Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / arch / x86 / kernel / module.c

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 18be189..e69f988 100644 (file)
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -28,6 +28,7 @@
 #include <linux/mm.h>
 #include <linux/gfp.h>
 #include <linux/jump_label.h>
+#include <linux/random.h>
 
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -43,13 +44,52 @@ do {                                                        \
 } while (0)
 #endif
 
+#ifdef CONFIG_RANDOMIZE_BASE
+static unsigned long module_load_offset;
+static int randomize_modules = 1;
+
+/* Mutex protects the module_load_offset. */
+static DEFINE_MUTEX(module_kaslr_mutex);
+
+static int __init parse_nokaslr(char *p)
+{
+       randomize_modules = 0;
+       return 0;
+}
+early_param("nokaslr", parse_nokaslr);
+
+static unsigned long int get_module_load_offset(void)
+{
+       if (randomize_modules) {
+               mutex_lock(&module_kaslr_mutex);
+               /*
+                * Calculate the module_load_offset the first time this
+                * code is called. Once calculated it stays the same until
+                * reboot.
+                */
+               if (module_load_offset == 0)
+                       module_load_offset =
+                               (get_random_int() % 1024 + 1) * PAGE_SIZE;
+               mutex_unlock(&module_kaslr_mutex);
+       }
+       return module_load_offset;
+}
+#else
+static unsigned long int get_module_load_offset(void)
+{
+       return 0;
+}
+#endif
+
 void *module_alloc(unsigned long size)
 {
        if (PAGE_ALIGN(size) > MODULES_LEN)
                return NULL;
-       return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
-                               GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
-                               NUMA_NO_NODE, __builtin_return_address(0));
+       return __vmalloc_node_range(size, 1,
+                                   MODULES_VADDR + get_module_load_offset(),
+                                   MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
+                                   PAGE_KERNEL_EXEC, NUMA_NO_NODE,
+                                   __builtin_return_address(0));
 }
 
 #ifdef CONFIG_X86_32