summaryrefslogtreecommitdiff
path: root/gnu/packages/patches/icecat-bug-1413868-pt1.patch
blob: 18382dc33acce0429d2967db8571683be40f7faa (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
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
Based on <https://hg.mozilla.org/releases/mozilla-esr52/rev/431fa5dd4016>
Adapted to apply cleanly to GNU IceCat.

# HG changeset patch
# User Honza Bambas <honzab.moz@firemni.cz>
# Date 1528830658 14400
# Node ID 431fa5dd4016bdab7e4bb0d3c4df85468fe337b0
# Parent  e8e9e1ef79f2a18c61ec1b87cfb214c8d4960f8e
Bug 1413868. r=valentin, a=RyanVM

diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -4,16 +4,17 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/dom/ContentParent.h"
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/ipc/GeckoChildProcessHost.h"
 
 #include "mozilla/ArrayUtils.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/FilePreferences.h"
 #include "mozilla/ChaosMode.h"
 #include "mozilla/IOInterposer.h"
 #include "mozilla/Likely.h"
 #include "mozilla/MemoryChecking.h"
 #include "mozilla/Poison.h"
 #include "mozilla/Preferences.h"
 #include "mozilla/ScopeExit.h"
 #include "mozilla/Services.h"
@@ -4304,16 +4305,20 @@ XREMain::XRE_mainRun()
       // Need to write out the fact that the profile has been removed and potentially
       // that the selected/default profile changed.
       mProfileSvc->Flush();
     }
   }
 
   mDirProvider.DoStartup();
 
+  // As FilePreferences need the profile directory, we must initialize right here.
+  mozilla::FilePreferences::InitDirectoriesWhitelist();
+  mozilla::FilePreferences::InitPrefs();
+
   OverrideDefaultLocaleIfNeeded();
 
 #ifdef MOZ_CRASHREPORTER
   nsCString userAgentLocale;
   // Try a localized string first. This pref is always a localized string in
   // IceCatMobile, and might be elsewhere, too.
   if (NS_SUCCEEDED(Preferences::GetLocalizedCString("general.useragent.locale", &userAgentLocale))) {
     CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("useragent_locale"), userAgentLocale);
diff --git a/toolkit/xre/nsEmbedFunctions.cpp b/toolkit/xre/nsEmbedFunctions.cpp
--- a/toolkit/xre/nsEmbedFunctions.cpp
+++ b/toolkit/xre/nsEmbedFunctions.cpp
@@ -46,16 +46,17 @@
 #include "nsX11ErrorHandler.h"
 #include "nsGDKErrorHandler.h"
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/message_loop.h"
 #include "base/process_util.h"
 #include "chrome/common/child_process.h"
 
+#include "mozilla/FilePreferences.h"
 #include "mozilla/ipc/BrowserProcessSubThread.h"
 #include "mozilla/ipc/GeckoChildProcessHost.h"
 #include "mozilla/ipc/IOThreadChild.h"
 #include "mozilla/ipc/ProcessChild.h"
 #include "ScopedXREEmbed.h"
 
 #include "mozilla/plugins/PluginProcessChild.h"
 #include "mozilla/dom/ContentProcess.h"
@@ -680,16 +681,18 @@ XRE_InitChildProcess(int aArgc,
       ::SetProcessShutdownParameters(0x280 - 1, SHUTDOWN_NORETRY);
 #endif
 
 #if defined(MOZ_SANDBOX) && defined(XP_WIN)
       // We need to do this after the process has been initialised, as
       // InitLoggingIfRequired may need access to prefs.
       mozilla::sandboxing::InitLoggingIfRequired(aChildData->ProvideLogFunction);
 #endif
+      mozilla::FilePreferences::InitDirectoriesWhitelist();
+      mozilla::FilePreferences::InitPrefs();
 
       OverrideDefaultLocaleIfNeeded();
 
