ip_tftp_pxy.c revision 1.2
1 /* $NetBSD: ip_tftp_pxy.c,v 1.2 2012/03/23 20:39:50 christos Exp $ */ 2 3 /* 4 * Copyright (C) 2010 by Darren Reed. 5 * 6 * See the IPFILTER.LICENCE file for details on licencing. 7 * 8 * Id: ip_tftp_pxy.c,v 2.1.2.2 2012/01/26 05:29:13 darrenr Exp 9 */ 10 11 #define IPF_TFTP_PROXY 12 13 void ipf_p_tftp_main_load(void); 14 void ipf_p_tftp_main_unload(void); 15 int ipf_p_tftp_new(void *, fr_info_t *, ap_session_t *, nat_t *); 16 int ipf_p_tftp_out(void *, fr_info_t *, ap_session_t *, nat_t *); 17 int ipf_p_tftp_in(void *, fr_info_t *, ap_session_t *, nat_t *); 18 int ipf_p_tftp_client(fr_info_t *, ap_session_t *, nat_t *); 19 int ipf_p_tftp_server(fr_info_t *, ap_session_t *, nat_t *); 20 int ipf_p_tftp_backchannel(fr_info_t *, ap_session_t *, nat_t *); 21 22 static frentry_t tftpfr; 23 24 int tftp_proxy_init = 0; 25 26 typedef struct tftpinfo { 27 nat_t *ti_datanat; 28 ipstate_t *ti_datastate; 29 int ti_lastcmd; 30 int ti_nextblk; 31 int ti_lastblk; 32 int ti_lasterror; 33 char ti_filename[80]; 34 } tftpinfo_t; 35 36 #define TFTP_CMD_READ 1 37 #define TFTP_CMD_WRITE 2 38 #define TFTP_CMD_DATA 3 39 #define TFTP_CMD_ACK 4 40 #define TFTP_CMD_ERROR 5 41 42 43 /* 44 * TFTP application proxy initialization. 45 */ 46 void 47 ipf_p_tftp_main_load(void) 48 { 49 50 bzero((char *)&tftpfr, sizeof(tftpfr)); 51 tftpfr.fr_ref = 1; 52 tftpfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE; 53 MUTEX_INIT(&tftpfr.fr_lock, "TFTP proxy rule lock"); 54 tftp_proxy_init = 1; 55 } 56 57 58 void 59 ipf_p_tftp_main_unload(void) 60 { 61 62 if (tftp_proxy_init == 1) { 63 MUTEX_DESTROY(&tftpfr.fr_lock); 64 tftp_proxy_init = 0; 65 } 66 } 67 68 69 int 70 ipf_p_tftp_out(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) 71 { 72 73 if (nat->nat_dir == NAT_OUTBOUND) 74 return ipf_p_tftp_client(fin, aps, nat); 75 return ipf_p_tftp_server(fin, aps, nat); 76 } 77 78 79 int 80 ipf_p_tftp_in(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) 81 { 82 83 if (nat->nat_dir == NAT_INBOUND) 84 return ipf_p_tftp_client(fin, aps, nat); 85 return ipf_p_tftp_server(fin, aps, nat); 86 } 87 88 89 int 90 ipf_p_tftp_new(void *arg, fr_info_t *fin, ap_session_t *aps, nat_t *nat) 91 { 92 udphdr_t *udp; 93 tftpinfo_t *ti; 94 95 KMALLOC(ti, tftpinfo_t *); 96 if (ti == NULL) 97 return -1; 98 99 aps->aps_data = ti; 100 aps->aps_psiz = sizeof(*ti); 101 ti->ti_lastcmd = 0; 102 103 nat = nat; /* LINT */ 104 fin = fin; /* LINT */ 105 106 udp = (udphdr_t *)fin->fin_dp; 107 aps->aps_sport = udp->uh_sport; 108 aps->aps_dport = udp->uh_dport; 109 return 0; 110 } 111 112 113 /* 114 * Setup for a new TFTP proxy. 115 */ 116 int 117 ipf_p_tftp_backchannel(fr_info_t *fin, ap_session_t *aps, nat_t *nat) 118 { 119 ipf_main_softc_t *softc = fin->fin_main_soft; 120 #ifdef USE_MUTEXES 121 ipf_nat_softc_t *softn = softc->ipf_nat_soft; 122 #endif 123 struct in_addr swip,swip2; 124 tftpinfo_t *ti; 125 udphdr_t *udp; 126 fr_info_t fi; 127 nat_t *nat2; 128 129 ti = aps->aps_data; 130 udp = (udphdr_t *)fin->fin_dp; 131 /* 132 * Add skeleton NAT entry for connection which will come back the 133 * other way. 134 */ 135 bcopy((char *)fin, (char *)&fi, sizeof(fi)); 136 fi.fin_flx |= FI_IGNORE; 137 fi.fin_data[1] = 0; 138 if (nat->nat_dir == NAT_OUTBOUND) 139 nat2 = ipf_nat_outlookup(&fi, NAT_SEARCH|IPN_UDP, 140 nat->nat_pr[0], nat->nat_osrcip, 