[PATCH 3/6] rights.7: Describe Capsicum primary rights

[David Drysdale]

Signed-off-by: David Drysdale <drysdale@xxxxxxxxxx>
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+.\"
+.\" Copyright (c) 2014 Google, Inc.
+.\" Copyright (c) 2012-2013 The FreeBSD Foundation
+.\" Copyright (c) 2008-2010 Robert N. M. Watson
+.\" All rights reserved.
+.\"
+.\" This software was developed at the University of Cambridge Computer
+.\" Laboratory with support from a grant from Google, Inc.
+.\"
+.\" %%%LICENSE_START(BSD_2_CLAUSE)
+.\" Portions of this documentation were written by Pawel Jakub Dawidek
+.\" under sponsorship from the FreeBSD Foundation.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\" %%%LICENSE_END
+.\"
+.TH RIGHTS 7 2014-05-07 "Linux" "Linux Programmer's Manual"
+.SH NAME
+Capsicum capability rights for file descriptors
+.SH SYNOPSIS
+.B #include <linux/capsicum.h>
+.SH DESCRIPTION
+When a file descriptor is created by a function such as
+.BR accept (2),
+.BR accept4 (2),
+.BR creat (2),
+.BR epoll_create (2),
+.BR eventfd (2),
+.BR mq_open (2),
+.BR open (2),
+.BR openat (2),
+.BR pdfork (2),
+.BR pipe (2),
+.BR pipe2 (2),
+.BR signalfd (2),
+.BR socket (2),
+.BR socketpair (2)
+or
+.BR timerfd_create (2),
+it implicitly has all Capsicum capability rights.
+Those rights can be reduced (but never expanded) by using the
+.BR cap_rights_limit (2)
+system call.
+Once capability rights are reduced, operations on the file descriptor will be
+limited to those permitted by the associated rights.
+.Pp
+The list of primary capability rights is provided below. In addition,
+.BR ioctl (2)
+and
+.BR fcntl (2)
+can also be restricted to only allow specific commands.
+.PP
+The
+.I "struct cap_rights"
+type is used to store a list of primary capability rights; the
+.BR cap_rights_init (3)
+family of functions should be used to manage the structure.
+.SH RIGHTS
+The following rights may be specified in a rights mask:
+.TP
+.B CAP_ACCEPT
+Permit
+.BR accept (2)
+and
+.BR accept4 (2).
+.TP
+.B CAP_BIND
+Permit
+.BR bind (2).
+Note that sockets can also become bound implicitly as a result of
+.BR connect (2)
+or
+.BR send (2),
+and that socket options set with
+.BR setsockopt (2)
+may also affect binding behavior.
+.TP
+.B CAP_CONNECT
+Permit
+.BR connect (2);
+also required for
+.BR sendto (2)
+with a non-NULL destination address.
+.TP
+.B CAP_CREATE
+Permit
+.BR openat (2)
+with the
+.B O_CREAT
+flag.
+.TP
+.B CAP_EVENT
+Permit
+.BR select (2),
+.BR poll (2),
+and
+.BR epoll (7)
+to be used in monitoring the file descriptor for events.
+.TP
+.B CAP_EXTATTR_DELETE
+Permit
+.BR fremovexattr (2).
+.TP
+.B CAP_EXTATTR_GET
+Permit
+.BR fgetxattr (2).
+.TP
+.B CAP_EXTATTR_LIST
+Permit
+.BR flistxattr (2).
+.TP
+.B CAP_EXTATTR_SET
+Permit
+.BR fsetxattr (2).
+.TP
+.B CAP_FCHDIR
+Permit
+.BR fchdir (2).
+.TP
+.B CAP_FCHMOD
+Permit
+.BR fchmod (2)
+and
+.BR fchmodat (2)
+if the
+.B CAP_LOOKUP
+right is also present.
+.TP
+.B CAP_FCHMODAT
+An alias to
+.B CAP_FCHMOD
+and
+.BR CAP_LOOKUP .
+.TP
+.B CAP_FCHOWN
+Permit
+.BR fchown (2)
+and
+.BR fchownat (2)
+if the
+.B CAP_LOOKUP
+right is also present.
