include/vcl/filter/PDFiumLibrary.hxx |
48 ++++++
vcl/source/pdf/PDFiumLibrary.cxx |
56 ++++++++
xmlsecurity/Library_xmlsecurity.mk |
5
xmlsecurity/qa/unit/signing/data/hide-and-replace-shadow-file-signed-2.pdf
|binary
xmlsecurity/qa/unit/signing/signing.cxx |
16 ++
xmlsecurity/source/pdfio/pdfdocument.cxx |
69 ++++++++++
xmlsecurity/workben/pdfverify.cxx |
5
7 files changed, 196 insertions(+), 3 deletions(-)
New commits:
commit d7336df8c4aa949643a63acad80d48291880e161
Author: Miklos Vajna <vmik...@collabora.com>
AuthorDate: Fri Sep 4 17:17:48 2020 +0200
Commit: Caolán McNamara <caol...@redhat.com>
CommitDate: Tue Sep 8 21:34:18 2020 +0200
xmlsecurity: pdf incremental updates that are non-commenting are invalid
I.e. it's OK to add incremental updates for annotation/commenting
purposes and that doesn't invalite existing signatures. Everything else
does.
(cherry picked from commit 61834cd574568613f0b0a2ee099a60fa5a8d9804)
Conflicts:
include/vcl/filter/PDFiumLibrary.hxx
vcl/source/pdf/PDFiumLibrary.cxx
Change-Id: I4607c242b3c6f6b01517b02407e9e7a095e2e069
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/102240
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caol...@redhat.com>
diff --git a/include/vcl/filter/PDFiumLibrary.hxx
b/include/vcl/filter/PDFiumLibrary.hxx
index bc7912c17e81..639c71d61a3d 100644
--- a/include/vcl/filter/PDFiumLibrary.hxx
+++ b/include/vcl/filter/PDFiumLibrary.hxx
@@ -17,9 +17,14 @@
#include <memory>
#include <rtl/instance.hxx>
#include <vcl/dllapi.h>
+#include <vcl/checksum.hxx>
+
+#include <fpdf_doc.h>
namespace vcl::pdf
{
+class PDFiumDocument;
+
class VCL_DLLPUBLIC PDFium final
{
private:
@@ -31,6 +36,49 @@ public:
~PDFium();
};
+class VCL_DLLPUBLIC PDFiumPage final
+{
+private:
+ FPDF_PAGE mpPage;
+
+private:
+ PDFiumPage(const PDFiumPage&) = delete;
+ PDFiumPage& operator=(const PDFiumPage&) = delete;
+
+public:
+ PDFiumPage(FPDF_PAGE pPage)
+ : mpPage(pPage)
+ {
+ }
+
+ ~PDFiumPage()
+ {
+ if (mpPage)
+ FPDF_ClosePage(mpPage);
+ }
+
+ /// Get bitmap checksum of the page, without annotations/commenting.
