Merge "zip_archive: validate data descriptor contents."
diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index a3896fc..eca3ffe 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -48,6 +48,10 @@
using android::base::get_unaligned;
+// Used to turn on crc checks - verify that the content CRC matches the values
+// specified in the local file header and the central directory.
+static const bool kCrcChecksEnabled = false;
+
// This is for windows. If we don't open a file in binary mode, weird
// things will happen.
#ifndef O_BINARY
@@ -483,8 +487,7 @@
delete archive;
}
-static int32_t UpdateEntryFromDataDescriptor(MappedZipFile& mapped_zip,
- ZipEntry *entry) {
+static int32_t ValidateDataDescriptor(MappedZipFile& mapped_zip, ZipEntry* entry) {
uint8_t ddBuf[sizeof(DataDescriptor) + sizeof(DataDescriptor::kOptSignature)];
if (!mapped_zip.ReadData(ddBuf, sizeof(ddBuf))) {
return kIoError;
@@ -494,9 +497,17 @@
const uint16_t offset = (ddSignature == DataDescriptor::kOptSignature) ? 4 : 0;
const DataDescriptor* descriptor = reinterpret_cast<const DataDescriptor*>(ddBuf + offset);
- entry->crc32 = descriptor->crc32;
- entry->compressed_length = descriptor->compressed_size;
- entry->uncompressed_length = descriptor->uncompressed_size;
+ // Validate that the values in the data descriptor match those in the central
+ // directory.
+ if (entry->compressed_length != descriptor->compressed_size ||
+ entry->uncompressed_length != descriptor->uncompressed_size ||
+ entry->crc32 != descriptor->crc32) {
+ ALOGW("Zip: size/crc32 mismatch. expected {%" PRIu32 ", %" PRIu32 ", %" PRIx32
+ "}, was {%" PRIu32 ", %" PRIu32 ", %" PRIx32 "}",
+ entry->compressed_length, entry->uncompressed_length, entry->crc32,
+ descriptor->compressed_size, descriptor->uncompressed_size, descriptor->crc32);
+ return kInconsistentInformation;
+ }
return 0;
}
@@ -564,12 +575,22 @@
// Paranoia: Match the values specified in the local file header
// to those specified in the central directory.
- // Verify that the central directory and local file header have the same general purpose bit
- // flags set.
- if (lfh->gpb_flags != cdr->gpb_flags) {
- ALOGW("Zip: gpb flag mismatch. expected {%04" PRIx16 "}, was {%04" PRIx16 "}",
+ // Warn if central directory and local file header don't agree on the use
+ // of a trailing Data Descriptor. The reference implementation is inconsistent
+ // and appears to use the LFH value during extraction (unzip) but the CD value
+ // while displayng information about archives (zipinfo). The spec remains
+ // silent on this inconsistency as well.
+ //
+ // For now, always use the version from the LFH but make sure that the values
+ // specified in the central directory match those in the data descriptor.
+ //
+ // NOTE: It's also worth noting that unzip *does* warn about inconsistencies in
+ // bit 11 (EFS: The language encoding flag, marking that filename and comment are
+ // encoded using UTF-8). This implementation does not check for the presence of
+ // that flag and always enforces that entry names are valid UTF-8.
+ if ((lfh->gpb_flags & kGPBDDFlagMask) != (cdr->gpb_flags & kGPBDDFlagMask)) {
+ ALOGW("Zip: gpb flag mismatch at bit 3. expected {%04" PRIx16 "}, was {%04" PRIx16 "}",
cdr->gpb_flags, lfh->gpb_flags);
- return kInconsistentInformation;
}
// If there is no trailing data descriptor, verify that the central directory and local file
@@ -932,6 +953,7 @@
const uint32_t uncompressed_length = entry->uncompressed_length;
+ uint64_t crc = 0;
uint32_t compressed_length = entry->compressed_length;
do {
/* read as much as we can */
@@ -964,6 +986,8 @@
if (!writer->Append(&write_buf[0], write_size)) {
// The file might have declared a bogus length.
return kInconsistentInformation;
+ } else {
+ crc = crc32(crc, &write_buf[0], write_size);
}
zstream.next_out = &write_buf[0];
@@ -973,8 +997,13 @@
assert(zerr == Z_STREAM_END); /* other errors should've been caught */
- // stream.adler holds the crc32 value for such streams.
- *crc_out = zstream.adler;
+ // NOTE: zstream.adler is always set to 0, because we're using the -MAX_WBITS
+ // "feature" of zlib to tell it there won't be a zlib file header. zlib
+ // doesn't bother calculating the checksum in that scenario. We just do
+ // it ourselves above because there are no additional gains to be made by
+ // having zlib calculate it for us, since they do it by calling crc32 in
+ // the same manner that we have above.
+ *crc_out = crc;
if (zstream.total_out != uncompressed_length || compressed_length != 0) {
ALOGW("Zip: size mismatch on inflated file (%lu vs %" PRIu32 ")",
@@ -1037,15 +1066,14 @@
}
if (!return_value && entry->has_data_descriptor) {
- return_value = UpdateEntryFromDataDescriptor(archive->mapped_zip, entry);
+ return_value = ValidateDataDescriptor(archive->mapped_zip, entry);
if (return_value) {
return return_value;
}
}
- // TODO: Fix this check by passing the right flags to inflate2 so that
- // it calculates the CRC for us.
