/*
* Copyright (C) 2015 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.
*/
#define TRACE_TAG ADB
#include "sysdeps.h"
#include <errno.h>
#include <getopt.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <memory>
#include <android-base/logging.h>
#include <android-base/macros.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <libminijail.h>
#include <log/log_properties.h>
#include <scoped_minijail.h>
#include <private/android_filesystem_config.h>
#include "debuggerd/handler.h"
#include "selinux/android.h"
#include "adb.h"
#include "adb_auth.h"
#include "adb_listeners.h"
#include "adb_utils.h"
#include "transport.h"
#include "mdns.h"
static const char* root_seclabel = nullptr;
static bool should_drop_capabilities_bounding_set() {
#if defined(ALLOW_ADBD_ROOT)
if (__android_log_is_debuggable()) {
return false;
}
#endif
return true;
}
static bool should_drop_privileges() {
#if defined(ALLOW_ADBD_ROOT)
// The properties that affect `adb root` and `adb unroot` are ro.secure and
// ro.debuggable. In this context the names don't make the expected behavior
// particularly obvious.
//
// ro.debuggable:
// Allowed to become root, but not necessarily the default. Set to 1 on
// eng and userdebug builds.
//
// ro.secure:
// Drop privileges by default. Set to 1 on userdebug and user builds.
bool ro_secure = android::base::GetBoolProperty("ro.secure", true);
bool ro_debuggable = __android_log_is_debuggable();
// Drop privileges if ro.secure is set...
bool drop = ro_secure;
// ... except "adb root" lets you keep privileges in a debuggable build.
std::string prop = android::base::GetProperty("service.adb.root", "");
bool adb_root = (prop == "1");
bool adb_unroot = (prop == "0");
if (ro_debuggable && adb_root) {
drop = false;
}
// ... and "adb unroot" lets you explicitly drop privileges.
if (adb_unroot) {
drop = true;
}
return drop;
#else
return true; // "adb root" not allowed, always drop privileges.
#endif // ALLOW_ADBD_ROOT
}
static void drop_privileges(int server_port) {
ScopedMinijail jail(minijail_new());
// Add extra groups:
// AID_ADB to access the USB driver
// AID_LOG to read system logs (adb logcat)
// AID_INPUT to diagnose input issues (getevent)
// AID_INET to diagnose network issues (ping)
// AID_NET_BT and AID_NET_BT_ADMIN to diagnose bluetooth (hcidump)
// AID_SDCARD_R to allow reading from the SD card
// AID_SDCARD_RW to allow writing to the SD card
// AID_NET_BW_STATS to read out qtaguid statistics
// AID_READPROC for reading /proc entries across UID boundaries
// AID_UHID for using 'hid' command to read/write to /dev/uhid
gid_t groups[] = {AID_ADB, AID_LOG, AID_INPUT, AID_INET,
AID_NET_BT, AID_NET_BT_ADMIN, AID_SDCARD_R, AID_SDCARD_RW,
AID_NET_BW_STATS, AID_READPROC, AID_UHID};
minijail_set_supplementary_gids(jail.get(), arraysize(groups), groups);
// Don't listen on a port (default 5037) if running in secure mode.
// Don't run as root if running in secure mode.
if (should_drop_privileges()) {
const bool should_drop_caps = should_drop_capabilities_bounding_set();
if (should_drop_caps) {
minijail_use_caps(jail.get(), CAP_TO_MASK(CAP_SETUID) | CAP_TO_MASK(CAP_SETGID));
}
minijail_change_gid(jail.get(), AID_SHELL);
minijail_change_uid(jail.get(), AID_SHELL);
// minijail_enter() will abort if any priv-dropping step fails.
minijail_enter(jail.get());
// Whenever ambient capabilities are being used, minijail cannot
// simultaneously drop the bounding capability set to just
// CAP_SETUID|CAP_SETGID while clearing the inheritable, effective,
// and permitted sets. So we need to do that in two steps.
