访问控制

介绍Pigsty中的访问控制模型

PostgreSQL提供了两类访问控制机制:认证(Authentication) 与 权限(Privileges)

Pigsty附带有基本的访问控制模型,足以覆盖绝大多数应用场景。

用户体系

Pigsty的默认权限系统包含四个默认用户与四类默认角色,覆盖绝大多数业务场景。

用户可以通过修改配置文件修改默认用户的名字,但默认角色的名字不建议新用户自行修改。

默认角色

Pigsty带有四个默认角色:

  • 只读角色(dbrole_readonly):只读
  • 读写角色(dbrole_readwrite):读写,继承dbrole_readonly
  • 管理角色(dbrole_admin):执行DDL变更,继承dbrole_readwrite
  • 离线角色(dbrole_offline):只读,用于执行慢查询/ETL/交互查询,仅允许在特定实例上访问。

默认用户

Pigsty带有四个默认用户:

  • 超级用户(postgres),数据库的拥有者与创建者,与操作系统用户一致
  • 复制用户(replicator),用于主从复制的用户。
  • 监控用户(dbuser_monitor),用于监控数据库指标的用户。
  • 管理员(dbuser_admin),执行日常管理操作与数据库变更。
name attr roles desc
dbrole_readonly Cannot login role for global readonly access
dbrole_readwrite Cannot login dbrole_readonly role for global read-write access
dbrole_offline Cannot login role for restricted read-only access (offline instance)
dbrole_admin Cannot login
Bypass RLS
pg_monitor
pg_signal_backend
dbrole_readwrite
role for object creation
postgres Superuser
Create role
Create DB
Replication
Bypass RLS
system superuser
replicator Replication pg_monitor
dbrole_readonly
system replicator
dbuser_monitor 16 connections pg_monitor
dbrole_readonly
system monitor user
dbuser_admin Bypass RLS dbrole_admin system admin user

相关配置

以下是8个默认用户/角色的相关变量

# - system roles - #
pg_replication_username: replicator           # system replication user
pg_replication_password: DBUser.Replicator    # system replication password
pg_monitor_username: dbuser_monitor           # system monitor user
pg_monitor_password: DBUser.Monitor           # system monitor password
pg_admin_username: dbuser_admin               # system admin user
pg_admin_password: DBUser.Admin               # system admin password

# - default roles - #
# chekc http://pigsty.cc/zh/docs/concepts/provision/acl/ for more detail
pg_default_roles:

  # common production readonly user
  - name: dbrole_readonly                 # production read-only roles
    login: false
    comment: role for global readonly access

  # common production read-write user
  - name: dbrole_readwrite                # production read-write roles
    login: false
    roles: [dbrole_readonly]             # read-write includes read-only access
    comment: role for global read-write access

  # offline have same privileges as readonly, but with limited hba access on offline instance only
  # for the purpose of running slow queries, interactive queries and perform ETL tasks
  - name: dbrole_offline
    login: false
    comment: role for restricted read-only access (offline instance)

  # admin have the privileges to issue DDL changes
  - name: dbrole_admin
    login: false
    bypassrls: true
    comment: role for object creation
    roles: [dbrole_readwrite,pg_monitor,pg_signal_backend]

  # dbsu, name is designated by `pg_dbsu`. It's not recommend to set password for dbsu
  - name: postgres
    superuser: true
    comment: system superuser

  # default replication user, name is designated by `pg_replication_username`, and password is set by `pg_replication_password`
  - name: replicator
    replication: true
    roles: [pg_monitor, dbrole_readonly]
    comment: system replicator

  # default replication user, name is designated by `pg_monitor_username`, and password is set by `pg_monitor_password`
  - name: dbuser_monitor
    connlimit: 16
    comment: system monitor user
    roles: [pg_monitor, dbrole_readonly]

  # default admin user, name is designated by `pg_admin_username`, and password is set by `pg_admin_password`
  - name: dbuser_admin
    bypassrls: true
    comment: system admin user
    roles: [dbrole_admin]

  # default stats user, for ETL and slow queries
  - name: dbuser_stats
    password: DBUser.Stats
    comment: business offline user for offline queries and ETL
    roles: [dbrole_offline]

