Merge "staging: android: ashmem: Disallow ashmem memory from being remapped" (9697173f) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/staging/android/ashmem.c

+28 −0

Original line number	Diff line number	Diff line
		@@ -350,8 +350,23 @@ static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
		_calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
		}

		static int ashmem_vmfile_mmap(struct file file, struct vm_area_struct vma)
		{
		/* do not allow to mmap ashmem backing shmem file directly */
		return -EPERM;
		}

		static unsigned long
		ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr,
		unsigned long len, unsigned long pgoff,
		unsigned long flags)
		{
		return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
		}

		static int ashmem_mmap(struct file file, struct vm_area_struct vma)
		{
		static struct file_operations vmfile_fops;
		struct ashmem_area *asma = file->private_data;
		int ret = 0;

		@@ -392,6 +407,19 @@ static int ashmem_mmap(struct file file, struct vm_area_struct vma)
		}
		vmfile->f_mode \|= FMODE_LSEEK;
		asma->file = vmfile;
		/*
		* override mmap operation of the vmfile so that it can't be
		* remapped which would lead to creation of a new vma with no
		* asma permission checks. Have to override get_unmapped_area
		* as well to prevent VM_BUG_ON check for f_ops modification.
		*/
		if (!vmfile_fops.mmap) {
		vmfile_fops = *vmfile->f_op;
		vmfile_fops.mmap = ashmem_vmfile_mmap;
		vmfile_fops.get_unmapped_area =
		ashmem_vmfile_get_unmapped_area;
		}
		vmfile->f_op = &vmfile_fops;
		}
		get_file(asma->file);