[9fans] backwards-incompatible changes

["Russ Cox" <rsc@plan9.bell-labs.com>]

There are two backwards incompatible changes
that will appear on sources tomorrow.  If you prepare
for them, nothing will break when you do the pull.

First, namespace files now have a `.' syntax to include
other files.  /lib/namespace will include /lib/namespace.$sysname.
Thus, namespace.$sysname will become additions to the
default name space rather than replacing it.  To prepare for
this change, add the line ``clear'' to the top of any
namespace.$sysname files you have.  The old code
will ignore it, and the new code will do rfork(RFCNAMEG)
when it sees it.  Once you are running the new code
everywhere, you can trim your namespace.$sysname
files considerably.

Second, the handling of rsa keys is redone.  The new
tools are already out -- see rsa(8).  

There will be a new ssh client that looks for keys
identified by 

	proto=rsa service=ssh

rather than

	proto=sshrsa

If you put both tags on the key, that will work with
either ssh.  Once you've switched, you can remove
the proto=sshrsa tag.

There will be a new sshserve that uses factotum
to hold the host key, identified by

	proto=rsa service=sshserve

You can convert with

	awk '{
		printf("key proto=rsa service=sshserve owner=* ");
		printf("size=%s ek=%s !dk=%s n=%s !p=%s !q=%s !kp=%s !kq=%s !c2=%s\n",
			$1, $2, $3, $4, $5, $6, $7, $8, $9);
	}' /sys/lib/ssh/hostkey.secret

After the switch you can delete hostkey.secret.

TLS will look for keys identified by

	proto=rsa service=tls

rather than

	proto=sshrsa

As with the ssh client, if you put both tags on the key,
it will work with old and new.

Also, and not an incompatibility, there is a new factotum
that knows about an ``owner'' tag to specify who can use
the key.  owner=* means anyone, otherwise you give
a list owner=rsc owner=presotto etc.  This way, you can
publish, in bootes's factotum, the SSH host key and
TLS key, and then services using them can run as none.

Summary:

	- add "clear" to the top of your namespace.$sysname files
	- add "proto=rsa service=ssh" to your ssh client keys
	- add your ssh host key to factotum
	- add "proto=rsa service=tls" to your tls server keys

Russ