summaryrefslogtreecommitdiffstats
path: root/methods/aptmethod.h
blob: 1c24f3a9876d6220ad97a5357c8d889f6e11239a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
#ifndef APT_APTMETHOD_H
#define APT_APTMETHOD_H

#include "config.h"

#include <apt-pkg/acquire-method.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/error.h>
#include <apt-pkg/fileutl.h>
#include <apt-pkg/netrc.h>
#include <apt-pkg/strutl.h>

#include <algorithm>
#include <locale>
#include <memory>
#include <string>
#include <vector>

#include <cstdlib>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <apti18n.h>

#ifdef HAVE_SECCOMP
#include <csignal>

#include <seccomp.h>
#endif

enum class ResultState
{
   TRANSIENT_ERROR,
   FATAL_ERROR,
   SUCCESSFUL
};

static bool hasDoubleColon(std::string const &n)
{
   return n.find("::") != std::string::npos;
}

class aptConfigWrapperForMethods
{
protected:
   std::vector<std::string> methodNames;
public:
   void setPostfixForMethodNames(char const * const postfix) APT_NONNULL(2)
   {
      methodNames.erase(std::remove_if(methodNames.begin(), methodNames.end(), hasDoubleColon), methodNames.end());
      decltype(methodNames) toAdd;
      for (auto && name: methodNames)
	 toAdd.emplace_back(name + "::" + postfix);
      std::move(toAdd.begin(), toAdd.end(), std::back_inserter(methodNames));
   }

   bool DebugEnabled() const
   {
      if (methodNames.empty())
	 return false;
      auto const sni = std::find_if_not(methodNames.crbegin(), methodNames.crend(), hasDoubleColon);
      if (unlikely(sni == methodNames.crend()))
	 return false;
      auto const ln = methodNames[methodNames.size() - 1];
      // worst case: all three are the same
      std::string confln, confsn, confpn;
      strprintf(confln, "Debug::Acquire::%s", ln.c_str());
      strprintf(confsn, "Debug::Acquire::%s", sni->c_str());
      auto const pni = sni->substr(0, sni->find('+'));
      strprintf(confpn, "Debug::Acquire::%s", pni.c_str());
      return _config->FindB(confln,_config->FindB(confsn, _config->FindB(confpn, false)));
   }
   std::string ConfigFind(char const * const postfix, std::string const &defValue) const APT_NONNULL(2)
   {
      for (auto name = methodNames.rbegin(); name != methodNames.rend(); ++name)
      {
	 std::string conf;
	 strprintf(conf, "Acquire::%s::%s", name->c_str(), postfix);
	 auto value = _config->Find(conf);
	 if (not value.empty())
	    return value;
      }
      return defValue;
   }
   std::string ConfigFind(std::string const &postfix, std::string const &defValue) const
   {
      return ConfigFind(postfix.c_str(), defValue);
   }
   bool ConfigFindB(char const * const postfix, bool const defValue) const APT_NONNULL(2)
   {
      return StringToBool(ConfigFind(postfix, defValue ? "yes" : "no"), defValue);
   }
   int ConfigFindI(char const * const postfix, int const defValue) const APT_NONNULL(2)
   {
      char *End;
      std::string const value = ConfigFind(postfix, "");
      auto const Res = strtol(value.c_str(), &End, 0);
      if (value.c_str() == End)
	 return defValue;
      return Res;
   }

   explicit aptConfigWrapperForMethods(std::string const &name) : methodNames{{name}} {}
   explicit aptConfigWrapperForMethods(std::vector<std::string> &&names) : methodNames{std::move(names)} {}
};

class aptMethod : public pkgAcqMethod, public aptConfigWrapperForMethods
{
protected:
   std::string const Binary;
   unsigned long SeccompFlags;
   enum Seccomp
   {
      BASE = (1 << 1),
      NETWORK = (1 << 2),
      DIRECTORY = (1 << 3),
   };

   public:
   virtual bool Configuration(std::string Message) APT_OVERRIDE
   {
      if (pkgAcqMethod::Configuration(Message) == false)
	 return false;

      std::string const conf = std::string("Binary::") + Binary;
      _config->MoveSubTree(conf.c_str(), NULL);

