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Copy pathipfrag.c
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476 lines (380 loc) · 10 KB
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/*
* Copyright (c) 2002, 2003 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <sys/param.h>
#include <sys/types.h>
#include "config.h"
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <sys/stat.h>
#include <sys/tree.h>
#include <sys/wait.h>
#include <sys/queue.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <dnet.h>
#include <ctype.h>
#undef timeout_pending
#undef timeout_initialized
#include <event.h>
#include "honeyd.h"
#include "template.h"
#include "personality.h"
#include "ipfrag.h"
#include "pool.h"
extern struct pool *pool_pkt;
static u_char buf[IP_LEN_MAX]; /* for complete packet */
SPLAY_HEAD(fragtree, fragment) fragments;
#define DIFF(a,b) do { \
if ((a) < (b)) return -1; \
if ((a) > (b)) return 1; \
} while (0)
int
fragcompare(struct fragment *a, struct fragment *b)
{
DIFF(a->ip_src, b->ip_src);
DIFF(a->ip_dst, b->ip_dst);
DIFF(a->ip_id, b->ip_id);
DIFF(a->ip_proto, b->ip_proto);
return (0);
}
SPLAY_PROTOTYPE(fragtree, fragment, node, fragcompare);
SPLAY_GENERATE(fragtree, fragment, node, fragcompare);
TAILQ_HEAD(fragqueue, fragment) fraglru;
int nfragments;
int nfragmem;
void
ip_fragment_init(void)
{
SPLAY_INIT(&fragments);
TAILQ_INIT(&fraglru);
nfragments = 0;
nfragmem = 0;
}
struct fragment *
ip_fragment_find(ip_addr_t src, ip_addr_t dst, u_short id, u_char proto)
{
struct fragment tmp, *frag;
tmp.ip_src = src;
tmp.ip_dst = dst;
tmp.ip_id = id;
tmp.ip_proto = proto;
frag = SPLAY_FIND(fragtree, &fragments, &tmp);
if (frag != NULL) {
TAILQ_REMOVE(&fraglru, frag, next);
TAILQ_INSERT_HEAD(&fraglru, frag, next);
}
return (frag);
}
/* Free a fragment by removing it from all lists, etc... */
void
ip_fragent_free(struct fragent *ent)
{
nfragmem -= ent->size;
free(ent->data);
free(ent);
}
void
ip_fragment_free(struct fragment *tmp)
{
struct fragent *ent;
evtimer_del(tmp->timeout);
SPLAY_REMOVE(fragtree, &fragments, tmp);
TAILQ_REMOVE(&fraglru, tmp, next);
nfragments--;
for (ent = TAILQ_FIRST(&tmp->fraglist); ent;
ent = TAILQ_FIRST(&tmp->fraglist)) {
TAILQ_REMOVE(&tmp->fraglist, ent, next);
ip_fragent_free(ent);
}
free(tmp);
}
void
ip_fragment_timeout(int fd, short which, void *arg)
{
struct fragment *tmp = arg;
struct addr src;
addr_pack(&src, ADDR_TYPE_IP, IP_ADDR_BITS, &tmp->ip_src, IP_ADDR_LEN);
syslog(LOG_DEBUG, "Expiring fragment from %s, id %d",
addr_ntoa(&src), ntohs(tmp->ip_id));
ip_fragment_free(tmp);
}
void
ip_fragment_reclaim(int count)
{
struct fragment *tmp;
for (tmp = TAILQ_LAST(&fraglru, fragqueue); tmp && count;
tmp = TAILQ_LAST(&fraglru, fragqueue)) {
ip_fragment_free(tmp);
count--;
}
}
struct fragment *
ip_fragment_new(ip_addr_t src, ip_addr_t dst, u_short id, u_char proto,
enum fragpolicy pl)
{
struct fragment *tmp = NULL;
struct timeval tv = { IPFRAG_TIMEOUT, 0};
int reclaim = 0;
if (nfragmem > IPFRAG_MAX_MEM || nfragments > IPFRAG_MAX_FRAGS)
ip_fragment_reclaim(nfragments/10);
while (tmp == NULL && reclaim < 2) {
tmp = calloc(1, sizeof(struct fragment));
if (tmp == NULL) {
reclaim++;
ip_fragment_reclaim(nfragments/10);
}
}
if (tmp == NULL)
return (NULL);
tmp->ip_src = src;
tmp->ip_dst = dst;
tmp->ip_id = id;
tmp->ip_proto = proto;
tmp->fragp = pl;
TAILQ_INIT(&tmp->fraglist);
tmp->timeout = evtimer_new(libevent_base, ip_fragment_timeout, tmp);
evtimer_add(tmp->timeout, &tv);
SPLAY_INSERT(fragtree, &fragments, tmp);
TAILQ_INSERT_HEAD(&fraglru, tmp, next);
nfragments++;
return (tmp);
}
int
ip_fragment_insert(struct fragment *fragq, struct fragent *ent, short mf)
{
struct fragent *prev, *after;
struct ip_hdr *ip;
u_char *data;
u_short overlap;
u_short max;
u_short off;
u_short len;
off = ent->off;
len = ent->len;
max = off + len;
if (fragq->maxlen < max)
fragq->maxlen = max;
if (!mf)
fragq->hadlastpacket = 1;
prev = NULL;
for (after = TAILQ_FIRST(&fragq->fraglist); after;
after = TAILQ_NEXT(after, next)) {
if (off < after->off)
break;
prev = after;
}
if (prev && prev->off + prev->len > off) {
overlap = prev->off + prev->len - off;
if (overlap >= len) {
if (fragq->fragp == FRAG_NEW) {
u_char *odata = prev->data + off - prev->off;
memcpy(odata, ent->data, len);
}
goto free_fragment;
}
if (fragq->fragp == FRAG_OLD) {
u_char *odata = prev->data + prev->len - overlap;
memcpy(ent->data, odata, overlap);
}
prev->len -= overlap;
}
if (after && off + len > after->off) {
overlap = off + len - after->off;
if (overlap >= after->len) {
if (fragq->fragp == FRAG_OLD) {
u_char *ndata = ent->data + after->off - off;
memcpy(ndata, after->data, after->len);
}
/* Drop the old fragment */
TAILQ_REMOVE(&fragq->fraglist, after, next);
ip_fragent_free(after);
} else {
/* Trim the overlap */
if (fragq->fragp == FRAG_NEW) {
u_char *ndata = ent->data + len - overlap;
memcpy(after->data, ndata, overlap);
}
len -= overlap;
ent->len = len;
}
}
if (prev)
TAILQ_INSERT_AFTER(&fragq->fraglist, prev, ent, next);
else
TAILQ_INSERT_HEAD(&fragq->fraglist, ent, next);
/* Waiting for more data */
if (!fragq->hadlastpacket)
return (0);
off = 0;
TAILQ_FOREACH(ent, &fragq->fraglist, next) {
if (ent->off != off)
break;
off = ent->off + ent->len;
}
if (ent)
return (0);
/* Completely assembled */
data = buf;
ip = (struct ip_hdr *)data;
for(ent = TAILQ_FIRST(&fragq->fraglist); ent;
ent = TAILQ_FIRST(&fragq->fraglist)) {
TAILQ_REMOVE(&fragq->fraglist, ent, next);
memcpy(data, ent->data, ent->len);
data += ent->len;
ip_fragent_free(ent);
}
ip->ip_len = htons(fragq->maxlen);
ip->ip_off = 0;
ip_fragment_free(fragq);
return (1);
free_fragment:
ip_fragent_free(ent);
return (0);
}
/*
* Reassembles fragmented IP packets.
*
* Return:
* 0 - successfully reassembled
* -1 - not reassembled yet.
*/
int
ip_fragment(struct template *tmpl, struct ip_hdr *ip, u_short len,
struct ip_hdr **pip, u_short *piplen)
{
struct addr src;
struct personality *person = NULL;
struct fragment *fragq;
struct fragent *ent;
u_char *dat;
short mf;
u_short off;
u_short hlen;
enum fragpolicy fragp = FRAG_OLD;
addr_pack(&src, ADDR_TYPE_IP, IP_ADDR_BITS, &ip->ip_src, IP_ADDR_LEN);
if (tmpl != NULL && (person = tmpl->person) != NULL)
fragp = person->fragp;
if (fragp == FRAG_DROP)
goto drop;
fragq = ip_fragment_find(ip->ip_src, ip->ip_dst, ip->ip_id, ip->ip_p);
/* Nothing here for now */
off = ntohs(ip->ip_off);
if (off & IP_DF)
goto freeall;
mf = off & IP_MF;
off &= IP_OFFMASK;
off <<= 3;
dat = (u_char *)ip;
hlen = ip->ip_hl << 2;
if (mf && ((len - hlen) & 0x7))
goto freeall;
if (off) {
len -= hlen;
dat += hlen;
off += hlen;
}
if (off + len > IP_LEN_MAX || len == 0)
goto freeall;
if (fragq == NULL) {
fragq = ip_fragment_new(ip->ip_src, ip->ip_dst, ip->ip_id,
ip->ip_p, fragp);
if (fragq == NULL)
goto drop;
}
if ((ent = calloc(1, sizeof(struct fragent))) == NULL)
goto freeall;
ent->off = off;
ent->len = len;
ent->size = len;
if ((ent->data = malloc(len)) == NULL) {
free(ent);
goto freeall;
}
memcpy(ent->data, dat, len);
nfragmem += len;
syslog(LOG_DEBUG, "Received fragment from %s, id %d: %d@%d",
addr_ntoa(&src), ntohs(ip->ip_id), len, off);
if (ip_fragment_insert(fragq, ent, mf)) {
ip = (struct ip_hdr *)buf;
len = ntohs(ip->ip_len);
*pip = ip;
*piplen = len;
/* Successfully reassembled */
return (0);
}
return (-1);
freeall:
syslog(LOG_DEBUG, "%s fragment from %s, id %d: %d@%d",
fragq ? "Freeing" : "Dropping",
addr_ntoa(&src), ntohs(ip->ip_id), len, off);
if (fragq)
ip_fragment_free(fragq);
return (-1);
drop:
syslog(LOG_DEBUG, "Dropping fragment from %s", addr_ntoa(&src));
return (-1);
}
void
ip_send_fragments(u_int mtu, struct ip_hdr *ip, u_int iplen, struct spoof spoof)
{
struct ip_hdr *nip;
u_int iphlen, datlen, offset, pdatlen, size;
u_char *p;
/* Need to calculate the checksum for the protocol */
ip_checksum(ip, iplen);
iphlen = ip->ip_hl << 2;
datlen = iplen - iphlen;
pdatlen = (mtu - iphlen) & (~0x7);
offset = 0;
p = (u_char *)ip + iphlen;
while (datlen) {
nip = pool_alloc(pool_pkt);
size = datlen > pdatlen ? pdatlen : datlen;
memcpy(nip, ip, iphlen);
memcpy((u_char *)nip + iphlen, p, size);
p += size;
datlen -= size;
nip->ip_len = htons(iphlen + size);
nip->ip_off = htons((offset >> 3) | (datlen ? IP_MF : 0));
/* Send the packet:
* takes also care of deallocating this packet.
*/
honeyd_ip_send((u_char *)nip, iphlen + size, spoof);
offset += size;
}
}