From f47233c2d34f243ecdaac179c3408a39ff9216a7 Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Fri, 13 Feb 2015 16:04:55 +0100 Subject: x86/mm/ASLR: Propagate base load address calculation Commit: e2b32e678513 ("x86, kaslr: randomize module base load address") makes the base address for module to be unconditionally randomized in case when CONFIG_RANDOMIZE_BASE is defined and "nokaslr" option isn't present on the commandline. This is not consistent with how choose_kernel_location() decides whether it will randomize kernel load base. Namely, CONFIG_HIBERNATION disables kASLR (unless "kaslr" option is explicitly specified on kernel commandline), which makes the state space larger than what module loader is looking at. IOW CONFIG_HIBERNATION && CONFIG_RANDOMIZE_BASE is a valid config option, kASLR wouldn't be applied by default in that case, but module loader is not aware of that. Instead of fixing the logic in module.c, this patch takes more generic aproach. It introduces a new bootparam setup data_type SETUP_KASLR and uses that to pass the information whether kaslr has been applied during kernel decompression, and sets a global 'kaslr_enabled' variable accordingly, so that any kernel code (module loading, livepatching, ...) can make decisions based on its value. x86 module loader is converted to make use of this flag. Signed-off-by: Jiri Kosina Acked-by: Kees Cook Cc: "H. Peter Anvin" Link: https://lkml.kernel.org/r/alpine.LNX.2.00.1502101411280.10719@pobox.suse.cz [ Always dump correct kaslr status when panicking ] Signed-off-by: Borislav Petkov --- arch/x86/kernel/module.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) (limited to 'arch/x86/kernel/module.c') diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index e69f988..c3c59a3 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -32,6 +32,7 @@ #include #include +#include #if 0 #define DEBUGP(fmt, ...) \ @@ -46,21 +47,13 @@ do { \ #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) { + if (kaslr_enabled) { mutex_lock(&module_kaslr_mutex); /* * Calculate the module_load_offset the first time this -- cgit v1.1