A call is parked until the resolver says who sent it, and an outbound
call sits in a pending slot until its reply lands. Neither had a way
to give up. A broker that answers GetConnectionUnixUser slowly, or
not at all, leaves the caller waiting forever and keeps the slot; four
of those and every later privileged call is refused with
LimitsExceeded until Finit restarts.
libink cannot time itself out, it has no event loop, so the deadline
is the embedder's to keep. One sweep per connection covers both, and
the ordering between them stays in the library rather than in each
embedder: calls first, because one timing out usually resolves the
park it was made for, and AccessDenied tells that caller more than a
bare timeout.
The sweep is armed when a resolve is deferred and stops rearming as
soon as nothing is outstanding, so a system that never meets a broker
never wakes up for it.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Parked calls and outbound calls awaiting a reply only ever happen on a
connection talking to a broker, but the parked array sat on the server
and the pending array on every connection. A server with no broker
carried 4 KiB of slots it could never fill, and both were reachable
from code paths that have no business in them.
Move both behind one struct, allocated on the first park or call and
freed with the connection. link_server_t goes from 4400 to 168 bytes;
link_connection_t barely moves, its buffers dominate, but an ordinary
peer no longer carries reply-tracking it never uses.
Tokens are now per bus rather than per server, so link_uid_resolved()
takes the connection the answer is about. Every resolver already has
it: it is the first argument to both the resolver and the reply
callback.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
The legacy socket logs a line per command under initctl debug; the bus
logged nothing, so the transport that now carries most of initctl was
the one you could not watch.
libink gets a logger hook rather than a dependency on Finit's: it
passes the emitting function and a formatted message, and dbus.c hands
both to logit() so the two sources read alike. Trace points cover the
connection lifecycle, every inbound call, and why a call was refused.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
On the local bus SO_PEERCRED says who is calling and the kernel is the
one saying it. Behind a broker one connection carries every caller,
so that credential describes dbus-daemon and nothing else, and every
privileged method was refused there, root included.
Ask the bus driver instead. libink parks the call and hands us the
sender; we ask GetConnectionUnixUser and answer when the reply lands,
through the same event loop as everything else. Nothing blocks:
blocking in PID 1 is why libuEv exists. That needs calls libink can
make on a connection it already has, so it gained those too.
Answers are cached, since a bus never reuses a unique name while it
runs. Not across a restart though: a new dbus-daemon numbers from
scratch and :1.7 becomes somebody else, so the cache goes when the
broker does. A sender name too long to key on is refused rather than
truncated, two callers sharing a truncated key would share an
identity.
Privilege is no longer uid 0 alone. The socket is already owned by
the --with-group group, so refusing its members every method that
changes anything left a wheel user able to open the bus and unable to
reboot. Both gates now say the same thing.
Group membership needs NSS, which the C library loads with dlopen(),
so the lookup is compiled out where Finit is built to link statically.
That leaves such a build root-only, which is worth saying out loud
rather than leaving to be discovered.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
libink was written peer to peer, where one connection is one client
and one principal. Attaching to a message bus breaks both halves of
that, and two things followed from it.
Signals never reached the system bus. Fan-out is gated on the peer
having sent AddMatch, but a broker subscribes for its own clients and
never sends us one, so every ServiceStateChanged was dropped on the
floor. A connection attached with LINK_ATTACH_BROKER gets them all.
Hello, AddMatch and RemoveMatch write per-connection state. Shared by
every caller behind a broker, that lets one sender exhaust the match
cap or drop another's rule, so we leave all three to the bus, whose
job they are.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
The summary table, the per-service detail, JSON and the quiet and
ident forms all read state Finit already publishes, so they read it
from the bus like everything else rather than through a second path
that has to be kept in step.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Runlevel and version are state, not actions, so they belong behind
org.freedesktop.DBus.Properties rather than another method each.
Finit also claims org.finit on the system bus when it finds one, so
ordinary D-Bus clients can reach it without knowing about
/run/finit/bus. Opportunistic on purpose: no dbus-daemon is a normal
state for the systems Finit runs on, not an error to report.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Finit had no way to answer the question every service manager gets
asked: what is running, and change it. D-Bus is how the rest of
userspace asks, but linking libdbus, sd-bus or GIO into PID 1 buys a
dependency, an allocator and a main loop we do not control.
So libink: the wire format, an object tree, and a bus of Finit's own
at /run/finit/bus, gated like INIT_SOCKET. It speaks the standard
org.freedesktop.DBus, .Peer, .Introspectable interfaces, and Finit's
own Manager1, Service1 and Cond1 on top. Methods that change
something are marked privileged and answered only for a caller the
kernel vouched for, via SO_PEERCRED.
Server and client both, since initctl is the first thing that needs
to talk to it, and its Start/Stop/Restart/Reload now go over the bus
rather than the legacy socket.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
Joachim Wiberg