Permission inconsistency with views that call functions

Hi all

I’m seeing some inconsistency with how permissions are enforced within views. In particular, if the view accesses a table directly, then the table is accessible, however if the view uses a function to access the table then permission is denied.

Here’s a demonstration (from pg13.0)

createdb temp

psql temp <<\EOF

create schema hidden;

create table hidden.tab (col1 text);

insert into hidden.tab values ('abc');

create function test() returns text[] as $$

  select array_agg(col1) from hidden.tab;

$$ language sql stable;

create view tv1 as select test();

create view tv2 as select array_agg(col1) from hidden.tab;

grant select on tv1 to public;

grant select on tv2 to public;

create user test password 'test' login;

EOF

PGPASSWORD=test psql -U test temp <<\EOF

\echo select * from tv1;

select * from tv1;

\echo ---------------

\echo select * from tv2;

select * from tv2;

set jit_inline_above_cost to -1;

\echo ---------------

\echo select * from tv1; -- no jit inlining

select * from tv1;

EOF

OUTPUT

ERROR:  permission denied for schema hidden

LINE 2:   select array_agg(col1) from hidden.tab;

                                      ^

QUERY:

  select array_agg(col1) from hidden.tab;

CONTEXT:  SQL function "test" during inlining

---------------

select * from tv2;

array_agg

-----------

{abc}

(1 row)

SET

---------------

select * from tv1; -- no jit inlining

ERROR:  permission denied for schema hidden

LINE 2:   select array_agg(col1) from hidden.tab;

                                      ^

QUERY:

  select array_agg(col1) from hidden.tab;

CONTEXT:  SQL function "test" during inlining

Is this expected/desirable? Any ideas how I can work around it, short of inlining every function manually (if that’s even possible) or granting access to the “hidden” schema?

Thanks in advance!

Best regards,

David Wheeler, Inomial Architect

E. [hidden email]

313 La Trobe Street, Victoria 3000, Australia

+61 3 8820 5200

MELBOURNE . DENPASAR . AUCKLAND

WWW.DGITSYSTEMS.COM

Thanks for the reply

> VIEWs operate as if they were "SECURITY DEFINER".

My concern is that the view is not acting as a security barrier underneath which all access is evaluated using the view owner context; in some circumstances (when the view calls a function) the access is evaluated using the caller’s context.

Caller

   |

   |

  V

- View --------------   Security definition layer 

   |

  |---- (b)

   |    |

(a)|    v

   |  Function (not SECURITY DEFINER or explicitly SECURITY INVOKER)

   |    |

   |    |

   |    |

  V    x

   Table

I would expect that everything underneath the View would use the view owner to evaluate permissions. However it seems that in scenario (b) it enters a new security context from the caller, rather than inheriting it from the view.

> The solution to your issue is possibly to make the function "SECURITY DEFINER".

This works, but I see this as a workaround, because the function is simply a utility that makes understanding the data in the table a little easier. Why should it be security definer? If you don’t have access to the table you shouldn’t be able to use the function to access it.

David

On 24/2/21, 2:41 am, "Joe Conway" <[hidden email]> wrote: