readme index

must be cleaned

README.md

@@ -1,13 +1,36 @@
+
 # PostgreSQL expiration date management functions
 
+## Table of Contents
+
+1. [TOC](README.md#postgresql-expiration-date-management-functions)
+	1. [Description](README.md#description)
+	2. [Instructions](README.md#instructions)
+	3. [Helper script](README.md#helper-script)
+	4. [RDS considerations](README.md#rds-considerations)
+	5. [Security considerations](README.md#security-considerations)
+
 ## Description
 
 This project tries to find a way to allow users the management of the `VALID UNTIL` expiration clause by themself.
-All without granting `super` permissions and having a histoc of changes on a _pseudo-audit_ table
+Everyghin without granting `super` permissions and having a histoc of changes on a _pseudo-audit_ table.
+
+You can easly combine this functions with the [passwordcheck extra](https://github.com/michaelpq/pg_plugins/tree/main/passwordcheck_extra) extension, the regex inside `dba.change_valid_until` match the _default_ requirements in the extension for special characters and you can change the variable `_min_password_length` to match your requirements (in the case you changed it, of course).
+
+
+| :warning: WARNING          |
+|:---------------------------|
+| Amazon RDS has some notes at the end... |
+| :warning: WARNING          |
 
 ## Instructions
 
 ### First deploy
+
+Modify `passchanger.sql` according your needings:
+  * Change `_min_password_length` on `change_my_password` function
+  * Change `_password_lifetime` on `change_valid_until` function
+
 Deploy `passchanger.sql` on the desired cluster/database.
 
 It will:
@@ -18,6 +41,17 @@ It will:
   * Create the 2 needed functions and grant permissions on them to `dba`
 
