2 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 7ab94c825b57..3bb991fd2b51 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -640,6 +640,14 @@ static int tun_chr_ioctl(struct inode *inode, struct file *file,
                 return 0;
         }
 
+        if (cmd == TUNGETFEATURES) {
+                /* Currently this just means: "what IFF flags are valid?".
+                 * 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,
+                                (unsigned int __user*)argp);
+        }
+
         if (!tun)
                 return -EBADFD;
 
diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 18f31b6187a3..94f76a112303 100644
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -40,6 +40,7 @@
 #define TUNSETOWNER   _IOW('T', 204, int)
 #define TUNSETLINK    _IOW('T', 205, int)
 #define TUNSETGROUP   _IOW('T', 206, int)
+#define TUNGETFEATURES _IOR('T', 207, unsigned int)
 
 /* TUNSETIFF ifr flags */
 #define IFF_TUN         0x0001