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Restrict psql meta-commands in plain-text dumps.
A malicious server could inject psql meta-commands into plain-text dump output (i.e., scripts created with pg_dump --format=plain, pg_dumpall, or pg_restore --file) that are run at restore time on the machine running psql. To fix, introduce a new "restricted" mode in psql that blocks all meta-commands (except for \unrestrict to exit the mode), and teach pg_dump, pg_dumpall, and pg_restore to use this mode in plain-text dumps. While at it, encourage users to only restore dumps generated from trusted servers or to inspect it beforehand, since restoring causes the destination to execute arbitrary code of the source superusers' choice. However, the client running the dump and restore needn't trust the source or destination superusers. Reported-by: Martin Rakhmanov Reported-by: Matthieu Denais <litezeraw@gmail.com> Reported-by: RyotaK <ryotak.mail@gmail.com> Suggested-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Noah Misch <noah@leadboat.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Reviewed-by: Peter Eisentraut <peter@eisentraut.org> Security: CVE-2025-8714 Backpatch-through: 13
1 parent 9b92f11 commit 575f54d

22 files changed

+433
-13
lines changed

‎doc/src/sgml/ref/pg_dump.sgml

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@@ -92,6 +92,18 @@ PostgreSQL documentation
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light of the limitations listed below.
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</para>
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<warning>
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<para>
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Restoring a dump causes the destination to execute arbitrary code of the
98+
source superusers' choice. Partial dumps and partial restores do not limit
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that. If the source superusers are not trusted, the dumped SQL statements
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must be inspected before restoring. Non-plain-text dumps can be inspected
101+
by using <application>pg_restore</application>'s <option>--file</option>
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option. Note that the client running the dump and restore need not trust
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the source or destination superusers.
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</para>
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</warning>
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</refsect1>
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<refsect1 id="pg-dump-options">
@@ -1207,6 +1219,29 @@ PostgreSQL documentation
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--restrict-key=<replaceable class="parameter">restrict_key</replaceable></option></term>
1224+
<listitem>
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<para>
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Use the provided string as the <application>psql</application>
1227+
<command>\restrict</command> key in the dump output. This can only be
1228+
specified for plain-text dumps, i.e., when <option>--format</option> is
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set to <literal>plain</literal> or the <option>--format</option> option
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is omitted. If no restrict key is specified,
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<application>pg_dump</application> will generate a random one as
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needed. Keys may contain only alphanumeric characters.
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</para>
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<para>
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This option is primarily intended for testing purposes and other
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scenarios that require repeatable output (e.g., comparing dump files).
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It is not recommended for general use, as a malicious server with
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advance knowledge of the key may be able to inject arbitrary code that
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will be executed on the machine that runs
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<application>psql</application> with the dump output.
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</para>
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</listitem>
1243+
</varlistentry>
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<varlistentry>
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<term><option>--rows-per-insert=<replaceable class="parameter">nrows</replaceable></option></term>
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<listitem>

‎doc/src/sgml/ref/pg_dumpall.sgml

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@@ -66,6 +66,16 @@ PostgreSQL documentation
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linkend="libpq-pgpass"/> for more information.
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</para>
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<warning>
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<para>
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Restoring a dump causes the destination to execute arbitrary code of the
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source superusers' choice. Partial dumps and partial restores do not limit
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that. If the source superusers are not trusted, the dumped SQL statements
74+
must be inspected before restoring. Note that the client running the dump
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and restore need not trust the source or destination superusers.
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</para>
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</warning>
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</refsect1>
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<refsect1>
@@ -555,6 +565,26 @@ exclude database <replaceable class="parameter">PATTERN</replaceable>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--restrict-key=<replaceable class="parameter">restrict_key</replaceable></option></term>
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<listitem>
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<para>
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Use the provided string as the <application>psql</application>
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<command>\restrict</command> key in the dump output. If no restrict
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key is specified, <application>pg_dumpall</application> will generate a
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random one as needed. Keys may contain only alphanumeric characters.
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</para>
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<para>
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This option is primarily intended for testing purposes and other
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scenarios that require repeatable output (e.g., comparing dump files).
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It is not recommended for general use, as a malicious server with
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advance knowledge of the key may be able to inject arbitrary code that
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will be executed on the machine that runs
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<application>psql</application> with the dump output.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--rows-per-insert=<replaceable class="parameter">nrows</replaceable></option></term>
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<listitem>

