If unsure, say Y.
+config RODATA_FULL_DEFAULT_ENABLED
+ bool "Apply r/o permissions of VM areas also to their linear aliases"
+ default y
+ help
+ Apply read-only attributes of VM areas to the linear alias of
+ the backing pages as well. This prevents code or read-only data
+ from being modified (inadvertently or intentionally) via another
+ mapping of the same memory page. This additional enhancement can
+ be turned off at runtime by passing rodata=[off|on] (and turned on
+ with rodata=full if this option is set to 'n')
+
+ This requires the linear region to be mapped down to pages,
+ which may adversely affect performance in some cases.
+
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
depends on COMPAT
#include <asm/sysreg.h>
#include <asm/tlbflush.h>
+extern bool rodata_full;
+
static inline void contextidr_thread_switch(struct task_struct *next)
{
if (!IS_ENABLED(CONFIG_PID_IN_CONTEXTIDR))
struct memblock_region *reg;
int flags = 0;
- if (debug_pagealloc_enabled())
+ if (rodata_full || debug_pagealloc_enabled())
flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
/*
static int __init parse_rodata(char *arg)
{
- return strtobool(arg, &rodata_enabled);
+ int ret = strtobool(arg, &rodata_enabled);
+ if (!ret) {
+ rodata_full = false;
+ return 0;
+ }
+
+ /* permit 'full' in addition to boolean options */
+ if (strcmp(arg, "full"))
+ return -EINVAL;
+
+ rodata_enabled = true;
+ rodata_full = true;
+ return 0;
}
early_param("rodata", parse_rodata);
pgprot_t clear_mask;
};
+bool rodata_full __ro_after_init = IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED);
+
static int change_page_range(pte_t *ptep, pgtable_t token, unsigned long addr,
void *data)
{
unsigned long size = PAGE_SIZE*numpages;
unsigned long end = start + size;
struct vm_struct *area;
+ int i;
if (!PAGE_ALIGNED(addr)) {
start &= PAGE_MASK;
if (!numpages)
return 0;
+ /*
+ * If we are manipulating read-only permissions, apply the same
+ * change to the linear mapping of the pages that back this VM area.
+ */
+ if (rodata_full && (pgprot_val(set_mask) == PTE_RDONLY ||
+ pgprot_val(clear_mask) == PTE_RDONLY)) {
+ for (i = 0; i < area->nr_pages; i++) {
+ __change_memory_common((u64)page_address(area->pages[i]),
+ PAGE_SIZE, set_mask, clear_mask);
+ }
+ }
+
/*
* Get rid of potentially aliasing lazily unmapped vm areas that may
* have permissions set that deviate from the ones we are setting here.