src/ip/Intercept.cc

   1 /*
   2  * DEBUG: section 89    NAT / IP Interception
   3  * AUTHOR: Robert Collins
   4  * AUTHOR: Amos Jeffries
   5  *
   6  * SQUID Web Proxy Cache          http://www.squid-cache.org/
   7  * ----------------------------------------------------------
   8  *
   9  *  Squid is the result of efforts by numerous individuals from
  10  *  the Internet community; see the CONTRIBUTORS file for full
  11  *  details.   Many organizations have provided support for Squid's
  12  *  development; see the SPONSORS file for full details.  Squid is
  13  *  Copyrighted (C) 2001 by the Regents of the University of
  14  *  California; see the COPYRIGHT file for full details.  Squid
  15  *  incorporates software developed and/or copyrighted by other
  16  *  sources; see the CREDITS file for full details.
  17  *
  18  *  This program is free software; you can redistribute it and/or modify
  19  *  it under the terms of the GNU General Public License as published by
  20  *  the Free Software Foundation; either version 2 of the License, or
  21  *  (at your option) any later version.
  22  *
  23  *  This program is distributed in the hope that it will be useful,
  24  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  25  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26  *  GNU General Public License for more details.
  27  *
  28  *  You should have received a copy of the GNU General Public License
  29  *  along with this program; if not, write to the Free Software
  30  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  31  *
  32  */
  33 #include "squid.h"
  34 #include "comm/Connection.h"
  35 #include "ip/Intercept.h"
  36 #include "fde.h"
  37
  38 #if IPF_TRANSPARENT
  39
  40 #if HAVE_SYS_IOCTL_H
  41 #include <sys/ioctl.h>
  42 #endif
  43 #if HAVE_NETINET_TCP_H
  44 #include <netinet/tcp.h>
  45 #endif
  46 #if HAVE_NET_IF_H
  47 #include <net/if.h>
  48 #endif
  49 #if HAVE_IPL_H
  50 #include <ipl.h>
  51 #elif HAVE_NETINET_IPL_H
  52 #include <netinet/ipl.h>
  53 #endif
  54 #if HAVE_IP_FIL_COMPAT_H
  55 #include <ip_fil_compat.h>
  56 #elif HAVE_NETINET_IP_FIL_COMPAT_H
  57 #include <netinet/ip_fil_compat.h>
  58 #elif HAVE_IP_COMPAT_H
  59 #include <ip_compat.h>
  60 #elif HAVE_NETINET_IP_COMPAT_H
  61 #include <netinet/ip_compat.h>
  62 #endif
  63 #if HAVE_IP_FIL_H
  64 #include <ip_fil.h>
  65 #elif HAVE_NETINET_IP_FIL_H
  66 #include <netinet/ip_fil.h>
  67 #endif
  68 #if HAVE_IP_NAT_H
  69 #include <ip_nat.h>
  70 #elif HAVE_NETINET_IP_NAT_H
  71 #include <netinet/ip_nat.h>
  72 #endif
  73 #if HAVE_ERRNO_H
  74 #include <errno.h>
  75 #endif
  76
  77 #endif /* IPF_TRANSPARENT required headers */
  78
  79 #if PF_TRANSPARENT
  80 #include <sys/socket.h>
  81 #include <sys/ioctl.h>
  82 #include <sys/fcntl.h>
  83 #include <net/if.h>
  84 #include <netinet/in.h>
  85 #if HAVE_NET_PF_PFVAR_H
  86 #include <net/pf/pfvar.h>
  87 #endif /* HAVE_NET_PF_PFVAR_H */
  88 #if HAVE_NET_PFVAR_H
  89 #include <net/pfvar.h>
  90 #endif /* HAVE_NET_PFVAR_H */
  91 #endif /* PF_TRANSPARENT required headers */
  92
  93 #if LINUX_NETFILTER
  94 #include <linux/netfilter_ipv4.h>
  95 #endif
  96
  97 // single global instance for access by other components.