 
+### Updates
+
+Just execute the `CREATE OR REPLACE FUNCTION` part of the `passchanger.sql` file.
+
+| :warning: WARNING          |
+|:---------------------------|
+| Amazon RDS has some notes at the end... |
+| :warning: WARNING          |
+
+
+
 ### Allowing users to use that functions
 Take the file `grants_to_grant.sql` and modify the username _dodger_ so it match the username that should have the permissions.
 Execute the grants on the cluster/database you have deployed `passchanger.sql`
@@ -43,3 +77,26 @@ dodger@ciberterminal.net $ bash password_creator.sh
 select dba.change_my_password('<Wl}TxqRPBQaV_N<rU#A') ;
 -- ##############################################
 ```
+
+
+## RDS considerations
+
+As Amazon has modified Postgresql so you don't have access as a *real* superuser and the _dangerous_ function
+`change_valid_until` should run as the owner of the database (the user created when you deploy the database through AWS)
+
+There's a `passchanger_rds.sql` file which should be used instead of the normal one.
+
+For updates you should change the owner of the `change_valid_until` to the database _owner_:
+```
+ALTER FUNCTION dba.change_valid_until(text) OWNER TO _DATABASEOWNER;
+```
+Modify `_DATABASEOWNER` according your admin username...
+
+
+## Security considerations
+
+  * Non-RDS `change_valid_until` function does not uses `ALTER USER` to modify `VALID UNTIL`, it makes an `update pg_catalog.pg_authid set rolvaliduntil` instead, so the `dba` user has only grant over that table/column instead of granting additional permissions to him.
+  * RDS `change_valid_until` should run as the database owner, is the only way to make this work as you can't access `pg_catalog.pg_authid` on rds, it uses `ALTER USER ... VALID UNTIL` instead.
+
+
+

grants_to_grant.sql

@@ -5,8 +5,12 @@ grant usage on schema dba to dodger ;
 -- grant execute on the function change_my_password
 grant execute on function dba.change_my_password(text) to dodger;
 -- grant execute on the function change_valid_until
-grant execute on function dba.change_valid_until(text) to dodger;
+grant execute on function dba.change_valid_until(text, text) to dodger;
 
 -- only insert is needed to allow audit trace
 GRANT INSERT ON TABLE dba.pwdhistory TO dodger;
 
+
+
+-- SET SESSION AUTORIZATION dodger ;
+

passchanger.sql

@@ -39,6 +39,8 @@ ALTER TABLE IF EXISTS dba.pwdhistory
 -- ######################################
 -- ######################################
 
+drop function if exists dba.change_valid_until ;
+
 CREATE OR REPLACE FUNCTION dba.change_valid_until(_usename text)
     RETURNS integer
     SECURITY DEFINER
@@ -49,30 +51,45 @@ AS $BODY$
 declare
     _invokingfunction text := '';
     _matches text;
+    _password_lifetime integer := 120 ;  -- specify password lifetime in days
+    _retval  INTEGER;
+    _expiration_date numeric ;
 begin
+    select extract(epoch from localtimestamp) into _expiration_date;
+    select _expiration_date+(_password_lifetime*24*60*60) into _expiration_date;
+
     select query into _invokingfunction from pg_stat_activity where pid = pg_backend_pid() ;
---     raise notice 'Invoking function: %', _invokingfunction;
+    -- first, checking the invoking function
-    --_matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\(''([[:alnum:]]|@|\\$|#|%|\\^|&|\\*|\\(|\\)|\\_|\\+|\\{|\\}|\\||<|>|\\?|=){1,100}''\\)[[:space:]]{0,};' , 'i');
+    _matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\(.*\\)[[:space:]]{0,};' , 'i');
-    _matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\(''([[:alnum:]]|@|\\$|#|%|\\^|&|\\*|\\(|\\)|\\_|\\+|\\{|\\}|\\||<|>|\\?|=|!){11,100}''\\)[[:space:]]{0,};' , 'i');
---     raise notice 'Matches: %', _matches;
     if _matches IS NOT NULL then
-      EXECUTE format('update pg_catalog.pg_authid set rolvaliduntil=now() + interval ''120 days'' where rolname=''%I'' ', _usename);
+      -- then checking the regex for the password
-      return 0;
+        _matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\([[:space:]]{0,}''([[:alnum:]]|@|\\$|#|%|\\^|&|\\*|\\(|\\)|\\_|\\+|\\{|\\}|\\||<|>|\\?|=|!){11,100}''[[:space:]]{0,}\\)[[:space:]]{0,};' , 'i');
-    else  -- also catches NULL
+        if _matches IS NOT NULL then
+            EXECUTE format('update pg_catalog.pg_authid set rolvaliduntil=to_timestamp(%L) where rolname=%L ', _expiration_date, _usename);
+            -- INTO _retval;
+            RETURN 0;
+        else
+            raise exception 'Regular expresion for password check failed'
+            using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+            , detail = 'Check your generated password an try again'
+            , hint = 'Read the official documentation' ;
