如何从PostgreSQL源码分析哪些操作需要超级用户权限 - 阿里云rds superuser提供了哪些权限-阿里云开发者社区

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如何从PostgreSQL源码分析哪些操作需要超级用户权限 - 阿里云rds superuser提供了哪些权限

简介:

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(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;

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