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CAPSICUM(4)	       FreeBSD Kernel Interfaces Manual		   CAPSICUM(4)

     Capsicum -- lightweight OS	capability and sandbox framework

     options CAPABILITY_MODE
     options CAPABILITIES

     Capsicum is a lightweight OS capability and sandbox framework implement-
     ing a hybrid capability system model.  Capsicum can be used for applica-
     tion 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	vulnerabilities.

     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 names-
	     paces) is restricted; only	explicitly delegated rights, refer-
	     enced 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 capabil-
	     ity 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 pro-
	     cesses 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).

     In	some cases, Capsicum limits the	valid values of	some parameters	to
     traditional APIs in order to restrict access to global namespaces:

     process IDs
	     Processes can only	act upon their own process ID with syscalls
	     such as cpuset_setaffinity(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),
     libcasper(3), procdesc(4)

     Capsicum first appeared in	FreeBSD	9.0, and was developed at the Univer-
     sity 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	11.1			 May 18, 2017			  FreeBSD 11.1


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