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mason-sharp merged 1 commit into from
Sep 25, 2026
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Stop recording pg_shdepend rows lolor cannot describe. #54

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2 changes: 2 additions & 0 deletions README.md
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Expand Up @@ -124,4 +124,6 @@ database user. Upgrading to 1.3.0 revokes the privilege; see the release notes.

- Native large object functionality cannot be used while you are using the lolor extension.
- lolor does not support the following statements: `ALTER LARGE OBJECT`, `GRANT ON LARGE OBJECT`, `COMMENT ON LARGE OBJECT`, and `REVOKE ON LARGE OBJECT`.
- Objects in lolor storage are rows in ordinary tables and so cannot participate in `pg_shdepend`. `DROP ROLE`, `DROP OWNED BY` and `REASSIGN OWNED BY` do not see them: a role that owns them or appears in their ACL can be dropped without a warning, and `REASSIGN OWNED` / `DROP OWNED` leave them untouched. Before dropping a role, run `REASSIGN OWNED BY` or `DROP OWNED BY` in each database that has lolor, then `DROP ROLE`. Afterwards run `lolor.check_orphans()` in each such database and repair anything it reports with `lolor.fix_orphans(new_owner)`.
- Role OIDs come from a cluster-wide counter that wraps around, so a new role can receive a dropped role's OID and silently become the owner or grantee of that role's orphaned objects. This cannot be detected after the fact, which is another reason to run `lolor.check_orphans()` promptly after dropping roles.
- Large object migration is node-local. Native large objects live in `pg_catalog.pg_largeobject`, which is never replicated, so each node holds an independent set and `migrate_from_native()` migrates only the local node's objects; with spock installed, the migration DML runs in repair mode and is not replicated. Run the migration on every node that holds native large objects — for example with `spock.replicate_ddl('SELECT lolor.migrate_from_native()')`, which queues the command so that each node executes it locally. Migrated objects keep their original native OIDs, which are not node-encoded: if different nodes hold different objects under the same OID, the nodes' lolor contents will diverge and later replicated changes to those objects can conflict. Newly created large objects are collision-free, since new OIDs are node-encoded via `lolor.node` and checked against existing rows.
4 changes: 4 additions & 0 deletions docs/lolor_release_notes.md
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Expand Up @@ -11,6 +11,10 @@
* **Security fix: `lo_import()` and `lo_export()` were executable by any database user.** These read and write files on the server as the account PostgreSQL runs under, so core revokes `EXECUTE` on them from `PUBLIC`. lolor replaces them by renaming the originals to `*_orig`; an ACL belongs to a function rather than a name, so the restriction stayed on the parked original while each replacement got the default `EXECUTE TO PUBLIC`. Any user could read an arbitrary server file with `lo_import()` or overwrite one with `lo_export()`. The replacements are now locked down at install time, and upgrading revokes the privilege on existing installations in either state. Versions 1.0 through 1.2.2 are affected.
* The extension is no longer marked `trusted`. Installing lolor renames functions in `pg_catalog` for the whole database, which a non-superuser should not be able to do.
* Fixed the `lolor.node` upper bound. The GUC accepted 0..16 while a generated OID reserves four bits for the node id, so node 16 did not fit: the node field of every OID it generated read back as 0. The bound is now derived from the encoding (`LOLOR_MAX_NODE_ID`), giving 0..15. **If you have `lolor.node = 16` configured**, the server still starts but logs `16 is outside the valid range for parameter "lolor.node" (0 .. 15)` and falls back to 0, which is the node id it was effectively using already. Set it to a value in 0..15, and check for OID collisions against whichever node is genuinely 0.
* **Fixed `DROP ROLE` failing with "unrecognized object class".** Creating a large object recorded a `pg_shdepend` row whose `classId` was the OID of `lolor.pg_largeobject`, an ordinary table rather than a catalog. Any role that had created a large object became undroppable, and the rows were never cleaned up because `inv_drop()` deleted with `PERFORM_DELETION_SKIP_ORIGINAL`. lolor no longer records these rows, and the upgrade removes the ones already present.
* The cleanup is per database, so `ALTER EXTENSION lolor UPDATE` must be run in every database that has lolor. Until it is, `DROP ROLE` anywhere in the cluster keeps reporting "owner of objects in database X".
* A database that ran `DROP EXTENSION lolor` on an earlier version still has the rows, now pointing at a table that no longer exists, and no upgrade script will run there. Clean it by hand as superuser in that database: find the stale class OIDs with `SELECT DISTINCT classid FROM pg_shdepend WHERE dbid = (SELECT oid FROM pg_database WHERE datname = current_database()) AND classid NOT IN (SELECT oid FROM pg_class)`, then `DELETE FROM pg_shdepend WHERE dbid = <that dbid> AND classid IN (<those OIDs>)`.
* New helpers `lolor.check_orphans()` and `lolor.fix_orphans(new_owner)` for objects whose owner, grantee or grantor has been dropped. Objects in lolor storage cannot participate in `pg_shdepend`, so `DROP ROLE` does not notice them; `check_orphans()` lists them and which reference is dangling, and `fix_orphans()` reassigns dead owners, replacing them in the ACL as `REASSIGN OWNED` would so that grants they made survive, and drops entries that still name a missing role.
* Expanded test coverage: TAP tests for dump/restore, streaming and logical replication, and standby promotion; regression tests for `lo_lseek`, `lo_tell`, and `lo_truncate`.
* Security hardening: addressed Codacy/Flawfinder warnings.

