интерфейс маркировки SELinux пользовательского пространства и формат файла конфигурации для серверной части контекста объектов РСУБД (userspace SELinux labeling interface and configuration file format for the RDBMS objects context backend)
Имя (Name)
selabel_db - userspace SELinux labeling interface and
configuration file format for the RDBMS objects context backend
Синопсис (Synopsis)
#include <selinux/label.h>
int selabel_lookup(struct selabel_handle *hnd,
char **context,
const char *object_name, int object_type);
int selabel_lookup_raw(struct selabel_handle *hnd,
char **context,
const char *object_name, int object_type);
Описание (Description)
The DB contexts backend maps from a pair of object name and class
into security contexts. It is used to find the appropriate
context for database objects when relabeling a certain database.
The returned context must be freed using freecon(3).
selabel_lookup(3) describes the function with its return and
error codes.
The object_name should be a fully qualified name using the
hierarchy of database objects. For example, the pg_class table in
the postgres database and pg_catalog schema should be qualified
as:
Bpostgres.pg_catalog.pg_class
The NOTES section has further information on database support for
namespace hierarchies.
The object_type argument should be set to one of the following
values:
SELABEL_DB_DATABASE
The object_name argument specifies the name of a
database itself, such as "postgres".
SELABEL_DB_SCHEMA
The object_name argument specifies the name of a
schema object, such as "postgres.public".
SELABEL_DB_TABLE
The object_name argument specifies the name of a
table object, such as "postgres.public.my_table"
SELABEL_DB_COLUMN
The object_name argument specifies the name of a
column object, such as
"postgres.public.my_table.user_id"
SELABEL_DB_TUPLE
The object_name argument specifies the name of a
table object which contains the tuples to be
relabeled, such as "postgresql.public.my_table".
Note that we have no way to identify individual
tuple objects, except for WHERE clause on DML
statements, because it has no name.
SELABEL_DB_PROCEDURE
The object_name argument specifies the name of a
procedure object, such as
"postgres.public.my_func". Note that we don't
support lookup of individual security contexts for
procedures which have the same name but different
arguments.
SELABEL_DB_SEQUENCE
The object_name argument specifies the name of a
sequence object, such as "postgres.public.my_seq".
SELABEL_DB_BLOB
The object_name argument specifies the name of a
large object, such as "postgres.16308". Note that
a large object does not have a name, so it is
identified by its identifier value.
SELABEL_DB_VIEW
The object_name argument specifies the name of a
view object, such as "postgres.public.my_view".
SELABEL_DB_LANGUAGE
The object_name argument specifies the name of a
language object, such as "postgres.public.tcl".
SELABEL_DB_EXCEPTION
The object_name argument specifies the name of a
exception object.
SELABEL_DB_DATATYPE
The object_name argument specifies the name of a
type or domain object, such as
postgres.public.my_type.
Any messages generated by selabel_lookup(3) are sent to stderr by
default, although this can be changed by selinux_set_callback(3).
selabel_lookup_raw(3) behaves identically to selabel_lookup(3)
but does not perform context translation.
The FILES section details the configuration files used to
determine the database object context.
Параметры (Options)
In addition to the global options described in selabel_open(3),
this backend recognizes the following options:
SELABEL_OPT_PATH
A non-null value for this option specifies a path
to a file that will be opened in lieu of the
standard DB contexts file. It tries to open the
specfile designed for SE-PostgreSQL as default, so
if another RDBMS uses this interface, it needs to
give an explicit specfile designed for that RDBMS
(see the FILES section for details).
Файлы (Files)
The database context file used to retrieve a context depends on
the SELABEL_OPT_PATH parameter passed to selabel_open(3). If
NULL, then the SELABEL_OPT_PATH value will default to the active
policy database contexts location (as returned by
selinux_sepgsql_context_path(3)), otherwise the actual
SELABEL_OPT_PATH value specified is used (this option must be
used to support databases other than SE-PostgreSQL).
