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Message-Id: <1404124096-21445-16-git-send-email-drysdale@google.com> Date: Mon, 30 Jun 2014 11:28:15 +0100 From: David Drysdale <drysdale@...gle.com> To: linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org> Cc: Alexander Viro <viro@...iv.linux.org.uk>, Meredydd Luff <meredydd@...atehouse.org>, Kees Cook <keescook@...omium.org>, James Morris <james.l.morris@...cle.com>, linux-api@...r.kernel.org, David Drysdale <drysdale@...gle.com> Subject: [PATCH 4/5] man-pages: cap_rights_limit.2: limit FD rights for Capsicum Signed-off-by: David Drysdale <drysdale@...gle.com> --- man2/cap_rights_limit.2 | 171 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 171 insertions(+) create mode 100644 man2/cap_rights_limit.2 diff --git a/man2/cap_rights_limit.2 b/man2/cap_rights_limit.2 new file mode 100644 index 000000000000..3484ee1076aa --- /dev/null +++ b/man2/cap_rights_limit.2 @@ -0,0 +1,171 @@ +.\" +.\" Copyright (c) 2008-2010 Robert N. M. Watson +.\" Copyright (c) 2012-2013 The FreeBSD Foundation +.\" Copyright (c) 2013-2014 Google, Inc. +.\" All rights reserved. +.\" +.\" %%%LICENSE_START(BSD_2_CLAUSE) +.\" 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 CAP_RIGHTS_LIMIT 2 2014-05-07 "Linux" "Linux Programmer's Manual" +.SH NAME +cap_rights_limit \- limit Capsicum capability rights +.SH SYNOPSIS +.nf +.B #include <sys/capsicum.h> +.sp +.BI "int cap_rights_limit(int " fd ", const struct cap_rights *" rights , +.BI " unsigned int " fcntls , +.BI " int " nioctls ", unsigned int *" ioctls ); +.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 () +system call. +Once Capsicum capability rights are reduced, operations on the file descriptor +.I fd +will be limited to those permitted by the remainder of the arguments. +.PP +The +.I rights +argument describes the primary rights for the file descriptor, and +should be prepared using +.BR cap_rights_init (3) +family of functions. The complete list of primary rights can be found in the +.BR rights (7) +manual page. +.PP +If a file descriptor is granted the +.B CAP_FCNTL +primary capability right, the list of allowed +.BR fcntl (2) +commands can be selectively reduced (but never expanded) with the +.I fcntls +argument. The following flags may be specified in the +.I fcntls +argument: +.TP +.B CAP_FCNTL_GETFL +Permit +.B F_GETFL +command. +.TP +.B CAP_FCNTL_SETFL +Permit +.B F_SETFL +command. +.TP +.B CAP_FCNTL_GETOWN +Permit +.B F_GETOWN +command. +.TP +.B CAP_FCNTL_SETOWN +Permit +.B F_SETOWN +command. +.PP +A value of +.B CAP_FCNTL_ALL +for the +.I fcntls +argument leaves the set of allowed +.BR fcntl (2) +commands unchanged. +.PP +If a file descriptor is granted the +.B CAP_IOCTL +capability right, the list of allowed +.BR ioctl (2) +commands can be selectively reduced (but never expanded) using the +.I nioctls +and +.I ioctls +arguments. +The +.I ioctls +argument is an array of +.BR ioctl (2) +command values and the +.I nioctls +argument specifies the number of elements in the array. +.PP +If the +.I nioctls +argument is -1 or 0, the +.I ioctls +argument is ignored, and either all +.BR ioctl (2) +operations or no +.BR ioctl (2) +operations (respectively) will be allowed. +.PP +Capsicum capability rights assigned to a file descriptor can be obtained with the +.BR cap_rights_get (2) +system call. +.SH RETURN VALUE +.BR cap_rights_limit () +returns zero on success. On error, -1 is returned and +.I errno +is set appropriately. +.SH ERRORS +.TP +.B EBADF +.I fd +isn't a valid open file descriptor. +.TP +.B EINVAL +An invalid set of rights has been requested in +.IR rights . +.TP +.B ENOMEM +Out of memory. +.TP +.B ENOTCAPABLE +The arguments contain capability rights not present for the given file descriptor (Capsicum +capability rights list can only be reduced, never expanded). +.SH VERSION +Capsicum support was added to the kernel in version 3.???. +.SH SEE ALSO +.BR cap_enter (2), +.BR cap_rights_get (2), +.BR cap_rights_init (3), +.BR capsicum (7), +.BR rights (7) -- 2.0.0.526.g5318336 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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