[PATCH pmg-api 1/2] pam/pmg realm: use yescrypt for new password hashes

[Shannon Sterz <s.sterz@proxmox.com>]

and in the case of the pmg realm, update old stored hashes on
authentication. this should improve the security of passwords.
yescrypt is the default in Debian since the Bullseye release [1].

[1]: Section 5.1.4,
https://www.debian.org/releases/bullseye/amd64/release-notes.en.txt

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>
---

Notes:
    note that the change for pam also means that previously if a new
    password for a pam user was set via the PVE API, the hash function
    used for that password would effectively have been downgraded.

 src/PMG/API2/Users.pm    | 2 +-
 src/PMG/AccessControl.pm | 2 +-
 src/PMG/UserConfig.pm    | 9 ++++++++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/src/PMG/API2/Users.pm b/src/PMG/API2/Users.pm
index e638ae8..a973653 100644
--- a/src/PMG/API2/Users.pm
+++ b/src/PMG/API2/Users.pm
@@ -118,7 +118,7 @@ __PACKAGE__->register_method({
             foreach my $k (keys %$param) {
                 my $v = $param->{$k};
                 if ($k eq 'password') {
-                    $entry->{crypt_pass} = PVE::Tools::encrypt_pw($v);
+                    $entry->{crypt_pass} = PVE::Tools::encrypt_pw($v, "y");
                 } else {
                     $entry->{$k} = $v;
                 }
diff --git a/src/PMG/AccessControl.pm b/src/PMG/AccessControl.pm
index f4ac743..6fa89de 100644
--- a/src/PMG/AccessControl.pm
+++ b/src/PMG/AccessControl.pm
@@ -103,7 +103,7 @@ sub set_user_password {
 
         my $cmd = ['usermod'];
 
-        my $epw = PVE::Tools::encrypt_pw($password);
+        my $epw = PVE::Tools::encrypt_pw($password, "y");
 
         push @$cmd, '-p', $epw, $ruid;
 
diff --git a/src/PMG/UserConfig.pm b/src/PMG/UserConfig.pm
index 5ee7333..b2ef417 100644
--- a/src/PMG/UserConfig.pm
+++ b/src/PMG/UserConfig.pm
@@ -19,6 +19,7 @@ my $config_filename = '/etc/pmg/user.conf';
 
 my $tfa_inotify_file_id = 'pmg-tfa.json';
 my $tfa_config_filename = '/etc/pmg/tfa.json';
+my $hash_prefix = "y";
 
 sub new {
     my ($type) = @_;
@@ -351,6 +352,12 @@ sub authenticate_user {
     if ($data->{crypt_pass}) {
         my $encpw = crypt($password, $data->{crypt_pass});
         die "invalid credentials\n" if ($encpw ne $data->{crypt_pass});
+
+        # If the password was stored with a different hash function than the currently configured
+        # one, update it here.
+        if ($data->{crypt_pass} !~ m/^\$${hash_prefix}\$/) {
+            store_password($class, $config, $realm, $username, $password);
+        }
     } else {
         die "no password set\n";
     }
@@ -364,7 +371,7 @@ sub set_user_password {
     lock_config(sub {
         my $cfg = $class->new();
         my $data = $cfg->lookup_user_data($username); # user exists
-        my $epw = PVE::Tools::encrypt_pw($password);
+        my $epw = PVE::Tools::encrypt_pw($password, $hash_prefix);
         $data->{crypt_pass} = $epw;
         $cfg->write();
     });
-- 
2.47.3