TACACS: T5577: Added `mandatory` and `optional` modes for TACACS+

In CLI we can choose authentication logic:

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

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

1 files changed, 7 insertions, 4 deletions

diff --git a/src/conf_mode/system-login.py b/src/conf_mode/system-login.py
index be5ff2d4c..87a269499 100755
--- a/src/conf_mode/system-login.py
+++ b/src/conf_mode/system-login.py
@@ -389,11 +389,14 @@ def apply(login):
             pam_profile = 'radius-optional'
         cmd(f'pam-auth-update --enable {pam_profile}')
 
-    # Enable/Disable TACACS in PAM configuration
-    pam_cmd = '--remove'
+    # Enable/disable TACACS+ in PAM configuration
+    cmd('pam-auth-update --disable tacplus-mandatory tacplus-optional')
     if 'tacacs' in login:
-        pam_cmd = '--enable'
-    cmd(f'pam-auth-update --package {pam_cmd} tacplus')
+        if login['tacacs'].get('security_mode', '') == 'mandatory':
+            pam_profile = 'tacplus-mandatory'
+        else:
+            pam_profile = 'tacplus-optional'
+        cmd(f'pam-auth-update --enable {pam_profile}')
 
     return None