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243 changes: 243 additions & 0 deletions expected/lolor.out
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Expand Up @@ -730,6 +730,247 @@ ERROR: 16 is outside the valid range for parameter "lolor.node" (0 .. 15)
SET lolor.node = 15;
SET lolor.node = 1;
--
-- Permission enforcement.
--
-- Objects in lolor storage have no catalog entry, so lolor cannot use the
-- syscache-backed owner and ACL checks and reimplements them against its own
-- tables. Exercise that path rather than assuming it matches core.
--
CREATE EXTENSION lolor;
CREATE ROLE lolor_alice;
CREATE ROLE lolor_bob;
-- Large object error messages quote the OID, which is generated and so
-- differs between runs. Report the message with digits masked instead.
CREATE FUNCTION lolor_expect_error(cmd text) RETURNS text AS $$
BEGIN
EXECUTE cmd;
RETURN 'unexpectedly succeeded';
EXCEPTION WHEN OTHERS THEN
RETURN regexp_replace(SQLERRM, '[0-9]+', 'NNN', 'g');
END
$$ LANGUAGE plpgsql;
SET ROLE lolor_alice;
SELECT lo_from_bytea(0, 'alice private data') AS alice_oid \gset
SELECT convert_from(lo_get(:alice_oid), 'UTF8') AS owner_can_read;
owner_can_read
--------------------
alice private data
(1 row)

RESET ROLE;
-- A different role gets nothing without a grant.
SET ROLE lolor_bob;
SELECT lolor_expect_error(format('SELECT lo_get(%s)', :alice_oid)) AS read_denied;
read_denied
----------------------------------------
permission denied for large object NNN
(1 row)

SELECT lolor_expect_error(format('SELECT lo_open(%s, 262144)', :alice_oid)) AS open_denied;
open_denied
----------------------------------------
permission denied for large object NNN
(1 row)

SELECT lolor_expect_error(format('SELECT lo_put(%s, 0, ''x'')', :alice_oid)) AS write_denied;
write_denied
----------------------------------------
permission denied for large object NNN
(1 row)

SELECT lolor_expect_error(format('SELECT lo_unlink(%s)', :alice_oid)) AS unlink_denied;
unlink_denied
-----------------------------------
must be owner of large object NNN
(1 row)

RESET ROLE;
-- The superuser bypasses the check, as in core.
SELECT convert_from(lo_get(:alice_oid), 'UTF8') AS superuser_can_read;
superuser_can_read
--------------------
alice private data
(1 row)

-- GRANT/ALTER on a large object act on pg_largeobject_metadata, where an
-- object in lolor storage has no row. This limitation is documented; assert
-- it so that a change in behaviour is noticed.
SELECT lolor_expect_error(
format('GRANT SELECT ON LARGE OBJECT %s TO lolor_bob', :alice_oid)) AS grant_unsupported;
grant_unsupported
---------------------------------
large object NNN does not exist
(1 row)

SELECT lolor_expect_error(
format('ALTER LARGE OBJECT %s OWNER TO lolor_bob', :alice_oid)) AS alter_unsupported;
alter_unsupported
---------------------------------
large object NNN does not exist
(1 row)

SELECT lo_unlink(:alice_oid);
lo_unlink
-----------
1
(1 row)

--
-- Objects in lolor storage are rows in ordinary tables and cannot participate
-- in pg_shdepend, so DROP ROLE does not notice that a role still owns one.
-- lolor.check_orphans() exists to make the consequence findable.
--
SET ROLE lolor_alice;
SELECT lo_from_bytea(0, 'owned by a role about to vanish') AS orphan_oid \gset
RESET ROLE;
SELECT count(*) AS orphans_before FROM lolor.check_orphans();
orphans_before
----------------
0
(1 row)

DROP ROLE lolor_alice;
SELECT count(*) AS orphans_after FROM lolor.check_orphans();
orphans_after
---------------
1
(1 row)

SELECT lo_unlink(:orphan_oid);
lo_unlink
-----------
1
(1 row)

SELECT count(*) AS orphans_cleared FROM lolor.check_orphans();
orphans_cleared
-----------------
0
(1 row)

--
-- fix_orphans() must behave like REASSIGN OWNED: grants the dead owner made
-- survive with the new owner as grantor, an entry the new owner already held
-- merges into its owner entry, and only entries that still name a missing
-- role are dropped. ACLs can only be set in native storage, so build them
-- there and migrate in.
--
CREATE ROLE lolor_dead_owner;
CREATE ROLE lolor_carol;
CREATE ROLE lolor_dave;
SELECT lolor.disable();
disable
---------
t
(1 row)

SET ROLE lolor_dead_owner;
SELECT lo_from_bytea(0, 'granted to bob') AS granted_oid \gset
GRANT SELECT ON LARGE OBJECT :granted_oid TO lolor_bob;
SELECT lo_from_bytea(0, 'grant chain') AS chain_oid \gset
GRANT SELECT ON LARGE OBJECT :chain_oid TO lolor_dave WITH GRANT OPTION;
SELECT lo_from_bytea(0, 'new owner already a grantee') AS merge_oid \gset
GRANT SELECT ON LARGE OBJECT :merge_oid TO lolor_carol;
RESET ROLE;
SET ROLE lolor_dave;
GRANT SELECT ON LARGE OBJECT :chain_oid TO lolor_bob;
RESET ROLE;
SELECT lolor.enable();
enable
--------
t
(1 row)

SELECT lolor.migrate_from_native();
NOTICE: migrated 12 large object(s) (12 data page(s)) from native to lolor storage
migrate_from_native
---------------------
12
(1 row)

DROP ROLE lolor_dead_owner;
SELECT role_kind, count(*) FROM lolor.check_orphans() GROUP BY 1 ORDER BY 1;
role_kind | count
-----------+-------
grantee | 3
grantor | 3
owner | 3
(3 rows)

SELECT lolor.fix_orphans('lolor_carol') AS objects_repaired;
objects_repaired
------------------
3
(1 row)

SELECT count(*) AS orphans_left FROM lolor.check_orphans();
orphans_left
--------------
0
(1 row)

