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analyzer-d4-pibs
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analyzer-d4-pibs/bin/pibs.c

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/*
* pibs - Passive Identification of BackScatter
*
* Copyright (C) 2019 Gerard Wagener
* Copyright (C) 2019 CIRCL Computer Incident Response Center Luxembourg
* (SMILE gie).
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <assert.h>
#include <string.h>
#include <pcap/pcap.h>
#include <wtap.h>
#include <wtap-int.h>
#include <unistd.h>
#include <signal.h>
#include <netinet/ip.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <hiredis/hiredis.h>
//TODO test other values
#define NBINS 1024 //Number of bins
#define NBINITEMS 255 //Number of items per bin
#define SZBIN 4
#define SZUUID 40
#define SZKEY 1024
#define SZSERVER 1024
#define NBINSCALE 2 // Scaling factor of the entire datastructure
#define HDBG(...) if (HASHDEBUG) fprintf(stderr, __VA_ARGS__)
#define ERR_ATTACH_NOT_EMPTY 11
#define ERR_NO_SHMID_FILE 12
typedef struct pibs_header_s {
uint8_t magic [4];
uint8_t version;
//Put some useful stuff here
uint32_t next_item;
uint32_t bin_offset;
uint64_t data_size;
uint32_t max_item;
uint8_t padding [3];
} pibs_header_t;
/* TODO This can squezed. Timestamp can be expressed on 8 bits i.e. relative
* minutes
* IP can be represented with 16 bits ipaddr = ip / bin_size
* Not sure if space can be saved in usual cases
*/
typedef struct item_s {
uint32_t timestamp;
uint32_t next_item;
uint32_t ipaddr;
} item_t;
/* Need to hash source IP addresses and record first seen and flags */
typedef struct pibs_s {
int errno_copy;
int errno_pibs;
char *filename;
char *uuid;
char *key;
char *server;
uint16_t port;
int should_dump_table;
int show_backscatter;
int show_stats;
int should_create_shm;
int should_attach;
//TODO use self contained data structure that can be easily serialized
//Put data structure in an entire block to easier serialize
uint8_t *data;
uint32_t next_block;
uint32_t next_item;
uint32_t bin_offset;
uint64_t data_size;
uint32_t* bin_table;
uint32_t max_item;
item_t* items;
int shmid;
char shmid_file [FILENAME_MAX];
} pibs_t;
int load_shmid_file(pibs_t* pibs)
{
FILE* fp;
if (pibs->shmid_file[0]) {
fp = fopen(pibs->shmid_file,"r");
if (fp) {
//FIXME check file
fscanf(fp, "%d", &pibs->shmid);
return pibs->shmid;
}
} else {
pibs->errno_pibs = ERR_NO_SHMID_FILE;
}
return -1;
}
//TODO when attaching the next_item must be recovered if results
//of previous runs need to be increased
int pibs_shmat(pibs_t* pibs)
{
/* FIXME init function needs to break up in two functions. One that
* initializes internal pibs structures as cli options etc
* a second one for describing the data itself, size of bin_table
* number of items etc.
*/
if (pibs->data) {
free(pibs->data);
pibs->data = NULL;
}
if (pibs->data) {
pibs->errno_pibs = ERR_ATTACH_NOT_EMPTY;
printf("TEST Data is not null\n");
return -1;
}
if (!pibs->shmid_file[0]) {
pibs->errno_pibs = ERR_NO_SHMID_FILE;
return -1;
}
if (load_shmid_file(pibs) > 0) {
pibs->data = shmat(pibs->shmid, NULL, SHM_RND);
if ( (int) pibs->data == -1) {
pibs->errno_copy = errno;
} else {
return 1;
}
}
// Something did not work
return -1;
}
int pibs_shmget(pibs_t* pibs)
{
FILE* fp;
pibs->shmid = shmget(IPC_PRIVATE, pibs->data_size, IPC_CREAT | 0600);
if (pibs->shmid < 0) {
pibs->errno_copy = errno;
}
if (pibs->shmid_file[0]){
