blob: 8b545b81e3f205c89e3a2033d002547bc61a73a1 [file] [log] [blame] [raw]
/*
* Copyright (C) 2011 by Darren Reed.
*
* Simple PPTP transparent proxy for in-kernel use. For use with the NAT
* code.
*
* $Id$
*
*/
#define IPF_PPTP_PROXY
/*
* PPTP proxy
*/
typedef struct pptp_side {
u_32_t pptps_nexthdr;
u_32_t pptps_next;
int pptps_state;
int pptps_gothdr;
int pptps_len;
int pptps_bytes;
char *pptps_wptr;
char pptps_buffer[512];
} pptp_side_t;
typedef struct pptp_pxy {
nat_t *pptp_nat;
struct ipstate *pptp_state;
u_short pptp_call[2];
pptp_side_t pptp_side[2];
ipnat_t *pptp_rule;
} pptp_pxy_t;
typedef struct pptp_hdr {
u_short pptph_len;
u_short pptph_type;
u_32_t pptph_cookie;
} pptp_hdr_t;
#define PPTP_MSGTYPE_CTL 1
#define PPTP_MTCTL_STARTREQ 1
#define PPTP_MTCTL_STARTREP 2
#define PPTP_MTCTL_STOPREQ 3
#define PPTP_MTCTL_STOPREP 4
#define PPTP_MTCTL_ECHOREQ 5
#define PPTP_MTCTL_ECHOREP 6
#define PPTP_MTCTL_OUTREQ 7
#define PPTP_MTCTL_OUTREP 8
#define PPTP_MTCTL_INREQ 9
#define PPTP_MTCTL_INREP 10
#define PPTP_MTCTL_INCONNECT 11
#define PPTP_MTCTL_CLEAR 12
#define PPTP_MTCTL_DISCONNECT 13
#define PPTP_MTCTL_WANERROR 14
#define PPTP_MTCTL_LINKINFO 15
void ipf_p_pptp_main_load __P((void));
void ipf_p_pptp_main_unload __P((void));
int ipf_p_pptp_new __P((void *, fr_info_t *, ap_session_t *, nat_t *));
void ipf_p_pptp_del __P((ipf_main_softc_t *, ap_session_t *));
int ipf_p_pptp_inout __P((void *, fr_info_t *, ap_session_t *, nat_t *));
void ipf_p_pptp_donatstate __P((fr_info_t *, nat_t *, pptp_pxy_t *));
int ipf_p_pptp_message __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *));
int ipf_p_pptp_nextmessage __P((fr_info_t *, nat_t *, pptp_pxy_t *, int));
int ipf_p_pptp_mctl __P((fr_info_t *, nat_t *, pptp_pxy_t *, pptp_side_t *));
static frentry_t pptpfr;
static int pptp_proxy_init = 0;
static int ipf_p_pptp_debug = 0;
static int ipf_p_pptp_gretimeout = IPF_TTLVAL(120); /* 2 minutes */
/*
* PPTP application proxy initialization.
*/
void
ipf_p_pptp_main_load()
{
bzero((char *)&pptpfr, sizeof(pptpfr));
pptpfr.fr_ref = 1;
pptpfr.fr_age[0] = ipf_p_pptp_gretimeout;
pptpfr.fr_age[1] = ipf_p_pptp_gretimeout;
pptpfr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
MUTEX_INIT(&pptpfr.fr_lock, "PPTP proxy rule lock");
pptp_proxy_init = 1;
}
void
ipf_p_pptp_main_unload()
{
if (pptp_proxy_init == 1) {
MUTEX_DESTROY(&pptpfr.fr_lock);
pptp_proxy_init = 0;
}
}
/*
* Setup for a new PPTP proxy.
