rtsold: Extend casper to support various interface operations

[markj]

Summary

I recently changed the kernel to disallow network interface ioctls when
in capability mode. I overlooked the fact that rtsold may periodically
attempt to bring up an interface and fetch link info. This change
extends the cap_llflags service to support the required operations, and
renames the service to cap_if.

[markj]

I plan to rename cap_llflags.c to cap_if.c, but didn't do that in this review since otherwise git diff shows cap_if.c as a newly added file.

[markj]

Fix command name.

[bapt]

after this change rtsold does not complain anymore on an ioctl now allowed in capmode, but now rtsol is stuck on kread blocking the netif service I had to ctrl-c it to have it working

[markj]

Correct the casper command name used in cap_llflags_get().

[markj]

In D29824#669436, @bapt wrote:

after this change rtsold does not complain anymore on an ioctl now allowed in capmode, but now rtsol is stuck on kread blocking the netif service I had to ctrl-c it to have it working

Thanks, the latest update should fix it.

[bz]

I have not reviewed; I can only say the error is gone when I apply the latest change and rtsol seems to be running fine.

[oshogbo]

In general it's a great work.
Minor requests.

usr.sbin/rtsold/cap_llflags.c

72

New line?

321

Maybe to simplify code we can do:

return (return_errno(ifmedia_get(ifname, ifmr)));

And in the` if_command`:

error = fflags_get(ifname, &flags);
if (error != 0)
	nvlist_add_number(nvlout, "flags", flags);

or I'm not sure if this actually would simplify it.

342

I like this pattern.

376

New line?

usr.sbin/rtsold/rtsold.c

259

Can't you pass argc and just do nvlist_add_string_array ? This would limit memory shuffling.

[emaste]

usr.sbin/rtsold/cap_llflags.c

72

style(9) doesn't demand it anymore

[oshogbo]

usr.sbin/rtsold/cap_llflags.c

72

Oh I didn't notice that this has changed. Thanks!

[bz]

What's the status on this? Is it currently needed in HEAD? If the other bits might be fixed in HEAD (for now) will this still go in? I have it in a dev-tree and just wonder if I should keep it or ditch it?

[markj]

In D29824#683732, @bz wrote:

What's the status on this? Is it currently needed in HEAD? If the other bits might be fixed in HEAD (for now) will this still go in? I have it in a dev-tree and just wonder if I should keep it or ditch it?

It is not needed anymore, as I reverted part of the kernel commit which necessitates this change. So it should be ok to drop it.

I am not sure whether to go ahead with this patch. It's probably still a good idea to move network configuration into a casper process.