1 /* $NetBSD: ip_rcmd_pxy.c,v 1.5 2013/09/14 12:06:19 martin Exp $ */
2
3 /*
4 * Copyright (C) 2012 by Darren Reed.
5 *
6 * See the IPFILTER.LICENCE file for details on licencing.
7 *
8 * Id: ip_rcmd_pxy.c,v 1.1.1.2 2012/07/22 13:45:33 darrenr Exp
9 *
10 * Simple RCMD transparent proxy for in-kernel use. For use with the NAT
11 * code.
12 */
13
14 #include <sys/cdefs.h>
15 __KERNEL_RCSID(1, "$NetBSD: ip_rcmd_pxy.c,v 1.5 2013/09/14 12:06:19 martin Exp $");
16
17 #define IPF_RCMD_PROXY
18
19 typedef struct rcmdinfo {
20 u_32_t rcmd_port; /* Port number seen */
21 u_32_t rcmd_portseq; /* Sequence number where port is first seen */
22 ipnat_t *rcmd_rule; /* Template rule for back connection */
23 } rcmdinfo_t;
24
25 void ipf_p_rcmd_main_load(void);
26 void ipf_p_rcmd_main_unload(void);
27
28 int ipf_p_rcmd_init(void);
29 void ipf_p_rcmd_fini(void);
30 void ipf_p_rcmd_del(ipf_main_softc_t *, ap_session_t *);
31 int ipf_p_rcmd_new(void *, fr_info_t *, ap_session_t *, nat_t *);
32 int ipf_p_rcmd_out(void *, fr_info_t *, ap_session_t *, nat_t *);
33 int ipf_p_rcmd_in(void *, fr_info_t *, ap_session_t *, nat_t *);
34 u_short ipf_rcmd_atoi(char *);
35 int ipf_p_rcmd_portmsg(fr_info_t *, ap_session_t *, nat_t *);
36
37 static frentry_t rcmdfr;
38
39 static int rcmd_proxy_init = 0;
40
41
42 /*
43 * RCMD application proxy initialization.
44 */
45 void
ipf_p_rcmd_main_load(void)46 ipf_p_rcmd_main_load(void)
47 {
48 bzero((char *)&rcmdfr, sizeof(rcmdfr));
49 rcmdfr.fr_ref = 1;
50 rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
51 MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock");
52 rcmd_proxy_init = 1;
53 }
54
55
56 void
ipf_p_rcmd_main_unload(void)57 ipf_p_rcmd_main_unload(void)
58 {
59 if (rcmd_proxy_init == 1) {
60 MUTEX_DESTROY(&rcmdfr.fr_lock);
61 rcmd_proxy_init = 0;
62 }
63 }
64
65
66 /*
67 * Setup for a new RCMD proxy.
68 */
69 int
ipf_p_rcmd_new(void * arg,fr_info_t * fin,ap_session_t * aps,nat_t * nat)70 ipf_p_rcmd_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
71 {
72 tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
73 rcmdinfo_t *rc;
74 ipnat_t *ipn;
75
76 fin = fin; /* LINT */
77
78 KMALLOC(rc, rcmdinfo_t *);
79 if (rc == NULL) {
80 printf("ipf_p_rcmd_new:KMALLOCS(%zu) failed\n", sizeof(*rc));
81 return -1;
82 }
83 aps->aps_sport = tcp->th_sport;
84 aps->aps_dport = tcp->th_dport;
85
86 ipn = ipf_proxy_rule_rev(nat);
87 if (ipn == NULL) {
88 KFREE(rc);
89 return -1;
90 }
91
92 aps->aps_data = rc;
93 aps->aps_psiz = sizeof(*rc);