  98 Ip::Intercept Ip::Interceptor;
  99
 100 void
 101 Ip::Intercept::StopTransparency(const char *str)
 102 {
 103     if (transparentActive_) {
 104         debugs(89, DBG_IMPORTANT, "Stopping full transparency: " << str);
 105         transparentActive_ = 0;
 106     }
 107 }
 108
 109 void
 110 Ip::Intercept::StopInterception(const char *str)
 111 {
 112     if (interceptActive_) {
 113         debugs(89, DBG_IMPORTANT, "Stopping IP interception: " << str);
 114         interceptActive_ = 0;
 115     }
 116 }
 117
 118 bool
 119 Ip::Intercept::NetfilterInterception(const Comm::ConnectionPointer &newConn, int silent)
 120 {
 121 #if LINUX_NETFILTER
 122     struct sockaddr_in lookup;
 123     socklen_t len = sizeof(struct sockaddr_in);
 124     newConn->local.GetSockAddr(lookup);
 125
 126     /** \par
 127      * Try NAT lookup for REDIRECT or DNAT targets. */
 128     if ( getsockopt(newConn->fd, IPPROTO_IP, SO_ORIGINAL_DST, &lookup, &len) != 0) {
 129         if (!silent) {
 130             debugs(89, DBG_IMPORTANT, HERE << " NF getsockopt(SO_ORIGINAL_DST) failed on " << newConn << ": " << xstrerror());
 131             lastReported_ = squid_curtime;
 132         }
 133         debugs(89, 9, HERE << "address: " << newConn);
 134         return false;
 135     } else {
 136         newConn->local = lookup;
 137         debugs(89, 5, HERE << "address NAT: " << newConn);
 138         return true;
 139     }
 140 #endif
 141     return false;
 142 }
 143
 144 bool
 145 Ip::Intercept::NetfilterTransparent(const Comm::ConnectionPointer &newConn, int silent)
 146 {
 147 #if LINUX_NETFILTER
 148     /* Trust the user configured properly. If not no harm done.
 149      * We will simply attempt a bind outgoing on our own IP.
 150      */
 151     newConn->remote.SetPort(0); // allow random outgoing port to prevent address clashes
 152     debugs(89, 5, HERE << "address TPROXY: " << newConn);
 153     return true;
 154 #else
 155     return false;
 156 #endif
 157 }
 158
 159 bool
 160 Ip::Intercept::IpfwInterception(const Comm::ConnectionPointer &newConn, int silent)
 161 {
 162 #if IPFW_TRANSPARENT
 163     struct sockaddr_storage lookup;
 164     socklen_t len = sizeof(struct sockaddr_storage);
 165     newConn->local.GetSockAddr(lookup, AF_INET);
 166
 167     /** \par
 168      * Try lookup for IPFW interception. */
 169     if ( getsockname(newConn->fd, (struct sockaddr*)&lookup, &len) != 0 ) {
 170         if ( !silent ) {
 171             debugs(89, DBG_IMPORTANT, HERE << " IPFW getsockname(...) failed: " << xstrerror());
 172             lastReported_ = squid_curtime;
 173         }
 174         debugs(89, 9, HERE << "address: " << newConn);
 175         return false;
 176     } else {
 177         newConn->local = lookup;
 178         debugs(89, 5, HERE << "address NAT: " << newConn);
 179         return true;
 180     }
 181 #endif
 182     return false;
 183 }
 184
 185 bool
 186 Ip::Intercept::IpfInterception(const Comm::ConnectionPointer &newConn, int silent)
 187 {
 188 #if IPF_TRANSPARENT  /* --enable-ipf-transparent */
 189
 190     struct natlookup natLookup;
 191     static int natfd = -1;
 192     int x;
 193
 194     // all fields must be set to 0
 195     memset(&natLookup, 0, sizeof(natLookup));
 196     // for NAT lookup set local and remote IP:port's
 197     natLookup.nl_inport = htons(newConn->local.GetPort());
 198     newConn->local.GetInAddr(natLookup.nl_inip);
 199     natLookup.nl_outport = htons(newConn->remote.GetPort());
 200     newConn->remote.GetInAddr(natLookup.nl_outip);
 201     // ... and the TCP flag
 202     natLookup.nl_flags = IPN_TCP;
 203
 204     if (natfd < 0) {
 205         int save_errno;
 206         enter_suid();
 207 #ifdef IPNAT_NAME
 208         natfd = open(IPNAT_NAME, O_RDONLY, 0);
 209 #else
 210         natfd = open(IPL_NAT, O_RDONLY, 0);
 211 #endif
 212         save_errno = errno;
 213         leave_suid();
 214         errno = save_errno;
 215     }
 216
 217     if (natfd < 0) {
 218         if (!silent) {
 219             debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT open failed: " << xstrerror());
 220             lastReported_ = squid_curtime;
 221             return false;
 222         }
 223     }
 224
 225 #if defined(IPFILTER_VERSION) && (IPFILTER_VERSION >= 4000027)
 226     struct ipfobj obj;
 227     memset(&obj, 0, sizeof(obj));
 228     obj.ipfo_rev = IPFILTER_VERSION;
 229     obj.ipfo_size = sizeof(natLookup);
 230     obj.ipfo_ptr = &natLookup;
 231     obj.ipfo_type = IPFOBJ_NATLOOKUP;
 232
 233     x = ioctl(natfd, SIOCGNATL, &obj);
 234 #else
 235     /*
 236     * IP-Filter changed the type for SIOCGNATL between
 237     * 3.3 and 3.4.  It also changed the cmd value for
 238     * SIOCGNATL, so at least we can detect it.  We could
 239     * put something in configure and use ifdefs here, but
 240     * this seems simpler.