141 nat->nat_odstip); 142 else 143 nat2 = ipf_nat_inlookup(&fi, NAT_SEARCH|IPN_UDP, 144 nat->nat_pr[0], nat->nat_nsrcip, 145 nat->nat_odstip); 146 if (nat2 == NULL) { 147 u_short slen; 148 int nflags; 149 ip_t *ip; 150 151 ip = fin->fin_ip; 152 slen = ip->ip_len; 153 ip->ip_len = htons(fin->fin_hlen + sizeof(*udp)); 154 bzero((char *)udp, sizeof(*udp)); 155 udp->uh_sport = htons(fi.fin_data[0]); 156 udp->uh_dport = 0; /* XXX - don't specify remote port */ 157 udp->uh_ulen = 0; 158 udp->uh_sum = 0; 159 fi.fin_dp = (char *)udp; 160 fi.fin_fr = &tftpfr; 161 fi.fin_dlen = sizeof(*udp); 162 fi.fin_plen = fi.fin_hlen + sizeof(*udp); 163 fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE; 164 nflags = NAT_SLAVE|IPN_UDP|SI_W_DPORT; 165 166 swip = ip->ip_src; 167 swip2 = ip->ip_dst; 168 fi.fin_fi.fi_saddr = nat->nat_osrcaddr; 169 ip->ip_src = nat->nat_osrcip; 170 fi.fin_fi.fi_daddr = nat->nat_odstaddr; 171 ip->ip_dst = nat->nat_odstip; 172 173 if (nat->nat_dir == NAT_INBOUND) 174 nflags |= NAT_NOTRULEPORT; 175 176 MUTEX_ENTER(&softn->ipf_nat_new); 177 nat2 = ipf_nat_add(&fi, nat->nat_ptr, &ti->ti_datanat, 178 nflags, nat->nat_dir); 179 MUTEX_EXIT(&softn->ipf_nat_new); 180 if (nat2 != NULL) { 181 (void) ipf_nat_proto(&fi, nat2, IPN_UDP); 182 ipf_nat_update(&fi, nat2); 183 fi.fin_ifp = NULL; 184 if (ipf_state_add(softc, &fi, &ti->ti_datastate, 185 SI_W_DPORT) != 0) { 186 ipf_nat_setpending(softc, nat2); 187 } 188 } 189 ip->ip_len = slen; 190 ip->ip_src = swip; 191 ip->ip_dst = swip2; 192 return 0; 193 } 194 return -1; 195 } 196 197 198 int 199 ipf_p_tftp_client(fr_info_t *fin, ap_session_t *aps, nat_t *nat) 200 { 201 u_char *msg, *s, *t; 202 tftpinfo_t *ti; 203 u_short opcode; 204 udphdr_t *udp; 205 int len; 206 207 if (fin->fin_dlen < 4) 208 return 0; 209 210 ti = aps->aps_data; 211 msg = fin->fin_dp; 212 msg += sizeof(udphdr_t); 213 opcode = (msg[0] << 8) | msg[1]; 214 215 switch (opcode) 216 { 217 case TFTP_CMD_READ : 218 case TFTP_CMD_WRITE : 219 if (fin->fin_out != 0) 220 return -1; 221 len = fin->fin_dlen - sizeof(*udp) - 2; 222 if (len > sizeof(ti->ti_filename) - 1) 223 len = sizeof(ti->ti_filename) - 1; 224 s = msg + 2; 225 for (t = (u_char *)ti->ti_filename; (len > 0); len--, s++) { 226 *t++ = *s; 227 if (*s == '\0') 228 break; 229 } 230 break; 231 default : 232 return -1; 233 } 234 235 ti = aps->aps_data; 236 ti->ti_lastcmd = opcode; 237 return 0; 238 } 239 240 241 int 242 ipf_p_tftp_server(fr_info_t *fin, ap_session_t *aps, nat_t *nat) 243 { 244 tftpinfo_t *ti; 245 u_short opcode; 246 u_short arg; 247 u_char *msg; 248 249 if (fin->fin_dlen < 4) 250 return 0; 251 252 ti = aps->aps_data; 253 msg = fin->fin_dp; 254 msg += sizeof(udphdr_t); 255 arg = (msg[2] << 8) | msg[3]; 256 opcode = (msg[0] << 8) | msg[1]; 257 258 switch (opcode) 259 { 260 case TFTP_CMD_ACK : 261 /* This proxy should not see any ACKS for DATA blocks */ 262 if (fin->fin_out != 1) 263 return -1; 264 if ((arg == 0) && 265 (ti->ti_lastcmd == TFTP_CMD_READ || 266 ti->ti_lastcmd == TFTP_CMD_WRITE)) 267 ipf_p_tftp_backchannel(fin, aps, nat); 268 ti->ti_lastblk = arg; 269 break; 270 case TFTP_CMD_ERROR : 271 if (fin->fin_out != 1) 272 return -1; 273 ti->ti_lasterror = arg; 274 break; 275 default : 276 return -1; 277 } 278 279 ti->ti_lastcmd = opcode; 280 return 0; 281 } 282
Indexes created Mon Sep 29 21:09:56 GMT 2025