Merge "Add libfstab_fuzzer that fuzzes ReadFstabFile()" (6aa256fd) · Commits · e / os / android_system_core

fs_mgr/fs_mgr_fstab.cpp

+77 −77

Original line number	Diff line number	Diff line
		@@ -442,7 +442,81 @@ std::string GetFstabPath() {
		return "";
		}

		bool ReadFstabFile(FILE* fstab_file, bool proc_mounts, Fstab* fstab_out) {
		/* Extracts <device>s from the by-name symlinks specified in a fstab:
		* /dev/block/<type>/<device>/by-name/<partition>
		*
		* <type> can be: platform, pci or vbd.
		*
		* For example, given the following entries in the input fstab:
		* /dev/block/platform/soc/1da4000.ufshc/by-name/system
		* /dev/block/pci/soc.0/f9824900.sdhci/by-name/vendor
		* it returns a set { "soc/1da4000.ufshc", "soc.0/f9824900.sdhci" }.
		*/
		std::set<std::string> ExtraBootDevices(const Fstab& fstab) {
		std::set<std::string> boot_devices;

		for (const auto& entry : fstab) {
		std::string blk_device = entry.blk_device;
		// Skips blk_device that doesn't conform to the format.
		if (!android::base::StartsWith(blk_device, "/dev/block") \|\|
		android::base::StartsWith(blk_device, "/dev/block/by-name") \|\|
		android::base::StartsWith(blk_device, "/dev/block/bootdevice/by-name")) {
		continue;
		}
		// Skips non-by_name blk_device.
		// /dev/block/<type>/<device>/by-name/<partition>
		// ^ slash_by_name
		auto slash_by_name = blk_device.find("/by-name");
		if (slash_by_name == std::string::npos) continue;
		blk_device.erase(slash_by_name); // erases /by-name/<partition>

		// Erases /dev/block/, now we have <type>/<device>
		blk_device.erase(0, std::string("/dev/block/").size());

		// <type>/<device>
		// ^ first_slash
		auto first_slash = blk_device.find('/');
		if (first_slash == std::string::npos) continue;

		auto boot_device = blk_device.substr(first_slash + 1);
		if (!boot_device.empty()) boot_devices.insert(std::move(boot_device));
		}

		return boot_devices;
		}

		FstabEntry BuildDsuUserdataFstabEntry() {
		constexpr uint32_t kFlags = MS_NOATIME \| MS_NOSUID \| MS_NODEV;

		FstabEntry userdata = {
		.blk_device = "userdata_gsi",
		.mount_point = "/data",
		.fs_type = "ext4",
		.flags = kFlags,
		.reserved_size = 128 * 1024 * 1024,
		};
		userdata.fs_mgr_flags.wait = true;
		userdata.fs_mgr_flags.check = true;
		userdata.fs_mgr_flags.logical = true;
		userdata.fs_mgr_flags.quota = true;
		userdata.fs_mgr_flags.late_mount = true;
		userdata.fs_mgr_flags.formattable = true;
		return userdata;
		}

		bool EraseFstabEntry(Fstab* fstab, const std::string& mount_point) {
		auto iter = std::remove_if(fstab->begin(), fstab->end(),
		[&](const auto& entry) { return entry.mount_point == mount_point; });
		if (iter != fstab->end()) {
		fstab->erase(iter, fstab->end());
		return true;
		}
		return false;
		}

		} // namespace

		bool ReadFstabFromFp(FILE* fstab_file, bool proc_mounts, Fstab* fstab_out) {
		ssize_t len;
		size_t alloc_len = 0;
		char *line = NULL;
		@@ -528,80 +602,6 @@ err:
		return false;
		}

		/* Extracts <device>s from the by-name symlinks specified in a fstab:
		* /dev/block/<type>/<device>/by-name/<partition>
		*
		* <type> can be: platform, pci or vbd.
		*
		* For example, given the following entries in the input fstab:
		* /dev/block/platform/soc/1da4000.ufshc/by-name/system
		* /dev/block/pci/soc.0/f9824900.sdhci/by-name/vendor
		* it returns a set { "soc/1da4000.ufshc", "soc.0/f9824900.sdhci" }.
		*/
		std::set<std::string> ExtraBootDevices(const Fstab& fstab) {
		std::set<std::string> boot_devices;

		for (const auto& entry : fstab) {
		std::string blk_device = entry.blk_device;
		// Skips blk_device that doesn't conform to the format.
		if (!android::base::StartsWith(blk_device, "/dev/block") \|\|
		android::base::StartsWith(blk_device, "/dev/block/by-name") \|\|
		android::base::StartsWith(blk_device, "/dev/block/bootdevice/by-name")) {
		continue;
		}
		// Skips non-by_name blk_device.
		// /dev/block/<type>/<device>/by-name/<partition>
		// ^ slash_by_name
		auto slash_by_name = blk_device.find("/by-name");
		if (slash_by_name == std::string::npos) continue;
		blk_device.erase(slash_by_name); // erases /by-name/<partition>

		// Erases /dev/block/, now we have <type>/<device>
		blk_device.erase(0, std::string("/dev/block/").size());

