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mirror of https://code.semirocket.science/wrapsix synced 2024-11-21 13:31:02 +02:00

Base of enhanced ICMP support

Translated ICMPv4 packets are statically allocated
ICMPv4 sanitizes size of payload
Fix of an overflow
This commit is contained in:
Michal Zima 2013-03-27 18:44:08 +01:00
parent f7a03e8240
commit d1a25aee7f
2 changed files with 350 additions and 37 deletions

View File

@ -27,7 +27,9 @@
#include "linkedlist.h"
#include "log.h"
#include "nat.h"
#include "tcp.h"
#include "transmitter.h"
#include "udp.h"
#include "wrapper.h"
/**
@ -46,16 +48,34 @@
int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
char *payload, unsigned short payload_size)
{
struct s_icmp *icmp;
unsigned char *icmp_data;
struct s_nat *connection;
unsigned short orig_checksum;
unsigned char *packet;
struct s_icmp *icmp;
unsigned int *icmp_extra;
unsigned short *icmp_extra_s;
unsigned char *icmp_data;
struct s_nat *connection;
unsigned short orig_checksum;
unsigned char packet[MTU + sizeof(struct s_ethernet)];
struct s_icmp_echo *echo;
struct s_ethernet *eth6;
struct s_ipv6 *ip6;
/* for error messages */
unsigned short payload_size_left, new_len;
struct s_ipv4 *eip4;
struct s_ipv6 *eip6;
struct s_tcp *etcp;
struct s_udp *eudp;
struct s_icmp *eicmp;
unsigned short eip4_hlen;
struct s_ipv6_fragment *eip6_frag;
/* sanity check */
if (payload_size < sizeof(struct s_icmp) + 4) {
log_debug("Too short ICMPv4 packet");
return 1;
}
icmp = (struct s_icmp *) payload;
icmp_data = (unsigned char *) (payload + sizeof(struct s_icmp));
@ -71,11 +91,9 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
}
switch (icmp->type) {
case ICMPV4_ECHO_REQUEST:
/* this is pretty non-sense situation */
return 1;
case ICMPV4_ECHO_REPLY:
/* this option is already sanitized */
echo = (struct s_icmp_echo *) icmp_data;
connection = nat_in(nat4_icmp, ip4->ip_src,
@ -94,23 +112,309 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
/* override information in original ICMP header */
icmp->type = ICMPV6_ECHO_REPLY;
new_len = sizeof(struct s_ethernet) +
sizeof(struct s_ipv6);
/* copy the payload data */
payload_size_left = payload_size >
MTU - sizeof(struct s_ipv6) ?
MTU - sizeof(struct s_ipv6) : payload_size;
memcpy(&packet[new_len], payload, payload_size_left);
icmp = (struct s_icmp *) &packet[new_len];
new_len += payload_size_left;
break;
case ICMPV4_DST_UNREACHABLE:
if (icmp->code <= 13 || icmp->code == 15) {
/* sanity check */
payload_size_left = payload_size -
sizeof(struct s_icmp) - 4;
if (payload_size_left < 1) {
log_debug("Too short ICMPv4 packet 2");
return 1;
}
/* skip unused space */
icmp_data += 4;
/* parse IPv4 header */
eip4 = (struct s_ipv4 *) icmp_data;
/* # of 4 byte words */
eip4_hlen = (eip4->ver_hdrlen & 0x0f) * 4;
/* sanity check */
if (payload_size_left < eip4_hlen + 4) {
log_debug("Too short ICMPv4 packet 3");
return 1;
}
/* 4 B -> L4 addrs */
payload_size_left -= eip4_hlen + 4;
icmp_data += eip4_hlen;
new_len = sizeof(struct s_ethernet) +
sizeof(struct s_ipv6);
/* define new inner IPv6 header */
/* new_len+4+4+40=102 < 1280 */
eip6 = (struct s_ipv6 *) &packet[new_len +
sizeof(struct s_icmp) + 4];
/* we'll need this right now */
ipv4_to_ipv6(&eip4->ip_dest, &eip6->ip_dest);
/* look for the original connection */
switch (eip4->proto) {
case IPPROTO_TCP:
etcp = (struct s_tcp *)
icmp_data;
connection = nat_in(nat4_tcp,
eip4->ip_dest,
etcp->port_dest,
etcp->port_src);
if (connection == NULL) {
log_debug("Incoming "
"TCP error "
"connection "
"wasn't found "
"in NAT");
return 1;
}
/* fix port for local client */
etcp->port_src = connection->
ipv6_port_src;
break;
case IPPROTO_UDP:
eudp = (struct s_udp *)
icmp_data;
connection = nat_in(nat4_udp,
eip4->ip_dest,
eudp->port_dest,
eudp->port_src);
if (connection == NULL) {
log_debug("Incoming "
"UDP error "
"connection "
"wasn't found "
"in NAT");
