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Commit 08925c2f authored by Laura Abbott's avatar Laura Abbott Committed by Russell King
Browse files

ARM: 8464/1: Update all mm structures with section adjustments 



Currently, when updating section permissions to mark areas RO
or NX, the only mm updated is current->mm. This is working off
the assumption that there are no additional mm structures at
the time. This may not always hold true. (Example: calling
modprobe early will trigger a fork/exec). Ensure all mm structres
get updated with the new section information.

Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarLaura Abbott <labbott@fedoraproject.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 40ee068e

arch/arm/mm/init.c

+62 −30
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/memblock.h>

#include <linux/dma-contiguous.h>

#include <linux/sizes.h>

#include <linux/stop_machine.h>



#include <asm/cp15.h>

#include <asm/mach-types.h>
@@ -627,12 +628,10 @@ static struct section_perm ro_perms[] = { 
 * safe to be called with preemption disabled, as under stop_machine().

 */

static inline void section_update(unsigned long addr, pmdval_t mask,

				  pmdval_t prot)

				  pmdval_t prot, struct mm_struct *mm)

{

	struct mm_struct *mm;

	pmd_t *pmd;



	mm = current->active_mm;

	pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr);



#ifdef CONFIG_ARM_LPAE
@@ -656,49 +655,82 @@ static inline bool arch_has_strict_perms(void) 
	return !!(get_cr() & CR_XP);

}



#define set_section_perms(perms, field)	{				\

	size_t i;							\

	unsigned long addr;						\

									\

	if (!arch_has_strict_perms())					\

		return;							\

									\

	for (i = 0; i < ARRAY_SIZE(perms); i++) {			\

		if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) ||	\

		    !IS_ALIGNED(perms[i].end, SECTION_SIZE)) {		\

			pr_err("BUG: section %lx-%lx not aligned to %lx\n", \

				perms[i].start, perms[i].end,		\

				SECTION_SIZE);				\

			continue;					\

		}							\

									\

		for (addr = perms[i].start;				\

		     addr < perms[i].end;				\

		     addr += SECTION_SIZE)				\

			section_update(addr, perms[i].mask,		\

				       perms[i].field);			\

	}								\

void set_section_perms(struct section_perm *perms, int n, bool set,

			struct mm_struct *mm)

{

	size_t i;

	unsigned long addr;



	if (!arch_has_strict_perms())

		return;



	for (i = 0; i < n; i++) {

		if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) ||

		    !IS_ALIGNED(perms[i].end, SECTION_SIZE)) {

			pr_err("BUG: section %lx-%lx not aligned to %lx\n",

				perms[i].start, perms[i].end,

				SECTION_SIZE);

			continue;

		}



		for (addr = perms[i].start;

		     addr < perms[i].end;

		     addr += SECTION_SIZE)

			section_update(addr, perms[i].mask,

				set ? perms[i].prot : perms[i].clear, mm);

	}



}



static inline void fix_kernmem_perms(void)

static void update_sections_early(struct section_perm perms[], int n)

{

	set_section_perms(nx_perms, prot);

	struct task_struct *t, *s;



	read_lock(&tasklist_lock);

	for_each_process(t) {

		if (t->flags & PF_KTHREAD)

			continue;

		for_each_thread(t, s)

			set_section_perms(perms, n, true, s->mm);

	}

	read_unlock(&tasklist_lock);

	set_section_perms(perms, n, true, current->active_mm);

	set_section_perms(perms, n, true, &init_mm);

}



int __fix_kernmem_perms(void *unused)

{

	update_sections_early(nx_perms, ARRAY_SIZE(nx_perms));

	return 0;

}



void fix_kernmem_perms(void)

{

	stop_machine(__fix_kernmem_perms, NULL, NULL);

}



#ifdef CONFIG_DEBUG_RODATA

int __mark_rodata_ro(void *unused)

{

	update_sections_early(ro_perms, ARRAY_SIZE(ro_perms));

	return 0;

}



void mark_rodata_ro(void)

{

	set_section_perms(ro_perms, prot);

	stop_machine(__mark_rodata_ro, NULL, NULL);

}



void set_kernel_text_rw(void)

{

	set_section_perms(ro_perms, clear);

	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), false,

				current->active_mm);

}



void set_kernel_text_ro(void)

{

	set_section_perms(ro_perms, prot);

	set_section_perms(ro_perms, ARRAY_SIZE(ro_perms), true,

				current->active_mm);

}

#endif /* CONFIG_DEBUG_RODATA */