using ScopedCaps =
std::unique_ptr<std::remove_pointer<cap_t>::type, std::function<void(cap_t)>>;
ScopedCaps caps(cap_get_proc(), &cap_free);
if (cap_clear_flag(caps.get(), CAP_INHERITABLE) == -1) {
PLOG(FATAL) << "cap_clear_flag(INHERITABLE) failed";
}
if (cap_clear_flag(caps.get(), CAP_EFFECTIVE) == -1) {
PLOG(FATAL) << "cap_clear_flag(PEMITTED) failed";
}
if (cap_clear_flag(caps.get(), CAP_PERMITTED) == -1) {
PLOG(FATAL) << "cap_clear_flag(PEMITTED) failed";
}
if (cap_set_proc(caps.get()) != 0) {
PLOG(FATAL) << "cap_set_proc() failed";
}
D("Local port disabled");
} else {
// minijail_enter() will abort if any priv-dropping step fails.
minijail_enter(jail.get());
if (root_seclabel != nullptr) {
if (selinux_android_setcon(root_seclabel) < 0) {
LOG(FATAL) << "Could not set SELinux context";
}
}
std::string error;
std::string local_name =
android::base::StringPrintf("tcp:%d", server_port);
if (install_listener(local_name, "*smartsocket*", nullptr, 0, nullptr, &error)) {
LOG(FATAL) << "Could not install *smartsocket* listener: " << error;
}
}
}
static void setup_port(int port) {
local_init(port);
setup_mdns(port);
}
int adbd_main(int server_port) {
umask(0);
signal(SIGPIPE, SIG_IGN);
init_transport_registration();
// We need to call this even if auth isn't enabled because the file
// descriptor will always be open.
adbd_cloexec_auth_socket();
if (ALLOW_ADBD_NO_AUTH && !android::base::GetBoolProperty("ro.adb.secure", false)) {
auth_required = false;
}
adbd_auth_init();
// Our external storage path may be different than apps, since
// we aren't able to bind mount after dropping root.
const char* adb_external_storage = getenv("ADB_EXTERNAL_STORAGE");
if (adb_external_storage != nullptr) {
setenv("EXTERNAL_STORAGE", adb_external_storage, 1);
} else {
D("Warning: ADB_EXTERNAL_STORAGE is not set. Leaving EXTERNAL_STORAGE"
" unchanged.\n");
}
drop_privileges(server_port);
bool is_usb = false;
if (access(USB_FFS_ADB_EP0, F_OK) == 0) {
// Listen on USB.
usb_init();
is_usb = true;
}
// If one of these properties is set, also listen on that port.
// If one of the properties isn't set and we couldn't listen on usb, listen
// on the default port.
std::string prop_port = android::base::GetProperty("service.adb.tcp.port", "");
if (prop_port.empty()) {
prop_port = android::base::GetProperty("persist.adb.tcp.port", "");
}
int port;
if (sscanf(prop_port.c_str(), "%d", &port) == 1 && port > 0) {
D("using port=%d", port);
// Listen on TCP port specified by service.adb.tcp.port property.
setup_port(port);
} else if (!is_usb) {
// Listen on default port.
setup_port(DEFAULT_ADB_LOCAL_TRANSPORT_PORT);
}
D("adbd_main(): pre init_jdwp()");
init_jdwp();
D("adbd_main(): post init_jdwp()");
D("Event loop starting");
fdevent_loop();
return 0;
}
int main(int argc, char** argv) {
while (true) {
static struct option opts[] = {
{"root_seclabel", required_argument, nullptr, 's'},
{"device_banner", required_argument, nullptr, 'b'},
{"version", no_argument, nullptr, 'v'},
};
int option_index = 0;
int c = getopt_long(argc, argv, "", opts, &option_index);
if (c == -1) {
break;
}
switch (c) {
case 's':
root_seclabel = optarg;
break;
case 'b':
adb_device_banner = optarg;
break;
case 'v':
printf("Android Debug Bridge Daemon version %d.%d.%d\n", ADB_VERSION_MAJOR,
ADB_VERSION_MINOR, ADB_SERVER_VERSION);
return 0;
default:
// getopt already prints "adbd: invalid option -- %c" for us.
return 1;
}
}
close_stdin();
debuggerd_init(nullptr);
adb_trace_init(argv);
D("Handling main()");
return adbd_main(DEFAULT_ADB_PORT);
}