tun: TUNSETFEATURES to set gso features.

ethtool is useful for setting (some) device fields, but it's
root-only.  Finer feature control is available through a tun-specific
ioctl.

(Includes Mark McLoughlin <markmc@redhat.com>'s fix to hold rtnl sem).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/if_tun.h b/include/linux/if_tun.h
index 94f76a112303..3f0a0995d449 100644
--- a/include/linux/if_tun.h
+++ b/include/linux/if_tun.h
@@ -41,6 +41,7 @@
 #define TUNSETLINK    _IOW('T', 205, int)
 #define TUNSETGROUP   _IOW('T', 206, int)
 #define TUNGETFEATURES _IOR('T', 207, unsigned int)
+#define TUNSETOFFLOAD _IOW('T', 208, unsigned int)
 
 /* TUNSETIFF ifr flags */
 #define IFF_TUN         0x0001
@@ -48,6 +49,12 @@
 #define IFF_NO_PI       0x1000
 #define IFF_ONE_QUEUE   0x2000
 
+/* Features for GSO (TUNSETOFFLOAD). */
+#define TUN_F_CSUM      0x01    /* You can hand me unchecksummed packets. */
+#define TUN_F_TSO4      0x02    /* I can handle TSO for IPv4 packets */
+#define TUN_F_TSO6      0x04    /* I can handle TSO for IPv6 packets */
+#define TUN_F_TSO_ECN   0x08    /* I can handle TSO with ECN bits. */
+
 struct tun_pi {
         unsigned short flags;
         __be16 proto;