Things will get quite broken if an /etc/passwd entry contains a
colon (which terminates a field), or a newline (which terminates a
record). I know because I just accidentally made a user whose home
directory path contained a newline!
So let's make sure that can't happen.
As the only consequence of isSystemUser is that if the uid is null then
it's allocated below 500, if a user has uid = something below 500 then
we don't require isSystemUser to be set.
Motivation: https://github.com/NixOS/nixpkgs/issues/112647
Since 03eaa48 added perl.withPackages, there is a canonical way to
create a perl interpreter from a list of libraries, for use in script
shebangs or generic build inputs. This method is declarative (what we
are doing is clear), produces short shebangs[1] and needs not to wrap
existing scripts.
Unfortunately there are a few exceptions that I've found:
1. Scripts that are calling perl with the -T switch. This makes perl
ignore PERL5LIB, which is what perl.withPackages is using to inform
the interpreter of the library paths.
2. Perl packages that depends on libraries in their own path. This
is not possible because perl.withPackages works at build time. The
workaround is to add `-I $out/${perl.libPrefix}` to the shebang.
In all other cases I propose to switch to perl.withPackages.
[1]: https://lwn.net/Articles/779997/
This cropped up, because I have a set-up where my work username is
different to my home desktop username, and I am using a parameterized
config for both, so I have something akin to
config.users.users.default-user = ...;
and using
config.users.users.default-user.{name, home}
in certain places to cope with this. Noticed my home-manager bought in
packages (which use the users.users.<name>.packages hence NixOS issue
not home-manager) weren't present.
configuration.nix(1) states
users.extraUsers.<name>.createHome
[...] If [...] the home directory already exists but is not
owned by the user, directory owner and group will be changed to
match the user.
i.e. ownership would change only if the user mismatched; the code
however ignores the owner, it is sufficient to enable `createHome`:
if ($u->{createHome}) {
make_path($u->{home}, { mode => 0700 }) if ! -e $u->{home};
chown $u->{uid}, $u->{gid}, $u->{home};
}
Furthermore, permissions are ignored on already existing directories and
therefore may allow others to read private data eventually.
Given that createHome already acts as switch to not only create but
effectively own the home directory, manage permissions in the same
manner to ensure the intended default and cover all primary attributes.
Avoid yet another configuration option to have administrators make a
clear and simple choice between securely managing home directories
and optionally defering management to own code (taking care of custom
location, ownership, mode, extended attributes, etc.).
While here, simplify and thereby fix misleading documentation.
This attribute is a generalized version of cryptHomeLuks for creating an
entry in /etc/security/pam_mount.conf.xml. It lets the configuration
control all the attributes of the <volume> entry, instead of just the
path. The default path remains the value of cryptHomeLuks, for
compatibility.
This allows disabling users.mutableUsers without configuring any
authentication mechanisms (passwords, authorized SSH keys) other than
Google OS Login.
This is required by (among others) Podman to run containers in rootless mode.
Other distributions such as Fedora and Ubuntu already set up these mappings.
The scheme with a start UID/GID offset starting at 100000 and increasing in 65536 increments is copied from Fedora.
This explanation was contained in the description of
security.initialRootPassword but got lost when it was deprecated
a long ago (f496c3c) and removed.
This option has been deprecated for a long time because is redundant
(users.users.root.initialHashedPassword exists).
Moreover, being of type string, it required to handle the special value
"!" separately, instead of using just `null`.
This explains the
# Allow the user to log in as root without a password.
users.users.root.initialHashedPassword = "";
that the NixOS installer live systems use in
`profiles/installation-device.nix`.
A centralized list for these renames is not good because:
- It breaks disabledModules for modules that have a rename defined
- Adding/removing renames for a module means having to find them in the
central file
- Merge conflicts due to multiple people editing the central file
This change is needed because the order of profiles correlate to the
order in PATH, therefore "/etc/profiles/per-user/$USER" always appeared
after the system packages directories.
I want to manage users centrally via declarativeUsers,
but allow users to change their shell as they please,
similar to how they can change passwords at will
if none of the password-related NixOS settings are set for their user.
With #36556, a check was introduced to make sure the user and group
names do not exceed their respective maximum length. This is in part
because systemd also enforces that length, but only at runtime.
So in general it's a good idea to catch as much as we can during
evaluation time, however the maximum length of the group name was set to
16 characters according groupadd(8).
The maximum length of the group names however is a compile-time option
and even systemd allows more than 16 characters. In the mentioned pull
request (#36556) there was already a report that this has broken
evaluation for people out there.
I have also checked what other distributions are doing and they set the
length to either 31 characters or 32 characters, the latter being more
common.
Unfortunately there is a difference between the maximum length enforced
by the shadow package and systemd, both for user name lengths and group
name lengths. However, systemd enforces both length to have a maximum of
31 characters and I'm not sure if this is intended or just a off-by-one
error in systemd.
Nevertheless, I choose 32 characters simply to bring it in par with the
maximum user name length.
For the NixOS assertion however, I use a maximum length of 31 to make
sure that nobody accidentally creates services that contain group names
that systemd considers invalid because of a length of 32 characters.
Signed-off-by: aszlig <aszlig@nix.build>
Closes: #38548
Cc: @vcunat, @fpletz, @qknight
