mirror of https://github.com/qpdf/qpdf.git
Handle invalid encryption Length (fixes #333)
This commit is contained in:
Jay Berkenbilt
parent
551dfbf697
commit
c5ed1b8075
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@ -1,5 +1,8 @@
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2019-06-22 Jay Berkenbilt <ejb@ql.org>
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* Handle encrypted files with missing or invalid /Length entries
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in the encryption dictionary.
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* QPDFWriter: allow calling set*EncryptionParameters before
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calling setFilename. Fixes #336.
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@ -935,22 +935,38 @@ QPDF::initializeEncryption()
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pad_short_parameter(Perms, Perms_key_bytes_V5);
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}
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int Length = 40;
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if (encryption_dict.getKey("/Length").isInteger())
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int Length = 0;
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if (V <= 1)
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{
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Length = encryption_dict.getKey("/Length").getIntValueAsInt();
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if (R < 3)
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Length = 40;
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}
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else if (V == 4)
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{
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Length = 128;
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}
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else if (V == 5)
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{
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Length = 256;
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}
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else
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{
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if (encryption_dict.getKey("/Length").isInteger())
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{
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// Force Length to 40 regardless of what the file says.
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Length = 40;
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Length = encryption_dict.getKey("/Length").getIntValueAsInt();
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if ((Length % 8) || (Length < 40) || (Length > 128))
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{
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Length = 0;
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}
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}
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if ((Length % 8) || (Length < 40) || (Length > 256))
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{
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throw QPDFExc(qpdf_e_damaged_pdf, this->m->file->getName(),
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"encryption dictionary",
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this->m->file->getLastOffset(),
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"invalid /Length value in encryption dictionary");
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}
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if (Length == 0)
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{
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Length = 128;
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}
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}
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if (Length == 0)
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{
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// Still no Length? Just take a guess.
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Length = 128;
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}
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this->m->encp->encrypt_metadata = true;
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@ -4353,6 +4353,14 @@ print "\n";
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segmentation fault.
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</para>
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</listitem>
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<listitem>
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<para>
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When reading encrypted files, follow the spec more closely
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regarding encryption key length. This allows qpdf to open
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encrypted files in most cases when they have invalid or
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missing /Length keys in the encryption dictionary.
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</para>
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</listitem>
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</itemizedlist>
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</listitem>
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<listitem>
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@ -3523,7 +3523,7 @@ foreach my $d (@enc_key)
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}
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# Miscellaneous encryption tests
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$n_tests += 2;
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$n_tests += 3;
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$td->runtest("set encryption before set filename",
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{$td->COMMAND => "test_driver 63 minimal.pdf"},
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@ -3534,6 +3534,11 @@ $td->runtest("check file's validity",
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{$td->FILE => "encrypt-before-filename.out",
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$td->EXIT_STATUS => 0},
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$td->NORMALIZE_NEWLINES);
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$td->runtest("handle missing/invalid Length",
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{$td->COMMAND => "qpdf --check bad-encryption-length.pdf"},
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{$td->FILE => "bad-encryption-length.out",
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$td->EXIT_STATUS => 0},
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$td->NORMALIZE_NEWLINES);
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show_ntests();
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# ----------
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@ -0,0 +1,17 @@
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checking bad-encryption-length.pdf
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PDF Version: 1.4
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R = 3
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P = -4
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User password =
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extract for accessibility: allowed
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extract for any purpose: allowed
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print low resolution: allowed
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print high resolution: allowed
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modify document assembly: allowed
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modify forms: allowed
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modify annotations: allowed
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modify other: allowed
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modify anything: allowed
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File is not linearized
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No syntax or stream encoding errors found; the file may still contain
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errors that qpdf cannot detect
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@ -0,0 +1,39 @@
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%PDF-1.4
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%¿÷¢þ
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1 0 obj
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<< /Pages 2 0 R /Type /Catalog >>
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endobj
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2 0 obj
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<< /Count 1 /Kids [ 3 0 R ] /Type /Pages >>
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endobj
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3 0 obj
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<< /Contents 4 0 R /MediaBox [ 0 0 612 792 ] /Parent 2 0 R /Resources << /Font << /F1 5 0 R >> /ProcSet 6 0 R >> /Type /Page >>
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endobj
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4 0 obj
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<< /Length 48 /Filter /FlateDecode >>
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stream
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u|+»[ –ØÄksBþSX¼A*–¥O¨<<3C>®"<22>
J(<28>V¡¢zÉüL[}-šendstream
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endobj
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5 0 obj
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<< /BaseFont /Helvetica /Encoding /WinAnsiEncoding /Name /F1 /Subtype /Type1 /Type /Font >>
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endobj
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6 0 obj
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[ /PDF /Text ]
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endobj
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7 0 obj
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<< /Filter /Standard /Wength 128 /O <77b8fb098022d3ab34237ea5643c08710ea5123fc5f88bf993a68cca5f12b40f> /P -4 /R 3 /U <72ba254904669105f93c01524fceaa320122456a91bae5134273a6db134c87c4> /V 2 >>
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endobj
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xref
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0 8
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0000000000 65535 f
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0000000015 00000 n
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0000000064 00000 n
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0000000123 00000 n
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0000000266 00000 n
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0000000384 00000 n
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0000000491 00000 n
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0000000521 00000 n
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trailer << /Root 1 0 R /Size 8 /ID [<2dc7d3d0f5f5b44e5b39ff85e8a4f70c><2dc7d3d0f5f5b44e5b39ff85e8a4f70c>] /Encrypt 7 0 R >>
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startxref
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728
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%%EOF
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