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Postgres FD Implementation
Commit 840b7f52 authored by Tom Lane's avatar Tom Lane
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Update administrator's guide chapters for ROLEs patch.

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doc/src/sgml/client-auth.sgml
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<!--
$PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.82 2005/06/27 02:04:23 neilc Exp $
$PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.83 2005/08/14 23:35:37 tgl Exp $
-->
<chapter id="client-authentication">
......@@ -11,7 +11,7 @@ $PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.82 2005/06/27 02:04:23 neil
<para>
When a client application connects to the database server, it
specifies which <productname>PostgreSQL</productname> user name it
specifies which <productname>PostgreSQL</productname> database user name it
wants to connect as, much the same way one logs into a Unix computer
as a particular user. Within the SQL environment the active database
user name determines access privileges to database objects &mdash; see
......@@ -19,12 +19,22 @@ $PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.82 2005/06/27 02:04:23 neil
essential to restrict which database users can connect.
</para>
<note>
<para>
As explained in <xref linkend="user-manag">,
<productname>PostgreSQL</productname> actually does privilege
management in terms of <quote>roles</>. In this chapter, we
consistently use <firstterm>database user</> to mean <quote>role with the
<literal>LOGIN</> privilege</quote>.
</para>
</note>
<para>
<firstterm>Authentication</firstterm> is the process by which the
database server establishes the identity of the client, and by
extension determines whether the client application (or the user
who runs the client application) is permitted to connect with the
user name that was requested.
database user name that was requested.
</para>
<para>
......@@ -35,7 +45,7 @@ $PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.82 2005/06/27 02:04:23 neil
</para>
<para>
<productname>PostgreSQL</productname> user names are logically
<productname>PostgreSQL</productname> database user names are logically
separate from user names of the operating system in which the server
runs. If all the users of a particular server also have accounts on
the server's machine, it makes sense to assign database user names
......@@ -88,13 +98,13 @@ $PostgreSQL: pgsql/doc/src/sgml/client-auth.sgml,v 1.82 2005/06/27 02:04:23 neil
<para>
A record may have one of the seven formats
<synopsis>
local <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>authentication-method</replaceable> <optional><replaceable>authentication-option</replaceable></optional>
local <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>CIDR-address</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
host <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
hostssl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable> <replaceable>IP-address</replaceable> <replaceable>IP-mask</replaceable> <replaceable>auth-method</replaceable> <optional><replaceable>auth-option</replaceable></optional>
</synopsis>
The meaning of the fields is as follows:
......@@ -165,16 +175,18 @@ hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable>
<term><replaceable>database</replaceable></term>
<listitem>
<para>
Specifies which databases this record matches. The value
Specifies which database names this record matches. The value
<literal>all</literal> specifies that it matches all databases.
The value <literal>sameuser</> specifies that the record
matches if the requested database has the same name as the
requested user. The value <literal>samegroup</> specifies that
the requested user must be a member of the group with the same
name as the requested database. Otherwise, this is the name of
requested user. The value <literal>samerole</> specifies that
the requested user must be a member of the role with the same
name as the requested database. (<literal>samegroup</> is an
obsolete but still accepted spelling of <literal>samerole</>.)
Otherwise, this is the name of
a specific <productname>PostgreSQL</productname> database.
Multiple database names can be supplied by separating them with
commas. A file containing database names can be specified by
commas. A separate file containing database names can be specified by
preceding the file name with <literal>@</>.
</para>
</listitem>
......@@ -184,13 +196,17 @@ hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable>
<term><replaceable>user</replaceable></term>
<listitem>
<para>
Specifies which <productname>PostgreSQL</> users this record
Specifies which database user names this record
matches. The value <literal>all</literal> specifies that it
matches all users. Otherwise, this is the name of a specific
<productname>PostgreSQL</productname> user. Multiple user names
can be supplied by separating them with commas. Group names can
be specified by preceding the group name with <literal>+</>. A
file containing user names can be specified by preceding the
matches all users. Otherwise, this is either the name of a specific
database user, or a group name preceded by <literal>+</>.
(Recall that there is no real distinction between users and groups
in <productname>PostgreSQL</>; a <literal>+</> mark really means
<quote>match any of the roles that are directly or indirectly members
of this role</>, while a name without a <literal>+</> mark matches
only that specific role.)
Multiple user names can be supplied by separating them with commas.
A separate file containing user names can be specified by preceding the
file name with <literal>@</>.
