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aeca4e2ca6
SafeSetID gates the setid family of syscalls to restrict UID/GID
transitions from a given UID/GID to only those approved by a
system-wide whitelist. These restrictions also prohibit the given
UIDs/GIDs from obtaining auxiliary privileges associated with
CAP_SET{U/G}ID, such as allowing a user to set up user namespace UID
mappings. For now, only gating the set*uid family of syscalls is
supported, with support for set*gid coming in a future patch set.
Signed-off-by: Micah Morton <mortonm@chromium.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.morris@microsoft.com>
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2.1 KiB
ReStructuredText
50 lines
2.1 KiB
ReStructuredText
===========================
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Linux Security Module Usage
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===========================
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The Linux Security Module (LSM) framework provides a mechanism for
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various security checks to be hooked by new kernel extensions. The name
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"module" is a bit of a misnomer since these extensions are not actually
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loadable kernel modules. Instead, they are selectable at build-time via
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CONFIG_DEFAULT_SECURITY and can be overridden at boot-time via the
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``"security=..."`` kernel command line argument, in the case where multiple
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LSMs were built into a given kernel.
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The primary users of the LSM interface are Mandatory Access Control
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(MAC) extensions which provide a comprehensive security policy. Examples
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include SELinux, Smack, Tomoyo, and AppArmor. In addition to the larger
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MAC extensions, other extensions can be built using the LSM to provide
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specific changes to system operation when these tweaks are not available
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in the core functionality of Linux itself.
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The Linux capabilities modules will always be included. This may be
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followed by any number of "minor" modules and at most one "major" module.
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For more details on capabilities, see ``capabilities(7)`` in the Linux
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man-pages project.
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A list of the active security modules can be found by reading
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``/sys/kernel/security/lsm``. This is a comma separated list, and
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will always include the capability module. The list reflects the
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order in which checks are made. The capability module will always
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be first, followed by any "minor" modules (e.g. Yama) and then
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the one "major" module (e.g. SELinux) if there is one configured.
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Process attributes associated with "major" security modules should
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be accessed and maintained using the special files in ``/proc/.../attr``.
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A security module may maintain a module specific subdirectory there,
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named after the module. ``/proc/.../attr/smack`` is provided by the Smack
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security module and contains all its special files. The files directly
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in ``/proc/.../attr`` remain as legacy interfaces for modules that provide
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subdirectories.
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.. toctree::
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:maxdepth: 1
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apparmor
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LoadPin
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SELinux
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Smack
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tomoyo
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Yama
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SafeSetID
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