The default database object contexts file is:
/etc/selinux/{SELINUXTYPE}/contexts/sepgsql_context
Where {SELINUXTYPE} is the entry from the selinux configuration
file config (see selinux_config(5)).
The entries within the database contexts file are shown in the
Object Name String Values and FILE FORMAT sections.
Строковые значения имени объекта (Object name string values)
The string name assigned to each object_type argument that can be
present in the database contexts file are:
┌─────────────────────┬──────────────┐
│object_type │ Text Name │
├─────────────────────┼──────────────┤
│SELABEL_DB_DATABASE │ db_database │
├─────────────────────┼──────────────┤
│SELABEL_DB_SCHEMA │ db_schema │
├─────────────────────┼──────────────┤
│SELABEL_DB_VIEW │ db_view │
├─────────────────────┼──────────────┤
│SELABEL_DB_LANGUAGE │ db_language │
├─────────────────────┼──────────────┤
│SELABEL_DB_TABLE │ db_table │
├─────────────────────┼──────────────┤
│SELABEL_DB_COLUMN │ db_column │
├─────────────────────┼──────────────┤
│SELABEL_DB_TUPLE │ db_tuple │
├─────────────────────┼──────────────┤
│SELABEL_DB_PROCEDURE │ db_procedure │
├─────────────────────┼──────────────┤
│SELABEL_DB_SEQUENCE │ db_sequence │
├─────────────────────┼──────────────┤
│SELABEL_DB_BLOB │ db_blob │
├─────────────────────┼──────────────┤
│SELABEL_DB_EXCEPTION │ db_exception │
├─────────────────────┼──────────────┤
│SELABEL_DB_DATATYPE │ db_datatype │
└─────────────────────┴──────────────┘
Формат файла (File format)
Each line within the database contexts file is as follows:
object_type object_name context
Where:
object_type
This is the string representation of the object
type shown in the Object Name String Values
section.
object_name
The key used to obtain the context based on the
object_type.
The entry can contain '*' for wildcard matching or
'?' for substitution.
Note that if the '*' is used, then be aware that
the order of entries in the file is important. The
'*' on its own is used to ensure a default fallback
context is assigned and should be the last entry in
the object_type block.
context
The security context that will be applied to the
object.
The following example is for SE-PostgreSQL:
# ./contexts/sepgsql_contexts file
# object_type object_name context
db_database my_database system_u:object_r:sepgsql_db_t:s0
db_database * system_u:object_r:sepgsql_db_t:s0
db_schema *.*
system_u:object_r:sepgsql_schema_t:s0
db_tuple row_low system_u:object_r:sepgsql_table_t:s0
db_tuple row_high
system_u:object_r:sepgsql_table_t:s0:c1023
db_tuple *.*.* system_u:object_r:sepgsql_table_t:s0
Примечание (Note)
1. A suitable database contexts file needs to be written for the
target RDBMS and the SELABEL_OPT_PATH option must be used in
selabel_open(3) to load it.
2. The hierarchy of the namespace for database objects depends
on the RDBMS, however the selabel* interfaces do not have any
specific support for a namespace hierarchy.
SE-PostgreSQL has a namespace hierarchy where a database is
the top level object with the schema being the next level.
Under the schema object there can be other types of objects
such as tables and procedures. This hierarchy is supported as
follows:
If a security context is required for "my_table" table
in the "public" schema within the "postgres" database,
then the selabel_lookup(3) parameters for object_type
would be SELABEL_DB_TABLE and the object_name would be
"postgres.public.my_table", the security context (if
available), would be returned in context.
3. If contexts are to be validated, then the global option
SELABEL_OPT_VALIDATE must be set before calling
selabel_open(3). If this is not set, then it is possible for
an invalid context to be returned.
Смотри также (See also)
selinux(8), selabel_open(3), selabel_lookup(3), selabel_stats(3),
selabel_close(3), selinux_set_callback(3),
selinux_sepgsql_context_path(3), freecon(3), selinux_config(5)
