函数内容比较敏感时, 如何提高函数内容的隐射或安全性呢?
1. 可以使用加密函数的方法来提高安全性. 需要安装额外的插件.
2. 可以使用C函数, 用户无法看到函数内容.
3. 如果以上方法无法在你的生产环境实施的话, 那么可以通过控制pg_proc的权限来控制谁可以看到函数内容.
例如, 我们这里创建一个测试函数 :
函数内容存在pg_proc.prosrc字段中.
创建一个普通用户, 因为pg_proc的权限给public角色了, 所以普通用户也可以查询到它的内容.
postgres=# create or replace function f() returns int as $$
postgres$# declare
postgres$# a int := 10;
postgres$# begin
postgres$# return a;
postgres$# end;
postgres$# $$ language plpgsql;
CREATE FUNCTION函数内容存在pg_proc.prosrc字段中.
postgres=# select prosrc from pg_proc where proname='f';
prosrc
---------------
+
declare +
a int := 10;+
begin +
return a; +
end; +
(1 row)创建一个普通用户, 因为pg_proc的权限给public角色了, 所以普通用户也可以查询到它的内容.
postgres=# create role test login;
CREATE ROLE
postgres=# \c postgres test
You are now connected to database "postgres" as user "test".
postgres=> select prosrc from pg_proc where proname='f';
prosrc
---------------
+
declare +
a int := 10;+
begin +
return a; +
end; +
(1 row)
仅仅回收prosrc字段的权限是不够的, 为什么呢? 参考
http://www.postgresql.org/docs/9.4/static/sql-revoke.html
将pg_proc的权限从public回收即可.
但是这样做的话, 所有的普通用户都没有了查询权限, 包括不能列出函数名.
其他普通用户, 需要查询函数名, 必须赋予pg_proc的查询权限.
这样就控制了某个用户没有查询函数, 函数内容的权限.
postgres=> \c postgres postgres
You are now connected to database "postgres" as user "postgres".
postgres=# revoke select(prosrc) on pg_proc from public;
REVOKE
postgres=# \c postgres test
You are now connected to database "postgres" as user "test".
postgres=> select prosrc from pg_proc where proname='f';
prosrc
---------------
+
declare +
a int := 10;+
begin +
return a; +
end; +
(1 row)将pg_proc的权限从public回收即可.
postgres=> \c postgres postgres
You are now connected to database "postgres" as user "postgres".
postgres=# revoke select on pg_proc from public;
REVOKE
postgres=# \c postgres test
You are now connected to database "postgres" as user "test".
postgres=> select prosrc from pg_proc where proname='f';
ERROR: permission denied for relation pg_proc
postgres=> select proname from pg_proc where proname='f';
ERROR: permission denied for relation pg_proc但是这样做的话, 所有的普通用户都没有了查询权限, 包括不能列出函数名.
postgres=> \c postgres postgres
You are now connected to database "postgres" as user "postgres".
postgres=# \du
List of roles
Role name | Attributes | Member of
-----------+------------------------------------------------+-----------
d | | {}
postgres | Superuser, Create role, Create DB, Replication | {}
test | | {}
postgres=> \df
ERROR: permission denied for relation pg_proc其他普通用户, 需要查询函数名, 必须赋予pg_proc的查询权限.
postgres=# grant select on pg_proc to d;
GRANT
postgres=# \c postgres d
You are now connected to database "postgres" as user "d".
postgres=> select prosrc from pg_proc where proname='f';
prosrc
---------------
+
declare +
a int := 10;+
begin +
return a; +
end; +
(1 row)这样就控制了某个用户没有查询函数, 函数内容的权限.
postgres=> \c postgres test
You are now connected to database "postgres" as user "test".
postgres=> select prosrc from pg_proc where proname='f';
ERROR: permission denied for relation pg_proc
如果要做到可以列出函数名, 但是不能查询函数内容. 怎么做呢?
首先我们要知道列函数用到什么QUERY
那么需要将除prosrc以外的所有字段(包括oid)都赋予给test用户即可.
