Since service_add_fd_store() already does the check, remove the redundant check
from service_add_fd_store_set().
Also, print a warning when repopulating FDStore after daemon-reexec and we hit
the limit. This is a user visible issue, so we should not discard fds silently.
(Note that service_deserialize_item is impacted by the return value from
service_add_fd_store(), but we rely on the general error message, so the caller
does not need to be modified, and does not show up in the diff.)
If execve() or socket() is filtered the service manager might get into trouble
executing the service binary, or handling any failures when this fails. Mention
this in the documentation.
The other option would be to implicitly whitelist all system calls that are
required for these codepaths. However, that appears less than desirable as this
would mean socket() and many related calls have to be whitelisted
unconditionally. As writing system call filters requires a certain level of
expertise anyway it sounds like the better option to simply document these
issues and suggest that the user disables system call filters in the service
temporarily in order to debug any such failures.
See: #3993.
Seccomp is generally an unprivileged operation, changing security contexts is
most likely associated with some form of policy. Moreover, while seccomp may
influence our own flow of code quite a bit (much more than the security context
change) make sure to apply the seccomp filters immediately before executing the
binary to invoke.
This also moves enforcement of NNP after the security context change, so that
NNP cannot affect it anymore. (However, the security policy now has to permit
the NNP change).
This change has a good chance of breaking current SELinux/AA/SMACK setups, because
the policy might not expect this change of behaviour. However, it's technically
the better choice I think and should hence be applied.
Fixes: #3993
@resources contains various syscalls that alter resource limits and memory and
scheduling parameters of processes. As such they are good candidates to block
for most services.
@basic-io contains a number of basic syscalls for I/O, similar to the list
seccomp v1 permitted but slightly more complete. It should be useful for
building basic whitelisting for minimal sandboxes
The system call is already part in @default hence implicitly allowed anyway.
Also, if it is actually blocked then systemd couldn't execute the service in
question anymore, since the application of seccomp is immediately followed by
it.
Switch drivers uses phys_port_name attribute to pass front panel port
name to user. Use it to generate netdev names.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
We would close all the stored fds in service_release_resources(), which of
course broke the whole concept of storing fds over service restart.
Fixes#4408.
This makes applying groups after applying the working directory, this
may allow some flexibility but at same it is not a big deal since we
don't execute or do anything between applying working directory and
droping groups.
Rewrite the function to be slightly simpler. In particular, if a specific
match is found (like ConditionVirtualization=yes), simply return an answer
immediately, instead of relying that "yes" will not be matched by any of
the virtualization names below.
No functional change.
Various things don't work when we're running in a user namespace, but it's
pretty hard to reliably detect if that is true.
A function is added which looks at /proc/self/uid_map and returns false
if the default "0 0 UINT32_MAX" is found, and true if it finds anything else.
This misses the case where an 1:1 mapping with the full range was used, but
I don't know how to distinguish this case.
'systemd-detect-virt --private-users' is very similar to
'systemd-detect-virt --chroot', but we check for a user namespace instead.
