static bool test_6to4(l4_protocol l4_proto,
int (*create_skb6_fn)(struct tuple *, struct sk_buff **, u16, u8),
int (*create_skb4_fn)(struct tuple *, struct sk_buff **, u16, u8),
u16 expected_payload4_len)
{
struct sk_buff *skb6 = NULL, *skb4_expected = NULL, *skb4_actual = NULL;
struct tuple tuple6, tuple4;
bool result = false;
if (init_ipv6_tuple(&tuple6, "1::1", 50080, "64::192.0.2.5", 51234, L4PROTO_UDP) != 0
|| init_ipv4_tuple(&tuple4, "192.0.2.2", 80, "192.0.2.5", 1234, L4PROTO_UDP) != 0
|| create_skb6_fn(&tuple6, &skb6, 100, 32) != 0
|| create_skb4_fn(&tuple4, &skb4_expected, expected_payload4_len, 31) != 0)
goto end;
if (translating_the_packet(&tuple4, skb6, &skb4_actual) != VER_CONTINUE)
goto end;
result = compare_skbs(skb4_expected, skb4_actual);
/* Fall through. */
end:
kfree_skb(skb6);
kfree_skb(skb4_expected);
kfree_skb(skb4_actual);
return result;
}
/**
* Mirrors the core's behavior by processing skb_in as if it was the incoming packet.
*
* @param skb_in the outgoing packet. Except because it's a hairpin, here it's treated as if it was
* the one received from the network.
* @param tuple_in skb_in's tuple.
* @return whether we managed to U-turn the packet successfully.
*/
verdict handling_hairpinning(struct sk_buff *skb_in, struct tuple *tuple_in)
{
struct sk_buff *skb_out;
struct tuple tuple_out;
verdict result;
log_debug("Step 5: Handling Hairpinning...");
if (skb_l4_proto(skb_in) == L4PROTO_ICMP) {
/* RFC 6146 section 2 (Definition of "Hairpinning"). */
log_debug("ICMP is not supported by hairpinning. Dropping packet...");
return VER_DROP;
}
result = filtering_and_updating(skb_in, tuple_in);
if (result != VER_CONTINUE)
return result;
result = compute_out_tuple(tuple_in, &tuple_out, skb_in);
if (result != VER_CONTINUE)
return result;
result = translating_the_packet(&tuple_out, skb_in, &skb_out);
if (result != VER_CONTINUE)
return result;
result = sendpkt_send(skb_in, skb_out);
if (result != VER_CONTINUE)
return result;
log_debug("Done step 5.");
return VER_CONTINUE;
}
static unsigned int core_common(struct packet *in)
{
struct packet out;
struct tuple tuple_in;
struct tuple tuple_out;
verdict result;
result = determine_in_tuple(in, &tuple_in);
if (result != VERDICT_CONTINUE)
goto end;
result = filtering_and_updating(in, &tuple_in);
if (result != VERDICT_CONTINUE)
goto end;
result = compute_out_tuple(&tuple_in, &tuple_out, in);
if (result != VERDICT_CONTINUE)
goto end;
result = translating_the_packet(&tuple_out, in, &out);
if (result != VERDICT_CONTINUE)
goto end;
if (is_hairpin(&out)) {
result = handling_hairpinning(&out, &tuple_out);
kfree_skb(out.skb);
} else {
result = sendpkt_send(in, &out);
/* send_pkt releases skb_out regardless of verdict. */
}
if (result != VERDICT_CONTINUE)
goto end;
log_debug("Success.");
/*
* The new packet was sent, so the original one can die; drop it.
*
* NF_DROP translates into an error (see nf_hook_slow()).
* Sending a replacing & translated version of the packet should not count as an error,
* so we free the incoming packet ourselves and return NF_STOLEN on success.
*/
kfree_skb(in->skb);
result = VERDICT_STOLEN;
/* Fall through. */
end:
if (result == VERDICT_ACCEPT)
log_debug("Returning the packet to the kernel.");
return (unsigned int) result;
}
/**
* Mirrors the core's behavior by processing skb_in as if it was the incoming packet.
*
* @param skb_in the outgoing packet. Except because it's a hairpin, here it's treated as if it was
* the one received from the network.
* @param tuple_in skb_in's tuple.
* @return whether we managed to U-turn the packet successfully.
*/
verdict handling_hairpinning(struct packet *in, struct tuple *tuple_in)
{
struct packet out;
struct tuple tuple_out;
verdict result;
log_debug("Step 5: Handling Hairpinning...");
if (pkt_l4_proto(in) == L4PROTO_ICMP) {
/*
* RFC 6146 section 2 (Definition of "Hairpinning").
*
* Update 2014-11-21:
* Actually, since ICMP errors count as UDP or TCP packets tuple-wise, maybe the RFC means
* we should only filter out ICMP echoes.
* Or maybe not even that, since they're going to be dropped later anyway, once Jool fails
* to find the mapping.
* Unfortunately, if I remove this if, Jool crashes when I hairpin a ICMP error.
*/
log_debug("ICMP is not supported by hairpinning. Dropping packet...");
return VERDICT_DROP;
}
result = filtering_and_updating(in, tuple_in);
if (result != VERDICT_CONTINUE)
return result;
result = compute_out_tuple(tuple_in, &tuple_out, in);
if (result != VERDICT_CONTINUE)
return result;
result = translating_the_packet(&tuple_out, in, &out);
if (result != VERDICT_CONTINUE)
return result;
result = sendpkt_send(in, &out);
if (result != VERDICT_CONTINUE)
return result;
log_debug("Done step 5.");
return VERDICT_CONTINUE;
}
static unsigned int core_common(struct packet *in)
{
struct packet out;
verdict result;
result = translating_the_packet(NULL, in, &out);
if (result != VERDICT_CONTINUE)
goto end;
result = sendpkt_send(in, &out);
if (result != VERDICT_CONTINUE)
goto end;
log_debug("Success.");
/* See the large comment above. */
kfree_skb(in->skb);
result = VERDICT_STOLEN;
/* Fall through. */
end:
if (result == VERDICT_ACCEPT)
log_debug("Returning the packet to the kernel.");
return (unsigned int) result;
}