标签

PostgreSQL , 超级用户 , superuser

背景

在数据库中哪些操作需要超级用户的权限才能执行？

这个问题翻文档可能翻不全面，或者是已经比较难以完成的任务。

但是从源码里面是比较好找出这个答案的。

权限

例如

postgres=# select * from pg_authid;rolname      | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcanlogin | rolreplication | rolbypassrls | rolconnlimit | rolpassword | rolvaliduntil
-------------------+----------+------------+---------------+-------------+-------------+----------------+--------------+--------------+-------------+---------------postgres          | t        | t          | t             | t           | t           | t              | t            |           -1 |             | pg_signal_backend | f        | t          | f             | f           | f           | f              | f            |           -1 |             | test              | f        | t          | f             | f           | t           | f              | f            |           -1 |             | dba               | f        | t          | f             | f           | t           | f              | f            |           -1 |             | test1             | f        | t          | f             | f           | f           | f              | f            |           -1 |             | digoal            | f        | t          | f             | f           | t           | f              | f            |           -1 |             | a                 | f        | t          | f             | f           | t           | f              | f            |           -1 |             | b                 | f        | t          | f             | f           | t           | f              | f            |           -1 |             |
(8 rows)

rolsuper 就表示是否具备超级用户权限。

代码中如何判断超级用户

src/backend/utils/misc/superuser.c

/** The Postgres user running this command has Postgres superuser privileges*/
bool
superuser(void)
{return superuser_arg(GetUserId());
}/** The specified role has Postgres superuser privileges*/
bool
superuser_arg(Oid roleid)
{bool            result;HeapTuple       rtup;/* Quick out for cache hit */if (OidIsValid(last_roleid) && last_roleid == roleid)return last_roleid_is_super;/* Special escape path in case you deleted all your users. */if (!IsUnderPostmaster && roleid == BOOTSTRAP_SUPERUSERID)return true;/* OK, look up the information in pg_authid */rtup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));if (HeapTupleIsValid(rtup)){result = ((Form_pg_authid) GETSTRUCT(rtup))->rolsuper;  // 最终还是读取pg_authid中的rolsuper字段  ReleaseSysCache(rtup);}else{/* Report "not superuser" for invalid roleids */result = false;}/* If first time through, set up callback for cache flushes */if (!roleid_callback_registered){CacheRegisterSyscacheCallback(AUTHOID,RoleidCallback,(Datum) 0);roleid_callback_registered = true;}/* Cache the result for next time */last_roleid = roleid;last_roleid_is_super = result;return result;
}

在PostgreSQL代码里面，通过FormData_pg_authid结构来表示pg_authid的表结构

CATALOG(pg_authid,1260) BKI_SHARED_RELATION BKI_ROWTYPE_OID(2842) BKI_SCHEMA_MACRO
{NameData    rolname;        /* name of role */bool        rolsuper;       /* read this field via superuser() only! */bool        rolinherit;     /* inherit privileges from other roles? */bool        rolcreaterole;  /* allowed to create more roles? */bool        rolcreatedb;    /* allowed to create databases? */bool        rolcatupdate;   /* allowed to alter catalogs manually? */bool        rolcanlogin;    /* allowed to log in as session user? */bool        rolreplication; /* role used for streaming replication */int32       rolconnlimit;   /* max connections allowed (-1=no limit) *//* remaining fields may be null; use heap_getattr to read them! */text        rolpassword;    /* password, if any */timestamptz rolvaliduntil;  /* password expiration time, if any */
} FormData_pg_authid;#undef timestamptz/* ----------------*      Form_pg_authid corresponds to a pointer to a tuple with*      the format of pg_authid relation.* ----------------*/
typedef FormData_pg_authid *Form_pg_authid;

代码中如何判断用户是否有replication的权限

以此类推，

src/backend/utils/init/miscinit.c

/** Check whether specified role has explicit REPLICATION privilege*/
bool
has_rolreplication(Oid roleid)
{bool            result = false;HeapTuple       utup;utup = SearchSysCache1(AUTHOID, ObjectIdGetDatum(roleid));if (HeapTupleIsValid(utup)){result = ((Form_pg_authid) GETSTRUCT(utup))->rolreplication;ReleaseSysCache(utup);}return result;
}

