Fix bugs in manipulation of large objects.

In v16 and up (since commit afbfc0298), large object ownership
checking has been broken because object_ownercheck() didn't take care
of the discrepancy between our object-address representation of large
objects (classId == LargeObjectRelationId) and the catalog where their
ownership info is actually stored (LargeObjectMetadataRelationId).
This resulted in failures such as "unrecognized class ID: 2613"
when trying to update blob properties as a non-superuser.

Poking around for related bugs, I found that AlterObjectOwner_internal
would pass the wrong classId to the PostAlterHook in the no-op code
path where the large object already has the desired owner.  Also,
recordExtObjInitPriv checked for the wrong classId; that bug is only
latent because the stanza is dead code anyway, but as long as we're
carrying it around it should be less wrong.  These bugs are quite old.

In HEAD, we can reduce the scope for future bugs of this ilk by
changing AlterObjectOwner_internal's API to let the translation happen
inside that function, rather than requiring callers to know about it.

A more bulletproof fix, perhaps, would be to start using
LargeObjectMetadataRelationId as the dependency and object-address
classId for blobs.  However that has substantial risk of breaking
third-party code; even within our own code, it'd create hassles
for pg_dump which would have to cope with a version-dependent
representation.  For now, keep the status quo.

Discussion: https://postgr.es/m/2650449.1702497209@sss.pgh.pa.us

diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index d1f5dcd8bed1ea7b1e304c8c2cce316328f5611d..a2aad09e6a046d7bdb20ef46be38472376fd635e 100644 (file)
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -3967,9 +3967,14 @@ object_ownercheck(Oid classid, Oid objectid, Oid roleid)
    if (superuser_arg(roleid))
        return true;
 
+   /* For large objects, the catalog to consult is pg_largeobject_metadata */
+   if (classid == LargeObjectRelationId)
+       classid = LargeObjectMetadataRelationId;
+
    cacheid = get_object_catcache_oid(classid);
    if (cacheid != -1)
    {
+       /* we can get the object's tuple from the syscache */
        HeapTuple   tuple;
 
        tuple = SearchSysCache1(cacheid, ObjectIdGetDatum(objectid));
@@ -3986,7 +3991,6 @@ object_ownercheck(Oid classid, Oid objectid, Oid roleid)
    else
    {
        /* for catalogs without an appropriate syscache */
-
        Relation    rel;
        ScanKeyData entry[1];
        SysScanDesc scan;
@@ -4306,9 +4310,9 @@ recordExtObjInitPriv(Oid objoid, Oid classoid)
 
        ReleaseSysCache(tuple);
    }
-   /* pg_largeobject_metadata */
-   else if (classoid == LargeObjectMetadataRelationId)
+   else if (classoid == LargeObjectRelationId)
    {
+       /* For large objects, we must consult pg_largeobject_metadata */
        Datum       aclDatum;
        bool        isNull;
        HeapTuple   tuple;

diff --git a/src/backend/catalog/pg_shdepend.c b/src/backend/catalog/pg_shdepend.c
index 91c7f3426f95cb19ea1187e0f6b995faf4a58f82..ea41d9b7502a57c4257ac2b442857c5587096452 100644 (file)
--- a/src/backend/catalog/pg_shdepend.c
+++ b/src/backend/catalog/pg_shdepend.c
@@ -1618,6 +1618,10 @@ shdepReassignOwned(List *roleids, Oid newrole)
                        Oid         classId = sdepForm->classid;
                        Relation    catalog;
 
+                       /*
+                        * For large objects, the catalog to modify is
+                        * pg_largeobject_metadata
+                        */
                        if (classId == LargeObjectRelationId)
                            classId = LargeObjectMetadataRelationId;
 

diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index e95dc31bde3582c10f20ffdadcf162ecb224e2bf..cbe02853b046d4785bef0e98d0b915e2df72f839 100644 (file)
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -929,9 +929,8 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
                classId = address.classId;
 
