[PATCH net-next v3 4/4 RFC] pktgen: Allow sending IPv4 TCP packets

From: Zoltan Kiss
Date: Wed Jul 30 2014 - 12:21:18 EST


This is a prototype patch to enable sending IPv4 TCP packets with pktgen. The
original motivation is to test TCP GSO with xen-netback/netfront, but I'm not
sure about how the checksum should be set up, and also someone should verify the
GSO settings I'm using.

Signed-off-by: Zoltan Kiss <zoltan.kiss@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Thomas Graf <tgraf@xxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
---
v3:
- mention explicitly that this for IPv4
- memset the TCP header and set up doff
- rework of checksum handling and GSO setting in fill_packet_ipv4
- bail out in pktgen_xmit if the device won't be able to handle GSO

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 0d0aaac..9d93bda 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -162,6 +162,7 @@
#include <net/checksum.h>
#include <net/ipv6.h>
#include <net/udp.h>
+#include <net/tcp.h>
#include <net/ip6_checksum.h>
#include <net/addrconf.h>
#ifdef CONFIG_XFRM
@@ -203,6 +204,7 @@
#define F_NODE (1<<15) /* Node memory alloc*/
#define F_UDPCSUM (1<<16) /* Include UDP checksum */
#define F_PATTERN (1<<17) /* Fill the payload with a pattern */
+#define F_TCP (1<<18) /* Send TCP packet instead of UDP */

/* Thread control flag bits */
#define T_STOP (1<<0) /* Stop run */
@@ -664,6 +666,9 @@ static int pktgen_if_show(struct seq_file *seq, void *v)
if (pkt_dev->flags & F_PATTERN)
seq_puts(seq, "PATTERN ");

+ if (pkt_dev->flags & F_TCP)
+ seq_puts(seq, "TCP ");
+
if (pkt_dev->flags & F_MPLS_RND)
seq_puts(seq, "MPLS_RND ");

@@ -1342,6 +1347,12 @@ static ssize_t pktgen_if_write(struct file *file,
else if (strcmp(f, "!PATTERN") == 0)
pkt_dev->flags &= ~F_PATTERN;

+ else if (strcmp(f, "TCP") == 0)
+ pkt_dev->flags |= F_TCP;
+
+ else if (strcmp(f, "!TCP") == 0)
+ pkt_dev->flags &= ~F_TCP;
+
else {
sprintf(pg_result,
"Flag -:%s:- unknown\nAvailable flags, (prepend ! to un-set flag):\n%s",
@@ -2955,7 +2966,8 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
{
struct sk_buff *skb = NULL;
__u8 *eth;
- struct udphdr *udph;
+ struct udphdr *udph = NULL;
+ struct tcphdr *tcph;
int datalen, iplen;
struct iphdr *iph;
__be16 protocol = htons(ETH_P_IP);
@@ -3017,29 +3029,40 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
iph = (struct iphdr *) skb_put(skb, sizeof(struct iphdr));

skb_set_transport_header(skb, skb->len);
- udph = (struct udphdr *) skb_put(skb, sizeof(struct udphdr));
+
+ if (pkt_dev->flags & F_TCP) {
+ datalen = pkt_dev->cur_pkt_size - ETH_HLEN - 20 -
+ sizeof(struct tcphdr) - pkt_dev->pkt_overhead;
+ tcph = (struct tcphdr *)skb_put(skb, sizeof(struct tcphdr));
+ memset(tcph, 0, sizeof(*tcph));
+ tcph->source = htons(pkt_dev->cur_udp_src);
+ tcph->dest = htons(pkt_dev->cur_udp_dst);
+ tcph->doff = sizeof(struct tcphdr) >> 2;
+ } else {
+ datalen = pkt_dev->cur_pkt_size - ETH_HLEN - 20 -
+ sizeof(struct udphdr) - pkt_dev->pkt_overhead;
+ udph = (struct udphdr *)skb_put(skb, sizeof(struct udphdr));
+ udph->source = htons(pkt_dev->cur_udp_src);
+ udph->dest = htons(pkt_dev->cur_udp_dst);
+ udph->len = htons(datalen + sizeof(struct udphdr));
+ udph->check = 0;
+ }
+
skb_set_queue_mapping(skb, queue_map);
skb->priority = pkt_dev->skb_priority;

memcpy(eth, pkt_dev->hh, 12);
*(__be16 *) & eth[12] = protocol;