‎doc/src/sgml/ref/pg_restore.sgml

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@@ -68,6 +68,18 @@ PostgreSQL documentation
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<application>pg_restore</application> will not be able to load the data
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using <command>COPY</command> statements.
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</para>
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<warning>
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<para>
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Restoring a dump causes the destination to execute arbitrary code of the
75+
source superusers' choice. Partial dumps and partial restores do not limit
76+
that. If the source superusers are not trusted, the dumped SQL statements
77+
must be inspected before restoring. Non-plain-text dumps can be inspected
78+
by using <application>pg_restore</application>'s <option>--file</option>
79+
option. Note that the client running the dump and restore need not trust
80+
the source or destination superusers.
81+
</para>
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</warning>
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</refsect1>
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<refsect1 id="app-pgrestore-options">
@@ -755,6 +767,28 @@ PostgreSQL documentation
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--restrict-key=<replaceable class="parameter">restrict_key</replaceable></option></term>
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<listitem>
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<para>
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Use the provided string as the <application>psql</application>
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<command>\restrict</command> key in the dump output. This can only be
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specified for SQL script output, i.e., when the <option>--file</option>
777+
option is used. If no restrict key is specified,
778+
<application>pg_restore</application> will generate a random one as
779+
needed. Keys may contain only alphanumeric characters.
780+
</para>
781+
<para>
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This option is primarily intended for testing purposes and other
783+
scenarios that require repeatable output (e.g., comparing dump files).
784+
It is not recommended for general use, as a malicious server with
785+
advance knowledge of the key may be able to inject arbitrary code that
786+
will be executed on the machine that runs
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<application>psql</application> with the dump output.
788+
</para>
789+
</listitem>
790+
</varlistentry>
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758792
<varlistentry>
759793
<term><option>--section=<replaceable class="parameter">sectionname</replaceable></option></term>
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<listitem>

‎doc/src/sgml/ref/pgupgrade.sgml

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@@ -70,6 +70,14 @@ PostgreSQL documentation
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pg_upgrade supports upgrades from 9.2.X and later to the current
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major release of <productname>PostgreSQL</productname>, including snapshot and beta releases.
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</para>
73+
74+
<warning>
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<para>
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Upgrading a cluster causes the destination to execute arbitrary code of the
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source superusers' choice. Ensure that the source superusers are trusted
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before upgrading.
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</para>
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</warning>
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</refsect1>
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<refsect1>

‎doc/src/sgml/ref/psql-ref.sgml

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@@ -3340,6 +3340,24 @@ lo_import 152801
33403340
</varlistentry>
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<varlistentry id="app-psql-meta-command-restrict">
3344+
<term><literal>\restrict <replaceable class="parameter">restrict_key</replaceable></literal></term>
3345+
<listitem>
3346+
<para>
3347+
Enter "restricted" mode with the provided key. In this mode, the only
3348+
allowed meta-command is <command>\unrestrict</command>, to exit
3349+
restricted mode. The key may contain only alphanumeric characters.
3350+
</para>
3351+
<para>
3352+
This command is primarily intended for use in plain-text dumps
3353+
generated by <application>pg_dump</application>,
3354+
<application>pg_dumpall</application>, and
3355+
<application>pg_restore</application>, but it may be useful elsewhere.
3356+
</para>
3357+
</listitem>
3358+
</varlistentry>
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3360+
33433361
<varlistentry id="app-psql-meta-command-s">
33443362
<term><literal>\s [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
33453363
<listitem>
@@ -3514,6 +3532,24 @@ testdb=&gt; <userinput>\setenv LESS -imx4F</userinput>
35143532
</varlistentry>
35153533