</para>
</listitem>
......@@ -257,7 +273,7 @@ hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable>
</varlistentry>
<varlistentry>
<term><replaceable>authentication-method</replaceable></term>
<term><replaceable>auth-method</replaceable></term>
<listitem>
<para>
Specifies the authentication method to use when connecting via
......@@ -369,7 +385,7 @@ hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable>
</varlistentry>
<varlistentry>
<term><replaceable>authentication-option</replaceable></term>
<term><replaceable>auth-option</replaceable></term>
<listitem>
<para>
The meaning of this optional field depends on the chosen
......@@ -424,7 +440,7 @@ hostnossl <replaceable>database</replaceable> <replaceable>user</replaceable>
<title>Example <filename>pg_hba.conf</filename> entries</title>
<programlisting>
# Allow any user on the local system to connect to any database under
# any user name using Unix-domain sockets (the default for local
# any database user name using Unix-domain sockets (the default for local
# connections).
#
# TYPE DATABASE USER CIDR-ADDRESS METHOD
......@@ -445,7 +461,7 @@ host all all 127.0.0.1 255.255.255.255 trust
# the connection (typically the Unix user name).
#
# TYPE DATABASE USER CIDR-ADDRESS METHOD
host postgres all 192.168.93.0/24 ident sameuser
host postgres all 192.168.93.0/24 ident sameuser
# Allow a user from host 192.168.12.10 to connect to database
# "postgres" if the user's password is correctly supplied.
......@@ -474,10 +490,10 @@ host all all 192.168.0.0/16 ident omicron
# If these are the only three lines for local connections, they will
# allow local users to connect only to their own databases (databases
# with the same name as their user name) except for administrators and
# members of group "support" who may connect to all databases. The file
# $PGDATA/admins contains a list of user names. Passwords are required in
# all cases.
# with the same name as their database user name) except for administrators
# and members of role "support", who may connect to all databases. The file
# $PGDATA/admins contains a list of names of administrators. Passwords
# are required in all cases.
#
# TYPE DATABASE USER CIDR-ADDRESS METHOD
local sameuser all md5
......@@ -487,7 +503,7 @@ local all +support md5
# The last two lines above can be combined into a single line:
local all @admins,+support md5
# The database column can also use lists and file names, but not groups:
# The database column can also use lists and file names:
local db1,db2,@demodbs all md5
</programlisting>
</example>
......@@ -506,7 +522,7 @@ local db1,db2,@demodbs all md5
When <literal>trust</> authentication is specified,
<productname>PostgreSQL</productname> assumes that anyone who can
connect to the server is authorized to access the database with
whatever database user they specify (including the database superuser).
whatever database user name they specify (including superusers).
Of course, restrictions made in the <literal>database</> and
<literal>user</> columns still apply.
This method should only be used when there is adequate
......@@ -564,8 +580,9 @@ local db1,db2,@demodbs all md5
The password-based authentication methods are <literal>md5</>,
<literal>crypt</>, and <literal>password</>. These methods operate
similarly except for the way that the password is sent across the
connection. However, <literal>crypt</> does not allow encrypted
passwords to be stored in <structname>pg_shadow</structname>.
connection: respectively, MD5-hashed, crypt-encrypted, and clear-text.
A limitation is that the <literal>crypt</> method does not work with
passwords that have been encrypted in <structname>pg_authid</structname>.
</para>
<para>
......@@ -573,15 +590,16 @@ local db1,db2,@demodbs all md5
<quote>sniffing</> attacks then <literal>md5</> is preferred, with
<literal>crypt</> a second choice if you must support pre-7.2
clients. Plain <literal>password</> should especially be avoided for
connections over the open Internet (unless you use <acronym>SSL</acronym>, SSH, or
other communications security wrappers around the connection).
connections over the open Internet (unless you use <acronym>SSL</acronym>,
<acronym>SSH</>, or another
communications security wrapper around the connection).
</para>
<para>
<productname>PostgreSQL</productname> database passwords are
separate from operating system user passwords. The password for
each database user is stored in the <literal>pg_shadow</> system
catalog table. Passwords can be managed with the SQL commands
each database user is stored in the <literal>pg_authid</> system
catalog. Passwords can be managed with the SQL commands
<xref linkend="sql-createuser" endterm="sql-createuser-title"> and
<xref linkend="sql-alteruser" endterm="sql-alteruser-title">,
e.g., <userinput>CREATE USER foo WITH PASSWORD 'secret';</userinput>.
