src/devices/bin/driver_manager/system_instance.cc

// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "system_instance.h"

#include <dirent.h>
#include <fcntl.h>
#include <fuchsia/boot/llcpp/fidl.h>
#include <fuchsia/hardware/virtioconsole/llcpp/fidl.h>
#include <fuchsia/power/manager/llcpp/fidl.h>
#include <lib/fdio/directory.h>
#include <lib/fdio/spawn-actions.h>
#include <lib/fdio/spawn.h>
#include <lib/fdio/unsafe.h>
#include <lib/fdio/watcher.h>
#include <lib/zircon-internal/paths.h>
#include <lib/zx/debuglog.h>
#include <sys/stat.h>
#include <unistd.h>
#include <zircon/boot/image.h>
#include <zircon/errors.h>
#include <zircon/status.h>
#include <zircon/syscalls/log.h>
#include <zircon/syscalls/policy.h>

#include <vector>

#include <fbl/string_printf.h>
#include <fbl/unique_fd.h>

#include "devfs.h"
#include "fdio.h"
#include "src/devices/lib/log/log.h"
#include "system_state_manager.h"

struct ConsoleStarterArgs {
  SystemInstance* instance;
  llcpp::fuchsia::boot::Arguments::SyncClient* boot_args;
};

struct ServiceStarterArgs {
  SystemInstance* instance;
  Coordinator* coordinator;
};

struct ServiceStarterParams {
  std::string clock_backstop;
};

ServiceStarterParams GetServiceStarterParams(llcpp::fuchsia::boot::Arguments::SyncClient* client) {
  fidl::StringView string_keys[]{
      "clock.backstop",
  };

  auto string_resp = client->GetStrings(fidl::unowned_vec(string_keys));
  ServiceStarterParams ret;
  if (string_resp.ok()) {
    auto& values = string_resp->values;
    ret.clock_backstop = std::string{values[0].data(), values[0].size()};
  }
  return ret;
}

// Wait for the requested file.  Its parent directory must exist.
zx_status_t wait_for_file(const char* path, zx::time deadline) {
  char path_copy[PATH_MAX];
  if (strlen(path) >= PATH_MAX) {
    return ZX_ERR_INVALID_ARGS;
  }
  strcpy(path_copy, path);

  char* last_slash = strrchr(path_copy, '/');
  // Waiting on the root of the fs or paths with no slashes is not supported by this function
  if (last_slash == path_copy || last_slash == nullptr) {
    return ZX_ERR_NOT_SUPPORTED;
  }
  last_slash[0] = 0;
  char* dirname = path_copy;
  char* basename = last_slash + 1;

  auto watch_func = [](int dirfd, int event, const char* fn, void* cookie) -> zx_status_t {
    auto basename = static_cast<const char*>(cookie);
    if (event != WATCH_EVENT_ADD_FILE) {
      return ZX_OK;
    }
    if (!strcmp(fn, basename)) {
      return ZX_ERR_STOP;
    }
    return ZX_OK;
  };

  fbl::unique_fd dirfd(open(dirname, O_RDONLY));
  if (!dirfd.is_valid()) {
    return ZX_ERR_INVALID_ARGS;
  }
  zx_status_t status = fdio_watch_directory(dirfd.get(), watch_func, deadline.get(),
                                            reinterpret_cast<void*>(basename));
  if (status == ZX_ERR_STOP) {
    return ZX_OK;
  }
  return status;
}

SystemInstance::SystemInstance() : launcher_(this) {}

zx_status_t SystemInstance::CreateDriverHostJob(const zx::job& root_job,
                                                zx::job* driver_host_job_out) {
  zx::job driver_host_job;
  zx_status_t status = zx::job::create(root_job, 0u, &driver_host_job);
  if (status != ZX_OK) {
    LOGF(ERROR, "Unable to create driver_host job: %s", zx_status_get_string(status));
    return status;
  }
  // TODO(fxbug.dev/53125): This currently manually restricts AMBIENT_MARK_VMO_EXEC and NEW_PROCESS
  // since this job is created from the root job. The driver_host job should move to being created
  // from something other than the root job. (Although note that it can't simply be created from
  // driver_manager's own job, because that has timer slack job policy automatically applied by the
  // ELF runner.)
  static const zx_policy_basic_v2_t policy[] = {
      {ZX_POL_BAD_HANDLE, ZX_POL_ACTION_ALLOW_EXCEPTION, ZX_POL_OVERRIDE_DENY},
      {ZX_POL_AMBIENT_MARK_VMO_EXEC, ZX_POL_ACTION_DENY, ZX_POL_OVERRIDE_DENY},
      {ZX_POL_NEW_PROCESS, ZX_POL_ACTION_DENY, ZX_POL_OVERRIDE_DENY}};
  status = driver_host_job.set_policy(ZX_JOB_POL_RELATIVE, ZX_JOB_POL_BASIC_V2, &policy,
                                      std::size(policy));
  if (status != ZX_OK) {
    LOGF(ERROR, "Failed to set driver_host job policy: %s", zx_status_get_string(status));
    return status;
  }
  status = driver_host_job.set_property(ZX_PROP_NAME, "zircon-drivers", 15);
  if (status != ZX_OK) {
    LOGF(ERROR, "Failed to set driver_host job property: %s", zx_status_get_string(status));
    return status;
  }
  *driver_host_job_out = std::move(driver_host_job);
  return ZX_OK;
}

void SystemInstance::InstallDevFsIntoNamespace() {
  fdio_ns_t* ns;
  zx_status_t r;
  r = fdio_ns_get_installed(&ns);
  ZX_ASSERT_MSG(r == ZX_OK, "driver_manager: cannot get namespace: %s\n", zx_status_get_string(r));
  r = fdio_ns_bind(ns, "/dev", CloneFs("dev").release());
  ZX_ASSERT_MSG(r == ZX_OK, "driver_manager: cannot bind /dev to namespace: %s\n",
                zx_status_get_string(r));
}