 #if defined(MOZ_CRASHREPORTER)
 #if defined(MOZ_CONTENT_SANDBOX) && !defined(MOZ_WIDGET_GONK)
       AddContentSandboxLevelAnnotation();
 #endif
 #endif
diff --git a/xpcom/io/FilePreferences.cpp b/xpcom/io/FilePreferences.cpp
new file mode 100644
--- /dev/null
+++ b/xpcom/io/FilePreferences.cpp
@@ -0,0 +1,271 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FilePreferences.h"
+
+#include "mozilla/Preferences.h"
+#include "nsAppDirectoryServiceDefs.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsDirectoryServiceUtils.h"
+
+namespace mozilla {
+namespace FilePreferences {
+
+static bool sBlockUNCPaths = false;
+typedef nsTArray<nsString> Paths;
+
+static Paths& PathArray()
+{
+  static Paths sPaths;
+  return sPaths;
+}
+
+static void AllowDirectory(char const* directory)
+{
+  nsCOMPtr<nsIFile> file;
+  NS_GetSpecialDirectory(directory, getter_AddRefs(file));
+  if (!file) {
+    return;
+  }
+
+  nsString path;
+  if (NS_FAILED(file->GetTarget(path))) {
+    return;
+  }
+
+  // The whitelist makes sense only for UNC paths, because this code is used
+  // to block only UNC paths, hence, no need to add non-UNC directories here
+  // as those would never pass the check.
+  if (!StringBeginsWith(path, NS_LITERAL_STRING("\\\\"))) {
+    return;
+  }
+
+  if (!PathArray().Contains(path)) {
+    PathArray().AppendElement(path);
+  }
+}
+
+void InitPrefs()
+{
+  sBlockUNCPaths = Preferences::GetBool("network.file.disable_unc_paths", false);
+}
+
+void InitDirectoriesWhitelist()
+{
+  // NS_GRE_DIR is the installation path where the binary resides.
+  AllowDirectory(NS_GRE_DIR);
+  // NS_APP_USER_PROFILE_50_DIR and NS_APP_USER_PROFILE_LOCAL_50_DIR are the two
+  // parts of the profile we store permanent and local-specific data.
+  AllowDirectory(NS_APP_USER_PROFILE_50_DIR);
+  AllowDirectory(NS_APP_USER_PROFILE_LOCAL_50_DIR);
+}
+
+namespace { // anon
+
+class Normalizer
+{
+public:
+  Normalizer(const nsAString& aFilePath, const char16_t aSeparator);
+  bool Get(nsAString& aNormalizedFilePath);
+
+private:
+  bool ConsumeItem();
+  bool ConsumeSeparator();
+  bool IsEOF() { return mFilePathCursor == mFilePathEnd; }
+
+  bool ConsumeName();
+  bool CheckParentDir();
+  bool CheckCurrentDir();
+
+  nsString::const_char_iterator mFilePathCursor;
+  nsString::const_char_iterator mFilePathEnd;
+
+  nsDependentSubstring mItem;
+  char16_t const mSeparator;
+  nsTArray<nsDependentSubstring> mStack;
+};
+
+Normalizer::Normalizer(const nsAString& aFilePath, const char16_t aSeparator)
+  : mFilePathCursor(aFilePath.BeginReading())
+  , mFilePathEnd(aFilePath.EndReading())
+  , mSeparator(aSeparator)
+{
+}
+
+bool Normalizer::ConsumeItem()
+{
+  if (IsEOF()) {
+    return false;
+  }
+
+  nsString::const_char_iterator nameBegin = mFilePathCursor;
+  while (mFilePathCursor != mFilePathEnd) {
+    if (*mFilePathCursor == mSeparator) {
+      break; // don't include the separator
+    }
+    ++mFilePathCursor;
+  }
+
+  mItem.Rebind(nameBegin, mFilePathCursor);
+  return true;
+}
+
+bool Normalizer::ConsumeSeparator()
+{
+  if (IsEOF()) {
+    return false;
+  }
+
+  if (*mFilePathCursor != mSeparator) {
+    return false;
+  }
+
+  ++mFilePathCursor;
+  return true;
+}
+
+bool Normalizer::Get(nsAString& aNormalizedFilePath)
+{
+  aNormalizedFilePath.Truncate();
+
+  if (IsEOF()) {
+    return true;
+  }
+  if (ConsumeSeparator()) {
+    aNormalizedFilePath.Append(mSeparator);
+  }
+
+  if (IsEOF()) {
+    return true;
+  }
+  if (ConsumeSeparator()) {
+    aNormalizedFilePath.Append(mSeparator);
