adb/daemon/main.cpp - android-core - Git at Google

 /*
  * 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);
 }
	/*
	* 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);
	}