人肉时间, 找出需要判断超级用户的地方

grep -r "superuser()" *contrib/file_fdw/file_fdw.c:    if (catalog == ForeignTableRelationId && !superuser())
contrib/dblink/dblink.c:        if (!superuser())
contrib/dblink/dblink.c:        if (!superuser())
contrib/pgstattuple/pgstatindex.c:      if (!superuser())
contrib/pgstattuple/pgstatindex.c:      if (!superuser())
contrib/pgstattuple/pgstatindex.c:      if (!superuser())
contrib/pgstattuple/pgstatindex.c:      if (!superuser())
contrib/pgstattuple/pgstatindex.c:      if (!superuser())
contrib/pgstattuple/pgstattuple.c:      if (!superuser())
contrib/pgstattuple/pgstattuple.c:      if (!superuser())
contrib/pgstattuple/pgstatapprox.c:     if (!superuser())
contrib/pg_stat_statements/pg_stat_statements.c:        bool            is_superuser = superuser();
contrib/sepgsql/label.c:        if (!superuser())
contrib/pageinspect/brinfuncs.c:        if (!superuser())
contrib/pageinspect/brinfuncs.c:        if (!superuser())
contrib/pageinspect/brinfuncs.c:        if (!superuser())
contrib/pageinspect/brinfuncs.c:        if (!superuser())
contrib/pageinspect/fsmfuncs.c: if (!superuser())
contrib/pageinspect/ginfuncs.c: if (!superuser())
contrib/pageinspect/ginfuncs.c: if (!superuser())
contrib/pageinspect/ginfuncs.c: if (!superuser())
contrib/pageinspect/heapfuncs.c:        if (!superuser())
contrib/pageinspect/heapfuncs.c:        if (!superuser())
contrib/pageinspect/btreefuncs.c:       if (!superuser())
contrib/pageinspect/btreefuncs.c:       if (!superuser())
contrib/pageinspect/btreefuncs.c:       if (!superuser())
contrib/pageinspect/rawpage.c:  if (!superuser())
contrib/pageinspect/rawpage.c:  if (!superuser())
contrib/adminpack/adminpack.c:  if (!superuser())
contrib/adminpack/adminpack.c:  if (!superuser())
contrib/postgres_fdw/connection.c:              if (!superuser() && !PQconnectionUsedPassword(conn))
contrib/postgres_fdw/connection.c:      if (superuser())
src/include/catalog/pg_authid.h:        bool            rolsuper;               /* read this field via superuser() only! */
src/test/modules/dummy_seclabel/dummy_seclabel.c:               if (!superuser())
src/test/regress/regress.c:     if (!superuser())
src/test/regress/regress.c:     if (!superuser())
src/backend/commands/copy.c:    if (!pipe && !superuser())
src/backend/commands/trigger.c:                 if (!superuser())
src/backend/commands/dbcommands.c:                (encoding == PG_SQL_ASCII && superuser())))
src/backend/commands/dbcommands.c:                (encoding == PG_SQL_ASCII && superuser())))
src/backend/commands/dbcommands.c:      if (superuser())
src/backend/commands/opclasscmds.c:     if (!superuser())
src/backend/commands/opclasscmds.c:     if (!superuser())
src/backend/commands/opclasscmds.c:     if (!superuser())
src/backend/commands/tablespace.c:      if (!superuser())
src/backend/commands/event_trigger.c:   if (!superuser())
src/backend/commands/foreigncmds.c:     if (!superuser())
src/backend/commands/foreigncmds.c:             if (!superuser())
src/backend/commands/foreigncmds.c:     if (!superuser())
src/backend/commands/foreigncmds.c:     if (!superuser())
src/backend/commands/tsearchcmds.c:     if (!superuser())
src/backend/commands/tsearchcmds.c:     if (!superuser())
src/backend/commands/amcmds.c:  if (!superuser())
src/backend/commands/amcmds.c:  if (!superuser())
src/backend/commands/functioncmds.c:            if (!superuser())
src/backend/commands/functioncmds.c:    if (isLeakProof && !superuser())
src/backend/commands/functioncmds.c:            if (procForm->proleakproof && !superuser())
src/backend/commands/functioncmds.c:            if (!superuser())
src/backend/commands/functioncmds.c:            if (!superuser())
src/backend/commands/tablecmds.c:                       if (!superuser())
src/backend/commands/extension.c:       if (control->superuser && !superuser())
src/backend/commands/aggregatecmds.c:           if (transTypeId == INTERNALOID && superuser())
src/backend/commands/aggregatecmds.c:                   if (mtransTypeId == INTERNALOID && superuser())