+  }
+
+  while (!IsEOF()) {
+    if (!ConsumeName()) {
+      return false;
+    }
+  }
+
+  for (auto const& name : mStack) {
+    aNormalizedFilePath.Append(name);
+  }
+
+  return true;
+}
+
+bool Normalizer::ConsumeName()
+{
+  if (!ConsumeItem()) {
+    return true;
+  }
+
+  if (CheckCurrentDir()) {
+    return true;
+  }
+
+  if (CheckParentDir()) {
+    if (!mStack.Length()) {
+      // This means there are more \.. than valid names
+      return false;
+    }
+
+    mStack.RemoveElementAt(mStack.Length() - 1);
+    return true;
+  }
+
+  if (mItem.IsEmpty()) {
+    // this means an empty name (a lone slash), which is illegal
+    return false;
+  }
+
+  if (ConsumeSeparator()) {
+    mItem.Rebind(mItem.BeginReading(), mFilePathCursor);
+  }
+  mStack.AppendElement(mItem);
+
+  return true;
+}
+
+bool Normalizer::CheckCurrentDir()
+{
+  if (mItem == NS_LITERAL_STRING(".")) {
+    ConsumeSeparator();
+    // EOF is acceptable
+    return true;
+  }
+
+  return false;
+}
+
+bool Normalizer::CheckParentDir()
+{
+  if (mItem == NS_LITERAL_STRING("..")) {
+    ConsumeSeparator();
+    // EOF is acceptable
+    return true;
+  }
+
+  return false;
+}
+
+} // anon
+
+bool IsBlockedUNCPath(const nsAString& aFilePath)
+{
+  if (!sBlockUNCPaths) {
+    return false;
+  }
+
+  if (!StringBeginsWith(aFilePath, NS_LITERAL_STRING("\\\\"))) {
+    return false;
+  }
+
+  nsAutoString normalized;
+  if (!Normalizer(aFilePath, L'\\').Get(normalized)) {
+    // Broken paths are considered invalid and thus inaccessible
+    return true;
+  }
+
+  for (const auto& allowedPrefix : PathArray()) {
+    if (StringBeginsWith(normalized, allowedPrefix)) {
+      if (normalized.Length() == allowedPrefix.Length()) {
+        return false;
+      }
+      if (normalized[allowedPrefix.Length()] == L'\\') {
+        return false;
+      }
+
+      // When we are here, the path has a form "\\path\prefixevil"
+      // while we have an allowed prefix of "\\path\prefix".
+      // Note that we don't want to add a slash to the end of a prefix
+      // so that opening the directory (no slash at the end) still works.
+      break;
+    }
+  }
+
+  return true;
+}
+
+void testing::SetBlockUNCPaths(bool aBlock)
+{
+  sBlockUNCPaths = aBlock;
+}
+
+void testing::AddDirectoryToWhitelist(nsAString const & aPath)
+{
+  PathArray().AppendElement(aPath);
+}
+
+bool testing::NormalizePath(nsAString const & aPath, nsAString & aNormalized)
+{
+  Normalizer normalizer(aPath, L'\\');
+  return normalizer.Get(aNormalized);
+}
+
+} // ::FilePreferences
+} // ::mozilla
diff --git a/xpcom/io/FilePreferences.h b/xpcom/io/FilePreferences.h
new file mode 100644
--- /dev/null
+++ b/xpcom/io/FilePreferences.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+* License, v. 2.0. If a copy of the MPL was not distributed with this
+* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsIObserver.h"
+
+namespace mozilla {
+namespace FilePreferences {
+
+void InitPrefs();
+void InitDirectoriesWhitelist();
+bool IsBlockedUNCPath(const nsAString& aFilePath);
+
+namespace testing {
+
+void SetBlockUNCPaths(bool aBlock);
+void AddDirectoryToWhitelist(nsAString const& aPath);
+bool NormalizePath(nsAString const & aPath, nsAString & aNormalized);
+
+}
+
+} // FilePreferences
+} // mozilla
diff --git a/xpcom/io/moz.build b/xpcom/io/moz.build
--- a/xpcom/io/moz.build
+++ b/xpcom/io/moz.build
@@ -79,24 +79,26 @@ EXPORTS += [
     'nsUnicharInputStream.h',
     'nsWildCard.h',
     'SlicedInputStream.h',
     'SpecialSystemDirectory.h',
 ]
 
