1 /*
2 * Copyright (C) 2012 by Darren Reed.
3 *
4 * See the IPFILTER.LICENCE file for details on licencing.
5 *
6 * $Id$
7 */
8
9 #define IPF_IRC_PROXY
10
11 #define IPF_IRCBUFSZ 96 /* This *MUST* be >= 64! */
12
13
14 void ipf_p_irc_main_load(void);
15 void ipf_p_irc_main_unload(void);
16 int ipf_p_irc_new(void *, fr_info_t *, ap_session_t *, nat_t *);
17 int ipf_p_irc_out(void *, fr_info_t *, ap_session_t *, nat_t *);
18 int ipf_p_irc_send(fr_info_t *, nat_t *);
19 int ipf_p_irc_complete(ircinfo_t *, char *, size_t);
20 u_short ipf_irc_atoi(char **);
21
22 static frentry_t ircnatfr;
23
24 int irc_proxy_init = 0;
25
26
27 /*
28 * Initialize local structures.
29 */
30 void
ipf_p_irc_main_load(void)31 ipf_p_irc_main_load(void)
32 {
33 bzero((char *)&ircnatfr, sizeof(ircnatfr));
34 ircnatfr.fr_ref = 1;
35 ircnatfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
36 MUTEX_INIT(&ircnatfr.fr_lock, "IRC proxy rule lock");
37 irc_proxy_init = 1;
38 }
39
40
41 void
ipf_p_irc_main_unload(void)42 ipf_p_irc_main_unload(void)
43 {
44 if (irc_proxy_init == 1) {
45 MUTEX_DESTROY(&ircnatfr.fr_lock);
46 irc_proxy_init = 0;
47 }
48 }
49
50
51 const char *ipf_p_irc_dcctypes[] = {
52 "CHAT ", /* CHAT chat ipnumber portnumber */
53 "SEND ", /* SEND filename ipnumber portnumber */
54 "MOVE ",
55 "TSEND ",
56 "SCHAT ",
57 NULL,
58 };
59
60
61 /*
62 * :A PRIVMSG B :^ADCC CHAT chat 0 0^A\r\n
63 * PRIVMSG B ^ADCC CHAT chat 0 0^A\r\n
64 */
65
66
67 int
ipf_p_irc_complete(ircinfo_t * ircp,char * buf,size_t len)68 ipf_p_irc_complete(ircinfo_t *ircp, char *buf, size_t len)
69 {
70 register char *s, c;
71 register size_t i;
72 u_32_t l;
73 int j, k;
74
75 ircp->irc_ipnum = 0;
76 ircp->irc_port = 0;
77
78 if (len < 31)
79 return (0);
80 s = buf;
81 c = *s++;
82 i = len - 1;
83
84 if ((c != ':') && (c != 'P'))
85 return (0);
86
87 if (c == ':') {
88 /*
89 * Loosely check that the source is a nickname of some sort
90 */
91 s++;
92 c = *s;
93 ircp->irc_snick = s;
94 if (!ISALPHA(c))
95 return (0);
96 i--;
97 for (c = *s; !ISSPACE(c) && (i > 0); i--)
98 c = *s++;
99 if (i < 31)
100 return (0);
101 if (c != 'P')
102 return (0);
103 } else
104 ircp->irc_snick = NULL;
105
106 /*
107 * Check command string
108 */
109 if (strncmp(s, "PRIVMSG ", 8))
110 return (0);
111 i -= 8;
112 s += 8;
113 c = *s;
114 ircp->irc_dnick = s;
115
116 /*
117 * Loosely check that the destination is a nickname of some sort
118 */
119 if (!ISALPHA(c))
120 return (0);
121 for (; !ISSPACE(c) && (i > 0); i--)
122 c = *s++;
123 if (i < 20)
124 return (0);
125 s++,
126 i--;
127
128 /*
129 * Look for a ^A to start the DCC
130 */
131 c = *s;
132 if (c == ':') {
133 s++;
134 c = *s;
135 }
136
137 if (strncmp(s, "\001DCC ", 4))
138 return (0);
139
140 i -= 4;
141 s += 4;
142
143 /*
144 * Check for a recognised DCC command
145 */
146 for (j = 0, k = 0; ipf_p_irc_dcctypes[j]; j++) {
147 k = MIN(strlen(ipf_p_irc_dcctypes[j]), i);
148 if (!strncmp(ipf_p_irc_dcctypes[j], s, k))
149 break;
150 }
151 if (!ipf_p_irc_dcctypes[j])
152 return (0);
153
154 ircp->irc_type = s;
155 i -= k;
156 s += k;
157
158 if (i < 11)
159 return (0);
160
161 /*
162 * Check for the arg
163 */
164 c = *s;
165 if (ISSPACE(c))
166 return (0);
167 ircp->irc_arg = s;
168 for (; (c != ' ') && (c != '\001') && (i > 0); i--)
169 c = *s++;
170
171 if (c == '\001') /* In reality a ^A can quote another ^A...*/
172 return (0);
173
174 if (i < 5)
175 return (0);
176
177 s++;
178 i--;
179 c = *s;
180 if (!ISDIGIT(c))
181 return (0);
182 ircp->irc_addr = s;
183 /*
184 * Get the IP#
185 */
186 for (l = 0; ISDIGIT(c) && (i > 0); i--) {
187 l *= 10;
188 l += c - '0';
189 c = *s++;
190 }
191
192 if (i < 4)
193 return (0);
194
195 if (c != ' ')
196 return (0);
197
198 ircp->irc_ipnum = l;
199 s++;
200 i--;
201 c = *s;
202 if (!ISDIGIT(c))
203 return (0);
204 /*
205 * Get the port#
206 */
207 for (l = 0; ISDIGIT(c) && (i > 0); i--) {
208 l *= 10;
209 l += c - '0';
210 c = *s++;
211 }
212 if (i < 3)
213 return (0);
214 if (strncmp(s, "\001\r\n", 3))
215 return (0);
216 s += 3;
217 ircp->irc_len = s - buf;
218 ircp->irc_port = l;
219 return (1);
220 }
221
222
223 int
ipf_p_irc_new(void * arg,fr_info_t * fin,ap_session_t * aps,nat_t * nat __unused)224 ipf_p_irc_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat __unused)
225 {
226 ircinfo_t *irc;
227
228 if (fin->fin_v != 4)
229 return (-1);
230
231 KMALLOC(irc, ircinfo_t *);
232 if (irc == NULL)
233 return (-1);
234
235 aps->aps_data = irc;
236 aps->aps_psiz = sizeof(ircinfo_t);
237
238 bzero((char *)irc, sizeof(*irc));
239 return (0);
240 }
241
242
243 int
ipf_p_irc_send(fr_info_t * fin,nat_t * nat)244 ipf_p_irc_send(fr_info_t *fin, nat_t *nat)
245 {
246 char ctcpbuf[IPF_IRCBUFSZ], newbuf[IPF_IRCBUFSZ];
247 tcphdr_t *tcp, tcph, *tcp2 = &tcph;
248 int off, inc = 0, i, dlen;
249 ipf_main_softc_t *softc;
250 size_t nlen = 0, olen;
251 struct in_addr swip;
252 u_short a5, sp;
253 ircinfo_t *irc;
254 fr_info_t fi;
255 nat_t *nat2;
256 u_int a1;
257 ip_t *ip;
258 mb_t *m;
259 #if SOLARIS
260 mb_t *m1;
261 #endif
262 softc = fin->fin_main_soft;
263
264 m = fin->fin_m;
265 ip = fin->fin_ip;
266 tcp = (tcphdr_t *)fin->fin_dp;
267 bzero(ctcpbuf, sizeof(ctcpbuf));
268 off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
269
270 dlen = MSGDSIZE(m) - off;
271 if (dlen <= 0)
272 return (0);
273 COPYDATA(m, off, MIN(sizeof(ctcpbuf), dlen), ctcpbuf);
274
275 if (dlen <= 0)
276 return (0);
277 ctcpbuf[sizeof(ctcpbuf) - 1] = '\0';
278 *newbuf = '\0';
279
280 irc = nat->nat_aps->aps_data;
281 if (ipf_p_irc_complete(irc, ctcpbuf, dlen) == 0)
282 return (0);
283
284 /*
285 * check that IP address in the DCC reply is the same as the
286 * sender of the command - prevents use for port scanning.
