But with one key difference: it’s *not* in fact SUID. Instead it just asks the service manager to invoke a command or shell under the target user’s UID. It allocates a new PTY for that, and then shovels data back and forth from the originating TTY and this PTY. Or in other words: the target command is invoked in an isolated exec context, freshly forked off PID 1, without inheriting any context from the client (well, admittedly, we *do* propagate $TERM, but that’s an explicit exception, i.e. allowlist rather than denylist).
Unfortunately, this is about as easy as it gets. Practically though, it isn’t going to matter. It sounds like run0 will be a drop-in replacement for sudo. We will know for sure in about 3 days (at the rate at which they assimilate features).
While it may be true that getting rid of SUID binary is ideal, widening systemd’s security surface area is much more concerning to me than the sudo binary.
I would fucking hope not. TERM is explicitly passed along as the only exception, which is the only sensible default for temporary privilege elevation in a shell.
Sudo also blocks almost all environment variables, with the option to set or copy them on demand. I assume that run0 will have similar facilities to propagate variables on demand.
PS: This is my technical understanding. Personally, I don’t like systemd eating up all the other utilities.
I understood some of those words…
Unfortunately, this is about as easy as it gets. Practically though, it isn’t going to matter. It sounds like
run0will be a drop-in replacement forsudo. We will know for sure in about 3 days (at the rate at which they assimilate features).So there would be no practical benefits of switching?
It gets rid of one more SUID binary. That’s always a win for security.
Sudo probably is way more comfortable to use and has way more configurable, too – that usually does not help to make a tool secure either:-)
While it may be true that getting rid of SUID binary is ideal, widening systemd’s security surface area is much more concerning to me than the sudo binary.
This has already been possible, the patch modifying
run.cto be able to do this is not even 400 lines long and was mostly just exposing its feature in a different way. (the entire patch was <1.5k lines, with most being docs, tests and a bit of plumbing for the colored terminal)So none of my environment variables come with? 😐
I would fucking hope not. TERM is explicitly passed along as the only exception, which is the only sensible default for temporary privilege elevation in a shell.
Sudo also blocks almost all environment variables, with the option to set or copy them on demand. I assume that
run0will have similar facilities to propagate variables on demand.PS: This is my technical understanding. Personally, I don’t like systemd eating up all the other utilities.