Some services require GUI access. Make qrexec-agent handling this, based
on per-service configuration, instead of forcing every caller to call
qubes.WaitForSession service first. This is especially important for
Disposable VMs, because those are destroyed after a single service call.
This needs to be done in qrexec-agent (instead of service script, or
qubes-rpc-multiplexer), because agent will behave differently depending
on GUI session being available or not. Namely, will use
qrexec-fork-server (so the process will be a child of session leader),
or will open new session.
Service configuration lives in /etc/qubes/rpc-config/SERVICE_NAME, can
can contain 'key=value' entries (no space around '=' allowed). Currently
the only settings supported is 'wait-for-session', with value either '0'
or '1'.
QubesOS/qubes-issues#2974
Prepend "-" to shell name, to instruct it being a login shell. This way
shell will initialize environment, load /etc/profile etc.
FixesQubesOS/qubes-issues#2903
Instead of calling 'su' to switch the user, use own implementation of
this. Thanks to PAM it's pretty simple. The main reason is to have
control over process waiting for session termination (to call
pam_close_sesion/pam_end). Especially we don't want it to keep std* fds
open, which would prevent qrexec-agent from receiving EOF when one of
them will be closed.
Also, this will preserve QREXEC_AGENT_PID environment variable.
FixesQubesOS/qubes-issues#2851
Simply forget about that connection, instead of waiting for further
messages. If that connection is no longer available, select would return
EBADF, which would cause qrexec-agent termination.
This way qrexec-client-vm will have much more information, at least:
- will know whether the service call was accepted or refused
- potentially will know remote process exit code
This commit implements the first point - the local process will not be
started if service call was refused.
This process should be started from user session (most likely
qubes-session). New processes (of that user) will be created as
children of that session making logind and such crap happy. This should
also solve problems with EOF transmission (no additional "su" process)
and prevent loading all the environment multiple times.
Move (qrexec-agent version of) do_exec to qrexec-agent.c, move
handle_handshake to qrexec-agent-data.c (common to all agent binaries).
Fix indentation (tabs -> spaces).
