[PATCH 5.10 298/406] net: handle ARPHRD_PPP in dev_is_mac_header_xmit()

Greg Kroah-Hartman
2023-09-17T19:37:31Z

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

commit a4f39c9f14a634e4cd35fcd338c239d11fcc73fc upstream.

The goal is to support a bpf_redirect() from an ethernet device (ingress)
to a ppp device (egress).
The l2 header is added automatically by the ppp driver, thus the ethernet
header should be removed.

CC: stable@vger.kernel.org
Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Tested-by: Siwar Zitouni <siwar.zitouni@6wind.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/if_arp.h | 4 ++++
1 file changed, 4 insertions(+)

--- a/include/linux/if_arp.h
+++ b/include/linux/if_arp.h
@@ -52,6 +52,10 @@ static inline bool dev_is_mac_header_xmi
case ARPHRD_NONE:
case ARPHRD_RAWIP:
case ARPHRD_PIMREG:
+ /* PPP adds its l2 header automatically in ppp_start_xmit().
+ * This makes it look like an l3 device to __bpf_redirect() and tcf_mirred_init().
+ */
+ case ARPHRD_PPP:
return false;
default:
return true;