默认用户有专用的用户名与密码配置选项,会覆盖pg_default_roles中的选项。因此无需在pg_default_roles中为默认用户配置密码。

出于安全考虑,不建议为DBSU配置密码,故pg_dbsu没有专门的密码配置项。如有需要,用户可以在pg_default_roles中为超级用户指定密码。

Pgbouncer用户

Pgbouncer的操作系统用户将与数据库超级用户保持一致,默认都使用postgres

Pigsty默认会使用Postgres管理用户作为Pgbouncer的管理用户,使用Postgres的监控用户同时作为Pgbouncer的监控用户。

Pgbouncer的用户权限通过/etc/pgbouncer/pgb_hba.conf进行控制。

Pgbounce的用户列表通过/etc/pgbouncer/userlist.txt文件进行控制。

定义用户时,只有显式添加pgbouncer: true 的用户,才会被加入到Pgbouncer的用户列表中。

用户的定义

Pigsty中的用户可以通过以下两个参数进行声明,两者使用同样的形式:

用户的创建

Pigsty的用户可以通过 pgsql-createuser.yml 剧本完成创建

权限模型

默认情况下,角色拥有的权限如下所示

GRANT USAGE                         ON SCHEMAS   TO dbrole_readonly
GRANT SELECT                        ON TABLES    TO dbrole_readonly
GRANT SELECT                        ON SEQUENCES TO dbrole_readonly
GRANT EXECUTE                       ON FUNCTIONS TO dbrole_readonly
GRANT USAGE                         ON SCHEMAS   TO dbrole_offline
GRANT SELECT                        ON TABLES    TO dbrole_offline
GRANT SELECT                        ON SEQUENCES TO dbrole_offline
GRANT EXECUTE                       ON FUNCTIONS TO dbrole_readonly
GRANT INSERT, UPDATE, DELETE        ON TABLES    TO dbrole_readwrite
GRANT USAGE,  UPDATE                ON SEQUENCES TO dbrole_readwrite
GRANT TRUNCATE, REFERENCES, TRIGGER ON TABLES    TO dbrole_admin
GRANT CREATE                        ON SCHEMAS   TO dbrole_admin
GRANT USAGE                         ON TYPES     TO dbrole_admin

其他业务用户默认都应当属于四种默认角色之一:只读读写管理员离线访问

所有用户都可以访问所有模式,只读用户可以读取所有表,读写用户可以对所有表进行DML操作,管理员可以执行DDL变更操作。离线用户与只读用户类似,但只允许访问pg_role == 'offline' 或带有 pg_offline_query = true 的实例。

数据库权限

数据库有三种权限:CONNECT, CREATE, TEMP,以及特殊的属主OWNERSHIP。数据库的定义由参数 pg_database 控制。一个完整的数据库定义如下所示:

pg_databases:
  - name: meta                      # name is the only required field for a database
    owner: postgres                 # optional, database owner
    template: template1             # optional, template1 by default
    encoding: UTF8                  # optional, UTF8 by default
    locale: C                       # optional, C by default
    allowconn: true                 # optional, true by default, false disable connect at all
    revokeconn: false               # optional, false by default, true revoke connect from public # (only default user and owner have connect privilege on database)
    tablespace: pg_default          # optional, 'pg_default' is the default tablespace
    connlimit: -1                   # optional, connection limit, -1 or none disable limit (default)
    extensions:                     # optional, extension name and where to create
      - {name: postgis, schema: public}
    parameters:                     # optional, extra parameters with ALTER DATABASE
      enable_partitionwise_join: true
    pgbouncer: true                 # optional, add this database to pgbouncer list? true by default
    comment: pigsty meta database   # optional, comment string for database

默认情况下,如果数据库没有配置属主,那么数据库超级用户dbsu将会作为数据库的默认OWNER,否则将为指定用户。

默认情况下,所有用户都具有对新创建数据库的CONNECT 权限,如果希望回收该权限,设置 revokeconn == true,则该权限会被回收。只有默认用户(dbsu|admin|monitor|replicator)与数据库的属主才会被显式赋予CONNECT权限。同时,admin|owner将会具有CONNECT权限的GRANT OPTION,可以将CONNECT权限转授他人。

如果希望实现不同数据库之间的访问隔离,可以为每一个数据库创建一个相应的业务用户作为owner,并全部设置revokeconn选项。这种配置对于多租户实例尤为实用。

创建新对象

默认情况下,出于安全考虑,Pigsty会撤销PUBLIC用户在数据库下CREATE新模式的权限,同时也会撤销PUBLIC用户在public模式下创建新关系的权限。数据库超级用户与管理员不受此限制,他们总是可以在任何地方执行DDL变更。

Pigsty非常不建议使用业务用户执行DDL变更,因为PostgreSQL的ALTER DEFAULT PRIVILEGE仅针对“由特定用户创建的对象”生效,默认情况下超级用户postgresdbuser_admin创建的对象拥有默认的权限配置,如果用户希望授予业务用户dbrole_admin,请在使用该业务管理员执行DDL变更时首先执行:

