        <20191018161033.261971-12-samitolvanen@google.com>
        <20191018130429.5df61f6b@gandalf.local.home>
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On Fri, 18 Oct 2019 13:04:29 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> 
> [ Added Masami ]
> 
> On Fri, 18 Oct 2019 09:10:26 -0700
> Sami Tolvanen <samitolvanen@google.com> wrote:
> 
> > With CONFIG_KRETPROBES, function return addresses are modified to
> > redirect control flow to kretprobe_trampoline. This is incompatible with
> > return address protection.
> > 
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > ---
> >  arch/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index a222adda8130..4646e3b34925 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -171,7 +171,7 @@ config ARCH_USE_BUILTIN_BSWAP
> >  
> >  config KRETPROBES
> >  	def_bool y
> > -	depends on KPROBES && HAVE_KRETPROBES
> > +	depends on KPROBES && HAVE_KRETPROBES && ROP_PROTECTION_NONE
> 
> Again, this belongs in the arch code.

+1, below patch (from Steve) looks good to me.

Thank you,

> 
> -- Steve
> 
> >  
> >  config USER_RETURN_NOTIFIER
> >  	bool
> 
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 41a9b4257b72..65557d7e6b5e 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -166,7 +166,7 @@ config ARM64
>  	select HAVE_STACKPROTECTOR
>  	select HAVE_SYSCALL_TRACEPOINTS
>  	select HAVE_KPROBES
> -	select HAVE_KRETPROBES
> +	select HAVE_KRETPROBES if ROP_PROTECTION_NONE
>  	select HAVE_GENERIC_VDSO
>  	select IOMMU_DMA if IOMMU_SUPPORT
>  	select IRQ_DOMAIN


-- 
Masami Hiramatsu <mhiramat@kernel.org>