gstfsd, the root service on each compute that rewrites a shut-off VM's
/etc/shadow and authorized_keys, did what any client on its port asked.
Now it needs GSTFSD_KEY (64 hexadecimal characters, in the unit's
/etc/default/webvirt-gstfsd) and does not start without it. Each
connection gets a new challenge; the panel signs its request for it
with HMAC-SHA256 and gstfsd checks the signature before any change, so
a request recorded on one connection is refused on another. gstfsd
signs its reply for the same challenge and the panel's nonce, and the
panel accepts only that reply.
Each compute has a gstfsd key, the host's GSTFSD_KEY: the compute forms
and the API take it and never show it, and an empty value on an edit
keeps it. The bootstrap script makes the key file once, readable by
root only; the README shows how to make it and where the panel takes
it. The traffic is still not encrypted: a remote panel's port stays
open to the panel's address only.
A compute's hostname and login go unquoted into the libvirt connection URI
(qemu+ssh://login@host/system, qemu+tcp://host/system, qemu+tls://...) and,
for an SSH compute, into the ssh command line of the DRBD status view. They
were barely validated: validate_hostname used re.match with a negated class,
so it caught only a leading special character, and login was never checked.
A hostname like "192.0.2.1/system?command=/path" injected a libvirt URI
parameter (verified: connecting ran the named command through the ssh
wrapper), and TLS/SSH parameters such as no_verify, pkipath, socket or
netcat could be added the same way; a login like "-oProxyCommand=..." became
an ssh option. The DRF ComputeSerializer applied neither check, and
validate_name tested a string literal instead of its argument, so it never
raised.
validate_hostname now accepts only an IPv4 address or a host name with
fullmatch (no scheme, port, path, query, whitespace or IPv6 literal; IPv6 is
left out until the URI building brackets it). validate_login accepts an empty
value (TCP falls back to the server's authentication, the socket transport
ignores the login) or a plain name with no leading "-". Both sit on the
Compute model fields, so the forms and the DRF serializer (which copies model
validators onto its fields) reject the values; a migration records the
metadata. validate_name checks its argument. drbd_status validates the login
and hostname before building login@host and ends ssh option parsing with
"--"; an existing or bypassed bad row is skipped rather than run.
Tests: hostname/login validators accept real values and reject URI and
option injection; the SSH form and the serializer (create, and an empty TCP
login) enforce them; drbd_status skips an injecting target. Checked the real
test computes still validate. The new tests fail on the previous code.
Migration is client-driven: libvirt sends the VM's memory to the
destination's own host name unless a migration URI is given, and the
app never gave one. Where the hosts cannot resolve each other's names
(or the names point at a management network) every migration failed
with "Unable to resolve address '<host name>' service '49152'".
A compute now has an optional migration address (an IP address or a
host name, no scheme or port), editable in the compute form and the
API. A VM migrating to that compute is sent to tcp://<address>
(bracketed for IPv6). Empty, the default for existing computes, keeps
the previous behavior. The compute's host name is not reused, because
for SSH computes it can be an ssh_config alias.
The migration log entry names the address when one is set.
