48 lines
2.4 KiB
Plaintext
48 lines
2.4 KiB
Plaintext
NetLabel Linux Security Module Interface
|
|
==============================================================================
|
|
Paul Moore, paul.moore@hp.com
|
|
|
|
May 17, 2006
|
|
|
|
* Overview
|
|
|
|
NetLabel is a mechanism which can set and retrieve security attributes from
|
|
network packets. It is intended to be used by LSM developers who want to make
|
|
use of a common code base for several different packet labeling protocols.
|
|
The NetLabel security module API is defined in 'include/net/netlabel.h' but a
|
|
brief overview is given below.
|
|
|
|
* NetLabel Security Attributes
|
|
|
|
Since NetLabel supports multiple different packet labeling protocols and LSMs
|
|
it uses the concept of security attributes to refer to the packet's security
|
|
labels. The NetLabel security attributes are defined by the
|
|
'netlbl_lsm_secattr' structure in the NetLabel header file. Internally the
|
|
NetLabel subsystem converts the security attributes to and from the correct
|
|
low-level packet label depending on the NetLabel build time and run time
|
|
configuration. It is up to the LSM developer to translate the NetLabel
|
|
security attributes into whatever security identifiers are in use for their
|
|
particular LSM.
|
|
|
|
* NetLabel LSM Protocol Operations
|
|
|
|
These are the functions which allow the LSM developer to manipulate the labels
|
|
on outgoing packets as well as read the labels on incoming packets. Functions
|
|
exist to operate both on sockets as well as the sk_buffs directly. These high
|
|
level functions are translated into low level protocol operations based on how
|
|
the administrator has configured the NetLabel subsystem.
|
|
|
|
* NetLabel Label Mapping Cache Operations
|
|
|
|
Depending on the exact configuration, translation between the network packet
|
|
label and the internal LSM security identifier can be time consuming. The
|
|
NetLabel label mapping cache is a caching mechanism which can be used to
|
|
sidestep much of this overhead once a mapping has been established. Once the
|
|
LSM has received a packet, used NetLabel to decode it's security attributes,
|
|
and translated the security attributes into a LSM internal identifier the LSM
|
|
can use the NetLabel caching functions to associate the LSM internal
|
|
identifier with the network packet's label. This means that in the future
|
|
when a incoming packet matches a cached value not only are the internal
|
|
NetLabel translation mechanisms bypassed but the LSM translation mechanisms are
|
|
bypassed as well which should result in a significant reduction in overhead.
|