		// <type>/<device>
		// ^ first_slash
		auto first_slash = blk_device.find('/');
		if (first_slash == std::string::npos) continue;

		auto boot_device = blk_device.substr(first_slash + 1);
		if (!boot_device.empty()) boot_devices.insert(std::move(boot_device));
		}

		return boot_devices;
		}

		FstabEntry BuildDsuUserdataFstabEntry() {
		constexpr uint32_t kFlags = MS_NOATIME \| MS_NOSUID \| MS_NODEV;

		FstabEntry userdata = {
		.blk_device = "userdata_gsi",
		.mount_point = "/data",
		.fs_type = "ext4",
		.flags = kFlags,
		.reserved_size = 128 * 1024 * 1024,
		};
		userdata.fs_mgr_flags.wait = true;
		userdata.fs_mgr_flags.check = true;
		userdata.fs_mgr_flags.logical = true;
		userdata.fs_mgr_flags.quota = true;
		userdata.fs_mgr_flags.late_mount = true;
		userdata.fs_mgr_flags.formattable = true;
		return userdata;
		}

		bool EraseFstabEntry(Fstab* fstab, const std::string& mount_point) {
		auto iter = std::remove_if(fstab->begin(), fstab->end(),
		[&](const auto& entry) { return entry.mount_point == mount_point; });
		if (iter != fstab->end()) {
		fstab->erase(iter, fstab->end());
		return true;
		}
		return false;
		}

		} // namespace

		void TransformFstabForDsu(Fstab* fstab, const std::string& dsu_slot,
		const std::vector<std::string>& dsu_partitions) {
		static constexpr char kDsuKeysDir[] = "/avb";
		@@ -707,7 +707,7 @@ bool ReadFstabFromFile(const std::string& path, Fstab* fstab_out) {
		bool is_proc_mounts = path == "/proc/mounts";

		Fstab fstab;
		if (!ReadFstabFile(fstab_file.get(), is_proc_mounts, &fstab)) {
		if (!ReadFstabFromFp(fstab_file.get(), is_proc_mounts, &fstab)) {
		LERROR << __FUNCTION__ << "(): failed to load fstab from : '" << path << "'";
		return false;
		}
		@@ -762,7 +762,7 @@ bool ReadFstabFromDt(Fstab* fstab, bool verbose) {
		return false;
		}

		if (!ReadFstabFile(fstab_file.get(), false, fstab)) {
		if (!ReadFstabFromFp(fstab_file.get(), false, fstab)) {
		if (verbose) {
		LERROR << __FUNCTION__ << "(): failed to load fstab from kernel:" << std::endl
		<< fstab_buf;

fs_mgr/fuzz/Android.bp

0 → 100644

+28 −0

Original line number	Diff line number	Diff line
		//
		// Copyright (C) 2021 The Android Open Source Project
		//
		// Licensed under the Apache License, Version 2.0 (the "License");
		// you may not use this file except in compliance with the License.
		// You may obtain a copy of the License at
		//
		// http://www.apache.org/licenses/LICENSE-2.0
		//
		// Unless required by applicable law or agreed to in writing, software
		// distributed under the License is distributed on an "AS IS" BASIS,
		// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		// See the License for the specific language governing permissions and
		// limitations under the License.
		//

		cc_fuzz {
		name: "libfstab_fuzzer",
		srcs: [
		"fs_mgr_fstab_fuzzer.cpp",
		],
		static_libs: [
		"libfstab",
		],
		shared_libs: [
		"libbase",
		],
		}

fs_mgr/fuzz/fs_mgr_fstab_fuzzer.cpp

0 → 100644

+30 −0

Original line number	Diff line number	Diff line
		//
		// Copyright (C) 2021 The Android Open Source Project
		//
		// Licensed under the Apache License, Version 2.0 (the "License");
		// you may not use this file except in compliance with the License.
		// You may obtain a copy of the License at
		//
		// http://www.apache.org/licenses/LICENSE-2.0
		//
		// Unless required by applicable law or agreed to in writing, software
		// distributed under the License is distributed on an "AS IS" BASIS,
		// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		// See the License for the specific language governing permissions and
		// limitations under the License.
		//

		#include <cstdio>

		#include <fstab/fstab.h>

		extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
		std::unique_ptr<FILE, decltype(&fclose)> fstab_file(
		fmemopen(static_cast<void>(const_cast<uint8_t>(data)), size, "r"), fclose);
		if (fstab_file == nullptr) {
		return 0;
		}
		android::fs_mgr::Fstab fstab;
		android::fs_mgr::ReadFstabFromFp(fstab_file.get(), /* proc_mounts= */ false, &fstab);
		return 0;
		}

fs_mgr/include_fstab/fstab/fstab.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -99,6 +99,9 @@ struct FstabEntry {
		// Unless explicitly requested, a lookup on mount point should always return the 1st one.
		using Fstab = std::vector<FstabEntry>;

		// Exported for testability. Regular users should use ReadFstabFromfile().
		bool ReadFstabFromFp(FILE* fstab_file, bool proc_mounts, Fstab* fstab_out);

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