linux-kernel - Re: [PATCH v22 11/24] mm: Introduce vm_ops->may

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Date:   Tue, 8 Oct 2019 19:41:18 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-sgx@...r.kernel.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
        kai.svahn@...el.com, josh@...htriplett.org, luto@...nel.org,
        kai.huang@...el.com, rientjes@...gle.com, cedric.xing@...el.com
Subject: Re: [PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect()

+ linux-mm.

On Tue, Sep 03, 2019 at 05:26:42PM +0300, Jarkko Sakkinen wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> Add vm_ops()->may_mprotect() to check additional constrains set by a

constraints

Leaving in the rest for MM folks:

> subsystem for a mprotect() call.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> ---
>  include/linux/mm.h |  2 ++
>  mm/mprotect.c      | 13 ++++++++++---
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0334ca97c584..405cea65057a 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -469,6 +469,8 @@ struct vm_operations_struct {
>  	void (*close)(struct vm_area_struct * area);
>  	int (*split)(struct vm_area_struct * area, unsigned long addr);
>  	int (*mremap)(struct vm_area_struct * area);
> +	int (*may_mprotect)(struct vm_area_struct *vma, unsigned long start,
> +			    unsigned long end, unsigned long prot);
>  	vm_fault_t (*fault)(struct vm_fault *vmf);
>  	vm_fault_t (*huge_fault)(struct vm_fault *vmf,
>  			enum page_entry_size pe_size);
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index bf38dfbbb4b4..18732543b295 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -547,13 +547,20 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  			goto out;
>  		}
>  
> +		tmp = vma->vm_end;
> +		if (tmp > end)
> +			tmp = end;
> +
> +		if (vma->vm_ops && vma->vm_ops->may_mprotect) {
> +			error = vma->vm_ops->may_mprotect(vma, nstart, tmp, prot);
> +			if (error)
> +				goto out;
> +		}
> +
>  		error = security_file_mprotect(vma, reqprot, prot);
>  		if (error)
>  			goto out;
>  
> -		tmp = vma->vm_end;
> -		if (tmp > end)
> -			tmp = end;
>  		error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
>  		if (error)
>  			goto out;
> -- 
> 2.20.1
> 

-- 
Regards/Gruss,
    Boris.

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