......@@ -607,41 +625,44 @@ local db1,db2,@demodbs all md5
<ulink url="http://www.nrl.navy.mil/CCS/people/kenh/kerberos-faq.html">
Kerberos <acronym>FAQ</></ulink> or
<ulink url="http://web.mit.edu/kerberos/www/">MIT Kerberos page</ulink>
can be a good starting point for exploration.
can be good starting points for exploration.
Several sources for <productname>Kerberos</> distributions exist.
</para>
<para>
<productname>PostgreSQL</> supports Kerberos version 5, and it has
to be enabled at build time. See
<xref linkend="installation"> for more information.
<productname>PostgreSQL</> supports Kerberos version 5. Kerberos
support has to be enabled when <productname>PostgreSQL</> is built;
see <xref linkend="installation"> for more information.
</para>
<para>
<productname>PostgreSQL</> operates like a normal Kerberos service.
The name of the service principal is
<literal><replaceable>servicename</>/<replaceable>hostname</>@<replaceable>realm</></literal>.
</para>
<para>
</para>
<para>
<replaceable>servicename</> can be set on the server side using the
<xref linkend="guc-krb-srvname"> configuration parameter, and on the
client side using the krbsrvname connection parameter. (See also <xref linkend="libpq-connect">.). The installation default can be changed from the default
<literal>postgres</literal> at build time using
<literal>./configure --with-krb-srvnam=whatever</>). In most environments,
this parameter never needs to be changed. However, to support multiple
<productname>PostgreSQL</> installations on the same host it is necessary.
Some Kerberos implementations may also require a different service name,
such as Microsoft Active Directory which requires the service name
to be in uppercase (<literal>POSTGRES</literal>).
</para>
<para>
client side using the <literal>krbsrvname</> connection parameter. (See
also <xref linkend="libpq-connect">.) The installation default can be
changed from the default <literal>postgres</literal> at build time using
<literal>./configure --with-krb-srvnam=whatever</>. In most environments,
this parameter never needs to be changed. However, to support multiple
<productname>PostgreSQL</> installations on the same host it is necessary.
Some Kerberos implementations may also require a different service name,
such as Microsoft Active Directory which requires the service name
to be in uppercase (<literal>POSTGRES</literal>).
</para>
<para>
<replaceable>hostname</> is the fully qualified host name of the
server machine. The service principal's realm is the preferred realm
of the server machine.
</para>
<para>
Client principals must have their <productname>PostgreSQL</> user
Client principals must have their <productname>PostgreSQL</> database user
name as their first component, for example
<literal>pgusername/otherstuff@realm</>. At present the realm of
the client is not checked by <productname>PostgreSQL</>; so if you
......@@ -661,9 +682,9 @@ local db1,db2,@demodbs all md5
</para>
<para>
The keytab file is generated in the Kerberos system, see the
Kerberos documentation for details. The following example is
for MIT-compatible Kerberos 5 implementations:
The keytab file is generated by the Kerberos software; see the
Kerberos documentation for details. The following example is
for MIT-compatible Kerberos 5 implementations:
<screen>
<prompt>kadmin% </><userinput>ank -randkey postgres/server.my.domain.org</>
<prompt>kadmin% </><userinput>ktadd -k krb5.keytab postgres/server.my.domain.org</>
......@@ -672,10 +693,10 @@ local db1,db2,@demodbs all md5
<para>
When connecting to the database make sure you have a ticket for a
principal matching the requested database user name. An example: For
principal matching the requested database user name. For example, for
database user name <literal>fred</>, both principal
<literal>fred@EXAMPLE.COM</> and
<literal>fred/users.example.com@EXAMPLE.COM</> can be used to
<literal>fred/users.example.com@EXAMPLE.COM</> could be used to
authenticate to the database server.
</para>
......@@ -900,7 +921,7 @@ FATAL: no pg_hba.conf entry for host "123.123.123.123", user "andym", database
This is what you are most likely to get if you succeed in contacting
the server, but it does not want to talk to you. As the message
suggests, the server refused the connection request because it found
no authorizing entry in its <filename>pg_hba.conf</filename>
no matching entry in its <filename>pg_hba.conf</filename>
configuration file.
</para>
......
doc/src/sgml/manage-ag.sgml
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<!--
$PostgreSQL: pgsql/doc/src/sgml/manage-ag.sgml,v 2.42 2005/06/21 04:02:30 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/manage-ag.sgml,v 2.43 2005/08/14 23:35:37 tgl Exp $
-->
<chapter id="managing-databases">
......@@ -94,7 +94,7 @@ SELECT datname FROM pg_database;
CREATE DATABASE <replaceable>name</>;
</synopsis>
where <replaceable>name</> follows the usual rules for
<acronym>SQL</acronym> identifiers. The current user automatically
<acronym>SQL</acronym> identifiers. The current role automatically
becomes the owner of the new database. It is the privilege of the
owner of a database to remove it later on (which also removes all
the objects in it, even if they have a different owner).
