620 lines
12 KiB
Groff
620 lines
12 KiB
Groff
.\"
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.\" Copyright (c) 2008-2010 Robert N. M. Watson
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.\" Copyright (c) 2012-2013 The FreeBSD Foundation
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.\" All rights reserved.
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.\"
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.\" This software was developed at the University of Cambridge Computer
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.\" Laboratory with support from a grant from Google, Inc.
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.\"
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.\" Portions of this documentation were written by Pawel Jakub Dawidek
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.\" under sponsorship from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 23, 2013
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.Dt CAP_RIGHTS_LIMIT 2
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.Os
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.Sh NAME
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.Nm cap_rights_limit ,
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.Nm cap_rights_get
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.Nd manage capability rights
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/capability.h
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.Ft int
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.Fn cap_rights_limit "int fd" "cap_rights_t rights"
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.Ft int
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.Fn cap_rights_get "int fd" "cap_rights_t *rightsp"
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.Sh DESCRIPTION
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When a file descriptor is created by a function such as
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.Xr fhopen 2 ,
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.Xr kqueue 2 ,
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.Xr mq_open 2 ,
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.Xr open 2 ,
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.Xr openat 2 ,
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.Xr pdfork 2 ,
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.Xr pipe 2 ,
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.Xr shm_open 2 ,
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.Xr socket 2 ,
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or
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.Xr socketpair 2 ,
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it is assigned all capability rights.
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Those rights can be reduced (but never expanded) by using the
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.Fn cap_rights_limit
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system call.
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Once capability rights are reduced, operations on the file descriptor will be
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limited to those permitted by
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.Fa rights .
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.Pp
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A bitmask of capability rights assigned to a file descriptor can be obtained with
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the
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.Fn cap_rights_get
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system call.
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.Sh RIGHTS
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The following rights may be specified in a rights mask:
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.Bl -tag -width CAP_EXTATTR_DELETE
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.It Dv CAP_ACCEPT
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Permit
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.Xr accept 2
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and
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.Xr accept4 2 .
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.It Dv CAP_ACL_CHECK
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Permit checking of an ACL on a file descriptor; there is no cross-reference
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for this system call.
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.It Dv CAP_ACL_DELETE
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Permit
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.Xr acl_delete_fd_np 3 .
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.It Dv CAP_ACL_GET
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Permit
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.Xr acl_get_fd 3
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and
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.Xr acl_get_fd_np 3 .
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.It Dv CAP_ACL_SET
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Permit
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.Xr acl_set_fd 3
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and
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.Xr acl_set_fd_np 3 .
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.It Dv CAP_BIND
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Permit
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.Xr bind 2 .
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Note that sockets can also become bound implicitly as a result of
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.Xr connect 2
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or
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.Xr send 2 ,
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and that socket options set with
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.Xr setsockopt 2
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may also affect binding behavior.
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.It Dv CAP_BINDAT
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Permit
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.Xr bindat 2 .
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This right has to be present on the directory descriptor.
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.It Dv CAP_CONNECT
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Permit
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.Xr connect 2 ;
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also required for
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.Xr sendto 2
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with a non-NULL destination address.
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.It Dv CAP_CONNECTAT
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Permit
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.Xr connectat 2 .
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This right has to be present on the directory descriptor.
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.It Dv CAP_CREATE
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Permit
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.Xr openat 2
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with the
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.Dv O_CREAT
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flag.
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.\" XXXPJD: Doesn't exist anymore.
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.It Dv CAP_EVENT
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Permit
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.Xr select 2 ,
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.Xr poll 2 ,
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and
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.Xr kevent 2
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to be used in monitoring the file descriptor for events.
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.It Dv CAP_FEXECVE
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Permit
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.Xr fexecve 2
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and
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.Xr openat 2
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with the
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.Dv O_EXEC
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flag;
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.Dv CAP_READ
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will also be required.
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.It Dv CAP_EXTATTR_DELETE
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Permit
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.Xr extattr_delete_fd 2 .
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.It Dv CAP_EXTATTR_GET
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Permit
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.Xr extattr_get_fd 2 .
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.It Dv CAP_EXTATTR_LIST
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Permit
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.Xr extattr_list_fd 2 .
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.It Dv CAP_EXTATTR_SET
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Permit
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.Xr extattr_set_fd 2 .
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.It Dv CAP_FCHDIR
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Permit
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.Xr fchdir 2 .
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.It Dv CAP_FCHFLAGS
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Permit
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.Xr fchflags 2
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and
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.Xr chflagsat 2 .
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.It Dv CAP_CHFLAGSAT
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An alias to
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.Dv CAP_FCHFLAGS .
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.It Dv CAP_FCHMOD
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Permit
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.Xr fchmod 2
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and
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.Xr fchmodat 2 .
