1/*-------------------------------------------------------------------------
2 *
3 * schemacmds.c
4 * schema creation/manipulation commands
5 *
6 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * src/backend/commands/schemacmds.c
12 *
13 *-------------------------------------------------------------------------
14 */
15#include "postgres.h"
16
17#include "access/htup_details.h"
18#include "access/table.h"
19#include "access/xact.h"
20#include "catalog/catalog.h"
21#include "catalog/dependency.h"
22#include "catalog/indexing.h"
23#include "catalog/namespace.h"
24#include "catalog/pg_authid.h"
25#include "catalog/objectaccess.h"
26#include "catalog/pg_namespace.h"
27#include "commands/dbcommands.h"
28#include "commands/event_trigger.h"
29#include "commands/schemacmds.h"
30#include "miscadmin.h"
31#include "parser/parse_utilcmd.h"
32#include "tcop/utility.h"
33#include "utils/acl.h"
34#include "utils/builtins.h"
35#include "utils/rel.h"
36#include "utils/syscache.h"
37
38
39static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId);
40
41/*
42 * CREATE SCHEMA
43 *
44 * Note: caller should pass in location information for the whole
45 * CREATE SCHEMA statement, which in turn we pass down as the location
46 * of the component commands. This comports with our general plan of
47 * reporting location/len for the whole command even when executing
48 * a subquery.
49 */
50Oid
51CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString,
52 int stmt_location, int stmt_len)
53{
54 const char *schemaName = stmt->schemaname;
55 Oid namespaceId;
56 OverrideSearchPath *overridePath;
57 List *parsetree_list;
58 ListCell *parsetree_item;
59 Oid owner_uid;
60 Oid saved_uid;
61 int save_sec_context;
62 AclResult aclresult;
63 ObjectAddress address;
64
65 GetUserIdAndSecContext(&saved_uid, &save_sec_context);
66
67 /*
68 * Who is supposed to own the new schema?
69 */
70 if (stmt->authrole)
71 owner_uid = get_rolespec_oid(stmt->authrole, false);
72 else
73 owner_uid = saved_uid;
74
75 /* fill schema name with the user name if not specified */
76 if (!schemaName)
77 {
78 HeapTuple tuple;
79
80 tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(owner_uid));
81 if (!HeapTupleIsValid(tuple))
82 elog(ERROR, "cache lookup failed for role %u", owner_uid);
83 schemaName =
84 pstrdup(NameStr(((Form_pg_authid) GETSTRUCT(tuple))->rolname));
85 ReleaseSysCache(tuple);
86 }
87
88 /*
89 * To create a schema, must have schema-create privilege on the current
90 * database and must be able to become the target role (this does not
91 * imply that the target role itself must have create-schema privilege).
92 * The latter provision guards against "giveaway" attacks. Note that a
93 * superuser will always have both of these privileges a fortiori.
94 */
95 aclresult = pg_database_aclcheck(MyDatabaseId, saved_uid, ACL_CREATE);
96 if (aclresult != ACLCHECK_OK)
97 aclcheck_error(aclresult, OBJECT_DATABASE,
98 get_database_name(MyDatabaseId));
99
100 check_is_member_of_role(saved_uid, owner_uid);
101
102 /* Additional check to protect reserved schema names */
103 if (!allowSystemTableMods && IsReservedName(schemaName))
104 ereport(ERROR,
105 (errcode(ERRCODE_RESERVED_NAME),
106 errmsg("unacceptable schema name \"%s\"", schemaName),
107 errdetail("The prefix \"pg_\" is reserved for system schemas.")));
108
109 /*
110 * If if_not_exists was given and the schema already exists, bail out.
111 * (Note: we needn't check this when not if_not_exists, because
112 * NamespaceCreate will complain anyway.) We could do this before making
113 * the permissions checks, but since CREATE TABLE IF NOT EXISTS makes its
114 * creation-permission check first, we do likewise.
115 */
116 if (stmt->if_not_exists &&
117 SearchSysCacheExists1(NAMESPACENAME, PointerGetDatum(schemaName)))
118 {
119 ereport(NOTICE,
120 (errcode(ERRCODE_DUPLICATE_SCHEMA),
121 errmsg("schema \"%s\" already exists, skipping",
122 schemaName)));
123 return InvalidOid;
124 }
125
126 /*
127 * If the requested authorization is different from the current user,
128 * temporarily set the current user so that the object(s) will be created
129 * with the correct ownership.
130 *
131 * (The setting will be restored at the end of this routine, or in case of
132 * error, transaction abort will clean things up.)
133 */
134 if (saved_uid != owner_uid)
135 SetUserIdAndSecContext(owner_uid,
136 save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
137
138 /* Create the schema's namespace */
139 namespaceId = NamespaceCreate(schemaName, owner_uid, false);
140
141 /* Advance cmd counter to make the namespace visible */
142 CommandCounterIncrement();
143
144 /*
145 * Temporarily make the new namespace be the front of the search path, as
146 * well as the default creation target namespace. This will be undone at
147 * the end of this routine, or upon error.