                /*
-                * XXX - get_object_address returns Oid of pg_largeobject
-                * catalog for OBJECT_LARGEOBJECT because of historical
-                * reasons.  Fix up it here.
+                * For large objects, the catalog to modify is
+                * pg_largeobject_metadata
                 */
                if (classId == LargeObjectRelationId)
                    classId = LargeObjectMetadataRelationId;
@@ -1075,9 +1074,14 @@ AlterObjectOwner_internal(Relation rel, Oid objectId, Oid new_ownerId)
        /* Perform actual update */
        CatalogTupleUpdate(rel, &newtup->t_self, newtup);
 
-       /* Update owner dependency reference */
+       /*
+        * Update owner dependency reference.  When working on a large object,
+        * we have to translate back to the OID conventionally used for LOs'
+        * classId.
+        */
        if (classId == LargeObjectMetadataRelationId)
            classId = LargeObjectRelationId;
+
        changeDependencyOnOwner(classId, objectId, new_ownerId);
 
        /* Release memory */
@@ -1085,6 +1089,16 @@ AlterObjectOwner_internal(Relation rel, Oid objectId, Oid new_ownerId)
        pfree(nulls);
        pfree(replaces);
    }
+   else
+   {
+       /*
+        * No need to change anything.  But when working on a large object, we
+        * have to translate back to the OID conventionally used for LOs'
+        * classId, or the post-alter hook (if any) will get confused.
+        */
+       if (classId == LargeObjectMetadataRelationId)
+           classId = LargeObjectRelationId;
+   }
 
    InvokeObjectPostAlterHook(classId, objectId, 0);
 }

diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
index d189044a4fc2cc916178963011112209ba9a8d9e..230c65753205ba234c15dfaddc01476ca43d2a15 100644 (file)
--- a/src/backend/libpq/be-fsstubs.c
+++ b/src/backend/libpq/be-fsstubs.c
@@ -43,7 +43,7 @@
 #include <unistd.h>
 
 #include "access/xact.h"
-#include "catalog/pg_largeobject_metadata.h"
+#include "catalog/pg_largeobject.h"
 #include "libpq/be-fsstubs.h"
 #include "libpq/libpq-fs.h"
 #include "miscadmin.h"
@@ -323,7 +323,7 @@ be_lo_unlink(PG_FUNCTION_ARGS)
     * relevant FDs.
     */
    if (!lo_compat_privileges &&
-       !object_ownercheck(LargeObjectMetadataRelationId, lobjId, GetUserId()))
+       !object_ownercheck(LargeObjectRelationId, lobjId, GetUserId()))
        ereport(ERROR,
                (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
                 errmsg("must be owner of large object %u", lobjId)));

diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index 84e543e731091c5b964d154baeb23ad503e7a5e5..cab47f82fb667b56e594e50bf2ac80e9f45995bd 100644 (file)
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -221,11 +221,10 @@ inv_create(Oid lobjId)
    /*
     * dependency on the owner of largeobject
     *
-    * The reason why we use LargeObjectRelationId instead of
-    * LargeObjectMetadataRelationId here is to provide backward compatibility
-    * to the applications which utilize a knowledge about internal layout of
-    * system catalogs. OID of pg_largeobject_metadata and loid of
-    * pg_largeobject are same value, so there are no actual differences here.
+    * Note that LO dependencies are recorded using classId
+    * LargeObjectRelationId for backwards-compatibility reasons.  Using
+    * LargeObjectMetadataRelationId instead would simplify matters for the
+    * backend, but it'd complicate pg_dump and possibly break other clients.
     */
    recordDependencyOnOwner(LargeObjectRelationId,
                            lobjId_new, GetUserId());