+            RETURN 1;
+        end if;
+    else  
+      -- also catches NULL
       -- raise custom error
       raise exception 'You''re not allowed to run this function directly'
       using errcode = '22023'  -- 22023 = "invalid_parameter_value'
           , detail = 'Please call dba.change_my_password function.'
           , hint = 'Invoked function: ' || _invokingfunction ;
+      RETURN 1;
     end if;
 end
 $BODY$;
 
-ALTER FUNCTION dba.change_valid_until(text)
+ALTER FUNCTION dba.change_valid_until(text) OWNER TO dba;
-    OWNER TO dba;
 REVOKE EXECUTE ON FUNCTION dba.change_valid_until(text) From PUBLIC;
 
-
 CREATE OR REPLACE FUNCTION dba.change_my_password(_password text)
     RETURNS integer
     SECURITY INVOKER
@@ -81,39 +98,55 @@ CREATE OR REPLACE FUNCTION dba.change_my_password(_password text)
     VOLATILE PARALLEL UNSAFE
 AS $BODY$
 declare
-   _min_password_length int := 8;  -- specify min length here
+    _min_password_length int := 12;  -- specify min length here
     _usename text := '';
     _useraddress text := '';
     _userapp text := '';
+    _retval integer ;
 begin
    select user into _usename;
-   select client_addr into _useraddress from pg_stat_activity where pid = pg_backend_pid() ;
+   if user = 'postgres' then
-   select application_name into _userapp from pg_stat_activity where pid = pg_backend_pid() ;
+      raise exception 'This function should not be run by user postgres'
-   if length(_password) >= _min_password_length then
+      using errcode = '22024'  -- 22023 = "invalid_parameter_value'
-      EXECUTE format('ALTER USER %I WITH PASSWORD %L', _usename, _password);
+          , detail = 'Use a named user only.' ;
-   else  -- also catches NULL
+      return 1;
+   end if;
+
+   if length(_password) < _min_password_length then
+      -- also catches NULL
       -- raise custom error
       raise exception 'Password too short!'
       using errcode = '22023'  -- 22023 = "invalid_parameter_value'
           , detail = 'Please check your password.'
           , hint = 'Password must be at least ' || _min_password_length || ' characters.';
+      return 1;
    end if;
-   if user = 'postgres' then
+
-      raise exception 'This function should not be run by user postgres'
+   select client_addr into _useraddress from pg_stat_activity where pid = pg_backend_pid() ;
-      using errcode = '22024'  -- 22023 = "invalid_parameter_value'
+   select application_name into _userapp from pg_stat_activity where pid = pg_backend_pid() ;
-          , detail = 'Use a named user only.' ;
+
-   else 
+    --PERFORM dba.change_valid_until(_usename) ;
+    SELECT dba.change_valid_until(_usename)
+        INTO _retval;
+    -- this will be executed by the username invoking this function
+    if _retval = 0 then
+        EXECUTE format('ALTER USER %I WITH PASSWORD %L', _usename, _password);
         insert into dba.pwdhistory
                (usename, usename_addres, application_name, password, changed_on)
         values (_usename, _useraddress, _userapp, md5(_password),now());
-       PERFORM dba.change_valid_until(_usename) ;
+
+        raise notice 'Password changed' ;
+    else
+        raise exception 'Could not change expiration date, please check'
+        using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+            , detail = 'contact the dba' ;
+        return 1;
     end if;
 
     return 0;
 end
 $BODY$;
 
-ALTER FUNCTION dba.change_my_password(text)
+ALTER FUNCTION dba.change_my_password(text) OWNER TO dba;
-    OWNER TO dba;
 REVOKE EXECUTE ON FUNCTION dba.change_my_password(text) From PUBLIC;
 

passchanger_rds.sql

@@ -0,0 +1,156 @@
+
+-- Schema creation
+create schema dba ;
+
+-- role creation
+create role dba with NOLOGIN NOINHERIT ;
+
+-- grants for dba
+-- GRANT rds_superuser TO dba ;
+
+-- grant select on pg_catalog.pg_authid to dba ;
+-- grant pg_read_all_stats to dba ;
+
+-- password history table
+CREATE TABLE IF NOT EXISTS dba.pwdhistory
+(
+    usename character varying COLLATE pg_catalog."default",
+    usename_addres character varying COLLATE pg_catalog."default",
+    application_name character varying COLLATE pg_catalog."default",
+    password character varying COLLATE pg_catalog."default",
+    changed_on timestamp without time zone
+)
+TABLESPACE pg_default;
+
+-- alter if you come from a previous version of the table:
+-- alter table dba.pwdhistory add column usename_addres character varying ;
+-- alter table dba.pwdhistory add column application_name character varying ;
+
+ALTER TABLE IF EXISTS dba.pwdhistory
+    OWNER to dba;
+
+
+
+-- ######################################
+-- ######################################
+
+-- real functions
+