35163534

3535+
<varlistentry id="app-psql-meta-command-unrestrict">
3536+
<term><literal>\unrestrict <replaceable class="parameter">restrict_key</replaceable></literal></term>
3537+
<listitem>
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<para>
3539+
Exit "restricted" mode (i.e., where all other meta-commands are
3540+
blocked), provided the specified key matches the one given to
3541+
<command>\restrict</command> when restricted mode was entered.
3542+
</para>
3543+
<para>
3544+
This command is primarily intended for use in plain-text dumps
3545+
generated by <application>pg_dump</application>,
3546+
<application>pg_dumpall</application>, and
3547+
<application>pg_restore</application>, but it may be useful elsewhere.
3548+
</para>
3549+
</listitem>
3550+
</varlistentry>
3551+
3552+
35173553
<varlistentry id="app-psql-meta-command-unset">
35183554
<term><literal>\unset <replaceable class="parameter">name</replaceable></literal></term>
35193555

‎src/bin/pg_combinebackup/t/002_compare_backups.pl

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@@ -171,6 +171,7 @@
171171
[
172172
'pg_dumpall', '-f',
173173
$dump1, '--no-sync',
174+
'--restrict-key=test',
174175
'--no-unlogged-table-data', '-d',
175176
$pitr1->connstr('postgres'),
176177
],
@@ -179,6 +180,7 @@
179180
[
180181
'pg_dumpall', '-f',
181182
$dump2, '--no-sync',
183+
'--restrict-key=test',
182184
'--no-unlogged-table-data', '-d',
183185
$pitr2->connstr('postgres'),
184186
],

‎src/bin/pg_dump/dumputils.c

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@@ -19,6 +19,7 @@
1919
#include "dumputils.h"
2020
#include "fe_utils/string_utils.h"
2121

22+
static const char restrict_chars[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
2223

2324
static bool parseAclItem(const char *item, const char *type,
2425
const char *name, const char *subname, int remoteVersion,
@@ -920,3 +921,40 @@ makeAlterConfigCommand(PGconn *conn, const char *configitem,
920921

921922
pg_free(mine);
922923
}
924+
925+
/*
926+
* Generates a valid restrict key (i.e., an alphanumeric string) for use with
927+
* psql's \restrict and \unrestrict meta-commands. For safety, the value is
928+
* chosen at random.
929+
*/
930+
char *
931+
generate_restrict_key(void)
932+
{
933+
uint8 buf[64];
934+
char *ret = palloc(sizeof(buf));
935+
936+
if (!pg_strong_random(buf, sizeof(buf)))
937+
return NULL;
938+
939+
for (int i = 0; i < sizeof(buf) - 1; i++)
940+
{
941+
uint8 idx = buf[i] % strlen(restrict_chars);
942+
943+
ret[i] = restrict_chars[idx];
944+
}
945+
ret[sizeof(buf) - 1] = '\0';
946+
947+
return ret;
948+
}
949+
950+
/*
951+
* Checks that a given restrict key (intended for use with psql's \restrict and
952+
* \unrestrict meta-commands) contains only alphanumeric characters.
953+
*/
954+
bool
955+
valid_restrict_key(const char *restrict_key)
956+
{
957+
return restrict_key != NULL &&
958+
restrict_key[0] != '\0' &&
959+
strspn(restrict_key, restrict_chars) == strlen(restrict_key);
960+
}

‎src/bin/pg_dump/dumputils.h

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@@ -64,4 +64,7 @@ extern void makeAlterConfigCommand(PGconn *conn, const char *configitem,
6464
const char *type2, const char *name2,
6565
PQExpBuffer buf);
6666

