需要一些关于 Android SELinux 构建错误的指南

Question

我目前正在尝试在 RockPi 4 上使用 Quectel EC25 LTE 编译 Android 9。 但目前我被困在 SELinux 实现上。 EC25 RIL 指南告诉我将以下文件修改/添加到 src 树。

• ($Android_src)/system/core/rootdir/ueventd.rc

#quectel port
/dev/ttyUSB* 0660 radio radio
/dev/cdc-wdm* 0660 radio radio
/dev/qcqmi* 0660 radio radio
/dev/cdc-acm* 0660 radio radio

• ($Android_src)/external/sepolicy/file_contexts

/dev/ttyUSB[0-9]* u:object_r:tty_device:s0
/dev/ttyACM[0-9]* u:object_r:tty_device:s0
/system/bin/rild u:object_r:rild_exec:s0
/system/socket/rild u:object_r:rild_socket:s0
/system/socket/rild-debug u:object_r:rild_debug_socket:s0
/system/bin/pppd u:object_r:pppd_exec:s0
/dev/ppp u:object_r:ppp_device:s0

• ($Android_src)/external/sepolicy/rild.te

allow rild default_prop:property_service set;
allow rild device:chr_file { read write ioctl open getattr };
allow rild kernel:system module_request;
allow rild net_radio_prop:property_service set;
allow rild ppp_device:chr_file { read write ioctl open };
allow rild ppp_exec:file { read execute open execute_no_trans };
allow rild radio_prop:property_service set;
allow rild self:capability { net_admin setuid };
allow rild shell_exec:file { read execute open execute_no_trans };
allow rild sysfs_wake_lock:file { open read write };
allow rild system_file:file execute_no_trans;
allow rild system_prop:property_service set;

运行 make 后出现以下错误：

FAILED: out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy
/bin/bash -c "(ASAN_OPTIONS=detect_leaks=0 out/host/linux-x86/bin/checkpolicy -M -c             30 -o out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.tmp out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.recovery.conf ) && (out/host/linux-x86/bin/sepolicy-analyze out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.tmp permissive > out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.permissivedomains ) && (if [ \"userdebug\" = \"user\" -a -s out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.permissivedomains ]; then          echo \"==========\" 1>&2;               echo \"ERROR: permissive domains not allowed in user builds\" 1>&2;             echo \"List of invalid domains:\" 1>&2;               cat out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.permissivedomains 1>&2;           exit 1;                 fi ) && (mv out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.tmp out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy )"
libsepol.report_failure: neverallow on line 532 of system/sepolicy/public/domain.te (or line 10484 of policy.conf) violated by allow rild default_prop:property_service { set };
libsepol.report_failure: neverallow on line 418 of system/sepolicy/public/domain.te (or line 10370 of policy.conf) violated by allow rild device:chr_file { read write open };
libsepol.check_assertions: 2 neverallow failures occurred
Error while expanding policy
out/host/linux-x86/bin/checkpolicy:  loading policy configuration from out/target/product/rk3399/obj/ETC/sepolicy.recovery_intermediates/sepolicy.recovery.conf
[  4% 449/10291] build out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/sepolicy_neverallows
FAILED: out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/sepolicy_neverallows
/bin/bash -c "(rm -f out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/sepolicy_neverallows ) && (ASAN_OPTIONS=detect_leaks=0 out/host/linux-x86/bin/checkpolicy -M -c               30 -o out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/sepolicy_neverallows out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/policy.conf )"
libsepol.report_failure: neverallow on line 532 of system/sepolicy/public/domain.te (or line 10425 of policy.conf) violated by allow rild default_prop:property_service { set };
libsepol.report_failure: neverallow on line 418 of system/sepolicy/public/domain.te (or line 10311 of policy.conf) violated by allow rild device:chr_file { read write open };
libsepol.check_assertions: 2 neverallow failures occurred
Error while expanding policy
out/host/linux-x86/bin/checkpolicy:  loading policy configuration from out/target/product/rk3399/obj/ETC/sepolicy_neverallows_intermediates/policy.conf
[  4% 450/10291] //bionic/libc:libc_bionic_ndk clang++ bionic/bionic_systrace.cpp [arm]
ninja: build stopped: subcommand failed.
10:24:06 ninja failed with: exit status 1

我对 Android/SELinux 不熟悉，但我在 Google 上搜索了该错误，发现设置“neverallow”指令没有任何运气。

我们将不胜感激，

rgds

Answer 1

您的允许规则对于 Android 来说太笼统了。

neverallow 规则有很好的文档记录。从您的错误消息中查看system/sepolicy/public/domain.te:532 和system/sepolicy/public/domain.te:418：

# Require that domains explicitly label unknown properties, and do not allow
# anyone but init to modify unknown properties.
neverallow { domain -init -vendor_init } default_prop:property_service set;

# Don't allow raw read/write/open access to generic devices.
# Rather force a relabel to a more specific type.
neverallow domain device:chr_file { open read write };

您需要找出rild 必须设置的属性，然后添加更具体的允许规则。检查现有的property_contexts 文件是否已经为rild 需要的属性分配了一个类型，或者自己创建它们。 rild 想要访问的设备也需要这样做。

注意：system/sepolicy/public/te_macros 中有宏，这将使您的rild.te 更具可读性。示例：将allow rild default_prop:property_service set 替换为set_prop(rild, default_prop)。