Commit 871402e0 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by Linus Torvalds
Browse files

mm: forbid splitting special mappings 

Don't allow splitting of vm_special_mapping's.  It affects vdso/vvar
areas.  Uprobes have only one page in xol_area so they aren't affected.

Those restrictions were enforced by checks in .mremap() callbacks.
Restrict resizing with generic .split() callback.

Link: https://lkml.kernel.org/r/20201013013416.390574-7-dima@arista.com


Signed-off-by: default avatarDmitry Safonov <dima@arista.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 73d5e062

arch/arm/kernel/vdso.c

+0 −9
Original line number Diff line number Diff line
@@ -50,15 +50,6 @@ static const struct vm_special_mapping vdso_data_mapping = { 
static int vdso_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;

	unsigned long vdso_size;



	/* without VVAR page */

	vdso_size = (vdso_total_pages - 1) << PAGE_SHIFT;



	if (vdso_size != new_size)

		return -EINVAL;



	current->mm->context.vdso = new_vma->vm_start;



	return 0;

arch/arm64/kernel/vdso.c

+3 −36
Original line number Diff line number Diff line
@@ -78,17 +78,9 @@ static union { 
} vdso_data_store __page_aligned_data;

struct vdso_data *vdso_data = vdso_data_store.data;



static int __vdso_remap(enum vdso_abi abi,

			const struct vm_special_mapping *sm,

static int vdso_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;

	unsigned long vdso_size = vdso_info[abi].vdso_code_end -

				  vdso_info[abi].vdso_code_start;



	if (vdso_size != new_size)

		return -EINVAL;



	current->mm->context.vdso = (void *)new_vma->vm_start;



	return 0;
@@ -219,17 +211,6 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, 
	return vmf_insert_pfn(vma, vmf->address, pfn);

}



static int vvar_mremap(const struct vm_special_mapping *sm,

		       struct vm_area_struct *new_vma)

{

	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;



	if (new_size != VVAR_NR_PAGES * PAGE_SIZE)

		return -EINVAL;



	return 0;

}



static int __setup_additional_pages(enum vdso_abi abi,

				    struct mm_struct *mm,

				    struct linux_binprm *bprm,
@@ -280,12 +261,6 @@ static int __setup_additional_pages(enum vdso_abi abi, 
/*

 * Create and map the vectors page for AArch32 tasks.

 */

static int aarch32_vdso_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	return __vdso_remap(VDSO_ABI_AA32, sm, new_vma);

}



enum aarch32_map {

	AA32_MAP_VECTORS, /* kuser helpers */

	AA32_MAP_SIGPAGE,
@@ -308,11 +283,10 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { 
	[AA32_MAP_VVAR] = {

		.name = "[vvar]",

		.fault = vvar_fault,

		.mremap = vvar_mremap,

	},

	[AA32_MAP_VDSO] = {

		.name = "[vdso]",

		.mremap = aarch32_vdso_mremap,

		.mremap = vdso_mremap,

	},

};
@@ -453,12 +427,6 @@ int aarch32_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) 
}

#endif /* CONFIG_COMPAT */



static int vdso_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	return __vdso_remap(VDSO_ABI_AA64, sm, new_vma);

}



enum aarch64_map {

	AA64_MAP_VVAR,

	AA64_MAP_VDSO,
@@ -468,7 +436,6 @@ static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { 
	[AA64_MAP_VVAR] = {

		.name	= "[vvar]",

		.fault = vvar_fault,

		.mremap = vvar_mremap,

	},

	[AA64_MAP_VDSO] = {

		.name	= "[vdso]",

arch/mips/vdso/genvdso.c

+0 −4
Original line number Diff line number Diff line
@@ -263,10 +263,6 @@ int main(int argc, char **argv) 
	fprintf(out_file, "	const struct vm_special_mapping *sm,\n");

	fprintf(out_file, "	struct vm_area_struct *new_vma)\n");

	fprintf(out_file, "{\n");

	fprintf(out_file, "	unsigned long new_size =\n");

	fprintf(out_file, "	new_vma->vm_end - new_vma->vm_start;\n");

	fprintf(out_file, "	if (vdso_image.size != new_size)\n");

	fprintf(out_file, "		return -EINVAL;\n");

	fprintf(out_file, "	current->mm->context.vdso =\n");

	fprintf(out_file, "	(void *)(new_vma->vm_start);\n");

	fprintf(out_file, "	return 0;\n");

arch/s390/kernel/vdso.c

+1 −10
Original line number Diff line number Diff line
@@ -61,17 +61,8 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm, 
static int vdso_mremap(const struct vm_special_mapping *sm,

		       struct vm_area_struct *vma)

{

	unsigned long vdso_pages;



	vdso_pages = vdso64_pages;



	if ((vdso_pages << PAGE_SHIFT) != vma->vm_end - vma->vm_start)

		return -EINVAL;



	if (WARN_ON_ONCE(current->mm != vma->vm_mm))

		return -EFAULT;



	current->mm->context.vdso_base = vma->vm_start;



	return 0;

}

arch/x86/entry/vdso/vma.c

+0 −17
Original line number Diff line number Diff line
@@ -89,30 +89,14 @@ static void vdso_fix_landing(const struct vdso_image *image, 
static int vdso_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;

	const struct vdso_image *image = current->mm->context.vdso_image;



	if (image->size != new_size)

		return -EINVAL;



	vdso_fix_landing(image, new_vma);

	current->mm->context.vdso = (void __user *)new_vma->vm_start;



	return 0;

}



static int vvar_mremap(const struct vm_special_mapping *sm,

		struct vm_area_struct *new_vma)

{

	const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;

	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;



	if (new_size != -image->sym_vvar_start)

		return -EINVAL;



	return 0;

}



#ifdef CONFIG_TIME_NS

static struct page *find_timens_vvar_page(struct vm_area_struct *vma)

{
@@ -252,7 +236,6 @@ static const struct vm_special_mapping vdso_mapping = { 
static const struct vm_special_mapping vvar_mapping = {

	.name = "[vvar]",

	.fault = vvar_fault,

	.mremap = vvar_mremap,

};



/*