- /* Eth + IPh + UDPh + mpls */
- datalen = pkt_dev->cur_pkt_size - 14 - 20 - 8 -
- pkt_dev->pkt_overhead;
if (datalen < 0 || datalen < sizeof(struct pktgen_hdr))
datalen = sizeof(struct pktgen_hdr);

- udph->source = htons(pkt_dev->cur_udp_src);
- udph->dest = htons(pkt_dev->cur_udp_dst);
- udph->len = htons(datalen + 8); /* DATA + udphdr */
- udph->check = 0;

iph->ihl = 5;
iph->version = 4;
iph->ttl = 32;
iph->tos = pkt_dev->tos;
- iph->protocol = IPPROTO_UDP; /* UDP */
+ iph->protocol = pkt_dev->flags & F_TCP ? IPPROTO_TCP : IPPROTO_UDP;
iph->saddr = pkt_dev->cur_saddr;
iph->daddr = pkt_dev->cur_daddr;
iph->id = htons(pkt_dev->ip_id);
@@ -3055,9 +3078,14 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,
if (!(pkt_dev->flags & F_UDPCSUM)) {
skb->ip_summed = CHECKSUM_NONE;
} else if (odev->features & NETIF_F_V4_CSUM) {
- skb->ip_summed = CHECKSUM_PARTIAL;
- skb->csum = 0;
- udp4_hwcsum(skb, udph->source, udph->dest);
+ skb_checksum_setup(skb, true);
+ } else if (pkt_dev->flags & F_TCP) {
+ struct inet_sock inet;
+
+ inet.inet_saddr = iph->saddr;
+ inet.inet_daddr = iph->daddr;
+ skb->ip_summed = CHECKSUM_NONE;
+ tcp_v4_send_check((struct sock *)&inet, skb);
} else {
__wsum csum = udp_csum(skb);

@@ -3072,6 +3100,20 @@ static struct sk_buff *fill_packet_ipv4(struct net_device *odev,

pktgen_finalize_skb(pkt_dev, skb, datalen);

+ if (odev->mtu < skb->len) {
+ int hdrlen = skb_transport_header(skb) - skb_mac_header(skb);
+
+ if (pkt_dev->flags & F_TCP) {
+ skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
+ hdrlen += tcp_hdrlen(skb);
+ } else {
+ skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
+ hdrlen += sizeof(struct udphdr);
+ }
+ skb_shinfo(skb)->gso_size = odev->mtu - hdrlen;
+ skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len - hdrlen, skb_shinfo(skb)->gso_size);
+ }
+
#ifdef CONFIG_XFRM
if (!process_ipsec(pkt_dev, skb, protocol))
return NULL;
@@ -3559,6 +3601,14 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->last_pkt_size = pkt_dev->skb->len;
pkt_dev->allocated_skbs++;
pkt_dev->clone_count = 0; /* reset counter */
+
+ if (netif_needs_gso(pkt_dev->skb, netif_skb_features(pkt_dev->skb))) {
+ pr_err("Device don't have necessary GSO features! netif_skb_features: %llX summed %u\n",
+ netif_skb_features(pkt_dev->skb),
+ pkt_dev->skb->ip_summed);
+ pkt_dev->sofar++;
+ goto out;
+ }
}

if (pkt_dev->delay && pkt_dev->last_ok)
@@ -3608,7 +3658,7 @@ unlock:
HARD_TX_UNLOCK(odev, txq);

local_bh_enable();
-
+out:
/* If pkt_dev->count is zero, then run forever */
if ((pkt_dev->count != 0) && (pkt_dev->sofar >= pkt_dev->count)) {
pktgen_wait_for_skb(pkt_dev);
--
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