......@@ -102,7 +102,7 @@ CREATE DATABASE <replaceable>name</>;
<para>
The creation of databases is a restricted operation. See <xref
linkend="user-attributes"> for how to grant permission.
linkend="role-attributes"> for how to grant permission.
</para>
<para>
......@@ -158,18 +158,18 @@ createdb <replaceable class="parameter">dbname</replaceable>
<para>
Sometimes you want to create a database for someone else. That
user should become the owner of the new database, so he can
role should become the owner of the new database, so he can
configure and manage it himself. To achieve that, use one of the
following commands:
<programlisting>
CREATE DATABASE <replaceable>dbname</> OWNER <replaceable>username</>;
CREATE DATABASE <replaceable>dbname</> OWNER <replaceable>rolename</>;
</programlisting>
from the SQL environment, or
<programlisting>
createdb -O <replaceable>username</> <replaceable>dbname</>
createdb -O <replaceable>rolename</> <replaceable>dbname</>
</programlisting>
You must be a superuser to be allowed to create a database for
someone else.
someone else (that is, for a role you are not a member of).
</para>
</sect1>
......@@ -327,7 +327,7 @@ ALTER DATABASE mydb SET geqo TO off;
<synopsis>
DROP DATABASE <replaceable>name</>;
</synopsis>
Only the owner of the database (i.e., the user that created it), or
Only the owner of the database, or
a superuser, can drop a database. Dropping a database removes all objects
that were
contained within the database. The destruction of a database cannot
......
doc/src/sgml/ref/create_role.sgml
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<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_role.sgml,v 1.2 2005/07/31 17:19:17 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_role.sgml,v 1.3 2005/08/14 23:35:38 tgl Exp $
PostgreSQL documentation
-->
......@@ -141,7 +141,7 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
<para>
These clauses determine whether a role <quote>inherits</> the
privileges of roles it is a member of.
A role with <literal>INHERIT</literal> privilege can automatically
A role with the <literal>INHERIT</literal> attribute can automatically
use whatever database privileges have been granted to all roles
it is directly or indirectly a member of.
Without <literal>INHERIT</literal>, membership in another role
......@@ -162,7 +162,7 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
These clauses determine whether a role is allowed to log in;
that is, whether the role can be given as the initial session
authorization name during client connection. A role having
<literal>LOGIN</literal> privilege can be thought of as a user.
the <literal>LOGIN</literal> attribute can be thought of as a user.
Roles without this attribute are useful for managing database
privileges, but are not users in the usual sense of the word.
If not specified,
......@@ -188,7 +188,7 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
<listitem>
<para>
Sets the role's password. (A password is only of use for
roles having <literal>LOGIN</literal> privilege, but you can
roles having the <literal>LOGIN</literal> attribute, but you can
nonetheless define one for roles without it.)
If you do not plan to use password
authentication you can omit this option.
......@@ -325,7 +325,19 @@ where <replaceable class="PARAMETER">option</replaceable> can be:
</para>
<para>
<literal>INHERIT</> privilege is the default for reasons of backwards
The <literal>INHERIT</> attribute governs inheritance of grantable
privileges (that is, access privileges for database objects and role
memberships). It does not apply to the special role attributes set by
<command>CREATE ROLE</> and <command>ALTER ROLE</>. For example, being
a member of a role with <literal>CREATEDB</> privilege does not immediately
grant the ability to create databases, even if <literal>INHERIT</> is set;
it would be necessary to become that role via
<xref linkend="SQL-SET-ROLE" endterm="SQL-SET-ROLE-title"> before
creating a database.
</para>
<para>
The <literal>INHERIT</> attribute is the default for reasons of backwards
compatibility: in prior releases of <productname>PostgreSQL</productname>,
users always had access to all privileges of groups they were members of.
However, <literal>NOINHERIT</> provides a closer match to the semantics
......
doc/src/sgml/user-manag.sgml
View file @ 840b7f52
<!--
$PostgreSQL: pgsql/doc/src/sgml/user-manag.sgml,v 1.29 2005/03/25 16:38:58 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/user-manag.sgml,v 1.30 2005/08/14 23:35:37 tgl Exp $
-->
<chapter id="user-manag">
<title>Database Users and Privileges</title>
<title>Database Roles and Privileges</title>
<para>
Every database cluster contains a set of database users. Those
users are separate from the users managed by the operating system on
which the server runs. Users own database objects (for example,
tables) and can assign privileges on those objects to other users to
control who has access to which object.
