Commit c462ac28 authored by Catalin Marinas's avatar Catalin Marinas
Browse files

mm: Introduce arch_validate_flags() 



Similarly to arch_validate_prot() called from do_mprotect_pkey(), an
architecture may need to sanity-check the new vm_flags.

Define a dummy function always returning true. In addition to
do_mprotect_pkey(), also invoke it from mmap_region() prior to updating
vma->vm_page_prot to allow the architecture code to veto potentially
inconsistent vm_flags.

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 9f341931

include/linux/mman.h

+13 −0
Original line number Diff line number Diff line
@@ -108,6 +108,19 @@ static inline bool arch_validate_prot(unsigned long prot, unsigned long addr) 
#define arch_validate_prot arch_validate_prot

#endif



#ifndef arch_validate_flags

/*

 * This is called from mmap() and mprotect() with the updated vma->vm_flags.

 *

 * Returns true if the VM_* flags are valid.

 */

static inline bool arch_validate_flags(unsigned long flags)

{

	return true;

}

#define arch_validate_flags arch_validate_flags

#endif



/*

 * Optimisation macro.  It is equivalent to:

 *      (x & bit1) ? bit2 : 0

mm/mmap.c

+9 −0
Original line number Diff line number Diff line
@@ -1812,6 +1812,15 @@ unsigned long mmap_region(struct file *file, unsigned long addr, 
		vma_set_anonymous(vma);

	}



	/* Allow architectures to sanity-check the vm_flags */

	if (!arch_validate_flags(vma->vm_flags)) {

		error = -EINVAL;

		if (file)

			goto unmap_and_free_vma;

		else

			goto free_vma;

	}



	vma_link(mm, vma, prev, rb_link, rb_parent);

	/* Once vma denies write, undo our temporary denial count */

	if (file) {

mm/mprotect.c

+6 −0
Original line number Diff line number Diff line
@@ -603,6 +603,12 @@ static int do_mprotect_pkey(unsigned long start, size_t len, 
			goto out;

		}



		/* Allow architectures to sanity-check the new flags */

		if (!arch_validate_flags(newflags)) {

			error = -EINVAL;

			goto out;

		}



		error = security_file_mprotect(vma, reqprot, prot);

		if (error)

			goto out;

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