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