android10.0(Q) user版本打开root权限

前言

个人玩家建议采用 magisk 方式直接修补 boot.img 实现 root 即可， 然后搭载 RE 文件管理器可操作 system 相关分区
源码玩家可直接修改 aosp 源码后自己编译 rom 直刷。

文件清单

aosp10\build\core\main.mk
aosp10\system\sepolicy\definitions.mk
aosp10\system\sepolicy\Android.mk
aosp10\system\core\fs_mgr\Android.bp
aosp10\system\core\adb\daemon\main.cpp
aosp10\system\core\adb\Android.bp
aosp10\system\core\init\selinux.cpp
aosp10\system\core\init\Android.mk
aosp10\system\core\init\Android.bp
aosp10\device\google\marlin\xxx\BoardConfig.mk

1、 让进程名称在 AS Logcat 中可见， 通过修改 ro.adb.secure 和 ro.secure

ps： 这步不是必须的， 目的只是在 logcat 中可见进程 pid 和包名， 而且打开 USB 调试时默认授权， 不再弹授权框
build/make/core/main.mk

tags_to_install :=
ifneq (,$(user_variant))
    # Target is secure in user builds.
-   ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=1
+   # ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=1
+   ADDITIONAL_DEFAULT_PROPERTIES += ro.secure=0
    ADDITIONAL_DEFAULT_PROPERTIES += security.perf_harden=1
    ifeq ($(user_variant),user)
-   ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=1
+   # ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=1
+   ADDITIONAL_DEFAULT_PROPERTIES += ro.adb.secure=0
    endif
ifeq ($(user_variant),userdebug)
@@ -251,7 +253,7 @@ ifneq (,$(user_variant))
        tags_to_install += debug
    else
        # Disable debugging in plain user builds.
-       enable_target_debugging :=
+       # enable_target_debugging :=
    endif
    # Disallow mock locations by default for user builds

2、 修改 SELinux权限为 Permissive

找到对应文件 BoardConfig.mk 增加 androidboot.selinux=permissive
device/google/marlin/xxx/BoardConfig.mk

BOARD_KERNEL_CMDLINE += console=ttyHSL0,115200,n8 androidboot.console=ttyHSL0 androidboot.hardware=xxx

继续修改如下三个文件
ALLOW_PERMISSIVE_SELINUX=1
system/core/init/Android.bp

cc_defaults {
    name: "init_defaults",
    cpp_std: "experimental",
    sanitize: {
        misc_undefined: ["signed-integer-overflow"],
    },
    cflags: [
        "-DLOG_UEVENTS=0",
        "-Wall",
        "-Wextra",
        "-Wno-unused-parameter",
        "-Werror",
        "-DALLOW_LOCAL_PROP_OVERRIDE=1",
        "-DALLOW_PERMISSIVE_SELINUX=1",
        "-DREBOOT_BOOTLOADER_ON_PANIC=1",
        "-DWORLD_WRITABLE_KMSG=1",
        "-DDUMP_ON_UMOUNT_FAILURE=1",
        "-DSHUTDOWN_ZERO_TIMEOUT=0",
]   ,

system/core/init/Android.mk

ifneq (,$(filter user userdebug eng,$(TARGET_BUILD_VARIANT)))
init_options += \
-DALLOW_LOCAL_PROP_OVERRIDE=1 \
-DALLOW_PERMISSIVE_SELINUX=1 \
-DREBOOT_BOOTLOADER_ON_PANIC=1 \
-DWORLD_WRITABLE_KMSG=1 \
-DDUMP_ON_UMOUNT_FAILURE=1
else
init_options += \
-DALLOW_LOCAL_PROP_OVERRIDE=0 \
-DALLOW_PERMISSIVE_SELINUX=0 \
-DREBOOT_BOOTLOADER_ON_PANIC=0 \
-DWORLD_WRITABLE_KMSG=0 \
-DDUMP_ON_UMOUNT_FAILURE=0
endif

system/core/init/selinux.cpp

bool IsEnforcing() {
    return false;
    if (ALLOW_PERMISSIVE_SELINUX) {
        return StatusFromCmdline() == SELINUX_ENFORCING;
    }
    return true;

3、 允许 adb 关闭 verity

system/core/adb/Android.bp

@@ -24,7 +24,7 @@ cc_defaults {
        "-Wno-missing-field-initializers",
        "-Wthread-safety",
        "-Wvla",
        "-DADB_HOST=1",
-       "-DALLOW_ADBD_ROOT=0",
+       "-DALLOW_ADBD_ROOT=1",
    ],
    cpp_std: "experimental",
@@ -76,7 +76,14 @@ cc_defaults {
cc_defaults {
    name: "adbd_defaults",
    defaults: ["adb_defaults"],
    //cflags: ["-UADB_HOST", "-DADB_HOST=0"],
    cflags: [
        "-UADB_HOST",
        "-DADB_HOST=0",
        "-UALLOW_ADBD_ROOT",
        "-DALLOW_ADBD_ROOT=1",
        "-DALLOW_ADBD_DISABLE_VERITY",
        "-DALLOW_ADBD_NO_AUTH",
    ],
    product_variables: {
        debuggable: {
            cflags: [
                "-UALLOW_ADBD_ROOT",
                "-DALLOW_ADBD_ROOT=1",
                "-DALLOW_ADBD_DISABLE_VERITY",
                "-DALLOW_ADBD_NO_AUTH",
            ],
        },
    },
} @
@ -403,6 +410,8 @@ cc_library {
    required: ["remount",],
    product_variables: {
        debuggable: {
            required: [
                "remount",
            ],
        },
    },

system/core/adb/daemon/main.cpp

static bool should_drop_capabilities_bounding_set() {
    return false;
    if (ALLOW_ADBD_ROOT || is_device_unlocked()) {
        if (__android_log_is_debuggable()) {
            return false;
        }
    }
    return true;
}
static bool should_drop_privileges() {
    return false;
    // "adb root" not allowed, always drop privileges.
    if (!ALLOW_ADBD_ROOT && !is_device_unlocked()) return true;

