Use case-insensitive search for user lookup by external_auth_id

Almost all of the typical values of ldap['login_attribute'] are case
insensitive according to the LDAP schema. However, we previously used a
case-sensitive lookup when trying to find an existing user record.

This commit changes the default lookup to be case insensitive but
provides a user-controllable override for the rare case where users are
setting a case-sensitive login_attribute.

ChangeLog-Entry: Fix bug where logins via LDAP failed because of case
sensitivity.

omnibus/files/private-chef-cookbooks/private-chef/attributes/default.rb

@@ -666,6 +666,9 @@
 # default['private_chef']['ldap']['base_dn'] = "OU=Employees,OU=Domain users,DC=example,DC=com"
 # default['private_chef']['ldap']['timeout'] = 60000
 # default['private_chef']['ldap']['port'] = 389
+## Nearly every attribute in the standard LDAP schema that users likely set login_attr
+## to is case sensitive.
+# default['private_chef']['ldap']['case_sensitive_login_attribute'] = false
 #
 # default['private_chef']['ldap']['enable_ssl'] = false
 # default['private_chef']['ldap']['enable_tls'] = false

omnibus/files/private-chef-cookbooks/private-chef/templates/default/oc_erchef.config.erb

@@ -84,6 +84,7 @@
                       {base_dn, "<%= node['private_chef']['ldap']['base_dn'] || "" %>" },
                       {group_dn, "<%= node['private_chef']['ldap']['group_dn'] || "" %>" },
                       {login_attribute, "<%= node['private_chef']['ldap']['login_attribute'] || "samaccountname" %>" },
+                      {case_sensitive_login_attribute, <%= node['private_chef']['ldap']['case_sensitive_login_attribute'] || false %>},
                       {encryption, <%= @ldap_encryption_type %>}
               ]},
               <% else -%>

src/oc_erchef/apps/chef_db/priv/pgsql_statements.config

@@ -508,17 +508,32 @@
       recovery_authentication_enabled, serialized_object
       FROM users u
  LEFT JOIN keys k ON u.id = k.id AND key_name = 'default'
-     WHERE external_authentication_uid = $1">>}.
+     WHERE lower(external_authentication_uid) = lower($1)">>}.
 
 {find_user_by_external_authentication_uid,
   <<"SELECT u.id, authz_id, username, email,
       hashed_password, salt, hash_type, u.last_updated_by, u.created_at,
       u.updated_at, external_authentication_uid,
       recovery_authentication_enabled, serialized_object
       FROM users u
-     WHERE external_authentication_uid = $1">>}.
+     WHERE lower(external_authentication_uid) = lower($1)">>}.
 
+{find_user_by_sensitive_external_authentication_uid_v0,
+  <<"SELECT u.id, authz_id, username, email, k.public_key, k.key_version pubkey_version,
+      hashed_password, salt, hash_type, u.last_updated_by, u.created_at,
+      u.updated_at, external_authentication_uid,
+      recovery_authentication_enabled, serialized_object
+      FROM users u
+ LEFT JOIN keys k ON u.id = k.id AND key_name = 'default'
+     WHERE external_authentication_uid = $1">>}.
 
+{find_user_by_sensitive_external_authentication_uid,
+  <<"SELECT u.id, authz_id, username, email,
+      hashed_password, salt, hash_type, u.last_updated_by, u.created_at,
+      u.updated_at, external_authentication_uid,
+      recovery_authentication_enabled, serialized_object
+      FROM users u
+     WHERE external_authentication_uid = $1">>}.
 
 {delete_user_by_id,
   <<"DELETE FROM users WHERE id = $1">>}.

src/oc_erchef/apps/chef_objects/src/chef_user.erl

@@ -466,15 +466,27 @@ bulk_get_query(_ObjectRec) ->
 is_indexed(_ObjectRec) ->
     false.
 
-fetch(#chef_user{server_api_version = ?API_v0, username = undefined, external_authentication_uid = AuthUid} = Record, CallbackFun) ->
-    fetch_user(find_user_by_external_authentication_uid_v0, Record, AuthUid, CallbackFun);
-fetch(#chef_user{username = undefined, external_authentication_uid = AuthUid} = Record, CallbackFun) ->
-    fetch_user(find_user_by_external_authentication_uid, Record, AuthUid, CallbackFun);
+fetch(#chef_user{server_api_version = ApiVersion,
+                 username = undefined, external_authentication_uid = AuthUid} = Record, CallbackFun) ->
+    fetch_user(external_auth_id_query(ApiVersion, case_sensitivity()), Record, AuthUid, CallbackFun);
 fetch(#chef_user{server_api_version = ?API_v0, username = UserName} = Record, CallbackFun) ->
     fetch_user(find_user_by_username_v0, Record, UserName, CallbackFun);
 fetch(#chef_user{username = UserName} = Record, CallbackFun) ->
     fetch_user(find_user_by_username, Record, UserName, CallbackFun).
 
+case_sensitivity() ->
+    LdapConfig = envy:get(oc_chef_wm, ldap, [], list),
+    proplists:get_value(case_sensitive_login_attribute, LdapConfig, false).
+
+external_auth_id_query(?API_v0, true) ->
+    find_user_by_sensitive_external_authentication_uid_v0;
+external_auth_id_query(?API_v0, _NotSensitive) ->
+    find_user_by_external_authentication_uid_v0;
+external_auth_id_query(_Not0, true) ->
+    find_user_by_sensitive_external_authentication_uid;
+external_auth_id_query(_Not0, _NotSensitive) ->
+    find_user_by_external_authentication_uid.
+
 fetch_user(Query, Record, KeyValue, CallbackFun) ->
     CallbackFun({Query, [KeyValue],
                  {first_as_record, [chef_user, record_fields(Record)]}}).