cap_fcntls_limit(2) [freebsd man page]

CAP_FCNTLS_LIMIT(2)					      BSD System Calls Manual					       CAP_FCNTLS_LIMIT(2)

NAME

     cap_fcntls_limit, cap_fcntls_get -- manage allowed fcntl commands

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/capsicum.h>

     int
     cap_fcntls_limit(int fd, uint32_t fcntlrights);

     int
     cap_fcntls_get(int fd, uint32_t *fcntlrightsp);

DESCRIPTION

     If a file descriptor is granted the CAP_FCNTL capability right, the list of allowed fcntl(2) commands can be selectively reduced (but never
     expanded) with the cap_fcntls_limit() system call.

     A bitmask of allowed fcntls commands for a given file descriptor can be obtained with the cap_fcntls_get() system call.

FLAGS

     The following flags may be specified in the fcntlrights argument or returned in the fcntlrightsp argument:

     CAP_FCNTL_GETFL   Permit F_GETFL command.

     CAP_FCNTL_SETFL   Permit F_SETFL command.

     CAP_FCNTL_GETOWN  Permit F_GETOWN command.

     CAP_FCNTL_SETOWN  Permit F_SETOWN command.

RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the
     error.

ERRORS

     cap_fcntls_limit() succeeds unless:

     [EBADF]		The fd argument is not a valid descriptor.

     [EINVAL]		An invalid flag has been passed in fcntlrights.

     [ENOTCAPABLE]	fcntlrights would expand the list of allowed fcntl(2) commands.

     cap_fcntls_get() succeeds unless:

     [EBADF]		The fd argument is not a valid descriptor.

     [EFAULT]		The fcntlrightsp argument points at an invalid address.

SEE ALSO

     cap_ioctls_limit(2), cap_rights_limit(2), fcntl(2)

HISTORY

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

AUTHORS

     This function was created by Pawel Jakub Dawidek <pawel@dawidek.net> under sponsorship of the FreeBSD Foundation.

BSD
								  March 27, 2014							       BSD

CAP_ENTER(2)						      BSD System Calls Manual						      CAP_ENTER(2)

NAME

     cap_enter, cap_getmode -- Capability mode system calls

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <sys/capsicum.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 created with fork(2) or
     pdfork(2) will be placed in capability mode from inception.

     When combined with cap_rights_limit(2), cap_ioctls_limit(2), cap_fcntls_limit(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.  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 successful; otherwise the value -1 is returned and the global variable
     errno is set to indicate the error.

ERRORS

     The cap_enter() and cap_getmode() system calls will fail if:

     [ENOSYS]		The kernel is compiled without:

			options CAPABILITY_MODE

     The cap_getmode() system call may also return the following error:

     [EFAULT]		Pointer modep points outside the process's allocated address space.

SEE ALSO

     cap_fcntls_limit(2), cap_ioctls_limit(2), cap_rights_limit(2), fexecve(2), cap_sandboxed(3), 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 sup-
     port from a grant from Google, Inc.

BSD
								  March 27, 2014							       BSD