Intercept.cc
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1 /*
2  * Copyright (C) 1996-2018 The Squid Software Foundation and contributors
3  *
4  * Squid software is distributed under GPLv2+ license and includes
5  * contributions from numerous individuals and organizations.
6  * Please see the COPYING and CONTRIBUTORS files for details.
7  */
8 
9 /* DEBUG: section 89 NAT / IP Interception */
10 
11 // Enable hack to workaround Solaris 10 IPFilter breakage
12 #define BUILDING_SQUID_IP_INTERCEPT_CC 1
13 
14 #include "squid.h"
15 #include "comm/Connection.h"
16 #include "fde.h"
17 #include "ip/Intercept.h"
18 #include "src/tools.h"
19 
20 #include <cerrno>
21 
22 #if IPF_TRANSPARENT
23 
24 #if !defined(IPFILTER_VERSION)
25 #define IPFILTER_VERSION 5000004
26 #endif
27 
28 #if HAVE_SYS_PARAM_H
29 #include <sys/param.h>
30 #endif
31 #if HAVE_SYS_IOCCOM_H
32 #include <sys/ioccom.h>
33 #endif
34 #if HAVE_SYS_IOCTL_H
35 #include <sys/ioctl.h>
36 #endif
37 #if HAVE_NETINET_IP6_H
38 #include <netinet/ip6.h>
39 #endif
40 #if HAVE_NETINET_TCP_H
41 #include <netinet/tcp.h>
42 #endif
43 #if HAVE_NET_IF_H
44 #include <net/if.h>
45 #endif
46 #if HAVE_IPL_H
47 #include <ipl.h>
48 #elif HAVE_NETINET_IPL_H
49 #include <netinet/ipl.h>
50 #endif
51 #if USE_SOLARIS_IPFILTER_MINOR_T_HACK
52 #undef minor_t
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 
74 #endif /* IPF_TRANSPARENT required headers */
75 
76 #if PF_TRANSPARENT
77 #include <sys/socket.h>
78 #include <sys/ioctl.h>
79 #include <sys/fcntl.h>
80 #include <net/if.h>
81 #include <netinet/in.h>
82 #if HAVE_NET_PF_PFVAR_H
83 #include <net/pf/pfvar.h>
84 #endif /* HAVE_NET_PF_PFVAR_H */
85 #if HAVE_NET_PFVAR_H
86 #include <net/pfvar.h>
87 #endif /* HAVE_NET_PFVAR_H */
88 #endif /* PF_TRANSPARENT required headers */
89 
90 #if LINUX_NETFILTER
91 /* <climits> must be before including netfilter_ipv4.h */
92 #include <climits>
93 #include <linux/if.h>
94 #include <linux/netfilter_ipv4.h>
95 #if HAVE_LINUX_NETFILTER_IPV6_IP6_TABLES_H
96 /* 2013-07-01: Pablo the Netfilter maintainer is rejecting patches
97  * which will enable C++ compilers to build the Netfilter public headers.
98  * We can auto-detect its presence and attempt to use in case he ever
99  * changes his mind or things get cleaned up some other way.
100  * But until then are usually forced to hard-code the getsockopt() code
101  * for IPv6 NAT lookups.
102  */
103 #include <linux/netfilter_ipv6/ip6_tables.h>
104 #endif
105 #if !defined(IP6T_SO_ORIGINAL_DST)
106 #define IP6T_SO_ORIGINAL_DST 80 // stolen with prejudice from the above file.
107 #endif
108 #endif /* LINUX_NETFILTER required headers */
109 
110 // single global instance for access by other components.
112 
113 void
115 {
116  if (transparentActive_) {
117  debugs(89, DBG_IMPORTANT, "Stopping full transparency: " << str);
118  transparentActive_ = 0;
119  }
120 }
121 
122 void
124 {
125  if (interceptActive_) {
126  debugs(89, DBG_IMPORTANT, "Stopping IP interception: " << str);
127  interceptActive_ = 0;
128  }
129 }
130 
131 bool
133 {
134 #if LINUX_NETFILTER
135  struct sockaddr_storage lookup;
136  socklen_t len = newConn->local.isIPv6() ? sizeof(sockaddr_in6) : sizeof(sockaddr_in);
137  newConn->local.getSockAddr(lookup, AF_UNSPEC);
138 
141  if ( getsockopt(newConn->fd,
142  newConn->local.isIPv6() ? IPPROTO_IPV6 : IPPROTO_IP,
143  newConn->local.isIPv6() ? IP6T_SO_ORIGINAL_DST : SO_ORIGINAL_DST,
144  &lookup,
145  &len) != 0) {
146  if (!silent) {
147  int xerrno = errno;
148  debugs(89, DBG_IMPORTANT, "ERROR: NF getsockopt(ORIGINAL_DST) failed on " << newConn << ": " << xstrerr(xerrno));
149  lastReported_ = squid_curtime;
150  }
151  debugs(89, 9, "address: " << newConn);
152  return false;
153  } else {
154  newConn->local = lookup;
155  debugs(89, 5, "address NAT: " << newConn);
156  return true;
157  }
158 #endif
159  return false;
160 }
161 
162 bool
164 {
165 #if (LINUX_NETFILTER && defined(IP_TRANSPARENT)) || \
166  (PF_TRANSPARENT && defined(SO_BINDANY)) || \
167  (IPFW_TRANSPARENT && defined(IP_BINDANY))
168 
169  /* Trust the user configured properly. If not no harm done.
170  * We will simply attempt a bind outgoing on our own IP.
171  */
172  debugs(89, 5, HERE << "address TPROXY: " << newConn);
173  return true;
174 #else
175  return false;
176 #endif
177 }
178 
179 bool
181 {
182 #if IPFW_TRANSPARENT
183  /* The getsockname() call performed already provided the TCP packet details.
184  * There is no way to identify whether they came from NAT or not.
185  * Trust the user configured properly.
186  */
187  debugs(89, 5, HERE << "address NAT: " << newConn);
188  return true;
189 #else
190  return false;
191 #endif
192 }
193 
194 bool
196 {
197 #if IPF_TRANSPARENT /* --enable-ipf-transparent */
198 
199  struct natlookup natLookup;
200  static int natfd = -1;
201  int x;
202 
203  // all fields must be set to 0
204  memset(&natLookup, 0, sizeof(natLookup));
205  // for NAT lookup set local and remote IP:port's
206  if (newConn->remote.isIPv6()) {
207 #if HAVE_NATLOOKUP_NL_INIPADDR_IN6
208  natLookup.nl_v = 6;
209  newConn->local.getInAddr(natLookup.nl_inipaddr.in6);
210  newConn->remote.getInAddr(natLookup.nl_outipaddr.in6);
211  }
212  else {
213  natLookup.nl_v = 4;
214  newConn->local.getInAddr(natLookup.nl_inipaddr.in4);
215  newConn->remote.getInAddr(natLookup.nl_outipaddr.in4);
216  }
217 #else
218  // warn once every 10 at critical level, then push down a level each repeated event
219  static int warningLevel = DBG_CRITICAL;
220  debugs(89, warningLevel, "Your IPF (IPFilter) NAT does not support IPv6. Please upgrade it.");
221  warningLevel = (warningLevel + 1) % 10;
222  return false;
223  }
224  newConn->local.getInAddr(natLookup.nl_inip);
225  newConn->remote.getInAddr(natLookup.nl_outip);
226 #endif
227  natLookup.nl_inport = htons(newConn->local.port());
228  natLookup.nl_outport = htons(newConn->remote.port());
229  // ... and the TCP flag
230  natLookup.nl_flags = IPN_TCP;
231 
232  if (natfd < 0) {
233  int save_errno;
234  enter_suid();
235 #ifdef IPNAT_NAME
236  natfd = open(IPNAT_NAME, O_RDONLY, 0);
237 #else
238  natfd = open(IPL_NAT, O_RDONLY, 0);
239 #endif
240  save_errno = errno;
241  leave_suid();
242  errno = save_errno;
243  }
244 
245  if (natfd < 0) {
246  if (!silent) {
247  int xerrno = errno;
248  debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT open failed: " << xstrerr(xerrno));
249  lastReported_ = squid_curtime;
250  return false;
251  }
252  }
253 
254 #if defined(IPFILTER_VERSION) && (IPFILTER_VERSION >= 4000027)
255  struct ipfobj obj;
256  memset(&obj, 0, sizeof(obj));
257  obj.ipfo_rev = IPFILTER_VERSION;
258  obj.ipfo_size = sizeof(natLookup);
259  obj.ipfo_ptr = &natLookup;
260  obj.ipfo_type = IPFOBJ_NATLOOKUP;
261 
262  x = ioctl(natfd, SIOCGNATL, &obj);
263 #else
264  /*
265  * IP-Filter changed the type for SIOCGNATL between
266  * 3.3 and 3.4. It also changed the cmd value for
267  * SIOCGNATL, so at least we can detect it. We could
268  * put something in configure and use ifdefs here, but
269  * this seems simpler.
