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Commitf1325ce

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Add large object access control.
A new system catalog pg_largeobject_metadata managesownership and access privileges of large objects.KaiGai Kohei, reviewed by Jaime Casanova.
1 parent6457996 commitf1325ce

39 files changed

+1439
-162
lines changed

‎doc/src/sgml/catalogs.sgml

Lines changed: 71 additions & 5 deletions
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@@ -1,4 +1,4 @@
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<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.212 2009/12/07 05:22:21 tgl Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/catalogs.sgml,v 2.213 2009/12/11 03:34:54 itagaki Exp $ -->
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<!--
33
Documentation of the system catalogs, directed toward PostgreSQL developers
44
-->
@@ -160,7 +160,12 @@
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161161
<row>
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<entry><link linkend="catalog-pg-largeobject"><structname>pg_largeobject</structname></link></entry>
163-
<entry>large objects</entry>
163+
<entry>data pages for large objects</entry>
164+
</row>
165+
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<row>
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<entry><link linkend="catalog-pg-largeobject-metadata"><structname>pg_largeobject_metadata</structname></link></entry>
168+
<entry>metadata for large objects</entry>
164169
</row>
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166171
<row>
@@ -3120,22 +3125,31 @@
31203125

31213126
<para>
31223127
The catalog <structname>pg_largeobject</structname> holds the data making up
3123-
<quote>large objects</quote>. A large object is identified by an
3124-
OID assigned when it is created. Each large object is broken into
3128+
<quote>large objects</quote>. A large object is identified by an OID of
3129+
<link linkend="catalog-pg-largeobject-metadata"><structname>pg_largeobject_metadata</></link>
3130+
catalog, assigned when it is created. Each large object is broken into
31253131
segments or <quote>pages</> small enough to be conveniently stored as rows
31263132
in <structname>pg_largeobject</structname>.
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The amount of data per page is defined to be <symbol>LOBLKSIZE</> (which is currently
31283134
<literal>BLCKSZ/4</>, or typically 2 kB).
31293135
</para>
31303136

3137+
<para>
3138+
<structname>pg_largeobject</structname> should not be readable by the
3139+
public, since the catalog contains data in large objects of all users.
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<structname>pg_largeobject_metadata</> is a publicly readable catalog
3141+
that only contains identifiers of large objects.
3142+
</para>
3143+
31313144
<table>
31323145
<title><structname>pg_largeobject</> Columns</title>
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3134-
<tgroup cols="3">
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<tgroup cols="4">
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<thead>
31363149
<row>
31373150
<entry>Name</entry>
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<entry>Type</entry>
3152+
<entry>References</entry>
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<entry>Description</entry>
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</row>
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</thead>
@@ -3144,19 +3158,22 @@
31443158
<row>
31453159
<entry><structfield>loid</structfield></entry>
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<entry><type>oid</type></entry>
3161+
<entry><literal><link linkend="catalog-pg-largeobject-metadata"><structname>pg_largeobject_metadata</structname></link>.oid</literal></entry>
31473162
<entry>Identifier of the large object that includes this page</entry>
31483163
</row>
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31503165
<row>
31513166
<entry><structfield>pageno</structfield></entry>
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<entry><type>int4</type></entry>
3168+
<entry></entry>
31533169
<entry>Page number of this page within its large object
31543170
(counting from zero)</entry>
31553171
</row>
31563172

