Block app installation - Android Q&A, Help & Troubleshooting

Hello,
I have a daughter and she's using the Galaxy S2, with LineageOS 16 (Android 9) as her phone. I want to block app installation from unknown sources completely, since this is a security threat and she can install anything. I've scavenged Google for about 2 hours and can't find a way to block app installation, even with root.
Uninstalling the PackageInstaller isn't a way, that puts the phone in a bootloop (since PackageInstaller is also used for managing permissions from Android 6)
Disabling unknown sources in the settings isn't enough, since when you open an APK file, it opens a dialog which links you to the settings option
I don't want to lock the entire settings with an AppLock since she needs to access Wi-Fi and other settings
Is there any way to do this?
Blocking certain file types or downloading them would be enough, but I can't find a way to do that either.
Thanks.

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You can use the Play Store's parental controls to restrict or block app installation on the Android device.
Using your child's device, open the Play Store app and tap the menu in the top left corner. Choose Settings and then Parental controls, and turn on the controls. Choose a PIN your kids won't know and tap the kind of content – in this case, apps and games – you want to restrict. Essentially, you've set a password for Google Play free downloads.
Aside from basic downloading, you also want to restrict paid apps and in-app purchases. Apps specifically targeted at kids 12 and under already block unauthorized purchases, but to make it universal, you need to go back to the main Parental Controls menu and choose Require authentication for purchases. Set it to All purchases, which means your PIN must be entered for any purchase.

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No, that's not what I want. She doesn't have Play Store on the device, just the browser, through which she can download .apk files to install apps.

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TramSK said:
No, that's not what I want. She doesn't have Play Store on the device, just the browser, through which she can download .apk files to install apps.
Click to expand...
Click to collapse
If device is rooted another option is to freeze both the Android's "Package Installer" app ( com.android.packageinstaller ) and "Package Manager" - what is an Android service: "Packet Manager" service gets invoked by "Package Installer" app.

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jwoegerbauer said:
If device is rooted another option is to freeze both the Android's "Package Installer" app ( com.android.packageinstaller ) and "Package Manager" - what is an Android service: "Packet Manager" service gets invoked by "Package Installer" app.
Click to expand...
Click to collapse
How would I do that? Wouldn't it cause a bootloop like when I removed it completely?

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TramSK said:
How would I do that? Wouldn't it cause a bootloop like when I removed it completely?
Click to expand...
Click to collapse
A1: By means of ADB
Code:
adb shell pm disable com.android.packageinstaller
A2: Don't know it.

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jwoegerbauer said:
A1: By means of ADB
Code:
adb shell pm disable com.android.packageinstaller
A2: Don't know it.
Click to expand...
Click to collapse
Nope, that's unfortunately not possible. ADB doesn't allow that:
Code:
java.lang.SecurityException: Shell cannot change component state for com.android.packageinstaller/null to 2

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TramSK said:
Nope, that's unfortunately not possible. ADB doesn't allow that:
Code:
java.lang.SecurityException: Shell cannot change component state for com.android.packageinstaller/null to 2
Click to expand...
Click to collapse
The ADB command - as an example above shown by me - should work, if the Android device is rooted means run in superuser-mode ( aka ROOT ). Sorry I forgot to mention it: Didn't know you aren't familiar with this.

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jwoegerbauer said:
The ADB command - as an example above shown by me - should work, if the Android device is rooted means run in superuser-mode ( aka ROOT ). Sorry I forgot to mention it: Didn't know you aren't familiar with this.
Click to expand...
Click to collapse
Ah right, I didn't know I had to run adb in root mode. Let me try. :good:

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That puts the phone in a bootloop, similarly to when I removed it completely. That's not the way unfortunately.

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Wait, perhaps I could disable a specific activity of PackageInstaller? Would that work? I can't find any info on that online, just that you can also disable an activity by doing
Code:
adb shell pm disable <package>/.<activity>

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TramSK said:
Wait, perhaps I could disable a specific activity of PackageInstaller? Would that work? I can't find any info on that online, just that you can also disable an activity by doing
Code:
adb shell pm disable <package>/.<activity>
Click to expand...
Click to collapse
I think you've to revoke app's permission "INSTALL_PACKAGES"
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"lightbox_error": "The requested content cannot be loaded. Please try again later.",
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"lightbox_stop_slideshow": "Stop slideshow",
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"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
Code:
adb shell pm revoke com.android.packageinstaller android.permission.INSTALL_PACKAGES
FYI: Haven't tried it.

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jwoegerbauer said:
I think you've to revoke app's permission "INSTALL_PACKAGES"
Code:
adb shell pm revoke com.android.packageinstaller android.permission.INSTALL_PACKAGES
FYI: Haven't tried it.
Click to expand...
Click to collapse
Nope:
Code:
java.lang.SecurityException: Permission android.permission.INSTALL_PACKAGES is not a changeable permission type
And yes, I'm in SU mode.

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Bump

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Is there really no way to do this in Android? Such a shame, I thought this was achievable.

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Any solutions found? It is like I went through all those commands in exact same order and then I found this post.....

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Working?:
adb shell pm disable com.android.packageinstaller/.PackageInstallerActivity
If the name ever changes, I think we can always use the following to obtain the new component name?
adb shell dumpsys activity activities | grep mResumedActivity
No effect:
adb shell appops set com.android.packageinstaller RUN_IN_BACKGROUND deny
Bootloop:
adb shell cmd package hide com.android.packageinstaller

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SmartestKen said:
Working?:
adb shell pm disable com.android.packageinstaller/.PackageInstallerActivity
If the name ever changes, I think we can always use the following to obtain the new component name?
adb shell dumpsys activity activities | grep mResumedActivity
No effect:
adb shell appops set com.android.packageinstaller RUN_IN_BACKGROUND deny
Bootloop:
adb shell cmd package hide com.android.packageinstaller
Click to expand...
Click to collapse
And what is with one of this steps?
3 Ways to Block Kids From Installing Apps On Their Android Phone | Boomerang - Best Parental and Screen Time Controls for Android mobile devices
I don’t know about your kids, but mine just love to browse the Google Play Store for new apps to download and install. It drives me crazy. They have plenty of apps and games on their devices, and …
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