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/*
* 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 <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <sys/prctl.h>
#include "base/logging.h"
#include "base/stringprintf.h"
#include "cutils/properties.h"
#include "private/android_filesystem_config.h"
#include "selinux/selinux.h"
#include "adb.h"
#include "adb_auth.h"
#include "adb_listeners.h"
#include "transport.h"
static const char* root_seclabel = nullptr;
static void drop_capabilities_bounding_set_if_needed() {
#ifdef ALLOW_ADBD_ROOT
char value[PROPERTY_VALUE_MAX];
property_get("ro.debuggable", value, "");
if (strcmp(value, "1") == 0) {
return;
}
#endif
for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {
if (i == CAP_SETUID || i == CAP_SETGID) {
// CAP_SETUID CAP_SETGID needed by /system/bin/run-as
continue;
}
int err = prctl(PR_CAPBSET_DROP, i, 0, 0, 0);
// Some kernels don't have file capabilities compiled in, and
// prctl(PR_CAPBSET_DROP) returns EINVAL. Don't automatically
// die when we see such misconfigured kernels.
if ((err < 0) && (errno != EINVAL)) {
PLOG(FATAL) << "Could not drop capabilities";
}
}
}
static bool should_drop_privileges() {
#if defined(ALLOW_ADBD_ROOT)
char value[PROPERTY_VALUE_MAX];
// 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.
property_get("ro.secure", value, "1");
bool ro_secure = (strcmp(value, "1") == 0);
property_get("ro.debuggable", value, "");
bool ro_debuggable = (strcmp(value, "1") == 0);
// Drop privileges if ro.secure is set...
bool drop = ro_secure;
property_get("service.adb.root", value, "");
bool adb_root = (strcmp(value, "1") == 0);
bool adb_unroot = (strcmp(value, "0") == 0);
// ...except "adb root" lets you keep privileges in a debuggable build.
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
}
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 && property_get_bool("ro.adb.secure", 0) == 0) {
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");
}
// 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
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};
if (setgroups(sizeof(groups) / sizeof(groups[0]), groups) != 0) {
PLOG(FATAL) << "Could not set supplental groups";
}
/* don't listen on a port (default 5037) if running in secure mode */
/* don't run as root if we are running in secure mode */
if (should_drop_privileges()) {
drop_capabilities_bounding_set_if_needed();
/* then switch user and group to "shell" */
if (setgid(AID_SHELL) != 0) {
PLOG(FATAL) << "Could not setgid";
}
if (setuid(AID_SHELL) != 0) {
PLOG(FATAL) << "Could not setuid";
}
D("Local port disabled");
} else {
if (root_seclabel != nullptr) {
if (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,
&error)) {
LOG(FATAL) << "Could not install *smartsocket* listener: "
<< error;
}
}
bool is_usb = false;
if (access(USB_ADB_PATH, F_OK) == 0 || 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.
char prop_port[PROPERTY_VALUE_MAX];
property_get("service.adb.tcp.port", prop_port, "");
if (prop_port[0] == '\0') {
property_get("persist.adb.tcp.port", prop_port, "");
}
int port;
if (sscanf(prop_port, "%d", &port) == 1 && port > 0) {
D("using port=%d", port);
// Listen on TCP port specified by service.adb.tcp.port property.
local_init(port);
} else if (!is_usb) {
// Listen on default port.
local_init(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;
}
static void close_stdin() {
int fd = unix_open("/dev/null", O_RDONLY);
if (fd == -1) {
perror("failed to open /dev/null, stdin will remain open");
return;
}
dup2(fd, STDIN_FILENO);
unix_close(fd);
}
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 %s\n",
ADB_VERSION_MAJOR, ADB_VERSION_MINOR, ADB_SERVER_VERSION,
ADB_REVISION);
return 0;
default:
// getopt already prints "adbd: invalid option -- %c" for us.
return 1;
}
}
close_stdin();
adb_trace_init(argv);
D("Handling main()");
return adbd_main(DEFAULT_ADB_PORT);
}