usr.sbin/ftp-proxy/filter.c

   1 /*      $OpenBSD: filter.c,v 1.6 2007/08/01 09:31:41 henning Exp $ */
   2
   3 /*
   4  * Copyright (c) 2004, 2005 Camiel Dobbelaar, <cd@sentia.nl>
   5  *
   6  * Permission to use, copy, modify, and distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <sys/ioctl.h>
  20 #include <sys/types.h>
  21 #include <sys/socket.h>
  22
  23 #include <net/if.h>
  24 #include <net/pf/pfvar.h>
  25 #include <netinet/in.h>
  26 #include <netinet/tcp.h>
  27 #include <arpa/inet.h>
  28
  29 #include <err.h>
  30 #include <errno.h>
  31 #include <fcntl.h>
  32 #include <stdio.h>
  33 #include <string.h>
  34 #include <unistd.h>
  35
  36 #include "filter.h"
  37
  38 /* From netinet/in.h, but only _KERNEL_ gets them. */
  39 #define satosin(sa)     ((struct sockaddr_in *)(sa))
  40 #define satosin6(sa)    ((struct sockaddr_in6 *)(sa))
  41
  42 enum { TRANS_FILTER = 0, TRANS_NAT, TRANS_RDR, TRANS_SIZE };
  43
  44 int prepare_rule(u_int32_t, int, struct sockaddr *, struct sockaddr *,
  45     u_int16_t);
  46 int server_lookup4(struct sockaddr_in *, struct sockaddr_in *,
  47     struct sockaddr_in *);
  48 int server_lookup6(struct sockaddr_in6 *, struct sockaddr_in6 *,
  49     struct sockaddr_in6 *);
  50
  51 static struct pfioc_pooladdr    pfp;
  52 static struct pfioc_rule        pfr;
  53 static struct pfioc_trans       pft;
  54 static struct pfioc_trans_e     pfte[TRANS_SIZE];
  55 static int dev, rule_log;
  56 static char *qname, *tagname;
  57
  58 int
  59 add_filter(u_int32_t id, u_int8_t dir, struct sockaddr *src,
  60     struct sockaddr *dst, u_int16_t d_port)
  61 {
  62         if (!src || !dst || !d_port) {
  63                 errno = EINVAL;
  64                 return (-1);
  65         }
  66
  67         if (prepare_rule(id, PF_RULESET_FILTER, src, dst, d_port) == -1)
  68                 return (-1);
  69
  70         pfr.rule.direction = dir;
  71         if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
  72                 return (-1);
  73
  74         return (0);
  75 }
  76
  77 int
  78 add_nat(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
  79     u_int16_t d_port, struct sockaddr *nat, u_int16_t nat_range_low,
  80     u_int16_t nat_range_high)
  81 {
  82         if (!src || !dst || !d_port || !nat || !nat_range_low ||
  83             (src->sa_family != nat->sa_family)) {
  84                 errno = EINVAL;
  85                 return (-1);
  86         }
  87
  88         if (prepare_rule(id, PF_RULESET_NAT, src, dst, d_port) == -1)
  89                 return (-1);
  90
  91         if (nat->sa_family == AF_INET) {
  92                 memcpy(&pfp.addr.addr.v.a.addr.v4,
  93                     &satosin(nat)->sin_addr.s_addr, 4);
  94                 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
  95         } else {
  96                 memcpy(&pfp.addr.addr.v.a.addr.v6,
  97                     &satosin6(nat)->sin6_addr.s6_addr, 16);
  98                 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
  99         }
 100         if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
 101                 return (-1);
 102
 103         pfr.rule.rpool.proxy_port[0] = nat_range_low;
 104         pfr.rule.rpool.proxy_port[1] = nat_range_high;
 105         if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
 106                 return (-1);
 107
 108         return (0);
 109 }
