The tun driver passes up skb->protocol to userspace in the form of PI headers.
For AF_PACKET injection, we need to support its call chain of:
packet_sendmsg -> packet_snd -> packet_parse_headers ->
dev_parse_header_protocol -> parse_protocol
Without a valid parse_protocol, this returns zero, and the tun driver
then gives userspace bogus values that it can't deal with.
Note that this isn't the case with tap, because tap already benefits
from the shared infrastructure for ethernet headers. But with tun,
there's nothing.
Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com>
---
drivers/net/tun.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 858b012074bd..7adeb91bd368 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -62,6 +62,7 @@
#include <net/rtnetlink.h>
#include <net/sock.h>
#include <net/xdp.h>
+#include <net/ip_tunnels.h>
#include <linux/seq_file.h>
#include <linux/uio.h>
#include <linux/skb_array.h>
@@ -1351,6 +1352,7 @@ static void tun_net_init(struct net_device *dev)
switch (tun->flags & TUN_TYPE_MASK) {
case IFF_TUN:
dev->netdev_ops = &tun_netdev_ops;
+ dev->header_ops = &ip_tunnel_header_ops;
/* Point-to-Point TUN Device */
dev->hard_header_len = 0;
--
2.27.0
