[v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

[PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by Eric W. Biederman 11 months, 2 weeks ago


Richard Henderson <richard.henderson@linaro.org> writes[1]:

> There was a Spec benchmark (I forget which) which was memory bound and ran
> twice as fast with 32-bit pointers.
>
> I copied the idea from DEC to the ELF abi, but never did all the other work
> to allow the toolchain to take advantage.
>
> Amusingly, a later Spec changed the benchmark data sets to not fit into a
> 32-bit address space, specifically because of this.
>
> I expect one could delete the ELF bit and personality and no one would
> notice. Not even the 10 remaining Alpha users.

In [2] it was pointed out that parts of setarch weren't working
properly on alpha because it has it's own SET_PERSONALITY
implementation.  In the discussion that followed Richard Henderson
pointed out that the 32bit pointer support for alpha was never
completed.

Fix this by removing alpha's 32bit pointer support.

As a bit of paranoia refuse to execute any alpha binaries that have
the EF_ALPHA_32BIT flag set.  Just in case someone somewhere has
binaries that try to use alpha's 32bit pointer support.

[1] https://lkml.kernel.org/r/CAFXwXrkgu=4Qn-v1PjnOR4SG0oUb9LSa0g6QXpBq4ttm52pJOQ@mail.gmail.com
[2] https://lkml.kernel.org/r/20250103140148.370368-1-glaubitz@physik.fu-berlin.de
v1: https://lkml.kernel.org/r/87jzb2tdb7.fsf_-_@email.froward.int.ebiederm.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---

Kees can you pick this one up?

 arch/alpha/include/asm/elf.h       |  6 +-----
 arch/alpha/include/asm/pgtable.h   |  2 +-
 arch/alpha/include/asm/processor.h |  8 ++------
 arch/alpha/kernel/osf_sys.c        | 11 ++---------
 4 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/arch/alpha/include/asm/elf.h b/arch/alpha/include/asm/elf.h
index 4d7c46f50382..50c82187e60e 100644
--- a/arch/alpha/include/asm/elf.h
+++ b/arch/alpha/include/asm/elf.h
@@ -74,7 +74,7 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
 /*
  * This is used to ensure we don't load something for the wrong architecture.
  */
-#define elf_check_arch(x) ((x)->e_machine == EM_ALPHA)
+#define elf_check_arch(x) (((x)->e_machine == EM_ALPHA) && !((x)->e_flags & EF_ALPHA_32BIT))
 
 /*
  * These are used to set parameters in the core dumps.
@@ -137,10 +137,6 @@ extern int dump_elf_task(elf_greg_t *dest, struct task_struct *task);
 	: amask (AMASK_CIX) ? "ev6" : "ev67");	\
 })
 
-#define SET_PERSONALITY(EX)					\
-	set_personality(((EX).e_flags & EF_ALPHA_32BIT)		\
-	   ? PER_LINUX_32BIT : PER_LINUX)
-
 extern int alpha_l1i_cacheshape;
 extern int alpha_l1d_cacheshape;
 extern int alpha_l2_cacheshape;
diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
index 635f0a5f5bbd..02e8817a8921 100644
--- a/arch/alpha/include/asm/pgtable.h
+++ b/arch/alpha/include/asm/pgtable.h
@@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 
 extern void paging_init(void);
 
-/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
+/* We have our own get_unmapped_area */
 #define HAVE_ARCH_UNMAPPED_AREA
 
 #endif /* _ALPHA_PGTABLE_H */
diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
index 55bb1c09fd39..5dce5518a211 100644
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -8,23 +8,19 @@
 #ifndef __ASM_ALPHA_PROCESSOR_H
 #define __ASM_ALPHA_PROCESSOR_H
 
-#include <linux/personality.h>	/* for ADDR_LIMIT_32BIT */
-
 /*
  * We have a 42-bit user address space: 4TB user VM...
  */
 #define TASK_SIZE (0x40000000000UL)
 
-#define STACK_TOP \
-  (current->personality & ADDR_LIMIT_32BIT ? 0x80000000 : 0x00120000000UL)
+#define STACK_TOP (0x00120000000UL)
 
 #define STACK_TOP_MAX	0x00120000000UL
 
 /* This decides where the kernel will search for a free chunk of vm
  * space during mmap's.
  */
-#define TASK_UNMAPPED_BASE \
-  ((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2)
+#define TASK_UNMAPPED_BASE (TASK_SIZE / 2)
 
 /* This is dead.  Everything has been moved to thread_info.  */
 struct thread_struct { };
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index 86185021f75a..a08e8edef1a4 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -1210,8 +1210,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
 	return ret;
 }
 