 110
 111 int
 112 add_rdr(u_int32_t id, struct sockaddr *src, struct sockaddr *dst,
 113     u_int16_t d_port, struct sockaddr *rdr, u_int16_t rdr_port)
 114 {
 115         if (!src || !dst || !d_port || !rdr || !rdr_port ||
 116             (src->sa_family != rdr->sa_family)) {
 117                 errno = EINVAL;
 118                 return (-1);
 119         }
 120
 121         if (prepare_rule(id, PF_RULESET_RDR, src, dst, d_port) == -1)
 122                 return (-1);
 123
 124         if (rdr->sa_family == AF_INET) {
 125                 memcpy(&pfp.addr.addr.v.a.addr.v4,
 126                     &satosin(rdr)->sin_addr.s_addr, 4);
 127                 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 4);
 128         } else {
 129                 memcpy(&pfp.addr.addr.v.a.addr.v6,
 130                     &satosin6(rdr)->sin6_addr.s6_addr, 16);
 131                 memset(&pfp.addr.addr.v.a.mask.addr8, 255, 16);
 132         }
 133         if (ioctl(dev, DIOCADDADDR, &pfp) == -1)
 134                 return (-1);
 135
 136         pfr.rule.rpool.proxy_port[0] = rdr_port;
 137         if (ioctl(dev, DIOCADDRULE, &pfr) == -1)
 138                 return (-1);
 139
 140         return (0);
 141 }
 142
 143 int
 144 do_commit(void)
 145 {
 146         if (ioctl(dev, DIOCXCOMMIT, &pft) == -1)
 147                 return (-1);
 148
 149         return (0);
 150 }
 151
 152 int
 153 do_rollback(void)
 154 {
 155         if (ioctl(dev, DIOCXROLLBACK, &pft) == -1)
 156                 return (-1);
 157
 158         return (0);
 159 }
 160
 161 void
 162 init_filter(char *opt_qname, char *opt_tagname, int opt_verbose)
 163 {
 164         struct pf_status status;
 165
 166         qname = opt_qname;
 167         tagname = opt_tagname;
 168
 169         if (opt_verbose == 1)
 170                 rule_log = PF_LOG;
 171         else if (opt_verbose == 2)
 172                 rule_log = PF_LOG_ALL;
 173
 174         dev = open("/dev/pf", O_RDWR);
 175         if (dev == -1)
 176                 err(1, "/dev/pf");
 177         if (ioctl(dev, DIOCGETSTATUS, &status) == -1)
 178                 err(1, "DIOCGETSTATUS");
 179         if (!status.running)
 180                 errx(1, "pf is disabled");
 181 }
 182
 183 int
 184 prepare_commit(u_int32_t id)
 185 {
 186         char an[PF_ANCHOR_NAME_SIZE];
 187         int i;
 188
 189         memset(&pft, 0, sizeof pft);
 190         pft.size = TRANS_SIZE;
 191         pft.esize = sizeof pfte[0];
 192         pft.array = pfte;
 193
 194         snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
 195             getpid(), id);
 196         for (i = 0; i < TRANS_SIZE; i++) {
 197                 memset(&pfte[i], 0, sizeof pfte[0]);
 198                 strlcpy(pfte[i].anchor, an, PF_ANCHOR_NAME_SIZE);
 199                 switch (i) {
 200                 case TRANS_FILTER:
 201                         pfte[i].rs_num = PF_RULESET_FILTER;
 202                         break;
 203                 case TRANS_NAT:
 204                         pfte[i].rs_num = PF_RULESET_NAT;
 205                         break;
 206                 case TRANS_RDR:
 207                         pfte[i].rs_num = PF_RULESET_RDR;
 208                         break;
 209                 default:
 210                         errno = EINVAL;
 211                         return (-1);
 212                 }
 213         }
 214
 215         if (ioctl(dev, DIOCXBEGIN, &pft) == -1)