<productname>PostgreSQL</productname> manages database access permissions
using the concept of <firstterm>roles</>. A role can be thought of as
either a database user, or a group of database users, depending on how
the role is set up. Roles can own database objects (for example,
tables) and can assign privileges on those objects to other roles to
control who has access to which objects. Furthermore, it is possible
to grant <firstterm>membership</> in a role to another role, thus
allowing the member role use of privileges assigned to the role it is
a member of.
</para>
<para>
This chapter describes how to create and manage users and introduces
The concept of roles subsumes the concepts of <quote>users</> and
<quote>groups</>. In <productname>PostgreSQL</productname> versions
before 8.1, users and groups were distinct kinds of entities, but now
there are only roles. Any role can act as a user, a group, or both.
</para>
<para>
This chapter describes how to create and manage roles and introduces
the privilege system. More information about the various types of
database objects and the effects of privileges can be found in <xref linkend="ddl">.
database objects and the effects of privileges can be found in
<xref linkend="ddl">.
</para>
<sect1 id="database-users">
<title>Database Users</title>
<sect1 id="database-roles">
<title>Database Roles</title>
<indexterm zone="database-users">
<indexterm zone="database-roles">
<primary>role</primary>
</indexterm>
<indexterm zone="database-roles">
<primary>user</primary>
</indexterm>
<indexterm>
<primary>CREATE USER</primary>
<primary>CREATE ROLE</primary>
</indexterm>
<indexterm>
<primary>DROP USER</primary>
<primary>DROP ROLE</primary>
</indexterm>
<para>
Database users are conceptually completely separate from
Database roles are conceptually completely separate from
operating system users. In practice it might be convenient to
maintain a correspondence, but this is not required. Database user
names are global across a database cluster installation (and not
per individual database). To create a user use the <xref
linkend="sql-createuser" endterm="sql-createuser-title"> SQL command:
maintain a correspondence, but this is not required. Database roles
are global across a database cluster installation (and not
per individual database). To create a role use the <xref
linkend="sql-createrole" endterm="sql-createrole-title"> SQL command:
<synopsis>
CREATE USER <replaceable>name</replaceable>;
CREATE ROLE <replaceable>name</replaceable>;
</synopsis>
<replaceable>name</replaceable> follows the rules for SQL
identifiers: either unadorned without special characters, or
double-quoted. To remove an existing user, use the analogous
<xref linkend="sql-dropuser" endterm="sql-dropuser-title"> command:
double-quoted. (In practice, you will usually want to add additional
options, such as <literal>LOGIN</>, to the command. More details appear
below.) To remove an existing role, use the analogous
<xref linkend="sql-droprole" endterm="sql-droprole-title"> command:
<synopsis>
DROP USER <replaceable>name</replaceable>;
DROP ROLE <replaceable>name</replaceable>;
</synopsis>
</para>
......@@ -73,69 +91,93 @@ dropuser <replaceable>name</replaceable>
</para>
<para>
To determine the set of existing users, examine the <structname>pg_user</>
To determine the set of existing roles, examine the <structname>pg_roles</>
system catalog, for example
<synopsis>
SELECT usename FROM pg_user;
SELECT rolname FROM pg_roles;
</synopsis>
The <xref linkend="app-psql"> program's <literal>\du</> meta-command
is also useful for listing the existing users.
is also useful for listing the existing roles.
</para>
<para>
In order to bootstrap the database system, a freshly initialized
system always contains one predefined user. This user will have the
fixed ID 1, and by default (unless altered when running
system always contains one predefined role. This role is always
a <quote>superuser</>, and by default (unless altered when running
<command>initdb</command>) it will have the same name as the
operating system user that initialized the database
cluster. Customarily, this user will be named
<literal>postgres</literal>. In order to create more users you
first have to connect as this initial user.
cluster. Customarily, this role will be named
<literal>postgres</literal>. In order to create more roles you
first have to connect as this initial role.
</para>
<para>
Exactly one user identity is active for a connection to the
database server. The user name to use for a particular database
Every connection to the database server is made in the name of some
particular role, and this role determines the initial access privileges for
commands issued on that connection.
