grantseltzer / karn Goto Github PK

Run unit tests, have a github hook, all that jazz

This is currently breaking the build, woops

Default action should take the same precedence as normal seccomp rules.

It may be particularly useful if there was a 'notes' field in the declarations so they can be interacted with as opposed to just TOML comments.

For example:

• There's a declaration for using removable storage devices. However, they need to be mounted. The declaration uses /mnt but it's possible to mount devices elsewhere. The 'notes' field may say "You need to use /mnt or edit the declaration to your custom location".

Functionality can then be built into the generate command to display notes as computation is done.

There needs to be a package for validating individual values, as well as a full spec. The package should be consumed internally at all input points, as well as a small CLI tool

This means checking actual values for:

• Directory paths
• Capabilities
• Syscalls
• ...

For example, if not seccomp action default is specified, make it errno.

This includes creating ~/.karn/declarations and placing official ones there

Also should have a --no-defaults flag to not include them

Seccomp default

Apparmor default

The declaration definition should be changed to this (in spec.go):

// Declaration holds all the data from karn declaration files
type Declaration struct {
	SystemCalls  SystemCalls  `toml:"System-Calls,omitempty"`
	Capabilities Capabilities `toml:"Capabilities,omitempty"`
	Filesystem   FileSystem   `toml:"Filesystem,omitempty"`
	Network      Network      `toml:"Network,omitempty"`
	System       System       `toml:"System,omitempty"`
	Includes     []string     `toml:"Includes,omitempty"` 
}

This allows for filling in overlap with the varying levels of entitlements. For example, a declaration that grants access to reading/writing from removable devices will need the filesystem declaration as well as access to the particular socket paths. Instead of copying the filesystem fields into the new one, you can just specify "filesystem" in the Includes field.

There's some challenge to this, i.e. making sure there aren't duplicate rules specified and solving for circular includes.

karn entitlements would work.

gobindata is a tool for embedding data into a binary. This is perfect for shipping karn as one static binary with all the entitlement declarations bundled inside.

I haven't fully researched go-bindata's interface but this might be best handled by adding a make target to handle it. Here's an example of a project doing it this way.

The unit tests in generate are missing an import for "github.com/grantseltzer/karn/tests" which is used for the type 'MockWriter'

i.e. "non-network app", "non-exec-filesys", "read-only"

The default docker seccomp has a lot of these relationships, will be useful resource.

Example:

...
			"names": [
				"bpf",
				"clone",
				"fanotify_init",
				"lookup_dcookie",
				"mount",
				"name_to_handle_at",
				"perf_event_open",
				"quotactl",
				"setdomainname",
				"sethostname",
				"setns",
				"umount",
				"umount2",
				"unshare"
			],
			"action": "SCMP_ACT_ALLOW",
			"args": [],
			"comment": "",
			"includes": {
				"caps": [
					"CAP_SYS_ADMIN"
				]
			},
			"excludes": {}
		}
...

If one declarations specifies to kill clone and another says to errno clone, only one rule should be added (in this case, kill). Instead these are appended. Basically this needs to be implemented.

See the clashing-rules subtest

https://asciinema.org/