270  */
271  static int siocgnatl_cmd = SIOCGNATL & 0xff;
272  if (63 == siocgnatl_cmd) {
273  struct natlookup *nlp = &natLookup;
274  x = ioctl(natfd, SIOCGNATL, &nlp);
275  } else {
276  x = ioctl(natfd, SIOCGNATL, &natLookup);
277  }
278 
279 #endif
280  if (x < 0) {
281  int xerrno = errno;
282  if (xerrno != ESRCH) {
283  if (!silent) {
284  debugs(89, DBG_IMPORTANT, "IPF (IPFilter) NAT lookup failed: ioctl(SIOCGNATL) (v=" << IPFILTER_VERSION << "): " << xstrerr(xerrno));
285  lastReported_ = squid_curtime;
286  }
287 
288  close(natfd);
289  natfd = -1;
290  }
291 
292  debugs(89, 9, HERE << "address: " << newConn);
293  return false;
294  } else {
295 #if HAVE_NATLOOKUP_NL_REALIPADDR_IN6
296  if (newConn->remote.isIPv6())
297  newConn->local = natLookup.nl_realipaddr.in6;
298  else
299  newConn->local = natLookup.nl_realipaddr.in4;
300 #else
301  newConn->local = natLookup.nl_realip;
302 #endif
303  newConn->local.port(ntohs(natLookup.nl_realport));
304  debugs(89, 5, HERE << "address NAT: " << newConn);
305  return true;
306  }
307 
308 #endif /* --enable-ipf-transparent */
309  return false;
310 }
311 
312 bool
314 {
315 #if PF_TRANSPARENT /* --enable-pf-transparent */
316 
317 #if !USE_NAT_DEVPF
318  /* On recent PF versions the getsockname() call performed already provided
319  * the required TCP packet details.
320  * There is no way to identify whether they came from NAT or not.
321  *
322  * Trust the user configured properly.
323  */
324  debugs(89, 5, HERE << "address NAT divert-to: " << newConn);
325  return true;
326 
327 #else /* USE_NAT_DEVPF / --with-nat-devpf */
328 
329  struct pfioc_natlook nl;
330  static int pffd = -1;
331 
332  if (pffd < 0)
333  pffd = open("/dev/pf", O_RDONLY);
334 
335  if (pffd < 0) {
336  if (!silent) {
337  int xerrno = errno;
338  debugs(89, DBG_IMPORTANT, MYNAME << "PF open failed: " << xstrerr(xerrno));
339  lastReported_ = squid_curtime;
340  }
341  return false;
342  }
343 
344  memset(&nl, 0, sizeof(struct pfioc_natlook));
345 
346  if (newConn->remote.isIPv6()) {
347  newConn->remote.getInAddr(nl.saddr.v6);
348  newConn->local.getInAddr(nl.daddr.v6);
349  nl.af = AF_INET6;
350  } else {
351  newConn->remote.getInAddr(nl.saddr.v4);
352  newConn->local.getInAddr(nl.daddr.v4);
353  nl.af = AF_INET;
354  }
355 
356  nl.sport = htons(newConn->remote.port());
357  nl.dport = htons(newConn->local.port());
358 
359  nl.proto = IPPROTO_TCP;
360  nl.direction = PF_OUT;
361 
362  if (ioctl(pffd, DIOCNATLOOK, &nl)) {
363  int xerrno = errno;
364  if (xerrno != ENOENT) {
365  if (!silent) {
366  debugs(89, DBG_IMPORTANT, HERE << "PF lookup failed: ioctl(DIOCNATLOOK): " << xstrerr(xerrno));
367  lastReported_ = squid_curtime;
368  }
369  close(pffd);
370  pffd = -1;
371  }
372  debugs(89, 9, HERE << "address: " << newConn);
373  return false;
374  } else {
375  if (newConn->remote.isIPv6())
376  newConn->local = nl.rdaddr.v6;
377  else
378  newConn->local = nl.rdaddr.v4;
379  newConn->local.port(ntohs(nl.rdport));
380  debugs(89, 5, HERE << "address NAT: " << newConn);
381  return true;
382  }
383 #endif /* --with-nat-devpf */
384 #endif /* --enable-pf-transparent */
385  return false;
386 }
387 
388 bool
390 {
391  /* --enable-linux-netfilter */
392  /* --enable-ipfw-transparent */
393  /* --enable-ipf-transparent */
394  /* --enable-pf-transparent */
395 #if IPF_TRANSPARENT || LINUX_NETFILTER || IPFW_TRANSPARENT || PF_TRANSPARENT
396 
397 #if 0
398  // Crop interception errors down to one per minute.
