Re: [PATCH ARM64 v4.4 V3 11/44] arm64: uaccess: Mask __user pointers for __arch_{clear, copy_*}_user

[Mark Rutland <mark.rutland@arm.com>]

On Thu, Aug 29, 2019 at 05:03:56PM +0530, Viresh Kumar wrote:
> From: Will Deacon <will.deacon@arm.com>
> 
> commit f71c2ffcb20dd8626880747557014bb9a61eb90e upstream.
> 
> Like we've done for get_user and put_user, ensure that user pointers
> are masked before invoking the underlying __arch_{clear,copy_*}_user
> operations.
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> [ v4.4: fixup for v4.4 style uaccess primitives ]
> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Reviewed-by: Mark Rutland <mark.rutland@arm.com> [v4.4 backport]

Mark.

> ---
>  arch/arm64/include/asm/uaccess.h | 18 ++++++++++--------
>  arch/arm64/kernel/arm64ksyms.c   |  4 ++--
>  arch/arm64/lib/clear_user.S      |  6 +++---
>  arch/arm64/lib/copy_in_user.S    |  4 ++--
>  4 files changed, 17 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 693a0d784534..f2f5a152f372 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -303,19 +303,18 @@ do {									\
>  
>  extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
>  extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
> -extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n);
> -extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n);
> +extern unsigned long __must_check __arch_copy_in_user(void __user *to, const void __user *from, unsigned long n);
>  
>  static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n)
>  {
>  	kasan_check_write(to, n);
> -	return  __arch_copy_from_user(to, from, n);
> +	return __arch_copy_from_user(to, __uaccess_mask_ptr(from), n);
>  }
>  
>  static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n)
>  {
>  	kasan_check_read(from, n);
> -	return  __arch_copy_to_user(to, from, n);
> +	return __arch_copy_to_user(__uaccess_mask_ptr(to), from, n);
>  }
>  
>  static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
> @@ -338,22 +337,25 @@ static inline unsigned long __must_check copy_to_user(void __user *to, const voi
>  	return n;
>  }
>  
> -static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n)
> +static inline unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n)
>  {
>  	if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n))
> -		n = __copy_in_user(to, from, n);
> +		n = __arch_copy_in_user(__uaccess_mask_ptr(to), __uaccess_mask_ptr(from), n);
>  	return n;
>  }
> +#define copy_in_user __copy_in_user
>  
>  #define __copy_to_user_inatomic __copy_to_user
>  #define __copy_from_user_inatomic __copy_from_user
>  
> -static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
> +extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
> +static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
>  {
>  	if (access_ok(VERIFY_WRITE, to, n))
> -		n = __clear_user(__uaccess_mask_ptr(to), n);
> +		n = __arch_clear_user(__uaccess_mask_ptr(to), n);
>  	return n;
>  }
> +#define clear_user	__clear_user
>  
>  extern long strncpy_from_user(char *dest, const char __user *src, long count);
>  
> diff --git a/arch/arm64/kernel/arm64ksyms.c b/arch/arm64/kernel/arm64ksyms.c
> index c654df05b7d7..abe4e0984dbb 100644
> --- a/arch/arm64/kernel/arm64ksyms.c
> +++ b/arch/arm64/kernel/arm64ksyms.c
> @@ -35,8 +35,8 @@ EXPORT_SYMBOL(clear_page);
>  	/* user mem (segment) */
>  EXPORT_SYMBOL(__arch_copy_from_user);
>  EXPORT_SYMBOL(__arch_copy_to_user);
> -EXPORT_SYMBOL(__clear_user);
> -EXPORT_SYMBOL(__copy_in_user);
> +EXPORT_SYMBOL(__arch_clear_user);
> +EXPORT_SYMBOL(__arch_copy_in_user);
>  
>  	/* physical memory */
>  EXPORT_SYMBOL(memstart_addr);
> diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
> index a9723c71c52b..fc6bb0f83511 100644
> --- a/arch/arm64/lib/clear_user.S
> +++ b/arch/arm64/lib/clear_user.S
> @@ -24,7 +24,7 @@
>  
>  	.text
>  
> -/* Prototype: int __clear_user(void *addr, size_t sz)
> +/* Prototype: int __arch_clear_user(void *addr, size_t sz)
>   * Purpose  : clear some user memory
>   * Params   : addr - user memory address to clear
>   *          : sz   - number of bytes to clear
> @@ -32,7 +32,7 @@
>   *
>   * Alignment fixed up by hardware.
>   */
> -ENTRY(__clear_user)
> +ENTRY(__arch_clear_user)
>  ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
>  	    CONFIG_ARM64_PAN)
>  	mov	x2, x1			// save the size for fixup return
> @@ -57,7 +57,7 @@ USER(9f, strb	wzr, [x0]	)
>  ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
>  	    CONFIG_ARM64_PAN)
>  	ret
> -ENDPROC(__clear_user)
> +ENDPROC(__arch_clear_user)
>  
>  	.section .fixup,"ax"
>  	.align	2
> diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
> index 81c8fc93c100..0219aa85b3cc 100644
> --- a/arch/arm64/lib/copy_in_user.S
> +++ b/arch/arm64/lib/copy_in_user.S
> @@ -67,7 +67,7 @@
>  	.endm
>  
>  end	.req	x5
> -ENTRY(__copy_in_user)
> +ENTRY(__arch_copy_in_user)
>  ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
>  	    CONFIG_ARM64_PAN)
>  	add	end, x0, x2
> @@ -76,7 +76,7 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
>  	    CONFIG_ARM64_PAN)
>  	mov	x0, #0
>  	ret
> -ENDPROC(__copy_in_user)
> +ENDPROC(__arch_copy_in_user)
>  
>  	.section .fixup,"ax"
>  	.align	2
> -- 
> 2.21.0.rc0.269.g1a574e7a288b
>