+-- ######################################
+-- ######################################
+
+drop function if exists dba.change_valid_until ;
+
+CREATE OR REPLACE FUNCTION dba.change_valid_until(_usename text, _thepassword text)
+    RETURNS integer
+    SECURITY DEFINER
+    LANGUAGE 'plpgsql'
+    COST 100
+    VOLATILE PARALLEL UNSAFE
+AS $BODY$
+declare
+    _invokingfunction text := '';
+    _matches text;
+    _password_lifetime integer := 120 ;  -- specify password lifetime in days
+    _retval  integer;
+    _expiration_epoch numeric ;
+    _expiration_date timestamp ;
+begin
+    select extract(epoch from localtimestamp) into _expiration_epoch;
+    select _expiration_epoch+(_password_lifetime*24*60*60) into _expiration_epoch;
+    select to_timestamp(_expiration_epoch) into _expiration_date ;
+
+    select query into _invokingfunction from pg_stat_activity where pid = pg_backend_pid() ;
+    -- first, checking the invoking function
+    _matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\(.*\\)[[:space:]]{0,};' , 'i');
+    if _matches IS NOT NULL then
+        -- then checking the regex for the password
+        _matches := regexp_matches(_invokingfunction, E'select dba\.change_my_password\\([[:space:]]{0,}''([[:alnum:]]|@|\\$|#|%|\\^|&|\\*|\\(|\\)|\\_|\\+|\\{|\\}|\\||<|>|\\?|=|!){11,100}''[[:space:]]{0,}\\)[[:space:]]{0,};' , 'i');
+        if _matches IS NOT NULL then
+--            EXECUTE format('ALTER ROLE %I WITH PASSWORD %L VALID UNTIL to_timestamp(%L) ;', _usename, _thepassword, _expiration_date);
+            EXECUTE format('ALTER ROLE %I WITH PASSWORD %L VALID UNTIL %L ;', _usename, _thepassword, _expiration_date);
+            -- INTO _retval;
+            RETURN 0;
+        else
+            raise exception 'Regular expresion for password check failed'
+            using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+            , detail = 'Check your generated password (' || _thepassword || ') an try again'
+            , hint = 'Read the official documentation' ;
+            RETURN 1;
+        end if;
+    else  
+      -- also catches NULL
+      -- raise custom error
+      raise exception 'You''re not allowed to run this function directly'
+      using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+          , detail = 'Please call dba.change_my_password function.'
+          , hint = 'Invoked function: ' || _invokingfunction ;
+      RETURN 1;
+    end if;
+end
+$BODY$;
+
+-- ALTER FUNCTION dba.change_valid_until(text, text) OWNER TO dba;
+REVOKE EXECUTE ON FUNCTION dba.change_valid_until(text, text) From PUBLIC;
+
+
+drop function if exists dba.change_my_password ;
+
+CREATE OR REPLACE FUNCTION dba.change_my_password(_password text)
+    RETURNS integer
+    SECURITY INVOKER
+    LANGUAGE 'plpgsql'
+    COST 100
+    VOLATILE PARALLEL UNSAFE
+AS $BODY$
+declare
+    _min_password_length int := 12;  -- specify min length here
+    _usename text := '';
+    _useraddress text := '';
+    _userapp text := '';
+    _retval integer ;
+begin
+    select user into _usename;
+    if user = 'postgres' then
+        raise exception 'This function should not be run by user postgres'
+        using errcode = '22024'  -- 22023 = "invalid_parameter_value'
+          , detail = 'Use a named user only.' ;
+      return 1;
+    end if;
+
+    if length(_password) < _min_password_length then
+      -- also catches NULL
+      -- raise custom error
+      raise exception 'Password too short!'
+      using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+          , detail = 'Please check your password.'
+          , hint = 'Password must be at least ' || _min_password_length || ' characters.';
+      return 1;
+    end if;
+
+    select client_addr into _useraddress from pg_stat_activity where pid = pg_backend_pid() ;
+    select application_name into _userapp from pg_stat_activity where pid = pg_backend_pid() ;
+
+    --PERFORM dba.change_valid_until(_usename, _password) ;
+    SELECT dba.change_valid_until(_usename, _password)
+        INTO _retval;
+    if _retval = 0 then
+        insert into dba.pwdhistory
+               (usename, usename_addres, application_name, password, changed_on)
+        values (_usename, _useraddress, _userapp, md5(_password),now());
+
+        raise notice 'Password changed' ;
+    else
+        raise exception 'Could not change expiration date, please check'
+        using errcode = '22023'  -- 22023 = "invalid_parameter_value'
+            , detail = 'contact the dba' ;
+        return 1;
+    end if;
+
+    return 0;
+end
+$BODY$;
+
+ALTER FUNCTION dba.change_my_password(text) OWNER TO dba;
+REVOKE EXECUTE ON FUNCTION dba.change_my_password(text) From PUBLIC;
+