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Simplify permissions for LOCK TABLE.

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The prior behavior was confusing and hard to document. For instance,
if you had UPDATE privileges, you could lock a table in any lock mode
except ACCESS SHARE mode.

Now, if granted a privilege to lock at a given mode, one also has
privileges to lock at a less-conflicting mode. MAINTAIN, UPDATE,
DELETE, and TRUNCATE privileges allow any lock mode. INSERT privileges
allow ROW EXCLUSIVE (or below). SELECT privileges allow ACCESS SHARE.

Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/9550c76535404a83156252b25a11babb4792ea1e.camel%40j-davis.com
This commit is contained in:
Jeff Davis
2023-01-13 14:14:54 -08:00
parent b7ae039536
commit c44f6334ca
4 changed files with 81 additions and 93 deletions
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18
src/backend/commands/lockcmds.c
View File

@ -292,16 +292,16 @@ LockTableAclCheck(Oid reloid, LOCKMODE lockmode, Oid userid)
AclResult aclresult;
AclMode aclmask;
/* Verify adequate privilege */
if (lockmode == AccessShareLock)
aclmask = ACL_SELECT;
else if (lockmode == RowExclusiveLock)
aclmask = ACL_INSERT | ACL_UPDATE | ACL_DELETE | ACL_TRUNCATE;
else
aclmask = ACL_UPDATE | ACL_DELETE | ACL_TRUNCATE;
/* any of these privileges permit any lock mode */
aclmask = ACL_MAINTAIN | ACL_UPDATE | ACL_DELETE | ACL_TRUNCATE;
/* MAINTAIN privilege allows all lock modes */
aclmask |= ACL_MAINTAIN;
/* SELECT privileges also permit ACCESS SHARE and below */
if (lockmode <= AccessShareLock)
aclmask |= ACL_SELECT;
/* INSERT privileges also permit ROW EXCLUSIVE and below */
if (lockmode <= RowExclusiveLock)
aclmask |= ACL_INSERT;
aclresult = pg_class_aclcheck(reloid, userid, aclmask);