8000 Empty search_path in Autovacuum and non-psql/pgbench clients. · yazun/postgres@91f3ffc · GitHub
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Empty search_path in Autovacuum and non-psql/pgbench clients.
This makes the client programs behave as documented regardless of the connect-time search_path and regardless of user-created objects. Today, a malicious user with CREATE permission on a search_path schema can take control of certain of these clients' queries and invoke arbitrary SQL functions under the client identity, often a superuser. This is exploitable in the default configuration, where all users have CREATE privilege on schema "public". This changes behavior of user-defined code stored in the database, like pg_index.indexprs and pg_extension_config_dump(). If they reach code bearing unqualified names, "does not exist" or "no schema has been selected to create in" errors might appear. Users may fix such errors by schema-qualifying affected names. After upgrading, consider watching server logs for these errors. The --table arguments of src/bin/scripts clients have been lax; for example, "vacuumdb -Zt pg_am\;CHECKPOINT" performed a checkpoint. That now fails, but for now, "vacuumdb -Zt 'pg_am(amname);CHECKPOINT'" still performs a checkpoint. Back-patch to 9.3 (all supported versions). Reviewed by Tom Lane, though this fix strategy was not his first choice. Reported by Arseniy Sharoglazov. Security: CVE-2018-1058
1 parent a8fc37a commit 91f3ffc

28 files changed

+360
-89
lines changed

‎contrib/oid2name/oid2name.c

Lines changed: 13 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@
99
*/
1010
#include "postgres_fe.h"
1111

12+
#include "fe_utils/connect.h"
1213
#include "libpq-fe.h"
1314
#include "pg_getopt.h"
1415

@@ -263,6 +264,7 @@ sql_conn(struct options * my_opts)
263264
PGconn *conn;
264265
char *password = NULL;
265266
bool new_pass;
267+
PGresult *res;
266268

267269
/*
268270
* Start the connection. Loop until we have a password if requested by
@@ -322,6 +324,17 @@ sql_conn(struct options * my_opts)
322324
exit(1);
323325
}
324326

327+
res = PQexec(conn, ALWAYS_SECURE_SEARCH_PATH_SQL);
328+
if (PQresultStatus(res) != PGRES_TUPLES_OK)
329+
{
330+
fprintf(stderr, "oid2name: could not clear search_path: %s\n",
331+
PQerrorMessage(conn));
332+
PQclear(res);
333+
PQfinish(conn);
334+
exit(-1);
335+
}
336+
PQclear(res);
337+
325338
/* return the conn if good */
326339
return conn;
327340
}

‎contrib/vacuumlo/vacuumlo.c

Lines changed: 3 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -21,6 +21,7 @@
2121
#include <termios.h>
2222
#endif
2323

24+
#include "fe_utils/connect.h"
2425
#include "libpq-fe.h"
2526
#include "pg_getopt.h"
2627

@@ -135,11 +136,8 @@ vacuumlo(const char *database, const struct _param * param)
135136
fprintf(stdout, "Test run: no large objects will be removed!\n");
136137
}
137138

138-
/*
139-
* Don't get fooled by any non-system catalogs
140-
*/
141-
res = PQexec(conn, "SET search_path = pg_catalog");
142-
if (PQresultStatus(res) != PGRES_COMMAND_OK)
139+
res = PQexec(conn, ALWAYS_SECURE_SEARCH_PATH_SQL);
140+
if (PQresultStatus(res) != PGRES_TUPLES_OK)
143141
{
144142
fprintf(stderr, "Failed to set search_path:\n");
145143
fprintf(stderr, "%s", PQerrorMessage(conn));

‎src/backend/postmaster/autovacuum.c

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -530,6 +530,12 @@ AutoVacLauncherMain(int argc, char *argv[])
530530
/* must unblock signals before calling rebuild_database_list */
531531
PG_SETMASK(&UnBlockSig);
532532