- if (entry->crc32 != crc && false) {
+ // Validate that the CRC matches the calculated value.
+ if (kCrcChecksEnabled && (entry->crc32 != static_cast<uint32_t>(crc))) {
ALOGW("Zip: crc mismatch: expected %" PRIu32 ", was %" PRIu64, entry->crc32, crc);
return kInconsistentInformation;
}
diff --git a/libziparchive/zip_archive_test.cc b/libziparchive/zip_archive_test.cc
index 9dd6cc0..42167dd 100644
--- a/libziparchive/zip_archive_test.cc
+++ b/libziparchive/zip_archive_test.cc
@@ -632,6 +632,96 @@
CloseArchive(handle);
}
+// Generated using the following Java program:
+// public static void main(String[] foo) throws Exception {
+// FileOutputStream fos = new
+// FileOutputStream("/tmp/data_descriptor.zip");
+// ZipOutputStream zos = new ZipOutputStream(fos);
+// ZipEntry ze = new ZipEntry("name");
+// ze.setMethod(ZipEntry.DEFLATED);
+// zos.putNextEntry(ze);
+// zos.write("abdcdefghijk".getBytes());
+// zos.closeEntry();
+// zos.close();
+// }
+//
+// cat /tmp/data_descriptor.zip | xxd -i
+//
+static const std::vector<uint8_t> kDataDescriptorZipFile{
+ 0x50, 0x4b, 0x03, 0x04, 0x14, 0x00, 0x08, 0x08, 0x08, 0x00, 0x30, 0x59, 0xce, 0x4a, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x6e, 0x61,
+ 0x6d, 0x65, 0x4b, 0x4c, 0x4a, 0x49, 0x4e, 0x49, 0x4d, 0x4b, 0xcf, 0xc8, 0xcc, 0xca, 0x06, 0x00,
+ //[sig---------------], [crc32---------------], [csize---------------], [size----------------]
+ 0x50, 0x4b, 0x07, 0x08, 0x3d, 0x4e, 0x0e, 0xf9, 0x0e, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00,
+ 0x50, 0x4b, 0x01, 0x02, 0x14, 0x00, 0x14, 0x00, 0x08, 0x08, 0x08, 0x00, 0x30, 0x59, 0xce, 0x4a,
+ 0x3d, 0x4e, 0x0e, 0xf9, 0x0e, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x6e, 0x61,
+ 0x6d, 0x65, 0x50, 0x4b, 0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x32, 0x00,
+ 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00};
+
+// The offsets of the data descriptor in this file, so we can mess with
+// them later in the test.
+static constexpr uint32_t kDataDescriptorOffset = 48;
+static constexpr uint32_t kCSizeOffset = kDataDescriptorOffset + 8;
+static constexpr uint32_t kSizeOffset = kCSizeOffset + 4;
+
+static void ExtractEntryToMemory(const std::vector<uint8_t>& zip_data,
+ std::vector<uint8_t>* entry_out, int32_t* error_code_out) {
+ TemporaryFile tmp_file;
+ ASSERT_NE(-1, tmp_file.fd);
+ ASSERT_TRUE(android::base::WriteFully(tmp_file.fd, &zip_data[0], zip_data.size()));
+ ZipArchiveHandle handle;
+ ASSERT_EQ(0, OpenArchiveFd(tmp_file.fd, "ExtractEntryToMemory", &handle));
+
+ // This function expects a variant of kDataDescriptorZipFile, for look for
+ // an entry whose name is "name" and whose size is 12 (contents =
+ // "abdcdefghijk").
+ ZipEntry entry;
+ ZipString empty_name;
+ SetZipString(&empty_name, "name");
+
+ ASSERT_EQ(0, FindEntry(handle, empty_name, &entry));
+ ASSERT_EQ(static_cast<uint32_t>(12), entry.uncompressed_length);
+
+ entry_out->resize(12);
+ (*error_code_out) = ExtractToMemory(handle, &entry, &((*entry_out)[0]), 12);
+
+ CloseArchive(handle);
+}
+
+TEST(ziparchive, ValidDataDescriptors) {
+ std::vector<uint8_t> entry;
+ int32_t error_code = 0;
+ ExtractEntryToMemory(kDataDescriptorZipFile, &entry, &error_code);
+
+ ASSERT_EQ(0, error_code);
+ ASSERT_EQ(12u, entry.size());
+ ASSERT_EQ('a', entry[0]);
+ ASSERT_EQ('k', entry[11]);
+}
+
+TEST(ziparchive, InvalidDataDescriptors) {
+ std::vector<uint8_t> invalid_csize = kDataDescriptorZipFile;
+ invalid_csize[kCSizeOffset] = 0xfe;
+
+ std::vector<uint8_t> entry;
+ int32_t error_code = 0;
+ ExtractEntryToMemory(invalid_csize, &entry, &error_code);
+
+ ASSERT_GT(0, error_code);
+ ASSERT_STREQ("Inconsistent information", ErrorCodeString(error_code));
+
+ std::vector<uint8_t> invalid_size = kDataDescriptorZipFile;
+ invalid_csize[kSizeOffset] = 0xfe;
+
+ error_code = 0;
+ entry.clear();
+ ExtractEntryToMemory(invalid_csize, &entry, &error_code);
+
+ ASSERT_GT(0, error_code);
+ ASSERT_STREQ("Inconsistent information", ErrorCodeString(error_code));
+}
+
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);