-- Role OIDs vary per run, so compare the rebuilt ACLs by name
SELECT CASE m.oid WHEN :granted_oid THEN 'granted' WHEN :chain_oid THEN 'chain' ELSE 'merge' END AS obj,
pg_get_userbyid(m.lomowner) AS owner,
a.grantee::regrole::text AS grantee, a.grantor::regrole::text AS grantor, a.privilege_type
FROM lolor.pg_largeobject_metadata m, aclexplode(m.lomacl) a
WHERE m.oid IN (:granted_oid, :chain_oid, :merge_oid)
ORDER BY 1, 3, 4, 5;
obj | owner | grantee | grantor | privilege_type
---------+-------------+-------------+-------------+----------------
chain | lolor_carol | lolor_bob | lolor_dave | SELECT
chain | lolor_carol | lolor_carol | lolor_carol | SELECT
chain | lolor_carol | lolor_carol | lolor_carol | UPDATE
chain | lolor_carol | lolor_dave | lolor_carol | SELECT
granted | lolor_carol | lolor_bob | lolor_carol | SELECT
granted | lolor_carol | lolor_carol | lolor_carol | SELECT
granted | lolor_carol | lolor_carol | lolor_carol | UPDATE
merge | lolor_carol | lolor_carol | lolor_carol | SELECT
merge | lolor_carol | lolor_carol | lolor_carol | UPDATE
(9 rows)

-- The grantee kept access and the new owner has it
SET ROLE lolor_bob;
SELECT convert_from(lo_get(:granted_oid), 'UTF8') AS bob_still_reads;
bob_still_reads
-----------------
granted to bob
(1 row)

RESET ROLE;
SET ROLE lolor_carol;
SELECT convert_from(lo_get(:chain_oid), 'UTF8') AS new_owner_reads;
new_owner_reads
-----------------
grant chain
(1 row)

RESET ROLE;
SELECT lo_unlink(:granted_oid);
lo_unlink
-----------
1
(1 row)

SELECT lo_unlink(:chain_oid);
lo_unlink
-----------
1
(1 row)

SELECT lo_unlink(:merge_oid);
lo_unlink
-----------
1
(1 row)

DROP ROLE lolor_carol;
DROP ROLE lolor_dave;
DROP ROLE lolor_bob;
DROP FUNCTION lolor_expect_error(text);
DROP EXTENSION lolor;
NOTICE: migrated 9 large object(s) from lolor to native storage
--
-- 64-bit interface and page-boundary I/O. lo_put(), lo_tell64() and
-- lo_truncate64() had no coverage.
--
Expand Down Expand Up @@ -1050,6 +1291,8 @@ SELECT lo_unlink(:multi_oid);
--
SELECT lo_get(0);
ERROR: large object 0 does not exist
SELECT lo_unlink(0);
ERROR: large object 0 does not exist
BEGIN;
SELECT lo_open(0, 262144);
ERROR: large object 0 does not exist
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108 changes: 108 additions & 0 deletions lolor--1.2.2--1.3.0.sql
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Expand Up @@ -47,6 +47,114 @@ BEGIN
END;
$$;

/*
* Large objects in lolor storage that refer to a role which no longer exists,
* as owner, grantee or grantor.
*
* Objects in lolor storage are rows in ordinary tables, so they cannot
* participate in pg_shdepend: DROP ROLE will not notice them the way it
* notices native large objects. That is inherent to storing them outside the
* catalogs; this function makes the consequence findable, and fix_orphans()
* repairs it. Joins pg_roles rather than pg_authid so that a grantee of
* EXECUTE can actually run it.
*/
CREATE FUNCTION lolor.check_orphans()
RETURNS TABLE (loid oid, role_oid oid, role_kind text) AS $$
SELECT m.oid, m.lomowner, 'owner'
FROM lolor.pg_largeobject_metadata m
WHERE NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = m.lomowner)
UNION
SELECT m.oid, a.grantee, 'grantee'
FROM lolor.pg_largeobject_metadata m, pg_catalog.aclexplode(m.lomacl) a
WHERE a.grantee <> 0
AND NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = a.grantee)
UNION
SELECT m.oid, a.grantor, 'grantor'
FROM lolor.pg_largeobject_metadata m, pg_catalog.aclexplode(m.lomacl) a
WHERE NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = a.grantor)
ORDER BY 1, 3, 2
$$ LANGUAGE sql STABLE;

