Based on kernel version 3.9. Page generated on 2013-05-02 23:10 EST.
1 NetLabel Linux Security Module Interface 2 ============================================================================== 3 Paul Moore, email@example.com 4 5 May 17, 2006 6 7 * Overview 8 9 NetLabel is a mechanism which can set and retrieve security attributes from 10 network packets. It is intended to be used by LSM developers who want to make 11 use of a common code base for several different packet labeling protocols. 12 The NetLabel security module API is defined in 'include/net/netlabel.h' but a 13 brief overview is given below. 14 15 * NetLabel Security Attributes 16 17 Since NetLabel supports multiple different packet labeling protocols and LSMs 18 it uses the concept of security attributes to refer to the packet's security 19 labels. The NetLabel security attributes are defined by the 20 'netlbl_lsm_secattr' structure in the NetLabel header file. Internally the 21 NetLabel subsystem converts the security attributes to and from the correct 22 low-level packet label depending on the NetLabel build time and run time 23 configuration. It is up to the LSM developer to translate the NetLabel 24 security attributes into whatever security identifiers are in use for their 25 particular LSM. 26 27 * NetLabel LSM Protocol Operations 28 29 These are the functions which allow the LSM developer to manipulate the labels 30 on outgoing packets as well as read the labels on incoming packets. Functions 31 exist to operate both on sockets as well as the sk_buffs directly. These high 32 level functions are translated into low level protocol operations based on how 33 the administrator has configured the NetLabel subsystem. 34 35 * NetLabel Label Mapping Cache Operations 36 37 Depending on the exact configuration, translation between the network packet 38 label and the internal LSM security identifier can be time consuming. The 39 NetLabel label mapping cache is a caching mechanism which can be used to 40 sidestep much of this overhead once a mapping has been established. Once the 41 LSM has received a packet, used NetLabel to decode its security attributes, 42 and translated the security attributes into a LSM internal identifier the LSM 43 can use the NetLabel caching functions to associate the LSM internal 44 identifier with the network packet's label. This means that in the future 45 when a incoming packet matches a cached value not only are the internal 46 NetLabel translation mechanisms bypassed but the LSM translation mechanisms are 47 bypassed as well which should result in a significant reduction in overhead.