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CAP_ENTER(2)		  FreeBSD System Calls Manual		  CAP_ENTER(2)

NAME
     cap_enter,	cap_getmode -- Capability mode system calls

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/capability.h>

     int
     cap_enter(void);

     int
     cap_getmode(u_int *modep);

DESCRIPTION
     cap_enter() places	the current process into capability mode, a mode of
     execution in which	processes may only issue system	calls operating	on
     file descriptors or reading limited global	system state.  Access to
     global name spaces, such as file system or	IPC name spaces, is prevented.
     If	the process is already in a capability mode sandbox, the system	call
     is	a no-op.  Future process descendants create with fork(2) or pdfork(2)
     will be placed in capability mode from inception.

     When combined with	capabilities created with cap_new(2), cap_enter() may
     be	used to	create kernel-enforced sandboxes in which appropriately-
     crafted applications or application components may	be run.

     cap_getmode() returns a flag indicating whether or	not the	process	is in
     a capability mode sandbox.

CAVEAT
     Creating effective	process	sandboxes is a tricky process that involves
     identifying the least possible rights required by the process and then
     passing those rights into the process in a	safe manner.  See the CAVEAT
     section of	cap_new(2) for why this	is particularly	tricky with UNIX file
     descriptors as the	canonical representation of a right.  Consumers	of
     cap_enter() should	also be	aware of other inherited rights, such as
     access to VM resources, memory contents, and other	process	properties
     that should be considered.	 It is advisable to use	fexecve(2) to create a
     runtime environment inside	the sandbox that has as	few implicitly
     acquired rights as	possible.

RETURN VALUES
     The cap_enter() and cap_getmode() functions return	the value 0 if suc-
     cessful; otherwise	the value -1 is	returned and the global	variable errno
     is	set to indicate	the error.

SEE ALSO
     cap_new(2), fexecve(2), capsicum(4)

HISTORY
     Support for capabilities and capabilities mode was	developed as part of
     the TrustedBSD Project.

AUTHORS
     These functions and the capability	facility were created by Robert	N. M.
     Watson at the University of Cambridge Computer Laboratory with support
     from a grant from Google, Inc.

FreeBSD	9.3		       February	25, 2012		   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | CAVEAT | RETURN VALUES | SEE ALSO | HISTORY | AUTHORS

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