+ BitmapChecksum getChecksum();
+};
+
+class VCL_DLLPUBLIC PDFiumDocument final
+{
+private:
+ FPDF_DOCUMENT mpPdfDocument;
+
+private:
+ PDFiumDocument(const PDFiumDocument&) = delete;
+ PDFiumDocument& operator=(const PDFiumDocument&) = delete;
+
+public:
+ PDFiumDocument(FPDF_DOCUMENT pPdfDocument);
+ ~PDFiumDocument();
+
+ int getPageCount();
+
+ std::unique_ptr<PDFiumPage> openPage(int nIndex);
+};
+
struct PDFiumLibrary : public rtl::StaticWithInit<std::shared_ptr<PDFium>,
PDFiumLibrary>
{
std::shared_ptr<PDFium> operator()() { return std::make_shared<PDFium>(); }
diff --git a/vcl/source/pdf/PDFiumLibrary.cxx b/vcl/source/pdf/PDFiumLibrary.cxx
index 604807524bf9..861b7dda0acb 100644
--- a/vcl/source/pdf/PDFiumLibrary.cxx
+++ b/vcl/source/pdf/PDFiumLibrary.cxx
@@ -15,6 +15,10 @@
#include <vcl/filter/PDFiumLibrary.hxx>
#include <fpdf_doc.h>
+#include <vcl/bitmap.hxx>
+
+#include <bitmapwriteaccess.hxx>
+
namespace vcl::pdf
{
PDFium::PDFium()
@@ -29,6 +33,58 @@ PDFium::PDFium()
PDFium::~PDFium() { FPDF_DestroyLibrary(); }
+PDFiumDocument::PDFiumDocument(FPDF_DOCUMENT pPdfDocument)
+ : mpPdfDocument(pPdfDocument)
+{
+}
+
+PDFiumDocument::~PDFiumDocument()
+{
+ if (mpPdfDocument)
+ FPDF_CloseDocument(mpPdfDocument);
+}
+
+std::unique_ptr<PDFiumPage> PDFiumDocument::openPage(int nIndex)
+{
+ std::unique_ptr<PDFiumPage> pPDFiumPage;
+ FPDF_PAGE pPage = FPDF_LoadPage(mpPdfDocument, nIndex);
+ if (pPage)
+ {
+ pPDFiumPage = std::make_unique<PDFiumPage>(pPage);
+ }
+ return pPDFiumPage;
+}
+
+int PDFiumDocument::getPageCount() { return FPDF_GetPageCount(mpPdfDocument); }
+
+BitmapChecksum PDFiumPage::getChecksum()
+{
+ size_t nPageWidth = FPDF_GetPageWidth(mpPage);
+ size_t nPageHeight = FPDF_GetPageHeight(mpPage);
+ FPDF_BITMAP pPdfBitmap = FPDFBitmap_Create(nPageWidth, nPageHeight,
/*alpha=*/1);
+ if (!pPdfBitmap)
+ {
+ return 0;
+ }
+
+ // Intentionally not using FPDF_ANNOT here, annotations/commenting is OK
to not affect the
+ // checksum, signature verification wants this.
+ FPDF_RenderPageBitmap(pPdfBitmap, mpPage, /*start_x=*/0, /*start_y=*/0,
nPageWidth, nPageHeight,
+ /*rotate=*/0, /*flags=*/0);
+ Bitmap aBitmap(Size(nPageWidth, nPageHeight), 24);
+ {
+ BitmapScopedWriteAccess pWriteAccess(aBitmap);
+ const auto pPdfBuffer =
static_cast<ConstScanline>(FPDFBitmap_GetBuffer(pPdfBitmap));
+ const int nStride = FPDFBitmap_GetStride(pPdfBitmap);
+ for (size_t nRow = 0; nRow < nPageHeight; ++nRow)
+ {
+ ConstScanline pPdfLine = pPdfBuffer + (nStride * nRow);
+ pWriteAccess->CopyScanline(nRow, pPdfLine,
ScanlineFormat::N32BitTcBgra, nStride);
+ }
+ }
+ return aBitmap.GetChecksum();
+}
+
} // end vcl::pdf
#endif // HAVE_FEATURE_PDFIUM
diff --git a/xmlsecurity/Library_xmlsecurity.mk
b/xmlsecurity/Library_xmlsecurity.mk
index 038276c1725b..823332d3ec64 100644
--- a/xmlsecurity/Library_xmlsecurity.mk
