Merge "libfstab_fuzzer: fuzz TransformFstabForDsu() and skip mount logic" am:... (b058c18e) · Commits · e / os / android_system_core

fs_mgr/fs_mgr_fstab.cpp

+14 −7

Original line number	Original line	Diff line number	Diff line
	@@ -754,10 +754,11 @@ bool ReadFstabFromDt(Fstab* fstab, bool verbose) {
	}		}

	#ifdef NO_SKIP_MOUNT		#ifdef NO_SKIP_MOUNT
	bool SkipMountingPartitions(Fstab*, bool) {		static constexpr bool kNoSkipMount = true;
	return true;
	}
	#else		#else
			static constexpr bool kNoSkipMount = false;
			#endif

	// For GSI to skip mounting /product and /system_ext, until there are well-defined interfaces		// For GSI to skip mounting /product and /system_ext, until there are well-defined interfaces
	// between them and /system. Otherwise, the GSI flashed on /system might not be able to work with		// between them and /system. Otherwise, the GSI flashed on /system might not be able to work with
	// device-specific /product and /system_ext. skip_mount.cfg belongs to system_ext partition because		// device-specific /product and /system_ext. skip_mount.cfg belongs to system_ext partition because
	@@ -765,17 +766,24 @@ bool SkipMountingPartitions(Fstab*, bool) {
	// /system/system_ext because GSI is a single system.img that includes the contents of system_ext		// /system/system_ext because GSI is a single system.img that includes the contents of system_ext
	// partition and product partition under /system/system_ext and /system/product, respectively.		// partition and product partition under /system/system_ext and /system/product, respectively.
	bool SkipMountingPartitions(Fstab* fstab, bool verbose) {		bool SkipMountingPartitions(Fstab* fstab, bool verbose) {
			if (kNoSkipMount) {
			return true;
			}

	static constexpr char kSkipMountConfig[] = "/system/system_ext/etc/init/config/skip_mount.cfg";		static constexpr char kSkipMountConfig[] = "/system/system_ext/etc/init/config/skip_mount.cfg";

	std::string skip_config;		std::string skip_mount_config;
	auto save_errno = errno;		auto save_errno = errno;
	if (!ReadFileToString(kSkipMountConfig, &skip_config)) {		if (!ReadFileToString(kSkipMountConfig, &skip_mount_config)) {
	errno = save_errno; // missing file is expected		errno = save_errno; // missing file is expected
	return true;		return true;
	}		}
			return SkipMountWithConfig(skip_mount_config, fstab, verbose);
			}

			bool SkipMountWithConfig(const std::string& skip_mount_config, Fstab* fstab, bool verbose) {
	std::vector<std::string> skip_mount_patterns;		std::vector<std::string> skip_mount_patterns;
	for (const auto& line : Split(skip_config, "\n")) {		for (const auto& line : Split(skip_mount_config, "\n")) {
	if (line.empty() \|\| StartsWith(line, "#")) {		if (line.empty() \|\| StartsWith(line, "#")) {
	continue;		continue;
	}		}
	@@ -801,7 +809,6 @@ bool SkipMountingPartitions(Fstab* fstab, bool verbose) {
	fstab->erase(remove_from, fstab->end());		fstab->erase(remove_from, fstab->end());
	return true;		return true;
	}		}
	#endif

	// Loads the fstab file and combines with fstab entries passed in from device tree.		// Loads the fstab file and combines with fstab entries passed in from device tree.
	bool ReadDefaultFstab(Fstab* fstab) {		bool ReadDefaultFstab(Fstab* fstab) {

fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp

+16 −2

Original line number	Original line	Diff line number	Diff line
	@@ -14,13 +14,27 @@
	// limitations under the License.		// limitations under the License.
	//		//

	#include <cstdio>		#include <string>
			#include <vector>

	#include <fstab/fstab.h>		#include <fstab/fstab.h>
			#include <fuzzer/FuzzedDataProvider.h>

	extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {		extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
	std::string make_fstab_str(reinterpret_cast<const char*>(data), size);		FuzzedDataProvider fdp(data, size);

			std::string make_fstab_str = fdp.ConsumeRandomLengthString();
			std::string dsu_slot = fdp.ConsumeRandomLengthString(30);
			std::vector<std::string> dsu_partitions = {
			fdp.ConsumeRandomLengthString(30),
			fdp.ConsumeRandomLengthString(30),
			};
			std::string skip_mount_config = fdp.ConsumeRemainingBytesAsString();

	android::fs_mgr::Fstab fstab;		android::fs_mgr::Fstab fstab;
	android::fs_mgr::ParseFstabFromString(make_fstab_str, /* proc_mounts = */ false, &fstab);		android::fs_mgr::ParseFstabFromString(make_fstab_str, /* proc_mounts = */ false, &fstab);
			android::fs_mgr::TransformFstabForDsu(&fstab, dsu_slot, dsu_partitions);
			android::fs_mgr::SkipMountWithConfig(skip_mount_config, &fstab, /* verbose = */ false);

	return 0;		return 0;
	}		}

fs_mgr/include_fstab/fstab/fstab.h

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -97,6 +97,8 @@ using Fstab = std::vector<FstabEntry>;
	bool ParseFstabFromString(const std::string& fstab_str, bool proc_mounts, Fstab* fstab_out);		bool ParseFstabFromString(const std::string& fstab_str, bool proc_mounts, Fstab* fstab_out);
	// Exported for testability. Regular users should use ReadDefaultFstab().		// Exported for testability. Regular users should use ReadDefaultFstab().
	std::string GetFstabPath();		std::string GetFstabPath();
			// Exported for testability.
			bool SkipMountWithConfig(const std::string& skip_config, Fstab* fstab, bool verbose);

	bool ReadFstabFromFile(const std::string& path, Fstab* fstab);		bool ReadFstabFromFile(const std::string& path, Fstab* fstab);
	bool ReadFstabFromDt(Fstab* fstab, bool verbose = true);		bool ReadFstabFromDt(Fstab* fstab, bool verbose = true);