fp = fopen(pibs->shmid_file, "w");
if (fp) {
fprintf(fp,"%d",pibs->shmid);
fclose(fp);
}
//TODO error handling
}
//TODO attach to it and bzero it
//setup the tables
return pibs->shmid;
}
/*
* Returns -1 if not found
* returns last timestamp if found
*/
int_fast64_t get_last_timestamp(pibs_t* pibs, uint32_t ip)
{
uint32_t idx;
uint32_t i;
//TODO explore alternative hashing functions
//https://stackoverflow.com/questions/664014/what-integer-hash-function-are-good-that-accepts-an-integer-hash-key/12996028#12996028
idx = ip % NBINS;
HDBG("[TS] Checking for IP %x at index = %d\n", ip, idx);
i = pibs->bin_table[idx];
while (i){
if (pibs->items[i].ipaddr == ip) {
HDBG("[TS] Found item %x at position %d\n", ip , i);
return pibs->items[i].timestamp;
}
i = pibs->items[i].next_item;
}
HDBG("[TS] IP: %x was not found return -1\n",ip);
return -1;
}
void insert_ip(pibs_t* pibs, uint32_t ip, uint32_t ts)
{
uint32_t idx;
uint32_t i;
uint32_t parent;
idx = ip % NBINS;
HDBG("[INS] Lookup IP address %x. Hashed value: %d\n", ip, idx);
parent = 0;
if (pibs->bin_table[idx]){
// There is already someone in the bin
i = pibs->bin_table[idx];
HDBG("[INS] Starting searching at position %d\n", i);
do {
HDBG("[INS] Iterating items at index %d. Current position: %d.\
Next position = %d\n",
idx,i,pibs->items[i].next_item);
HDBG("[INS] Checking IP at address %p\n",&pibs->items[i]);
if (pibs->items[i].ipaddr == ip) {
HDBG("[INS] Found item %x at position %d\n", ip , i);
HDBG("[INS] New timestamp for ip %x is %d\n",ip,ts);
pibs->items[i].timestamp = ts;
return;
}
parent = i;
i = pibs->items[i].next_item;
} while (i != 0 );
HDBG("[INS] The IP %x was not found in the item list, last parent %d\n",
ip, parent);
}
// The IP was not found in an item list or the hashed value wsa not present
// in the bin table, so create a new item
pibs->next_item++;
if (pibs->next_item > pibs->max_item) {
printf("FIXME run out of memory. Do something better than abort\n");
//Go through old timestamps and keep linked list of stuff that can be
//reused or do kind of defragmentation
abort();
}
if (pibs->bin_table[idx] == 0) {
pibs->bin_table[idx] = pibs->next_item;
}
HDBG("[INS] Insert ip %x at position %d, parent = %d\n", ip,
pibs->next_item,parent);
pibs->items[pibs->next_item].ipaddr = ip;
pibs->items[pibs->next_item].timestamp = ts;
if (parent) {
pibs->items[parent].next_item = pibs->next_item;
}
}
void process_frame(pibs_t* pibs, wtap *wth,
uint8_t *buf, size_t length)
{
struct ip* ipv4;
uint32_t ip;
struct tcphdr* tcp;
int_fast64_t lastseen;
if (length < sizeof(struct ip)) {
return;
}
ipv4 = (struct ip*)buf;
// Focus only on TCP packets
if (ipv4->ip_p != 6)
return;
tcp = (struct tcphdr*)(buf+sizeof(struct ip));
memcpy(&ip, &ipv4->ip_src, 4);
// Record only source ips where syn flag is set
// TODO check other connection establishment alternatives
if (tcp->th_flags == 2 ){
insert_ip(pibs, ip, wth->rec.ts.secs);
return;
}
lastseen = get_last_timestamp(pibs, ip);
if (lastseen > 0){
HDBG("IP %x %s was already seen before at %ld. Time difference %ld.\n"
, ip, inet_ntoa(ipv4->ip_src), lastseen, wth->rec.ts.secs-lastseen);
return;
}
// TODO keep these IPs in a hashtable and rank them
if (pibs->show_backscatter) {
printf("Potential backscatter. IP. %s. TCP flags: %d. Source port:%d \n",
inet_ntoa(ipv4->ip_src), tcp->th_flags, ntohs(tcp->th_sport));
}
//TODO relative time
//Purge old ips?
