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authorHendrik Brueckner <brueckner@linux.vnet.ibm.com>2010-11-10 10:05:55 +0100
committerMartin Schwidefsky <sky@mschwide.boeblingen.de.ibm.com>2010-11-10 10:05:54 +0100
commitec6743bb06510c7b629603ce35713d6ae9273579 (patch)
tree6faddd2ca7b991987bafc2a7d4241ad6d141b765 /arch/s390
parentca768b663131ca644689fcadc9ca092dcc96a758 (diff)
downloadlinux-linaro-stable-ec6743bb06510c7b629603ce35713d6ae9273579.tar.gz
[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: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/Kconfig.debug12
-rw-r--r--arch/s390/include/asm/page.h5
2 files changed, 17 insertions, 0 deletions
diff --git a/arch/s390/Kconfig.debug b/arch/s390/Kconfig.debug
index 45e0c6199f36..05221b13ffb1 100644
--- a/arch/s390/Kconfig.debug
+++ b/arch/s390/Kconfig.debug
@@ -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---
diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index a8729ea7e9ac..3c987e9ec8d6 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -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