atm: 32-bit ioctl compatibility

We lack compat ioctl support through most of the ATM code. This patch
deals with most of it, and I can now at least use BR2684 and PPPoATM
with 32-bit userspace.

I haven't added a .compat_ioctl method to struct atm_ioctl, because
AFAICT none of the current users need any conversion -- so we can just
call the ->ioctl() method in every case. I looked at br2684, clip, lec,
mpc, pppoatm and atmtcp.

In svc_compat_ioctl() the only mangling which is needed is to change
COMPAT_ATM_ADDPARTY to ATM_ADDPARTY. Although it's defined as
	_IOW('a', ATMIOC_SPECIAL+4,struct atm_iobuf)
it doesn't actually _take_ a struct atm_iobuf as an argument -- it takes
a struct sockaddr_atmsvc, which _is_ the same between 32-bit and 64-bit
code, so doesn't need conversion.

Almost all of vcc_ioctl() would have been identical, so I converted that
into a core do_vcc_ioctl() function with an 'int compat' argument.

I've done the same with atm_dev_ioctl(), where there _are_ a few
differences, but still it's relatively contained and there would
otherwise have been a lot of duplication.

I haven't done any of the actual device-specific ioctls, although I've
added a compat_ioctl method to struct atmdev_ops.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/atm/resources.c

@@ -195,20 +195,39 @@ static int fetch_stats(struct atm_dev *dev, struct atm_dev_stats __user *arg, in
 }
 
 
-int atm_dev_ioctl(unsigned int cmd, void __user *arg)
+int atm_dev_ioctl(unsigned int cmd, void __user *arg, int compat)
 {
 	void __user *buf;
 	int error, len, number, size = 0;
 	struct atm_dev *dev;
 	struct list_head *p;
 	int *tmp_buf, *tmp_p;
-	struct atm_iobuf __user *iobuf = arg;
-	struct atmif_sioc __user *sioc = arg;
+	int __user *sioc_len;
+	int __user *iobuf_len;
+
+#ifndef CONFIG_COMPAT
+	compat = 0; /* Just so the compiler _knows_ */
+#endif
+
 	switch (cmd) {
 		case ATM_GETNAMES:
-			if (get_user(buf, &iobuf->buffer))
-				return -EFAULT;
-			if (get_user(len, &iobuf->length))
+
+			if (compat) {
+#ifdef CONFIG_COMPAT
+				struct compat_atm_iobuf __user *ciobuf = arg;
+				compat_uptr_t cbuf;
+				iobuf_len = &ciobuf->length;
+				if (get_user(cbuf, &ciobuf->buffer))
+					return -EFAULT;
+				buf = compat_ptr(cbuf);
+#endif
+			} else {
+				struct atm_iobuf __user *iobuf = arg;
+				iobuf_len = &iobuf->length;
+				if (get_user(buf, &iobuf->buffer))
+					return -EFAULT;
+			}
+			if (get_user(len, iobuf_len))
 				return -EFAULT;
 			mutex_lock(&atm_dev_mutex);
 			list_for_each(p, &atm_devs)
@@ -229,7 +248,7 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
 			}
 			mutex_unlock(&atm_dev_mutex);
 			error = ((copy_to_user(buf, tmp_buf, size)) ||
-					put_user(size, &iobuf->length))
+					put_user(size, iobuf_len))
 						? -EFAULT : 0;
 			kfree(tmp_buf);
 			return error;
@@ -237,13 +256,32 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
 			break;
 	}
 
-	if (get_user(buf, &sioc->arg))
-		return -EFAULT;
-	if (get_user(len, &sioc->length))
-		return -EFAULT;
-	if (get_user(number, &sioc->number))
-		return -EFAULT;
+	if (compat) {
+#ifdef CONFIG_COMPAT
+		struct compat_atmif_sioc __user *csioc = arg;
+		compat_uptr_t carg;
 
+		sioc_len = &csioc->length;
+		if (get_user(carg, &csioc->arg))
+			return -EFAULT;
+		buf = compat_ptr(carg);
+
+		if (get_user(len, &csioc->length))
+			return -EFAULT;
+		if (get_user(number, &csioc->number))
+			return -EFAULT;
+#endif
+	} else {
+		struct atmif_sioc __user *sioc = arg;
+
+		sioc_len = &sioc->length;
+		if (get_user(buf, &sioc->arg))
+			return -EFAULT;
+		if (get_user(len, &sioc->length))
+			return -EFAULT;
+		if (get_user(number, &sioc->number))
+			return -EFAULT;
+	}
 	if (!(dev = try_then_request_module(atm_dev_lookup(number),
 					    "atm-device-%d", number)))
 		return -ENODEV;
@@ -358,7 +396,7 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
 			size = error;
 			/* may return 0, but later on size == 0 means "don't
 			   write the length" */
-			error = put_user(size, &sioc->length)
+			error = put_user(size, sioc_len)
 				? -EFAULT : 0;
 			goto done;
 		case ATM_SETLOOP:
@@ -380,11 +418,21 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
 			}
 			/* fall through */
 		default:
-			if (!dev->ops->ioctl) {
-				error = -EINVAL;
-				goto done;
+			if (compat) {
+#ifdef CONFIG_COMPAT
+				if (!dev->ops->compat_ioctl) {
+					error = -EINVAL;
+					goto done;
+				}
+				size = dev->ops->compat_ioctl(dev, cmd, buf);
+#endif
+			} else {
+				if (!dev->ops->ioctl) {
+					error = -EINVAL;
+					goto done;
+				}
+				size = dev->ops->ioctl(dev, cmd, buf);
 			}
-			size = dev->ops->ioctl(dev, cmd, buf);
 			if (size < 0) {
 				error = (size == -ENOIOCTLCMD ? -EINVAL : size);
 				goto done;
@@ -392,7 +440,7 @@ int atm_dev_ioctl(unsigned int cmd, void __user *arg)
 	}
 
 	if (size)
-		error = put_user(size, &sioc->length)
+		error = put_user(size, sioc_len)
 			? -EFAULT : 0;
 	else
 		error = 0;