The role name to use for a particular database
connection is indicated by the client that is initiating the
connection request in an application-specific fashion. For example,
the <command>psql</command> program uses the
<option>-U</option> command line option to indicate the user to
<option>-U</option> command line option to indicate the role to
connect as. Many applications assume the name of the current
operating system user by default (including
<command>createuser</> and <command>psql</>). Therefore it
is convenient to maintain a naming correspondence between the two
user sets.
is often convenient to maintain a naming correspondence between
roles and operating system users.
</para>
<para>
The set of database users a given client connection may connect as
The set of database roles a given client connection may connect as
is determined by the client authentication setup, as explained in
<xref linkend="client-authentication">. (Thus, a client is not
necessarily limited to connect as the user with the same name as
necessarily limited to connect as the role with the same name as
its operating system user, just as a person's login name
need not match her real name.) Since the user
need not match her real name.) Since the role
identity determines the set of privileges available to a connected
client, it is important to carefully configure this when setting up
a multiuser environment.
</para>
</sect1>
<sect1 id="user-attributes">
<title>User Attributes</title>
<sect1 id="role-attributes">
<title>Role Attributes</title>
<para>
A database user may have a number of attributes that define its
A database role may have a number of attributes that define its
privileges and interact with the client authentication system.
<variablelist>
<varlistentry>
<term>superuser<indexterm><primary>superuser</></></term>
<term>login privilege<indexterm><primary>login privilege</></></term>
<listitem>
<para>
Only roles that have the <literal>LOGIN</> attribute can be used
as the initial role name for a database connection. A role with
the <literal>LOGIN</> attribute can be considered the same thing
as a <quote>database user</>. To create a role with login privilege,
use either
<programlisting>
CREATE ROLE <replaceable>name</replaceable> LOGIN;
CREATE USER <replaceable>name</replaceable>;
</programlisting>
(<command>CREATE USER</> is equivalent to <command>CREATE ROLE</>
except that <command>CREATE USER</> assumes <literal>LOGIN</> by
default, while <command>CREATE ROLE</> does not.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>superuser status<indexterm><primary>superuser</></></term>
<listitem>
<para>
A database superuser bypasses all permission checks. Also,
only a superuser can create new users. To create a database
superuser, use <literal>CREATE USER <replaceable>name</replaceable>
CREATEUSER</literal>.
A database superuser bypasses all permission checks. This is a
dangerous privilege and should not be used carelessly; it is best
to do most of your work as a role that is not a superuser.
To create a new database superuser, use <literal>CREATE ROLE
<replaceable>name</replaceable> SUPERUSER</literal>. You must do
this as a role that is already a superuser.
</para>
</listitem>
</varlistentry>
......@@ -144,14 +186,30 @@ SELECT usename FROM pg_user;
<term>database creation<indexterm><primary>database</><secondary>privilege to create</></></term>
<listitem>
<para>
A user must be explicitly given permission to create databases
A role must be explicitly given permission to create databases
(except for superusers, since those bypass all permission
checks). To create such a user, use <literal>CREATE USER
checks). To create such a role, use <literal>CREATE ROLE
<replaceable>name</replaceable> CREATEDB</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>role creation<indexterm><primary>role</><secondary>privilege to create</></></term>
<listitem>
<para>
A role must be explicitly given permission to create more roles
(except for superusers, since those bypass all permission
checks). To create such a role, use <literal>CREATE ROLE
<replaceable>name</replaceable> CREATEROLE</literal>.
A role with <literal>CREATEROLE</> privilege can alter and drop
other roles, too. However, to alter or drop a superuser role,
superuser status is required; <literal>CREATEROLE</> is not sufficient
for that.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>password<indexterm><primary>password</></></term>
<listitem>
......@@ -161,79 +219,159 @@ SELECT usename FROM pg_user;
to the database. The <option>password</>,
<option>md5</>, and <option>crypt</> authentication methods
make use of passwords. Database passwords are separate from
operating system passwords. Specify a password upon user
creation with <literal>CREATE USER
operating system passwords. Specify a password upon role
creation with <literal>CREATE ROLE
<replaceable>name</replaceable> PASSWORD '<replaceable>string</>'</literal>.
</para>
</listitem>
</varlistentry>
</variablelist>
A user's attributes can be modified after creation with
<command>ALTER USER</command>.<indexterm><primary>ALTER USER</></>
See the reference pages for the <xref linkend="sql-createuser"
endterm="sql-createuser-title"> and <xref linkend="sql-alteruser"
endterm="sql-alteruser-title"> commands for details.
