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 "fde.h"
  36 #include "ip/Intercept.h"
  37 #include "src/tools.h"
  38
  39 #if IPF_TRANSPARENT
  40
  41 #if HAVE_SYS_IOCTL_H
  42 #include <sys/ioctl.h>
  43 #endif
  44 #if HAVE_NETINET_TCP_H
  45 #include <netinet/tcp.h>
  46 #endif
  47 #if HAVE_NET_IF_H
  48 #include <net/if.h>
  49 #endif
  50 #if HAVE_IPL_H
  51 #include <ipl.h>
  52 #elif HAVE_NETINET_IPL_H
  53 #include <netinet/ipl.h>
  54 #endif
  55 #if HAVE_IP_FIL_COMPAT_H
  56 #include <ip_fil_compat.h>
  57 #elif HAVE_NETINET_IP_FIL_COMPAT_H
  58 #include <netinet/ip_fil_compat.h>
  59 #elif HAVE_IP_COMPAT_H
  60 #include <ip_compat.h>
  61 #elif HAVE_NETINET_IP_COMPAT_H
  62 #include <netinet/ip_compat.h>
  63 #endif
  64 #if HAVE_IP_FIL_H
  65 #include <ip_fil.h>
  66 #elif HAVE_NETINET_IP_FIL_H
  67 #include <netinet/ip_fil.h>
  68 #endif
  69 #if HAVE_IP_NAT_H
  70 #include <ip_nat.h>
  71 #elif HAVE_NETINET_IP_NAT_H
  72 #include <netinet/ip_nat.h>
  73 #endif
  74 #if HAVE_ERRNO_H
  75 #include <errno.h>
  76 #endif
  77
  78 #endif /* IPF_TRANSPARENT required headers */
  79
  80 #if PF_TRANSPARENT
  81 #include <sys/socket.h>
  82 #include <sys/ioctl.h>
  83 #include <sys/fcntl.h>
  84 #include <net/if.h>
  85 #include <netinet/in.h>
  86 #if HAVE_NET_PF_PFVAR_H
  87 #include <net/pf/pfvar.h>
  88 #endif /* HAVE_NET_PF_PFVAR_H */
  89 #if HAVE_NET_PFVAR_H
  90 #include <net/pfvar.h>
  91 #endif /* HAVE_NET_PFVAR_H */
  92 #endif /* PF_TRANSPARENT required headers */
  93
  94 #if LINUX_NETFILTER
  95 /* <climits> must be before including netfilter_ipv4.h */
  96 #include <climits>
  97 #include <linux/if.h>
  98 #include <linux/netfilter_ipv4.h>
  99 #if HAVE_LINUX_NETFILTER_IPV6_IP6_TABLES_H
 100 /* 2013-07-01: Pablo the Netfilter maintainer is rejecting patches
 101  * which will enable C++ compilers to build the Netfilter public headers.
 102  * We can auto-detect its presence and attempt to use in case he ever
 103  * changes his mind or things get cleaned up some other way.
 104  * But until then are usually forced to hard-code the getsockopt() code
 105  * for IPv6 NAT lookups.
 106  */
 107 #include <linux/netfilter_ipv6/ip6_tables.h>
 108 #endif
 109 #if !defined(IP6T_SO_ORIGINAL_DST)
 110 #define IP6T_SO_ORIGINAL_DST    80      // stolen with prejudice from the above file.
 111 #endif
 112 #endif /* LINUX_NETFILTER required headers */
 113
 114 // single global instance for access by other components.