94 bzero((char *)rc, sizeof(*rc));
95
96 rc->rcmd_rule = ipn;
97
98 return 0;
99 }
100
101
102 void
ipf_p_rcmd_del(ipf_main_softc_t * softc,ap_session_t * aps)103 ipf_p_rcmd_del(ipf_main_softc_t *softc, ap_session_t *aps)
104 {
105 rcmdinfo_t *rci;
106
107 rci = aps->aps_data;
108 if (rci != NULL) {
109 rci->rcmd_rule->in_flags |= IPN_DELETE;
110 ipf_nat_rule_deref(softc, &rci->rcmd_rule);
111 }
112 }
113
114
115 /*
116 * ipf_rcmd_atoi - implement a simple version of atoi
117 */
118 u_short
ipf_rcmd_atoi(char * ptr)119 ipf_rcmd_atoi(char *ptr)
120 {
121 char *s = ptr, c;
122 u_short i = 0;
123
124 while (((c = *s++) != '\0') && ISDIGIT(c)) {
125 i *= 10;
126 i += c - '0';
127 }
128 return i;
129 }
130
131
132 int
ipf_p_rcmd_portmsg(fr_info_t * fin,ap_session_t * aps,nat_t * nat)133 ipf_p_rcmd_portmsg(fr_info_t *fin, ap_session_t *aps, nat_t *nat)
134 {
135 tcphdr_t *tcp, tcph, *tcp2 = &tcph;
136 int off, dlen, nflags, direction;
137 ipf_main_softc_t *softc;
138 ipf_nat_softc_t *softn;
139 char portbuf[8], *s;
140 rcmdinfo_t *rc;
141 fr_info_t fi;
142 u_short sp;
143 nat_t *nat2;
144 #ifdef USE_INET6
145 ip6_t *ip6;
146 #endif
147 int tcpsz;
148 int slen = 0;
149 ip_t *ip;
150 mb_t *m;
151
152 tcp = (tcphdr_t *)fin->fin_dp;
153
154 m = fin->fin_m;
155 ip = fin->fin_ip;
156 tcpsz = TCP_OFF(tcp) << 2;
157 #ifdef USE_INET6
158 ip6 = (ip6_t *)fin->fin_ip;
159 #endif
160 softc = fin->fin_main_soft;
161 softn = softc->ipf_nat_soft;
162 off = (char *)tcp - (char *)ip + tcpsz + fin->fin_ipoff;
163
164 dlen = fin->fin_dlen - tcpsz;
165 if (dlen <= 0)
166 return 0;
167
168 rc = (rcmdinfo_t *)aps->aps_data;
169 if ((rc->rcmd_portseq != 0) &&
170 (tcp->th_seq != rc->rcmd_portseq))
171 return 0;
172
173 bzero(portbuf, sizeof(portbuf));
174 COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf);
175
176 portbuf[sizeof(portbuf) - 1] = '\0';
177 s = portbuf;
178 sp = ipf_rcmd_atoi(s);
179 if (sp == 0) {
180 #ifdef IP_RCMD_PROXY_DEBUG
181 printf("ipf_p_rcmd_portmsg:sp == 0 dlen %d [%s]\n",
182 dlen, portbuf);
183 #endif
184 return 0;
185 }
186
187 if (rc->rcmd_port != 0 && sp != rc->rcmd_port) {
188 #ifdef IP_RCMD_PROXY_DEBUG
189 printf("ipf_p_rcmd_portmsg:sp(%d) != rcmd_port(%d)\n",
190 sp, rc->rcmd_port);
191 #endif
192 return 0;
193 }
194
195 rc->rcmd_port = sp;
196 rc->rcmd_portseq = tcp->th_seq;
197
198 /*
199 * Initialise the packet info structure so we can search the NAT
200 * table to see if there already is soemthing present that matches
201 * up with what we want to add.