A role's attributes can be modified after creation with
<command>ALTER ROLE</command>.<indexterm><primary>ALTER ROLE</></>
See the reference pages for the <xref linkend="sql-createrole"
endterm="sql-createrole-title"> and <xref linkend="sql-alterrole"
endterm="sql-alterrole-title"> commands for details.
</para>
<para>
A user can also set personal defaults for many of the run-time
A role can also have role-specific defaults for many of the run-time
configuration settings described in <xref
linkend="runtime-config">. For example, if for some reason you
want to disable index scans (hint: not a good idea) anytime you
connect, you can use
<programlisting>
ALTER USER myname SET enable_indexscan TO off;
ALTER ROLE myname SET enable_indexscan TO off;
</programlisting>
This will save the setting (but not set it immediately). In
subsequent connections by this user it will appear as though
subsequent connections by this role it will appear as though
<literal>SET enable_indexscan TO off;</literal> had been executed
just before the session started.
You can still alter this setting during the session; it will only
be the default. To undo any such setting, use <literal>ALTER USER
<replaceable>username</> RESET <replaceable>varname</>;</literal>.
be the default. To remove a role-specific default setting, use
<literal>ALTER ROLE <replaceable>rolename</> RESET <replaceable>varname</>;</literal>.
Note that role-specific defaults attached to roles without
<literal>LOGIN</> privilege are fairly useless, since they will never
be invoked.
</para>
</sect1>
<sect1 id="groups">
<title>Groups</title>
<sect1 id="role-membership">
<title>Role Membership</title>
<indexterm zone="groups">
<primary>group</primary>
<indexterm zone="role-membership">
<primary>role</><secondary>membership in</>
</indexterm>
<para>
As in Unix, groups are a way of logically grouping users to ease
management of privileges: privileges can be granted to, or revoked
from, a group as a whole. To create a group, use the <xref
linkend="sql-creategroup" endterm="sql-creategroup-title"> SQL command:
<synopsis>
CREATE GROUP <replaceable>name</replaceable>;
</synopsis>
It is frequently convenient to group users together to ease
management of privileges: that way, privileges can be granted to, or
revoked from, a group as a whole. In <productname>PostgreSQL</productname>
this is done by creating a role that represents the group, and then
granting <firstterm>membership</> in the group role to individual user
roles.
</para>
To add users to or remove users from an existing group, use <xref
linkend="sql-altergroup" endterm="sql-altergroup-title">:
<para>
To set up a group role, first create the role:
<synopsis>
ALTER GROUP <replaceable>name</replaceable> ADD USER <replaceable>uname1</replaceable>, ... ;
ALTER GROUP <replaceable>name</replaceable> DROP USER <replaceable>uname1</replaceable>, ... ;
CREATE ROLE <replaceable>name</replaceable>;
</synopsis>
Typically a role being used as a group would not have the <literal>LOGIN</>
attribute, though you can set it if you wish.
</para>
To destroy a group, use <xref
linkend="sql-dropgroup" endterm="sql-dropgroup-title">:
<para>
Once the group role exists, you can add and remove members using the
<xref linkend="sql-grant" endterm="sql-grant-title"> and
<xref linkend="sql-revoke" endterm="sql-revoke-title"> commands:
<synopsis>
DROP GROUP <replaceable>name</replaceable>;
GRANT <replaceable>group_role</replaceable> TO <replaceable>role1</replaceable>, ... ;
REVOKE <replaceable>group_role</replaceable> FROM <replaceable>role1</replaceable>, ... ;
</synopsis>
This only drops the group, not its member users.
You can grant membership to other group roles, too (since there isn't
really any distinction between group roles and non-group roles). The
only restriction is that you can't set up circular membership loops.