 115 Ip::Intercept Ip::Interceptor;
 116
 117 void
 118 Ip::Intercept::StopTransparency(const char *str)
 119 {
 120     if (transparentActive_) {
 121         debugs(89, DBG_IMPORTANT, "Stopping full transparency: " << str);
 122         transparentActive_ = 0;
 123     }
 124 }
 125
 126 void
 127 Ip::Intercept::StopInterception(const char *str)
 128 {
 129     if (interceptActive_) {
 130         debugs(89, DBG_IMPORTANT, "Stopping IP interception: " << str);
 131         interceptActive_ = 0;
 132     }
 133 }
 134
 135 bool
 136 Ip::Intercept::NetfilterInterception(const Comm::ConnectionPointer &newConn, int silent)
 137 {
 138 #if LINUX_NETFILTER
 139     struct sockaddr_storage lookup;
 140     socklen_t len = newConn->local.isIPv6() ? sizeof(sockaddr_in6) : sizeof(sockaddr_in);
 141     newConn->local.getSockAddr(lookup, AF_UNSPEC);
 142
 143     /** \par
 144      * Try NAT lookup for REDIRECT or DNAT targets. */
 145     if ( getsockopt(newConn->fd,
 146                     newConn->local.isIPv6() ? IPPROTO_IPV6 : IPPROTO_IP,
 147                     newConn->local.isIPv6() ? IP6T_SO_ORIGINAL_DST : SO_ORIGINAL_DST,
 148                     &lookup,
 149                     &len) != 0) {
 150         if (!silent) {
 151             debugs(89, DBG_IMPORTANT, "ERROR: NF getsockopt(ORIGINAL_DST) failed on " << newConn << ": " << xstrerror());
 152             lastReported_ = squid_curtime;
 153         }
 154         debugs(89, 9, "address: " << newConn);
 155         return false;
 156     } else {
 157         newConn->local = lookup;
 158         debugs(89, 5, "address NAT: " << newConn);
 159         return true;
 160     }
 161 #endif
 162     return false;
 163 }
 164
 165 bool
 166 Ip::Intercept::TproxyTransparent(const Comm::ConnectionPointer &newConn, int silent)
 167 {
 168 #if (LINUX_NETFILTER && defined(IP_TRANSPARENT)) || \
 169     (PF_TRANSPARENT && defined(SO_BINDANY)) || \
 170     (IPFW_TRANSPARENT && defined(IP_BINDANY))
 171
 172     /* Trust the user configured properly. If not no harm done.
 173      * We will simply attempt a bind outgoing on our own IP.
 174      */
 175     newConn->remote.port(0); // allow random outgoing port to prevent address clashes
 176     debugs(89, 5, HERE << "address TPROXY: " << newConn);
 177     return true;
 178 #else
 179     return false;
 180 #endif
 181 }
 182
 183 bool
 184 Ip::Intercept::IpfwInterception(const Comm::ConnectionPointer &newConn, int silent)
 185 {
 186 #if IPFW_TRANSPARENT
 187     /* The getsockname() call performed already provided the TCP packet details.
 188      * There is no way to identify whether they came from NAT or not.
 189      * Trust the user configured properly.
 190      */
 191     debugs(89, 5, HERE << "address NAT: " << newConn);
 192     return true;
 193 #else
 194     return false;
 195 #endif
 196 }
 197
 198 bool
 199 Ip::Intercept::IpfInterception(const Comm::ConnectionPointer &newConn, int silent)
 200 {
 201 #if IPF_TRANSPARENT  /* --enable-ipf-transparent */
 202
 203     struct natlookup natLookup;
 204     static int natfd = -1;
 205     int x;
 206
 207     // all fields must be set to 0
 208     memset(&natLookup, 0, sizeof(natLookup));
 209     // for NAT lookup set local and remote IP:port's
 210     natLookup.nl_inport = htons(newConn->local.port());
 211     newConn->local.getInAddr(natLookup.nl_inip);
 212     natLookup.nl_outport = htons(newConn->remote.port());
 213     newConn->remote.getInAddr(natLookup.nl_outip);
 214     // ... and the TCP flag
 215     natLookup.nl_flags = IPN_TCP;
 216
 217     if (natfd < 0) {
 218         int save_errno;
 219         enter_suid();
 220 #ifdef IPNAT_NAME
 221         natfd = open(IPNAT_NAME, O_RDONLY, 0);
 222 #else
 223         natfd = open(IPL_NAT, O_RDONLY, 0);
 224 #endif
 225         save_errno = errno;
 226         leave_suid();
 227         errno = save_errno;
 228     }
 229
 230     if (natfd < 0) {
 231         if (!silent) {
 232             debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT open failed: " << xstrerror());
 233             lastReported_ = squid_curtime;
 234             return false;
 235         }
 236     }
 237
 238 #if defined(IPFILTER_VERSION) && (IPFILTER_VERSION >= 4000027)
 239     struct ipfobj obj;
 240     memset(&obj, 0, sizeof(obj));
 241     obj.ipfo_rev = IPFILTER_VERSION;
 242     obj.ipfo_size = sizeof(natLookup);
 243     obj.ipfo_ptr = &natLookup;
 244     obj.ipfo_type = IPFOBJ_NATLOOKUP;
 245
 246     x = ioctl(natfd, SIOCGNATL, &obj);
 247 #else
 248     /*
 249     * IP-Filter changed the type for SIOCGNATL between
 250     * 3.3 and 3.4.  It also changed the cmd value for
 251     * SIOCGNATL, so at least we can detect it.  We could
 252     * put something in configure and use ifdefs here, but
 253     * this seems simpler.
