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990beb037d
The goal here is to make it so applications can take the rights one would
normally get by calling caph_limit_stream() on a descriptor and build on
them as needed.
The tentatively planned use-case is an application that takes a socket and
hooks it up to std{err,out,in} for a fork()d child. It may be feasible to
apply limitations to such descriptors as long as it's a superset of those
normally applied to stdio.
Reviewed by: markj, oshobo (prior version; sans manpage addition)
Differential Revision: https://reviews.freebsd.org/D22993
160 lines
4.3 KiB
Groff
160 lines
4.3 KiB
Groff
.\" Copyright (c) 2016 Mariusz Zaborski <oshogbo@FreeBSD.org>
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.\" All rights reserved.
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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 AUTHORS 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 AUTHORS 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 January 2, 2020
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.Dt CAPSICUM_HELPERS 3
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.Os
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.Sh NAME
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.Nm caph_limit_stream ,
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.Nm caph_limit_stdin ,
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.Nm caph_limit_stderr ,
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.Nm caph_limit_stdout ,
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.Nm caph_limit_stdio ,
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.Nm caph_stream_rights ,
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.Nm caph_cache_tzdata ,
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.Nm caph_cache_catpages ,
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.Nm caph_enter ,
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.Nm caph_enter_casper ,
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.Nm caph_rights_limit ,
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.Nm caph_ioctls_limit ,
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.Nm caph_fcntls_limit
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.Nd "set of the capsicum helpers, part of the libcapsicum"
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.Sh LIBRARY
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.Lb libcapsicum
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.Sh SYNOPSIS
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.In capsicum_helpers.h
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.Ft int
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.Fn caph_enter "void"
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.Ft int
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.Fn caph_enter_casper "void"
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.Ft int
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.Fn caph_rights_limit "int fd" "const cap_rights_t *rights"
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.Ft int
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.Fn caph_ioctls_limit "int fd" "const unsigned long *cmds" "size_t ncmds"
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.Ft int
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.Fn caph_fcntls_limit "int fd" "uint32_t fcntlrights"
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.Ft int
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.Fn caph_limit_stream "int fd" "int flags"
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.Ft int
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.Fn caph_limit_stdin "void"
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.Ft int
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.Fn caph_limit_stderr "void"
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.Ft int
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.Fn caph_limit_stdout "void"
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.Ft int
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.Fn caph_limit_stdio "void"
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.Ft void
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.Fn caph_stream_rights "cap_rights_t *" "int flags"
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.Ft void
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.Fn caph_cache_tzdata "void"
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.Ft void
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.Fn caph_cache_catpages "void"
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.Sh DESCRIPTION
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The
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.Nm caph_enter ,
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.Nm caph_rights_limit ,
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.Nm caph_ioctls_limit
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and
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.Nm caph_fcntls_limit
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are respectively equivalent to
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.Xr cap_enter 2 ,
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.Xr cap_rights_limit 2 ,
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.Xr cap_ioctls_limit 2
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and
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.Xr cap_fcntls_limit 2 ,
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it returns success when the kernel is built without support of the capability
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mode.
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.Pp
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The
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.Nm caph_enter_casper
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is equivalent to the
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.Nm caph_enter
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it returns success when the system is built without Casper support.
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.Pp
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The
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.Nm capsicum helpers
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are a set of a inline functions which simplify modifying programs to use
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Capsicum.
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The goal is to reduce duplicated code patterns.
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The
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.Nm capsicum helpers
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are part of
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.Nm libcapsicum
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but there is no need to link to the library.
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.Pp
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.Fn caph_limit_stream
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restricts capabilities on
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.Fa fd
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to only those needed by POSIX stream objects (that is, FILEs).
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.Pp
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These flags can be provided:
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.Pp
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.Bl -tag -width "CAPH_IGNORE_EBADF" -compact -offset indent
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.It Dv CAPH_IGNORE_EBADF
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Do not return an error if file descriptor is invalid.
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.It Dv CAPH_READ
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Set CAP_READ on limited descriptor.
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.It Dv CAPH_WRITE
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Set CAP_WRITE on limited descriptor.
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.El
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.Pp
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.Fn caph_limit_stdin ,
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.Fn caph_limit_stderr
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and
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.Fn caph_limit_stdout
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limit standard descriptors using the
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.Nm caph_limit_stream
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function.
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.Pp
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.Fn caph_limit_stdio
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limits stdin, stderr and stdout.
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.Pp
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.Nm caph_stream_rights
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may be used to initialize
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.Fa rights
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with the same rights that a stream would be limited to, as if
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.Fn caph_limit_stream
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had been invoked using the same
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.Fa flags .
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.Pp
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.Fn caph_cache_tzdata
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precaches all timezone data needed to use
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.Li libc
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local time functions.
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.Pp
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.Fn caph_cache_catpages
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caches Native Language Support (NLS) data.
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NLS data is used for localized error printing by
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.Xr strerror 3
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and
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.Xr err 3 ,
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among others.
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.Ed
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.Sh SEE ALSO
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.Xr cap_enter 2 ,
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.Xr cap_rights_limit 2 ,
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.Xr rights 4
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