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Date: Mon, 31 Aug 2015 10:02:14 -0700
From: Tom Herbert <tom@...bertland.com>
To: David Ahern <dsa@...ulusnetworks.com>
Cc: Linux Kernel Network Developers <netdev@...r.kernel.org>,
Shrijeet Mukherjee <shm@...ulusnetworks.com>
Subject: Re: [PATCH net-next] net: Remove VRF change to udp_sendmsg
On Mon, Aug 31, 2015 at 9:29 AM, David Ahern <dsa@...ulusnetworks.com> wrote:
> Remove the VRF change in udp_sendmsg to set the source address. The VRF
> driver already has access to the packet on the TX path via the dst. It
> can be used to update the source address in the header.
>
I don't understand this. The previous code was about selecting a
source address for packets being sourced ed on a socket, but this new
patch seems to essentially be doing SNAT in the VRF transmit path
which seems like a fundamentally different behavior. Is this really
your intention?
Thanks,
Tom
>
> Cc: Tom Herbert <tom@...bertland.com>
> Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
> ---
> drivers/net/vrf.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
> net/ipv4/udp.c | 18 ----------------
> 2 files changed, 58 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
> index e7094fbd7568..169418254636 100644
> --- a/drivers/net/vrf.c
> +++ b/drivers/net/vrf.c
> @@ -160,6 +160,58 @@ static netdev_tx_t vrf_process_v6_outbound(struct sk_buff *skb,
> return NET_XMIT_DROP;
> }
>
> +static void update_ipv4_saddr(struct sk_buff *skb, struct iphdr *iph,
> + __be32 new_addr)
> +{
> + int tlen = skb->len - skb_transport_offset(skb);
> +
> + if (iph->protocol == IPPROTO_TCP) {
> + if (likely(tlen >= sizeof(struct tcphdr))) {
> + inet_proto_csum_replace4(&tcp_hdr(skb)->check, skb,
> + iph->saddr, new_addr, 1);
> + }
> + } else if (iph->protocol == IPPROTO_UDP) {
> + if (likely(tlen >= sizeof(struct udphdr))) {
> + struct udphdr *uh = udp_hdr(skb);
> +
> + if (uh->check || skb->ip_summed == CHECKSUM_PARTIAL) {
> + inet_proto_csum_replace4(&uh->check, skb,
> + iph->saddr, new_addr,
> + 1);
> + if (!uh->check)
> + uh->check = CSUM_MANGLED_0;
> + }
> + }
> + }
> +
> + csum_replace4(&iph->check, iph->saddr, new_addr);
> + skb_clear_hash(skb);
> + iph->saddr = new_addr;
> +}
> +
> +static int vrf_set_ip_saddr(struct sk_buff *skb, struct net_device *dev)
> +{
> + struct iphdr *ip4h = ip_hdr(skb);
> + struct flowi4 fl4 = {
> + .flowi4_oif = dev->ifindex,
> + .flowi4_iif = LOOPBACK_IFINDEX,
> + .flowi4_tos = RT_TOS(ip4h->tos),
> + .flowi4_flags = FLOWI_FLAG_ANYSRC | FLOWI_FLAG_VRFSRC,
> + .daddr = ip4h->daddr,
> + };
> + struct rtable *rt;
> +
> + rt = __ip_route_output_key(dev_net(dev), &fl4);
> + if (IS_ERR(rt))
> + return 1;
> +
> + ip_rt_put(rt);
> +
> + update_ipv4_saddr(skb, ip4h, fl4.saddr);
> +
> + return 0;
> +}
> +
> static int vrf_send_v4_prep(struct sk_buff *skb, struct flowi4 *fl4,
> struct net_device *vrf_dev)
> {
> @@ -200,11 +252,6 @@ static netdev_tx_t vrf_process_v4_outbound(struct sk_buff *skb,
> if (vrf_send_v4_prep(skb, &fl4, vrf_dev))
> goto err;
>
> - if (!ip4h->saddr) {
> - ip4h->saddr = inet_select_addr(skb_dst(skb)->dev, 0,
> - RT_SCOPE_LINK);
> - }
> -
> ret = ip_local_out(skb);
> if (unlikely(net_xmit_eval(ret)))
> vrf_dev->stats.tx_errors++;
> @@ -298,12 +345,18 @@ static int vrf_finish_output(struct sock *sk, struct sk_buff *skb)
> static int vrf_output(struct sock *sk, struct sk_buff *skb)
> {
> struct net_device *dev = skb_dst(skb)->dev;
> + struct iphdr *iph = ip_hdr(skb);
>
> IP_UPD_PO_STATS(dev_net(dev), IPSTATS_MIB_OUT, skb->len);
>
> skb->dev = dev;
> skb->protocol = htons(ETH_P_IP);
>
> + if (!iph->saddr && vrf_set_ip_saddr(skb, dev)) {
> + vrf_tx_error(dev, skb);
> + return -EINVAL;
> + }
> +
> return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, sk, skb,
> NULL, dev,
> vrf_finish_output,
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index c0a15e7f359f..ee3ba30f1ca5 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1017,24 +1017,6 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>
> fl4 = &fl4_stack;
>
> - /* unconnected socket. If output device is enslaved to a VRF
> - * device lookup source address from VRF table. This mimics
> - * behavior of ip_route_connect{_init}.
> - */
> - if (netif_index_is_vrf(net, ipc.oif)) {
> - flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
> - RT_SCOPE_UNIVERSE, sk->sk_protocol,
> - (flow_flags | FLOWI_FLAG_VRFSRC),
> - faddr, saddr, dport,
> - inet->inet_sport);
> -
> - rt = ip_route_output_flow(net, fl4, sk);
> - if (!IS_ERR(rt)) {
> - saddr = fl4->saddr;
> - ip_rt_put(rt);
> - }
> - }
> -
> flowi4_init_output(fl4, ipc.oif, sk->sk_mark, tos,
> RT_SCOPE_UNIVERSE, sk->sk_protocol,
> flow_flags,
> --
> 1.9.1
>
--
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