return 1;
}
/* fix port for local client */
eudp->port_src = connection->
ipv6_port_src;
break;
case IPPROTO_ICMP:
eicmp = (struct s_icmp *)
icmp_data;
/* we translate only echo
* requests so handle only them
* here too */
if (eicmp->type !=
ICMPV4_ECHO_REQUEST) {
log_debug("Unknown ICMP"
" type within "
"ICMP error");
return 1;
}
/* else: */
/* sanity check */
if (payload_size_left < 4) {
log_debug("Too short "
"ICMPv4 packet "
"4");
return 1;
}
echo = (struct s_icmp_echo *)
(icmp_data +
sizeof(struct s_icmp));
connection = nat_in(nat4_icmp,
eip4->ip_dest, 0,
echo->id);
if (connection == NULL) {
log_debug("Incoming "
"ICMP error "
"connection "
"wasn't found "
"in NAT");
return 1;
}
/* fix port for local client */
echo->id = connection->
ipv6_port_src;
/* adjust ICMP type */
eicmp->type =
ICMPV6_ECHO_REQUEST;
break;
default:
/* we don't know where to send
* it */
return 1;
}
/* copy ICMP header to new packet */
memcpy(&packet[new_len], icmp,
sizeof(struct s_icmp) + 4);
icmp = (struct s_icmp *) &packet[new_len];
new_len += sizeof(struct s_icmp) + 4;
/* complete inner IPv6 header */
eip6->ver = 0x60 | (eip4->tos >> 4);
eip6->traffic_class = eip4->tos << 4;
eip6->flow_label = 0x0;
eip6->hop_limit = eip4->ttl;
if (eip4->proto != IPPROTO_ICMP) {
eip6->next_header = eip4->proto;
} else {
eip6->next_header = IPPROTO_ICMPV6;
}
eip6->ip_src = connection->ipv6;
new_len += sizeof(struct s_ipv6);
/* was the IPv4 packet fragmented? */
if ((eip4->flags_offset & htons(0x1fff)) !=
0x0000) {
/* original length of error packet,
* but without IP header, but with
* fragment header(!) */
eip6->len = htons(ntohs(eip4->len) -
eip4_hlen +
sizeof(struct s_ipv6_fragment));
eip6_frag = (struct s_ipv6_fragment *)
&packet[new_len];
eip6_frag->next_header =
eip6->next_header;
eip6->next_header = IPPROTO_FRAGMENT;
eip6_frag->id = htonl(ntohs(eip4->id));
new_len +=
sizeof(struct s_ipv6_fragment);
} else {
eip6->len = htons(ntohs(eip4->len) -
eip4_hlen);
}
/* translate ICMP type&code */
if (icmp->code == 2) {
icmp->type = ICMPV6_PARAM_PROBLEM;
icmp->code = 1;
icmp_extra = (unsigned int *)
(((unsigned char *) icmp) +
sizeof(struct s_icmp));
if (eip6->next_header ==
IPPROTO_FRAGMENT) {
/* field next_header in FragH */
*icmp_extra = htonl(40);
} else {
/* field next_header in IPv6 */
*icmp_extra = htonl(6);
}
} else if (icmp->code == 4) {
icmp->type = ICMPV6_PKT_TOO_BIG;
icmp->code = 0;
icmp_extra = (unsigned int *)
(((unsigned char *) icmp) +
sizeof(struct s_icmp));
icmp_extra_s = (unsigned short *)
(((unsigned char *) icmp) +
sizeof(struct s_icmp) + 2);
if (ntohs(*icmp_extra_s) < 68) {
*icmp_extra = htonl(
*icmp_extra_s + 20 <
MTU ? (unsigned int)
*icmp_extra_s + 20 :
MTU);
} else {
/* RFC1191 */
/* NOTE: >= would cause infinite
* loop */
/* 1492+ don't have to be
* checked -- the biggest packet
* we can send there is 1480 */
if (ntohs(eip4->len) >
1006) {
*icmp_extra =
htonl(1006);
} else if (ntohs(eip4->len) >
508) {
*icmp_extra =
htonl(508);
} else if (ntohs(eip4->len) >
296) {
*icmp_extra =
htonl(296);
} else {
*icmp_extra = htonl(68);
}
}
} else if (icmp->code == 3) {
icmp->type = ICMPV6_DST_UNREACHABLE;
icmp->code = 4;
} else if (icmp->code == 9 ||
icmp->code == 10 ||
icmp->code == 13 ||
icmp->code == 15) {
icmp->type = ICMPV6_DST_UNREACHABLE;
icmp->code = 1;
} else {
icmp->type = ICMPV6_DST_UNREACHABLE;
icmp->code = 0;
}
/* copy payload, aligned to MTU */
/* we can afford to use full MTU instead of
* just 1280 B as admin warrants this to us */
if (payload_size - sizeof(struct s_icmp) - 4 -
eip4_hlen > (unsigned int) MTU - new_len) {
memcpy(&packet[new_len], icmp_data,
MTU - new_len);
new_len = MTU;
} else {
memcpy(&packet[new_len], icmp_data,
payload_size -
sizeof(struct s_icmp) - 4 -
eip4_hlen);
new_len += payload_size -
sizeof(struct s_icmp) - 4 -
eip4_hlen;
}
/* new packet is almost finished, yay! */
break;
} else {
/* silently drop */
