[pve-devel] [RFC container v2 2/3] setup: base: remove existing ssh host keys

From: Daniel Kral <d.kral@proxmox.com>
To: pve-devel@lists.proxmox.com
Subject: [pve-devel] [RFC container v2 2/3] setup: base: remove existing ssh host keys
Date: Fri,  4 Jul 2025 20:23:35 +0200	[thread overview]
Message-ID: <20250704182336.469274-2-d.kral@proxmox.com> (raw)
In-Reply-To: <20250704182336.469274-1-d.kral@proxmox.com>

Remove existing SSH host keys after container creation to prevent
multiple containers sharing the same SSH host keys, especially those
which are not overwritten/generated by rewrite_ssh_host_keys() later.

This is called in the Base's post_create_hook(...) to prevent unwanted
removal for certain types of containers, e.g., unmanaged containers.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
---
Because of the HA Rules stuff, I unfortunately didn't get the time to
properly test these with any container images, but wanted to send them
anyway.

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

diff --git a/src/PVE/LXC/Setup/Base.pm b/src/PVE/LXC/Setup/Base.pm
index dbfc775..ea6f598 100644
--- a/src/PVE/LXC/Setup/Base.pm
+++ b/src/PVE/LXC/Setup/Base.pm
@@ -466,6 +466,30 @@ sub set_user_password {
     }
 }
 
+sub remove_existing_ssh_host_keys {
+    my ($self) = @_;
+
+    my $ssh_rootdir = "$self->{rootdir}/etc/ssh";
+
+    return if !-d $ssh_rootdir;
+
+    PVE::Tools::dir_glob_foreach(
+        $ssh_rootdir,
+        qr/ssh_host_.*/,
+        sub {
+            my ($key_filename) = @_;
+
+            next if $self->ct_is_file_ignored($key_filename);
+
+            print "Remove existing ssh host key '$key_filename' ...\n";
+
+            $self->protected_call(sub {
+                $self->ct_unlink($key_filename);
+            });
+        },
+    );
+}
+
 my $parse_home_dir = sub {
     my ($self, $passwdfile, $user) = @_;
 
@@ -687,6 +711,7 @@ sub post_create_hook {
     &$randomize_crontab($self, $conf);
 
     $self->set_user_password($conf, 'root', $root_password);
+    $self->remove_existing_ssh_host_keys();
     $self->set_user_authorized_ssh_keys($conf, 'root', $ssh_keys) if $ssh_keys;
     $self->setup_init($conf);
     $self->setup_network($conf);
-- 
2.39.5



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