31573173
<row>
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<entry><structfield>data</structfield></entry>
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<entry><type>bytea</type></entry>
3176+
<entry></entry>
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<entry>
31613178
Actual data stored in the large object.
31623179
This will never be more than <symbol>LOBLKSIZE</> bytes and might be less
@@ -3177,6 +3194,55 @@
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31783195
</sect1>
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3197+
<sect1 id="catalog-pg-largeobject-metadata">
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<title><structname>pg_largeobject_metadata</structname></title>
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3200+
<indexterm zone="catalog-pg-largeobject-metadata">
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<primary>pg_largeobject_metadata</primary>
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</indexterm>
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<para>
3205+
The purpose of <structname>pg_largeobject_metadata</structname> is to
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hold metadata of <quote>large objects</quote>, such as OID of its owner,
3207+
access permissions and OID of the large object itself.
3208+
</para>
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3210+
<table>
3211+
<title><structname>pg_largeobject_metadata</> Columns</title>
3212+
3213+
<tgroup cols="4">
3214+
<thead>
3215+
<row>
3216+
<entry>Name</entry>
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<entry>Type</entry>
3218+
<entry>References</entry>
3219+
<entry>Description</entry>
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</row>
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</thead>
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3223+
<tbody>
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<row>
3225+
<entry><structfield>lomowner</structfield></entry>
3226+
<entry><type>oid</type></entry>
3227+
<entry><literal><link linkend="catalog-pg-authid"><structname>pg_authid</structname></link>.oid</literal></entry>
3228+
<entry>Owner of the largeobejct</entry>
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</row>
3230+
3231+
<row>
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<entry><structfield>lomacl</structfield></entry>
3233+
<entry><type>aclitem[]</type></entry>
3234+
<entry>
3235+
Access privileges; see
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<xref linkend="sql-grant" endterm="sql-grant-title"> and
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<xref linkend="sql-revoke" endterm="sql-revoke-title">
3238+
for details
3239+
</entry>
3240+
</row>
3241+
3242+
</tbody>
3243+
</tgroup>
3244+
</table>
3245+
</sect1>
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<sect1 id="catalog-pg-listener">
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<title><structname>pg_listener</structname></title>

‎doc/src/sgml/config.sgml

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@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.236 2009/12/10 06:32:27 petere Exp $ -->
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<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.237 2009/12/11 03:34:55 itagaki Exp $ -->
22

33
<chapter Id="runtime-config">
44
<title>Server Configuration</title>
@@ -4816,6 +4816,35 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
48164816
</listitem>
48174817
</varlistentry>
48184818

4819+
<varlistentry id="guc-lo-compat-privileges" xreflabel="lo_compat_privileges">
4820+
<term><varname>lo_compat_privileges</varname> (<type>boolean</type>)</term>
4821+
<indexterm>
4822+
<primary>
4823+
<varname>lo_compat_privileges</varname> configuration parameter
4824+
</primary>
4825+
</indexterm>
4826+
<listitem>
4827+
<para>
4828+
This allows us to tuen on/off database privilege checks on large
4829+
objects. In the 8.4.x series and earlier release do not have
4830+
privilege checks on large object in most cases.
4831+
4832+
So, turning the <varname>lo_compat_privileges</varname> off means
4833+
the large object feature performs in compatible mode.
4834+
</para>
4835+
<para>
4836+
Please note that it is not equivalent to disable all the security
4837+
checks corresponding to large objects.
4838+
For example, the <literal>lo_import()</literal> and
4839+
<literal>lo_export()</literal> need superuser privileges independent
4840+
from this setting as prior versions were doing.
4841+
</para>
4842+
<para>
4843+
It is <literal>off</literal> by default.
4844+
</para>
4845+
</listitem>
4846+
</varlistentry>
4847+
48194848
<varlistentry id="guc-sql-inheritance" xreflabel="sql_inheritance">
48204849
<term><varname>sql_inheritance</varname> (<type>boolean</type>)</term>
48214850
<indexterm>

‎doc/src/sgml/lobj.sgml

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@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/lobj.sgml,v 1.49 2008/12/07 23:46:39 alvherre Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/lobj.sgml,v 1.50 2009/12/11 03:34:55 itagaki Exp $ -->
22

