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Commit ec6743bb authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
Browse files

[S390] mm: add devmem_is_allowed() for STRICT_DEVMEM checking 



Provide the devmem_is_allowed() routine to restrict access to
kernel memory from userspace.
Set the CONFIG_STRICT_DEVMEM config option to switch on checking.

Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent ca768b66

arch/s390/Kconfig.debug

+12 −0
Original line number Diff line number Diff line
@@ -6,6 +6,18 @@ config TRACE_IRQFLAGS_SUPPORT 


source "lib/Kconfig.debug"



config STRICT_DEVMEM

	def_bool y

	prompt "Filter access to /dev/mem"

	---help---

	  This option restricts access to /dev/mem.  If this option is

	  disabled, you allow userspace access to all memory, including

	  kernel and userspace memory. Accidental memory access is likely

	  to be disastrous.

	  Memory access is required for experts who want to debug the kernel.



	  If you are unsure, say Y.



config DEBUG_STRICT_USER_COPY_CHECKS

	bool "Strict user copy size checks"

	---help---

arch/s390/include/asm/page.h

+5 −0
Original line number Diff line number Diff line
@@ -130,6 +130,11 @@ struct page; 
void arch_free_page(struct page *page, int order);

void arch_alloc_page(struct page *page, int order);



static inline int devmem_is_allowed(unsigned long pfn)

{

	return 0;

}



#define HAVE_ARCH_FREE_PAGE

#define HAVE_ARCH_ALLOC_PAGE