[FR]: Add System UID (1000) / Shizuku-System Mode Support for Intent Firewall

[MURDERDRONESN-520]

Is there an existing issue for this?

• I have searched the existing issues

Describe the problem

When using Blocker with a system-privileged Shizuku (based on CVE-2024-31317, UID=1000), Blocker still shows a warning:

"Unable to acquire root permission. App may not work properly."

However, in this state, Intent Firewall (IFW) mode should work perfectly, because writing rules to /data/system/ifw/ only requires system UID (1000), not root.

But Blocker's current permission check only recognizes root, not system UID, so it refuses to enable IFW mode. This is a missed opportunity for users who cannot or do not want to use traditional root.

Describe the solution

I would like Blocker to detect and support System UID (1000) as a valid privilege level for IFW mode.

Suggested implementation:

1. Add a privilege level detection function:

public static int getPrivilegeLevel() {
    if (isRootAvailable()) return PRIV_ROOT;
    if (Process.myUid() == Process.SYSTEM_UID) return PRIV_SYSTEM;
    return PRIV_NONE;
}

1. Modify startup permission check:

· If System UID is detected → auto-enable IFW mode
· Show an info message instead of a warning, e.g.:
"Running in system mode (UID=1000), IFW features available"
· Skip any root acquisition attempts

1. (Optional) Add a small UI indicator showing current privilege mode: Root / System / None

Additional context

There is an open-source system-privileged Shizuku implementation based on CVE-2024-31317, which grants system UID (1000) instead of shell UID.

Vulnerability details:

· CVE ID: CVE-2024-31317
· Affected Android versions: Android 11, 12, 12L, 13, 14
· Security patch requirement: Only works on devices with security patch BEFORE July 2024 (patches July 2024 and later have been fixed and are NOT vulnerable)
· Description: This vulnerability allows an app to elevate privileges from shell UID (2000) to system UID (1000) under certain conditions

Open-source project reference:

· GitHub repository: https://github.com/mx0341/Shizuku

This system-privileged Shizuku allows apps like Blocker to:

· Write IFW rules to /data/system/ifw/
· Perform pm hide, silent install, etc.
· Avoid traditional root detection (many apps now actively detect and refuse to run in rooted environments)

Warning: This method is for learning/research only. Improper operation (e.g., manually modifying hidden_api_blacklist_exemptions) may cause bootloop and require data wipe (factory reset). The user assumes all responsibility.

Note: This text was co-generated by myself and an AI. I provided the ideas and questions, while the AI assisted with text editing. There may be errors, please verify carefully.