*
* NOTE: The printf's are broken up with %s in them to prevent them being
* optimised into puts statements on FreeBSD (this doesn't exist in the kernel)
*/
int
ipf_p_pptp_new(arg, fin, aps, nat)
void *arg;
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
pptp_pxy_t *pptp;
ipnat_t *ipn;
ipnat_t *np;
int size;
ip_t *ip;
ip = fin->fin_ip;
np = nat->nat_ptr;
size = np->in_size;
if (ipf_nat_outlookup(fin, 0, IPPROTO_GRE, nat->nat_osrcip,
ip->ip_dst) != NULL) {
if (ipf_p_pptp_debug > 0)
printf("ipf_p_pptp_new: GRE session already exists\n");
return -1;
}
KMALLOC(pptp, pptp_pxy_t *);
if (pptp == NULL) {
if (ipf_p_pptp_debug > 0)
printf("ipf_p_pptp_new: malloc for aps_data failed\n");
return -1;
}
KMALLOCS(ipn, ipnat_t *, size);
if (ipn == NULL) {
KFREE(pptp);
return -1;
}
aps->aps_data = pptp;
aps->aps_psiz = sizeof(*pptp);
bzero((char *)pptp, sizeof(*pptp));
bzero((char *)ipn, size);
pptp->pptp_rule = ipn;
/*
* Create NAT rule against which the tunnel/transport mapping is
* created. This is required because the current NAT rule does not
* describe GRE but TCP instead.
*/
ipn->in_size = size;
ipn->in_ifps[0] = fin->fin_ifp;
ipn->in_apr = NULL;
ipn->in_use = 1;
ipn->in_hits = 1;
ipn->in_ippip = 1;
ipn->in_snip = ntohl(nat->nat_nsrcaddr);
ipn->in_nsrcaddr = fin->fin_saddr;
ipn->in_dnip = ntohl(nat->nat_ndstaddr);
ipn->in_ndstaddr = nat->nat_ndstaddr;
ipn->in_redir = np->in_redir;
ipn->in_osrcaddr = nat->nat_osrcaddr;
ipn->in_odstaddr = nat->nat_odstaddr;
ipn->in_osrcmsk = 0xffffffff;
ipn->in_nsrcmsk = 0xffffffff;
ipn->in_odstmsk = 0xffffffff;
ipn->in_ndstmsk = 0xffffffff;
ipn->in_flags = (np->in_flags | IPN_PROXYRULE);
MUTEX_INIT(&ipn->in_lock, "pptp proxy NAT rule");
ipn->in_namelen = np->in_namelen;
bcopy(np->in_names, ipn->in_ifnames, ipn->in_namelen);
ipn->in_ifnames[0] = np->in_ifnames[0];
ipn->in_ifnames[1] = np->in_ifnames[1];
ipn->in_pr[0] = IPPROTO_GRE;
ipn->in_pr[1] = IPPROTO_GRE;
pptp->pptp_side[0].pptps_wptr = pptp->pptp_side[0].pptps_buffer;
pptp->pptp_side[1].pptps_wptr = pptp->pptp_side[1].pptps_buffer;
return 0;
}
void
ipf_p_pptp_donatstate(fin, nat, pptp)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
{
ipf_main_softc_t *softc = fin->fin_main_soft;
fr_info_t fi;
grehdr_t gre;
nat_t *nat2;
u_char p;
ip_t *ip;
ip = fin->fin_ip;
p = ip->ip_p;
nat2 = pptp->pptp_nat;
if ((nat2 == NULL) || (pptp->pptp_state == NULL)) {
bcopy((char *)fin, (char *)&fi, sizeof(fi));
bzero((char *)&gre, sizeof(gre));
fi.fin_fi.fi_p = IPPROTO_GRE;
fi.fin_fr = &pptpfr;
if ((nat->nat_dir == NAT_OUTBOUND && fin->fin_out) ||
(nat->nat_dir == NAT_INBOUND && !fin->fin_out)) {
fi.fin_data[0] = pptp->pptp_call[0];
fi.fin_data[1] = pptp->pptp_call[1];
} else {
fi.fin_data[0] = pptp->pptp_call[1];
fi.fin_data[1] = pptp->pptp_call[0];
}
ip = fin->fin_ip;
ip->ip_p = IPPROTO_GRE;
fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
fi.fin_flx |= FI_IGNORE;
fi.fin_dp = &gre;
gre.gr_flags = htons(1 << 13);
fi.fin_fi.fi_saddr = nat->nat_osrcaddr;
fi.fin_fi.fi_daddr = nat->nat_odstaddr;
}
/*
* Update NAT timeout/create NAT if missing.