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.It Dv CAP_FCHMODAT
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An alias to
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.Dv CAP_FCHMOD .
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.It Dv CAP_FCHOWN
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Permit
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.Xr fchown 2
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and
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.Xr fchownat 2 .
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.It Dv CAP_FCHOWNAT
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An alias to
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.Dv CAP_FCHOWN .
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.It Dv CAP_FCNTL
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Permit
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.Xr fcntl 2 .
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Note that only the
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.Dv F_GETFL ,
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.Dv F_SETFL ,
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.Dv F_GETOWN
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and
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.Dv F_SETOWN
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commands require this capability right.
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Also note that the list of permitted commands can be further limited with the
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.Xr cap_fcntls_limit 2
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system call.
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.It Dv CAP_FLOCK
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Permit
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.Xr flock 2 ,
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.Xr fcntl 2
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(with
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.Dv F_GETLK ,
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.Dv F_SETLK
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or
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.Dv F_SETLKW
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flag) and
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.Xr openat 2
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(with
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.Dv O_EXLOCK
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or
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.Dv O_SHLOCK
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flag).
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.It Dv CAP_FPATHCONF
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Permit
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.Xr fpathconf 2 .
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.It Dv CAP_FSCK
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Permit UFS background-fsck operations on the descriptor.
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.It Dv CAP_FSTAT
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Permit
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.Xr fstat 2
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and
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.Xr fstatat 2 .
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.It Dv CAP_FSTATAT
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An alias to
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.Dv CAP_FSTAT .
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.It Dv CAP_FSTATFS
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Permit
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.Xr fstatfs 2 .
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.It Dv CAP_FSYNC
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Permit
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.Xr aio_fsync 2 ,
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.Xr fsync 2
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and
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.Xr openat 2
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with
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.Dv O_FSYNC
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or
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.Dv O_SYNC
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flag.
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.It Dv CAP_FTRUNCATE
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Permit
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.Xr ftruncate 2
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and
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.Xr openat 2
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with the
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.Dv O_TRUNC
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flag.
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.It Dv CAP_FUTIMES
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Permit
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.Xr futimes 2
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and
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.Xr futimesat 2 .
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.It Dv CAP_FUTIMESAT
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An alias to
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.Dv CAP_FUTIMES .
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.It Dv CAP_GETPEERNAME
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Permit
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.Xr getpeername 2 .
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.It Dv CAP_GETSOCKNAME
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Permit
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.Xr getsockname 2 .
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.It Dv CAP_GETSOCKOPT
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Permit
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.Xr getsockopt 2 .
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.It Dv CAP_IOCTL
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Permit
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.Xr ioctl 2 .
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Be aware that this system call has enormous scope, including potentially
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global scope for some objects.
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The list of permitted ioctl commands can be further limited with the
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.Xr cap_ioctls_limit 2
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system call.
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.\" XXXPJD: Doesn't exist anymore.
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.It Dv CAP_KEVENT
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Permit
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.Xr kevent 2 ;
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.Dv CAP_EVENT
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is also required on file descriptors that will be monitored using
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.Xr kevent 2 .
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.It Dv CAP_LINKAT
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Permit
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.Xr linkat 2
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and
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.Xr renameat 2 .
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This right is required for the destination directory descriptor.
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.It Dv CAP_LISTEN
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Permit
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.Xr listen 2 ;
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not much use (generally) without
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.Dv CAP_BIND .
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.It Dv CAP_LOOKUP
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Permit the file descriptor to be used as a starting directory for calls such as
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.Xr linkat 2 ,
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.Xr openat 2 ,
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and
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.Xr unlinkat 2 .
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.It Dv CAP_MAC_GET
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Permit
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.Xr mac_get_fd 3 .
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.It Dv CAP_MAC_SET
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Permit
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.Xr mac_set_fd 3 .
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.It Dv CAP_MKDIRAT
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Permit
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.Xr mkdirat 2 .
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.It Dv CAP_MKFIFOAT
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Permit
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.Xr mkfifoat 2 .
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.It Dv CAP_MKNODAT
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Permit
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.Xr mknodat 2 .
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.It Dv CAP_MMAP
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Permit
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.Xr mmap 2
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with the
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.Dv PROT_NONE
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protection.
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.It Dv CAP_MMAP_R
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Permit
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.Xr mmap 2
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with the
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.Dv PROT_READ
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protection.
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This also implies
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.Dv CAP_READ
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and
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.Dv CAP_SEEK
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rights.
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.It Dv CAP_MMAP_W
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Permit
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.Xr mmap 2
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with the
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.Dv PROT_WRITE
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protection.
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This also implies
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.Dv CAP_WRITE
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and
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.Dv CAP_SEEK
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rights.
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.It Dv CAP_MMAP_X
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Permit
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.Xr mmap 2
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with the
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.Dv PROT_EXEC
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protection.
