path: root/init
diff options
authorLinus Torvalds <>2016-03-14 16:58:50 -0700
committerLinus Torvalds <>2016-03-14 16:58:50 -0700
commitd09e356ad06a8b6f5cceabf7c6cf05fdb62b46e5 (patch)
tree12db95262870c6ca3279b40e9f7c219d477c863d /init
parent5ec942463bfbc6c98ea4a96689b498e88a031c4a (diff)
parent11bf9b865898961cee60a41c483c9f27ec76e12e (diff)
Merge branch 'mm-readonly-for-linus' of git://
Pull read-only kernel memory updates from Ingo Molnar: "This tree adds two (security related) enhancements to the kernel's handling of read-only kernel memory: - extend read-only kernel memory to a new class of formerly writable kernel data: 'post-init read-only memory' via the __ro_after_init attribute, and mark the ARM and x86 vDSO as such read-only memory. This kind of attribute can be used for data that requires a once per bootup initialization sequence, but is otherwise never modified after that point. This feature was based on the work by PaX Team and Brad Spengler. (by Kees Cook, the ARM vDSO bits by David Brown.) - make CONFIG_DEBUG_RODATA always enabled on x86 and remove the Kconfig option. This simplifies the kernel and also signals that read-only memory is the default model and a first-class citizen. (Kees Cook)" * 'mm-readonly-for-linus' of git:// ARM/vdso: Mark the vDSO code read-only after init x86/vdso: Mark the vDSO code read-only after init lkdtm: Verify that '__ro_after_init' works correctly arch: Introduce post-init read-only memory x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings asm-generic: Consolidate mark_rodata_ro()
Diffstat (limited to 'init')
1 files changed, 23 insertions, 4 deletions
diff --git a/init/main.c b/init/main.c
index b3008bcfb1dc..7c27de4577ed 100644
--- a/init/main.c
+++ b/init/main.c
@@ -93,9 +93,6 @@ static int kernel_init(void *);
extern void init_IRQ(void);
extern void fork_init(void);
extern void radix_tree_init(void);
-static inline void mark_rodata_ro(void) { }
* Debug helper: via this flag we know that we are in 'early bootup code'
@@ -924,6 +921,28 @@ static int try_to_run_init_process(const char *init_filename)
static noinline void __init kernel_init_freeable(void);
+static bool rodata_enabled = true;
+static int __init set_debug_rodata(char *str)
+ return strtobool(str, &rodata_enabled);
+__setup("rodata=", set_debug_rodata);
+static void mark_readonly(void)
+ if (rodata_enabled)
+ mark_rodata_ro();
+ else
+ pr_info("Kernel memory protection disabled.\n");
+static inline void mark_readonly(void)
+ pr_warn("This architecture does not have kernel memory protection.\n");
static int __ref kernel_init(void *unused)
int ret;
@@ -932,7 +951,7 @@ static int __ref kernel_init(void *unused)
/* need to finish all async __init code before freeing the memory */
- mark_rodata_ro();
+ mark_readonly();
system_state = SYSTEM_RUNNING;