*/
if (nat2 != NULL)
ipf_queueback(softc->ipf_ticks, &nat2->nat_tqe);
else {
#ifdef USE_MUTEXES
ipf_nat_softc_t *softn = softc->ipf_nat_soft;
#endif
MUTEX_ENTER(&softn->ipf_nat_new);
nat2 = ipf_nat_add(&fi, pptp->pptp_rule, &pptp->pptp_nat,
NAT_SLAVE, nat->nat_dir);
MUTEX_EXIT(&softn->ipf_nat_new);
if (nat2 != NULL) {
(void) ipf_nat_proto(&fi, nat2, 0);
MUTEX_ENTER(&nat2->nat_lock);
ipf_nat_update(&fi, nat2);
MUTEX_EXIT(&nat2->nat_lock);
}
}
READ_ENTER(&softc->ipf_state);
if (pptp->pptp_state != NULL) {
ipf_queueback(softc->ipf_ticks, &pptp->pptp_state->is_sti);
RWLOCK_EXIT(&softc->ipf_state);
} else {
RWLOCK_EXIT(&softc->ipf_state);
if (nat2 != NULL) {
if (nat->nat_dir == NAT_INBOUND)
fi.fin_fi.fi_daddr = nat2->nat_ndstaddr;
else
fi.fin_fi.fi_saddr = nat2->nat_osrcaddr;
}
fi.fin_ifp = NULL;
(void) ipf_state_add(softc, &fi, &pptp->pptp_state, 0);
}
ip->ip_p = p;
return;
}
/*
* Try and build up the next PPTP message in the TCP stream and if we can
* build it up completely (fits in our buffer) then pass it off to the message
* parsing function.
*/
int
ipf_p_pptp_nextmessage(fin, nat, pptp, rev)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
int rev;
{
static const char *funcname = "ipf_p_pptp_nextmessage";
pptp_side_t *pptps;
u_32_t start, end;
pptp_hdr_t *hdr;
tcphdr_t *tcp;
int dlen, off;
u_short len;
char *msg;
tcp = fin->fin_dp;
dlen = fin->fin_dlen - (TCP_OFF(tcp) << 2);
start = ntohl(tcp->th_seq);
pptps = &pptp->pptp_side[rev];
off = (char *)tcp - (char *)fin->fin_ip + (TCP_OFF(tcp) << 2) +
fin->fin_ipoff;
if (dlen <= 0)
return 0;
/*
* If the complete data packet is before what we expect to see
* "next", just ignore it as the chances are we've already seen it.
* The next if statement following this one really just causes packets
* ahead of what we've seen to be dropped, implying that something in
* the middle went missing and we want to see that first.
*/
end = start + dlen;
if (pptps->pptps_next > end && pptps->pptps_next > start)
return 0;
if (pptps->pptps_next != start) {
if (ipf_p_pptp_debug > 5)
printf("%s: next (%x) != start (%x)\n", funcname,
pptps->pptps_next, start);
return -1;
}
msg = (char *)fin->fin_dp + (TCP_OFF(tcp) << 2);
while (dlen > 0) {
off += pptps->pptps_bytes;
if (pptps->pptps_gothdr == 0) {
/*
* PPTP has an 8 byte header that inclues the cookie.
* The start of every message should include one and
* it should match 1a2b3c4d. Byte order is ignored,
* deliberately, when printing out the error.