      DropPrivsOrDie();
      if (LoadSeccomp() == false)
	 return false;

      return true;
   }

   bool RunningInQemu(void)
   {
      int status;
      pid_t pid;

      pid = fork();
      if (pid == 0)
      {
	 close(0);
	 close(1);
	 close(2);
	 setenv("QEMU_VERSION", "meow", 1);
	 char path[] = LIBEXEC_DIR "/apt-helper";
	 char *const argv[] = {path, NULL};
	 execv(argv[0], argv);
	 _exit(255);
      }

      // apt-helper is supposed to exit with an error. If it exited with 0,
      // qemu-user had problems with QEMU_VERSION and returned 0 => running in
      // qemu-user.

      if (waitpid(pid, &status, 0) == pid && WIFEXITED(status) && WEXITSTATUS(status) == 0)
	 return true;

      return false;
   }

   bool LoadSeccomp()
   {
#ifdef HAVE_SECCOMP
      int rc;
      scmp_filter_ctx ctx = NULL;

      if (SeccompFlags == 0)
	 return true;

      if (_config->FindB("APT::Sandbox::Seccomp", false) == false)
	 return true;

      if (RunningInQemu() == true)
      {
	 Warning("Running in qemu-user, not using seccomp");
	 return true;
      }

      ctx = seccomp_init(SCMP_ACT_TRAP);
      if (ctx == NULL)
	 return _error->FatalE("HttpMethod::Configuration", "Cannot init seccomp");

#define ALLOW(what)                                                     \
   if ((rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, SCMP_SYS(what), 0))) \
      return _error->FatalE("HttpMethod::Configuration", "Cannot allow %s: %s", #what, strerror(-rc));

      for (auto &custom : _config->FindVector("APT::Sandbox::Seccomp::Trap"))
      {
	 if ((rc = seccomp_rule_add(ctx, SCMP_ACT_TRAP, seccomp_syscall_resolve_name(custom.c_str()), 0)))
	    return _error->FatalE("HttpMethod::Configuration", "Cannot trap %s: %s", custom.c_str(), strerror(-rc));
      }

      ALLOW(access);
      ALLOW(arch_prctl);
      ALLOW(brk);
      ALLOW(chmod);
      ALLOW(chown);
      ALLOW(chown32);
      ALLOW(clock_getres);
      ALLOW(clock_getres_time64);
      ALLOW(clock_gettime);
      ALLOW(clock_gettime64);
      ALLOW(clock_nanosleep);
      ALLOW(clock_nanosleep_time64);
      ALLOW(close);
      ALLOW(creat);
      ALLOW(dup);
      ALLOW(dup2);
      ALLOW(dup3);
      ALLOW(exit);
      ALLOW(exit_group);
      ALLOW(faccessat);
      ALLOW(fchmod);
      ALLOW(fchmodat);
      ALLOW(fchown);
      ALLOW(fchown32);
      ALLOW(fchownat);
      ALLOW(fcntl);
      ALLOW(fcntl64);
      ALLOW(fdatasync);
      ALLOW(flock);
      ALLOW(fstat);
      ALLOW(fstat64);
      ALLOW(fstatat64);
      ALLOW(fstatfs);
      ALLOW(fstatfs64);
      ALLOW(fsync);
      ALLOW(ftime);
      ALLOW(ftruncate);
      ALLOW(ftruncate64);
      ALLOW(futex);
      ALLOW(futex_time64);
      ALLOW(futimesat);
      ALLOW(getegid);
      ALLOW(getegid32);
      ALLOW(geteuid);
      ALLOW(geteuid32);
      ALLOW(getgid);
      ALLOW(getgid32);
      ALLOW(getgroups);
      ALLOW(getgroups32);
      ALLOW(getpeername);
      ALLOW(getpgid);
      ALLOW(getpgrp);
      ALLOW(getpid);
      ALLOW(getppid);
      ALLOW(getrandom);
      ALLOW(getresgid);
      ALLOW(getresgid32);
      ALLOW(getresuid);
      ALLOW(getresuid32);
      ALLOW(getrlimit);
      ALLOW(get_robust_list);
      ALLOW(getrusage);
      ALLOW(gettid);
      ALLOW(gettimeofday);
      ALLOW(getuid);
      ALLOW(getuid32);
      ALLOW(ioctl);
      ALLOW(lchown);
      ALLOW(lchown32);
      ALLOW(_llseek);
      ALLOW(lseek);
      ALLOW(lstat);
      ALLOW(lstat64);
      ALLOW(madvise);
      ALLOW(mmap);
      ALLOW(mmap2);
      ALLOW(mprotect);
      ALLOW(mremap);
      ALLOW(msync);
      ALLOW(munmap);
      ALLOW(nanosleep);
      ALLOW(newfstatat);
      ALLOW(_newselect);
      ALLOW(oldfstat);
      ALLOW(oldlstat);
      ALLOW(oldolduname);
      ALLOW(oldstat);
      ALLOW(olduname);
      ALLOW(open);
      ALLOW(openat);
      ALLOW(pipe);
      ALLOW(pipe2);
      ALLOW(poll);
      ALLOW(ppoll);
      ALLOW(ppoll_time64);
      ALLOW(prctl);
      ALLOW(prlimit64);
      ALLOW(pselect6);
      ALLOW(pselect6_time64);
      ALLOW(read);
      ALLOW(readv);
      ALLOW(rename);
      ALLOW(renameat);
      ALLOW(renameat2);
      ALLOW(restart_syscall);
      ALLOW(rt_sigaction);
      ALLOW(rt_sigpending);
      ALLOW(rt_sigprocmask);
      ALLOW(rt_sigqueueinfo);
      ALLOW(rt_sigreturn);
      ALLOW(rt_sigsuspend);
      ALLOW(rt_sigtimedwait);
      ALLOW(sched_yield);
      ALLOW(select);
      ALLOW(set_robust_list);
      ALLOW(sigaction);
      ALLOW(sigpending);
      ALLOW(sigprocmask);
      ALLOW(sigreturn);
      ALLOW(sigsuspend);
      ALLOW(stat);
      ALLOW(stat64);
      ALLOW(statfs);
      ALLOW(statfs64);
#ifdef __NR_statx
      ALLOW(statx);
#endif
      ALLOW(sync);
      ALLOW(syscall);
      ALLOW(sysinfo);
      ALLOW(time);
      ALLOW(truncate);
      ALLOW(truncate64);
      ALLOW(ugetrlimit);
      ALLOW(umask);
      ALLOW(uname);
      ALLOW(unlink);
      ALLOW(unlinkat);
      ALLOW(utime);
      ALLOW(utimensat);
      ALLOW(utimensat_time64);
      ALLOW(utimes);
      ALLOW(write);
      ALLOW(writev);

      if ((SeccompFlags & Seccomp::NETWORK) != 0)
      {
	 ALLOW(bind);
	 ALLOW(connect);
	 ALLOW(getsockname);
	 ALLOW(getsockopt);
	 ALLOW(recv);
	 ALLOW(recvfrom);
	 ALLOW(recvmmsg);
	 ALLOW(recvmmsg_time64);
	 ALLOW(recvmsg);
	 ALLOW(send);
	 ALLOW(sendmmsg);
	 ALLOW(sendmsg);
	 ALLOW(sendto);
	 ALLOW(setsockopt);
	 ALLOW(shutdown);
	 ALLOW(socket);
	 ALLOW(socketcall);
      }