return 0;
}
default:
log_debug("ICMPv4 Type: unknown [%d/0x%x]",
icmp->type, icmp->type);
return 1;
/* silently drop */
return 0;
}
/* allocate memory for translated packet */
if ((packet = (unsigned char *) malloc(sizeof(struct s_ethernet) +
sizeof(struct s_ipv6) +
payload_size)) == NULL) {
log_error("Lack of free memory");
return 1;
}
eth6 = (struct s_ethernet *) packet;
ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet));
eth6 = (struct s_ethernet *) &packet[0];
ip6 = (struct s_ipv6 *) &packet[sizeof(struct s_ethernet)];
/* build ethernet header */
eth6->dest = connection->mac;
@ -121,27 +425,21 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
ip6->ver = 0x60 | (ip4->tos >> 4);
ip6->traffic_class = ip4->tos << 4;
ip6->flow_label = 0x0;
ip6->len = htons(payload_size);
ip6->len = htons(new_len - sizeof(struct s_ethernet) - sizeof(struct s_ipv6));
ip6->next_header = IPPROTO_ICMPV6;
ip6->hop_limit = ip4->ttl;
ipv4_to_ipv6(&ip4->ip_src, &ip6->ip_src);
ip6->ip_dest = connection->ipv6;
/* compute ICMP checksum */
/* compute ICMP checksum; this is already in new packet */
icmp->checksum = 0x0;
icmp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, payload_size,
IPPROTO_ICMPV6, (unsigned char *) icmp);
/* copy the payload data (with new checksum) */
memcpy(packet + sizeof(struct s_ethernet) + sizeof(struct s_ipv6),
payload, payload_size);
icmp->checksum = checksum_ipv6(ip6->ip_src, ip6->ip_dest, new_len -
sizeof(struct s_ethernet) -
sizeof(struct s_ipv6), IPPROTO_ICMPV6,
(unsigned char *) icmp);
/* send translated packet */
transmit_raw(packet, sizeof(struct s_ethernet) + sizeof(struct s_ipv6) +
payload_size);
/* clean-up */
free(packet);
transmit_raw(&packet[0], new_len);
return 0;
}
@ -370,6 +668,7 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
unsigned char code, unsigned char *data, unsigned short length)
{
unsigned char *packet, *payload;
unsigned int *unused;
struct s_ipv4 *ip4;
struct s_icmp *icmp;
@ -385,9 +684,11 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
return 1;
}
ip4 = (struct s_ipv4 *) packet;
icmp = (struct s_icmp *) (packet + sizeof(struct s_ipv4));
payload = (unsigned char *) (packet + sizeof(struct s_ipv4) +
ip4 = (struct s_ipv4 *) packet;
icmp = (struct s_icmp *) (packet + sizeof(struct s_ipv4));
unused = (unsigned int *) (packet + sizeof(struct s_ipv4) +
sizeof(struct s_icmp));
payload = (unsigned char *) (packet + sizeof(struct s_ipv4) +
sizeof(struct s_icmp) + 4);
/* build IPv4 packet */
@ -407,6 +708,9 @@ int icmp4_error(struct s_ipv4_addr ip_dest, unsigned char type,
icmp->code = code;
icmp->checksum = 0x0;
/* set unused area to zero */
*unused = 0x0;
/* copy the payload data */
memcpy(payload, data, payload_size);
@ -446,6 +750,7 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
unsigned short length)
{
unsigned char *packet, *payload;
unsigned int *unused;
struct s_ethernet *eth;
struct s_ipv6 *ip6;
struct s_icmp *icmp;
@ -467,6 +772,9 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
ip6 = (struct s_ipv6 *) (packet + sizeof(struct s_ethernet));
icmp = (struct s_icmp *) (packet + sizeof(struct s_ethernet) +
sizeof(struct s_ipv6));
unused = (unsigned int *) (packet + sizeof(struct s_ethernet) +
sizeof(struct s_ipv6) +
sizeof(struct s_icmp));
payload = (unsigned char *) (packet + sizeof(struct s_ethernet) +
sizeof(struct s_ipv6) +
sizeof(struct s_icmp) + 4);
@ -489,6 +797,9 @@ int icmp6_error(struct s_mac_addr mac_dest, struct s_ipv6_addr ip_dest,
icmp->code = code;
icmp->checksum = 0x0;
/* set unused area to zero */
*unused = 0x0;
/* copy the payload data */
memcpy(payload, data, payload_size);

View File

@ -25,7 +25,9 @@
/* ICMP types */
#define ICMPV4_ECHO_REPLY 0x0
#define ICMPV4_ECHO_REQUEST 0x8
#define ICMPV4_DST_UNREACHABLE 0x3
#define ICMPV4_TIME_EXCEEDED 0xb
#define ICMPV4_PARAM_PROBLEM 0xc
/* ICMPv6 types */
#define ICMPV6_DST_UNREACHABLE 0x1