148 */
149 overridePath = GetOverrideSearchPath(CurrentMemoryContext);
150 overridePath->schemas = lcons_oid(namespaceId, overridePath->schemas);
151 /* XXX should we clear overridePath->useTemp? */
152 PushOverrideSearchPath(overridePath);
153
154 /*
155 * Report the new schema to possibly interested event triggers. Note we
156 * must do this here and not in ProcessUtilitySlow because otherwise the
157 * objects created below are reported before the schema, which would be
158 * wrong.
159 */
160 ObjectAddressSet(address, NamespaceRelationId, namespaceId);
161 EventTriggerCollectSimpleCommand(address, InvalidObjectAddress,
162 (Node *) stmt);
163
164 /*
165 * Examine the list of commands embedded in the CREATE SCHEMA command, and
166 * reorganize them into a sequentially executable order with no forward
167 * references. Note that the result is still a list of raw parsetrees ---
168 * we cannot, in general, run parse analysis on one statement until we
169 * have actually executed the prior ones.
170 */
171 parsetree_list = transformCreateSchemaStmt(stmt);
172
173 /*
174 * Execute each command contained in the CREATE SCHEMA. Since the grammar
175 * allows only utility commands in CREATE SCHEMA, there is no need to pass
176 * them through parse_analyze() or the rewriter; we can just hand them
177 * straight to ProcessUtility.
178 */
179 foreach(parsetree_item, parsetree_list)
180 {
181 Node *stmt = (Node *) lfirst(parsetree_item);
182 PlannedStmt *wrapper;
183
184 /* need to make a wrapper PlannedStmt */
185 wrapper = makeNode(PlannedStmt);
186 wrapper->commandType = CMD_UTILITY;
187 wrapper->canSetTag = false;
188 wrapper->utilityStmt = stmt;
189 wrapper->stmt_location = stmt_location;
190 wrapper->stmt_len = stmt_len;
191
192 /* do this step */
193 ProcessUtility(wrapper,
194 queryString,
195 PROCESS_UTILITY_SUBCOMMAND,
196 NULL,
197 NULL,
198 None_Receiver,
199 NULL);
200
201 /* make sure later steps can see the object created here */
202 CommandCounterIncrement();
203 }
204
205 /* Reset search path to normal state */
206 PopOverrideSearchPath();
207
208 /* Reset current user and security context */
209 SetUserIdAndSecContext(saved_uid, save_sec_context);
210
211 return namespaceId;
212}
213
214/*
215 * Guts of schema deletion.
216 */
217void
218RemoveSchemaById(Oid schemaOid)
219{
220 Relation relation;
221 HeapTuple tup;
222
223 relation = table_open(NamespaceRelationId, RowExclusiveLock);
224
225 tup = SearchSysCache1(NAMESPACEOID,
226 ObjectIdGetDatum(schemaOid));
227 if (!HeapTupleIsValid(tup)) /* should not happen */
228 elog(ERROR, "cache lookup failed for namespace %u", schemaOid);
229
230 CatalogTupleDelete(relation, &tup->t_self);
231
232 ReleaseSysCache(tup);
233
234 table_close(relation, RowExclusiveLock);
235}
236
237
238/*
239 * Rename schema
240 */
241ObjectAddress
242RenameSchema(const char *oldname, const char *newname)
243{
244 Oid nspOid;
245 HeapTuple tup;
246 Relation rel;
247 AclResult aclresult;
248 ObjectAddress address;
249 Form_pg_namespace nspform;
250
251 rel = table_open(NamespaceRelationId, RowExclusiveLock);
252
253 tup = SearchSysCacheCopy1(NAMESPACENAME, CStringGetDatum(oldname));
254 if (!HeapTupleIsValid(tup))
255 ereport(ERROR,
256 (errcode(ERRCODE_UNDEFINED_SCHEMA),
257 errmsg("schema \"%s\" does not exist", oldname)));
258
259 nspform = (Form_pg_namespace) GETSTRUCT(tup);
260 nspOid = nspform->oid;
261
262 /* make sure the new name doesn't exist */
263 if (OidIsValid(get_namespace_oid(newname, true)))
264 ereport(ERROR,
265 (errcode(ERRCODE_DUPLICATE_SCHEMA),
266 errmsg("schema \"%s\" already exists", newname)));
267
268 /* must be owner */
269 if (!pg_namespace_ownercheck(nspOid, GetUserId()))
270 aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SCHEMA,
271 oldname);
272
273 /* must have CREATE privilege on database */
274 aclresult = pg_database_aclcheck(MyDatabaseId, GetUserId(), ACL_CREATE);
275 if (aclresult != ACLCHECK_OK)
276 aclcheck_error(aclresult, OBJECT_DATABASE,
277 get_database_name(MyDatabaseId));
278
279 if (!allowSystemTableMods && IsReservedName(newname))
280 ereport(ERROR,
281 (errcode(ERRCODE_RESERVED_NAME),
282 errmsg("unacceptable schema name \"%s\"", newname),
283 errdetail("The prefix \"pg_\" is reserved for system schemas.")));
284
285 /* rename */
