bionic (4) capsicum.4freebsd.gz

NAME

     Capsicum — lightweight OS capability and sandbox framework

SYNOPSIS

     options CAPABILITY_MODE
     options CAPABILITIES

DESCRIPTION

     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 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 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.

     capabilities
             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 namespaces:

     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).

     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).

SEE ALSO

     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)

HISTORY

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

AUTHORS

     Capsicum was developed by Robert Watson <rwatson@FreeBSD.org> and Jonathan Anderson <jonathan@FreeBSD.org>
     at the University of Cambridge, and Ben Laurie <benl@FreeBSD.org> and Kris Kennaway <kris@FreeBSD.org> at
     Google, Inc., and Pawel Jakub Dawidek <pawel@dawidek.net>.