IPSec Inbound Processing Basic Doubt

From: k8 s
Date: Thu Jun 23 2005 - 12:58:47 EST


I have a basic doubt regarding ipsec inbound packet processing.
I have idea about the stackable destination.If I am not wrong it is like this.
/* Output packet to network from transport. */
static inline int dst_output(struct sk_buff *skb)
int err;

for (;;) {
err = skb->dst->output(skb);

if (likely(err == 0))
return err;
if (unlikely(err != NET_XMIT_BYPASS))
return err;

here skb->dst->oututput(skb)
skb->dst = dst_pop(skb);

And x->type->output(skb) calls ah_output | esp_output and the skb->dst
value is reset during dst_pop(skb)

All methods return non zero for the dst_output for loop to continue
except ip_queue_xmit (I Think) which returns 0 and the for loop
exits. Error reporting by any member in the chain is through returning
XMIT_BYPASS or similar

I hope Its the way

My doubt regarding Inbound processing is
err = skb->dst->input()
hope that it calls rxfrm4_rcv (ipv4) calls

//also there is a
netif_rx(skb) in the same method
and x->type->input() calling ah_input | esp_input()

Now is it that
a) inbound is similar to outbound stackable destination calls except
that the calls are in
reverse direction
b)Does netif_rx call in xfrm4_rcv_encap mean one of the many xfrms of
ipsec gets processed first and the packet is fed back to the ipstack
through netif_rx() and the whole game starts again with ip_rcv
checking protocol finding 50 0r 51 and calling xfrm4_rcv

So is it a call chain
packet looping between ipsec and ip continuosly using netif_rx and
ip_rcv and xfrm4_rcv

S Kartikeyan
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