netdev - Re: [PATCH 0/9][RFC] KVM virtio

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 11 Aug 2008 17:44:27 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Anthony Liguori <anthony@...emonkey.ws>
Cc:	netdev@...r.kernel.org, David Miller <davem@...emloft.net>
Subject: Re: [PATCH 0/9][RFC] KVM virtio_net performance

On Friday 25 July 2008 06:56:01 you wrote:
> I'm still seeing the same problem I saw with my patch series.  Namely,
> dhclient fails to get a DHCP address.

This is, from one point of view, a dhclient bug.  It opens a packet socket, 
and we'd tell it that the checksum is incomplete via auxdata, but it doesn't 
have auxdata.

On the other hand, perhaps we should copy the packet and checksum it in this 
case?  Not many devices input packets with partial csums, so dhclient doesn't 
normally hit this.  Xen might though?

ie, in net/packet/af_packet.c's packet_recvmsg():

	if (pkt_sk(sk)->auxdata) {
		struct tpacket_auxdata aux;

		aux.tp_status = TP_STATUS_USER;
		if (skb->ip_summed == CHECKSUM_PARTIAL)
			aux.tp_status |= TP_STATUS_CSUMNOTREADY;
		aux.tp_len = PACKET_SKB_CB(skb)->origlen;
		aux.tp_snaplen = skb->len;
		aux.tp_mac = 0;
		aux.tp_net = skb_network_offset(skb);
		aux.tp_vlan_tci = skb->vlan_tci;

		put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
	}

add an "else if (skb->ip_summed == CHECKSUM_PARTIAL)" case...

Rusty.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html