static long privcmd_ioctl_dm_op()

in privcmd.c [615:701]

• 70 lines of code
• 15 McCabe index (conditional complexity)

static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
{
	struct privcmd_data *data = file->private_data;
	struct privcmd_dm_op kdata;
	struct privcmd_dm_op_buf *kbufs;
	unsigned int nr_pages = 0;
	struct page **pages = NULL;
	struct xen_dm_op_buf *xbufs = NULL;
	unsigned int i;
	long rc;
	unsigned int pinned = 0;

	if (copy_from_user(&kdata, udata, sizeof(kdata)))
		return -EFAULT;

	/* If restriction is in place, check the domid matches */
	if (data->domid != DOMID_INVALID && data->domid != kdata.dom)
		return -EPERM;

	if (kdata.num == 0)
		return 0;

	if (kdata.num > privcmd_dm_op_max_num)
		return -E2BIG;

	kbufs = kcalloc(kdata.num, sizeof(*kbufs), GFP_KERNEL);
	if (!kbufs)
		return -ENOMEM;

	if (copy_from_user(kbufs, kdata.ubufs,
			   sizeof(*kbufs) * kdata.num)) {
		rc = -EFAULT;
		goto out;
	}

	for (i = 0; i < kdata.num; i++) {
		if (kbufs[i].size > privcmd_dm_op_buf_max_size) {
			rc = -E2BIG;
			goto out;
		}

		if (!access_ok(kbufs[i].uptr,
			       kbufs[i].size)) {
			rc = -EFAULT;
			goto out;
		}

		nr_pages += DIV_ROUND_UP(
			offset_in_page(kbufs[i].uptr) + kbufs[i].size,
			PAGE_SIZE);
	}

	pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
	if (!pages) {
		rc = -ENOMEM;
		goto out;
	}

	xbufs = kcalloc(kdata.num, sizeof(*xbufs), GFP_KERNEL);
	if (!xbufs) {
		rc = -ENOMEM;
		goto out;
	}

	rc = lock_pages(kbufs, kdata.num, pages, nr_pages, &pinned);
	if (rc < 0) {
		nr_pages = pinned;
		goto out;
	}

	for (i = 0; i < kdata.num; i++) {
		set_xen_guest_handle(xbufs[i].h, kbufs[i].uptr);
		xbufs[i].size = kbufs[i].size;
	}

	xen_preemptible_hcall_begin();
	rc = HYPERVISOR_dm_op(kdata.dom, kdata.num, xbufs);
	xen_preemptible_hcall_end();

out:
	unlock_pages(pages, nr_pages);
	kfree(xbufs);
	kfree(pages);
	kfree(kbufs);

	return rc;
}