      if ((SeccompFlags & Seccomp::DIRECTORY) != 0)
      {
	 ALLOW(readdir);
	 ALLOW(getdents);
	 ALLOW(getdents64);
      }

      if (getenv("FAKED_MODE"))
      {
	 ALLOW(semop);
	 ALLOW(semget);
	 ALLOW(msgsnd);
	 ALLOW(msgrcv);
	 ALLOW(msgget);
	 ALLOW(msgctl);
	 ALLOW(ipc);
      }

      for (auto &custom : _config->FindVector("APT::Sandbox::Seccomp::Allow"))
      {
	 if ((rc = seccomp_rule_add(ctx, SCMP_ACT_ALLOW, seccomp_syscall_resolve_name(custom.c_str()), 0)))
	    return _error->FatalE("aptMethod::Configuration", "Cannot allow %s: %s", custom.c_str(), strerror(-rc));
      }

#undef ALLOW

      rc = seccomp_load(ctx);
      if (rc == -EINVAL)
      {
	 std::string msg;
	 strprintf(msg, "aptMethod::Configuration: could not load seccomp policy: %s", strerror(-rc));
	 Warning(std::move(msg));
      }
      else if (rc != 0)
	 return _error->FatalE("aptMethod::Configuration", "could not load seccomp policy: %s", strerror(-rc));

      if (_config->FindB("APT::Sandbox::Seccomp::Print", true))
      {
	 struct sigaction action;
	 memset(&action, 0, sizeof(action));
	 sigemptyset(&action.sa_mask);
	 action.sa_sigaction = [](int, siginfo_t *info, void *) {
	    // Formats a number into a 10 digit ASCII string
	    char buffer[10];
	    int number = info->si_syscall;

	    for (int i = sizeof(buffer) - 1; i >= 0; i--)
	    {
	       buffer[i] = (number % 10) + '0';
	       number /= 10;
	    }

	    constexpr const char *str1 = "\n **** Seccomp prevented execution of syscall ";
	    constexpr const char *str2 = " on architecture ";
	    constexpr const char *str3 = " ****\n";
#ifdef __GNUC__
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-result"
#endif
	    write(2, str1, strlen(str1));
	    write(2, buffer, sizeof(buffer));
	    write(2, str2, strlen(str2));
	    write(2, COMMON_ARCH, strlen(COMMON_ARCH));
	    write(2, str3, strlen(str3));
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
	    _exit(31);
	 };
	 action.sa_flags = SA_SIGINFO;

	 sigaction(SIGSYS, &action, nullptr);
      }
#endif
      return true;
   }

   bool CalculateHashes(FetchItem const * const Itm, FetchResult &Res) const APT_NONNULL(2)
   {
      Hashes Hash(Itm->ExpectedHashes);
      FileFd Fd;
      if (Fd.Open(Res.Filename, FileFd::ReadOnly) == false || Hash.AddFD(Fd) == false)
	 return false;
      Res.TakeHashes(Hash);
      return true;
   }

   void Message(std::string &&msg, std::string code)
   {
      std::unordered_map<std::string, std::string> fields;
      if (Queue != 0)
	 fields.emplace("URI", Queue->Uri);
      else
	 fields.emplace("URI", "<UNKNOWN>");
      if (not UsedMirror.empty())
	 fields.emplace("UsedMirror", UsedMirror);
      fields.emplace("Message", std::move(msg));
      SendMessage(code, std::move(fields));
   }
   void Warning(std::string &&msg)
   {
      return Message(std::move(msg), "104 Warning");
   }
   void Audit(std::string &&msg)
   {
      return Message(std::move(msg), "105 Audit");
   }

   bool TransferModificationTimes(char const * const From, char const * const To, time_t &LastModified) APT_NONNULL(2, 3)
   {
      if (strcmp(To, "/dev/null") == 0)
	 return true;

      struct stat Buf2;
      if (lstat(To, &Buf2) != 0 || S_ISLNK(Buf2.st_mode))
	 return true;

      struct stat Buf;
      if (stat(From, &Buf) != 0)
	 return _error->Errno("stat",_("Failed to stat"));