202 */
203 bcopy((char *)fin, (char *)&fi, sizeof(fi));
204 fi.fin_flx |= FI_IGNORE;
205 fi.fin_data[0] = 0;
206 fi.fin_data[1] = sp;
207 fi.fin_src6 = nat->nat_ndst6;
208 fi.fin_dst6 = nat->nat_nsrc6;
209
210 if (nat->nat_v[0] == 6) {
211 #ifdef USE_INET6
212 if (nat->nat_dir == NAT_OUTBOUND) {
213 nat2 = ipf_nat6_outlookup(&fi, NAT_SEARCH|IPN_TCP,
214 nat->nat_pr[1],
215 &nat->nat_osrc6.in6,
216 &nat->nat_odst6.in6);
217 } else {
218 nat2 = ipf_nat6_inlookup(&fi, NAT_SEARCH|IPN_TCP,
219 nat->nat_pr[0],
220 &nat->nat_osrc6.in6,
221 &nat->nat_odst6.in6);
222 }
223 #else
224 nat2 = (void *)-1;
225 #endif
226 } else {
227 if (nat->nat_dir == NAT_OUTBOUND) {
228 nat2 = ipf_nat_outlookup(&fi, NAT_SEARCH|IPN_TCP,
229 nat->nat_pr[1],
230 nat->nat_osrcip,
231 nat->nat_odstip);
232 } else {
233 nat2 = ipf_nat_inlookup(&fi, NAT_SEARCH|IPN_TCP,
234 nat->nat_pr[0],
235 nat->nat_osrcip,
236 nat->nat_odstip);
237 }
238 }
239 if (nat2 != NULL)
240 return APR_ERR(1);
241
242 /*
243 * Add skeleton NAT entry for connection which will come
244 * back the other way.
245 */
246
247 if (nat->nat_v[0] == 6) {
248 #ifdef USE_INET6
249 slen = ip6->ip6_plen;
250 ip6->ip6_plen = htons(sizeof(*tcp));
251 #endif
252 } else {
253 slen = ip->ip_len;
254 ip->ip_len = htons(fin->fin_hlen + sizeof(*tcp));
255 }
256
257 /*
258 * Fill out the fake TCP header with a few fields that ipfilter
259 * considers to be important.
260 */
261 bzero((char *)tcp2, sizeof(*tcp2));
262 tcp2->th_win = htons(8192);
263 TCP_OFF_A(tcp2, 5);
264 tcp2->th_flags = TH_SYN;
265
266 fi.fin_dp = (char *)tcp2;
267 fi.fin_fr = &rcmdfr;
268 fi.fin_dlen = sizeof(*tcp2);
269 fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
270 fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
271
272 if (nat->nat_dir == NAT_OUTBOUND) {
273 fi.fin_out = 0;
274 direction = NAT_INBOUND;
275 } else {
276 fi.fin_out = 1;
277 direction = NAT_OUTBOUND;
278 }
279 nflags = SI_W_SPORT|NAT_SLAVE|IPN_TCP;
280
281 MUTEX_ENTER(&softn->ipf_nat_new);
282 if (fin->fin_v == 4)
283 nat2 = ipf_nat_add(&fi, rc->rcmd_rule, NULL, nflags,
284 direction);
285 #ifdef USE_INET6
286 else
287 nat2 = ipf_nat6_add(&fi, rc->rcmd_rule, NULL, nflags,
288 direction);
289 #endif
290 MUTEX_EXIT(&softn->ipf_nat_new);
291
292 if (nat2 != NULL) {
293 (void) ipf_nat_proto(&fi, nat2, IPN_TCP);
294 MUTEX_ENTER(&nat2->nat_lock);
295 ipf_nat_update(&fi, nat2);
296 MUTEX_EXIT(&nat2->nat_lock);
297 fi.fin_ifp = NULL;
298 if (nat2->nat_dir == NAT_INBOUND)
299 fi.fin_dst6 = nat->nat_osrc6;
300 (void) ipf_state_add(softc, &fi, NULL, SI_W_SPORT);
301 }
302 if (nat->nat_v[0] == 6) {
303 #ifdef USE_INET6
304 ip6->ip6_plen = slen;
305 #endif
306 } else {
307 ip->ip_len = slen;
308 }
309 if (nat2 == NULL)
310 return APR_ERR(1);
311 return 0;
312 }
313
314
315 int
ipf_p_rcmd_out(void * arg,fr_info_t * fin,ap_session_t * aps,nat_t * nat)316 ipf_p_rcmd_out(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
317 {
318 if (nat->nat_dir == NAT_OUTBOUND)
319 return ipf_p_rcmd_portmsg(fin, aps, nat);
320 return 0;
321 }
322
323
324 int
ipf_p_rcmd_in(void * arg,fr_info_t * fin,ap_session_t * aps,nat_t * nat)325 ipf_p_rcmd_in(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat)
326 {
327 if (nat->nat_dir == NAT_INBOUND)
328 return ipf_p_rcmd_portmsg(fin, aps, nat);
329 return 0;
330 }
331