现在test用户可以列函数名, 但是不能看函数内容了.
postgres@localhost-> psql -E
postgres=> \df
********* QUERY **********
SELECT n.nspname as "Schema",
p.proname as "Name",
pg_catalog.pg_get_function_result(p.oid) as "Result data type",
pg_catalog.pg_get_function_arguments(p.oid) as "Argument data types",
CASE
WHEN p.proisagg THEN 'agg'
WHEN p.proiswindow THEN 'window'
WHEN p.prorettype = 'pg_catalog.trigger'::pg_catalog.regtype THEN 'trigger'
ELSE 'normal'
END as "Type"
FROM pg_catalog.pg_proc p
LEFT JOIN pg_catalog.pg_namespace n ON n.oid = p.pronamespace
WHERE pg_catalog.pg_function_is_visible(p.oid)
AND n.nspname <> 'pg_catalog'
AND n.nspname <> 'information_schema'
ORDER BY 1, 2, 4;
**************************
ERROR: permission denied for relation pg_proc那么需要将除prosrc以外的所有字段(包括oid)都赋予给test用户即可.
postgres=# grant select(oid,proname,pronamespace,proowner,prolang,procost,prorows,provariadic,protransform,proisagg,proiswindow,prosecdef,proleakproof,proisstrict,proretset,provolatile,pronargs,pronargdefaults,prorettype,proargtypes,proallargtypes,proargmodes,proargnames,proargdefaults,probin,proconfig,proacl) on pg_proc to test;
GRANT
postgres=# \c postgres test
You are now connected to database "postgres" as user "test".现在test用户可以列函数名, 但是不能看函数内容了.
postgres=> select proname from pg_proc limit 1;
proname
---------
boolin
(1 row)
postgres=> select prosrc from pg_proc limit 1;
ERROR: permission denied for relation pg_proc
postgres=> \df
List of functions
Schema | Name | Result data type |
Argument data types
| Type
--------+-------------------------+---------------------------+---------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------+--------
public | dblink | SETOF record | text
| normal
public | dblink | SETOF record | text, boolean
但是, 别高兴太早, 函数的内容不是这么查出来的, 而是通过pg_get_functiondef(oid)系统函数来获取的, 所以还需要回收这个系统函数的权限.
在回收权限前.
回收权限后
postgres=> select * from pg_get_functiondef(16649);
pg_get_functiondef
---------------------------------------
CREATE OR REPLACE FUNCTION public.f()+
RETURNS integer +
LANGUAGE plpgsql +
AS $function$ +
declare +
a int := 10; +
begin +
return a; +
end; +
$function$ +
(1 row)
postgres=> \sf f
CREATE OR REPLACE FUNCTION public.f()
RETURNS integer
LANGUAGE plpgsql
AS $function$
declare
a int := 10;
begin
return a;
end;
$function$回收权限后
postgres=# revoke execute on function pg_get_functiondef(oid) from public;
REVOKE
postgres=> \c postgres postgres
You are now connected to database "postgres" as user "postgres".
postgres=# select oid from pg_proc where proname='f';
oid
-------
16649
(1 row)
postgres=# \c postgres test
You are now connected to database "postgres" as user "test".
postgres=> \sf f
ERROR: permission denied for function pg_get_functiondef
postgres=> select * from pg_get_functiondef(16649);
ERROR: permission denied for function pg_get_functiondef
[小结]
通过权限来控制普通用户是否有查看函数内容的权限方法.
第三步对于不同的PostgreSQL版本可能不一样, 请注意.
[参考]
1. revoke select on pg_proc from public;
2. grant select on pg_proc to 需要查看函数内容权限的普通用户;
3. grant select(oid,proname,pronamespace,proowner,prolang,procost,prorows,provariadic,protransform,proisagg,proiswindow,prosecdef,proleakproof,proisstrict,proretset,provolatile,pronargs,pronargdefaults,prorettype,proargtypes,proallargtypes,proargmodes,proargnames,proargdefaults,probin,proconfig,proacl) on pg_proc to 不需要查看函数内容权限的普通用户;
4. revoke select(prosrc) on pg_proc from 不需要查看函数内容权限的普通用户;
5.
postgres=# revoke execute on function pg_get_functiondef(oid) from public;
REVOKE
6.
postgres=# grant execute on function pg_get_functiondef(oid) to 需要查看函数内容权限的普通用户;
目前PostgreSQL在对象权限这块控制还是过于粗燥, 不像Oracle做得很细, 用户间的权限控制是非常严格的.
而Postgres-XL则做了一定的修改, 是在parser层面做的, 可参考 :
这也是一个路子.
When revoking privileges on a table, the corresponding column privileges (if any) are automatically revoked on each column of the table, as well. On the other hand, if a role has been granted privileges on a table, then revoking the same privileges from individual columns will have no effect.
