mount kernel filesystems if run as pid1 #18

Vincinator · 2022-09-28T11:30:17Z

Hi aurae community,

This PR adds first steps to make auraed boot as pid1, mainly mounting the kernel filesystems (devfs, procfs and sysfs), but also some minor fixes to make auraed boot without kernel panic.

Fixes kernel panic due to a rust panic thrown by syslog creation (missing unix sockets [1])
- The rust panic causes auraed to stop, and if started as pid1 the kernel will in turn also panic because the init process ended.
Fixes hack/hack.mk for zsh users
Adds a SystemRuntime (analog to AuraedRuntime), which handles system preparation.
- SystemRuntime Case: not-pid1
  - assume a systemd environment (currently only unix socket /var/run/syslog)
- SystemRuntime Case: pid1
  - initializes logging without unix socket dependency. Using syslog crate would require creation of unix socket first, and I suggest to discuss this first if there is a use case to have a unix socket for logging.
  - mounts file based kernel interfaces
  - devfs, sysfs, procfs
Added helper functions for basic file io (currently for devfs, sysfs, procfs interfaces)
- get content of e.g. /dev, /sys or /proc
- or /sys/class/net/ to see available network interfaces

ToDo:

Discuss Logging targets
- Same log targets for all SystemRuntime cases?
Network initialization
Stop auraed in pid1 case gracefully (kernel halt syscall to shutdown or reboot)

How to test

Steps to run auraed as pid in a qemu vm are documented in the hack/README.md. Copy pasted them here:

make build-container
make kernel
make initramfs

# create `vm-br0` bridge on your machine:
make network

# run auraed in a VM as pid 1:
make virsh-start virsh-console virsh-stop

# exit VM console with Ctrl+]

Links

[1] https://docs.rs/syslog/latest/src/syslog/lib.rs.html#232-243

* Mount devfs, sysfs and procfs * (optional and early draft): Basic fileio helper * depends on walkdir crate * only use syslog logger if not run as pid1 * Syslog requires unix sockets /dev/log or /var/run/syslog. * These sockets need to be set up first by auraed if we want to use them. Suggesting a discussion first.

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Vincinator · 2022-09-28T12:04:32Z

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krisnova · 2022-09-29T00:05:41Z

src/system/init.rs

@@ -0,0 +1,93 @@
+use log::*;


Can we add the header please?

krisnova · 2022-09-29T00:09:46Z

src/system/init.rs

+// To Discuss (TODO):
+//      The "syslog" logger requires unix sockets.
+//      Syslog assumes that either /dev/log or /var/run/syslog are available [1].
+//      We need to discuss if there is a use case to log via unix sockets,


In general the project should support the ability to log to a unix socket, however this is a fine starting point for right now.

Opened #24 to track the work.

krisnova · 2022-09-29T00:14:06Z

src/system/mod.rs

+    std::process::id()
+}
+
+pub fn print_logo() {


So I love the logo! I already tweeted it! https://twitter.com/krisnova/status/1575274332665815044

Can we break this into 2 functions?

pub fn banner() -> String { format!("...") }

and a 2nd function that prints the output of the first?

pub fn print_logo() -> String { println!("{}", banner()) }

I plan on using the banner in other places in the program eventually :)

krisnova · 2022-09-29T00:15:21Z

src/system/init.rs

+
+    mount_vfs("none", "/dev", "devtmpfs");
+    mount_vfs("none", "/sys", "sysfs");
+    mount_vfs("proc", "/proc", "proc");


This sounds a bit crazy, however I have a use case for a system where procfs is NOT mounted.

Is it possible to add a compile time flag or similar to run auraed in an extremely risky experimental mode where procfs is not mounted?

Sure! Will add a simple and fast solution to this PR. Maybe it makes sense to have the mount points configurable? Opened an issue here to discuss and track #25

Maybe a noprocfs kernel parameter?

Ok, I was too optimistic that I can add this fast and simple. Added my comment to the discussion on discord.

I think this requires a second PR

krisnova · 2022-09-29T00:15:45Z

src/system/fileio.rs

@@ -0,0 +1,31 @@
+use std::fs;


krisnova

My suggestion is to go ahead and merge this whenever you feel confident @Vincinator

You should be able to merge now. I will rebase #17 on top of your work, and I encourage you to iterate as you see best. If you would like to pick up more features in subsequent PRs please continue to work however is best for you.

krisnova · 2022-09-29T00:19:19Z

Non blocker however I am wondering about the name system for a module for init. This seems to be overloaded. I am unsure how I feel about it. Does anyone else have any thoughts?

Vincinator · 2022-09-29T06:16:34Z

Non blocker however I am wondering about the name system for a module for init. This seems to be overloaded. I am unsure how I feel about it. Does anyone else have any thoughts?

My vote goes to naming it init. Current scope is just initialization of stuff for the user space.

Vincinator · 2022-09-29T08:46:07Z

@kris-nova this PR is ready to be merged from my point of view
Thanks for your feedback!

krisnova · 2022-09-29T12:01:55Z

Note for myself. Configuration to remove /proc procfs(5) is in this issue: #25

Vincinator added 3 commits September 28, 2022 10:00

fix: make hack makefile targets work with zsh

5de1d83

refactor: fix naming

bc105bd

refactor: do not need libc6 to write files

899055b

cla-bot bot added the Access Granted label Sep 28, 2022

krisnova reviewed Sep 29, 2022

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src/system/init.rs Outdated

@@ -0,0 +1,93 @@

use log::*;

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Can we add the header please?

krisnova reviewed Sep 29, 2022

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src/system/fileio.rs Outdated

@@ -0,0 +1,31 @@

use std::fs;

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Header

krisnova approved these changes Sep 29, 2022

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Vincinator added 2 commits September 29, 2022 08:30

rename system to init

9e3d433

remove empty init

2009531

Vincinator changed the title ~~WIP: mount kernel filesystems if run as pid1~~ mount kernel filesystems if run as pid1 Sep 29, 2022

MalteJ approved these changes Sep 29, 2022

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fix: add apache header

040db27

Vincinator force-pushed the main branch from edee08a to 782b072 Compare September 29, 2022 11:57

Vincinator force-pushed the main branch 2 times, most recently from 6f1de32 to 35ecbc0 Compare September 29, 2022 11:58

add apache headers

12b09a6

Vincinator force-pushed the main branch from 35ecbc0 to 12b09a6 Compare September 29, 2022 11:59

krisnova merged commit e3a871d into aurae-runtime:main Sep 29, 2022

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mount kernel filesystems if run as pid1 #18

mount kernel filesystems if run as pid1 #18

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mount kernel filesystems if run as pid1 #18

mount kernel filesystems if run as pid1 #18

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Vincinator commented Sep 28, 2022

ToDo:

How to test

Links

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