Commit 1dcec254 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

[S390] uaccess: implement strict user copy checks 



Same as on x86 and sparc, besides the fact that enabling the option
will just emit compile time warnings instead of errors.
Keeps allyesconfig kernels compiling.

Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 68c6b859

arch/s390/Kconfig.debug

+13 −0
Original line number Diff line number Diff line
@@ -6,4 +6,17 @@ config TRACE_IRQFLAGS_SUPPORT 


source "lib/Kconfig.debug"



config DEBUG_STRICT_USER_COPY_CHECKS

	bool "Strict user copy size checks"

	---help---

	  Enabling this option turns a certain set of sanity checks for user

	  copy operations into compile time warnings.



	  The copy_from_user() etc checks are there to help test if there

	  are sufficient security checks on the length argument of

	  the copy operation, by having gcc prove that the argument is

	  within bounds.



	  If unsure, or if you run an older (pre 4.4) gcc, say N.



endmenu

arch/s390/include/asm/uaccess.h

+12 −0
Original line number Diff line number Diff line
@@ -265,6 +265,12 @@ __copy_from_user(void *to, const void __user *from, unsigned long n) 
		return uaccess.copy_from_user(n, from, to);

}



extern void copy_from_user_overflow(void)

#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

__compiletime_warning("copy_from_user() buffer size is not provably correct")

#endif

;



/**

 * copy_from_user: - Copy a block of data from user space.

 * @to:   Destination address, in kernel space.
@@ -284,7 +290,13 @@ __copy_from_user(void *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)

{

	unsigned int sz = __compiletime_object_size(to);



	might_fault();

	if (unlikely(sz != -1 && sz < n)) {

		copy_from_user_overflow();

		return n;

	}

	if (access_ok(VERIFY_READ, from, n))

		n = __copy_from_user(to, from, n);

	else

arch/s390/lib/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
# Makefile for s390-specific library files..

#



lib-y += delay.o string.o uaccess_std.o uaccess_pt.o

lib-y += delay.o string.o uaccess_std.o uaccess_pt.o usercopy.o

obj-$(CONFIG_32BIT) += div64.o qrnnd.o ucmpdi2.o

lib-$(CONFIG_64BIT) += uaccess_mvcos.o

lib-$(CONFIG_SMP) += spinlock.o

arch/s390/lib/usercopy.c

0 → 100644
+8 −0
Original line number Diff line number Diff line 
#include <linux/module.h>

#include <linux/bug.h>



void copy_from_user_overflow(void)

{

	WARN(1, "Buffer overflow detected!\n");

}

EXPORT_SYMBOL(copy_from_user_overflow);