 EXPORTS.mozilla += [
     'Base64.h',
+    'FilePreferences.h',
     'SnappyCompressOutputStream.h',
     'SnappyFrameUtils.h',
     'SnappyUncompressInputStream.h',
 ]
 
 UNIFIED_SOURCES += [
     'Base64.cpp',
     'crc32c.c',
+    'FilePreferences.cpp',
     'nsAnonymousTemporaryFile.cpp',
     'nsAppFileLocationProvider.cpp',
     'nsBinaryStream.cpp',
     'nsDirectoryService.cpp',
     'nsEscape.cpp',
     'nsInputStreamTee.cpp',
     'nsIOUtil.cpp',
     'nsLinebreakConverter.cpp',
diff --git a/xpcom/io/nsLocalFileWin.cpp b/xpcom/io/nsLocalFileWin.cpp
--- a/xpcom/io/nsLocalFileWin.cpp
+++ b/xpcom/io/nsLocalFileWin.cpp
@@ -41,16 +41,17 @@
 #include  <stdio.h>
 #include  <stdlib.h>
 #include  <mbstring.h>
 
 #include "nsXPIDLString.h"
 #include "prproces.h"
 #include "prlink.h"
 
+#include "mozilla/FilePreferences.h"
 #include "mozilla/Mutex.h"
 #include "SpecialSystemDirectory.h"
 
 #include "nsTraceRefcnt.h"
 #include "nsXPCOMCIDInternal.h"
 #include "nsThreadUtils.h"
 #include "nsXULAppAPI.h"
 
@@ -1162,16 +1163,20 @@ nsLocalFile::InitWithPath(const nsAStrin
   char16_t secondChar = *(++begin);
 
   // just do a sanity check.  if it has any forward slashes, it is not a Native path
   // on windows.  Also, it must have a colon at after the first char.
   if (FindCharInReadable(L'/', begin, end)) {
     return NS_ERROR_FILE_UNRECOGNIZED_PATH;
   }
 
+  if (FilePreferences::IsBlockedUNCPath(aFilePath)) {
+    return NS_ERROR_FILE_ACCESS_DENIED;
+  }
+
   if (secondChar != L':' && (secondChar != L'\\' || firstChar != L'\\')) {
     return NS_ERROR_FILE_UNRECOGNIZED_PATH;
   }
 
   if (secondChar == L':') {
     // Make sure we have a valid drive, later code assumes the drive letter
     // is a single char a-z or A-Z.
     if (PathGetDriveNumberW(aFilePath.Data()) == -1) {
@@ -1974,16 +1979,20 @@ nsLocalFile::CopySingleFile(nsIFile* aSo
     bool path1Remote, path2Remote;
     if (!IsRemoteFilePath(filePath.get(), path1Remote) ||
         !IsRemoteFilePath(destPath.get(), path2Remote) ||
         path1Remote || path2Remote) {
       dwCopyFlags |= COPY_FILE_NO_BUFFERING;
     }
   }
 
+  if (FilePreferences::IsBlockedUNCPath(destPath)) {
+    return NS_ERROR_FILE_ACCESS_DENIED;
+  }
+
   if (!move) {
     copyOK = ::CopyFileExW(filePath.get(), destPath.get(), nullptr,
                            nullptr, nullptr, dwCopyFlags);
   } else {
     copyOK = ::MoveFileExW(filePath.get(), destPath.get(),
                            MOVEFILE_REPLACE_EXISTING);
 
