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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Will Deacon <will@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@android.com,
	akpm@linux-foundation.org,
	"K . Prasad" <prasad@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Frederic Weisbecker <frederic@kernel.org>,
	Christoph Hellwig <hch@lst.de>,
	Quentin Perret <qperret@google.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 3/3] kallsyms: Unexport kallsyms_lookup_name() and kallsyms_on_each_symbol()
Date: Fri, 21 Feb 2020 07:11:10 -0800
Message-ID: <20200221151109.gxrhyaybjwxqktul@ast-mbp> (raw)
In-Reply-To: <20200221114404.14641-4-will@kernel.org>

On Fri, Feb 21, 2020 at 11:44:04AM +0000, Will Deacon wrote:
> kallsyms_lookup_name() and kallsyms_on_each_symbol() are exported to
> modules despite having no in-tree users and being wide open to abuse by
> out-of-tree modules that can use them as a method to invoke arbitrary
> non-exported kernel functions.
> 
> Unexport kallsyms_lookup_name() and kallsyms_on_each_symbol().
> 
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Quentin Perret <qperret@google.com>
> Signed-off-by: Will Deacon <will@kernel.org>
> ---
>  kernel/kallsyms.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index a9b3f660dee7..16c8c605f4b0 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -175,7 +175,6 @@ unsigned long kallsyms_lookup_name(const char *name)
>  	}
>  	return module_kallsyms_lookup_name(name);
>  }
> -EXPORT_SYMBOL_GPL(kallsyms_lookup_name);
>  
>  int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
>  				      unsigned long),
> @@ -194,7 +193,6 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
>  	}
>  	return module_kallsyms_on_each_symbol(fn, data);
>  }
> -EXPORT_SYMBOL_GPL(kallsyms_on_each_symbol);

Looking at commit 75a66614db21 ("Ksplice: Add functions for walking kallsyms symbols")
this change will break ksplice.
But I think it's the right call. live-patching needs to find a way to be better
integrated with the core kernel.

Acked-by: Alexei Starovoitov <ast@kernel.org>

  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-21 11:44 [PATCH 0/3] " Will Deacon
2020-02-21 11:44 ` [PATCH 1/3] samples/hw_breakpoint: Drop HW_BREAKPOINT_R when reporting writes Will Deacon
2020-02-21 14:12   ` Christoph Hellwig
2020-02-21 11:44 ` [PATCH 2/3] samples/hw_breakpoint: Drop use of kallsyms_lookup_name() Will Deacon
2020-02-21 14:13   ` Christoph Hellwig
2020-02-21 14:20     ` Will Deacon
2020-02-21 11:44 ` [PATCH 3/3] kallsyms: Unexport kallsyms_lookup_name() and kallsyms_on_each_symbol() Will Deacon
2020-02-21 11:53   ` Greg Kroah-Hartman
2020-02-21 14:14   ` Christoph Hellwig
2020-02-21 15:11   ` Alexei Starovoitov [this message]
2020-02-21 14:27 ` [PATCH 0/3] " Masami Hiramatsu
2020-02-21 14:48   ` Will Deacon
2020-02-21 23:44     ` Masami Hiramatsu
2020-02-21 15:41 ` David Laight
2020-02-21 16:25   ` Quentin Perret
2020-02-25 10:05 ` Miroslav Benes
2020-02-25 12:11   ` Petr Mladek
2020-02-25 15:00     ` Joe Lawrence
2020-02-25 18:01       ` Miroslav Benes
2020-02-26 14:16         ` Joe Lawrence
2020-03-02 19:28 ` Mathieu Desnoyers
2020-03-02 19:36   ` Greg Kroah-Hartman
2020-03-02 19:39     ` Greg Kroah-Hartman
2020-03-02 20:17       ` Mathieu Desnoyers
2020-03-03  6:57         ` Greg Kroah-Hartman
2020-03-03 16:58           ` Mathieu Desnoyers

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