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1 | Linux Security Module framework |
2 | ------------------------------- | |
3 | ||
4 | The Linux Security Module (LSM) framework provides a mechanism for | |
5 | various security checks to be hooked by new kernel extensions. The name | |
6 | "module" is a bit of a misnomer since these extensions are not actually | |
7 | loadable kernel modules. Instead, they are selectable at build-time via | |
8 | CONFIG_DEFAULT_SECURITY and can be overridden at boot-time via the | |
9 | "security=..." kernel command line argument, in the case where multiple | |
10 | LSMs were built into a given kernel. | |
11 | ||
12 | The primary users of the LSM interface are Mandatory Access Control | |
13 | (MAC) extensions which provide a comprehensive security policy. Examples | |
14 | include SELinux, Smack, Tomoyo, and AppArmor. In addition to the larger | |
15 | MAC extensions, other extensions can be built using the LSM to provide | |
16 | specific changes to system operation when these tweaks are not available | |
17 | in the core functionality of Linux itself. | |
18 | ||
19 | Without a specific LSM built into the kernel, the default LSM will be the | |
20 | Linux capabilities system. Most LSMs choose to extend the capabilities | |
21 | system, building their checks on top of the defined capability hooks. | |
22 | For more details on capabilities, see capabilities(7) in the Linux | |
23 | man-pages project. | |
24 | ||
591bcb18 | 25 | Based on https://lkml.org/lkml/2007/10/26/215, |
e163bc8e KC |
26 | a new LSM is accepted into the kernel when its intent (a description of |
27 | what it tries to protect against and in what cases one would expect to | |
28 | use it) has been appropriately documented in Documentation/security/. | |
29 | This allows an LSM's code to be easily compared to its goals, and so | |
30 | that end users and distros can make a more informed decision about which | |
31 | LSMs suit their requirements. | |
32 | ||
33 | For extensive documentation on the available LSM hook interfaces, please | |
34 | see include/linux/security.h. |