src/backend/commands/alter.c:   if (!superuser())
src/backend/commands/alter.c:   if (!superuser())
src/backend/commands/alter.c:           if (!superuser())
src/backend/commands/proclang.c:                if (!superuser())
src/backend/commands/proclang.c:                if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:                    if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:                    !superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/user.c:    if (grantorId != GetUserId() && !superuser())
src/backend/commands/user.c:            if (!superuser())
src/backend/commands/typecmds.c:        if (!superuser())
src/backend/commands/typecmds.c:                if (!superuser())
src/backend/libpq/be-fsstubs.c: if (!superuser())
src/backend/libpq/be-fsstubs.c: if (!superuser())
src/backend/catalog/system_views.sql:-- than use explicit 'superuser()' checks in those functions, we use the GRANT
src/backend/catalog/pg_proc.c:                                                          (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/tcop/utility.c:                             load_file(stmt->filename, !superuser());
src/backend/tcop/utility.c:                     if (!superuser())
src/backend/postmaster/pgstat.c:                        if (checkUser && !superuser() && beentry->st_userid != GetUserId())
src/backend/replication/slotfuncs.c:    if (!superuser() && !has_rolreplication(GetUserId()))
src/backend/replication/walreceiver.c:  if (!superuser())
src/backend/replication/walsender.c:            if (!superuser())
src/backend/replication/logical/origin.c:       if (!superuser())
src/backend/replication/logical/logicalfuncs.c: if (!superuser() && !has_rolreplication(GetUserId()))
src/backend/utils/fmgr/fmgr.c:                                          (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/utils/misc/guc.c:           !superuser())
src/backend/utils/misc/guc.c:   if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
src/backend/utils/misc/guc.c:   if (!superuser())
src/backend/utils/misc/guc.c:                                                                    (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/utils/misc/guc.c:                                                                    (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/utils/misc/guc.c:                                                    (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/utils/misc/guc.c:                                                    (superuser() ? PGC_SUSET : PGC_USERSET),
src/backend/utils/misc/guc.c:   bool            am_superuser = superuser();
src/backend/utils/misc/guc.c:   if ((record->flags & GUC_SUPERUSER_ONLY) && !superuser())
src/backend/utils/misc/guc.c:                   ((conf->flags & GUC_SUPERUSER_ONLY) && !superuser()))
src/backend/utils/misc/guc.c:   if (conf->source == PGC_S_FILE && superuser())
src/backend/utils/misc/guc.c:   if (superuser())
src/backend/utils/misc/guc.c:           if (superuser())
src/backend/utils/misc/guc.c:   else if (gconf->context == PGC_SUSET && superuser())
src/backend/utils/misc/guc.c:                                                    superuser() ? PGC_SUSET : PGC_USERSET,
src/backend/utils/misc/superuser.c: *     The superuser() function.  Determines if user has superuser privilege.
src/backend/utils/init/postinit.c:                      am_superuser = superuser();
src/backend/utils/init/postinit.c:              am_superuser = superuser();
src/backend/utils/init/postinit.c:              if (!superuser() && !has_rolreplication(GetUserId()))
src/backend/utils/adt/misc.c:   if (superuser_arg(proc->roleId) && !superuser())
src/backend/utils/adt/genfile.c:        if (!superuser())
src/backend/utils/adt/genfile.c:        if (!superuser())
src/backend/utils/adt/genfile.c:        if (!superuser())
src/backend/utils/adt/genfile.c:        if (!superuser())
src/bin/psql/prompt.c:                                  if (is_superuser())