533+
/*
534+
* Set always-secure search path. Launcher doesn't connect to a database,
535+
* so this has no effect.
536+
*/
537+
SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
538+
533539
/*
534540
* Force zero_damaged_pages OFF in the autovac process, even if it is set
535541
* in postgresql.conf. We don't really want such a dangerous option being
@@ -1543,6 +1549,14 @@ AutoVacWorkerMain(int argc, char *argv[])
15431549

15441550
PG_SETMASK(&UnBlockSig);
15451551

1552+
/*
1553+
* Set always-secure search path, so malicious users can't redirect user
1554+
* code (e.g. pg_index.indexprs). (That code runs in a
1555+
* SECURITY_RESTRICTED_OPERATION sandbox, so malicious users could not
1556+
* take control of the entire autovacuum worker in any case.)
1557+
*/
1558+
SetConfigOption("search_path", "", PGC_SUSET, PGC_S_OVERRIDE);
1559+
15461560
/*
15471561
* Force zero_damaged_pages OFF in the autovac process, even if it is set
15481562
* in postgresql.conf. We don't really want such a dangerous option being

‎src/bin/pg_basebackup/streamutil.c

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,7 @@
3030
#include "pqexpbuffer.h"
3131
#include "common/fe_memutils.h"
3232
#include "datatype/timestamp.h"
33+
#include "fe_utils/connect.h"
3334

3435
#define ERRCODE_DUPLICATE_OBJECT "42710"
3536

@@ -208,6 +209,23 @@ GetConnection(void)
208209
if (conn_opts)
209210
PQconninfoFree(conn_opts);
210211

212+
/* Set always-secure search path, so malicious users can't get control. */
213+
if (dbname != NULL)
214+
{
215+
PGresult *res;
216+
217+
res = PQexec(tmpconn, ALWAYS_SECURE_SEARCH_PATH_SQL);
218+
if (PQresultStatus(res) != PGRES_TUPLES_OK)
219+
{
220+
fprintf(stderr, _("%s: could not clear search_path: %s\n"),
221+
progname, PQerrorMessage(tmpconn));
222+
PQclear(res);
223+
PQfinish(tmpconn);
224+
exit(1);
225+
}
226+
PQclear(res);
227+
}
228+
211229
/*
212230
* Ensure we have the same value of integer timestamps as the server we
213231
* are connecting to.

‎src/bin/pg_dump/dumputils.c

Lines changed: 10 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1376,8 +1376,9 @@ processSQLNamePattern(PGconn *conn, PQExpBuffer buf, const char *pattern,
13761376
}
13771377

13781378
/*
1379-
* Now decide what we need to emit. Note there will be a leading "^(" in
1380-
* the patterns in any case.
1379+
* Now decide what we need to emit. We may run under a hostile
1380+
* search_path, so qualify EVERY name. Note there will be a leading "^("
1381+
* in the patterns in any case.
13811382
*/
13821383
if (namebuf.len > 2)
13831384
{
@@ -1390,15 +1391,18 @@ processSQLNamePattern(PGconn *conn, PQExpBuffer buf, const char *pattern,
13901391
WHEREAND();
13911392
if (altnamevar)
13921393
{
1393-
appendPQExpBuffer(buf, "(%s ~ ", namevar);
1394+
appendPQExpBuffer(buf,
1395+
"(%s OPERATOR(pg_catalog.~) ", namevar);
13941396
appendStringLiteralConn(buf, namebuf.data, conn);
1395-
appendPQExpBuffer(buf, "\n OR %s ~ ", altnamevar);
1397+
appendPQExpBuffer(buf,
1398+
"\n OR %s OPERATOR(pg_catalog.~) ",
1399+
altnamevar);
13961400
appendStringLiteralConn(buf, namebuf.data, conn);
13971401
appendPQExpBufferStr(buf, ")\n");
13981402
}
13991403
else
14001404
{
1401-
appendPQExpBuffer(buf, "%s ~ ", namevar);
1405+
appendPQExpBuffer(buf, "%s OPERATOR(pg_catalog.~) ", namevar);
14021406
appendStringLiteralConn(buf, namebuf.data, conn);
14031407
appendPQExpBufferChar(buf, '\n');
14041408
}
@@ -1414,7 +1418,7 @@ processSQLNamePattern(PGconn *conn, PQExpBuffer buf, const char *pattern,
14141418
if (strcmp(schemabuf.data, "^(.*)$") != 0 && schemavar)
14151419
{
14161420
WHEREAND();
1417-
appendPQExpBuffer(buf, "%s ~ ", schemavar);
1421+
appendPQExpBuffer(buf, "%s OPERATOR(pg_catalog.~) ", schemavar);
14181422
appendStringLiteralConn(buf, schemabuf.data, conn);
14191423
appendPQExpBufferChar(buf, '\n');
14201424
}

‎src/bin/pg_dump/pg_backup_db.c

Lines changed: 11 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
1212
#include "postgres_fe.h"
1313

1414
#include "dumputils.h"
15+
#include "fe_utils/connect.h"
1516
#include "parallel.h"
1617
#include "pg_backup_archiver.h"
1718
#include "pg_backup_db.h"
@@ -113,6 +114,11 @@ ReconnectToServer(ArchiveHandle *AH, const char *dbname, const char *username)
113114
PQfinish(AH->connection);
114115
AH->connection = newConn;
115116

117+
/* Start strict; later phases may override this. */
118+
if (PQserverVersion(AH->connection) >= 70300)
119+
PQclear(ExecuteSqlQueryForSingleRow((Archive *) AH,
120+
ALWAYS_SECURE_SEARCH_PATH_SQL));
121+
116122
return 1;
117123
}
118124

@@ -321,6 +327,11 @@ ConnectDatabase(Archive *AHX,
321327
PQdb(AH->connection) ? PQdb(AH->connection) : "",
322328
PQerrorMessage(AH->connection));
323329

330+
/* Start strict; later phases may override this. */
331+
if (PQserverVersion(AH->connection) >= 70300)
332+
PQclear(ExecuteSqlQueryForSingleRow((Archive *) AH,
333+
ALWAYS_SECURE_SEARCH_PATH_SQL));
334+
324335
/*
325336
* We want to remember connection's actual password, whether or not we got
326337
* it by prompting. So we don't just store the password variable.

‎src/bin/pg_dump/pg_dump.c

Lines changed: 15 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -60,6 +60,7 @@
6060
#include "pg_backup_db.h"
6161
#include "pg_backup_utils.h"
6262
#include "pg_dump.h"
63+
#include "fe_utils/connect.h"
6364

6465

6566
typedef struct
@@ -965,6 +966,9 @@ setup_connection(Archive *AH, const char *dumpencoding,
965966
PGconn *conn = GetConnection(AH);
966967
const char *std_strings;
967968

969+
if (AH->remoteVersion >= 70300)
970+
PQclear(ExecuteSqlQueryForSingleRow(AH, ALWAYS_SECURE_SEARCH_PATH_SQL));
971+
968972
/*
969973
* Set the client encoding if requested.
970974
*/
@@ -1257,21 +1261,30 @@ expand_table_name_patterns(Archive *fout,
12571261

12581262
for (cell = patterns->head; cell; cell = cell->next)
12591263
{
1264+
/*
1265+
* Query must remain ABSOLUTELY devoid of unqualified names. This
1266+
* would be unnecessary given a pg_table_is_visible() variant taking a
1267+
* search_path argument.
1268+
*/
12601269
if (cell != patterns->head)
12611270
appendPQExpBufferStr(query, "UNION ALL\n");
12621271
appendPQExpBuffer(query,
12631272
"SELECT c.oid"
12641273
"\nFROM pg_catalog.pg_class c"
1265-
"\n LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace"
1266-
"\nWHERE c.relkind in ('%c', '%c', '%c', '%c', '%c')\n",
1274+
"\n LEFT JOIN pg_catalog.pg_namespace n"
1275+
"\n ON n.oid OPERATOR(pg_catalog.=) c.relnamespace"
1276+
"\nWHERE c.relkind OPERATOR(pg_catalog.=) ANY"
1277+
"\n (array['%c', '%c', '%c', '%c', '%c'])\n",
12671278
RELKIND_RELATION, RELKIND_SEQUENCE, RELKIND_VIEW,
12681279
RELKIND_MATVIEW, RELKIND_FOREIGN_TABLE);
12691280
processSQLNamePattern(GetConnection(fout), query, cell->val, true,
12701281
false, "n.nspname", "c.relname", NULL,
12711282
"pg_catalog.pg_table_is_visible(c.oid)");
12721283
}
12731284

1285+
ExecuteSqlStatement(fout, "RESET search_path");
12741286
res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK);
1287+
PQclear(ExecuteSqlQueryForSingleRow(fout, ALWAYS_SECURE_SEARCH_PATH_SQL));
12751288

12761289
for (i = 0; i < PQntuples(res); i++)
12771290
{

‎src/bin/pg_dump/pg_dumpall.c

Lines changed: 2 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -26,6 +26,7 @@
2626

2727
#include "dumputils.h"
2828
#include "pg_backup.h"
29+
#include "fe_utils/connect.h"
2930

3031
/* version string we expect back from pg_dump */
3132
#define PGDUMP_VERSIONSTR "pg_dump (PostgreSQL) " PG_VERSION "\n"
@@ -1983,12 +1984,8 @@ connectDatabase(const char *dbname, const char *connection_string,
19831984
exit_nicely(1);
19841985
}
19851986

1986-
/*
1987-
* On 7.3 and later, make sure we are not fooled by non-system schemas in
1988-
* the search path.
1989-
*/
19901987
if (server_version >= 70300)
1991-
executeCommand(conn, "SET search_path = pg_catalog");
1988+
PQclear(executeQuery(conn, ALWAYS_SECURE_SEARCH_PATH_SQL));
19921989

19931990
return conn;
19941991
}

‎src/bin/pg_rewind/libpq 10000 _fetch.c

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -29,6 +29,7 @@
2929
#include "libpq-fe.h"
3030
#include "catalog/catalog.h"
3131
#include "catalog/pg_type.h"
32+
#include "fe_utils/connect.h"
3233

3334
static PGconn *conn = NULL;
3435

@@ -58,6 +59,12 @@ libpqConnect(const char *connstr)
5859

5960
pg_log(PG_PROGRESS, "connected to server\n");
6061

62+
res = PQexec(conn, ALWAYS_SECURE_SEARCH_PATH_SQL);
63+
if (PQresultStatus(res) != PGRES_TUPLES_OK)
64+
pg_fatal("could not clear search_path: %s",
65+
PQresultErrorMessage(res));
66+
PQclear(res);
67+
6168
/*
6269
* Check that the server is not in hot standby mode. There is no
6370
* fundamental reason that couldn't be made to work, but it doesn't

‎src/bin/pg_upgrade/server.c

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -9,6 +9,7 @@
99

1010
#include "postgres_fe.h"
1111

12+
#include "fe_utils/connect.h"
1213
#include "pg_upgrade.h"
1314

1415

@@ -39,6 +40,8 @@ connectToServer(ClusterInfo *cluster, const char *db_name)
3940
exit(1);
4041
}
4142

43+
PQclear(executeQueryOrDie(conn, ALWAYS_SECURE_SEARCH_PATH_SQL));
44+
4245
return conn;
4346
}
4447

‎src/bin/scripts/Makefile

Lines changed: 12 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -25,16 +25,17 @@ all: $(PROGRAMS)
2525
%: %.o $(WIN32RES)
2626
$(CC) $(CFLAGS) $^ $(libpq_pgport) $(LDFLAGS) $(LDFLAGS_EX) $(LIBS) -o $@$(X)
2727

28-
createdb: createdb.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
29-
createlang: createlang.o common.o print.o mbprint.o | submake-libpq submake-libpgport
30-
createuser: createuser.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
31-
dropdb: dropdb.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
32-
droplang: droplang.o common.o print.o mbprint.o | submake-libpq submake-libpgport
33-
dropuser: dropuser.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
34-
clusterdb: clusterdb.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
35-
vacuumdb: vacuumdb.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
36-
reindexdb: reindexdb.o common.o dumputils.o kwlookup.o keywords.o | submake-libpq submake-libpgport
37-
pg_isready: pg_isready.o common.o | submake-libpq submake-libpgport
28+
SCRIPTS_COMMON = common.o dumputils.o kwlookup.o keywords.o
29+
createdb: createdb.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
30+
createlang: createlang.o $(SCRIPTS_COMMON) print.o mbprint.o | submake-libpq submake-libpgport
31+
createuser: createuser.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
32+
dropdb: dropdb.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
33+
droplang: droplang.o $(SCRIPTS_COMMON) print.o mbprint.o | submake-libpq submake-libpgport
34+
dropuser: dropuser.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
35+
clusterdb: clusterdb.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
36+
vacuumdb: vacuumdb.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
37+
reindexdb: reindexdb.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
38+
pg_isready: pg_isready.o $(SCRIPTS_COMMON) | submake-libpq submake-libpgport
3839

3940
dumputils.c keywords.c: % : $(top_srcdir)/src/bin/pg_dump/%
4041
rm -f $@ && $(LN_S) $< .
@@ -65,7 +66,7 @@ uninstall:
6566

6667
clean distclean maintainer-clean:
6768
rm -f $(addsuffix $(X), $(PROGRAMS)) $(addsuffix .o, $(PROGRAMS))
68-
rm -f common.o dumputils.o kwlookup.o keywords.o print.o mbprint.o $(WIN32RES)
69+
rm -f $(SCRIPTS_COMMON) print.o mbprint.o $(WIN32RES)
6970
rm -f dumputils.c print.c mbprint.c kwlookup.c keywords.c
7071
rm -rf tmp_check
7172

‎src/bin/scripts/clusterdb.c

Lines changed: 8 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -194,17 +194,21 @@ cluster_one_database(const char *dbname, bool verbose, const char *table,
194194

195195
PGconn *conn;
196196

197+
conn = connectDatabase(dbname, host, port, username, prompt_password,
198+
progname, echo, false, false);
199+
197200
initPQExpBuffer(&sql);
198201

199202
appendPQExpBufferStr(&sql, "CLUSTER");
200203
if (verbose)
201204
appendPQExpBufferStr(&sql, " VERBOSE");
202205
if (table)
203-
appendPQExpBuffer(&sql, " %s", table);
206+
{
207+
appendPQExpBufferChar(&sql, ' ');
208+
appendQualifiedRelation(&sql, table, conn, progname, echo);
209+
}
204210
appendPQExpBufferChar(&sql, ';');
205211

206-
conn = connectDatabase(dbname, host, port, username, prompt_password,
207-
progname, false, false);
208212
if (!executeMaintenanceCommand(conn, sql.data, echo))
209213
{
210214
if (table)
@@ -233,7 +237,7 @@ cluster_all_databases(bool verbose, const char *maintenance_db,
233237
int i;
234238

235239
conn = connectMaintenanceDatabase(maintenance_db, host, port, username,
236-
prompt_password, progname);
240+
prompt_password, progname, echo);
237241
result = executeQuery(conn, "SELECT datname FROM pg_database WHERE datallowconn ORDER BY 1;", progname, echo);
238242
PQfinish(conn);
239243

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