SET ROLE dbrole_admin; -- dbrole_admin 创建的对象具有正确的默认权限

在数据库中创建对象的权限与用户是否为数据库属主无关,这只取决于创建该用户时是否为该用户赋予管理员权限。

pg_users:
  - {name: test1, password: xxx , groups: [dbrole_readwrite]}  # 不能创建Schema与对象
  - {name: test2, password: xxx , groups: [dbrole_admin]}      # 可以创建Schema与对象

认证模型

HBA是Host Based Authentication的缩写,可以将其视作IP黑白名单。

HBA配置方式

在Pigsty中,所有实例的HBA都由配置文件生成而来,最终生成的HBA规则取决于实例的角色(pg_role) Pigsty的HBA由下列变量控制:

  • pg_hba_rules: 环境统一的HBA规则
  • pg_hba_rules_extra: 特定于实例或集群的HBA规则
  • pgbouncer_hba_rules: 链接池使用的HBA规则
  • pgbouncer_hba_rules_extra: 特定于实例或集群的链接池HBA规则

每个变量都是由下列样式的规则组成的数组:

- title: allow intranet admin password access
  role: common
  rules:
    - host    all     +dbrole_admin               10.0.0.0/8          md5
    - host    all     +dbrole_admin               172.16.0.0/12       md5
    - host    all     +dbrole_admin               192.168.0.0/16      md5

基于角色的HBA

role = common的HBA规则组会安装到所有的实例上,而其他的取值,例如(role : primary)则只会安装至pg_role = primary的实例上。因此用户可以通过角色体系定义灵活的HBA规则。

作为一个特例role: offline 的HBA规则,除了会安装至pg_role == 'offline'的实例,也会安装至pg_offline_query == true的实例上。

默认配置

在默认配置下,主库与从库会使用以下的HBA规则:

  • 超级用户通过本地操作系统认证访问
  • 其他用户可以从本地用密码访问
  • 复制用户可以从局域网段通过密码访问
  • 监控用户可以通过本地访问
  • 所有人都可以在元节点上使用密码访问
  • 管理员可以从局域网通过密码访问
  • 所有人都可以从内网通过密码访问
  • 读写用户(生产业务账号)可以通过本地(链接池)访问 (部分访问控制转交链接池处理)
  • 在从库上:只读用户(个人)可以从本地(链接池)访问。 (意味主库上拒绝只读用户连接)
  • pg_role == 'offline' 或带有pg_offline_query == true的实例上,会添加允许dbrole_offline分组用户访问的HBA规则。
#==============================================================#
# Default HBA
#==============================================================#
# allow local su with ident"
local   all             postgres                               ident
local   replication     postgres                               ident

# allow local user password access
local   all             all                                    md5

# allow local/intranet replication with password
local   replication     replicator                              md5
host    replication     replicator         127.0.0.1/32         md5
host    all             replicator         10.0.0.0/8           md5
host    all             replicator         172.16.0.0/12        md5
host    all             replicator         192.168.0.0/16       md5
host    replication     replicator         10.0.0.0/8           md5
host    replication     replicator         172.16.0.0/12        md5
host    replication     replicator         192.168.0.0/16       md5

# allow local role monitor with password
local   all             dbuser_monitor                          md5
host    all             dbuser_monitor      127.0.0.1/32        md5

#==============================================================#
# replica HBA
#==============================================================#


#==============================================================#
# special HBA for instance marked with 'pg_offline_query = true'
#==============================================================#
#  allow offline query (ETL,SAGA,Interactive) on offline instance
host    all     +dbrole_offline               10.0.0.0/8        md5
host    all     +dbrole_offline               172.16.0.0/12     md5
host    all     +dbrole_offline               192.168.0.0/16    md5



#==============================================================#
# Common HBA
#==============================================================#
#  allow meta node password access
host    all     all                         10.10.10.10/32      md5

#  allow intranet admin password access
host    all     +dbrole_admin               10.0.0.0/8          md5
host    all     +dbrole_admin               172.16.0.0/12       md5
host    all     +dbrole_admin               192.168.0.0/16      md5

#  allow intranet password access
host    all             all                 10.0.0.0/8          md5
host    all             all                 172.16.0.0/12       md5
host    all             all                 192.168.0.0/16      md5

#  allow local read/write (local production user via pgbouncer)
local   all     +dbrole_readonly                                md5
host    all     +dbrole_readonly           127.0.0.1/32         md5



#==============================================================#
# Extra HBA
#==============================================================#
# add extra hba rules here




#==============================================================#
# Ad Hoc HBA
#==============================================================#
# manual maintained hba rules
最后修改 2021-03-01: update provision concept (e831662)