REVOKE ALL ON FUNCTION lolor.check_orphans() FROM PUBLIC;

/*
* Repair what check_orphans() reports. Objects whose owner is gone go to
* new_owner, and the ACL is rebuilt the way core's aclnewowner() does it: the
* old owner is replaced by new_owner wherever it appears as grantee or
* grantor, entries that then coincide are merged, and only entries that still
* name a missing role are dropped. Grants the old owner made therefore
* survive, as they do under REASSIGN OWNED. Returns the number of objects
* changed.
*
* One UPDATE is essential: the ACL rewrite has to see the old owner, and a
* separate UPDATE of lomowner would already have lost it.
*/
CREATE FUNCTION lolor.fix_orphans(new_owner regrole)
RETURNS bigint AS $$
DECLARE
fixed bigint;
BEGIN
IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = current_user AND rolsuper) THEN
RAISE EXCEPTION 'must be superuser to repair orphaned large objects';
END IF;

WITH o AS (
SELECT m.oid, m.lomowner AS old_owner, m.lomacl,
NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = m.lomowner) AS owner_dead
FROM lolor.pg_largeobject_metadata m)
UPDATE lolor.pg_largeobject_metadata m
SET lomowner = CASE WHEN o.owner_dead THEN new_owner::oid ELSE m.lomowner END,
-- aclexplode() yields one row per privilege. Substitute the owner,
-- regroup so coinciding entries merge, then rebuild with
-- makeaclitem(). An empty result is NULL, meaning default
-- privileges.
lomacl = (
SELECT array_agg(pg_catalog.makeaclitem(s.grantee, s.grantor, s.privs, s.is_grantable)
ORDER BY s.grantee, s.grantor, s.is_grantable)
FROM (SELECT CASE WHEN o.owner_dead AND a.grantee = o.old_owner
THEN new_owner::oid ELSE a.grantee END AS grantee,
CASE WHEN o.owner_dead AND a.grantor = o.old_owner
THEN new_owner::oid ELSE a.grantor END AS grantor,
a.is_grantable,
string_agg(DISTINCT a.privilege_type, ',') AS privs
FROM pg_catalog.aclexplode(o.lomacl) a
GROUP BY 1, 2, 3) s
WHERE (s.grantee = 0
OR EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = s.grantee))
AND EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = s.grantor))
FROM o
WHERE m.oid = o.oid
AND (o.owner_dead
OR EXISTS (SELECT 1 FROM pg_catalog.aclexplode(o.lomacl) a
WHERE (a.grantee <> 0
AND NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = a.grantee))
OR NOT EXISTS (SELECT 1 FROM pg_catalog.pg_roles r WHERE r.oid = a.grantor)));
GET DIAGNOSTICS fixed = ROW_COUNT;

RETURN fixed;
END;
$$ LANGUAGE plpgsql VOLATILE;

REVOKE ALL ON FUNCTION lolor.fix_orphans(regrole) FROM PUBLIC;

/*
* Remove the bogus pg_shdepend rows left by earlier versions.
*
* Through 1.2.2, creating a large object recorded a pg_shdepend row whose
* classId was the OID of lolor.pg_largeobject -- an ordinary table, not a
* catalog the dependency machinery can describe. DROP ROLE on any role that
* had created one failed with "unrecognized object class", and the rows were
* never removed.
*
* pg_shdepend is shared across the cluster, so restrict the delete to this
* database: the same classId in another database is an unrelated relation.
*/
DELETE FROM pg_catalog.pg_shdepend
WHERE dbid = (SELECT oid FROM pg_catalog.pg_database
WHERE datname = current_database())
AND classid IN ('lolor.pg_largeobject'::regclass,
'lolor.pg_largeobject_metadata'::regclass);

/*
* lolor.migrate_from_native()
*
Expand Down
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