4、 修改 adb root 权限

system/core/fs_mgr/Android.bp

whole_static_libs: [
        "liblogwrap",
        "libdm",
        "libfstab",
    ],
    cppflags: [
        "-UALLOW_ADBD_DISABLE_VERITY",
        "-DALLOW_ADBD_DISABLE_VERITY=1",
    ],
    product_variables: {
        debuggable: {
            cppflags: [
                "-UALLOW_ADBD_DISABLE_VERITY",
                "-DALLOW_ADBD_DISABLE_VERITY=1",
            ],
        },
    },
srcs: [
        "fs_mgr_remount.cpp",
    ],
    cppflags: [
        "-UALLOW_ADBD_DISABLE_VERITY",
        "-DALLOW_ADBD_DISABLE_VERITY=1",
    ],
    product_variables: {
        debuggable: {
            cppflags: [
                "-UALLOW_ADBD_DISABLE_VERITY",
                "-DALLOW_ADBD_DISABLE_VERITY=1",
            ],
        },
    },

user 版本启用 overlayfs 来装载 remount 对应分区 user 版本不允许 permissive domains
system/sepolicy/Android.mk

ifneq ($(TARGET_BUILD_VARIANT), eng)
    LOCAL_REQUIRED_MODULES += \
        selinux_denial_metadata \
@@ -978,7 +978,7 @@ $(built_sepolicy_neverallows)
            @mkdir -p $(dir $@)
            $(hide) $< -m -M true -G -c $(POLICYVERS) $(PRIVATE_NEVERALLOW_ARG) $(PRIVATE_CIL_FILES) -o $@.tmp
            $(hide) $(HOST_OUT_EXECUTABLES)/sepolicy-analyze $@.tmp permissive > $@.permissivedomains
-           $(hide) if [ "$(TARGET_BUILD_VARIANT)" = "user" -a -s $@.permissivedomains ]; then \
+           $(hide) if [ "eng" = "user" -a -s $@.permissivedomains ]; then \
                echo "==========" 1>&2; \
                echo "ERROR: permissive domains not allowed in user builds" 1>&2; \
e               cho "List of invalid domains:" 1>&2; \
@@ -1032,7 +1032,7 @@ $(LOCAL_BUILT_MODULE): $(sepolicy.recovery.conf) $(HOST_OUT_EXECUTABLES)/checkpo
            $(hide) $(CHECKPOLICY_ASAN_OPTIONS) $(HOST_OUT_EXECUTABLES)/checkpolicy -M -c \
                $(POLICYVERS) -o $@.tmp $<
            $(hide) $(HOST_OUT_EXECUTABLES)/sepolicy-analyze $@.tmp permissive > $@.permissivedomains
-           $(hide) if [ "$(TARGET_BUILD_VARIANT)" = "user" -a -s $@.permissivedomains ]; then \
+           $(hide) if [ "eng" = "user" -a -s $@.permissivedomains ]; then \
                echo "==========" 1>&2; \
                echo "ERROR: permissive domains not allowed in user builds" 1>&2; \
                echo "List of invalid domains:" 1>&2; \
ifneq ($(filter address,$(SANITIZE_TARGET)),)
    local_fc_files += $(wildcard $(addsuffix /file_contexts_asan, $(PLAT_PRIVATE_POLICY)))
endif
ifneq (,$(filter user userdebug eng,$(TARGET_BUILD_VARIANT)))
    local_fc_files += $(wildcard $(addsuffix /file_contexts_overlayfs, $(PLAT_PRIVATE_POLICY)))
endif
ifneq ($(TARGET_BUILD_VARIANT), eng)
include $(CLEAR_VARS)
LOCAL_MODULE := selinux_denial_metadata
LOCAL_MODULE_CLASS := ETC
LOCAL_MODULE_PATH := $(TARGET_OUT_VENDOR)/etc/selinux

system/sepolicy/definitions.mk

define transform-policy-to-conf
@mkdir -p $(dir $@)
$(hide) m4 --fatal-warnings $(PRIVATE_ADDITIONAL_M4DEFS) \
    -D mls_num_sens=$(PRIVATE_MLS_SENS) -D mls_num_cats=$(PRIVATE_MLS_CATS) \
    -D target_build_variant=eng \
    -D target_with_dexpreopt=$(WITH_DEXPREOPT) \
    -D target_arch=$(PRIVATE_TGT_ARCH) \
    -D target_with_asan=$(PRIVATE_TGT_WITH_ASAN) \
    -D target_with_native_coverage=$(PRIVATE_TGT_WITH_NATIVE_COVERAGE) \
    -D target_full_treble=$(PRIVATE_SEPOLICY_SPLIT) \
    -D target_compatible_property=$(PRIVATE_COMPATIBLE_PROPERTY) \
    -D target_exclude_build_test=$(PRIVATE_EXCLUDE_BUILD_TEST) \
    $(PRIVATE_TGT_RECOVERY) \
-s $^ > $@
endef
.KATI_READONLY := transform-policy-to-conf