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Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions

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  Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native  versions Borislav Petkov <bp@alien8.de> - 2017-02-09 15:20 +0100
    Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions Andy Lutomirski <luto@amacapital.net> - 2017-02-10 00:10 +0100
    Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native  versions Thomas Gleixner <tglx@linutronix.de> - 2017-02-10 21:20 +0100
      Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native  versions Borislav Petkov <bp@suse.de> - 2017-02-10 21:30 +0100
      Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions Dmitry Safonov <0x7f454c46@gmail.com> - 2017-02-10 22:30 +0100
        Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native  versions Thomas Gleixner <tglx@linutronix.de> - 2017-02-11 09:30 +0100
          Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native  versions Thomas Gleixner <tglx@linutronix.de> - 2017-02-13 12:30 +0100

#1577627 — Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions

On Mon, Jan 30, 2017 at 03:04:28PM +0300, Dmitry Safonov wrote:
> I need those arch_{native,compat}_rnd() to compute separately
> random factor for mmap() in compat syscalls for 64-bit binaries
> and vice-versa for native syscall in 32-bit compat binaries.
> They will be used in the following patches.
> 
> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
> ---
>  arch/x86/mm/mmap.c | 25 ++++++++++++++++---------
>  1 file changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
> index d2dc0438d654..42063e787717 100644
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -65,20 +65,27 @@ static int mmap_is_legacy(void)
>  	return sysctl_legacy_va_layout;
>  }
>  
> -unsigned long arch_mmap_rnd(void)
> +#ifdef CONFIG_COMPAT
> +static unsigned long arch_compat_rnd(void)
>  {
> -	unsigned long rnd;
> +	return (get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1))
> +		<< PAGE_SHIFT;
> +}
> +#endif
>  
> -	if (mmap_is_ia32())
> +static unsigned long arch_native_rnd(void)
> +{
> +	return (get_random_long() & ((1UL << mmap_rnd_bits) - 1)) << PAGE_SHIFT;
> +}
> +
> +unsigned long arch_mmap_rnd(void)
> +{
>  #ifdef CONFIG_COMPAT
> -		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
> -#else
> -		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> +	if (mmap_is_ia32())
> +		return arch_compat_rnd();
>  #endif

I can't say that I'm thrilled about the ifdeffery this is adding.

But I can't think of a cleaner approach at a quick glance, though -
that's generic and arch-specific code intertwined muck. Sad face.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

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#1578027 — Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions

On Thu, Feb 9, 2017 at 5:55 AM, Borislav Petkov <bp@alien8.de> wrote:
> On Mon, Jan 30, 2017 at 03:04:28PM +0300, Dmitry Safonov wrote:
>> I need those arch_{native,compat}_rnd() to compute separately
>> random factor for mmap() in compat syscalls for 64-bit binaries
>> and vice-versa for native syscall in 32-bit compat binaries.
>> They will be used in the following patches.
>>
>> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
>> ---
>>  arch/x86/mm/mmap.c | 25 ++++++++++++++++---------
>>  1 file changed, 16 insertions(+), 9 deletions(-)
>>
>> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
>> index d2dc0438d654..42063e787717 100644
>> --- a/arch/x86/mm/mmap.c
>> +++ b/arch/x86/mm/mmap.c
>> @@ -65,20 +65,27 @@ static int mmap_is_legacy(void)
>>       return sysctl_legacy_va_layout;
>>  }
>>
>> -unsigned long arch_mmap_rnd(void)
>> +#ifdef CONFIG_COMPAT
>> +static unsigned long arch_compat_rnd(void)
>>  {
>> -     unsigned long rnd;
>> +     return (get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1))
>> +             << PAGE_SHIFT;
>> +}
>> +#endif
>>
>> -     if (mmap_is_ia32())
>> +static unsigned long arch_native_rnd(void)
>> +{
>> +     return (get_random_long() & ((1UL << mmap_rnd_bits) - 1)) << PAGE_SHIFT;
>> +}
>> +
>> +unsigned long arch_mmap_rnd(void)
>> +{
>>  #ifdef CONFIG_COMPAT
>> -             rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
>> -#else
>> -             rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
>> +     if (mmap_is_ia32())
>> +             return arch_compat_rnd();
>>  #endif
>
> I can't say that I'm thrilled about the ifdeffery this is adding.
>
> But I can't think of a cleaner approach at a quick glance, though -
> that's generic and arch-specific code intertwined muck. Sad face.

I can, but it could be considerably more churn: get rid of the
compat/native split and do a 32-bit/64-bit split instead.

