[PATCH 1/2] x86: fix norandmaps

[PATCH 1/2] x86: fix norandmaps

[Oleg Nesterov]

Documentation/admin-guide/kernel-parameters.txt says:

    norandmaps  Don't use address space randomization. Equivalent
                to echo 0 > /proc/sys/kernel/randomize_va_space

but it doesn't work because arch_rnd() which is used to randomize
mm->mmap_base returns a random value unconditionally.

Shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().

Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 arch/x86/mm/mmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 19ad095..6369d04 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -82,13 +82,13 @@ static int mmap_is_legacy(void)
 
 static unsigned long arch_rnd(unsigned int rndbits)
 {
+	if (!(current->flags & PF_RANDOMIZE))
+		return 0;
 	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
 }
 
 unsigned long arch_mmap_rnd(void)
 {
-	if (!(current->flags & PF_RANDOMIZE))
-		return 0;
 	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
 }
 
-- 
2.5.0

[PATCH 2/2] x86/elf: remove the unnecessary ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top()

[Oleg Nesterov]

PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not
set, no need to re-check after that.that.that.that.that.that.that.that.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 arch/x86/mm/mmap.c | 3 +--
 fs/binfmt_elf.c    | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 6369d04..81db3e9 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)
 static unsigned long stack_maxrandom_size(unsigned long task_size)
 {
 	unsigned long max = 0;
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
 		max <<= PAGE_SHIFT;
 	}
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 5075fd5..569c82e 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -666,8 +666,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top)
 {
 	unsigned long random_variable = 0;
 
-	if ((current->flags & PF_RANDOMIZE) &&
-		!(current->personality & ADDR_NO_RANDOMIZE)) {
+	if (current->flags & PF_RANDOMIZE) {
 		random_variable = get_random_long();
 		random_variable &= STACK_RND_MASK;
 		random_variable <<= PAGE_SHIFT;
-- 
2.5.0

Re: [PATCH 2/2] x86/elf: remove the unnecessary ADDR_NO_RANDOMIZE checks in stack_maxrandom_size() and randomize_stack_top()

[Dmitry Safonov]

On 07/10/2017 02:14 PM, Oleg Nesterov wrote:
> PF_RANDOMIZE is set by load_elf_binary() only if ADDR_NO_RANDOMIZE is not
> set, no need to re-check after that.that.that.that.that.that.that.that.
> 
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>

> ---
>   arch/x86/mm/mmap.c | 3 +--
>   fs/binfmt_elf.c    | 3 +--
>   2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
> index 6369d04..81db3e9 100644
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -50,8 +50,7 @@ unsigned long tasksize_64bit(void)
>   static unsigned long stack_maxrandom_size(unsigned long task_size)
>   {
>   	unsigned long max = 0;
> -	if ((current->flags & PF_RANDOMIZE) &&
> -		!(current->personality & ADDR_NO_RANDOMIZE)) {
> +	if (current->flags & PF_RANDOMIZE) {
>   		max = (-1UL) & __STACK_RND_MASK(task_size == tasksize_32bit());
>   		max <<= PAGE_SHIFT;
>   	}
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index 5075fd5..569c82e 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -666,8 +666,7 @@ static unsigned long randomize_stack_top(unsigned long stack_top)
>   {
>   	unsigned long random_variable = 0;
>   
> -	if ((current->flags & PF_RANDOMIZE) &&
> -		!(current->personality & ADDR_NO_RANDOMIZE)) {
> +	if (current->flags & PF_RANDOMIZE) {
>   		random_variable = get_random_long();
>   		random_variable &= STACK_RND_MASK;
>   		random_variable <<= PAGE_SHIFT;
> 


-- 
              Dmitry

Re: [PATCH 1/2] x86: fix norandmaps

[Dmitry Safonov]

On 07/10/2017 02:14 PM, Oleg Nesterov wrote:
> Documentation/admin-guide/kernel-parameters.txt says:
> 
>      norandmaps  Don't use address space randomization. Equivalent
>                  to echo 0 > /proc/sys/kernel/randomize_va_space
> 
> but it doesn't work because arch_rnd() which is used to randomize
> mm->mmap_base returns a random value unconditionally.
> 
> Shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
> 
> Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Thanks, Oleg,
Reviewed-by: Dmitry Safonov <dsafonov@virtuozzo.com>