diff --git a/src/test/regress/expected/largeobject.out b/src/test/regress/expected/largeobject.out
index bdcede6728e8acd0d248c0d4dcac41fac1b5a825..4921dd79aeec1716ceaba9334612dfefd8575146 100644 (file)
--- a/src/test/regress/expected/largeobject.out
+++ b/src/test/regress/expected/largeobject.out
@@ -6,7 +6,7 @@
 \getenv abs_builddir PG_ABS_BUILDDIR
 -- ensure consistent test output regardless of the default bytea format
 SET bytea_output TO escape;
--- Test ALTER LARGE OBJECT OWNER, GRANT, COMMENT
+-- Test ALTER LARGE OBJECT OWNER
 CREATE ROLE regress_lo_user;
 SELECT lo_create(42);
  lo_create 
@@ -15,8 +15,11 @@ SELECT lo_create(42);
 (1 row)
 
 ALTER LARGE OBJECT 42 OWNER TO regress_lo_user;
+-- Test GRANT, COMMENT as non-superuser
+SET SESSION AUTHORIZATION regress_lo_user;
 GRANT SELECT ON LARGE OBJECT 42 TO public;
 COMMENT ON LARGE OBJECT 42 IS 'the ultimate answer';
+RESET SESSION AUTHORIZATION;
 -- Test psql's \lo_list et al (we assume no other LOs exist yet)
 \lo_list
                Large objects

diff --git a/src/test/regress/expected/largeobject_1.out b/src/test/regress/expected/largeobject_1.out
index d700910c35962455132b018a73129b6120ad3df8..7172ddb39bb293418e209d5c4f2128920520eefb 100644 (file)
--- a/src/test/regress/expected/largeobject_1.out
+++ b/src/test/regress/expected/largeobject_1.out
@@ -6,7 +6,7 @@
 \getenv abs_builddir PG_ABS_BUILDDIR
 -- ensure consistent test output regardless of the default bytea format
 SET bytea_output TO escape;
--- Test ALTER LARGE OBJECT OWNER, GRANT, COMMENT
+-- Test ALTER LARGE OBJECT OWNER
 CREATE ROLE regress_lo_user;
 SELECT lo_create(42);
  lo_create 
@@ -15,8 +15,11 @@ SELECT lo_create(42);
 (1 row)
 
 ALTER LARGE OBJECT 42 OWNER TO regress_lo_user;
+-- Test GRANT, COMMENT as non-superuser
+SET SESSION AUTHORIZATION regress_lo_user;
 GRANT SELECT ON LARGE OBJECT 42 TO public;
 COMMENT ON LARGE OBJECT 42 IS 'the ultimate answer';
+RESET SESSION AUTHORIZATION;
 -- Test psql's \lo_list et al (we assume no other LOs exist yet)
 \lo_list
                Large objects

diff --git a/src/test/regress/sql/largeobject.sql b/src/test/regress/sql/largeobject.sql
index 800e4fcc6a2b2874207b60b8b99bb12475274fa6..a4aee02e3a4ea7c369d7d684354eb8f9627f568f 100644 (file)
--- a/src/test/regress/sql/largeobject.sql
+++ b/src/test/regress/sql/largeobject.sql
@@ -9,13 +9,19 @@
 -- ensure consistent test output regardless of the default bytea format
 SET bytea_output TO escape;
 
--- Test ALTER LARGE OBJECT OWNER, GRANT, COMMENT
+-- Test ALTER LARGE OBJECT OWNER
 CREATE ROLE regress_lo_user;
 SELECT lo_create(42);
 ALTER LARGE OBJECT 42 OWNER TO regress_lo_user;
+
+-- Test GRANT, COMMENT as non-superuser
+SET SESSION AUTHORIZATION regress_lo_user;
+
 GRANT SELECT ON LARGE OBJECT 42 TO public;
 COMMENT ON LARGE OBJECT 42 IS 'the ultimate answer';
 
+RESET SESSION AUTHORIZATION;
+
 -- Test psql's \lo_list et al (we assume no other LOs exist yet)
 \lo_list
 \lo_list+