</para>
<para>
To determine the set of existing groups, examine the <structname>pg_group</>
system catalog, for example
The members of a role can use the privileges of the group role in two
ways. First, every member of a group can explicitly do
<xref linkend="sql-set-role" endterm="sql-set-role-title"> to
temporarily <quote>become</> the group role. In this state, the
database session has access to the privileges of the group role rather
than the original login role, and any database objects created are
considered owned by the group role not the login role. Second, member
roles that have the <literal>INHERIT</> attribute automatically have use of
privileges of roles they are members of. As an example, suppose we have
done
<programlisting>
CREATE ROLE joe LOGIN INHERIT;
CREATE ROLE admin NOINHERIT;
CREATE ROLE wheel NOINHERIT;
GRANT admin TO joe;
GRANT wheel TO admin;
</programlisting>
Immediately after connecting as role <literal>joe</>, a database
session will have use of privileges granted directly to <literal>joe</>
plus any privileges granted to <literal>admin</>, because <literal>joe</>
<quote>inherits</> <literal>admin</>'s privileges. However, privileges
granted to <literal>wheel</> are not available, because even though
<literal>joe</> is indirectly a member of <literal>wheel</>, the
membership is via <literal>admin</> which has the <literal>NOINHERIT</>
attribute. After
<programlisting>
SET ROLE admin;
</programlisting>
the session would have use of only those privileges granted to
<literal>admin</>, and not those granted to <literal>joe</>. After
<programlisting>
SET ROLE wheel;
</programlisting>
the session would have use of only those privileges granted to
<literal>wheel</>, and not those granted to either <literal>joe</>
or <literal>admin</>. The original privilege state can be restored
with any of
<programlisting>
SET ROLE joe;
SET ROLE NONE;
RESET ROLE;
</programlisting>
</para>
<note>
<para>
The <command>SET ROLE</> command always allows selecting any role
that the original login role is directly or indirectly a member of.
Thus, in the above example, it is not necessary to become
<literal>admin</> before becoming <literal>wheel</>.
</para>
</note>
<note>
<para>
In the SQL standard, there is a clear distinction between users and roles,
and users do not automatically inherit privileges while roles do. This
behavior can be obtained in <productname>PostgreSQL</productname> by giving
roles being used as SQL roles the <literal>INHERIT</> attribute, while
giving roles being used as SQL users the <literal>NOINHERIT</> attribute.
However, <productname>PostgreSQL</productname> defaults to giving all roles
the <literal>INHERIT</> attribute, for backwards compatibility with pre-8.1
releases in which users always had use of permissions granted to groups
they were members of.
</para>
</note>
<para>
To destroy a group role, use <xref
linkend="sql-droprole" endterm="sql-droprole-title">:
<synopsis>
SELECT groname FROM pg_group;
DROP ROLE <replaceable>name</replaceable>;
</synopsis>
The <xref linkend="app-psql"> program's <literal>\dg</> meta-command
is also useful for listing the existing groups.
Any memberships in the group role are automatically revoked (but the
member roles are not otherwise affected). Note however that any objects
owned by the group role must first be dropped or reassigned to other
owners; and any permissions granted to the group role must be revoked.
</para>
</sect1>
......@@ -256,14 +394,12 @@ SELECT groname FROM pg_group;
<primary>REVOKE</primary>
</indexterm>
<remark>Being moved to the DDL chapter. Will eventually disappear here.</remark>
<para>
When an object is created, it is assigned an owner. The
owner is normally the user that executed the creation statement.
owner is normally the role that executed the creation statement.
For most kinds of objects, the initial state is that only the owner
(or a superuser) can do anything with the object. To allow
other users to use it, <firstterm>privileges</firstterm> must be
other roles to use it, <firstterm>privileges</firstterm> must be
granted.
There are several different kinds of privilege: <literal>SELECT</>,
<literal>INSERT</>, <literal>UPDATE</>, <literal>DELETE</>,
......@@ -277,25 +413,21 @@ SELECT groname FROM pg_group;
<para>
To assign privileges, the <command>GRANT</command> command is
used. So, if <literal>joe</literal> is an existing user, and
used. So, if <literal>joe</literal> is an existing role, and
<literal>accounts</literal> is an existing table, the privilege to
update the table can be granted with
<programlisting>
GRANT UPDATE ON accounts TO joe;
</programlisting>
To grant a privilege to a group, use
<programlisting>
GRANT SELECT ON accounts TO GROUP staff;
</programlisting>
The special name <literal>PUBLIC</literal> can
be used to grant a privilege to every user on the system. Writing
be used to grant a privilege to every role on the system. Writing
<literal>ALL</literal> in place of a specific privilege specifies that all
privileges that apply to the object will be granted.
</para>
<para>
To revoke a privilege, use the fittingly named
<command>REVOKE</command> command:
<xref linkend="sql-revoke" endterm="sql-revoke-title"> command:
<programlisting>
REVOKE ALL ON accounts FROM PUBLIC;
</programlisting>
......@@ -311,8 +443,10 @@ REVOKE ALL ON accounts FROM PUBLIC;
<para>
An object can be assigned to a new owner with an <command>ALTER</command>
command of the appropriate kind for the object. Only superusers can do
this.
command of the appropriate kind for the object. Superusers can always do
this; ordinary roles can only do it if they are both the current owner
of the object (or a member of the owning role) and a member of the new
owning role.
</para>
</sect1>
......
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