Currently nstool die()s on essentially any error. In most cases that's
fine for our purposes. However, it's a problem when in "hold" mode and
getting an IO error on an accept()ed socket. This could just indicate that
the control client aborted prematurely, in which case we don't want to
kill of the namespace we're holding.
Adjust these to print an error, close() the control client socket and
carry on. In addition, we need to explicitly ignore SIGPIPE in order not
to be killed by an abruptly closed client connection.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
nstool in "exec" mode will propagate some signals (specifically SIGTERM) to
the process in the namespace it executes. The signal handler which
accomplishes this is called simply sig_handler(). However, it turns out
we're going to need some other signal handlers, so rename this to the more
specific sig_propagate().
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Particularly in shell it's sometimes natural to save the pid from a process
run and later kill it. If doing this with nstool exec, however, it will
kill nstool itself, not the program it is running, which isn't usually what
you want or expect.
Address this by having nstool propagate SIGTERM to its child process. It
may make sense to propagate some other signals, but some introduce extra
complications, so we'll worry about them when and if it seems useful.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
nstool loops on accept(), but failed to close the accepted socket fds
before continuing on. So, with repeated commands it would eventually die
with an EMFILE.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Normal filesystem paths can be very long (PATH_MAX is around 8k), however
Unix domain sockets can only use relatively short paths (UNIX_PATH_MAX is
108 on Linux). Currently nstool will simply truncate paths that are too
long, leading to difficult to understand failures.
Make such failures clearer, with an explicit error message if given a path
that's too long.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
If we enter a mount namespace with nstool exec our working directory will
be changed to / in the new mount ns. This is surprising if we haven't
actually altered any mounts yet in the new ns. Instead, change the working
directory to match that of the holder process in this situation.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This is possible useful in nstool info and has further uses for nstool
exec.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This allows you to run commands within a user namespace with the
privilege that comes from owning that userns.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This combines nstool info -pw <sock> with nsenter with various options for
a more convenient and less verbose of entering existing nstool managed
namespaces.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Will make things a bit less verbose in future.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
So that we'll probably give a better error if you point it at something
that's not an nstool hold control socket.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Give nstool the ability to detect what namespaces the target process is in,
relative to where it's called. That is, those namespace types for which
the target is not in the same namespace as the caller. For now, just
print this information with "info", which can be useful for debugging.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
The new subcommand gives more information about the holder process and its
namespace, and may be further extended in future. Add some options which
give the old behaviour for existing scripts.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This will make it easier to differentiate the options to those commands
further in future.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Having the "subcommand" first is more conventional and will make it more
natural for future extensions I have planned.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
In preparation for extending what it does.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