>
> --
> Regards/Gruss,
>     Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.



-- 
Andy Lutomirski
AMA Capital Management, LLC

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#1578773

On Thu, 9 Feb 2017, Borislav Petkov wrote:
> I can't say that I'm thrilled about the ifdeffery this is adding.
> 
> But I can't think of a cleaner approach at a quick glance, though -
> that's generic and arch-specific code intertwined muck. Sad face.

It's trivial enough to do ....

Thanks,

	tglx

---
 arch/x86/mm/mmap.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
 #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
 #define MAX_GAP (TASK_SIZE/6*5)
 
+#ifndef CONFIG_COMPAT
+# define mmap_rnd_compat_bits	mmap_rnd_bits
+#endif
+
 static int mmap_is_legacy(void)
 {
 	if (current->personality & ADDR_COMPAT_LAYOUT)
@@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
 	return sysctl_legacy_va_layout;
 }
 
-unsigned long arch_mmap_rnd(void)
+static unsigned long arch_rnd(unsigned int rndbits)
 {
-	unsigned long rnd;
-
-	if (mmap_is_ia32())
-#ifdef CONFIG_COMPAT
-		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
-#else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-#endif
-	else
-		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
+	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
+}
 
-	return rnd << PAGE_SHIFT;
+unsigned long arch_mmap_rnd(void)
+{
+	return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
 }
 
 static unsigned long mmap_base(unsigned long rnd)

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#1578777

On Fri, Feb 10, 2017 at 09:10:30PM +0100, Thomas Gleixner wrote:
> On Thu, 9 Feb 2017, Borislav Petkov wrote:
> > I can't say that I'm thrilled about the ifdeffery this is adding.
> > 
> > But I can't think of a cleaner approach at a quick glance, though -
> > that's generic and arch-specific code intertwined muck. Sad face.
> 
> It's trivial enough to do ....
> 
> Thanks,
> 
> 	tglx
> 
> ---
>  arch/x86/mm/mmap.c |   22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
>  #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
>  #define MAX_GAP (TASK_SIZE/6*5)
>  
> +#ifndef CONFIG_COMPAT
> +# define mmap_rnd_compat_bits	mmap_rnd_bits
> +#endif
> +
>  static int mmap_is_legacy(void)
>  {
>  	if (current->personality & ADDR_COMPAT_LAYOUT)
> @@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
>  	return sysctl_legacy_va_layout;
>  }
>  
> -unsigned long arch_mmap_rnd(void)
> +static unsigned long arch_rnd(unsigned int rndbits)
>  {
> -	unsigned long rnd;
> -
> -	if (mmap_is_ia32())
> -#ifdef CONFIG_COMPAT
> -		rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
> -#else
> -		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> -#endif
> -	else
> -		rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> +	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
> +}
>  
> -	return rnd << PAGE_SHIFT;
> +unsigned long arch_mmap_rnd(void)
> +{
> +	return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
>  }

Ha! Nice. :-)

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
-- 

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#1578812 — Re: [PATCHv4 1/5] x86/mm: split arch_mmap_rnd() on compat/native versions

2017-02-10 23:10 GMT+03:00 Thomas Gleixner <tglx@linutronix.de>:
> On Thu, 9 Feb 2017, Borislav Petkov wrote:
>> I can't say that I'm thrilled about the ifdeffery this is adding.
>>
>> But I can't think of a cleaner approach at a quick glance, though -
>> that's generic and arch-specific code intertwined muck. Sad face.
>
> It's trivial enough to do ....
>
> Thanks,
>
>         tglx
>
> ---
>  arch/x86/mm/mmap.c |   22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
>  #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
>  #define MAX_GAP (TASK_SIZE/6*5)
>
> +#ifndef CONFIG_COMPAT
> +# define mmap_rnd_compat_bits  mmap_rnd_bits
> +#endif
> +

From my POV, I can't say that it's clearer to shadow mmap_compat_bits
like that then to have two functions with native/compat names.
But if you insist, I'll resend patches set with your version.

