Incorporate the OpenSMTPD' privsep crypto engine. The idea behind
it is to never load the certificate' private keys in a networked
process, instead they are loaded in a separate process (the `crypto'
one) which signs payloads on the behalf of the server processes.
This way, we greatly reduce the risk of leaking the certificate'
private key should the server process be compromised.
This currently compiles only on LibreSSL (portable fix is in the
way).
We don't always do privilege dropping (as we may start as unprivileged
user), so set these two beforehand so when we skip privdrop we don't
miss to set privsep_process and set the process' title.
avoids issues since the same file is sent to multiple processes
after being dup()'ed. Since these files are meant to be regular
files, I don't expect short reads.
Don't have all the processes read gmid.conf. The parent needs to do
that, and the will send the config to the children (already
happening.) The other processes were reading the config anyway to
figure out the user and the chroot (if enabled); make the parent pass
additional flag to propagate that info.
We dissociate a bit from the "usual" proc.c but it's a change worth
having.
Was temporarly disabled during the transition to real privsep.
While here, fix a memory leak when using `require client ca'.
Also, avoid leaking info about the parent address space layout to
server processes by not sending pointer values.
server_configure_done is the code we ran in IMSG_RECONF_END splitted
in a separate functions.
This is all needed for ge.c which doesn't do privsep but needs to
bootstrap the server process.
it's better than the previous Makefile.depend approach since this
automatically adapts to the included headers without requiring
manual intervention to regen the list.
It uses the 'common' proc.c from various OpenBSD-daemons.
gmid grew organically bit by bit and it was also the first place where I
tried to implement privsep. It wasn't done very well, in fact the
parent process (that retains root privileges) just fork()s a generation
of servers, all sharing *exactly* the same address space. No good!
Now, we fork() and re-exec() ourselves, so that each process has a fresh
address space.
Some features (require client ca for example) are temporarly disabled,
will be fixed in subsequent commits. The "ge" program is also
temporarly disabled as it needs tweaks to do privsep too.