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nixos.users-groups: Set up subuid/subgid mappings for all normal users

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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 commit is contained in:
adisbladis
2020-07-13 13:15:02 +02:00
parent 0963cebfc5
commit 5733967290
4 changed files with 66 additions and 54 deletions
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nixos/modules/config/update-users-groups.pl
+55
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@@ -281,3 +281,58 @@ foreach my $u (values %usersOut) {
}
updateFile("/etc/shadow", \@shadowNew, 0600);
# Rewrite /etc/subuid & /etc/subgid to include default container mappings
my $subUidMapFile = "/var/lib/nixos/auto-subuid-map";
my $subUidMap = -e $subUidMapFile ? decode_json(read_file($subUidMapFile)) : {};
my (%subUidsUsed, %subUidsPrevUsed);
$subUidsPrevUsed{$_} = 1 foreach values %{$subUidMap};
sub allocSubUid {
my ($name, @rest) = @_;
# TODO: No upper bounds?
my ($min, $max, $up) = (100000, 100000 * 100, 1);
my $prevId = $subUidMap->{$name};
if (defined $prevId && !defined $subUidsUsed{$prevId}) {
$subUidsUsed{$prevId} = 1;
return $prevId;
}
my $id = allocId(\%subUidsUsed, \%subUidsPrevUsed, $min, $max, $up, sub { my ($uid) = @_; getpwuid($uid) });
my $offset = $id - 100000;
my $count = $offset * 65536;
my $subordinate = 100000 + $count;
return $subordinate;
}
my @subGids;
my @subUids;
foreach my $u (values %usersOut) {
my $name = $u->{name};
foreach my $range (@{$u->{subUidRanges}}) {
my $value = join(":", ($name, $range->{startUid}, $range->{count}));
push @subUids, $value;
}
foreach my $range (@{$u->{subGidRanges}}) {
my $value = join(":", ($name, $range->{startGid}, $range->{count}));
push @subGids, $value;
}
if($u->{isNormalUser}) {
my $subordinate = allocSubUid($name);
$subUidMap->{$name} = $subordinate;
my $value = join(":", ($name, $subordinate, 65536));
push @subUids, $value;
push @subGids, $value;
}
}
updateFile("/etc/subuid", join("\n", @subUids) . "\n");
updateFile("/etc/subgid", join("\n", @subGids) . "\n");
updateFile($subUidMapFile, encode_json($subUidMap) . "\n");