 241     */
 242     static int siocgnatl_cmd = SIOCGNATL & 0xff;
 243     if (63 == siocgnatl_cmd) {
 244         struct natlookup *nlp = &natLookup;
 245         x = ioctl(natfd, SIOCGNATL, &nlp);
 246     } else {
 247         x = ioctl(natfd, SIOCGNATL, &natLookup);
 248     }
 249
 250 #endif
 251     if (x < 0) {
 252         if (errno != ESRCH) {
 253             if (!silent) {
 254                 debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT lookup failed: ioctl(SIOCGNATL) (v=" << IPFILTER_VERSION << "): " << xstrerror());
 255                 lastReported_ = squid_curtime;
 256             }
 257
 258             close(natfd);
 259             natfd = -1;
 260         }
 261
 262         debugs(89, 9, HERE << "address: " << newConn);
 263         return false;
 264     } else {
 265         newConn->local = natLookup.nl_realip;
 266         newConn->local.SetPort(ntohs(natLookup.nl_realport));
 267         debugs(89, 5, HERE << "address NAT: " << newConn);
 268         return true;
 269     }
 270
 271 #endif /* --enable-ipf-transparent */
 272     return false;
 273 }
 274
 275 bool
 276 Ip::Intercept::PfInterception(const Comm::ConnectionPointer &newConn, int silent)
 277 {
 278 #if PF_TRANSPARENT  /* --enable-pf-transparent */
 279
 280     struct pfioc_natlook nl;
 281     static int pffd = -1;
 282
 283     if (pffd < 0)
 284         pffd = open("/dev/pf", O_RDONLY);
 285
 286     if (pffd < 0) {
 287         if (!silent) {
 288             debugs(89, DBG_IMPORTANT, HERE << "PF open failed: " << xstrerror());
 289             lastReported_ = squid_curtime;
 290         }
 291         return false;
 292     }
 293
 294     memset(&nl, 0, sizeof(struct pfioc_natlook));
 295     newConn->remote.GetInAddr(nl.saddr.v4);
 296     nl.sport = htons(newConn->remote.GetPort());
 297
 298     newConn->local.GetInAddr(nl.daddr.v4);
 299     nl.dport = htons(newConn->local.GetPort());
 300
 301     nl.af = AF_INET;
 302     nl.proto = IPPROTO_TCP;
 303     nl.direction = PF_OUT;
 304
 305     if (ioctl(pffd, DIOCNATLOOK, &nl)) {
 306         if (errno != ENOENT) {
 307             if (!silent) {
 308                 debugs(89, DBG_IMPORTANT, HERE << "PF lookup failed: ioctl(DIOCNATLOOK)");
 309                 lastReported_ = squid_curtime;
 310             }
 311             close(pffd);
 312             pffd = -1;
 313         }
 314         debugs(89, 9, HERE << "address: " << newConn);
 315         return false;
 316     } else {
 317         newConn->local = nl.rdaddr.v4;
 318         newConn->local.SetPort(ntohs(nl.rdport));
 319         debugs(89, 5, HERE << "address NAT: " << newConn);
 320         return true;
 321     }
 322
 323 #endif /* --enable-pf-transparent */
 324     return false;
 325 }
 326
 327 bool
 328 Ip::Intercept::Lookup(const Comm::ConnectionPointer &newConn, const Comm::ConnectionPointer &listenConn)
 329 {
 330     /* --enable-linux-netfilter    */
 331     /* --enable-ipfw-transparent   */
 332     /* --enable-ipf-transparent    */
 333     /* --enable-pf-transparent     */
 334 #if IPF_TRANSPARENT || LINUX_NETFILTER || IPFW_TRANSPARENT || PF_TRANSPARENT
 335
 336 #if 0
 337     // Crop interception errors down to one per minute.
