This patch introduces new ioctl for change packet steering policy for
tun. Only automatic flow steering is supported, more policies will
come.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 drivers/net/tun.c           | 35 ++++++++++++++++++++++++++++++++++-
 include/uapi/linux/if_tun.h |  7 +++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index bff6259..ab109ff 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c

@@ -122,7 +122,8 @@ do {                                                                \
 #define TUN_VNET_BE     0x40000000

 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
-                     IFF_MULTI_QUEUE | IFF_NAPI | IFF_NAPI_FRAGS)
+                     IFF_MULTI_QUEUE | IFF_NAPI | IFF_NAPI_FRAGS | \
+                     IFF_MULTI_STEERING)

 #define GOODCOPY_LEN 128

@@ -2516,6 +2517,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
        unsigned int ifindex;
        int le;
        int ret;
+       unsigned int steering;

        if (cmd == TUNSETIFF || cmd == TUNSETQUEUE || _IOC_TYPE(cmd) == SOCK_IOC_TYPE) {
                if (copy_from_user(&ifr, argp, ifreq_len))

@@ -2774,6 +2776,37 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
                ret = 0;
                break;

+       case TUNSETSTEERING:
+               ret = -EFAULT;
+               if (copy_from_user(&steering, argp, sizeof(steering)))
+                       break;
+               ret = 0;
+               switch (steering) {
+               case TUN_STEERING_AUTOMQ:
+                       tun->steering_ops = &tun_automq_ops;
+                       break;
+               default:
+                       ret = -EFAULT;
+               }
+               break;
+
+       case TUNGETSTEERING:
+               ret = 0;
+               if (tun->steering_ops == &tun_automq_ops)
+                       steering = TUN_STEERING_AUTOMQ;
+               else
+                       BUG();
+               if (copy_to_user(argp, &steering, sizeof(steering)))
+                       ret = -EFAULT;
+               break;
+
+       case TUNGETSTEERINGFEATURES:
+               ret = 0;
+               steering = TUN_STEERING_AUTOMQ;
+               if (copy_to_user(argp, &steering, sizeof(steering)))
+                       ret = -EFAULT;
+               break;
+