netdev - Re: [PATCH net-next 09/10] arm64: unexport set_memory_ro and set_memory

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Message-ID: <54F0BCCD.4000402@codeaurora.org>
Date:	Fri, 27 Feb 2015 10:51:57 -0800
From:	Laura Abbott <lauraa@...eaurora.org>
To:	Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net
CC:	ast@...mgrid.com, netdev@...r.kernel.org,
	Will Deacon <will.deacon@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 09/10] arm64: unexport set_memory_ro and set_memory_rw

On 2/27/2015 6:55 AM, Daniel Borkmann wrote:
> This effectively unexports set_memory_ro and set_memory_rw functions from
> commit 11d91a770f1f ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX support").
>
> No module user of those is in mainline kernel and we explicitly do not want
> modules to use these functions, as they i.e. protect eBPF (interpreted and
> JIT'ed) images from malicious modifications or bugs.
>
> Outside of eBPF scope, I believe also other set_memory_* functions should
> be unexported on arm64 for modules.
>
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Cc: Laura Abbott <lauraa@...eaurora.org>
> Cc: Will Deacon <will.deacon@....com>
> Cc: linux-kernel@...r.kernel.org
> Acked-by: Alexei Starovoitov <ast@...mgrid.com>
> ---
>   arch/arm64/mm/pageattr.c | 2 --
>   1 file changed, 2 deletions(-)
>

We have some uses for modules doing set_memory_ro/rw but none that are
in mainline. That can be dealt with if the features ever get
mainlined which seems unlikely.

Acked-by: Laura Abbott <lauraa@...eaurora.org>

> diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
> index bb0ea94..8659357 100644
> --- a/arch/arm64/mm/pageattr.c
> +++ b/arch/arm64/mm/pageattr.c
> @@ -70,7 +70,6 @@ int set_memory_ro(unsigned long addr, int numpages)
>   					__pgprot(PTE_RDONLY),
>   					__pgprot(PTE_WRITE));
>   }
> -EXPORT_SYMBOL_GPL(set_memory_ro);
>
>   int set_memory_rw(unsigned long addr, int numpages)
>   {
> @@ -78,7 +77,6 @@ int set_memory_rw(unsigned long addr, int numpages)
>   					__pgprot(PTE_WRITE),
>   					__pgprot(PTE_RDONLY));
>   }
> -EXPORT_SYMBOL_GPL(set_memory_rw);
>
>   int set_memory_nx(unsigned long addr, int numpages)
>   {
>


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