> ---
>   arch/x86/mm/mmap.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
> index 19ad095..6369d04 100644
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -82,13 +82,13 @@ static int mmap_is_legacy(void)
>   
>   static unsigned long arch_rnd(unsigned int rndbits)
>   {
> +	if (!(current->flags & PF_RANDOMIZE))
> +		return 0;
>   	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
>   }
>   
>   unsigned long arch_mmap_rnd(void)
>   {
> -	if (!(current->flags & PF_RANDOMIZE))
> -		return 0;
>   	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
>   }
>   
> 


-- 
              Dmitry

Re: [PATCH 1/2] x86: fix norandmaps

[Oleg Nesterov]

ping ;)

On 07/10, Oleg Nesterov wrote:
>
> Documentation/admin-guide/kernel-parameters.txt says:
> 
>     norandmaps  Don't use address space randomization. Equivalent
>                 to echo 0 > /proc/sys/kernel/randomize_va_space
> 
> but it doesn't work because arch_rnd() which is used to randomize
> mm->mmap_base returns a random value unconditionally.
> 
> Shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
> 
> Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
>  arch/x86/mm/mmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
> index 19ad095..6369d04 100644
> --- a/arch/x86/mm/mmap.c
> +++ b/arch/x86/mm/mmap.c
> @@ -82,13 +82,13 @@ static int mmap_is_legacy(void)
>  
>  static unsigned long arch_rnd(unsigned int rndbits)
>  {
> +	if (!(current->flags & PF_RANDOMIZE))
> +		return 0;
>  	return (get_random_long() & ((1UL << rndbits) - 1)) << PAGE_SHIFT;
>  }
>  
>  unsigned long arch_mmap_rnd(void)
>  {
> -	if (!(current->flags & PF_RANDOMIZE))
> -		return 0;
>  	return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits);
>  }
>  
> -- 
> 2.5.0
> 

Re: [PATCH 1/2] x86: fix norandmaps

[Kirill A. Shutemov]

On Mon, Jul 10, 2017 at 01:14:29PM +0200, Oleg Nesterov wrote:
> Documentation/admin-guide/kernel-parameters.txt says:
> 
>     norandmaps  Don't use address space randomization. Equivalent
>                 to echo 0 > /proc/sys/kernel/randomize_va_space
> 
> but it doesn't work because arch_rnd() which is used to randomize
> mm->mmap_base returns a random value unconditionally.
> 
> Shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
> 
> Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

It also fixes personality(ADDR_NO_RANDOMIZE).

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov

Re: [PATCH 1/2] x86: fix norandmaps

[Oleg Nesterov]

On 08/14, Kirill A. Shutemov wrote:
>
> On Mon, Jul 10, 2017 at 01:14:29PM +0200, Oleg Nesterov wrote:
> > Documentation/admin-guide/kernel-parameters.txt says:
> > 
> >     norandmaps  Don't use address space randomization. Equivalent
> >                 to echo 0 > /proc/sys/kernel/randomize_va_space
> > 
> > but it doesn't work because arch_rnd() which is used to randomize
> > mm->mmap_base returns a random value unconditionally.
> > 
> > Shift the PF_RANDOMIZE check from arch_mmap_rnd() to arch_rnd().
> > 
> > Fixes: 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
> > Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> 
> It also fixes personality(ADDR_NO_RANDOMIZE).

Yes, good point.

> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

OK, thanks Kirill and Cyrill, I'll resend tomorrow with all acks I got.

Oleg.

Re: [PATCH 1/2] x86: fix norandmaps

[Cyrill Gorcunov]

On Mon, Aug 14, 2017 at 06:43:10PM +0200, Oleg Nesterov wrote:
> > Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> 
> OK, thanks Kirill and Cyrill, I'll resend tomorrow with all acks I got.

I don't think you need my ack but if any
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>