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.c
if (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.c
Datum
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 in
src/backend/utils/misc/guc.c
if (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.c
if (!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 verbose
test=> \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。
-- 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;
