Ktag Operation Not Allowed Link

Some security modules use kernel tags to store security contexts. The setxattr or getxattr system calls may be used to read/write these tags.

Trigger: A process without CAP_MAC_ADMIN or CAP_SYS_ADMIN tries to modify security tags on a file or socket.

Error Context:

setxattr("file.txt", "security.ktag", ...) = -1 EPERM (Operation not permitted)
ktag operation not allowed

If the error appears during development but the code seems correct:

For SLUB debugging, disable with slub_debug=- or reduce to slub_debug=P (partial).

WARNING: Disabling these masks real bugs. Only do this temporarily for validation.

If you maintain a custom driver causing the error: ktag operation not allowed

Modern ECUs often have security mechanisms. One common issue is that the ECU might require a specific checksum correction or a "boot mode" entry that isn't being executed correctly. If the tool attempts to write data that the ECU deems invalid (due to a bad checksum), the operation is blocked.

If the error involves UBIFS:

When you encounter "ktag operation not allowed", follow this systematic approach: