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schemacmds.c
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1 /*-------------------------------------------------------------------------
2  *
3  * schemacmds.c
4  * schema creation/manipulation commands
5  *
6  * Portions Copyright (c) 1996-2020, 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/objectaccess.h"
25 #include "catalog/pg_authid.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 static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId);
39 
40 /*
41  * CREATE SCHEMA
42  *
43  * Note: caller should pass in location information for the whole
44  * CREATE SCHEMA statement, which in turn we pass down as the location
45  * of the component commands. This comports with our general plan of
46  * reporting location/len for the whole command even when executing
47  * a subquery.
48  */
49 Oid
50 CreateSchemaCommand(CreateSchemaStmt *stmt, const char *queryString,
51  int stmt_location, int stmt_len)
52 {
53  const char *schemaName = stmt->schemaname;
54  Oid namespaceId;
55  OverrideSearchPath *overridePath;
56  List *parsetree_list;
57  ListCell *parsetree_item;
58  Oid owner_uid;
59  Oid saved_uid;
60  int save_sec_context;
61  AclResult aclresult;
62  ObjectAddress address;
63 
64  GetUserIdAndSecContext(&saved_uid, &save_sec_context);
65 
66  /*
67  * Who is supposed to own the new schema?
68  */
69  if (stmt->authrole)
70  owner_uid = get_rolespec_oid(stmt->authrole, false);
71  else
72  owner_uid = saved_uid;
73 
74  /* fill schema name with the user name if not specified */
75  if (!schemaName)
76  {
77  HeapTuple tuple;
78 
79  tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(owner_uid));
80  if (!HeapTupleIsValid(tuple))
81  elog(ERROR, "cache lookup failed for role %u", owner_uid);
82  schemaName =
84  ReleaseSysCache(tuple);
85  }
86 
87  /*
88  * To create a schema, must have schema-create privilege on the current
89  * database and must be able to become the target role (this does not
90  * imply that the target role itself must have create-schema privilege).
91  * The latter provision guards against "giveaway" attacks. Note that a
92  * superuser will always have both of these privileges a fortiori.
93  */
94  aclresult = pg_database_aclcheck(MyDatabaseId, saved_uid, ACL_CREATE);
95  if (aclresult != ACLCHECK_OK)
98 
99  check_is_member_of_role(saved_uid, owner_uid);
100 
101  /* Additional check to protect reserved schema names */
102  if (!allowSystemTableMods && IsReservedName(schemaName))
103  ereport(ERROR,
104  (errcode(ERRCODE_RESERVED_NAME),
105  errmsg("unacceptable schema name \"%s\"", schemaName),
106  errdetail("The prefix \"pg_\" is reserved for system schemas.")));
107 
108  /*
109  * If if_not_exists was given and the schema already exists, bail out.
110  * (Note: we needn't check this when not if_not_exists, because
111  * NamespaceCreate will complain anyway.) We could do this before making
112  * the permissions checks, but since CREATE TABLE IF NOT EXISTS makes its
113  * creation-permission check first, we do likewise.
114  */
115  if (stmt->if_not_exists &&
117  {
118  ereport(NOTICE,
119  (errcode(ERRCODE_DUPLICATE_SCHEMA),
120  errmsg("schema \"%s\" already exists, skipping",
121  schemaName)));
122  return InvalidOid;
123  }
124 
125  /*
126  * If the requested authorization is different from the current user,
127  * temporarily set the current user so that the object(s) will be created
128  * with the correct ownership.
129  *
130  * (The setting will be restored at the end of this routine, or in case of
131  * error, transaction abort will clean things up.)
132  */
133  if (saved_uid != owner_uid)
134  SetUserIdAndSecContext(owner_uid,
135  save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
136 
137  /* Create the schema's namespace */
138  namespaceId = NamespaceCreate(schemaName, owner_uid, false);
139 
140  /* Advance cmd counter to make the namespace visible */
142 
143  /*
144  * Temporarily make the new namespace be the front of the search path, as
145  * well as the default creation target namespace. This will be undone at
146  * the end of this routine, or upon error.
147  */
149  overridePath->schemas = lcons_oid(namespaceId, overridePath->schemas);
150  /* XXX should we clear overridePath->useTemp? */
151  PushOverrideSearchPath(overridePath);
152 
153  /*
154  * Report the new schema to possibly interested event triggers. Note we
155  * must do this here and not in ProcessUtilitySlow because otherwise the
156  * objects created below are reported before the schema, which would be
157  * wrong.
158  */
159  ObjectAddressSet(address, NamespaceRelationId, namespaceId);
161  (Node *) stmt);
162 
163  /*
164  * Examine the list of commands embedded in the CREATE SCHEMA command, and
165  * reorganize them into a sequentially executable order with no forward
166  * references. Note that the result is still a list of raw parsetrees ---
167  * we cannot, in general, run parse analysis on one statement until we
168  * have actually executed the prior ones.
169  */
170  parsetree_list = transformCreateSchemaStmt(stmt);
171 
172  /*
173  * Execute each command contained in the CREATE SCHEMA. Since the grammar
174  * allows only utility commands in CREATE SCHEMA, there is no need to pass
175  * them through parse_analyze() or the rewriter; we can just hand them
176  * straight to ProcessUtility.
177  */
178  foreach(parsetree_item, parsetree_list)
179  {
180  Node *stmt = (Node *) lfirst(parsetree_item);
181  PlannedStmt *wrapper;
182 
183  /* need to make a wrapper PlannedStmt */
184  wrapper = makeNode(PlannedStmt);
185  wrapper->commandType = CMD_UTILITY;
186  wrapper->canSetTag = false;
187  wrapper->utilityStmt = stmt;
188  wrapper->stmt_location = stmt_location;
189  wrapper->stmt_len = stmt_len;
190 
191  /* do this step */
192  ProcessUtility(wrapper,
193  queryString,
195  NULL,
196  NULL,
198  NULL);
199 
200  /* make sure later steps can see the object created here */
202  }
203 
204  /* Reset search path to normal state */
206 
207  /* Reset current user and security context */
208  SetUserIdAndSecContext(saved_uid, save_sec_context);
209 
210  return namespaceId;
211 }
212 
213 
214 /*
215  * Rename schema
216  */
218 RenameSchema(const char *oldname, const char *newname)
219 {
220  Oid nspOid;
221  HeapTuple tup;
222  Relation rel;
223  AclResult aclresult;
224  ObjectAddress address;
225  Form_pg_namespace nspform;
226 
227  rel = table_open(NamespaceRelationId, RowExclusiveLock);
228 
230  if (!HeapTupleIsValid(tup))
231  ereport(ERROR,
232  (errcode(ERRCODE_UNDEFINED_SCHEMA),
233  errmsg("schema \"%s\" does not exist", oldname)));
234 
235  nspform = (Form_pg_namespace) GETSTRUCT(tup);
236  nspOid = nspform->oid;
237 
238  /* make sure the new name doesn't exist */
239  if (OidIsValid(get_namespace_oid(newname, true)))
240  ereport(ERROR,
241  (errcode(ERRCODE_DUPLICATE_SCHEMA),
242  errmsg("schema \"%s\" already exists", newname)));
243 
244  /* must be owner */
245  if (!pg_namespace_ownercheck(nspOid, GetUserId()))
247  oldname);
248 
249  /* must have CREATE privilege on database */
251  if (aclresult != ACLCHECK_OK)
252  aclcheck_error(aclresult, OBJECT_DATABASE,
254 
255  if (!allowSystemTableMods && IsReservedName(newname))
256  ereport(ERROR,
257  (errcode(ERRCODE_RESERVED_NAME),
258  errmsg("unacceptable schema name \"%s\"", newname),
259  errdetail("The prefix \"pg_\" is reserved for system schemas.")));
260 
261  /* rename */
262  namestrcpy(&nspform->nspname, newname);
263  CatalogTupleUpdate(rel, &tup->t_self, tup);
264 
265  InvokeObjectPostAlterHook(NamespaceRelationId, nspOid, 0);
266 
267  ObjectAddressSet(address, NamespaceRelationId, nspOid);
268 
269  table_close(rel, NoLock);
270  heap_freetuple(tup);
271 
272  return address;
273 }
274 
275 void
276 AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
277 {
278  HeapTuple tup;
279  Relation rel;
280 
281  rel = table_open(NamespaceRelationId, RowExclusiveLock);
282 
284  if (!HeapTupleIsValid(tup))
285  elog(ERROR, "cache lookup failed for schema %u", oid);
286 
287  AlterSchemaOwner_internal(tup, rel, newOwnerId);
288 
289  ReleaseSysCache(tup);
290 
292 }
293 
294 
295 /*
296  * Change schema owner
297  */
299 AlterSchemaOwner(const char *name, Oid newOwnerId)
300 {
301  Oid nspOid;
302  HeapTuple tup;
303  Relation rel;
304  ObjectAddress address;
305  Form_pg_namespace nspform;
306 
307  rel = table_open(NamespaceRelationId, RowExclusiveLock);
308 
310  if (!HeapTupleIsValid(tup))
311  ereport(ERROR,
312  (errcode(ERRCODE_UNDEFINED_SCHEMA),
313  errmsg("schema \"%s\" does not exist", name)));
314 
315  nspform = (Form_pg_namespace) GETSTRUCT(tup);
316  nspOid = nspform->oid;
317 
318  AlterSchemaOwner_internal(tup, rel, newOwnerId);
319 
320  ObjectAddressSet(address, NamespaceRelationId, nspOid);
321 
322  ReleaseSysCache(tup);
323 
325 
326  return address;
327 }
328 
329 static void
331 {
332  Form_pg_namespace nspForm;
333 
334  Assert(tup->t_tableOid == NamespaceRelationId);
335  Assert(RelationGetRelid(rel) == NamespaceRelationId);
336 
337  nspForm = (Form_pg_namespace) GETSTRUCT(tup);
338 
339  /*
340  * If the new owner is the same as the existing owner, consider the
341  * command to have succeeded. This is for dump restoration purposes.
