ip_rcmd_pxy.c revision 1.3
1 /* $NetBSD: ip_rcmd_pxy.c,v 1.3 2012/07/22 14:27:51 darrenr 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 1.3 2012/07/22 14:27:51 darrenr 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 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 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 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 ipnat_t *np; 76 int size; 77 78 fin = fin; /* LINT */ 79 80 np = nat->nat_ptr; 81 size = np->in_size; 82 KMALLOC(rc, rcmdinfo_t *); 83 if (rc == NULL) { 84 printf("ipf_p_rcmd_new:KMALLOCS(%zu) failed\n", sizeof(*rc)); 85 return -1; 86 } 87 aps->aps_sport = tcp->th_sport; 88 aps->aps_dport = tcp->th_dport; 89 90 ipn = ipf_proxy_rule_rev(nat); 91 if (ipn == NULL) { 92 KFREE(rc); 93 return -1; 94 } 95 96 aps->aps_data = rc; 97 aps->aps_psiz = sizeof(*rc); 98 bzero((char *)rc, sizeof(*rc)); 99 100 rc->rcmd_rule = ipn; 101 102 return 0; 103 } 104 105 106 void 107 ipf_p_rcmd_del(ipf_main_softc_t *softc, ap_session_t *aps) 108 { 109 rcmdinfo_t *rci; 110 111 rci = aps->aps_data; 112 if (rci != NULL) { 113 rci->rcmd_rule->in_flags |= IPN_DELETE; 114 ipf_nat_rule_deref(softc, &rci->rcmd_rule); 115 } 116 } 117 118 119 /* 120 * ipf_rcmd_atoi - implement a simple version of atoi 121 */ 122 u_short 123 ipf_rcmd_atoi(char *ptr) 124 { 125 char *s = ptr, c; 126 u_short i = 0; 127 128 while (((c = *s++) != '\0') && ISDIGIT(c)) { 129 i *= 10; 130 i += c - '0'; 131 } 132 return i; 133 } 134 135 136 int 137 ipf_p_rcmd_portmsg(fr_info_t *fin, ap_session_t *aps, nat_t *nat) 138 { 139 tcphdr_t *tcp, tcph, *tcp2 = &tcph; 140 int off, dlen, nflags, direction; 141 ipf_main_softc_t *softc; 142 ipf_nat_softc_t *softn; 143 char portbuf[8], *s; 144 rcmdinfo_t *rc; 145 fr_info_t fi; 146 u_short sp; 147 nat_t *nat2; 148 ip6_t *ip6; 149 int tcpsz; 150 int slen; 151 ip_t *ip; 152 mb_t *m; 153 154 tcp = (tcphdr_t *)fin->fin_dp; 155 156 m = fin->fin_m; 157 ip = fin->fin_ip; 158 tcpsz = TCP_OFF(tcp) << 2; 159 ip6 = (ip6_t *)fin->fin_ip; 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 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 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
Indexes created Tue Sep 30 07:10:03 GMT 2025