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authorArjan van de Ven <arjan@linux.intel.com>2008-04-24 23:40:47 +0200
committerIngo Molnar <mingo@elte.hu>2008-04-24 23:40:47 +0200
commitae531c26c5c2a28ca1b35a75b39b3b256850f2c8 (patch)
treee4c2f3ec25bdb0e2e5f7f15f79a60c3175f03718 /include/asm-x86/page.h
parent94bc891b00e40cbec375feb4568780af183fd7f4 (diff)
downloadtalos-op-linux-ae531c26c5c2a28ca1b35a75b39b3b256850f2c8.tar.gz
talos-op-linux-ae531c26c5c2a28ca1b35a75b39b3b256850f2c8.zip
x86: introduce /dev/mem restrictions with a config option
This patch introduces a restriction on /dev/mem: Only non-memory can be read or written unless the newly introduced config option is set. The X server needs access to /dev/mem for the PCI space, but it doesn't need access to memory; both the file permissions and SELinux permissions of /dev/mem just make X effectively super-super powerful. With the exception of the BIOS area, there's just no valid app that uses /dev/mem on actual memory. Other popular users of /dev/mem are rootkits and the like. (note: mmap access of memory via /dev/mem was already not allowed since a really long time) People who want to use /dev/mem for kernel debugging can enable the config option. The restrictions of this patch have been in the Fedora and RHEL kernels for at least 4 years without any problems. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/asm-x86/page.h')
-rw-r--r--include/asm-x86/page.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/asm-x86/page.h b/include/asm-x86/page.h
index 6724a4bc6b7a..b381f4a5a0bd 100644
--- a/include/asm-x86/page.h
+++ b/include/asm-x86/page.h
@@ -47,6 +47,7 @@
#ifndef __ASSEMBLY__
extern int page_is_ram(unsigned long pagenr);
+extern int devmem_is_allowed(unsigned long pagenr);
extern unsigned long max_pfn_mapped;
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