}
void process_file(pibs_t* pibs)
{
wtap *wth;
int err;
char *errinfo;
gint64 data_offset;
int ethertype;
guint8 *buf;
fprintf(stderr,"Processing %s\n",pibs->filename);
wth = wtap_open_offline ( pibs->filename, WTAP_TYPE_AUTO, (int*)&err,
(char**)&errinfo, FALSE);
if (wth) {
/* Loop over the packets and adjust the headers */
while (wtap_read(wth, &err, &errinfo, &data_offset)) {
if (wth->rec.rec_type == REC_TYPE_PACKET) {
if (wth->rec.tsprec == WTAP_TSPREC_USEC){
if (wth->rec.rec_header.packet_header.caplen < 14) {
fprintf(stderr,"Packet too small, skip\n");
continue;
}
}
buf = wth->rec_data->data;
ethertype = buf[12] << 8 | buf[13];
// TODO Focus on IPv4 only
if (ethertype == 0x0800) {
process_frame(pibs, wth, buf+14, wth->rec.rec_header.packet_header.caplen -14);
}
}
}
wtap_close(wth);
fprintf(stderr,"[INFO] Processing of filename %s done\n",pibs->filename);
}else{
fprintf(stderr, "[ERROR] Could not open filename %s,cause=%s\n",pibs->filename,
wtap_strerror(err));
}
}
pibs_t* init(void)
{
pibs_t *pibs;
wtap_init(FALSE);
pibs=calloc(sizeof(pibs_t),1);
//TODO check if size is correct
pibs->data_size = sizeof(pibs_header_t) + NBINSCALE * NBINS * SZBIN * NBINITEMS * sizeof(item_t);
pibs->data = calloc(pibs->data_size,1);
pibs->filename = calloc(FILENAME_MAX,1);
pibs->uuid = calloc(SZUUID,1);
pibs->key = calloc(SZKEY,1);
pibs->server = calloc(SZSERVER,1);
printf("#Internal look up structure size in bytes: %ld\n", pibs->data_size);
// Build header
pibs->data[0]='P';
pibs->data[1] = 'I';
pibs->data[2] = 'B';
pibs->data[3] = 'S';
pibs->data[4] = 1; //version 1
pibs->next_block = sizeof(pibs_header_t);
pibs->bin_offset = pibs->next_block;
printf("#data address is %p\n",pibs->data);
pibs->bin_table = (uint32_t*)(pibs->data+pibs->bin_offset);
printf("#bin_table address is %p\n", pibs->bin_table);
// Create bins
pibs->next_block+=SZBIN * NBINS;
printf("#next block %d\n", pibs->next_block);
pibs->items = (item_t*)(pibs->data+pibs->next_block);
pibs->next_item = 0;
printf("#items are address %p\n", pibs->items);
pibs->max_item = NBINS * NBINITEMS;
printf("#max_item: %d\n", pibs->max_item);
return pibs;
}
void pibs_dump_raw(pibs_t* pibs)
{
int i;
printf("#RAW table dump\n");
printf("#Index next_item\n");
printf("#BINs\n");
for (i=0; i< NBINS; i++) {
printf("%d %d\n", i, pibs->bin_table[i]);
}
printf("#ITEMS\n");
printf("#Index next_item, timestamp, ipaddr\n");
for (i=0; i < NBINITEMS * NBINS; i++) {
printf("%d %d %d %x\n", i, pibs->items[i].next_item,
pibs->items[i].timestamp,
pibs->items[i].ipaddr);
}
}
void pibs_dump_stats(pibs_t* pibs)
{
int i;
int j;
int cnt;
uint64_t sum;
sum = 0;
printf("#Bin table\n");
printf("#Bin number, Item offset, number of items\n");
for (i=0; i < NBINS; i++) {
j= pibs->bin_table[i];
cnt = 0;
while (j) {
cnt++;
j=pibs->items[j].next_item;
}
sum+=cnt;
printf("%d %d %d\n", i, pibs->bin_table[i], cnt);
}
printf("#Number of unique IP addresses: %ld\n", sum);
}
int main(int argc, char* argv[])
{
int opt;
pibs_t* pibs;
pibs = init();
fprintf(stderr, "[INFO] pid = %d\n",(int)getpid());
while ((opt = getopt(argc, argv, "r:dbsni:au:z:p:")) != -1) {
switch (opt) {
case 'r':
strncpy(pibs->filename, optarg, FILENAME_MAX);
break;
case 'd':
pibs->should_dump_table = 1;
break;
case 'b':
pibs->show_backscatter = 1;
break;
case 's':
pibs->show_stats = 1;
break;
case 'n':
pibs->should_create_shm = 1;
break;
case 'i':
strncpy(pibs->shmid_file, optarg, FILENAME_MAX);
break;
case 'a':
pibs->should_attach = 1;
break;
case 'u':
strncpy(pibs->uuid, optarg, SZUUID);
break;
case 'z':
strncpy(pibs->server,optarg, SZSERVER);
break;
case 'p':
pibs->port=atoi(optarg);
break;
default: /* '?' */
fprintf(stderr, "[ERROR] Invalid command line was specified\n");
}
}
if (pibs->should_create_shm) {
pibs_shmget(pibs);
if (pibs->shmid >0){
printf("Create a new shared memory segment %d\n", pibs->shmid);
} else {
printf("Failed to get shared memory segment. Cause = %s\n",
strerror(pibs->errno_copy));
}
}
if (pibs->should_attach) {
if (pibs_shmat(pibs) > 0 ) {
printf("Attached to shared memory segment %d\n", pibs->shmid);
} else {
printf("Failed to attach to shared memory segment. System error:%s\n",
strerror(pibs->errno_copy));
return EXIT_FAILURE;
}
}
if (pibs->uuid[0]) {
snprintf(pibs->key, SZKEY, "analyzer:1:%s",pibs->uuid);
if ((pibs->server[0] == 0) || (pibs->port == 0)) {
fprintf(stderr,"Redis parameter server and port are incomplete. Use -z and -p options.\n");
return EXIT_FAILURE;
}
}
if (pibs->filename[0]) {
process_file(pibs);
}
if (pibs->should_dump_table){
pibs_dump_raw(pibs);
}
if (pibs->show_stats){
pibs_dump_stats(pibs);
}
return EXIT_FAILURE;
}
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