*/
len = MIN(8 - pptps->pptps_bytes, dlen);
COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
pptps->pptps_bytes += len;
pptps->pptps_wptr += len;
hdr = (pptp_hdr_t *)pptps->pptps_buffer;
if (pptps->pptps_bytes == 8) {
pptps->pptps_next += 8;
if (ntohl(hdr->pptph_cookie) != 0x1a2b3c4d) {
if (ipf_p_pptp_debug > 1)
printf("%s: bad cookie (%x)\n",
funcname,
hdr->pptph_cookie);
return -1;
}
}
dlen -= len;
msg += len;
off += len;
pptps->pptps_gothdr = 1;
len = ntohs(hdr->pptph_len);
pptps->pptps_len = len;
pptps->pptps_nexthdr += len;
/*
* If a message is too big for the buffer, just set
* the fields for the next message to come along.
* The messages defined in RFC 2637 will not exceed
* 512 bytes (in total length) so this is likely a
* bad data packet, anyway.
*/
if (len > sizeof(pptps->pptps_buffer)) {
if (ipf_p_pptp_debug > 3)
printf("%s: message too big (%d)\n",
funcname, len);
pptps->pptps_next = pptps->pptps_nexthdr;
pptps->pptps_wptr = pptps->pptps_buffer;
pptps->pptps_gothdr = 0;
pptps->pptps_bytes = 0;
pptps->pptps_len = 0;
break;
}
}
len = MIN(pptps->pptps_len - pptps->pptps_bytes, dlen);
COPYDATA(fin->fin_m, off, len, pptps->pptps_wptr);
pptps->pptps_bytes += len;
pptps->pptps_wptr += len;
pptps->pptps_next += len;
if (pptps->pptps_len > pptps->pptps_bytes)
break;
ipf_p_pptp_message(fin, nat, pptp, pptps);
pptps->pptps_wptr = pptps->pptps_buffer;
pptps->pptps_gothdr = 0;
pptps->pptps_bytes = 0;
pptps->pptps_len = 0;
start += len;
msg += len;
dlen -= len;
}
return 0;
}
/*
* handle a complete PPTP message
*/
int
ipf_p_pptp_message(fin, nat, pptp, pptps)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
pptp_side_t *pptps;
{
pptp_hdr_t *hdr = (pptp_hdr_t *)pptps->pptps_buffer;
switch (ntohs(hdr->pptph_type))
{
case PPTP_MSGTYPE_CTL :
ipf_p_pptp_mctl(fin, nat, pptp, pptps);
break;
default :
break;
}
return 0;
}
/*
* handle a complete PPTP control message
*/
int
ipf_p_pptp_mctl(fin, nat, pptp, pptps)
fr_info_t *fin;
nat_t *nat;
pptp_pxy_t *pptp;
pptp_side_t *pptps;
{
u_short *buffer = (u_short *)(pptps->pptps_buffer);
pptp_side_t *pptpo;
if (pptps == &pptp->pptp_side[0])
pptpo = &pptp->pptp_side[1];
else
pptpo = &pptp->pptp_side[0];
/*
* Breakout to handle all the various messages. Most are just state
* transition.