去代码里面看吧，举一些例子

例子

1. 只有超级用户可以修改或设置file_fdw foreign table的options

contrib/file_fdw/file_fdw.cif (catalog == ForeignTableRelationId && !superuser())ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),errmsg("only superuser can change options of a file_fdw foreign table")));

2. 只有超级用户能读取数据库所在服务器的文件

src/backend/utils/adt/genfile.cDatum
pg_read_file(PG_FUNCTION_ARGS)
{
...if (!superuser())ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),(errmsg("must be superuser to read files"))));Datum
pg_read_binary_file(PG_FUNCTION_ARGS)
{
...if (!superuser())ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),(errmsg("must be superuser to read files"))));

3. 只有超级用户可以查看需要超级用户权限才能查看的参数

src/include/utils/guc.h/** bit values in "flags" of a GUC variable*/
#define GUC_LIST_INPUT                  0x0001  /* input can be list format */
#define GUC_LIST_QUOTE                  0x0002  /* double-quote list elements */
#define GUC_NO_SHOW_ALL                 0x0004  /* exclude from SHOW ALL */
#define GUC_NO_RESET_ALL                0x0008  /* exclude from RESET ALL */
#define GUC_REPORT                              0x0010  /* auto-report changes to client */
#define GUC_NOT_IN_SAMPLE               0x0020  /* not in postgresql.conf.sample */
#define GUC_DISALLOW_IN_FILE    0x0040  /* can't set in postgresql.conf */
#define GUC_CUSTOM_PLACEHOLDER  0x0080  /* placeholder for custom variable */
#define GUC_SUPERUSER_ONLY              0x0100  /* show only to superusers */
#define GUC_IS_NAME                             0x0200  /* limit string to NAMEDATALEN-1 */
#define GUC_NOT_WHILE_SEC_REST  0x0400  /* can't set if security restricted */
#define GUC_DISALLOW_IN_AUTO_FILE 0x0800                /* can't set insrc/backend/utils/misc/guc.cif (restrict_superuser &&(record->flags & GUC_SUPERUSER_ONLY) &&!superuser())ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),errmsg("must be superuser to examine \"%s\"", name)));
...

4. 只有超级用户能执行alter system

src/backend/utils/misc/guc.cif (!superuser())ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),(errmsg("must be superuser to execute ALTER SYSTEM command"))));

5. 只有超级用户能创建language

src/backend/commands/proclang.c/** Check permission*/if (!superuser()){if (!pltemplate->tmpldbacreate)ereport(ERROR,(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),errmsg("must be superuser to create procedural language \"%s\"",stmt->plname)));if (!pg_database_ownercheck(MyDatabaseId, GetUserId()))aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_DATABASE,get_database_name(MyDatabaseId));}

如果你发现报错中包含了权限错误的问题，也可以使用这个方法找到对应的代码。

\set VERBOSITY verbosetest=> \set VERBOSITY verbose
test=> create role b replication;
ERROR:  42501: must be superuser to create replication users
LOCATION:  CreateRole, user.c:319对应的代码在user.c的319行, CreateRole函数中.

