RADIUS: T5577: Added `mandatory` and `optional` modes for RADIUS

In CLI we can choose authentication logic:

  - `mandatory` - if RADIUS answered with `Access-Reject`, authentication must
  be stopped and access denied immediately.
  - `optional` (default) - if RADIUS answers with `Access-Reject`,
  authentication continues using the next module.

In `mandatory` mode authentication will be stopped only if RADIUS clearly
answered that access should be denied (no user in RADIUS database, wrong
password, etc.). If RADIUS is not available or other errors happen, it will be
skipped and authentication will continue with the next module, like in
`optional` mode.

7 files changed, 68 insertions, 27 deletions

diff --git a/debian/vyos-1x.postinst b/debian/vyos-1x.postinst
index 35fc67af8..a3c308e5f 100644
--- a/debian/vyos-1x.postinst
+++ b/debian/vyos-1x.postinst
@@ -91,7 +91,6 @@ if ! grep -q '^radius_user' /etc/passwd; then
     adduser --quiet radius_user adm
     adduser --quiet radius_user dip
     adduser --quiet radius_user users
-    adduser --quiet radius_user aaa
 fi
 
 # Add RADIUS admin user for RADIUS authenticated users to map to
@@ -107,7 +106,6 @@ if ! grep -q '^radius_priv_user' /etc/passwd; then
     adduser --quiet radius_priv_user disk
     adduser --quiet radius_priv_user users
     adduser --quiet radius_priv_user frr
-    adduser --quiet radius_priv_user aaa
 fi
 
 # add hostsd group for vyos-hostsd
diff --git a/debian/vyos-1x.preinst b/debian/vyos-1x.preinst
index e355ffa84..75fa5e7f1 100644
--- a/debian/vyos-1x.preinst
+++ b/debian/vyos-1x.preinst
@@ -2,7 +2,6 @@ dpkg-divert --package vyos-1x --add --no-rename /etc/securetty
 dpkg-divert --package vyos-1x --add --no-rename /etc/security/capability.conf
 dpkg-divert --package vyos-1x --add --no-rename /lib/systemd/system/lcdproc.service
 dpkg-divert --package vyos-1x --add --no-rename /etc/logrotate.d/conntrackd
-dpkg-divert --package vyos-1x --add --no-rename /usr/share/pam-configs/radius
 dpkg-divert --package vyos-1x --add --no-rename /usr/share/pam-configs/tacplus
 dpkg-divert --package vyos-1x --add --no-rename /etc/rsyslog.conf
 dpkg-divert --package vyos-1x --add --no-rename /etc/skel/.bashrc
diff --git a/interface-definitions/include/radius-server-ipv4-ipv6.xml.i b/interface-definitions/include/radius-server-ipv4-ipv6.xml.i
index efd418bb2..a0cdcd7c3 100644
--- a/interface-definitions/include/radius-server-ipv4-ipv6.xml.i
+++ b/interface-definitions/include/radius-server-ipv4-ipv6.xml.i
@@ -46,6 +46,26 @@
         <multi/>
       </properties>
     </leafNode>
+    <leafNode name="security-mode">
+      <properties>
+        <help>Security mode for RADIUS authentication</help>
+        <completionHelp>
+          <list>mandatory optional</list>
+        </completionHelp>
+        <valueHelp>
+          <format>mandatory</format>
+          <description>Deny access immediately if RADIUS answers with Access-Reject</description>
+        </valueHelp>
+        <valueHelp>
+          <format>optional</format>
+          <description>Pass to the next authentication method if RADIUS answers with Access-Reject</description>
+        </valueHelp>
+        <constraint>
+          <regex>(mandatory|optional)</regex>
+        </constraint>
+      </properties>
+      <defaultValue>optional</defaultValue>
+    </leafNode>
   </children>
 </node>
 <!-- include end -->
diff --git a/src/conf_mode/system-login.py b/src/conf_mode/system-login.py
index 02c97afaa..be5ff2d4c 100755
--- a/src/conf_mode/system-login.py
+++ b/src/conf_mode/system-login.py
@@ -104,6 +104,9 @@ def get_config(config=None):
     # prune TACACS global defaults if not set by user
     if login.from_defaults(['tacacs']):
         del login['tacacs']
+    # same for RADIUS
+    if login.from_defaults(['radius']):
+        del login['radius']
 
