this hopefully helps new users get started with formatting.
didn't want to edit the CONTRIBUTING.md file because it already
has a lot of other stuff in there not specific to formatting.
Convert the fs_prehash into a hex ascii string, suitable for environment variables
The initial loader environment is hard-coded, so we use a hard-coded offset for the string
destination. It was a deliberate decision to not include a generic environment variable
handler in the loader because we want to keep the loader compact and with a small attack
surface; a generic environment handling routine would add significant size without much
benefit.
Note that the main purpose for environment variables is for test & debug tooling, where
single programs are run in hosted or emulated environments with arguments passed for fast
debugging. The sole purpose for the environment variable in the loader's context is to
this computed hash onto the userspace environments.
While ideally we'd be as light-fingered as possible on the cryptographic
APIs, unfortunately the reality is we have exactly one hardware
hash engine and we can't just leave the context laying around.
Given that the verification routine would consume the hash, that
would make it unavailable for use later on to pass to the system.
So, this patch set causes the pre-hash algorithm to take a simple
slice-u8 instead of a whole hash context.
The downside of this is it erases the type information about
needing a 64-bit hash to go into the context. This is partially
mitigated with an assert that gives us a run-time check of this
property.
Support passing process arguments in register 2 as part of arguments to
a process.
This requires updating the `InitialProcess` struct that is received from
the loader, and so requires modeifications to be made in tandem.
Signed-off-by: Sean Cross <sean@xobs.io>
Load environment variables to processes by placing the value onto the
stack. This will support additional data in the future such as command
line arguments.
Note this is a breaking change and requires a kernel modification.
Signed-off-by: Sean Cross <sean@xobs.io>