+.TP
+.B CAP_FCHOWNAT
+An alias to
+.B CAP_FCHOWN
+and
+.BR CAP_LOOKUP .
+.TP
+.B CAP_FCNTL
+Permit
+.BR fcntl (2).
+Note that only the
+.BR F_GETFL ,
+.BR F_SETFL ,
+.B F_GETOWN ,
+.B F_SETOWN ,
+.B F_GETOWN_EX
+and
+.B F_SETOWN_EX
+commands require this capability right.
+Also note that the list of permitted commands can be further limited with the
+.BR cap_rights_limit (2)
+system call.
+.TP
+.B CAP_FEXECVE
+Permit
+.BR execveat (2)
+and
+.BR openat (2)
+with the
+.B O_EXEC
+flag;
+.B CAP_READ
+is also required.
+.TP
+.B CAP_FLOCK
+Permit
+.BR flock (2)
+and
+.BR fcntl (2)
+(with
+.BR F_GETLK ,
+.BR F_SETLK
+or
+.B F_SETLKW
+flag).
+.TP
+.B CAP_FSTAT
+Permit
+.BR fstat (2).
+.TP
+.B CAP_FSTATFS
+Permit
+.BR fstatfs (2).
+.TP
+.B CAP_FSYNC
+Permit
+.BR fsync (2)
+and
+.BR openat (2)
+with the
+.B O_SYNC
+flag.
+.TP
+.B CAP_FTRUNCATE
+Permit
+.BR ftruncate (2)
+and
+.BR openat (2)
+with the
+.B O_TRUNC
+flag.
+.TP
+.B CAP_FUTIMES
+Permit
+.BR futimesat (2)
+if the
+.B CAP_LOOKUP
+right is also present.
+.TP
+.B CAP_FUTIMESAT
+An alias to
+.B CAP_FUTIMES
+and
+.BR CAP_LOOKUP .
+.TP
+.B CAP_GETPEERNAME
+Permit
+.BR getpeername (2).
+.TP
+.B CAP_GETSOCKNAME
+Permit
+.BR getsockname (2).
+.TP
+.B CAP_GETSOCKOPT
+Permit
+.BR getsockopt (2).
+.TP
+.B CAP_IOCTL
+Permit
+.BR ioctl (2).
+Be aware that this system call has enormous scope, including potentially
+global scope for some objects.
+The list of permitted ioctl commands can be further limited with the
+.BR cap_rights_limit (2)
+system call.
+.TP
+.B CAP_LINKAT
+Permit
+.BR linkat (2)
+and
+.BR renameat (2)
+on the destination directory descriptor.
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_LISTEN
+Permit
+.BR listen (2);
+not much use (generally) without
+.BR CAP_BIND .
+.TP
+.B CAP_LOOKUP
+Permit the file descriptor to be used as a starting directory for calls such as
+.BR linkat (2),
+.BR openat (2),
+and
+.BR unlinkat (2).
+.TP
+.B CAP_MKDIRAT
+Permit
+.BR mkdirat (2).
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_MKFIFOAT
+Permit
+.BR mkfifoat (2).
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_MKNODAT
+Permit
+.BR mknodat (2).
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_MMAP
+Permit
+.BR mmap (2)
+with the
+.B PROT_NONE
+protection.
+.TP
+.B CAP_MMAP_R
+Permit
+.BR mmap (2)
+with the
+.B PROT_READ
+protection.
+This right includes the
+.B CAP_READ
+and
+.B CAP_SEEK
+rights.
+.TP
+.B CAP_MMAP_RW
+An alias to
+.B CAP_MMAP_R
+and
+.BR CAP_MMAP_W .
+.TP
+.B CAP_MMAP_RWX
+An alias to
+.BR CAP_MMAP_R ,
+.B CAP_MMAP_W
+and
+.BR CAP_MMAP_X .
+.TP
+.B CAP_MMAP_RX
+An alias to
+.B CAP_MMAP_R
+and
+.BR CAP_MMAP_X .
+.TP
+.B CAP_MMAP_W
+Permit
+.BR mmap (2)
+with the
+.B PROT_WRITE
+protection.
+This right includes the
+.B CAP_WRITE
+and
+.B CAP_SEEK
+rights.
+.TP
+.B CAP_MMAP_WX
+An alias to
+.B CAP_MMAP_W
+and
+.BR CAP_MMAP_X .
+.TP
+.B CAP_MMAP_X
+Permit
+.BR mmap (2)
+with the
+.B PROT_EXEC
+protection.
+This right includes the
+.B CAP_SEEK
+right.
+.TP
+.B CAP_PDGETPID
+Permit
+.BR pdgetpid (2).
+.TP
+.B CAP_PDKILL
+Permit
+.BR pdkill (2).
+.TP
+.B CAP_PDWAIT
+Permit
+.BR pdwait4 (2).
+.TP
+.B CAP_PEELOFF
+Permit
+.BR sctp_peeloff (3).
+.TP
+.B CAP_PREAD
+An alias to
+.B CAP_READ
+and
+.BR CAP_SEEK .
+.TP
+.B CAP_PWRITE
+An alias to
+.B CAP_SEEK
+and
+.BR CAP_WRITE .
+.TP
+.B CAP_READ
+Permit
+.BR openat (2)
+with the
+.BR O_RDONLY flag,
+.BR read (2),
+.BR readv (2),
+.BR recv (2),
+.BR recvfrom (2),
+.BR recvmsg (2),
+.BR pread (2)
+(
+.B CAP_SEEK
+is also required),
+.BR preadv (2)
+(
+.B CAP_SEEK
+is also required) and related system calls.
+.TP
+.B CAP_RECV
+An alias to
+.BR CAP_READ .
+.TP
+.B CAP_RENAMEAT
+Permit
+.BR renameat (2).
+This right is required on the source directory descriptor.
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_SEEK
+Permit operations that seek on the file descriptor, such as
+.BR lseek (2),
+but also required for I/O system calls that can read or write at any position
+in the file, such as
+.BR pread (2)
+and
+.BR pwrite (2).
+.TP
+.B CAP_SEND
+An alias to
+.BR CAP_WRITE .
+.TP
+.B CAP_SETSOCKOPT
+Permit
+.BR setsockopt (2);
+this controls various aspects of socket behavior and may affect binding,
+connecting, and other behaviors with global scope.
+.TP
+.B CAP_SHUTDOWN
+Permit explicit
+.BR shutdown (2);
+closing the socket will also generally shut down any connections on it.
+.TP
+.B CAP_SYMLINKAT
+Permit
+.BR symlinkat (2).
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_UNLINKAT
+Permit
+.BR unlinkat (2)
+and
+.BR renameat (2).
+This right is only required for
+.BR renameat (2)
+on the destination directory descriptor if the destination object already
+exists and will be removed by the rename.
+This right includes the
+.B CAP_LOOKUP
+right.
+.TP
+.B CAP_WRITE
+Allow
+.BR openat (2)
+with
+.B O_WRONLY
+and
+.B O_APPEND
+flags set,
+.BR send (2),
+.BR sendmsg (2),
+.BR sendto (2),
+.BR write (2),
+.BR writev (2),
+.BR pwrite (2),
+.BR pwritev (2)
+and related system calls.
+For
+.BR sendto (2)
+with a non-NULL connection address,
+.B CAP_CONNECT
+is also required.
+For
+.BR openat (2)
+with the
+.B O_WRONLY
+flag, but without the
+.B O_APPEND
+flag,
+.B CAP_SEEK
+is also required.
+For
+.BR pwrite (2)
+and
+.BR pwritev (2)
+.B CAP_SEEK
+is also required.
+.SH VERSIONS
+Capsicum support was originally added to the kernel in version 3.???.
+.SH SEE ALSO
+.BR cap_enter (3),
+.BR cap_fcntls_limit (3),
+.BR cap_ioctls_limit (3),
+.BR cap_rights_limit (2),
+.BR cap_rights_limit (3),
+.BR capsicum (7)
--
2.0.0.526.g5318336

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