286 namestrcpy(&nspform->nspname, newname);
287 CatalogTupleUpdate(rel, &tup->t_self, tup);
288
289 InvokeObjectPostAlterHook(NamespaceRelationId, nspOid, 0);
290
291 ObjectAddressSet(address, NamespaceRelationId, nspOid);
292
293 table_close(rel, NoLock);
294 heap_freetuple(tup);
295
296 return address;
297}
298
299void
300AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
301{
302 HeapTuple tup;
303 Relation rel;
304
305 rel = table_open(NamespaceRelationId, RowExclusiveLock);
306
307 tup = SearchSysCache1(NAMESPACEOID, ObjectIdGetDatum(oid));
308 if (!HeapTupleIsValid(tup))
309 elog(ERROR, "cache lookup failed for schema %u", oid);
310
311 AlterSchemaOwner_internal(tup, rel, newOwnerId);
312
313 ReleaseSysCache(tup);
314
315 table_close(rel, RowExclusiveLock);
316}
317
318
319/*
320 * Change schema owner
321 */
322ObjectAddress
323AlterSchemaOwner(const char *name, Oid newOwnerId)
324{
325 Oid nspOid;
326 HeapTuple tup;
327 Relation rel;
328 ObjectAddress address;
329 Form_pg_namespace nspform;
330
331 rel = table_open(NamespaceRelationId, RowExclusiveLock);
332
333 tup = SearchSysCache1(NAMESPACENAME, CStringGetDatum(name));
334 if (!HeapTupleIsValid(tup))
335 ereport(ERROR,
336 (errcode(ERRCODE_UNDEFINED_SCHEMA),
337 errmsg("schema \"%s\" does not exist", name)));
338
339 nspform = (Form_pg_namespace) GETSTRUCT(tup);
340 nspOid = nspform->oid;
341
342 AlterSchemaOwner_internal(tup, rel, newOwnerId);
343
344 ObjectAddressSet(address, NamespaceRelationId, nspOid);
345
346 ReleaseSysCache(tup);
347
348 table_close(rel, RowExclusiveLock);
349
350 return address;
351}
352
353static void
354AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId)
355{
356 Form_pg_namespace nspForm;
357
358 Assert(tup->t_tableOid == NamespaceRelationId);
359 Assert(RelationGetRelid(rel) == NamespaceRelationId);
360
361 nspForm = (Form_pg_namespace) GETSTRUCT(tup);
362
363 /*
364 * If the new owner is the same as the existing owner, consider the
365 * command to have succeeded. This is for dump restoration purposes.
366 */
367 if (nspForm->nspowner != newOwnerId)
368 {
369 Datum repl_val[Natts_pg_namespace];
370 bool repl_null[Natts_pg_namespace];
371 bool repl_repl[Natts_pg_namespace];
372 Acl *newAcl;
373 Datum aclDatum;
374 bool isNull;
375 HeapTuple newtuple;
376 AclResult aclresult;
377
378 /* Otherwise, must be owner of the existing object */
379 if (!pg_namespace_ownercheck(nspForm->oid, GetUserId()))
380 aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_SCHEMA,
381 NameStr(nspForm->nspname));
382
383 /* Must be able to become new owner */
384 check_is_member_of_role(GetUserId(), newOwnerId);
385
386 /*
387 * must have create-schema rights
388 *
389 * NOTE: This is different from other alter-owner checks in that the
390 * current user is checked for create privileges instead of the
391 * destination owner. This is consistent with the CREATE case for
392 * schemas. Because superusers will always have this right, we need
393 * no special case for them.
394 */
395 aclresult = pg_database_aclcheck(MyDatabaseId, GetUserId(),
396 ACL_CREATE);
397 if (aclresult != ACLCHECK_OK)
398 aclcheck_error(aclresult, OBJECT_DATABASE,
399 get_database_name(MyDatabaseId));
400
401 memset(repl_null, false, sizeof(repl_null));
402 memset(repl_repl, false, sizeof(repl_repl));
403
404 repl_repl[Anum_pg_namespace_nspowner - 1] = true;
405 repl_val[Anum_pg_namespace_nspowner - 1] = ObjectIdGetDatum(newOwnerId);
406
407 /*
408 * Determine the modified ACL for the new owner. This is only
409 * necessary when the ACL is non-null.
410 */
411 aclDatum = SysCacheGetAttr(NAMESPACENAME, tup,
412 Anum_pg_namespace_nspacl,
413 &isNull);
414 if (!isNull)
415 {
416 newAcl = aclnewowner(DatumGetAclP(aclDatum),
417 nspForm->nspowner, newOwnerId);
418 repl_repl[Anum_pg_namespace_nspacl - 1] = true;
419 repl_val[Anum_pg_namespace_nspacl - 1] = PointerGetDatum(newAcl);
420 }
421
422 newtuple = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null, repl_repl);
423
424 CatalogTupleUpdate(rel, &newtuple->t_self, newtuple);
425
426 heap_freetuple(newtuple);
427
428 /* Update owner dependency reference */
429 changeDependencyOnOwner(NamespaceRelationId, nspForm->oid,
430 newOwnerId);
431 }
432
433 InvokeObjectPostAlterHook(NamespaceRelationId,
434 nspForm->oid, 0);
435}
436