+++ b/xmlsecurity/Library_xmlsecurity.mk
@@ -20,7 +20,10 @@ $(eval $(call gb_Library_add_defs,xmlsecurity,\
-DXMLSECURITY_DLLIMPLEMENTATION \
))
-$(eval $(call gb_Library_use_externals,xmlsecurity,boost_headers))
+$(eval $(call gb_Library_use_externals,xmlsecurity,\
+ boost_headers \
+ $(if $(filter PDFIUM,$(BUILD_TYPE)),pdfium) \
+))
$(eval $(call
gb_Library_set_precompiled_header,xmlsecurity,xmlsecurity/inc/pch/precompiled_xmlsecurity))
diff --git
a/xmlsecurity/qa/unit/signing/data/hide-and-replace-shadow-file-signed-2.pdf
b/xmlsecurity/qa/unit/signing/data/hide-and-replace-shadow-file-signed-2.pdf
new file mode 100644
index 000000000000..f2b1a71096b2
Binary files /dev/null and
b/xmlsecurity/qa/unit/signing/data/hide-and-replace-shadow-file-signed-2.pdf
differ
diff --git a/xmlsecurity/qa/unit/signing/signing.cxx
b/xmlsecurity/qa/unit/signing/signing.cxx
index ed6e55e829d4..8b90f862fb1e 100644
--- a/xmlsecurity/qa/unit/signing/signing.cxx
+++ b/xmlsecurity/qa/unit/signing/signing.cxx
@@ -614,6 +614,22 @@ CPPUNIT_TEST_FIXTURE(SigningTest, testPDFBad)
static_cast<int>(pObjectShell->GetDocumentSignatureState()));
}
+CPPUNIT_TEST_FIXTURE(SigningTest, testPDFHideAndReplace)
+{
+ createDoc(m_directories.getURLFromSrc(DATA_DIRECTORY)
+ + "hide-and-replace-shadow-file-signed-2.pdf");
+ SfxBaseModel* pBaseModel = dynamic_cast<SfxBaseModel*>(mxComponent.get());
+ CPPUNIT_ASSERT(pBaseModel);
+ SfxObjectShell* pObjectShell = pBaseModel->GetObjectShell();
+ CPPUNIT_ASSERT(pObjectShell);
+ // Without the accompanying fix in place, this test would have failed with:
+ // - Expected: 2 (BROKEN)
+ // - Actual : 6 (NOTVALIDATED_PARTIAL_OK)
+ // i.e. a non-commenting update after a signature was not marked as
invalid.
+ CPPUNIT_ASSERT_EQUAL(static_cast<int>(SignatureState::BROKEN),
+
static_cast<int>(pObjectShell->GetDocumentSignatureState()));
+}
+
/// Test a typical PDF which is not signed.
CPPUNIT_TEST_FIXTURE(SigningTest, testPDFNo)
{
diff --git a/xmlsecurity/source/pdfio/pdfdocument.cxx
b/xmlsecurity/source/pdfio/pdfdocument.cxx
index b9d3c4164f90..c132d02cc2b0 100644
--- a/xmlsecurity/source/pdfio/pdfdocument.cxx
+++ b/xmlsecurity/source/pdfio/pdfdocument.cxx
@@ -12,6 +12,9 @@
#include <memory>
#include <vector>
+#include <config_features.h>
+
+#include <vcl/filter/PDFiumLibrary.hxx>
#include <rtl/string.hxx>
#include <rtl/ustrbuf.hxx>
#include <sal/log.hxx>
@@ -20,6 +23,7 @@
#include <svl/sigstruct.hxx>
#include <svl/cryptosign.hxx>
#include <vcl/filter/pdfdocument.hxx>
+#include <vcl/bitmap.hxx>
using namespace com::sun::star;
@@ -133,6 +137,66 @@ bool IsCompleteSignature(SvStream& rStream,
vcl::filter::PDFDocument& rDocument,
size_t nFileEnd = rStream.Tell();
return std::find(rAllEOFs.begin(), rAllEOFs.end(), nFileEnd) !=
rAllEOFs.end();
}
+
+/// Collects the checksum of each page of one version of the PDF.
