PAM: T5577: Optimized RADIUS PAM config

- Added system `radius` group
- Added `mandatory` and `optional` modes for RADIUS
- Improved PAM config for RADIUS

New modes:

- `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.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/pam-configs/radius-optional b/src/pam-configs/radius-optional
new file mode 100644
index 000000000..73085061d
--- /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 success=end] 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 user_unknown=bad] pam_radius_auth.so