tuntap: add ioctl to attach or detach a file form tuntap device

Sometimes usespace may need to active/deactive a queue, this could be done by
detaching and attaching a file from tuntap device.

This patch introduces a new ioctls - TUNSETQUEUE which could be used to do
this. Flag IFF_ATTACH_QUEUE were introduced to do attaching while
IFF_DETACH_QUEUE were introduced to do the detaching.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 2762c55aeb6692d5adb746b92beb0c160c19f37c..79b6f9ecc12cc5a07341591b307e41a7155afefc 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -195,6 +195,15 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
        return txq;
 }
 
+static inline bool tun_not_capable(struct tun_struct *tun)
+{
+       const struct cred *cred = current_cred();
+
+       return ((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
+                 (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
+               !capable(CAP_NET_ADMIN);
+}
+
 static void tun_set_real_num_queues(struct tun_struct *tun)
 {
        netif_set_real_num_tx_queues(tun->dev, tun->numqueues);
@@ -1310,8 +1319,6 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
 
        dev = __dev_get_by_name(net, ifr->ifr_name);
        if (dev) {
-               const struct cred *cred = current_cred();
-
                if (ifr->ifr_flags & IFF_TUN_EXCL)
                        return -EBUSY;
                if ((ifr->ifr_flags & IFF_TUN) && dev->netdev_ops == &tun_netdev_ops)
@@ -1321,9 +1328,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                else
                        return -EINVAL;
 
-               if (((uid_valid(tun->owner) && !uid_eq(cred->euid, tun->owner)) ||
-                    (gid_valid(tun->group) && !in_egroup_p(tun->group))) &&
-                   !capable(CAP_NET_ADMIN))
+               if (tun_not_capable(tun))
                        return -EPERM;
                err = security_tun_dev_attach(tfile->socket.sk);
                if (err < 0)
@@ -1530,6 +1535,40 @@ static void tun_set_sndbuf(struct tun_struct *tun)
        }
 }
 
+static int tun_set_queue(struct file *file, struct ifreq *ifr)
+{
+       struct tun_file *tfile = file->private_data;
+       struct tun_struct *tun;
+       struct net_device *dev;
+       int ret = 0;
+
+       rtnl_lock();
+
+       if (ifr->ifr_flags & IFF_ATTACH_QUEUE) {
+               dev = __dev_get_by_name(tfile->net, ifr->ifr_name);
+               if (!dev) {
+                       ret = -EINVAL;
+                       goto unlock;
+               }
+
+               tun = netdev_priv(dev);
+               if (dev->netdev_ops != &tap_netdev_ops &&
+                       dev->netdev_ops != &tun_netdev_ops)
+                       ret = -EINVAL;
+               else if (tun_not_capable(tun))
+                       ret = -EPERM;
+               else
+                       ret = tun_attach(tun, file);
+       } else if (ifr->ifr_flags & IFF_DETACH_QUEUE)
+               __tun_detach(tfile, false);
+       else
+               ret = -EINVAL;
+
+unlock:
+       rtnl_unlock();
+       return ret;
+}
+
 static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg, int ifreq_len)
 {
@@ -1543,7 +1582,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
        int vnet_hdr_sz;
        int ret;
 
-       if (cmd == TUNSETIFF || _IOC_TYPE(cmd) == 0x89) {
+       if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == 0x89) {
                if (copy_from_user(&ifr, argp, ifreq_len))
                        return -EFAULT;
        } else {
@@ -1554,9 +1593,10 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
                 * This is needed because we never checked for invalid flags on
                 * TUNSETIFF. */
                return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
-                               IFF_VNET_HDR,
+                               IFF_VNET_HDR | IFF_MULTI_QUEUE,
                                (unsigned int __user*)argp);
-       }
+       } else if (cmd == TUNSETQUEUE)
+               return tun_set_queue(file, &ifr);
 
        ret = 0;
        rtnl_lock();

diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index 8ef3a87b58a0e317e260fba50236a7198ad77deb..958497ad5bb563f40c6a46cf7e8aac951ef98d36 100644 (file)
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -54,6 +54,7 @@
 #define TUNDETACHFILTER _IOW('T', 214, struct sock_fprog)
 #define TUNGETVNETHDRSZ _IOR('T', 215, int)
 #define TUNSETVNETHDRSZ _IOW('T', 216, int)
+#define TUNSETQUEUE  _IOW('T', 217, int)
 
 /* TUNSETIFF ifr flags */
 #define IFF_TUN                0x0001
@@ -63,6 +64,8 @@
 #define IFF_VNET_HDR   0x4000
 #define IFF_TUN_EXCL   0x8000
 #define IFF_MULTI_QUEUE 0x0100
+#define IFF_ATTACH_QUEUE 0x0200
+#define IFF_DETACH_QUEUE 0x0400
 
 /* Features for GSO (TUNSETOFFLOAD). */
 #define TUN_F_CSUM     0x01    /* You can hand me unchecksummed packets. */