就举这些例子，其他的可以自己看一下。

阿里云rds_superuser和superuser有什么区别

为了维护便利，阿里云RDS PostgreSQL开放了一个权限名为rds_superuser给用户，比superuser少一些权限，主要是文件操作相关的，并且不能越权做superuser能做的事情。

相比普通用户，rds_superuser多了以下权限(我们也会逐渐的开放更多的权限给用户，以下是目前支持的权限)。

-- 创建插件
create extension ?;  -- 创建非superuser,repliction权限用户
create role ?;  -- 非supuer owned对象的操作
alter table test.test rename to test1;
alter table test.test1 owner to test_rdssuper;
alter table test.test1 rename to test;
alter table test.test owner to test_norm;-- SET SESSION AUTHORIZATION、SET ROLE可以set非superuser用户
set role to test_norm;
reset role;-- 所有对象的vacuum、analyze操作
vacuum pg_class;
analyze pg_class;-- pg_stat_reset (pgstat_reset_counters) pg_stat_reset_shared（pgstat_reset_shared_counters）
select pg_stat_reset();
select pg_stat_reset_shared('bgwriter');-- pgstat_reset_single_counter
select pg_stat_reset_single_table_counters('test.test'::regclass::oid);
select pg_stat_reset_single_function_counters('pg_stat_get_activity'::regproc::oid);-- pg_stat_get_activity pg_stat_get_backend_activity pg_stat_get_backend_waiting pg_stat_get_backend_activity_start pg_stat_get_backend_xact_start pg_stat_get_backend_start pg_stat_get_backend_client_addr pg_stat_get_backend_client_port-- select pg_stat_get_activity()
SELECT pg_stat_get_backend_pid(s.backendid) AS pid, pg_stat_get_backend_activity(s.backendid) AS query,pg_stat_get_backend_waiting(s.backendid) AS waiting, pg_stat_get_backend_xact_start(s.backendid) AS xact_start, pg_stat_get_backend_start(s.backendid) AS bd_start, pg_stat_get_backend_client_addr(s.backendid) AS ip, pg_stat_get_backend_client_port(s.backendid) AS port FROM (SELECT pg_stat_get_backend_idset() AS backendid) AS s;-- pgstatindex pgstatindexbyid pgstatginindex pg_relpages pg_relpagesbyid pgstattuple
create extension pgstattuple;
SELECT * FROM pgstattuple('pg_catalog.pg_proc');
SELECT * FROM pgstatindex('pg_cast_oid_index');
SELECT * FROM pgstatginindex('test_gin_index'); -- pg_stat_statments-- 中文分词相关
CREATE EXTENSION zhparser;
CREATE TEXT SEARCH CONFIGURATION testzhcfg (PARSER = zhparser);
ALTER TEXT SEARCH CONFIGURATION testzhcfg ADD MAPPING FOR n,v,a,i,e,l WITH simple;-- finish prepared transaction，提交或回滚两阶段提交的事务
\c - test_norm
begin;
insert into test.test values(2);
prepare transaction 't1';
\c - test_rdssuper
select * from pg_prepared_xacts ;
commit prepared 't1';-- alter type owner
\c - test_norm
CREATE TYPE compfoo AS (f1 int, f2 text);
\c - test_rdssuper
alter type compfoo owner to test_rdssuper; -- 允许rds_superuser用户设置session_preload_libraries，以便于用户使用pg_hint_plan等
alter role all set session_preload_libraries = 'pg_hint_plan';
alter role all set set pg_hint_plan.debug_print = on;
\c - superuser
/*+ SeqScan(test.test) */ select * from test.test;
\c - test_rdssuper
/*+ SeqScan(test.test) */ select * from test.test;-- 支持设置session_preload_libraries，设置的值必须是rds_available_extensions里面的插件
alter role all set session_preload_libraries = 'plperlu';  -- ERROR: invalid value for parameter "session_preload_libraries": "plperlu"
alter role all set session_preload_libraries = 'plperl,postgis';-- grant role to
grant test_norm to test_rdssuper;-- revoke role from
revoke test_norm from test_rdssuper;-- rds_superuser可以set
SET SESSION AUTHORIZATION ?;-- 允许rds_superuser通过dblink连接本地数据库,不需要配置port,host,ip,只需要指定dbname-- 支持oss_fdw-- 创建RDS实例时的超级用户自带了replication角色，允许用来做流复制-- 允许rds_superuser设置temp_file_limit参数-- 允许rds_superuser修改schema
grant all on schema test to test_another;