+void AnalyizeSignatureStream(SvMemoryStream& rStream,
std::vector<BitmapChecksum>& rPageChecksums)
+{
+#if HAVE_FEATURE_PDFIUM
+ auto pPdfium = vcl::pdf::PDFiumLibrary::get();
+ vcl::pdf::PDFiumDocument aPdfDocument(
+ FPDF_LoadMemDocument(rStream.GetData(), rStream.GetSize(),
/*password=*/nullptr));
+
+ int nPageCount = aPdfDocument.getPageCount();
+ for (int nPage = 0; nPage < nPageCount; ++nPage)
+ {
+ std::unique_ptr<vcl::pdf::PDFiumPage>
pPdfPage(aPdfDocument.openPage(nPage));
+ if (!pPdfPage)
+ {
+ return;
+ }
+
+ BitmapChecksum nPageChecksum = pPdfPage->getChecksum();
+ rPageChecksums.push_back(nPageChecksum);
+ }
+#else
+ (void)rStream;
+#endif
+}
+
+/**
+ * Checks if incremental updates after singing performed valid modifications
only.
+ * Annotations/commenting is OK, other changes are not.
+ */
+bool IsValidSignature(SvStream& rStream, vcl::filter::PDFObjectElement*
pSignature)
+{
+ size_t nSignatureEOF = 0;
+ if (!GetEOFOfSignature(pSignature, nSignatureEOF))
+ {
+ return false;
+ }
+
+ SvMemoryStream aSignatureStream;
+ sal_uInt64 nPos = rStream.Tell();
+ rStream.Seek(0);
+ aSignatureStream.WriteStream(rStream, nSignatureEOF);
+ rStream.Seek(nPos);
+ aSignatureStream.Seek(0);
+ std::vector<BitmapChecksum> aSignedPages;
+ AnalyizeSignatureStream(aSignatureStream, aSignedPages);
+
+ SvMemoryStream aFullStream;
+ nPos = rStream.Tell();
+ rStream.Seek(0);
+ aFullStream.WriteStream(rStream);
+ rStream.Seek(nPos);
+ aFullStream.Seek(0);
+ std::vector<BitmapChecksum> aAllPages;
+ AnalyizeSignatureStream(aFullStream, aAllPages);
+
+ // Fail if any page looks different after signing and at the end.
Annotations/commenting doesn't
+ // count, though.
+ return aSignedPages == aAllPages;
+}
}
namespace xmlsecurity::pdfio
@@ -245,6 +309,11 @@ bool ValidateSignature(SvStream& rStream,
vcl::filter::PDFObjectElement* pSignat
return false;
}
rInformation.bPartialDocumentSignature = !IsCompleteSignature(rStream,
rDocument, pSignature);
+ if (!IsValidSignature(rStream, pSignature))
+ {
+ SAL_WARN("xmlsecurity.pdfio", "ValidateSignature: invalid incremental
update detected");
+ return false;
+ }
// At this point there is no obviously missing info to validate the
// signature.
diff --git a/xmlsecurity/workben/pdfverify.cxx
b/xmlsecurity/workben/pdfverify.cxx
index 3076d1c47a43..b5052502573f 100644
--- a/xmlsecurity/workben/pdfverify.cxx
+++ b/xmlsecurity/workben/pdfverify.cxx
@@ -23,6 +23,7 @@
#include <vcl/svapp.hxx>
#include <vcl/graphicfilter.hxx>
#include <vcl/filter/pdfdocument.hxx>
+#include <comphelper/scopeguard.hxx>
#include <pdfio/pdfdocument.hxx>
@@ -80,11 +81,11 @@ int pdfVerify(int nArgc, char** pArgv)
uno::UNO_QUERY);
comphelper::setProcessServiceFactory(xMultiServiceFactory);
+ InitVCL();
+ comphelper::ScopeGuard g([] { DeInitVCL(); });
if (nArgc > 3 && OString(pArgv[3]) == "-p")
{
- InitVCL();
generatePreview(pArgv[1], pArgv[2]);
- DeInitVCL();
return 0;
}
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