33
<chapter id="largeObjects">
44
<title id="largeObjects-title">Large Objects</title>
@@ -441,6 +441,57 @@ SELECT lo_export(image.raster, '/tmp/motd') FROM image
441441
The client-side functions can be used by any
442442
<productname>PostgreSQL</productname> user.
443443
</para>
444+
445+
<sect2 id="lo-func-privilege">
446+
<title>Large object and privileges</title>
447+
<para>
448+
Note that access control feature was not supported in the 8.4.x series
449+
and earlier release.
450+
Also see the <xref linkend="guc-lo-compat-privileges"> compatibility
451+
option.
452+
</para>
453+
<para>
454+
Now it supports access controls on large objects, and allows the owner
455+
of large objects to set up access rights using
456+
<xref linkend="sql-grant" endterm="sql-grant-title"> and
457+
<xref linkend="sql-revoke" endterm="sql-revoke-title"> statement.
458+
</para>
459+
<para>
460+
Two permissions are defined on the large object class.
461+
These are checked only when <xref linkend="guc-lo-compat-privileges">
462+
option is disabled.
463+
</para>
464+
<para>
465+
The first is <literal>SELECT</literal>.
466+
It is required on <function>loread()</function> function.
467+
Note that when we open large object with read-only mode, we can see
468+
a static image even if other concurrent transaction modified the
469+
same large object.
470+
This principle is also applied on the access rights of large objects.
471+
Even if a transaction modified access rights and commit it, it is
472+
not invisible from other transaction which already opened the large
473+
object.
474+
</para>
475+
<para>
476+
The second is <literal>UPDATE</literal>.
477+
It is required on <function>lowrite()</function> function and
478+
<function>lo_truncate()</function> function.
479+
</para>
480+
<para>
481+
In addition, <function>lo_unlink()</function> function,
482+
<command>COMMENT ON</command> and <command>ALTER LARGE OBJECT</command>
483+
statements needs ownership of the large object to be accessed.
484+
</para>
485+
<para>
486+
You may wonder why <literal>SELECT</literal> is not checked on the
487+
<function>lo_export()</function> function or <literal>UPDATE</literal>
488+
is not checked on the <function>lo_import</function> function.
489+
490+
These functions originally require database superuser privilege,
491+
and it allows to bypass the default database privilege checks,
492+
so we don't need to check an obvious test twice.
493+
</para>
494+
</sect2>
444495
</sect1>
445496

446497
<sect1 id="lo-examplesect">

‎doc/src/sgml/ref/allfiles.sgml

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<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.76 2009/10/05 19:24:33 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/allfiles.sgml,v 1.77 2009/12/11 03:34:55 itagaki Exp $
33
PostgreSQL documentation
44
Complete list of usable sgml source files in this directory.
55
-->
@@ -16,6 +16,7 @@ Complete list of usable sgml source files in this directory.
1616
<!entity alterGroup system "alter_group.sgml">
1717
<!entity alterIndex system "alter_index.sgml">
1818
<!entity alterLanguage system "alter_language.sgml">
19+
<!entity alterLargeObject system "alter_large_object.sgml">
1920
<!entity alterOperator system "alter_operator.sgml">
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<!entity alterOperatorClass system "alter_opclass.sgml">
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<!entity alterOperatorFamily system "alter_opfamily.sgml">
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1+
<refentry id="SQL-ALTERLARGEOBJECT">
2+
<refmeta>
3+
<refentrytitle id="SQL-ALTERLARGEOBJECT-title">ALTER LARGE OBJECT</refentrytitle>
4+
<manvolnum>7</manvolnum>
5+
<refmiscinfo>SQL - Language Statements</refmiscinfo>
6+
</refmeta>
7+
8+
<refnamediv>
9+
<refname>ALTER LARGE OBJECT</refname>
10+
<refpurpose>change the definition of a large object</refpurpose>
11+
</refnamediv>
12+
13+
<indexterm zone="sql-alterlargeobject">
14+
<primary>ALTER LARGE OBJECT</primary>
15+
</indexterm>
16+
17+
<refsynopsisdiv>
18+
<synopsis>
19+
ALTER LARGE OBJECT <replaceable class="PARAMETER">large_object_oid</replaceable> OWNER TO <replaceable>new_owner</replaceable>
20+
</synopsis>
21+
</refsynopsisdiv>
22+
23+
<refsect1>
24+
<title>Description</title>
25+
26+
<para>
27+
<command>ALTER LARGE OBJECT</command> changes the definition of a
28+
large object. The only functionality is to assign a new owner.
29+
You must be superuser or owner of the large object to use
30+
<command>ALTER LARGE OBJECT</command>.
31+
</para>
32+
</refsect1>
33+
34+
<refsect1>
35+
<title>Parameters</title>
36+
37+
<variablelist>
38+
<varlistentry>
39+
<term><replaceable>large_object_oid</replaceable></term>
40+
<listitem>
41+
<para>
42+
OID of the large object to be altered
43+
</para>
44+
</listitem>
45+
</varlistentry>
46+
47+
<varlistentry>
48+
<term><replaceable>new_owner</replaceable></term>
49+
<listitem>
50+
<para>
51+
The new owner of the large object
52+
</para>
53+
</listitem>
54+
</varlistentry>
55+
</variablelist>
56+
</refsect1>
57+
58+
<refsect1>
59+
<title>Compatibility</title>
60+
61+
<para>
62+
There is no <command>ALTER LARGE OBJECT</command> statement in the SQL
63+
standard.
64+
</para>
65+
</refsect1>
66+
67+
<refsect1>
68+
<title>See Also</title>
69+
70+
<simplelist type="inline">
71+
<member><xref linkend="largeObjects" endterm="largeObjects-title"></member>
72+
</simplelist>
73+
</refsect1>
74+
75+
</refentry>

