10c6374e81
The external firmware handler always has root group privileges because it is forked/executed without setgid() by ueventd which has root privileges. This patch calls setgid() with group ID specified in ueventd.rc before execv(). Test: atest CtsInitTestCases Signed-off-by: Suchang Woo <suchang.woo@samsung.com> Change-Id: Id1430e783b0e409d55ac80fe213e81ba099729e2
338 lines
12 KiB
C++
338 lines
12 KiB
C++
/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "firmware_handler.h"
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#include <fcntl.h>
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#include <fnmatch.h>
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#include <glob.h>
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#include <grp.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/sendfile.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <thread>
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#include <android-base/chrono_utils.h>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/scopeguard.h>
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#include <android-base/strings.h>
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#include <android-base/unique_fd.h>
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using android::base::ReadFdToString;
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using android::base::Socketpair;
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using android::base::Split;
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using android::base::Timer;
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using android::base::Trim;
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using android::base::unique_fd;
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using android::base::WriteFully;
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namespace android {
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namespace init {
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namespace {
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bool PrefixMatch(const std::string& pattern, const std::string& path) {
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return android::base::StartsWith(path, pattern);
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}
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bool FnMatch(const std::string& pattern, const std::string& path) {
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return fnmatch(pattern.c_str(), path.c_str(), 0) == 0;
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}
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bool EqualMatch(const std::string& pattern, const std::string& path) {
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return pattern == path;
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}
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} // namespace
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static void LoadFirmware(const std::string& firmware, const std::string& root, int fw_fd,
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size_t fw_size, int loading_fd, int data_fd) {
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// Start transfer.
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WriteFully(loading_fd, "1", 1);
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// Copy the firmware.
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int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
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if (rc == -1) {
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PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << firmware << "' }";
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}
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// Tell the firmware whether to abort or commit.
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const char* response = (rc != -1) ? "0" : "-1";
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WriteFully(loading_fd, response, strlen(response));
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}
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static bool IsBooting() {
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return access("/dev/.booting", F_OK) == 0;
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}
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ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid, gid_t gid,
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std::string handler_path)
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: devpath(std::move(devpath)), uid(uid), gid(gid), handler_path(std::move(handler_path)) {
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auto wildcard_position = this->devpath.find('*');
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if (wildcard_position != std::string::npos) {
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if (wildcard_position == this->devpath.length() - 1) {
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this->devpath.pop_back();
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match = std::bind(PrefixMatch, this->devpath, std::placeholders::_1);
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} else {
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match = std::bind(FnMatch, this->devpath, std::placeholders::_1);
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}
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} else {
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match = std::bind(EqualMatch, this->devpath, std::placeholders::_1);
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}
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}
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ExternalFirmwareHandler::ExternalFirmwareHandler(std::string devpath, uid_t uid,
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std::string handler_path)
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: ExternalFirmwareHandler(devpath, uid, 0, handler_path) {}
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FirmwareHandler::FirmwareHandler(std::vector<std::string> firmware_directories,
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std::vector<ExternalFirmwareHandler> external_firmware_handlers)
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: firmware_directories_(std::move(firmware_directories)),
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external_firmware_handlers_(std::move(external_firmware_handlers)) {}
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Result<std::string> FirmwareHandler::RunExternalHandler(const std::string& handler, uid_t uid,
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gid_t gid, const Uevent& uevent) const {
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unique_fd child_stdout;
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unique_fd parent_stdout;
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if (!Socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, &child_stdout, &parent_stdout)) {
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return ErrnoError() << "Socketpair() for stdout failed";
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}
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unique_fd child_stderr;
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unique_fd parent_stderr;
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if (!Socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, &child_stderr, &parent_stderr)) {
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return ErrnoError() << "Socketpair() for stderr failed";
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}
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signal(SIGCHLD, SIG_DFL);
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auto pid = fork();
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if (pid < 0) {
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return ErrnoError() << "fork() failed";
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}
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if (pid == 0) {
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setenv("FIRMWARE", uevent.firmware.c_str(), 1);
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setenv("DEVPATH", uevent.path.c_str(), 1);
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parent_stdout.reset();
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parent_stderr.reset();
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close(STDOUT_FILENO);
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close(STDERR_FILENO);
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dup2(child_stdout.get(), STDOUT_FILENO);
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dup2(child_stderr.get(), STDERR_FILENO);
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auto args = Split(handler, " ");
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std::vector<char*> c_args;
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for (auto& arg : args) {
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c_args.emplace_back(arg.data());
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}
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c_args.emplace_back(nullptr);
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if (gid != 0) {
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if (setgid(gid) != 0) {
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fprintf(stderr, "setgid() failed: %s", strerror(errno));
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_exit(EXIT_FAILURE);
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}
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}
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if (setuid(uid) != 0) {
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fprintf(stderr, "setuid() failed: %s", strerror(errno));
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_exit(EXIT_FAILURE);
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}
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execv(c_args[0], c_args.data());
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fprintf(stderr, "exec() failed: %s", strerror(errno));
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_exit(EXIT_FAILURE);
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}
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child_stdout.reset();
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child_stderr.reset();
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int status;
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pid_t waited_pid = TEMP_FAILURE_RETRY(waitpid(pid, &status, 0));
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if (waited_pid == -1) {
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return ErrnoError() << "waitpid() failed";
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}
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std::string stdout_content;
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if (!ReadFdToString(parent_stdout.get(), &stdout_content)) {
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return ErrnoError() << "ReadFdToString() for stdout failed";
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}
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std::string stderr_content;
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if (ReadFdToString(parent_stderr.get(), &stderr_content)) {
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auto messages = Split(stderr_content, "\n");
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for (const auto& message : messages) {
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if (!message.empty()) {