 254     */
 255     static int siocgnatl_cmd = SIOCGNATL & 0xff;
 256     if (63 == siocgnatl_cmd) {
 257         struct natlookup *nlp = &natLookup;
 258         x = ioctl(natfd, SIOCGNATL, &nlp);
 259     } else {
 260         x = ioctl(natfd, SIOCGNATL, &natLookup);
 261     }
 262
 263 #endif
 264     if (x < 0) {
 265         if (errno != ESRCH) {
 266             if (!silent) {
 267                 debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT lookup failed: ioctl(SIOCGNATL) (v=" << IPFILTER_VERSION << "): " << xstrerror());
 268                 lastReported_ = squid_curtime;
 269             }
 270
 271             close(natfd);
 272             natfd = -1;
 273         }
 274
 275         debugs(89, 9, HERE << "address: " << newConn);
 276         return false;
 277     } else {
 278         newConn->local = natLookup.nl_realip;
 279         newConn->local.port(ntohs(natLookup.nl_realport));
 280         debugs(89, 5, HERE << "address NAT: " << newConn);
 281         return true;
 282     }
 283
 284 #endif /* --enable-ipf-transparent */
 285     return false;
 286 }
 287
 288 bool
 289 Ip::Intercept::PfInterception(const Comm::ConnectionPointer &newConn, int silent)
 290 {
 291 #if PF_TRANSPARENT  /* --enable-pf-transparent */
 292
 293 #if !USE_NAT_DEVPF
 294     /* On recent PF versions the getsockname() call performed already provided
 295      * the required TCP packet details.
 296      * There is no way to identify whether they came from NAT or not.
 297      *
 298      * Trust the user configured properly.
 299      */
 300     debugs(89, 5, HERE << "address NAT divert-to: " << newConn);
 301     return true;
 302
 303 #else /* USE_NAT_DEVPF / --with-nat-devpf */
 304
 305     struct pfioc_natlook nl;
 306     static int pffd = -1;
 307
 308     if (pffd < 0)
 309         pffd = open("/dev/pf", O_RDONLY);
 310
 311     if (pffd < 0) {
 312         if (!silent) {
 313             debugs(89, DBG_IMPORTANT, HERE << "PF open failed: " << xstrerror());
 314             lastReported_ = squid_curtime;
 315         }
 316         return false;
 317     }
 318
 319     memset(&nl, 0, sizeof(struct pfioc_natlook));
 320     newConn->remote.getInAddr(nl.saddr.v4);
 321     nl.sport = htons(newConn->remote.port());
 322
 323     newConn->local.getInAddr(nl.daddr.v4);
 324     nl.dport = htons(newConn->local.port());
 325
 326     nl.af = AF_INET;
 327     nl.proto = IPPROTO_TCP;
 328     nl.direction = PF_OUT;
 329
 330     if (ioctl(pffd, DIOCNATLOOK, &nl)) {
 331         if (errno != ENOENT) {
 332             if (!silent) {
 333                 debugs(89, DBG_IMPORTANT, HERE << "PF lookup failed: ioctl(DIOCNATLOOK)");
 334                 lastReported_ = squid_curtime;
 335             }
 336             close(pffd);
 337             pffd = -1;
 338         }
 339         debugs(89, 9, HERE << "address: " << newConn);
 340         return false;
 341     } else {
 342         newConn->local = nl.rdaddr.v4;
 343         newConn->local.port(ntohs(nl.rdport));
 344         debugs(89, 5, HERE << "address NAT: " << newConn);
 345         return true;
 346     }
 347 #endif /* --with-nat-devpf */
 348 #endif /* --enable-pf-transparent */
 349     return false;
 350 }
 351
 352 bool
 353 Ip::Intercept::Lookup(const Comm::ConnectionPointer &newConn, const Comm::ConnectionPointer &listenConn)
 354 {
 355     /* --enable-linux-netfilter    */
 356     /* --enable-ipfw-transparent   */
 357     /* --enable-ipf-transparent    */
 358     /* --enable-pf-transparent     */
 359 #if IPF_TRANSPARENT || LINUX_NETFILTER || IPFW_TRANSPARENT || PF_TRANSPARENT
 360
 361 #if 0
 362     // Crop interception errors down to one per minute.
 363     int silent = (squid_curtime - lastReported_ > 60 ? 0 : 1);
 364 #else
 365     // Show all interception errors.
