From ec6743bb06510c7b629603ce35713d6ae9273579 Mon Sep 17 00:00:00 2001 From: Hendrik Brueckner Date: Wed, 10 Nov 2010 10:05:55 +0100 Subject: [PATCH] [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 Signed-off-by: Martin Schwidefsky --- arch/s390/Kconfig.debug | 12 ++++++++++++ arch/s390/include/asm/page.h | 5 +++++ 2 files changed, 17 insertions(+) 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 -- 2.11.0