342  */
343  if (nspForm->nspowner != newOwnerId)
344  {
345  Datum repl_val[Natts_pg_namespace];
346  bool repl_null[Natts_pg_namespace];
347  bool repl_repl[Natts_pg_namespace];
348  Acl *newAcl;
349  Datum aclDatum;
350  bool isNull;
351  HeapTuple newtuple;
352  AclResult aclresult;
353 
354  /* Otherwise, must be owner of the existing object */
355  if (!pg_namespace_ownercheck(nspForm->oid, GetUserId()))
357  NameStr(nspForm->nspname));
358 
359  /* Must be able to become new owner */
360  check_is_member_of_role(GetUserId(), newOwnerId);
361 
362  /*
363  * must have create-schema rights
364  *
365  * NOTE: This is different from other alter-owner checks in that the
366  * current user is checked for create privileges instead of the
367  * destination owner. This is consistent with the CREATE case for
368  * schemas. Because superusers will always have this right, we need
369  * no special case for them.
370  */
372  ACL_CREATE);
373  if (aclresult != ACLCHECK_OK)
374  aclcheck_error(aclresult, OBJECT_DATABASE,
376 
377  memset(repl_null, false, sizeof(repl_null));
378  memset(repl_repl, false, sizeof(repl_repl));
379 
380  repl_repl[Anum_pg_namespace_nspowner - 1] = true;
381  repl_val[Anum_pg_namespace_nspowner - 1] = ObjectIdGetDatum(newOwnerId);
382 
383  /*
384  * Determine the modified ACL for the new owner. This is only
385  * necessary when the ACL is non-null.
386  */
387  aclDatum = SysCacheGetAttr(NAMESPACENAME, tup,
388  Anum_pg_namespace_nspacl,
389  &isNull);
390  if (!isNull)
391  {
392  newAcl = aclnewowner(DatumGetAclP(aclDatum),
393  nspForm->nspowner, newOwnerId);
394  repl_repl[Anum_pg_namespace_nspacl - 1] = true;
395  repl_val[Anum_pg_namespace_nspacl - 1] = PointerGetDatum(newAcl);
396  }
397 
398  newtuple = heap_modify_tuple(tup, RelationGetDescr(rel), repl_val, repl_null, repl_repl);
399 
400  CatalogTupleUpdate(rel, &newtuple->t_self, newtuple);
401 
402  heap_freetuple(newtuple);
403 
404  /* Update owner dependency reference */
405  changeDependencyOnOwner(NamespaceRelationId, nspForm->oid,
406  newOwnerId);
407  }
408 
409  InvokeObjectPostAlterHook(NamespaceRelationId,
410  nspForm->oid, 0);
411 }
ObjectAddress RenameSchema(const char *oldname, const char *newname)
Definition: schemacmds.c:218
static void AlterSchemaOwner_internal(HeapTuple tup, Relation rel, Oid newOwnerId)
Definition: schemacmds.c:330
Oid get_namespace_oid(const char *nspname, bool missing_ok)
Definition: namespace.c:3042
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Definition: table.c:167
#define GETSTRUCT(TUP)
Definition: htup_details.h:655
FormData_pg_namespace * Form_pg_namespace
Definition: pg_namespace.h:52
void SetUserIdAndSecContext(Oid userid, int sec_context)
Definition: miscinit.c:588
#define RelationGetDescr(relation)
Definition: rel.h:482
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Definition: miscinit.c:476
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Definition: name.c:233
NameData rolname
Definition: pg_authid.h:34
#define DatumGetAclP(X)
Definition: acl.h:120
#define PointerGetDatum(X)
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void AlterSchemaOwner_oid(Oid oid, Oid newOwnerId)
Definition: schemacmds.c:276
char * pstrdup(const char *in)
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Definition: pg_authid.h:56
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Definition: syscache.h:183
RoleSpec * authrole
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Definition: parsenodes.h:84
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int errdetail(const char *fmt,...)
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Definition: plannodes.h:92
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Definition: schemacmds.c:50
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AclResult
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uintptr_t Datum
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Definition: syscache.c:1164
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Definition: syscache.c:1377
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Definition: globals.c:85
Oid get_rolespec_oid(const RoleSpec *role, bool missing_ok)
Definition: acl.c:5209
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Definition: miscadmin.h:298
bool allowSystemTableMods
Definition: globals.c:120
#define InvalidOid
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AclResult pg_database_aclcheck(Oid db_oid, Oid roleid, AclMode mode)
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ObjectAddress AlterSchemaOwner(const char *name, Oid newOwnerId)
Definition: schemacmds.c:299
#define Assert(condition)
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Definition: pg_list.h:190
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const char * name
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Definition: objectaddress.h:40
List * transformCreateSchemaStmt(CreateSchemaStmt *stmt)
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const ObjectAddress InvalidObjectAddress
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