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References: <20240109154547.1839886-1-jeffxu@chromium.org> <20240109154547.1839886-3-jeffxu@chromium.org>
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From: Jeff Xu <jeffxu@chromium.org>
Date: Wed, 10 Jan 2024 18:58:48 -0800
Message-ID: <CABi2SkVFVYWiYNCzsfFbkOW4kurysYp2X79prqoHFb488QKbYQ@mail.gmail.com>
Subject: Re: [RFC PATCH v5 2/4] mseal: add mseal syscall
To: Matthew Wilcox <willy@infradead.org>
Cc: akpm@linux-foundation.org, keescook@chromium.org, jannh@google.com, 
	sroettger@google.com, gregkh@linuxfoundation.org, 
	torvalds@linux-foundation.org, usama.anjum@collabora.com, jeffxu@google.com, 
	jorgelo@chromium.org, groeck@chromium.org, linux-kernel@vger.kernel.org, 
	linux-kselftest@vger.kernel.org, linux-mm@kvack.org, pedro.falcato@gmail.com, 
	dave.hansen@intel.com, linux-hardening@vger.kernel.org, deraadt@openbsd.org
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On Tue, Jan 9, 2024 at 12:36=E2=80=AFPM Matthew Wilcox <willy@infradead.org=
> wrote:
>
> On Tue, Jan 09, 2024 at 03:45:40PM +0000, jeffxu@chromium.org wrote:
> > +extern bool can_modify_mm(struct mm_struct *mm, unsigned long start,
> > +             unsigned long end);
> > +extern bool can_modify_mm_madv(struct mm_struct *mm, unsigned long sta=
rt,
> > +             unsigned long end, int behavior);
>
> unnecessary use of extern.
>
> > +static inline unsigned long get_mmap_seals(unsigned long prot,
> > +     unsigned long flags)
>
> needs more than one tab indent so it doesn't look like part of the body.
>
> > +{
> > +     unsigned long vm_seals;
> > +
> > +     if (prot & PROT_SEAL)
> > +             vm_seals =3D VM_SEALED | VM_SEALABLE;
> > +     else
> > +             vm_seals =3D (flags & MAP_SEALABLE) ? VM_SEALABLE:0;
>
> need spaces around the :
>
> > +++ b/include/uapi/asm-generic/mman-common.h
> > @@ -17,6 +17,11 @@
> >  #define PROT_GROWSDOWN       0x01000000      /* mprotect flag: extend =
change to start of growsdown vma */
> >  #define PROT_GROWSUP 0x02000000      /* mprotect flag: extend change t=
o end of growsup vma */
> >
> > +/*
> > + * The PROT_SEAL defines memory sealing in the prot argument of mmap()=
.
> > + */
> > +#define PROT_SEAL    _BITUL(26)      /* 0x04000000 */
>
> why not follow the existing style?
>
> > +static inline void set_vma_sealed(struct vm_area_struct *vma)
> > +{
> > +     vma->__vm_flags |=3D VM_SEALED;
> > +}
>
> uhh ... vm_flags_set() ?
>
Thanks. I agree with all the comments above and will update in the next ver=
sion.

-Jeff