 338     int silent = (squid_curtime - lastReported_ > 60 ? 0 : 1);
 339 #else
 340     // Show all interception errors.
 341     int silent = 0;
 342 #endif
 343
 344     debugs(89, 5, HERE << "address BEGIN: me/client= " << newConn->local << ", destination/me= " << newConn->remote);
 345
 346     newConn->flags |= (listenConn->flags & (COMM_TRANSPARENT|COMM_INTERCEPTION));
 347
 348     /* NP: try TPROXY first, its much quieter than NAT when non-matching */
 349     if (transparentActive_ && listenConn->flags&COMM_TRANSPARENT) {
 350         if (NetfilterTransparent(newConn, silent)) return true;
 351     }
 352
 353     /* NAT is only available in IPv4 */
 354     if ( !newConn->local.IsIPv4()  ) return false;
 355     if ( !newConn->remote.IsIPv4() ) return false;
 356
 357     if (interceptActive_ && listenConn->flags&COMM_INTERCEPTION) {
 358         /* NAT methods that use sock-opts to return client address */
 359         if (NetfilterInterception(newConn, silent)) return true;
 360         if (IpfwInterception(newConn, silent)) return true;
 361
 362         /* NAT methods that use ioctl to return client address AND destination address */
 363         if (PfInterception(newConn, silent)) return true;
 364         if (IpfInterception(newConn, silent)) return true;
 365     }
 366
 367 #else /* none of the transparent options configured */
 368     debugs(89, DBG_IMPORTANT, "WARNING: transparent proxying not supported");
 369 #endif
 370
 371     return false;
 372 }
 373
 374 bool
 375 Ip::Intercept::ProbeForTproxy(Ip::Address &test)
 376 {
 377     debugs(3, 3, "Detect TPROXY support on port " << test);
 378
 379 #if defined(IP_TRANSPARENT)
 380
 381     int tos = 1;
 382     int tmp_sock = -1;
 383
 384     /* Probe to see if the Kernel TPROXY support is IPv6-enabled */
 385     if (test.IsIPv6()) {
 386         debugs(3, 3, "...Probing for IPv6 TPROXY support.");
 387
 388         struct sockaddr_in6 tmp_ip6;
 389         Ip::Address tmp = "::2";
 390         tmp.SetPort(0);
 391         tmp.GetSockAddr(tmp_ip6);
 392
 393         if ( (tmp_sock = socket(PF_INET6, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 394                 setsockopt(tmp_sock, SOL_IP, IP_TRANSPARENT, (char *)&tos, sizeof(int)) == 0 &&
 395                 bind(tmp_sock, (struct sockaddr*)&tmp_ip6, sizeof(struct sockaddr_in6)) == 0 ) {
 396
 397             debugs(3, 3, "IPv6 TPROXY support detected. Using.");
 398             close(tmp_sock);
 399             return true;
 400         }
 401         if (tmp_sock >= 0) {
 402             close(tmp_sock);
 403             tmp_sock = -1;
 404         }
 405     }
 406
 407     if ( test.IsIPv6() && !test.SetIPv4() ) {
 408         debugs(3, DBG_CRITICAL, "TPROXY lacks IPv6 support for " << test );
 409         return false;
 410     }
 411
 412     /* Probe to see if the Kernel TPROXY support is IPv4-enabled (aka present) */
 413     if (test.IsIPv4()) {
 414         debugs(3, 3, "...Probing for IPv4 TPROXY support.");
 415
 416         struct sockaddr_in tmp_ip4;
 417         Ip::Address tmp = "127.0.0.2";
 418         tmp.SetPort(0);
 419         tmp.GetSockAddr(tmp_ip4);
 420
 421         if ( (tmp_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 422                 setsockopt(tmp_sock, SOL_IP, IP_TRANSPARENT, (char *)&tos, sizeof(int)) == 0 &&
 423                 bind(tmp_sock, (struct sockaddr*)&tmp_ip4, sizeof(struct sockaddr_in)) == 0 ) {
 424
 425             debugs(3, 3, "IPv4 TPROXY support detected. Using.");
 426             close(tmp_sock);
 427             return true;
 428         }
 429         if (tmp_sock >= 0) {
 430             close(tmp_sock);
 431         }
 432     }
 433
 434 #else /* undefined IP_TRANSPARENT */
 435     debugs(3, 3, "setsockopt(IP_TRANSPARENT) not supported on this platform. Disabling TPROXYv4.");
 436 #endif
 437     return false;
 438 }