Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
CAPSICUM(4)            FreeBSD Kernel Interfaces Manual            CAPSICUM(4)

     Capsicum - lightweight OS capability and sandbox framework

     options CAPABILITY_MODE
     options CAPABILITIES
     options PROCDESC

     Capsicum is a lightweight OS capability and sandbox framework
     implementing a hybrid capability system model.  Capsicum can be used for
     application and library compartmentalisation, the decomposition of larger
     bodies of software into isolated (sandboxed) components in order to
     implement security policies and limit the impact of software

     Capsicum provides two core kernel primitives:

     capability mode
             A process mode, entered by invoking cap_enter(2), in which access
             to global OS namespaces (such as the file system and PID
             namespaces) is restricted; only explicitly delegated rights,
             referenced by memory mappings or file descriptors, may be used.
             Once set, the flag is inherited by future children processes, and
             may not be cleared.

             Limit operations that can be called on file descriptors.  For
             example, a file descriptor returned by open(2) may be refined
             using cap_rights_limit(2) so that only read(2) and write(2) can
             be called, but not fchmod(2).  The complete list of the
             capability rights can be found in the rights(4) manual page.

     In some cases, Capsicum requires use of alternatives to traditional POSIX
     APIs in order to name objects using capabilities rather than global

     process descriptors
             File descriptors representing processes, allowing parent
             processes to manage child processes without requiring access to
             the PID namespace; described in greater detail in procdesc(4).

     anonymous shared memory
             An extension to the POSIX shared memory API to support anonymous
             swap objects associated with file descriptors; described in
             greater detail in shm_open(2).

     cap_enter(2), cap_fcntls_limit(2), cap_getmode(2), cap_ioctls_limit(2),
     cap_rights_limit(2), fchmod(2), open(2), pdfork(2), pdgetpid(2),
     pdkill(2), pdwait4(2), read(2), shm_open(2), write(2), cap_rights_get(3),

     Capsicum first appeared in FreeBSD 9.0, and was developed at the
     University of Cambridge.

     Capsicum was developed by Robert Watson <> and
     Jonathan Anderson <> at the University of Cambridge,
     and Ben Laurie <> and Kris Kennaway <> at
     Google, Inc., and Pawel Jakub Dawidek <>.

FreeBSD 11.0-PRERELEASE          July 25, 2015         FreeBSD 11.0-PRERELEASE


Want to link to this manual page? Use this URL:

home | help