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LOG(ERROR) << "External Firmware Handler: " << message;
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}
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}
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} else {
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LOG(ERROR) << "ReadFdToString() for stderr failed";
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}
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status) == EXIT_SUCCESS) {
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return Trim(stdout_content);
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} else {
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return Error() << "exited with status " << WEXITSTATUS(status);
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}
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} else if (WIFSIGNALED(status)) {
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return Error() << "killed by signal " << WTERMSIG(status);
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}
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return Error() << "unexpected exit status " << status;
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}
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std::string FirmwareHandler::GetFirmwarePath(const Uevent& uevent) const {
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for (const auto& external_handler : external_firmware_handlers_) {
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if (external_handler.match(uevent.path)) {
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LOG(INFO) << "Launching external firmware handler '" << external_handler.handler_path
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<< "' for devpath: '" << uevent.path << "' firmware: '" << uevent.firmware
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<< "'";
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auto result = RunExternalHandler(external_handler.handler_path, external_handler.uid,
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external_handler.gid, uevent);
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if (!result.ok()) {
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LOG(ERROR) << "Using default firmware; External firmware handler failed: "
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<< result.error();
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return uevent.firmware;
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}
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if (result->find("..") != std::string::npos) {
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LOG(ERROR) << "Using default firmware; External firmware handler provided an "
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"invalid path, '"
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<< *result << "'";
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return uevent.firmware;
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}
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LOG(INFO) << "Loading firmware '" << *result << "' in place of '" << uevent.firmware
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<< "'";
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return *result;
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}
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}
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LOG(INFO) << "firmware: loading '" << uevent.firmware << "' for '" << uevent.path << "'";
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return uevent.firmware;
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}
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void FirmwareHandler::ProcessFirmwareEvent(const std::string& root,
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const std::string& firmware) const {
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std::string loading = root + "/loading";
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std::string data = root + "/data";
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unique_fd loading_fd(open(loading.c_str(), O_WRONLY | O_CLOEXEC));
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if (loading_fd == -1) {
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PLOG(ERROR) << "couldn't open firmware loading fd for " << firmware;
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return;
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}
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unique_fd data_fd(open(data.c_str(), O_WRONLY | O_CLOEXEC));
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if (data_fd == -1) {
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PLOG(ERROR) << "couldn't open firmware data fd for " << firmware;
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return;
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}
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std::vector<std::string> attempted_paths_and_errors;
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auto TryLoadFirmware = [&](const std::string& firmware_directory) {
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std::string file = firmware_directory + firmware;
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unique_fd fw_fd(open(file.c_str(), O_RDONLY | O_CLOEXEC));
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if (fw_fd == -1) {
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attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
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", open failed: " + strerror(errno));
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return false;
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}
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struct stat sb;
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if (fstat(fw_fd, &sb) == -1) {
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attempted_paths_and_errors.emplace_back("firmware: attempted " + file +
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", fstat failed: " + strerror(errno));
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return false;
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}
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LoadFirmware(firmware, root, fw_fd, sb.st_size, loading_fd, data_fd);
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return true;
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};
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int booting = IsBooting();
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try_loading_again:
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attempted_paths_and_errors.clear();
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if (ForEachFirmwareDirectory(TryLoadFirmware)) {
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return;
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}
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if (booting) {
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// If we're not fully booted, we may be missing
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// filesystems needed for firmware, wait and retry.
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std::this_thread::sleep_for(100ms);
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booting = IsBooting();
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goto try_loading_again;
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}
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LOG(ERROR) << "firmware: could not find firmware for " << firmware;
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for (const auto& message : attempted_paths_and_errors) {
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LOG(ERROR) << message;
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}
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// Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
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write(loading_fd, "-1", 2);
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}
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bool FirmwareHandler::ForEachFirmwareDirectory(
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std::function<bool(const std::string&)> handler) const {
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for (const std::string& firmware_directory : firmware_directories_) {
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if (std::invoke(handler, firmware_directory)) {
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return true;
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}
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}
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glob_t glob_result;
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glob("/apex/*/etc/firmware/", GLOB_MARK, nullptr, &glob_result);
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auto free_glob = android::base::make_scope_guard(std::bind(&globfree, &glob_result));
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for (size_t i = 0; i < glob_result.gl_pathc; i++) {
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char* apex_firmware_directory = glob_result.gl_pathv[i];
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// Filter-out /apex/<name>@<ver> paths. The paths are bind-mounted to
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// /apex/<name> paths, so unless we filter them out, we will look into the
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// same apex twice.
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if (strchr(apex_firmware_directory, '@')) {
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continue;
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}
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if (std::invoke(handler, apex_firmware_directory)) {
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return true;
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}
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}
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return false;
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}
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void FirmwareHandler::HandleUevent(const Uevent& uevent) {
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if (uevent.subsystem != "firmware" || uevent.action != "add") return;
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// Loading the firmware in a child means we can do that in parallel...
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auto pid = fork();
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if (pid == -1) {
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PLOG(ERROR) << "could not fork to process firmware event for " << uevent.firmware;
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}
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if (pid == 0) {
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Timer t;
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auto firmware = GetFirmwarePath(uevent);
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ProcessFirmwareEvent("/sys" + uevent.path, firmware);
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LOG(INFO) << "loading " << uevent.path << " took " << t;
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_exit(EXIT_SUCCESS);
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}
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}
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} // namespace init
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} // namespace android
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