      // we don't use utimensat here for compatibility reasons: #738567
      struct timeval times[2];
      times[0].tv_sec = Buf.st_atime;
      LastModified = times[1].tv_sec = Buf.st_mtime;
      times[0].tv_usec = times[1].tv_usec = 0;
      if (utimes(To, times) != 0)
	 return _error->Errno("utimes",_("Failed to set modification time"));
      return true;
   }

   // This is a copy of #pkgAcqMethod::Dequeue which is private & hidden
   void Dequeue()
   {
      FetchItem const *const Tmp = Queue;
      Queue = Queue->Next;
      if (Tmp == QueueBack)
	 QueueBack = Queue;
      delete Tmp;
   }
   static std::string URIEncode(std::string const &part)
   {
      // The "+" is encoded as a workaround for an S3 bug (LP#1003633 and LP#1086997)
      return QuoteString(part, _config->Find("Acquire::URIEncode", "+~ ").c_str());
   }

   static std::string DecodeSendURI(std::string const &part)
   {
      if (_config->FindB("Acquire::Send-URI-Encoded", false))
	 return DeQuoteString(part);
      return part;
   }

   aptMethod(std::string &&Binary, char const *const Ver, unsigned long const Flags) APT_NONNULL(3)
       : pkgAcqMethod(Ver, Flags), aptConfigWrapperForMethods(Binary), Binary(std::move(Binary)), SeccompFlags(0)
   {
      try {
	 std::locale::global(std::locale(""));
      } catch (...) {
	 setlocale(LC_ALL, "");
      }
   }
};
class aptAuthConfMethod : public aptMethod
{
   std::vector<std::unique_ptr<FileFd>> authconfs;

   public:
   virtual bool Configuration(std::string Message) APT_OVERRIDE
   {
      if (pkgAcqMethod::Configuration(Message) == false)
	 return false;

      std::string const conf = std::string("Binary::") + Binary;
      _config->MoveSubTree(conf.c_str(), NULL);

      // ignore errors with opening the auth file as it doesn't need to exist
      _error->PushToStack();
      auto const netrc = _config->FindFile("Dir::Etc::netrc");
      if (netrc.empty() == false)
      {
	 authconfs.emplace_back(new FileFd());
	 authconfs.back()->Open(netrc, FileFd::ReadOnly);
      }

      auto const netrcparts = _config->FindDir("Dir::Etc::netrcparts");
      if (netrcparts.empty() == false)
      {
	 for (auto &&netrcpart : GetListOfFilesInDir(netrcparts, "conf", true, true))
	 {
	    authconfs.emplace_back(new FileFd());
	    authconfs.back()->Open(netrcpart, FileFd::ReadOnly);
	 }
      }
      _error->RevertToStack();

      DropPrivsOrDie();

      if (LoadSeccomp() == false)
	 return false;

      return true;
   }

   bool MaybeAddAuthTo(URI &uri)
   {
      bool result = true;

      if (uri.User.empty() == false || uri.Password.empty() == false)
	 return true;

      _error->PushToStack();
      for (auto &authconf : authconfs)
      {
	 if (authconf->IsOpen() == false)
	    continue;
	 if (authconf->Seek(0) == false)
	 {
	    result = false;
	    continue;
	 }

	 result &= MaybeAddAuth(*authconf, uri);
      }

      while (not _error->empty())
      {
	 std::string message;
	 _error->PopMessage(message);
	 Warning(std::move(message));
      }
      _error->RevertToStack();

      return result;
   }

   aptAuthConfMethod(std::string &&Binary, char const *const Ver, unsigned long const Flags) APT_NONNULL(3)
       : aptMethod(std::move(Binary), Ver, Flags) {}
};
#endif