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This also implies
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.Dv CAP_SEEK
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right.
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.It Dv CAP_MMAP_RW
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Implies
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.Dv CAP_MMAP_R
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and
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.Dv CAP_MMAP_W .
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.It Dv CAP_MMAP_RX
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Implies
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.Dv CAP_MMAP_R
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and
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.Dv CAP_MMAP_X .
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.It Dv CAP_MMAP_WX
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Implies
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.Dv CAP_MMAP_W
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and
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.Dv CAP_MMAP_X .
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.It Dv CAP_MMAP_RWX
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Implies
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.Dv CAP_MMAP_R ,
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.Dv CAP_MMAP_W
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and
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.Dv CAP_MMAP_X .
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.It Dv CAP_PDGETPID
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Permit
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.Xr pdgetpid 2 .
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.It Dv CAP_PDKILL
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Permit
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.Xr pdkill 2 .
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.It Dv CAP_PDWAIT
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Permit
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.Xr pdwait4 2 .
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.It Dv CAP_PEELOFF
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Permit
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.Xr sctp_peeloff 2 .
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.\" XXXPJD: Not documented.
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.It Dv CAP_POLL_EVENT
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.\" XXXPJD: Not documented.
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.It Dv CAP_POST_EVENT
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.It Dv CAP_PREAD
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Implies
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.Dv CAP_SEEK
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and
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.Dv CAP_READ .
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.It Dv CAP_PWRITE
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Implies
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.Dv CAP_SEEK
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and
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.Dv CAP_WRITE .
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.It Dv CAP_READ
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Allow
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.Xr aio_read 2 ,
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.Xr openat
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with the
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.Dv O_RDONLY flag,
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.Xr read 2 ,
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.Xr recv 2 ,
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.Xr recvfrom 2 ,
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.Xr recvmsg 2
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and related system calls.
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.It Dv CAP_RECV
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An alias to
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.Dv CAP_READ .
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.It Dv CAP_RENAMEAT
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Permit
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.Xr renameat 2 .
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This right is required for the source directory descriptor.
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.It Dv CAP_SEEK
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Permit operations that seek on the file descriptor, such as
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.Xr lseek 2 ,
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but also required for I/O system calls that can read or write at any position
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in the file, such as
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.Xr pread 2
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and
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.Xr pwrite 2 .
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.It Dv CAP_SEM_GETVALUE
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Permit
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.Xr sem_getvalue 3 .
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.It Dv CAP_SEM_POST
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Permit
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.Xr sem_post 3 .
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.It Dv CAP_SEM_WAIT
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Permit
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.Xr sem_wait 3
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and
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.Xr sem_trywait 3 .
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.It Dv CAP_SEND
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An alias to
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.Dv CAP_WRITE .
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.It Dv CAP_SETSOCKOPT
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Permit
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.Xr setsockopt 2 ;
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this controls various aspects of socket behavior and may affect binding,
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connecting, and other behaviors with global scope.
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.It Dv CAP_SHUTDOWN
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Permit explicit
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.Xr shutdown 2 ;
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closing the socket will also generally shut down any connections on it.
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.It Dv CAP_SYMLINKAT
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Permit
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.Xr symlinkat 2 .
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.It Dv CAP_TTYHOOK
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Allow configuration of TTY hooks, such as
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.Xr snp 4 ,
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on the file descriptor.
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.It Dv CAP_UNLINKAT
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Permit
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.Xr unlinkat 2
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and
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.Xr renameat 2 .
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This right is only required for
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.Xr renameat 2
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on the destination directory descriptor if the destination object already
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exists and will be removed by the rename.
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.It Dv CAP_WRITE
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Allow
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.Xr aio_write 2 ,
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.Xr openat 2
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with
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.Dv O_WRONLY
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and
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.Dv O_APPEND
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flags,
|
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.Xr send 2 ,
|
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.Xr sendmsg 2 ,
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.Xr sendto 2 ,
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.Xr write 2 ,
|
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and related system calls.
|
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For
|
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.Xr sendto 2
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with a non-NULL connection address,
|
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.Dv CAP_CONNECT
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is also required.
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For
|
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.Xr openat 2
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with the
|
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.Dv O_WRONLY
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flag, but without the
|
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.Dv O_APPEND
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flag,
|
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.Dv CAP_SEEK
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is also required.
|
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.El
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.Sh RETURN VALUES
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.Rv -std
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.Sh ERRORS
|
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.Fn cap_rights_limit
|
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succeeds unless:
|
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.Bl -tag -width Er
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.It Bq Er EBADF
|
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The
|
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.Fa fd
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argument is not a valid active descriptor.
|
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.It Bq Er EINVAL
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An invalid right has been requested in
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.Fa rights .