>  static int mmap_is_legacy(void)
>  {
>         if (current->personality & ADDR_COMPAT_LAYOUT)
> @@ -66,20 +70,14 @@ static int mmap_is_legacy(void)
>         return sysctl_legacy_va_layout;
>  }
>
> -unsigned long arch_mmap_rnd(void)
> +static unsigned long arch_rnd(unsigned int rndbits)
>  {
> -       unsigned long rnd;
> -
> -       if (mmap_is_ia32())
> -#ifdef CONFIG_COMPAT
> -               rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
> -#else
> -               rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> -#endif
> -       else
> -               rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> +       return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
> +}
>
> -       return rnd << PAGE_SHIFT;
> +unsigned long arch_mmap_rnd(void)
> +{
> +       return arch_rnd(mmap_is_ia32() ? mmap_rnd_compat_bits : mmap_rnd_bits);
>  }
>
>  static unsigned long mmap_base(unsigned long rnd)

-- 
             Dmitry

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#1578954

On Sat, 11 Feb 2017, Dmitry Safonov wrote:

> 2017-02-10 23:10 GMT+03:00 Thomas Gleixner <tglx@linutronix.de>:
> > On Thu, 9 Feb 2017, Borislav Petkov wrote:
> >> I can't say that I'm thrilled about the ifdeffery this is adding.
> >>
> >> But I can't think of a cleaner approach at a quick glance, though -
> >> that's generic and arch-specific code intertwined muck. Sad face.
> >
> > It's trivial enough to do ....
> >
> > Thanks,
> >
> >         tglx
> >
> > ---
> >  arch/x86/mm/mmap.c |   22 ++++++++++------------
> >  1 file changed, 10 insertions(+), 12 deletions(-)
> >
> > --- a/arch/x86/mm/mmap.c
> > +++ b/arch/x86/mm/mmap.c
> > @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
> >  #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
> >  #define MAX_GAP (TASK_SIZE/6*5)
> >
> > +#ifndef CONFIG_COMPAT
> > +# define mmap_rnd_compat_bits  mmap_rnd_bits
> > +#endif
> > +
> 
> >From my POV, I can't say that it's clearer to shadow mmap_compat_bits
> like that then to have two functions with native/compat names.
> But if you insist, I'll resend patches set with your version.

You can make that

#ifdef CONFIG_64BIT
# define mmap32_rnd_bits  mmap_compat_rnd_bits
# define mmap64_rnd_bits  mmap_rnd_bits
#else
# define mmap32_rnd_bits  mmap_rnd_bits
# define mmap64_rnd_bits  mmap_rnd_bits
#endif

and use that. That's still way more readable than the unholy ifdef mess.

Thanks,

	tglx

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#1579643

On Mon, 13 Feb 2017, Dmitry Safonov wrote:
> On 02/11/2017 11:23 AM, Thomas Gleixner wrote:
> > On Sat, 11 Feb 2017, Dmitry Safonov wrote:
> > 
> > > 2017-02-10 23:10 GMT+03:00 Thomas Gleixner <tglx@linutronix.de>:
> > > > On Thu, 9 Feb 2017, Borislav Petkov wrote:
> > > > > I can't say that I'm thrilled about the ifdeffery this is adding.
> > > > > 
> > > > > But I can't think of a cleaner approach at a quick glance, though -
> > > > > that's generic and arch-specific code intertwined muck. Sad face.
> > > > 
> > > > It's trivial enough to do ....
> > > > 
> > > > Thanks,
> > > > 
> > > >         tglx
> > > > 
> > > > ---
> > > >  arch/x86/mm/mmap.c |   22 ++++++++++------------
> > > >  1 file changed, 10 insertions(+), 12 deletions(-)
> > > > 
> > > > --- a/arch/x86/mm/mmap.c
> > > > +++ b/arch/x86/mm/mmap.c
> > > > @@ -55,6 +55,10 @@ static unsigned long stack_maxrandom_siz
> > > >  #define MIN_GAP (128*1024*1024UL + stack_maxrandom_size())
> > > >  #define MAX_GAP (TASK_SIZE/6*5)
> > > > 
> > > > +#ifndef CONFIG_COMPAT
> > > > +# define mmap_rnd_compat_bits  mmap_rnd_bits
> > > > +#endif
> > > > +
> > > 
> > > >From my POV, I can't say that it's clearer to shadow mmap_compat_bits
> > > like that then to have two functions with native/compat names.
> > > But if you insist, I'll resend patches set with your version.
> > 
> > You can make that
> > 
> > #ifdef CONFIG_64BIT
> > # define mmap32_rnd_bits  mmap_compat_rnd_bits
> > # define mmap64_rnd_bits  mmap_rnd_bits
> > #else
> > # define mmap32_rnd_bits  mmap_rnd_bits
> > # define mmap64_rnd_bits  mmap_rnd_bits
> > #endif
> > 
> > and use that. That's still way more readable than the unholy ifdef mess.
> 
> Ok, will send this version in v5.
> Ping me if you mind me using your SOB for this patch.

Suggested-by is enough

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