From 2073c03092d328e4b5fd19882ecfbe491dc8b5c7 Mon Sep 17 00:00:00 2001
From: Timshel <github@mailtm.org>
Date: Sat, 29 Aug 2026 15:02:22 +0000
Subject: [PATCH] Add SSO_SIGNUPS_ALLOWED (#7272)

* Add SSO_SIGNUPS_ALLOWED

* Fix regression with domain_allowed in SSO onboarding

---------

Co-authored-by: Timshel <timshel@users.noreply.github.com>
---
 .env.template       |  3 +++
 src/api/identity.rs | 28 +++++++++++++++++++++++++++-
 src/config.rs       | 13 +++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/.env.template b/.env.template
index 9fc29989..5f6f374c 100644
--- a/.env.template
+++ b/.env.template
@@ -518,6 +518,9 @@
 ## Prevent users from logging in directly without going through SSO
 # SSO_ONLY=false
 
+## Allow SSO flow to create account. You probably want to disable it when using a public provider.
+# SSO_SIGNUPS_ALLOWED=true
+
 ## On SSO Signup if a user with a matching email already exists make the association
 # SSO_SIGNUPS_MATCH_EMAIL=true
 
diff --git a/src/api/identity.rs b/src/api/identity.rs
index 23411dc7..2b1ddfb1 100644
--- a/src/api/identity.rs
+++ b/src/api/identity.rs
@@ -234,6 +234,24 @@ async fn sso_login(
                     }
                 )
             }
+            Some((user, None))
+                if user.private_key.is_none()
+                    && !CONFIG.sso_signups_allowed()
+                    && !CONFIG.is_email_domain_allowed(&user.email)
+                    && !CONFIG.mail_enabled()
+                    && Invitation::find_by_mail(&user.email, conn).await.is_none() =>
+            {
+                error!(
+                    "Login failure ({}), no invitation with email ({}) was found",
+                    user_infos.identifier, user.email
+                );
+                err_silent!(
+                    "Missing invitation",
+                    ErrorEvent {
+                        event: EventType::UserFailedLogIn
+                    }
+                )
+            }
             Some((user, None)) if user.private_key.is_some() && !CONFIG.sso_signups_match_email() => {
                 error!(
                     "Login failure ({}), existing non SSO user ({}) with same email ({}) and association is disabled",
@@ -281,7 +299,15 @@ async fn sso_login(
     // Will trigger 2FA flow if needed
     let (user, mut device, twofactor_token, sso_user) = match user_with_sso {
         None => {
-            if !CONFIG.is_email_domain_allowed(&user_infos.email) {
+            if !CONFIG.is_sso_signup_allowed(&user_infos.email) {
+                if CONFIG.signups_domains_whitelist().is_empty() {
+                    err!(
+                        "Signups are disabled. You will need an invitation",
+                        ErrorEvent {
+                            event: EventType::UserFailedLogIn
+                        }
+                    );
+                }
                 err!(
                     "Email domain not allowed",
                     ErrorEvent {
diff --git a/src/config.rs b/src/config.rs
index 72b58252..2502dd02 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -817,6 +817,8 @@ make_config! {
         sso_enabled:                    bool,   true,   def,    false;
         /// Only SSO login |> Disable Email+Master Password login
         sso_only:                       bool,   true,   def,    false;
+        /// Allow SSO flow to create account |> You probably want to disable it when using a public provider
+        sso_signups_allowed:            bool,   true,   def,    true;
         /// Allow email association |> Associate existing non-SSO user based on email
         sso_signups_match_email:        bool,   true,   def,    true;
         /// Allow unknown email verification status |> Allowing this with `SSO_SIGNUPS_MATCH_EMAIL=true` open potential account takeover.
@@ -1544,6 +1546,17 @@ impl Config {
         }
     }
 
+    /// Tests whether SSO signup is allowed for an email address, taking into
+    /// account the sso_signups_allowed and signups_domains_whitelist settings.
+    pub fn is_sso_signup_allowed(&self, email: &str) -> bool {
+        if self.signups_domains_whitelist().is_empty() {
+            self.sso_signups_allowed()
+        } else {
+            // The whitelist setting overrides the signups_allowed setting.
+            self.is_email_domain_allowed(email)
+        }
+    }
+
     // The registration link should be hidden if
     //  - Signup is not allowed and email whitelist is empty unless mail is disabled and invitations are allowed
     //  - The SSO is activated and password login is disabled.