     // Check if copying the source file to a different volume,
diff --git a/xpcom/tests/gtest/TestFilePreferencesWin.cpp b/xpcom/tests/gtest/TestFilePreferencesWin.cpp
new file mode 100644
--- /dev/null
+++ b/xpcom/tests/gtest/TestFilePreferencesWin.cpp
@@ -0,0 +1,141 @@
+#include "gtest/gtest.h"
+
+#include "mozilla/FilePreferences.h"
+#include "nsIFile.h"
+#include "nsXPCOMCID.h"
+
+TEST(FilePreferencesWin, Normalization)
+{
+  nsAutoString normalized;
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("foo"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("foo"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\foo"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\foo"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("foo\\some"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("foo\\some"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.\\foo"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\."), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.\\."), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\bar"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\bar\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\."), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\bar\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\.\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\bar\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\..\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\.."), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\foo\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\..\\bar\\..\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\..\\bar"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\bar"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\..\\..\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\.\\..\\.\\..\\"), normalized);
+  ASSERT_TRUE(normalized == NS_LITERAL_STRING("\\\\"));
+
+  bool result;
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.."), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\..\\"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.\\..\\"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\\\bar"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\foo\\bar\\..\\..\\..\\..\\"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\\\"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\.\\\\"), normalized);
+  ASSERT_FALSE(result);
+
+  result = mozilla::FilePreferences::testing::NormalizePath(
+    NS_LITERAL_STRING("\\\\..\\\\"), normalized);
+  ASSERT_FALSE(result);
+}
+
+TEST(FilePreferencesWin, AccessUNC)
+{
+  nsCOMPtr<nsIFile> lf = do_CreateInstance(NS_LOCAL_FILE_CONTRACTID);
+
+  nsresult rv;
+
+  mozilla::FilePreferences::testing::SetBlockUNCPaths(false);
+
+  rv = lf->InitWithPath(NS_LITERAL_STRING("\\\\nice\\..\\evil\\share"));
+  ASSERT_EQ(rv, NS_OK);
+
+  mozilla::FilePreferences::testing::SetBlockUNCPaths(true);
+
+  rv = lf->InitWithPath(NS_LITERAL_STRING("\\\\nice\\..\\evil\\share"));
+  ASSERT_EQ(rv, NS_ERROR_FILE_ACCESS_DENIED);
+
+  mozilla::FilePreferences::testing::AddDirectoryToWhitelist(NS_LITERAL_STRING("\\\\nice"));
+
+  rv = lf->InitWithPath(NS_LITERAL_STRING("\\\\nice\\share"));
+  ASSERT_EQ(rv, NS_OK);
+
+  rv = lf->InitWithPath(NS_LITERAL_STRING("\\\\nice\\..\\evil\\share"));
+  ASSERT_EQ(rv, NS_ERROR_FILE_ACCESS_DENIED);
+}
diff --git a/xpcom/tests/gtest/moz.build b/xpcom/tests/gtest/moz.build
--- a/xpcom/tests/gtest/moz.build
+++ b/xpcom/tests/gtest/moz.build
@@ -51,16 +51,21 @@ UNIFIED_SOURCES += [
 if CONFIG['MOZ_DEBUG'] and CONFIG['OS_ARCH'] not in ('WINNT') and CONFIG['OS_TARGET'] != 'Android':
     # FIXME bug 523392: TestDeadlockDetector doesn't like Windows
     # Bug 1054249: Doesn't work on Android
     UNIFIED_SOURCES += [
         'TestDeadlockDetector.cpp',
         'TestDeadlockDetectorScalability.cpp',
     ]
 
+if CONFIG['OS_TARGET'] == 'WINNT':
+    UNIFIED_SOURCES += [
+        'TestFilePreferencesWin.cpp',
+    ]
+
 if CONFIG['WRAP_STL_INCLUDES'] and not CONFIG['CLANG_CL']:
     UNIFIED_SOURCES += [
         'TestSTLWrappers.cpp',
     ]
 
 # Compile TestAllocReplacement separately so Windows headers don't pollute
 # the global namespace for other files.
 SOURCES += [