287 */
288 if (irc->irc_ipnum != ntohl(nat->nat_osrcaddr))
289 return (0);
290
291 a5 = irc->irc_port;
292
293 /*
294 * Calculate new address parts for the DCC command
295 */
296 a1 = ntohl(ip->ip_src.s_addr);
297 olen = irc->irc_len;
298 i = irc->irc_addr - ctcpbuf;
299 i++;
300 (void) strncpy(newbuf, ctcpbuf, i);
301 /* DO NOT change these! */
302 (void) snprintf(newbuf, sizeof(newbuf), "%u %u\001\r\n", a1, a5);
303
304 nlen = strlen(newbuf);
305 inc = nlen - olen;
306
307 if ((inc + fin->fin_plen) > 65535)
308 return (0);
309
310 #if SOLARIS
311 for (m1 = m; m1->b_cont; m1 = m1->b_cont)
312 ;
313 if ((inc > 0) && (m1->b_datap->db_lim - m1->b_wptr < inc)) {
314 mblk_t *nm;
315
316 /* alloc enough to keep same trailer space for lower driver */
317 nm = allocb(nlen, BPRI_MED);
318 PANIC((!nm),("ipf_p_irc_out: allocb failed"));
319
320 nm->b_band = m1->b_band;
321 nm->b_wptr += nlen;
322
323 m1->b_wptr -= olen;
324 PANIC((m1->b_wptr < m1->b_rptr),
325 ("ipf_p_irc_out: cannot handle fragmented data block"));
326
327 linkb(m1, nm);
328 } else {
329 # if SOLARIS && defined(ICK_VALID)
330 if (m1->b_datap->db_struiolim == m1->b_wptr)
331 m1->b_datap->db_struiolim += inc;
332 m1->b_datap->db_struioflag &= ~STRUIO_IP;
333 # endif
334 m1->b_wptr += inc;
335 }
336 #else
337 if (inc < 0)
338 m_adj(m, inc);
339 /* the mbuf chain will be extended if necessary by m_copyback() */
340 #endif
341 COPYBACK(m, off, nlen, newbuf);
342 fin->fin_flx |= FI_DOCKSUM;
343
344 if (inc != 0) {
345 #if SOLARIS
346 register u_32_t sum1, sum2;
347
348 sum1 = fin->fin_plen;
349 sum2 = fin->fin_plen + inc;
350
351 /* Because ~1 == -2, We really need ~1 == -1 */
352 if (sum1 > sum2)
353 sum2--;
354 sum2 -= sum1;
355 sum2 = (sum2 & 0xffff) + (sum2 >> 16);
356
357 ipf_fix_outcksum(0, &ip->ip_sum, sum2, 0);
358 #endif
359 fin->fin_plen += inc;
360 ip->ip_len = htons(fin->fin_plen);
361 fin->fin_dlen += inc;
362 }
363
364 /*
365 * Add skeleton NAT entry for connection which will come back the
366 * other way.
367 */
368 sp = htons(a5);
369 /*
370 * Don't allow the PORT command to specify a port < 1024 due to
371 * security crap.
372 */
373 if (ntohs(sp) < 1024)
374 return (0);
375
376 /*
377 * The server may not make the connection back from port 20, but
378 * it is the most likely so use it here to check for a conflicting
379 * mapping.
380 */
381 bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
382 fi.fin_data[0] = sp;
383 fi.fin_data[1] = fin->fin_data[1];
384 nat2 = ipf_nat_outlookup(fin, IPN_TCP, nat->nat_pr[1], nat->nat_nsrcip,
385 ip->ip_dst);
386 if (nat2 == NULL) {
387 #ifdef USE_MUTEXES
388 ipf_nat_softc_t *softn = softc->ipf_nat_soft;
389 #endif
390
391 bcopy((caddr_t)fin, (caddr_t)&fi, sizeof(fi));
392 bzero((char *)tcp2, sizeof(*tcp2));
393 tcp2->th_win = htons(8192);
394 tcp2->th_sport = sp;
395 tcp2->th_dport = 0; /* XXX - don't specify remote port */
396 fi.fin_data[0] = ntohs(sp);
397 fi.fin_data[1] = 0;
398 fi.fin_dp = (char *)tcp2;
399 fi.fin_fr = &ircnatfr;
400 fi.fin_dlen = sizeof(*tcp2);
401 fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
402 swip = ip->ip_src;
403 ip->ip_src = nat->nat_nsrcip;
404 MUTEX_ENTER(&softn->ipf_nat_new);
405 nat2 = ipf_nat_add(&fi, nat->nat_ptr, NULL,
406 NAT_SLAVE|IPN_TCP|SI_W_DPORT, NAT_OUTBOUND);
407 MUTEX_EXIT(&softn->ipf_nat_new);
408 if (nat2 != NULL) {
409 (void) ipf_nat_proto(&fi, nat2, 0);
410 MUTEX_ENTER(&nat2->nat_lock);
411 ipf_nat_update(&fi, nat2);
412 MUTEX_EXIT(&nat2->nat_lock);
413
414 (void) ipf_state_add(softc, &fi, NULL, SI_W_DPORT);
415 }
416 ip->ip_src = swip;
417 }
418 return (inc);
419 }
420
421
422 int
ipf_p_irc_out(void * arg,fr_info_t * fin,ap_session_t * aps __unused,nat_t * nat)423 ipf_p_irc_out(void *arg, fr_info_t *fin, ap_session_t *aps __unused, nat_t *nat)
424 {
425 return (ipf_p_irc_send(fin, nat));
426 }
427