[pve-devel] [PATCH container] fix #3960: properly set owner in CT setup

[Fabian Grünbichler]

there were two helpers that were not handling this correctly:

ct_make_path

since this never gets called with $opts, and there also is no 'owner'
and 'group' in $self, the previous logic could never work, sometimes
leaving nobody:nogroup files around for unprivileged containers.

since only the centos and suse plugins use this helper, the issue was
fairly limited.

ct_symlink

could create symlinks owned by nobody:nogroup. since symlinks are
created 777 by default, this just meant they were not modifiable inside
the container, but reading/dereferencing was no problem so it went
unnoticed so far.

Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
---

Notes:
    instead of POSIX::lchown we could also expose AT_SYMLINK_NOFOLLOW in PVE::Tools
    and call fchownat with that, but it would require a versioned dep bump..

 src/PVE/LXC/Setup/Base.pm | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/PVE/LXC/Setup/Base.pm b/src/PVE/LXC/Setup/Base.pm
index dafd69a..7c93dfb 100644
--- a/src/PVE/LXC/Setup/Base.pm
+++ b/src/PVE/LXC/Setup/Base.pm
@@ -12,6 +12,7 @@ use Fcntl;
 use File::Path;
 use File::Spec;
 use File::Basename;
+use POSIX ();
 
 use PVE::INotify;
 use PVE::Tools;
@@ -663,22 +664,26 @@ sub ct_open_file_write {
 
 sub ct_make_path {
     my $self = shift;
-    if ($self->{id_map}) {
-	my $opts = pop;
-	if (ref($opts) eq 'HASH') {
-	    $opts->{owner} = $self->{rootuid} if !defined($self->{owner});
-	    $opts->{group} = $self->{rootgid} if !defined($self->{group});
-	}
-	File::Path::make_path(@_, $opts);
-    } else {
-	File::Path::make_path(@_);
+
+    my $opts = {};
+    if (defined($self->{id_map})) {
+	$opts->{owner} = $self->{rootuid};
+	$opts->{group} = $self->{rootgid};
     }
+    File::Path::make_path(@_, $opts);
 }
 
 sub ct_symlink {
     my ($self, $old, $new) = @_;
     return if $self->ct_is_file_ignored($new);
-    return CORE::symlink($old, $new);
+    if (CORE::symlink($old, $new)) {
+	if (defined($self->{id_map})) {
+	    POSIX::lchown($self->{rootuid}, $self->{rootgid}, $new);
+	}
+	return 1;
+    } else {
+	return 0;
+    }
 }
 
 sub ct_readlink {
-- 
2.30.2