 216                 return (-1);
 217
 218         return (0);
 219 }
 220
 221 int
 222 prepare_rule(u_int32_t id, int rs_num, struct sockaddr *src,
 223     struct sockaddr *dst, u_int16_t d_port)
 224 {
 225         char an[PF_ANCHOR_NAME_SIZE];
 226
 227         if ((src->sa_family != AF_INET && src->sa_family != AF_INET6) ||
 228             (src->sa_family != dst->sa_family)) {
 229                 errno = EPROTONOSUPPORT;
 230                 return (-1);
 231         }
 232
 233         memset(&pfp, 0, sizeof pfp);
 234         memset(&pfr, 0, sizeof pfr);
 235         snprintf(an, PF_ANCHOR_NAME_SIZE, "%s/%d.%d", FTP_PROXY_ANCHOR,
 236             getpid(), id);
 237         strlcpy(pfp.anchor, an, PF_ANCHOR_NAME_SIZE);
 238         strlcpy(pfr.anchor, an, PF_ANCHOR_NAME_SIZE);
 239
 240         switch (rs_num) {
 241         case PF_RULESET_FILTER:
 242                 pfr.ticket = pfte[TRANS_FILTER].ticket;
 243                 break;
 244         case PF_RULESET_NAT:
 245                 pfr.ticket = pfte[TRANS_NAT].ticket;
 246                 break;
 247         case PF_RULESET_RDR:
 248                 pfr.ticket = pfte[TRANS_RDR].ticket;
 249                 break;
 250         default:
 251                 errno = EINVAL;
 252                 return (-1);
 253         }
 254         if (ioctl(dev, DIOCBEGINADDRS, &pfp) == -1)
 255                 return (-1);
 256         pfr.pool_ticket = pfp.ticket;
 257
 258         /* Generic for all rule types. */
 259         pfr.rule.af = src->sa_family;
 260         pfr.rule.proto = IPPROTO_TCP;
 261         pfr.rule.src.addr.type = PF_ADDR_ADDRMASK;
 262         pfr.rule.dst.addr.type = PF_ADDR_ADDRMASK;
 263         if (src->sa_family == AF_INET) {
 264                 memcpy(&pfr.rule.src.addr.v.a.addr.v4,
 265                     &satosin(src)->sin_addr.s_addr, 4);
 266                 memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 4);
 267                 memcpy(&pfr.rule.dst.addr.v.a.addr.v4,
 268                     &satosin(dst)->sin_addr.s_addr, 4);
 269                 memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 4);
 270         } else {
 271                 memcpy(&pfr.rule.src.addr.v.a.addr.v6,
 272                     &satosin6(src)->sin6_addr.s6_addr, 16);
 273                 memset(&pfr.rule.src.addr.v.a.mask.addr8, 255, 16);
 274                 memcpy(&pfr.rule.dst.addr.v.a.addr.v6,
 275                     &satosin6(dst)->sin6_addr.s6_addr, 16);
 276                 memset(&pfr.rule.dst.addr.v.a.mask.addr8, 255, 16);
 277         }
 278         pfr.rule.dst.port_op = PF_OP_EQ;
 279         pfr.rule.dst.port[0] = htons(d_port);
 280         if (tagname != NULL)
 281                 strlcpy(pfr.rule.tagname, tagname, sizeof pfr.rule.tagname);
 282
 283         switch (rs_num) {
 284         case PF_RULESET_FILTER:
 285                 /*
 286                  * pass quick [log] inet[6] proto tcp \
 287                  *     from $src to $dst port = $d_port flags S/SA keep state
 288                  *     (max 1) [queue qname]
 289                  */
 290                 pfr.rule.action = PF_PASS;
 291                 pfr.rule.quick = 1;
 292                 pfr.rule.log = rule_log;
 293                 pfr.rule.keep_state = 1;
 294                 pfr.rule.flags = TH_SYN;
 295                 pfr.rule.flagset = (TH_SYN|TH_ACK);
