static unsigned int fw_confirm(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
confirm_connection(*pskb);
return NF_ACCEPT;
}
/* Handle received packets for not yet established crypto connections. */
static void receive_crypto(Net_Crypto *c)
{
uint32_t i;
uint64_t temp_time = unix_time();
for (i = 0; i < c->crypto_connections_length; ++i) {
if (c->crypto_connections[i].status == CRYPTO_CONN_NO_CONNECTION)
continue;
if (c->crypto_connections[i].status == CRYPTO_CONN_HANDSHAKE_SENT) {
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t secret_nonce[crypto_box_NONCEBYTES];
uint8_t public_key[crypto_box_PUBLICKEYBYTES];
uint8_t session_key[crypto_box_PUBLICKEYBYTES];
uint16_t len;
if (id_packet(c->lossless_udp, c->crypto_connections[i].number) == 2) { /* Handle handshake packet. */
len = read_packet(c->lossless_udp, c->crypto_connections[i].number, temp_data);
if (handle_cryptohandshake(c, public_key, secret_nonce, session_key, temp_data, len)) {
if (memcmp(public_key, c->crypto_connections[i].public_key, crypto_box_PUBLICKEYBYTES) == 0) {
memcpy(c->crypto_connections[i].sent_nonce, secret_nonce, crypto_box_NONCEBYTES);
memcpy(c->crypto_connections[i].peersessionpublic_key, session_key, crypto_box_PUBLICKEYBYTES);
increment_nonce(c->crypto_connections[i].sent_nonce);
uint32_t zero = 0;
encrypt_precompute(c->crypto_connections[i].peersessionpublic_key,
c->crypto_connections[i].sessionsecret_key,
c->crypto_connections[i].shared_key);
c->crypto_connections[i].status =
CRYPTO_CONN_ESTABLISHED; /* Connection status needs to be 3 for write_cryptpacket() to work. */
write_cryptpacket(c, i, ((uint8_t *)&zero), sizeof(zero));
c->crypto_connections[i].status = CRYPTO_CONN_NOT_CONFIRMED; /* Set it to its proper value right after. */
} else {
/* This should not happen, timeout the connection if it does. */
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
} else {
/* This should not happen, timeout the connection if it does. */
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
} else if (id_packet(c->lossless_udp,
c->crypto_connections[i].number) != -1) {
/* This should not happen, timeout the connection if it does. */
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
}
if (c->crypto_connections[i].status == CRYPTO_CONN_NOT_CONFIRMED) {
if (id_packet(c->lossless_udp, c->crypto_connections[i].number) == 3) {
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t data[MAX_DATA_SIZE];
int length = read_packet(c->lossless_udp, c->crypto_connections[i].number, temp_data);
int len = decrypt_data(c->crypto_connections[i].peersessionpublic_key,
c->crypto_connections[i].sessionsecret_key,
c->crypto_connections[i].recv_nonce, temp_data + 1, length - 1, data);
uint32_t zero = 0;
if (len == sizeof(uint32_t) && memcmp(((uint8_t *)&zero), data, sizeof(uint32_t)) == 0) {
increment_nonce(c->crypto_connections[i].recv_nonce);
encrypt_precompute(c->crypto_connections[i].peersessionpublic_key,
c->crypto_connections[i].sessionsecret_key,
c->crypto_connections[i].shared_key);
c->crypto_connections[i].status = CRYPTO_CONN_ESTABLISHED;
c->crypto_connections[i].timeout = ~0;
/* Connection is accepted. */
confirm_connection(c->lossless_udp, c->crypto_connections[i].number);
} else {
/* This should not happen, timeout the connection if it does. */
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
} else if (id_packet(c->lossless_udp, c->crypto_connections[i].number) != -1) {
/* This should not happen, timeout the connection if it does. */
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
}
if (temp_time > c->crypto_connections[i].timeout) {
c->crypto_connections[i].status = CRYPTO_CONN_TIMED_OUT;
}
}
}
static unsigned int
fw_in(unsigned int hooknum,
struct sk_buff **pskb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
int ret = FW_BLOCK;
u_int16_t redirpt;
/* Assume worse case: any hook could change packet */
(*pskb)->nfcache |= NFC_UNKNOWN | NFC_ALTERED;
(*pskb)->ip_summed = CHECKSUM_NONE;
switch (hooknum) {
case NF_IP_PRE_ROUTING:
if (fwops->fw_acct_in)
fwops->fw_acct_in(fwops, PF_INET,
(struct net_device *)in,
(*pskb)->nh.raw, &redirpt, pskb);
if ((*pskb)->nh.iph->frag_off & htons(IP_MF|IP_OFFSET)) {
*pskb = ip_ct_gather_frags(*pskb);
if (!*pskb)
return NF_STOLEN;
}
ret = fwops->fw_input(fwops, PF_INET, (struct net_device *)in,
(*pskb)->nh.raw, &redirpt, pskb);
break;
case NF_IP_FORWARD:
/* Connection will only be set if it was
demasqueraded: if so, skip forward chain. */
if ((*pskb)->nfct)
ret = FW_ACCEPT;
else ret = fwops->fw_forward(fwops, PF_INET,
(struct net_device *)out,
(*pskb)->nh.raw, &redirpt, pskb);
break;
case NF_IP_POST_ROUTING:
ret = fwops->fw_output(fwops, PF_INET,
(struct net_device *)out,
(*pskb)->nh.raw, &redirpt, pskb);
if (ret == FW_ACCEPT || ret == FW_SKIP) {
if (fwops->fw_acct_out)
fwops->fw_acct_out(fwops, PF_INET,
(struct net_device *)in,
(*pskb)->nh.raw, &redirpt,
pskb);
confirm_connection(*pskb);
}
break;
}
switch (ret) {
case FW_REJECT: {
/* Alexey says:
*
* Generally, routing is THE FIRST thing to make, when
* packet enters IP stack. Before packet is routed you
* cannot call any service routines from IP stack. */
struct iphdr *iph = (*pskb)->nh.iph;
if ((*pskb)->dst != NULL
|| ip_route_input(*pskb, iph->daddr, iph->saddr, iph->tos,
(struct net_device *)in) == 0)
icmp_send(*pskb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH,
0);
return NF_DROP;
}
case FW_ACCEPT:
case FW_SKIP:
if (hooknum == NF_IP_PRE_ROUTING) {
check_for_demasq(pskb);
check_for_redirect(*pskb);
} else if (hooknum == NF_IP_POST_ROUTING) {
check_for_unredirect(*pskb);
/* Handle ICMP errors from client here */
if ((*pskb)->nh.iph->protocol == IPPROTO_ICMP
&& (*pskb)->nfct)
check_for_masq_error(*pskb);
}
return NF_ACCEPT;
case FW_MASQUERADE:
if (hooknum == NF_IP_FORWARD)
return do_masquerade(pskb, out);
else return NF_ACCEPT;
case FW_REDIRECT:
if (hooknum == NF_IP_PRE_ROUTING)
return do_redirect(*pskb, in, redirpt);
else return NF_ACCEPT;
default:
/* FW_BLOCK */
return NF_DROP;
}
}