     # create a list of all users, cli and users
     all_users = list(set(local_users + cli_users))
@@ -377,11 +380,14 @@ def apply(login):
             except Exception as e:
                 raise ConfigError(f'Deleting user "{user}" raised exception: {e}')
 
-    # Enable RADIUS in PAM configuration
-    pam_cmd = '--remove'
+    # Enable/disable RADIUS in PAM configuration
+    cmd('pam-auth-update --disable radius-mandatory radius-optional')
     if 'radius' in login:
-        pam_cmd = '--enable'
-    cmd(f'pam-auth-update --package {pam_cmd} radius')
+        if login['radius'].get('security_mode', '') == 'mandatory':
+            pam_profile = 'radius-mandatory'
+        else:
+            pam_profile = 'radius-optional'
+        cmd(f'pam-auth-update --enable {pam_profile}')
 
     # Enable/Disable TACACS in PAM configuration
     pam_cmd = '--remove'
diff --git a/src/pam-configs/radius b/src/pam-configs/radius
deleted file mode 100644
index eee9cb93e..000000000
--- a/src/pam-configs/radius
+++ /dev/null
@@ -1,20 +0,0 @@
-Name: RADIUS authentication
-Default: no
-Priority: 257
-Auth-Type: Primary
-Auth:
-    [default=ignore success=2] pam_succeed_if.so service = sudo
-    [default=ignore success=ignore] pam_succeed_if.so user ingroup aaa quiet
-    [authinfo_unavail=ignore success=end default=ignore] pam_radius_auth.so
-
-Account-Type: Primary
-Account:
-    [default=ignore success=2] pam_succeed_if.so service = sudo
-    [default=ignore success=ignore] pam_succeed_if.so user ingroup aaa quiet
-    [authinfo_unavail=ignore success=end perm_denied=bad default=ignore] pam_radius_auth.so
-
-Session-Type: Additional
-Session:
-    [default=ignore success=2] pam_succeed_if.so service = sudo
-    [default=ignore success=ignore] pam_succeed_if.so user ingroup aaa quiet
-    [authinfo_unavail=ignore success=ok default=ignore] pam_radius_auth.so
diff --git a/src/pam-configs/radius-mandatory b/src/pam-configs/radius-mandatory
new file mode 100644
index 000000000..43b6bd3e0
--- /dev/null
+++ b/src/pam-configs/radius-mandatory
@@ -0,0 +1,19 @@
+Name: RADIUS authentication (mandatory mode)
+Default: no
+Priority: 576
+
+Auth-Type: Primary
+Auth-Initial:
+    [default=ignore success=end perm_denied=bad auth_err=bad] pam_radius_auth.so
+Auth:
+    [default=ignore success=end perm_denied=bad auth_err=bad] pam_radius_auth.so use_first_pass
+
+Account-Type: Primary
+Account:
+    [default=ignore success=1] pam_succeed_if.so user notingroup radius quiet
+    [default=ignore new_authtok_reqd=done success=end perm_denied=bad auth_err=bad] pam_radius_auth.so
+
+Session-Type: Additional
+Session:
+    [default=ignore success=1] pam_succeed_if.so user notingroup radius quiet
+    [default=ignore success=ok perm_denied=bad auth_err=bad] pam_radius_auth.so
diff --git a/src/pam-configs/radius-optional b/src/pam-configs/radius-optional
new file mode 100644
index 000000000..9f6d5f0ea
--- /dev/null
+++ b/src/pam-configs/radius-optional
@@ -0,0 +1,19 @@
+Name: RADIUS authentication (optional mode)
+Default: no
+Priority: 576
+
+Auth-Type: Primary
+Auth-Initial:
+    [default=ignore success=end] pam_radius_auth.so
+Auth:
+    [default=ignore success=end] pam_radius_auth.so use_first_pass
+
+Account-Type: Primary
+Account:
+    [default=ignore success=1] pam_succeed_if.so user notingroup radius quiet
+    [default=ignore new_authtok_reqd=done success=end perm_denied=bad auth_err=bad] pam_radius_auth.so
+
+Session-Type: Additional
+Session:
+    [default=ignore success=1] pam_succeed_if.so user notingroup radius quiet
+    [default=ignore success=ok perm_denied=bad auth_err=bad] pam_radius_auth.so