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.It Bq Er ENOTCAPABLE
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.Fa rights
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contains requested rights not present in the current rights mask associated
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with the given file descriptor.
|
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.El
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.Pp
|
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.Fn cap_rights_get
|
|
succeeds unless:
|
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.Bl -tag -width Er
|
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.It Bq Er EBADF
|
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The
|
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.Fa fd
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argument is not a valid active descriptor.
|
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.It Bq Er EFAULT
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The
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.Fa rightsp
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argument points at an invalid address.
|
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.El
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|
.Sh SEE ALSO
|
|
.Xr accept 2 ,
|
|
.Xr aio_fsync 2 ,
|
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.Xr aio_read 2 ,
|
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.Xr aio_write 2 ,
|
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.Xr bind 2 ,
|
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.Xr bindat 2 ,
|
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.Xr cap_enter 2 ,
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.Xr cap_fcntls_limit 2 ,
|
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.Xr cap_ioctls_limit 2 ,
|
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.Xr cap_rights_limit 2 ,
|
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.Xr connect 2 ,
|
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.Xr connectat 2 ,
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.Xr dup 2 ,
|
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.Xr dup2 2 ,
|
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.Xr extattr_delete_fd 2 ,
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.Xr extattr_get_fd 2 ,
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.Xr extattr_list_fd 2 ,
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.Xr extattr_set_fd 2 ,
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.Xr fchflags 2 ,
|
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.Xr fchown 2 ,
|
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.Xr fcntl 2 ,
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|
.Xr fexecve 2 ,
|
|
.Xr fhopen 2 ,
|
|
.Xr flock 2 ,
|
|
.Xr fpathconf 2 ,
|
|
.Xr fstat 2 ,
|
|
.Xr fstatfs 2 ,
|
|
.Xr fsync 2 ,
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|
.Xr ftruncate 2 ,
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|
.Xr futimes 2 ,
|
|
.Xr getpeername 2 ,
|
|
.Xr getsockname 2 ,
|
|
.Xr getsockopt 2 ,
|
|
.Xr ioctl 2 ,
|
|
.Xr kevent 2 ,
|
|
.Xr kqueue 2 ,
|
|
.Xr linkat 2 ,
|
|
.Xr listen 2 ,
|
|
.Xr mmap 2 ,
|
|
.Xr mq_open 2 ,
|
|
.Xr open 2 ,
|
|
.Xr openat 2 ,
|
|
.Xr pdfork 2 ,
|
|
.Xr pdgetpid 2 ,
|
|
.Xr pdkill 2 ,
|
|
.Xr pdwait4 2 ,
|
|
.Xr pipe 2 ,
|
|
.Xr poll 2 ,
|
|
.Xr pread 2 ,
|
|
.Xr pwrite 2 ,
|
|
.Xr read 2 ,
|
|
.Xr recv 2 ,
|
|
.Xr recvfrom 2 ,
|
|
.Xr recvmsg 2 ,
|
|
.Xr renameat 2 ,
|
|
.Xr sctp_peeloff 2 ,
|
|
.Xr select 2 ,
|
|
.Xr send 2 ,
|
|
.Xr sendmsg 2 ,
|
|
.Xr sendto 2 ,
|
|
.Xr setsockopt 2 ,
|
|
.Xr shm_open 2 ,
|
|
.Xr shutdown 2 ,
|
|
.Xr socket 2 ,
|
|
.Xr socketpair 2 ,
|
|
.Xr symlinkat 2 ,
|
|
.Xr unlinkat 2 ,
|
|
.Xr write 2 ,
|
|
.Xr acl_delete_fd_np 3 ,
|
|
.Xr acl_get_fd 3 ,
|
|
.Xr acl_get_fd_np 3 ,
|
|
.Xr acl_set_fd_np 3 ,
|
|
.Xr cap_limitfd 3 ,
|
|
.Xr libcapsicum 3 ,
|
|
.Xr mac_get_fd 3 ,
|
|
.Xr mac_set_fd 3 ,
|
|
.Xr sem_getvalue 3 ,
|
|
.Xr sem_post 3 ,
|
|
.Xr sem_trywait 3 ,
|
|
.Xr sem_wait 3 ,
|
|
.Xr capsicum 4 ,
|
|
.Xr snp 4
|
|
.Sh HISTORY
|
|
Support for capabilities and capabilities mode was developed as part of the
|
|
.Tn TrustedBSD
|
|
Project.
|
|
.Sh AUTHORS
|
|
This function was created by
|
|
.An Pawel Jakub Dawidek Aq pawel@dawidek.net
|
|
under sponsorship of the FreeBSD Foundation.
|
|
.Sh BUGS
|
|
This man page should list the set of permitted system calls more specifically
|
|
for each capability right.
|
|
.Pp
|
|
Capability rights sometimes have unclear indirect impacts, which should be
|
|
documented, or at least hinted at.
|