Android11 关于三方应用获取su权限
客户的apk运行报错Cannot run program "su": error=13, Permission denied,查看报错日志,发现是客户apk想使用su命令提权,但是没有权限！
系统这边做修改,让su权限下放到三方应用.
userdebug版本,
adb shell getenforce 为Permissive(宽容模式)
修改之前:/ $ ls -al system/xbin/su
-rwsr-x--- 1 root shell 11192 2024-08-07 01:31 system/xbin/su修改之后:/ $ ls -al system/xbin/su
-rwsr-sr-x 1 root shell 11632 2024-08-02 08:48 system/xbin/sur 只读
w 只写
x 只执行RK Android 11:关闭selinux
+++ b/device/rockchip/common/BoardConfig.mk
@@ -59,7 +59,7 @@ BOARD_BOOT_HEADER_VERSION ?= 2BOARD_MKBOOTIMG_ARGS :=
-BOARD_SELINUX_ENFORCING ?= true
+BOARD_SELINUX_ENFORCING ?= falseAndroid 13:关闭selinux bool IsEnforcing() {return false;// if (ALLOW_PERMISSIVE_SELINUX) {// return StatusFromProperty() == SELINUX_ENFORCING;// }// return true;
}Android 13 diff
+++ b/system/core/libcutils/fs_config.cpp
@@ -86,7 +86,7 @@ static const struct fs_path_config android_dirs[] = {{ 00751, AID_ROOT, AID_SHELL, 0, "system/bin" },{ 00755, AID_ROOT, AID_ROOT, 0, "system/etc/ppp" },{ 00755, AID_ROOT, AID_SHELL, 0, "system/vendor" },
- { 00750, AID_ROOT, AID_SHELL, 0, "system/xbin" },
+ { 00751, AID_ROOT, AID_SHELL, 0, "system/xbin" },//update text { 00751, AID_ROOT, AID_SHELL, 0, "system/apex/*/bin" },{ 00751, AID_ROOT, AID_SHELL, 0, "system_ext/bin" },{ 00751, AID_ROOT, AID_SHELL, 0, "system_ext/apex/*/bin" },
@@ -190,7 +190,7 @@ static const struct fs_path_config android_files[] = {// the following two files are INTENTIONALLY set-uid, but they// are NOT included on user builds.{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" },
- { 04750, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },
+ { 06755, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },//update textSELinux，全称Security-Enhanced Linux，是一种基于Linux内核的安全机制。它通过强制访问控制（MAC）来增强Linux系统的安全性，
对于保护系统资源和防止未经授权访问非常有帮助!
如果不禁用SELinux,完成下面的修改可能会导致设备进入Recovery界面!(这是关键！)
Android14之禁掉Selinux的两种方式(一百七十四)
Android 13 aosp 默认关闭SELinux
修改文件清单
frameworks/base/core/jni/com_android_internal_os_Zygote.cpp
kernel/security/commoncap.c
system/core/libcutils/fs_config.cpp
system/extras/su/su.cpp
diff
+++ b/frameworks/base/core/jni/com_android_internal_os_Zygote.cpp
@@ -658,7 +658,7 @@ static void EnableKeepCapabilities(fail_fn_t fail_fn) {}static void DropCapabilitiesBoundingSet(fail_fn_t fail_fn) {
- for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {;
+ /*for (int i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0) >= 0; i++) {;if (prctl(PR_CAPBSET_DROP, i, 0, 0, 0) == -1) {if (errno == EINVAL) {ALOGE("prctl(PR_CAPBSET_DROP) failed with EINVAL. Please verify "
@@ -667,7 +667,7 @@ static void DropCapabilitiesBoundingSet(fail_fn_t fail_fn) {fail_fn(CREATE_ERROR("prctl(PR_CAPBSET_DROP, %d) failed: %s", i, strerror(errno)));}}
- }
+ }*/}+++ b/system/core/libcutils/fs_config.cpp
@@ -190,7 +190,7 @@ static const struct fs_path_config android_files[] = {// the following two files are INTENTIONALLY set-uid, but they// are NOT included on user builds.{ 06755, AID_ROOT, AID_ROOT, 0, "system/xbin/procmem" },
- { 04750, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },
+ { 06755, AID_ROOT, AID_SHELL, 0, "system/xbin/su" },// the following files have enhanced capabilities and ARE included// in user builds.+++ b/kernel/security/commoncap.c
static int cap_prctl_drop(unsigned long cap)
{struct cred *new;
+/*if (!ns_capable(current_user_ns(), CAP_SETPCAP))return -EPERM;if (!cap_valid(cap))return -EINVAL;
+*/new = prepare_creds();if (!new)return -ENOMEM;//对当前进程的uid 做一个鉴权,当不是 ROOT 或 SHELL 用户的时候直接抛异常,注释掉
+++ b/system/extras/su/su.cpp
@@ -80,8 +80,8 @@ void extract_uidgids(const char* uidgids, uid_t* uid, gid_t* gid, gid_t* gids, i}int main(int argc, char** argv) {
- uid_t current_uid = getuid();
- if (current_uid != AID_ROOT && current_uid != AID_SHELL) error(1, 0, "not allowed");
+ //uid_t current_uid = getuid();
+ //if (current_uid != AID_ROOT && current_uid != AID_SHELL) error(1, 0, "not allowed");// Handle -h and --help.++argv;Android11、12 修改系统获取root权限（su权限）
Android11编译第六弹：user版本增加su+内置root用户