 366     int silent = 0;
 367 #endif
 368
 369     debugs(89, 5, HERE << "address BEGIN: me/client= " << newConn->local << ", destination/me= " << newConn->remote);
 370
 371     newConn->flags |= (listenConn->flags & (COMM_TRANSPARENT|COMM_INTERCEPTION));
 372
 373     /* NP: try TPROXY first, its much quieter than NAT when non-matching */
 374     if (transparentActive_ && listenConn->flags&COMM_TRANSPARENT) {
 375         if (TproxyTransparent(newConn, silent)) return true;
 376     }
 377
 378     if (interceptActive_ && listenConn->flags&COMM_INTERCEPTION) {
 379         /* NAT methods that use sock-opts to return client address */
 380         if (NetfilterInterception(newConn, silent)) return true;
 381         if (IpfwInterception(newConn, silent)) return true;
 382
 383         /* NAT methods that use ioctl to return client address AND destination address */
 384         if (PfInterception(newConn, silent)) return true;
 385         if (IpfInterception(newConn, silent)) return true;
 386     }
 387
 388 #else /* none of the transparent options configured */
 389     debugs(89, DBG_IMPORTANT, "WARNING: transparent proxying not supported");
 390 #endif
 391
 392     return false;
 393 }
 394
 395 bool
 396 Ip::Intercept::ProbeForTproxy(Ip::Address &test)
 397 {
 398     bool doneSuid = false;
 399
 400 #if _SQUID_LINUX_ && defined(IP_TRANSPARENT) // Linux
 401 # define soLevel SOL_IP
 402 # define soFlag  IP_TRANSPARENT
 403
 404 #elif defined(SO_BINDANY) // OpenBSD 4.7+ and NetBSD with PF
 405 # define soLevel SOL_SOCKET
 406 # define soFlag  SO_BINDANY
 407     enter_suid();
 408     doneSuid = true;
 409
 410 #elif defined(IP_BINDANY) // FreeBSD with IPFW
 411 # define soLevel IPPROTO_IP
 412 # define soFlag  IP_BINDANY
 413     enter_suid();
 414     doneSuid = true;
 415
 416 #endif
 417
 418 #if defined(soLevel) && defined(soFlag)
 419
 420     debugs(3, 3, "Detect TPROXY support on port " << test);
 421
 422     int tos = 1;
 423     int tmp_sock = -1;
 424
 425     /* Probe to see if the Kernel TPROXY support is IPv6-enabled */
 426     if (test.isIPv6()) {
 427         debugs(3, 3, "...Probing for IPv6 TPROXY support.");
 428
 429         struct sockaddr_in6 tmp_ip6;
 430         Ip::Address tmp = "::2";
 431         tmp.port(0);
 432         tmp.getSockAddr(tmp_ip6);
 433
 434         if ( (tmp_sock = socket(PF_INET6, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 435                 setsockopt(tmp_sock, soLevel, soFlag, (char *)&tos, sizeof(int)) == 0 &&
 436                 bind(tmp_sock, (struct sockaddr*)&tmp_ip6, sizeof(struct sockaddr_in6)) == 0 ) {
 437
 438             debugs(3, 3, "IPv6 TPROXY support detected. Using.");
 439             close(tmp_sock);
 440             if (doneSuid)
 441                 leave_suid();
 442             return true;
 443         }
 444         if (tmp_sock >= 0) {
 445             close(tmp_sock);
 446             tmp_sock = -1;
 447         }
 448     }
 449
 450     if ( test.isIPv6() && !test.setIPv4() ) {
 451         debugs(3, DBG_CRITICAL, "TPROXY lacks IPv6 support for " << test );
 452         if (doneSuid)
 453             leave_suid();
 454         return false;
 455     }
 456
 457     /* Probe to see if the Kernel TPROXY support is IPv4-enabled (aka present) */
 458     if (test.isIPv4()) {
 459         debugs(3, 3, "...Probing for IPv4 TPROXY support.");
 460
 461         struct sockaddr_in tmp_ip4;
 462         Ip::Address tmp = "127.0.0.2";
 463         tmp.port(0);
 464         tmp.getSockAddr(tmp_ip4);
 465
 466         if ( (tmp_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 467                 setsockopt(tmp_sock, soLevel, soFlag, (char *)&tos, sizeof(int)) == 0 &&
 468                 bind(tmp_sock, (struct sockaddr*)&tmp_ip4, sizeof(struct sockaddr_in)) == 0 ) {
 469
 470             debugs(3, 3, "IPv4 TPROXY support detected. Using.");
 471             close(tmp_sock);
 472             if (doneSuid)
 473                 leave_suid();
 474             return true;
 475         }
 476         if (tmp_sock >= 0) {
 477             close(tmp_sock);
 478         }
 479     }
 480
 481 #else
 482     debugs(3, 3, "TPROXY setsockopt() not supported on this platform. Disabling TPROXY.");
 483
 484 #endif
 485     if (doneSuid)
 486         leave_suid();
 487     return false;
 488 }