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99 lines
2.5 KiB
Plaintext
99 lines
2.5 KiB
Plaintext
The KittenOS NEO Kernel,
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aka "init.lua", or as I like to call
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it, "KNOSKRNL", is what happens when
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someone tries to write a microkernel
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in Lua, and make it efficient.
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Obviously, the result is not entirely
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what would be expected from a kernel
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at all, nevermind a microkernel.
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In particular, it borrows an
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important concept, specifically fast
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yet secure IPC.
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By which I of course mean that the
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IPC consists of programs giving Lua
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values to each other directly, and
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the kernel giving the programs some
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mechanisms to help secure this.
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Not what you expected, I assume.
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The "kn-" group of documents is about
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the KittenOS NEO kernel.
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This is specifically ONLY about the
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kernel, and only about features the
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kernel provides directly.
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As the kernel provides many things to
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everything under it, I believe this
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is of great use.
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It's now time for the notes about the
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kernel side of the boot process.
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Firstly, the startup of sys-init is
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unlike any other - specifically, it
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has a nil callerPid/callerPkg pair.
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This is because no application ran a
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function to create the process - it
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was created by the kernel.
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Secondly, here's what goes on in the
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kernel when an Access is registered,
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and when it's accessed:
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1. The service requests access with
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an AID starting with "r.".
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2. The security policy presumably
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accepts the registration.
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3. A blank registration in the table
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"accesses" is made immediately.
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This registration always fails to
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be retrieved, but exists.
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4. A function is returned to reset
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the registration.
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5. The service calls the function,
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thus the registration is now
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completed.
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6. The user-process requests access
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with an AID starting with "x.",
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everything after matching that
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in the "r." registration.
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7. The security policy presumably
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accepts the use of that API.
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8. The callback in the registration
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is called.
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Its first return value is sent
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back to the user-process.
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If it errors, then nil is given
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instead (the error is not sent).
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Thirdly, the security policy is set
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by getting the kernel global table
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with "k.root", and then changing the
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global "securityPolicy".
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Given this operation is only ever
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performed once in typical use, and
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having control over it is equivalent
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to instant root, it seems fitting
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that it is done this way.
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(Making absolute power absolute is
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also why the kernel loves globals.)
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Finally, the kernel prevents those
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processes that aren't "sys-" from
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calling "sys-" processes.
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-- This is released into
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the public domain.
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-- No warranty is provided,
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implied or otherwise.
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