-/* Get an address range which is currently unmapped.  Similar to the
-   generic version except that we know how to honor ADDR_LIMIT_32BIT.  */
+/* Get an address range which is currently unmapped. */
 
 static unsigned long
 arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
@@ -1230,13 +1229,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 		       unsigned long len, unsigned long pgoff,
 		       unsigned long flags, vm_flags_t vm_flags)
 {
-	unsigned long limit;
-
-	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
-	if (current->personality & ADDR_LIMIT_32BIT)
-		limit = 0x80000000;
-	else
-		limit = TASK_SIZE;
+	unsigned long limit = TASK_SIZE;
 
 	if (len > limit)
 		return -ENOMEM;
-- 
2.41.0

Re: [PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by Kees Cook 10 months, 2 weeks ago

On Sun, 12 Jan 2025 23:39:01 -0600, Eric W. Biederman wrote:
> Richard Henderson <richard.henderson@linaro.org> writes[1]:
> 
> > There was a Spec benchmark (I forget which) which was memory bound and ran
> > twice as fast with 32-bit pointers.
> >
> > I copied the idea from DEC to the ELF abi, but never did all the other work
> > to allow the toolchain to take advantage.
> >
> > Amusingly, a later Spec changed the benchmark data sets to not fit into a
> > 32-bit address space, specifically because of this.
> >
> > I expect one could delete the ELF bit and personality and no one would
> > notice. Not even the 10 remaining Alpha users.
> 
> [...]

Applied to for-next/topic/execve/core, thanks!

[1/1] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support
      https://git.kernel.org/kees/c/b029628be267

Take care,

-- 
Kees Cook

Re: [PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by John Paul Adrian Glaubitz 10 months, 3 weeks ago

Hi,

On Sun, 2025-01-12 at 23:39 -0600, Eric W. Biederman wrote:
> Richard Henderson <richard.henderson@linaro.org> writes[1]:
> 
> > There was a Spec benchmark (I forget which) which was memory bound and ran
> > twice as fast with 32-bit pointers.
> > 
> > I copied the idea from DEC to the ELF abi, but never did all the other work
> > to allow the toolchain to take advantage.
> > 
> > Amusingly, a later Spec changed the benchmark data sets to not fit into a
> > 32-bit address space, specifically because of this.
> > 
> > I expect one could delete the ELF bit and personality and no one would
> > notice. Not even the 10 remaining Alpha users.
> 
> In [2] it was pointed out that parts of setarch weren't working
> properly on alpha because it has it's own SET_PERSONALITY
> implementation.  In the discussion that followed Richard Henderson
> pointed out that the 32bit pointer support for alpha was never
> completed.
> 
> Fix this by removing alpha's 32bit pointer support.
> 
> As a bit of paranoia refuse to execute any alpha binaries that have
> the EF_ALPHA_32BIT flag set.  Just in case someone somewhere has
> binaries that try to use alpha's 32bit pointer support.
> 
> [1] https://lkml.kernel.org/r/CAFXwXrkgu=4Qn-v1PjnOR4SG0oUb9LSa0g6QXpBq4ttm52pJOQ@mail.gmail.com
> [2] https://lkml.kernel.org/r/20250103140148.370368-1-glaubitz@physik.fu-berlin.de
> v1: https://lkml.kernel.org/r/87jzb2tdb7.fsf_-_@email.froward.int.ebiederm.org
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
> Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
> Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
> 
> Kees can you pick this one up?
> 
>  arch/alpha/include/asm/elf.h       |  6 +-----
>  arch/alpha/include/asm/pgtable.h   |  2 +-
>  arch/alpha/include/asm/processor.h |  8 ++------
>  arch/alpha/kernel/osf_sys.c        | 11 ++---------
>  4 files changed, 6 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/alpha/include/asm/elf.h b/arch/alpha/include/asm/elf.h
> index 4d7c46f50382..50c82187e60e 100644
> --- a/arch/alpha/include/asm/elf.h
> +++ b/arch/alpha/include/asm/elf.h
> @@ -74,7 +74,7 @@ typedef elf_fpreg_t elf_fpregset_t[ELF_NFPREG];
>  /*
>   * This is used to ensure we don't load something for the wrong architecture.
>   */
> -#define elf_check_arch(x) ((x)->e_machine == EM_ALPHA)
> +#define elf_check_arch(x) (((x)->e_machine == EM_ALPHA) && !((x)->e_flags & EF_ALPHA_32BIT))
>  
>  /*
>   * These are used to set parameters in the core dumps.
> @@ -137,10 +137,6 @@ extern int dump_elf_task(elf_greg_t *dest, struct task_struct *task);
>  	: amask (AMASK_CIX) ? "ev6" : "ev67");	\
>  })
>  
> -#define SET_PERSONALITY(EX)					\
> -	set_personality(((EX).e_flags & EF_ALPHA_32BIT)		\
> -	   ? PER_LINUX_32BIT : PER_LINUX)
> -
>  extern int alpha_l1i_cacheshape;
>  extern int alpha_l1d_cacheshape;
>  extern int alpha_l2_cacheshape;
> diff --git a/arch/alpha/include/asm/pgtable.h b/arch/alpha/include/asm/pgtable.h
> index 635f0a5f5bbd..02e8817a8921 100644
> --- a/arch/alpha/include/asm/pgtable.h
> +++ b/arch/alpha/include/asm/pgtable.h
> @@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
>  
>  extern void paging_init(void);
>  
> -/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
> +/* We have our own get_unmapped_area */
>  #define HAVE_ARCH_UNMAPPED_AREA
>  
>  #endif /* _ALPHA_PGTABLE_H */
> diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
> index 55bb1c09fd39..5dce5518a211 100644
> --- a/arch/alpha/include/asm/processor.h
> +++ b/arch/alpha/include/asm/processor.h
> @@ -8,23 +8,19 @@
>  #ifndef __ASM_ALPHA_PROCESSOR_H
>  #define __ASM_ALPHA_PROCESSOR_H
>  
> -#include <linux/personality.h>	/* for ADDR_LIMIT_32BIT */
> -
>  /*
>   * We have a 42-bit user address space: 4TB user VM...
>   */
>  #define TASK_SIZE (0x40000000000UL)
>  
> -#define STACK_TOP \
> -  (current->personality & ADDR_LIMIT_32BIT ? 0x80000000 : 0x00120000000UL)
> +#define STACK_TOP (0x00120000000UL)
>  
>  #define STACK_TOP_MAX	0x00120000000UL
>  
>  /* This decides where the kernel will search for a free chunk of vm
>   * space during mmap's.
>   */
> -#define TASK_UNMAPPED_BASE \
> -  ((current->personality & ADDR_LIMIT_32BIT) ? 0x40000000 : TASK_SIZE / 2)
> +#define TASK_UNMAPPED_BASE (TASK_SIZE / 2)
>  
>  /* This is dead.  Everything has been moved to thread_info.  */
>  struct thread_struct { };
> diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
> index 86185021f75a..a08e8edef1a4 100644
> --- a/arch/alpha/kernel/osf_sys.c
> +++ b/arch/alpha/kernel/osf_sys.c
> @@ -1210,8 +1210,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
>  	return ret;
>  }
>  
> -/* Get an address range which is currently unmapped.  Similar to the
> -   generic version except that we know how to honor ADDR_LIMIT_32BIT.  */
> +/* Get an address range which is currently unmapped. */
>  
>  static unsigned long
>  arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
> @@ -1230,13 +1229,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>  		       unsigned long len, unsigned long pgoff,
>  		       unsigned long flags, vm_flags_t vm_flags)
>  {
> -	unsigned long limit;
> -
> -	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
> -	if (current->personality & ADDR_LIMIT_32BIT)
> -		limit = 0x80000000;
> -	else
> -		limit = TASK_SIZE;
> +	unsigned long limit = TASK_SIZE;
>  
>  	if (len > limit)
>  		return -ENOMEM;

Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Can someone pick up this patch for v6.14?

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: [PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by Ivan Kokshaysky 11 months, 1 week ago

On Sun, Jan 12, 2025 at 11:39:01PM -0600, Eric W. Biederman wrote:
...
> --- a/arch/alpha/include/asm/pgtable.h
> +++ b/arch/alpha/include/asm/pgtable.h
> @@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
>  
>  extern void paging_init(void);
>  
> -/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
> +/* We have our own get_unmapped_area */
>  #define HAVE_ARCH_UNMAPPED_AREA

Just remove the definition. As the comment suggests, the only reason
it exists is ADDR_LIMIT_32BIT, which is gone.

> --- a/arch/alpha/kernel/osf_sys.c
> +++ b/arch/alpha/kernel/osf_sys.c
> @@ -1210,8 +1210,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
>  	return ret;
>  }
>  
> -/* Get an address range which is currently unmapped.  Similar to the
> -   generic version except that we know how to honor ADDR_LIMIT_32BIT.  */
> +/* Get an address range which is currently unmapped. */
>  
>  static unsigned long
>  arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
> @@ -1230,13 +1229,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
>  		       unsigned long len, unsigned long pgoff,
>  		       unsigned long flags, vm_flags_t vm_flags)
>  {
> -	unsigned long limit;
> -
> -	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
> -	if (current->personality & ADDR_LIMIT_32BIT)
> -		limit = 0x80000000;
> -	else
> -		limit = TASK_SIZE;
> +	unsigned long limit = TASK_SIZE;
>  
>  	if (len > limit)
>  		return -ENOMEM;

Likewise, just remove these functions. The generic_get_unmapped_area()
works fine, tested on up1500.

Ivan.

Re: [PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by John Paul Adrian Glaubitz 11 months ago

Hi Eric,

On Sat, 2025-01-18 at 11:35 +0100, Ivan Kokshaysky wrote:
> On Sun, Jan 12, 2025 at 11:39:01PM -0600, Eric W. Biederman wrote:
> ...
> > --- a/arch/alpha/include/asm/pgtable.h
> > +++ b/arch/alpha/include/asm/pgtable.h
> > @@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> >  
> >  extern void paging_init(void);
> >  
> > -/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
> > +/* We have our own get_unmapped_area */
> >  #define HAVE_ARCH_UNMAPPED_AREA
> 
> Just remove the definition. As the comment suggests, the only reason
> it exists is ADDR_LIMIT_32BIT, which is gone.
> 
> > --- a/arch/alpha/kernel/osf_sys.c
> > +++ b/arch/alpha/kernel/osf_sys.c
> > @@ -1210,8 +1210,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
> >  	return ret;
> >  }
> >  
> > -/* Get an address range which is currently unmapped.  Similar to the
> > -   generic version except that we know how to honor ADDR_LIMIT_32BIT.  */
> > +/* Get an address range which is currently unmapped. */
> >  
> >  static unsigned long
> >  arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
> > @@ -1230,13 +1229,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
> >  		       unsigned long len, unsigned long pgoff,
> >  		       unsigned long flags, vm_flags_t vm_flags)
> >  {
> > -	unsigned long limit;
> > -
> > -	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
> > -	if (current->personality & ADDR_LIMIT_32BIT)
> > -		limit = 0x80000000;
> > -	else
> > -		limit = TASK_SIZE;
> > +	unsigned long limit = TASK_SIZE;
> >  
> >  	if (len > limit)
> >  		return -ENOMEM;
> 
> Likewise, just remove these functions. The generic_get_unmapped_area()
> works fine, tested on up1500.

Can you send a follow-up integrating those changes? It would be good if
SET_PERSONALITY() could be fixed on alpha for v6.14.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913

Re: [PATCH v2] alpha/elf: Fix misc/setarch test of util-linux by removing 32bit support

Posted by Ivan Kokshaysky 10 months, 4 weeks ago

On Sun, Jan 26, 2025 at 06:15:43PM +0100, John Paul Adrian Glaubitz wrote:
> Hi Eric,
> 
> On Sat, 2025-01-18 at 11:35 +0100, Ivan Kokshaysky wrote:
> > On Sun, Jan 12, 2025 at 11:39:01PM -0600, Eric W. Biederman wrote:
> > ...
> > > --- a/arch/alpha/include/asm/pgtable.h
> > > +++ b/arch/alpha/include/asm/pgtable.h
> > > @@ -360,7 +360,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> > >  
> > >  extern void paging_init(void);
> > >  
> > > -/* We have our own get_unmapped_area to cope with ADDR_LIMIT_32BIT.  */
> > > +/* We have our own get_unmapped_area */
> > >  #define HAVE_ARCH_UNMAPPED_AREA
> > 
> > Just remove the definition. As the comment suggests, the only reason
> > it exists is ADDR_LIMIT_32BIT, which is gone.
> > 
> > > --- a/arch/alpha/kernel/osf_sys.c
> > > +++ b/arch/alpha/kernel/osf_sys.c
> > > @@ -1210,8 +1210,7 @@ SYSCALL_DEFINE1(old_adjtimex, struct timex32 __user *, txc_p)
> > >  	return ret;
> > >  }
> > >  
> > > -/* Get an address range which is currently unmapped.  Similar to the
> > > -   generic version except that we know how to honor ADDR_LIMIT_32BIT.  */
> > > +/* Get an address range which is currently unmapped. */
> > >  
> > >  static unsigned long
> > >  arch_get_unmapped_area_1(unsigned long addr, unsigned long len,
> > > @@ -1230,13 +1229,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
> > >  		       unsigned long len, unsigned long pgoff,
> > >  		       unsigned long flags, vm_flags_t vm_flags)
> > >  {
> > > -	unsigned long limit;
> > > -
> > > -	/* "32 bit" actually means 31 bit, since pointers sign extend.  */
> > > -	if (current->personality & ADDR_LIMIT_32BIT)
> > > -		limit = 0x80000000;
> > > -	else
> > > -		limit = TASK_SIZE;
> > > +	unsigned long limit = TASK_SIZE;
> > >  
> > >  	if (len > limit)
> > >  		return -ENOMEM;
> > 
> > Likewise, just remove these functions. The generic_get_unmapped_area()
> > works fine, tested on up1500.
> 
> Can you send a follow-up integrating those changes? It would be good if
> SET_PERSONALITY() could be fixed on alpha for v6.14.

Oh, the changes I proposed are mere cleanup suggestions.
The original patch would do just fine.

Ivan.