Remove /Crypt from stream filters unconditionally

When writing a new stream, always remove /Crypt even if we are not otherwise able to filter the stream.

Remove /Crypt from stream filters unconditionally
When writing a new stream, always remove /Crypt even if we are not otherwise able to filter the stream.
Jay Berkenbilt
1 parent 4237a29c
Showing 7 changed files with 102 additions and 4 deletions
libqpdf/QPDFWriter.cc
qpdf/qpdf.testcov
qpdf/qtest/qpdf.test
qpdf/qtest/qpdf/unfilterable-with-crypt-after.out
qpdf/qtest/qpdf/unfilterable-with-crypt-before.out
qpdf/qtest/qpdf/unfilterable-with-crypt.pdf
qpdf/test_driver.cc
@@ -1297,12 +1297,53 @@ QPDFWriter::unparseObject(QPDFObjectHandle object, int level,
             // Suppress /Length since we will write it manually
             object.removeKey("/Length");
  
-            // XXX BUG: /Crypt filters should always be removed.
 	    if (flags & f_filtered)
             {
+                // We will supply our own filter and decode
+                // parameters.
                 object.removeKey("/Filter");
                 object.removeKey("/DecodeParms");
             }
+            else
+            {
+                // Make sure, no matter what else we have, that we
+                // don't have /Crypt in the output filters.
+                QPDFObjectHandle filter = object.getKey("/Filter");
+                QPDFObjectHandle decode_parms = object.getKey("/DecodeParms");
+                if (filter.isOrHasName("/Crypt"))
+                {
+                    if (filter.isName())
+                    {
+                        object.removeKey("/Filter");
+                        object.removeKey("/DecodeParms");
+                    }
+                    else
+                    {
+                        int idx = -1;
+                        for (int i = 0; i < filter.getArrayNItems(); ++i)
+                        {
+                            QPDFObjectHandle item = filter.getArrayItem(i);
+                            if (item.isName() && item.getName() == "/Crypt")
+                            {
+                                idx = i;
+                                break;
+                            }
+                        }
+                        if (idx >= 0)
+                        {
+                            // If filter is an array, then the code in
+                            // QPDF_Stream has already verified that
+                            // DecodeParms and Filters are arrays of
+                            // the same length, but if they weren't
+                            // for some reason, eraseItem does type
+                            // and bounds checking.
+                            QTC::TC("qpdf", "QPDFWriter remove Crypt");
+                            filter.eraseItem(idx);
+                            decode_parms.eraseItem(idx);
+                        }
+                    }
+                }
+            }
         }
  
 	writeString("<<");
@@ -255,3 +255,4 @@ QPDFWriter preserve ADBE 0
 QPDF_encryption skip 0x28 0
 QPDF_encrypt crypt array 0
 QPDF_encryption CFM AESV3 0
+QPDFWriter remove Crypt 0
@@ -1701,12 +1701,12 @@ my @attachments = (
     'enc-XI-attachments-base.pdf',
     'enc-XI-R6,V5,U=attachment,encrypted-attachments.pdf',
     'enc-XI-R6,V5,U=view,attachments,cleartext-metadata.pdf');
-$n_tests += 4 * @attachments;
+$n_tests += 4 * @attachments + 3;
 foreach my $f (@attachments)
 {
     my $pass = '';
     my $tpass = '';
-    if ($f =~ m/U=([^,]+)/)
+    if ($f =~ m/U=([^,\.]+)/)
     {
         $pass = "--password=$1";
         $tpass = $1;
@@ -1726,6 +1726,23 @@ foreach my $f (@attachments)
                  {$td->FILE => "attachments.out", $td->EXIT_STATUS => 0},
                  $td->NORMALIZE_NEWLINES);
 }
+$td->runtest("unfilterable with crypt",
+             {$td->COMMAND =>
+                  "test_driver 36 unfilterable-with-crypt.pdf attachment"},
+             {$td->FILE => "unfilterable-with-crypt-before.out",
+              $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
+unlink "a.pdf";
+$td->runtest("decrypt file",
+             {$td->COMMAND => "qpdf -decrypt --password=attachment" .
+                  " unfilterable-with-crypt.pdf a.pdf"},
+             {$td->STRING => "", $td->EXIT_STATUS => 0});
+$td->runtest("copy of unfilterable with crypt",
+             {$td->COMMAND =>
+                  "test_driver 36 a.pdf attachment"},
+             {$td->FILE => "unfilterable-with-crypt-after.out",
+              $td->EXIT_STATUS => 0},
+             $td->NORMALIZE_NEWLINES);
  
 show_ntests();
 # ----------
+<< /DL 30 /DecodeParms [ null ] /Filter [ /ZlateDecode ] /Length 39 /Params << /CheckSum <c4f73a3ba2b5fef86a4085d6f006eacd> /CreationDate (D:20121229172641-05'00') /ModDate (D:20121229172600) /Size 30 >> /Subtype /text#2fplain >>attachment1.txt:
+This is the first attachment.
+--END--
+test 36 done
+<< /DL 30 /DecodeParms [ << /Name /StdCF >> null ] /Filter [ /Crypt /ZlateDecode ] /Length 64 /Params << /CheckSum <c4f73a3ba2b5fef86a4085d6f006eacd> /CreationDate (D:20121229172641-05'00') /ModDate (D:20121229172600) /Size 30 >> /Subtype /text#2fplain >>attachment1.txt:
+This is the first attachment.
+--END--
+test 36 done
@@ -112,7 +112,7 @@ void runtest(int n, char const* filename1, char const* arg2)
     {
 	pdf.setAttemptRecovery(false);
     }
-    if ((n == 35) && (arg2 != 0))
+    if (((n == 35) || (n == 36)) && (arg2 != 0))
     {
         // arg2 is password
 	pdf.processFile(filename1, arg2);
@@ -1214,6 +1214,37 @@ void runtest(int n, char const* filename1, char const* arg2)
             std::cout << filename << ":\n" << data << "--END--\n";
         }
     }
+    else if (n == 36)
+    {
+        // Extract raw unfilterable attachment
+
+        QPDFObjectHandle root = pdf.getRoot();
+        QPDFObjectHandle names = root.getKey("/Names");
+        QPDFObjectHandle embeddedFiles = names.getKey("/EmbeddedFiles");
+        names = embeddedFiles.getKey("/Names");
+        for (int i = 0; i < names.getArrayNItems(); ++i)
+        {
+            QPDFObjectHandle item = names.getArrayItem(i);
+            if (item.isDictionary() &&
+                item.getKey("/Type").isName() &&
+                (item.getKey("/Type").getName() == "/Filespec") &&
+                item.getKey("/EF").isDictionary() &&
+                item.getKey("/EF").getKey("/F").isStream() &&
+                (item.getKey("/F").getStringValue() == "attachment1.txt"))
+            {
+                std::string filename = item.getKey("/F").getStringValue();
+                QPDFObjectHandle stream = item.getKey("/EF").getKey("/F");
+                Pl_Buffer p1("buffer");
+                Pl_Flate p2("compress", &p1, Pl_Flate::a_inflate);
+                stream.pipeStreamData(&p2, false, false, false);
+                PointerHolder<Buffer> buf = p1.getBuffer();
+                std::string data = std::string(
+                    (char const*)buf->getBuffer(), buf->getSize());
+                std::cout << stream.getDict().unparse()
+                          << filename << ":\n" << data << "--END--\n";
+            }
+        }
+    }
     else
     {
 	throw std::runtime_error(std::string("invalid test ") +