399  int silent = (squid_curtime - lastReported_ > 60 ? 0 : 1);
400 #else
401  // Show all interception errors.
402  int silent = 0;
403 #endif
404 
405  debugs(89, 5, HERE << "address BEGIN: me/client= " << newConn->local << ", destination/me= " << newConn->remote);
406 
407  newConn->flags |= (listenConn->flags & (COMM_TRANSPARENT|COMM_INTERCEPTION));
408 
409  /* NP: try TPROXY first, its much quieter than NAT when non-matching */
410  if (transparentActive_ && listenConn->flags&COMM_TRANSPARENT) {
411  if (TproxyTransparent(newConn, silent)) return true;
412  }
413 
414  if (interceptActive_ && listenConn->flags&COMM_INTERCEPTION) {
415  /* NAT methods that use sock-opts to return client address */
416  if (NetfilterInterception(newConn, silent)) return true;
417  if (IpfwInterception(newConn, silent)) return true;
418 
419  /* NAT methods that use ioctl to return client address AND destination address */
420  if (PfInterception(newConn, silent)) return true;
421  if (IpfInterception(newConn, silent)) return true;
422  }
423 
424 #else /* none of the transparent options configured */
425  debugs(89, DBG_IMPORTANT, "WARNING: transparent proxying not supported");
426 #endif
427 
428  return false;
429 }
430 
431 bool
433 {
434  bool doneSuid = false;
435 
436 #if _SQUID_LINUX_ && defined(IP_TRANSPARENT) // Linux
437 # define soLevel SOL_IP
438 # define soFlag IP_TRANSPARENT
439 
440 #elif defined(SO_BINDANY) // OpenBSD 4.7+ and NetBSD with PF
441 # define soLevel SOL_SOCKET
442 # define soFlag SO_BINDANY
443  enter_suid();
444  doneSuid = true;
445 
446 #elif defined(IP_BINDANY) // FreeBSD with IPFW
447 # define soLevel IPPROTO_IP
448 # define soFlag IP_BINDANY
449  enter_suid();
450  doneSuid = true;
451 
452 #endif
453 
454 #if defined(soLevel) && defined(soFlag)
455 
456  debugs(3, 3, "Detect TPROXY support on port " << test);
457 
458  int tos = 1;
459  int tmp_sock = -1;
460 
461  /* Probe to see if the Kernel TPROXY support is IPv6-enabled */
462  if (test.isIPv6()) {
463  debugs(3, 3, "...Probing for IPv6 TPROXY support.");
464 
465  struct sockaddr_in6 tmp_ip6;
466  Ip::Address tmp = "::2";
467  tmp.port(0);
468  tmp.getSockAddr(tmp_ip6);
469 
470  if ( (tmp_sock = socket(PF_INET6, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
471  setsockopt(tmp_sock, soLevel, soFlag, (char *)&tos, sizeof(int)) == 0 &&
472  bind(tmp_sock, (struct sockaddr*)&tmp_ip6, sizeof(struct sockaddr_in6)) == 0 ) {
473 
474  debugs(3, 3, "IPv6 TPROXY support detected. Using.");
475  close(tmp_sock);
476  if (doneSuid)
477  leave_suid();
478  return true;
479  }
480  if (tmp_sock >= 0) {
481  close(tmp_sock);
482  tmp_sock = -1;
483  }
484  }
485 
486  if ( test.isIPv6() && !test.setIPv4() ) {
487  debugs(3, DBG_CRITICAL, "TPROXY lacks IPv6 support for " << test );
488  if (doneSuid)
489  leave_suid();
490  return false;
491  }
492 
493  /* Probe to see if the Kernel TPROXY support is IPv4-enabled (aka present) */
494  if (test.isIPv4()) {