67+
extern char *generate_restrict_key(void);
68+
extern bool valid_restrict_key(const char *restrict_key);
69+
6770
#endif /* DUMPUTILS_H */

‎src/bin/pg_dump/pg_backup.h

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@@ -157,6 +157,8 @@ typedef struct _restoreOptions
157157
int enable_row_security;
158158
int sequence_data; /* dump sequence data even in schema-only mode */
159159
int binary_upgrade;
160+
161+
char *restrict_key;
160162
} RestoreOptions;
161163

162164
typedef struct _dumpOptions
@@ -203,6 +205,8 @@ typedef struct _dumpOptions
203205

204206
int sequence_data; /* dump sequence data even in schema-only mode */
205207
int do_nothing;
208+
209+
char *restrict_key;
206210
} DumpOptions;
207211

208212
/*

‎src/bin/pg_dump/pg_backup_archiver.c

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Original file line numberDiff line numberDiff line change
@@ -187,6 +187,7 @@ dumpOptionsFromRestoreOptions(RestoreOptions *ropt)
187187
dopt->include_everything = ropt->include_everything;
188188
dopt->enable_row_security = ropt->enable_row_security;
189189
dopt->sequence_data = ropt->sequence_data;
190+
dopt->restrict_key = ropt->restrict_key ? pg_strdup(ropt->restrict_key) : NULL;
190191

191192
return dopt;
192193
}
@@ -451,6 +452,17 @@ RestoreArchive(Archive *AHX)
451452

452453
ahprintf(AH, "--\n-- PostgreSQL database dump\n--\n\n");
453454

455+
/*
456+
* If generating plain-text output, enter restricted mode to block any
457+
* unexpected psql meta-commands. A malicious source might try to inject
458+
* a variety of things via bogus responses to queries. While we cannot
459+
* prevent such sources from affecting the destination at restore time, we
460+
* can block psql meta-commands so that the client machine that runs psql
461+
* with the dump output remains unaffected.
462+
*/
463+
if (ropt->restrict_key)
464+
ahprintf(AH, "\\restrict %s\n\n", ropt->restrict_key);
465+
454466
if (AH->archiveRemoteVersion)
455467
ahprintf(AH, "-- Dumped from database version %s\n",
456468
AH->archiveRemoteVersion);
@@ -791,6 +803,14 @@ RestoreArchive(Archive *AHX)
791803

792804
ahprintf(AH, "--\n-- PostgreSQL database dump complete\n--\n\n");
793805

806+
/*
807+
* If generating plain-text output, exit restricted mode at the very end
808+
* of the script. This is not pro forma; in particular, pg_dumpall
809+
* requires this when transitioning from one database to another.
810+
*/
811+
if (ropt->restrict_key)
812+
ahprintf(AH, "\\unrestrict %s\n\n", ropt->restrict_key);
813+
794814
/*
795815
* Clean up & we're done.
796816
*/
@@ -3349,11 +3369,21 @@ _reconnectToDB(ArchiveHandle *AH, const char *dbname)
33493369
else
33503370
{
33513371
PQExpBufferData connectbuf;
3372+
RestoreOptions *ropt = AH->public.ropt;
3373+
3374+
/*
3375+
* We must temporarily exit restricted mode for \connect, etc.
3376+
* Anything added between this line and the following \restrict must
3377+
* be careful to avoid any possible meta-command injection vectors.
3378+
*/
3379+
ahprintf(AH, "\\unrestrict %s\n", ropt->restrict_key);
33523380

33533381
initPQExpBuffer(&connectbuf);
33543382
appendPsqlMetaConnect(&connectbuf, dbname);
3355-
ahprintf(AH, "%s\n", connectbuf.data);
3383+
ahprintf(AH, "%s", connectbuf.data);
33563384
termPQExpBuffer(&connectbuf);
3385+
3386+
ahprintf(AH, "\\restrict %s\n\n", ropt->restrict_key);
33573387
}
33583388

33593389
/*

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