On Fri, Dec 13, 2019 at 12:42:02PM +0100, Alex Gladkov wrote:
> From: Alexey Gladkov <legion@altlinux.org>
> 
> The hasher-priv is a SUID utility. This is not good. Separation of the
> server and client parts will allow us to remove SUID flag.
> 
> The separation of server and client is not intended to give clients
> access over the network. This separation is only necessary to distinguish
> privileges. Only UNIX domain socket is used.
> 
> A separate session process is created for each connected user. Each such
> process ends after a certain period of inactivity.

Thank you for trying this idea out; despite the trolling attempts, this
effort is long welcome.

There are some issues with the patchset, which I intend to cover in
subsequent emails. I have published[1] some fix-up commits on top of
these patches in an attempt to ensure that, barring the issues with a
known fix, this works; however, some bugs are definitely still unsolved
by now, so I decided to discuss the more apparent points first.

[1] http://git.altlinux.org/people/arseny/packages/hasher-priv.git?a=summary

There's an issue when hasher-privd tries to fulfill a chrootuid{1,2}
request: the (eventually) unprivileged task executor process
successfully invokes waitpid() or the likes on a child process,
select()s on I/O descriptors, but gets CHLD later — and it looks like
the inherited signal handler causes it to wait again.
I've not yet found a decent reproducer — the following command:
`hsh-shell $workdir'
reproduces the issue reliably for me, but hsh-mkchroot, hsh-rmchroot,
hsh-install are all OK. The root cause nevertheless is not yet
established. It looks like this has to be patched somewhere in
chrootuid(), but I might be wrong on this one.

> 
> Alexey Gladkov (3):
>   Make a daemon from the hasher-priv
>   Add systemd and sysvinit service files
>   Add cgroup support
> 
>  hasher-priv/.gitignore            |   1 +
>  hasher-priv/DESIGN                | 281 +++++++++++++--------
>  hasher-priv/Makefile              |  34 ++-
>  hasher-priv/caller.c              |  81 +++---
>  hasher-priv/caller_server.c       | 373 ++++++++++++++++++++++++++++
>  hasher-priv/caller_task.c         | 217 +++++++++++++++++
>  hasher-priv/cgroup.c              | 119 +++++++++
>  hasher-priv/cmdline.c             |  27 +-
>  hasher-priv/communication.c       | 392 ++++++++++++++++++++++++++++++
>  hasher-priv/communication.h       |  77 ++++++
>  hasher-priv/config.c              | 148 ++++++++++-
>  hasher-priv/epoll.c               |  39 +++
>  hasher-priv/epoll.h               |  18 ++
>  hasher-priv/hasher-priv.c         |  78 ++++++
>  hasher-priv/hasher-privd.c        | 375 ++++++++++++++++++++++++++++
>  hasher-priv/hasher-privd.service  |  11 +
>  hasher-priv/hasher-privd.sysvinit |  86 +++++++
>  hasher-priv/io_log.c              |   2 +-
>  hasher-priv/io_x11.c              |   2 +-
>  hasher-priv/killuid.c             |   2 +-
>  hasher-priv/logging.c             |  64 +++++
>  hasher-priv/logging.h             |  55 +++++
>  hasher-priv/main.c                |  75 ------
>  hasher-priv/pass.c                | 117 ++++++++-
>  hasher-priv/pidfile.c             | 128 ++++++++++
>  hasher-priv/pidfile.h             |  44 ++++
>  hasher-priv/priv.h                |  35 ++-
>  hasher-priv/server.conf           |  22 ++
>  hasher-priv/sockets.c             | 183 ++++++++++++++
>  hasher-priv/sockets.h             |  32 +++
>  hasher-priv/x11.c                 |   1 +
>  31 files changed, 2872 insertions(+), 247 deletions(-)
>  create mode 100644 hasher-priv/caller_server.c
>  create mode 100644 hasher-priv/caller_task.c
>  create mode 100644 hasher-priv/cgroup.c
>  create mode 100644 hasher-priv/communication.c
>  create mode 100644 hasher-priv/communication.h
>  create mode 100644 hasher-priv/epoll.c
>  create mode 100644 hasher-priv/epoll.h
>  create mode 100644 hasher-priv/hasher-priv.c
>  create mode 100644 hasher-priv/hasher-privd.c
>  create mode 100644 hasher-priv/hasher-privd.service
>  create mode 100755 hasher-priv/hasher-privd.sysvinit
>  create mode 100644 hasher-priv/logging.c
>  create mode 100644 hasher-priv/logging.h
>  delete mode 100644 hasher-priv/main.c
>  create mode 100644 hasher-priv/pidfile.c
>  create mode 100644 hasher-priv/pidfile.h
>  create mode 100644 hasher-priv/server.conf
>  create mode 100644 hasher-priv/sockets.c
>  create mode 100644 hasher-priv/sockets.h
>