495  debugs(3, 3, "...Probing for IPv4 TPROXY support.");
496 
497  struct sockaddr_in tmp_ip4;
498  Ip::Address tmp = "127.0.0.2";
499  tmp.port(0);
500  tmp.getSockAddr(tmp_ip4);
501 
502  if ( (tmp_sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
503  setsockopt(tmp_sock, soLevel, soFlag, (char *)&tos, sizeof(int)) == 0 &&
504  bind(tmp_sock, (struct sockaddr*)&tmp_ip4, sizeof(struct sockaddr_in)) == 0 ) {
505 
506  debugs(3, 3, "IPv4 TPROXY support detected. Using.");
507  close(tmp_sock);
508  if (doneSuid)
509  leave_suid();
510  return true;
511  }
512  if (tmp_sock >= 0) {
513  close(tmp_sock);
514  }
515  }
516 
517 #else
518  debugs(3, 3, "TPROXY setsockopt() not supported on this platform. Disabling TPROXY.");
519 
520 #endif
521  if (doneSuid)
522  leave_suid();
523  return false;
524 }
525 
bool setIPv4()
Definition: Address.cc:217
bool Lookup(const Comm::ConnectionPointer &newConn, const Comm::ConnectionPointer &listenConn)
Definition: Intercept.cc:389
int socklen_t
Definition: types.h:158
bool ProbeForTproxy(Address &test)
Definition: Intercept.cc:432
bool IpfwInterception(const Comm::ConnectionPointer &newConn, int silent)
Definition: Intercept.cc:180
#define COMM_INTERCEPTION
Definition: Connection.h:49
#define DBG_CRITICAL
Definition: Debug.h:45
bool PfInterception(const Comm::ConnectionPointer &newConn, int silent)
Definition: Intercept.cc:313
time_t squid_curtime
Definition: stub_time.cc:17
bool isIPv6() const
Definition: Address.cc:157
const char * xstrerr(int error)
Definition: xstrerror.cc:83
#define debugs(SECTION, LEVEL, CONTENT)
Definition: Debug.h:124
#define DBG_IMPORTANT
Definition: Debug.h:46
bool TproxyTransparent(const Comm::ConnectionPointer &newConn, int silent)
Definition: Intercept.cc:163
void leave_suid(void)
Definition: tools.cc:504
bool NetfilterInterception(const Comm::ConnectionPointer &newConn, int silent)
Definition: Intercept.cc:132
bool isIPv4() const
Definition: Address.cc:151
int unsigned int const char *desc STUB void int len
Definition: stub_fd.cc:20
void StopInterception(const char *str)
Definition: Intercept.cc:123
std::ostream & HERE(std::ostream &s)
Definition: Debug.h:153
void getSockAddr(struct sockaddr_storage &addr, const int family) const
Definition: Address.cc:927
unsigned short port() const
Definition: Address.cc:771
Ip::Address local
Definition: Connection.h:135
#define MYNAME
Definition: Debug.h:166
Ip::Address remote
Definition: Connection.h:138
#define COMM_TRANSPARENT
Definition: Connection.h:48
int transparentActive_
Definition: Intercept.h:140
void enter_suid(void)
Definition: tools.cc:575
void StopTransparency(const char *str)
Definition: Intercept.cc:114
bool IpfInterception(const Comm::ConnectionPointer &newConn, int silent)
Definition: Intercept.cc:195
bool getInAddr(struct in_addr &) const
Definition: Address.cc:1023
#define IP6T_SO_ORIGINAL_DST
Definition: Intercept.cc:106
Intercept Interceptor
Definition: Intercept.h:154

 

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