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https://github.com/hrydgard/ppsspp.git
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Henrik Rydgård
f3d7d8bc0c
A crafted zip with a parent-directory ("..") entry name could escape the
destination directory during extraction, writing arbitrary files on the
host (e.g. into startup/autostart folders). ExtractZipContents built the
output path by concatenating the raw zip entry name onto the destination
with no traversal check.
Changes:
- Add HasParentDirComponent() utility in Core/Util/PathUtil and use it in
GameManager::ExtractZipContents to reject entries with a ".." component.
Guard both the directory-creation and file-writing passes.
- Expose ExtractZipContents as public for testing.
- Add unittest/TestZipSlip which crafts a zip with a "../evil.txt" entry
and verifies it is not written outside the destination directory.
90 lines
2.7 KiB
C++
90 lines
2.7 KiB
C++
#include "ext/libzip/zip.h"
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#include "Common/File/FileUtil.h"
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#include "Common/File/Path.h"
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#include "Core/Loaders.h"
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#include "Core/Util/GameManager.h"
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#include "Core/Util/PathUtil.h"
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#include "UnitTest.h"
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static bool TestHasParentDirComponent() {
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EXPECT_TRUE(HasParentDirComponent("../../evil.txt"));
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EXPECT_TRUE(HasParentDirComponent("game/../../evil.txt"));
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EXPECT_TRUE(HasParentDirComponent(".."));
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EXPECT_TRUE(HasParentDirComponent("sub/.."));
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EXPECT_TRUE(HasParentDirComponent("..\\evil.txt"));
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EXPECT_TRUE(HasParentDirComponent("a/b/../.."));
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EXPECT_FALSE(HasParentDirComponent("normal.txt"));
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EXPECT_FALSE(HasParentDirComponent("game/evil.txt"));
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EXPECT_FALSE(HasParentDirComponent("a.b/c.d"));
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EXPECT_FALSE(HasParentDirComponent(""));
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EXPECT_FALSE(HasParentDirComponent("/absolute/path.txt"));
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return true;
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}
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// Creates a zip archive at the given path with one entry of the given name.
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static bool CreateZipWithEntry(const Path &zipPath, const std::string &entryName, const std::string &contents) {
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int errorp = 0;
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zip_t *z = zip_open(zipPath.c_str(), ZIP_CREATE | ZIP_TRUNCATE, &errorp);
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if (!z)
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return false;
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zip_source_t *source = zip_source_buffer(z, contents.data(), contents.size(), 0);
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if (!source) {
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zip_close(z);
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return false;
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}
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if (zip_file_add(z, entryName.c_str(), source, ZIP_FL_ENC_UTF_8) < 0) {
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zip_source_free(source);
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zip_close(z);
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return false;
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}
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return zip_close(z) == 0;
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}
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// Crafts a zip with a parent-directory entry and verifies ExtractZipContents
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// refuses to write outside the destination directory (Zip Slip).
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static bool TestZipSlipExtraction() {
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Path tempRoot = Path("unittest_zip_slip_test");
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File::DeleteDirRecursively(tempRoot);
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EXPECT_TRUE(File::CreateDir(tempRoot));
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Path destDir = tempRoot / "dest";
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EXPECT_TRUE(File::CreateDir(destDir));
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Path zipPath = tempRoot / "bad.zip";
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EXPECT_TRUE(CreateZipWithEntry(zipPath, "../evil.txt", "should not escape"));
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int errorp = 0;
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zip_t *z = zip_open(zipPath.c_str(), 0, &errorp);
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EXPECT_TRUE(z != nullptr);
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ZipFileInfo info;
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info.numFiles = 1;
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info.stripChars = 0;
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info.ignoreMetaFiles = false;
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GameManager manager;
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EXPECT_TRUE(manager.ExtractZipContents(z, destDir, info, true));
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zip_close(z);
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// The malicious file must not have been written outside destDir.
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// A naive "dest / ../evil.txt" would land here.
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EXPECT_FALSE(File::Exists(tempRoot / "evil.txt"));
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// And the actual file should not exist inside destDir either.
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EXPECT_FALSE(File::Exists(destDir / "evil.txt"));
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// Clean up.
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File::Delete(zipPath);
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File::DeleteDirRecursively(tempRoot);
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return true;
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}
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bool TestZipSlip() {
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if (!TestHasParentDirComponent())
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return false;
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if (!TestZipSlipExtraction())
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return false;
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return true;
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}
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