‎doc/src/sgml/ref/grant.sgml

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<!--
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$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.79 2009/10/12 20:39:39 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/grant.sgml,v 1.80 2009/12/11 03:34:55 itagaki Exp $
33
PostgreSQL documentation
44
-->
55

@@ -59,6 +59,10 @@ GRANT { USAGE | ALL [ PRIVILEGES ] }
5959
ON LANGUAGE <replaceable>lang_name</replaceable> [, ...]
6060
TO { [ GROUP ] <replaceable class="PARAMETER">role_name</replaceable> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
6161

62+
GRANT { { SELECT | UPDATE } [,...] | ALL [ PRIVILEGES ] }
63+
ON LARGE OBJECT <replaceable class="PARAMETER">loid</replaceable> [, ...]
64+
TO { [ GROUP ] <replaceable class="PARAMETER">rolename</replaceable> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
65+
6266
GRANT { { CREATE | USAGE } [,...] | ALL [ PRIVILEGES ] }
6367
ON SCHEMA <replaceable>schema_name</replaceable> [, ...]
6468
TO { [ GROUP ] <replaceable class="PARAMETER">role_name</replaceable> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
@@ -170,6 +174,8 @@ GRANT <replaceable class="PARAMETER">role_name</replaceable> [, ...] TO <replace
170174
<xref linkend="sql-delete" endterm="sql-delete-title">.
171175
For sequences, this privilege also allows the use of the
172176
<function>currval</function> function.
177+
For large objects, this privilege also allows to read from
178+
the target large object.
173179
</para>
174180
</listitem>
175181
</varlistentry>
@@ -203,6 +209,8 @@ GRANT <replaceable class="PARAMETER">role_name</replaceable> [, ...] TO <replace
203209
<literal>SELECT</literal> privilege. For sequences, this
204210
privilege allows the use of the <function>nextval</function> and
205211
<function>setval</function> functions.
212+
For large objects, this privilege also allows to write or truncate
213+
on the target large object.
206214
</para>
207215
</listitem>
208216
</varlistentry>

‎doc/src/sgml/ref/revoke.sgml

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<!--
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$PostgreSQL: pgsql/doc/src/sgml/ref/revoke.sgml,v 1.53 2009/10/12 20:39:39 tgl Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/ref/revoke.sgml,v 1.54 2009/12/11 03:34:55 itagaki Exp $
33
PostgreSQL documentation
44
-->
55

@@ -75,6 +75,12 @@ REVOKE [ GRANT OPTION FOR ]
7575
FROM { [ GROUP ] <replaceable class="PARAMETER">role_name</replaceable> | PUBLIC } [, ...]
7676
[ CASCADE | RESTRICT ]
7777

78+
REVOKE [ GRANT OPTION FOR ]
79+
{ { SELECT | UPDATE } [,...] | ALL [ PRIVILEGES ] }
80+
ON LARGE OBJECT <replaceable class="PARAMETER">loid</replaceable> [, ...]
81+
FROM { [ GROUP ] <replaceable class="PARAMETER">rolename</replaceable> | PUBLIC } [, ...]
82+
[ CASCADE | RESTRICT ]
83+
7884
REVOKE [ GRANT OPTION FOR ]
7985
{ { CREATE | USAGE } [,...] | ALL [ PRIVILEGES ] }
8086
ON SCHEMA <replaceable>schema_name</replaceable> [, ...]

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