{pktgen, xfrm} Construct skb dst for tunnel mode transformation

IPsec tunnel mode encapuslation needs to set outter ip header
with right protocol/ttl/id value with regard to skb->dst->child.

Looking up a rt in a standard way is absolutely wrong for every
packet transmission. In a simple way, construct a dst by setting
neccessary information to make tunnel mode encapuslation working.

Signed-off-by: Fan Du <fan.du@windriver.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 27 insertions, 1 deletions

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 8bc4ddd375a9..628f7c572c6e 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -390,6 +390,8 @@ struct pktgen_dev {
         __u8    ipsmode;                /* IPSEC mode (config) */
         __u8    ipsproto;               /* IPSEC type (config) */
         __u32   spi;
+        struct dst_entry dst;
+        struct dst_ops dstops;
 #endif
         char result[512];
 };
@@ -2487,6 +2489,11 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 
 
 #ifdef CONFIG_XFRM
+u32 pktgen_dst_metrics[RTAX_MAX + 1] = {
+
+        [RTAX_HOPLIMIT] = 0x5, /* Set a static hoplimit */
+};
+
 static int pktgen_output_ipsec(struct sk_buff *skb, struct pktgen_dev *pkt_dev)
 {
         struct xfrm_state *x = pkt_dev->flows[pkt_dev->curfl].x;
@@ -2497,10 +2504,18 @@ static int pktgen_output_ipsec(struct sk_buff *skb, struct pktgen_dev *pkt_dev)
                 return 0;
         /* XXX: we dont support tunnel mode for now until
          * we resolve the dst issue */
-        if (x->props.mode != XFRM_MODE_TRANSPORT)
+        if ((x->props.mode != XFRM_MODE_TRANSPORT) && (pkt_dev->spi == 0))
                 return 0;
 
+        /* But when user specify an valid SPI, transformation
+         * supports both transport/tunnel mode + ESP/AH type.
+         */
+        if ((x->props.mode == XFRM_MODE_TUNNEL) && (pkt_dev->spi != 0))
+                skb->_skb_refdst = (unsigned long)&pkt_dev->dst | SKB_DST_NOREF;
+
+        rcu_read_lock_bh();
         err = x->outer_mode->output(x, skb);
+        rcu_read_unlock_bh();
         if (err) {
                 XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATEMODEERROR);
                 goto error;
@@ -3557,6 +3572,17 @@ static int pktgen_add_device(struct pktgen_thread *t, const char *ifname)
 #ifdef CONFIG_XFRM
         pkt_dev->ipsmode = XFRM_MODE_TRANSPORT;
         pkt_dev->ipsproto = IPPROTO_ESP;
+
+        /* xfrm tunnel mode needs additional dst to extract outter
+         * ip header protocol/ttl/id field, here creat a phony one.
+         * instead of looking for a valid rt, which definitely hurting
+         * performance under such circumstance.
+         */
+        pkt_dev->dstops.family = AF_INET;
+        pkt_dev->dst.dev = pkt_dev->odev;
+        dst_init_metrics(&pkt_dev->dst, pktgen_dst_metrics, false);
+        pkt_dev->dst.child = &pkt_dev->dst;
+        pkt_dev->dst.ops = &pkt_dev->dstops;
 #endif
 
         return add_dev_to_thread(t, pkt_dev);