 296                 pfr.rule.max_states = 1;
 297                 if (qname != NULL)
 298                         strlcpy(pfr.rule.qname, qname, sizeof pfr.rule.qname);
 299                 break;
 300         case PF_RULESET_NAT:
 301                 /*
 302                  * nat inet[6] proto tcp from $src to $dst port $d_port -> $nat
 303                  */
 304                 pfr.rule.action = PF_NAT;
 305                 break;
 306         case PF_RULESET_RDR:
 307                 /*
 308                  * rdr inet[6] proto tcp from $src to $dst port $d_port -> $rdr
 309                  */
 310                 pfr.rule.action = PF_RDR;
 311                 break;
 312         default:
 313                 errno = EINVAL;
 314                 return (-1);
 315         }
 316
 317         return (0);
 318 }
 319
 320 int
 321 server_lookup(struct sockaddr *client, struct sockaddr *proxy,
 322     struct sockaddr *server)
 323 {
 324         if (client->sa_family == AF_INET)
 325                 return (server_lookup4(satosin(client), satosin(proxy),
 326                     satosin(server)));
 327
 328         if (client->sa_family == AF_INET6)
 329                 return (server_lookup6(satosin6(client), satosin6(proxy),
 330                     satosin6(server)));
 331
 332         errno = EPROTONOSUPPORT;
 333         return (-1);
 334 }
 335
 336 int
 337 server_lookup4(struct sockaddr_in *client, struct sockaddr_in *proxy,
 338     struct sockaddr_in *server)
 339 {
 340         struct pfioc_natlook pnl;
 341
 342         memset(&pnl, 0, sizeof pnl);
 343         pnl.direction = PF_OUT;
 344         pnl.af = AF_INET;
 345         pnl.proto = IPPROTO_TCP;
 346         memcpy(&pnl.saddr.v4, &client->sin_addr.s_addr, sizeof pnl.saddr.v4);
 347         memcpy(&pnl.daddr.v4, &proxy->sin_addr.s_addr, sizeof pnl.daddr.v4);
 348         pnl.sport = client->sin_port;
 349         pnl.dport = proxy->sin_port;
 350
 351         if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
 352                 return (-1);
 353
 354         memset(server, 0, sizeof(struct sockaddr_in));
 355         server->sin_len = sizeof(struct sockaddr_in);
 356         server->sin_family = AF_INET;
 357         memcpy(&server->sin_addr.s_addr, &pnl.rdaddr.v4,
 358             sizeof server->sin_addr.s_addr);
 359         server->sin_port = pnl.rdport;
 360
 361         return (0);
 362 }
 363
 364 int
 365 server_lookup6(struct sockaddr_in6 *client, struct sockaddr_in6 *proxy,
 366     struct sockaddr_in6 *server)
 367 {
 368         struct pfioc_natlook pnl;
 369
 370         memset(&pnl, 0, sizeof pnl);
 371         pnl.direction = PF_OUT;
 372         pnl.af = AF_INET6;
 373         pnl.proto = IPPROTO_TCP;
 374         memcpy(&pnl.saddr.v6, &client->sin6_addr.s6_addr, sizeof pnl.saddr.v6);
 375         memcpy(&pnl.daddr.v6, &proxy->sin6_addr.s6_addr, sizeof pnl.daddr.v6);
 376         pnl.sport = client->sin6_port;
 377         pnl.dport = proxy->sin6_port;
 378
 379         if (ioctl(dev, DIOCNATLOOK, &pnl) == -1)
 380                 return (-1);
 381
 382         memset(server, 0, sizeof(struct sockaddr_in6));
 383         server->sin6_len = sizeof(struct sockaddr_in6);
 384         server->sin6_family = AF_INET6;
 385         memcpy(&server->sin6_addr.s6_addr, &pnl.rdaddr.v6,
 386             sizeof server->sin6_addr);
 387         server->sin6_port = pnl.rdport;
 388
 389         return (0);
 390 }