Le 03/08/2023 à 10:46, Guillaume Nault a écrit :
On Wed, Aug 02, 2023 at 02:21:06PM +0200, Nicolas Dichtel wrote:
This kind of interface doesn't have a mac header.
Well, PPP does have a link layer header.
It has a link layer, but not an ethernet header.
Do you instead mean that PPP automatically adds it?
This patch fixes bpf_redirect() to a ppp interface.
Can you give more details? Which kind of packets are you trying to redirect to PPP interfaces?
My ebpf program redirect an IP packet (eth / ip) from a physical ethernet device at ingress to a ppp device at egress. In this case, the bpf_redirect() function should remove the ethernet header from the packet before calling the xmit ppp function. Before my patch, the ppp xmit function adds a ppp header (protocol IP / 0x0021) before the ethernet header. It results to a corrupted packet. After the patch, the ppp xmit function encapsulates the IP packet, as expected.
To me this looks like a hack to work around the fact that ppp_start_xmit() automatically adds a PPP header. Maybe that's the
It's not an hack, it works like for other kind of devices managed by the function bpf_redirect() / dev_is_mac_header_xmit().
Hope it's more clear.
Regards, Nicolas
best we can do given the current state of ppp_generic.c, but the commit message should be clear about what the real problem is and why the patch takes this approach to fix or work around it.
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
v1 -> v2:
- I forgot the 'Tested-by' tag in the v1 :/
include/linux/if_arp.h | 1 + 1 file changed, 1 insertion(+)
diff --git a/include/linux/if_arp.h b/include/linux/if_arp.h index 1ed52441972f..8efbe29a6f0c 100644 --- a/include/linux/if_arp.h +++ b/include/linux/if_arp.h @@ -53,6 +53,7 @@ static inline bool dev_is_mac_header_xmit(const struct net_device *dev) case ARPHRD_NONE: case ARPHRD_RAWIP: case ARPHRD_PIMREG:
- case ARPHRD_PPP: return false; default: return true;
-- 2.39.2