Yrurtj

Is there a possibility to place variables under the custody of the Linux kernel?

E.g. counters that may only be incremented, variables that can be written to but only read after authentication.

Ideally with persistency after reboot and unalterable between boots.

I could think of a kernel module that allows access to the variables via /proc filesystem and storing the values in the kernel keyring.

However I could not find a solution for this.

Usecase would be e.g. software eFuses https://en.wikipedia.org/wiki/EFUSE and the ability to securely store variables from user space.

You have got Redis for storing data structures and getting them after reboot, as the service saves the cache when going down.

https://redis.io

Redis does not use proc, runs at user land level, and you talk with it by default at 6379/TCP.

There are also APIs/extensions for a few languages, including python and PHP.

You can do also some diagnostics, and send some commands by telneting to it/wget/curl.

It can be password protected.

to install it on Debian

sudo apt-get install redis-server

.

Redis is an open source (BSD licensed), in-memory data structure
store, used as a database, cache and message broker. It supports data
structures such as strings, hashes, lists, sets, sorted sets with
range queries, bitmaps, hyperloglogs and geospatial indexes with
radius queries. Redis has built-in replication, Lua scripting, LRU
eviction, transactions and different levels of on-disk persistence...

From this Redis Quick Guide

Redis is an open source, advanced key-value store and an apt solution
for building highperformance, scalable web applications.

Redis has three main peculiarities that sets it apart.

Redis holds its database entirely in the memory, using the disk only
for persistence.

Redis has a relatively rich set of data types when compared to many
key-value data stores.

Redis can replicate data to any number of slaves.

Attending to your original question and subsequent comments, the answer is no.

Is there a possibility to place variables under the custody of the Linux kernel?

Ideally with persistency after reboot and unalterable between boots.

I could think of a kernel module that allows access to the variables via /proc filesystem and storing the values in the kernel keyring.

If you are looking for a way to store data securely, then you need a database of some kind and the means to ensure integrity of the data stored - which usually involves cryptography. This in itself creates several problems that need to be addressed carefully, such as key management, storage encryption, etc.

The kernel offers very few options for persistent data storage. There's keyring as mentioned which might help, but its purpose is slightly different. I have never studied the security of this kind of subsystem, so I would not be able to comment about its strength for your use case.

You have Redis for putting away information structures and getting them after reboot, as the administration spares the store while going down. Just go to the below link is helpful for you.

https://hackr.io/tutorials/learn-redis