1/* $FreeBSD: head/sys/contrib/ipfilter/netinet/ip_rcmd_pxy.c 145522 2005-04-25 18:43:14Z darrenr $ */
2
3/*
4 * Copyright (C) 1998-2003 by Darren Reed
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * Id: ip_rcmd_pxy.c,v 1.41.2.4 2005/02/04 10:22:55 darrenr Exp
9 *
10 * Simple RCMD transparent proxy for in-kernel use. For use with the NAT
11 * code.
12 * $FreeBSD: head/sys/contrib/ipfilter/netinet/ip_rcmd_pxy.c 145522 2005-04-25 18:43:14Z darrenr $
13 */
14
15#define IPF_RCMD_PROXY
16
17
18int ippr_rcmd_init __P((void));
19void ippr_rcmd_fini __P((void));
20int ippr_rcmd_new __P((fr_info_t *, ap_session_t *, nat_t *));
21int ippr_rcmd_out __P((fr_info_t *, ap_session_t *, nat_t *));
22int ippr_rcmd_in __P((fr_info_t *, ap_session_t *, nat_t *));
23u_short ipf_rcmd_atoi __P((char *));
24int ippr_rcmd_portmsg __P((fr_info_t *, ap_session_t *, nat_t *));
25
26static frentry_t rcmdfr;
27
28int rcmd_proxy_init = 0;
29
30
31/*
32 * RCMD application proxy initialization.
33 */
34int ippr_rcmd_init()
35{
36 bzero((char *)&rcmdfr, sizeof(rcmdfr));
37 rcmdfr.fr_ref = 1;
38 rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
39 MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock");
40 rcmd_proxy_init = 1;
41
42 return 0;
43}
44
45
46void ippr_rcmd_fini()
47{
48 if (rcmd_proxy_init == 1) {
49 MUTEX_DESTROY(&rcmdfr.fr_lock);
50 rcmd_proxy_init = 0;
51 }
52}
53
54
55/*
56 * Setup for a new RCMD proxy.
57 */
58int ippr_rcmd_new(fin, aps, nat)
59fr_info_t *fin;
60ap_session_t *aps;
61nat_t *nat;
62{
63 tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
64
65 fin = fin; /* LINT */
66 nat = nat; /* LINT */
67
68 aps->aps_psiz = sizeof(u_32_t);
69 KMALLOCS(aps->aps_data, u_32_t *, sizeof(u_32_t));
70 if (aps->aps_data == NULL) {
71#ifdef IP_RCMD_PROXY_DEBUG
72 printf("ippr_rcmd_new:KMALLOCS(%d) failed\n", sizeof(u_32_t));
73#endif
74 return -1;
75 }
76 *(u_32_t *)aps->aps_data = 0;
77 aps->aps_sport = tcp->th_sport;
78 aps->aps_dport = tcp->th_dport;
79 return 0;
80}
81
82
83/*
84 * ipf_rcmd_atoi - implement a simple version of atoi
85 */
86u_short ipf_rcmd_atoi(ptr)
87char *ptr;
88{
89 register char *s = ptr, c;
90 register u_short i = 0;
91
92 while (((c = *s++) != '\0') && ISDIGIT(c)) {
93 i *= 10;
94 i += c - '0';
95 }
96 return i;
97}
98
99
100int ippr_rcmd_portmsg(fin, aps, nat)
101fr_info_t *fin;
102ap_session_t *aps;
103nat_t *nat;
104{
105 tcphdr_t *tcp, tcph, *tcp2 = &tcph;
106 struct in_addr swip, swip2;
107 int off, dlen, nflags;
108 char portbuf[8], *s;
109 fr_info_t fi;
110 u_short sp;
111 nat_t *nat2;
112 ip_t *ip;
113 mb_t *m;
114
115 tcp = (tcphdr_t *)fin->fin_dp;
116
117 if (tcp->th_flags & TH_SYN) {
118 *(u_32_t *)aps->aps_data = htonl(ntohl(tcp->th_seq) + 1);
119 return 0;
120 }
121
122 if ((*(u_32_t *)aps->aps_data != 0) &&
123 (tcp->th_seq != *(u_32_t *)aps->aps_data))
124 return 0;
125
126 m = fin->fin_m;
127 ip = fin->fin_ip;
128 off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
129
130#ifdef __sgi
131 dlen = fin->fin_plen - off;
132#else
133 dlen = MSGDSIZE(m) - off;
134#endif
135 if (dlen <= 0)
136 return 0;
137
138 bzero(portbuf, sizeof(portbuf));
139 COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf);
140
141 portbuf[sizeof(portbuf) - 1] = '\0';
142 s = portbuf;
143 sp = ipf_rcmd_atoi(s);
144 if (sp == 0) {
145#ifdef IP_RCMD_PROXY_DEBUG
146 printf("ippr_rcmd_portmsg:sp == 0 dlen %d [%s]\n",
147 dlen, portbuf);
148#endif
149 return 0;
150 }
151
152 /*
153 * Add skeleton NAT entry for connection which will come back the
154 * other way.
155 */
156 bcopy((char *)fin, (char *)&fi, sizeof(fi));
157 fi.fin_flx |= FI_IGNORE;
158 fi.fin_data[0] = sp;
159 fi.fin_data[1] = 0;
160 if (nat->nat_dir == NAT_OUTBOUND)
161 nat2 = nat_outlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
162 nat->nat_inip, nat->nat_oip);
163 else
164 nat2 = nat_inlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
165 nat->nat_inip, nat->nat_oip);
166 if (nat2 == NULL) {
167 int slen;
168
169 slen = ip->ip_len;
170 ip->ip_len = fin->fin_hlen + sizeof(*tcp);
171 bzero((char *)tcp2, sizeof(*tcp2));
172 tcp2->th_win = htons(8192);
173 tcp2->th_sport = htons(sp);
174 tcp2->th_dport = 0; /* XXX - don't specify remote port */
175 TCP_OFF_A(tcp2, 5);
176 tcp2->th_flags = TH_SYN;
177 fi.fin_dp = (char *)tcp2;
178 fi.fin_fr = &rcmdfr;
179 fi.fin_dlen = sizeof(*tcp2);
180 fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
181 fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
182 nflags = NAT_SLAVE|IPN_TCP|SI_W_DPORT;
183
184 swip = ip->ip_src;
185 swip2 = ip->ip_dst;
186
187 if (nat->nat_dir == NAT_OUTBOUND) {
188 fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
189 ip->ip_src = nat->nat_inip;
190 } else {
191 fi.fin_fi.fi_saddr = nat->nat_oip.s_addr;
192 ip->ip_src = nat->nat_oip;
193 nflags |= NAT_NOTRULEPORT;
194 }
195
196 nat2 = nat_new(&fi, nat->nat_ptr, NULL, nflags, nat->nat_dir);
197
198 if (nat2 != NULL) {
199 (void) nat_proto(&fi, nat2, IPN_TCP);
200 nat_update(&fi, nat2, nat2->nat_ptr);
201 fi.fin_ifp = NULL;
202 if (nat->nat_dir == NAT_INBOUND) {
203 fi.fin_fi.fi_daddr = nat->nat_inip.s_addr;
204 ip->ip_dst = nat->nat_inip;
205 }
206 (void) fr_addstate(&fi, &nat2->nat_state, SI_W_DPORT);
207 if (fi.fin_state != NULL)
208 fr_statederef(&fi, (ipstate_t **)&fi.fin_state);
209 }
210 ip->ip_len = slen;
211 ip->ip_src = swip;
212 ip->ip_dst = swip2;
213 }
214 return 0;
215}
216
217
218int ippr_rcmd_out(fin, aps, nat)
219fr_info_t *fin;
220ap_session_t *aps;
221nat_t *nat;
222{
223 if (nat->nat_dir == NAT_OUTBOUND)
224 return ippr_rcmd_portmsg(fin, aps, nat);
225 return 0;
226}
227
228
229int ippr_rcmd_in(fin, aps, nat)
230fr_info_t *fin;
231ap_session_t *aps;
232nat_t *nat;
233{
234 if (nat->nat_dir == NAT_INBOUND)
235 return ippr_rcmd_portmsg(fin, aps, nat);
236 return 0;
237}