*/
switch (ntohs(buffer[4]))
{
case PPTP_MTCTL_STARTREQ :
pptps->pptps_state = PPTP_MTCTL_STARTREQ;
break;
case PPTP_MTCTL_STARTREP :
if (pptpo->pptps_state == PPTP_MTCTL_STARTREQ)
pptps->pptps_state = PPTP_MTCTL_STARTREP;
break;
case PPTP_MTCTL_STOPREQ :
pptps->pptps_state = PPTP_MTCTL_STOPREQ;
break;
case PPTP_MTCTL_STOPREP :
if (pptpo->pptps_state == PPTP_MTCTL_STOPREQ)
pptps->pptps_state = PPTP_MTCTL_STOPREP;
break;
case PPTP_MTCTL_ECHOREQ :
pptps->pptps_state = PPTP_MTCTL_ECHOREQ;
break;
case PPTP_MTCTL_ECHOREP :
if (pptpo->pptps_state == PPTP_MTCTL_ECHOREQ)
pptps->pptps_state = PPTP_MTCTL_ECHOREP;
break;
case PPTP_MTCTL_OUTREQ :
pptps->pptps_state = PPTP_MTCTL_OUTREQ;
break;
case PPTP_MTCTL_OUTREP :
if (pptpo->pptps_state == PPTP_MTCTL_OUTREQ) {
pptps->pptps_state = PPTP_MTCTL_OUTREP;
pptp->pptp_call[0] = buffer[7];
pptp->pptp_call[1] = buffer[6];
ipf_p_pptp_donatstate(fin, nat, pptp);
}
break;
case PPTP_MTCTL_INREQ :
pptps->pptps_state = PPTP_MTCTL_INREQ;
break;
case PPTP_MTCTL_INREP :
if (pptpo->pptps_state == PPTP_MTCTL_INREQ) {
pptps->pptps_state = PPTP_MTCTL_INREP;
pptp->pptp_call[0] = buffer[7];
pptp->pptp_call[1] = buffer[6];
ipf_p_pptp_donatstate(fin, nat, pptp);
}
break;
case PPTP_MTCTL_INCONNECT :
pptps->pptps_state = PPTP_MTCTL_INCONNECT;
break;
case PPTP_MTCTL_CLEAR :
pptps->pptps_state = PPTP_MTCTL_CLEAR;
break;
case PPTP_MTCTL_DISCONNECT :
pptps->pptps_state = PPTP_MTCTL_DISCONNECT;
break;
case PPTP_MTCTL_WANERROR :
pptps->pptps_state = PPTP_MTCTL_WANERROR;
break;
case PPTP_MTCTL_LINKINFO :
pptps->pptps_state = PPTP_MTCTL_LINKINFO;
break;
}
return 0;
}
/*
* For outgoing PPTP packets. refresh timeouts for NAT & state entries, if
* we can. If they have disappeared, recreate them.
*/
int
ipf_p_pptp_inout(arg, fin, aps, nat)
void *arg;
fr_info_t *fin;
ap_session_t *aps;
nat_t *nat;
{
pptp_pxy_t *pptp;
tcphdr_t *tcp;
int rev;
if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
rev = 1;
else if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
rev = 1;
else
rev = 0;
tcp = (tcphdr_t *)fin->fin_dp;
if ((tcp->th_flags & TH_OPENING) == TH_OPENING) {
pptp = (pptp_pxy_t *)aps->aps_data;
pptp->pptp_side[1 - rev].pptps_next = ntohl(tcp->th_ack);
pptp->pptp_side[1 - rev].pptps_nexthdr = ntohl(tcp->th_ack);
pptp->pptp_side[rev].pptps_next = ntohl(tcp->th_seq) + 1;
pptp->pptp_side[rev].pptps_nexthdr = ntohl(tcp->th_seq) + 1;
}
return ipf_p_pptp_nextmessage(fin, nat, (pptp_pxy_t *)aps->aps_data,
rev);
}
/*
* clean up after ourselves.
*/
void
ipf_p_pptp_del(softc, aps)
ipf_main_softc_t *softc;
ap_session_t *aps;
{
pptp_pxy_t *pptp;
pptp = aps->aps_data;
if (pptp != NULL) {
/*
* Don't bother changing any of the NAT structure details,
* *_del() is on a callback from aps_free(), from nat_delete()
*/
READ_ENTER(&softc->ipf_state);
if (pptp->pptp_state != NULL) {
ipf_state_setpending(softc, pptp->pptp_state);
}
RWLOCK_EXIT(&softc->ipf_state);
if (pptp->pptp_nat != NULL)
ipf_nat_setpending(softc, pptp->pptp_nat);
pptp->pptp_rule->in_flags |= IPN_DELETE;
ipf_nat_rule_deref(softc, &pptp->pptp_rule);
}
}