// Thread trampoline for WaitForSystemAvailable, which ServiceStarter spawns
int wait_for_system_available(void* arg) {
  auto args = std::unique_ptr<ServiceStarterArgs>(static_cast<ServiceStarterArgs*>(arg));
  return args->instance->WaitForSystemAvailable(args->coordinator);
}

void SystemInstance::ServiceStarter(Coordinator* coordinator) {
  auto params = GetServiceStarterParams(coordinator->boot_args());
  if (!params.clock_backstop.empty()) {
    auto offset = zx::sec(atoi(params.clock_backstop.data()));
    zx_status_t status =
        zx_clock_adjust(coordinator->root_resource().get(), ZX_CLOCK_UTC, offset.get());
    if (status != ZX_OK) {
      LOGF(ERROR, "Failed to set UTC backstop: %s", zx_status_get_string(status));
    } else {
      LOGF(INFO, "Set UTC backstop to %ld", offset.get());
    }
  }

  zx_status_t status = coordinator->RegisterWithPowerManager(CloneFs("dev"));
  if (status != ZX_OK) {
    LOGF(WARNING, "Unable to RegisterWithPowerManager: %d", status);
  }

  auto starter_args = std::make_unique<ServiceStarterArgs>();
  starter_args->instance = this;
  starter_args->coordinator = coordinator;
  thrd_t t;
  int ret = thrd_create_with_name(&t, wait_for_system_available, starter_args.release(),
                                  "wait-for-system-available");
  if (ret == thrd_success) {
    thrd_detach(t);
  }
}

int SystemInstance::WaitForSystemAvailable(Coordinator* coordinator) {
  // Block this thread until /system-delayed is available. Note that this is
  // only used for coordinating events between fshost and devcoordinator, the
  // /system path is used for loading drivers and appmgr below.
  // TODO: It's pretty wasteful to create a thread just so it can sit blocked in
  // sync I/O opening '/system-delayed'. Once a simple async I/O wrapper exists
  // this should switch to use that
  int fd = open("/system-delayed", O_RDONLY);
  if (fd < 0) {
    LOGF(WARNING, "Unabled to open '/system-delayed', system drivers are disabled");
    return ZX_ERR_IO;
  }
  close(fd);

  // Load in drivers from /system
  coordinator->set_system_available(true);
  coordinator->ScanSystemDrivers();

  return 0;
}

// TODO(fxbug.dev/34633): DEPRECATED. Do not add new dependencies on the fshost loader service!
zx_status_t SystemInstance::clone_fshost_ldsvc(zx::channel* loader) {
  zx::channel remote;
  zx_status_t status = zx::channel::create(0, loader, &remote);
  if (status != ZX_OK) {
    return status;
  }
  return fdio_service_connect("/svc/fuchsia.fshost.Loader", remote.release());
}

zx_status_t DirectoryFilter::Initialize(zx::channel forwarding_directory,
                                        fbl::Span<const char*> allow_filter) {
  forwarding_dir_ = std::move(forwarding_directory);
  for (const auto& name : allow_filter) {
    zx_status_t status = root_dir_->AddEntry(
        name, fbl::MakeRefCounted<fs::Service>([this, name](zx::channel request) {
          return fdio_service_connect_at(forwarding_dir_.get(), name, request.release());
        }));
    if (status != ZX_OK) {
      return status;
    }
  }
  return ZX_OK;
}

zx::channel SystemInstance::CloneFs(const char* path) {
  if (!strcmp(path, "dev")) {
    return devfs_root_clone();
  }
  zx::channel h0, h1;
  if (zx::channel::create(0, &h0, &h1) != ZX_OK) {
    return zx::channel();
  }
  zx_status_t status = ZX_OK;
  if (!strcmp(path, "svc")) {
    status = fdio_service_connect("/svc", h1.release());
  } else if (!strcmp(path, "driver_host_svc")) {
    status = InitializeDriverHostSvcDir();
    if (status == ZX_OK) {
      status = driver_host_svc_->Serve(std::move(h1));
    }
  } else if (!strncmp(path, "dev/", 4)) {
    zx::unowned_channel fs = devfs_root_borrow();
    path += 4;
    status = fdio_open_at(fs->get(), path, FS_READ_WRITE_DIR_FLAGS, h1.release());
  }
  if (status != ZX_OK) {
    LOGF(ERROR, "CloneFs failed for '%s': %s", path, zx_status_get_string(status));
    return zx::channel();
  }
  return h0;
}

zx_status_t SystemInstance::InitializeDriverHostSvcDir() {
  if (driver_host_svc_) {
    return ZX_OK;
  }
  zx_status_t status = loop_.StartThread("driver_host_svc_loop");
  if (status != ZX_OK) {
    return status;
  }
  driver_host_svc_.emplace(loop_.dispatcher());

  zx::channel incoming_services;
  {
    zx::channel server_side;
    status = zx::channel::create(0, &incoming_services, &server_side);
    if (status != ZX_OK) {
      return status;
    }

    status = fdio_service_connect("/svc", server_side.release());
    if (status != ZX_OK) {
      return status;
    }
  }

  const char* kAllowedServices[] = {
      "fuchsia.logger.LogSink",
      "fuchsia.scheduler.ProfileProvider",
      "fuchsia.tracing.provider.Registry",
  };
  return driver_host_svc_->Initialize(std::move(incoming_services), fbl::Span(kAllowedServices));
}