freebsd-dev/lib/libcapsicum/capsicum_helpers.3
Mariusz Zaborski 5a453d5f5b libcapsicum: Introduce caph_{rights,ioctls,fcntls}_limit
The idea behind those functions is not to force consumers to remember that there
is a need to check errno on failure. We already have a caph_enter(3) function
which does the same for cap_enter(2).

MFC after:	2 weeks
2018-11-04 17:22:58 +00:00

147 lines
3.9 KiB
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.\" Copyright (c) 2016 Mariusz Zaborski <oshogbo@FreeBSD.org>
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.Dd November 4, 2018
.Dt CAPSICUM_HELPERS 3
.Os
.Sh NAME
.Nm caph_limit_stream ,
.Nm caph_limit_stdin ,
.Nm caph_limit_stderr ,
.Nm caph_limit_stdout ,
.Nm caph_limit_stdio ,
.Nm caph_cache_tzdata ,
.Nm caph_cache_catpages ,
.Nm caph_enter ,
.Nm caph_enter_casper ,
.Nm caph_rights_limit ,
.Nm caph_ioctls_limit ,
.Nm caph_fcntls_limit
.Nd "set of the capsicum helpers, part of the libcapsicum"
.Sh LIBRARY
.Lb libcapsicum
.Sh SYNOPSIS
.In capsicum_helpers.h
.Ft int
.Fn caph_enter "void"
.Ft int
.Fn caph_enter_casper "void"
.Ft int
.Fn caph_rights_limit "inf fd" "const cap_righst_t *rights"
.Ft int
.Fn caph_ioctls_limit "inf fd" "const unsigned long *cmds" "size_t ncmds"
.Ft int
.Fn caph_fcntls_limit "inf fd" "uint32_t fcntlrights"
.Ft int
.Fn caph_limit_stdin "void"
.Ft int
.Fn caph_limit_stderr "void"
.Ft int
.Fn caph_limit_stdout "void"
.Ft int
.Fn caph_limit_stdio "void"
.Ft void
.Fn caph_cache_tzdata "void"
.Ft void
.Fn caph_cache_catpages "void"
.Sh DESCRIPTION
The
.Nm caph_enter ,
.Nm caph_rights_limit ,
.Nm caph_ioctls_limit
and
.Nm caph_fcntls_limit
are respectively equivalent to
.Xr cap_enter 2 ,
.Xr cap_rights_limit 2 ,
.Xr cap_ioctls_limit 2
and
.Xr cap_fcntls_limit 2 ,
it returns success when the kernel is built without support of the capability
mode.
.Pp
The
.Nm caph_enter_casper
is equivalent to the
.Nm caph_enter
it returns success when the system is built without Casper support.
.Pp
The
.Nm capsicum helpers
are a set of a inline functions which simplify modifying programs to use
Capsicum.
The goal is to reduce duplicated code patterns.
The
.Nm capsicum helpers
are part of
.Nm libcapsicum
but there is no need to link to the library.
.Pp
.Fn caph_limit_stream
restricts capabilities on
.Fa fd
to only those needed by POSIX stream objects (that is, FILEs).
.Pp
These flags can be provided:
.Pp
.Bl -tag -width "CAPH_IGNORE_EBADF" -compact -offset indent
.It Dv CAPH_IGNORE_EBADF
Do not return an error if file descriptor is invalid.
.It Dv CAPH_READ
Set CAP_READ on limited descriptor.
.It Dv CAPH_WRITE
Set CAP_WRITE on limited descriptor.
.El
.Pp
.Fn caph_limit_stdin ,
.Fn caph_limit_stderr
and
.Fn caph_limit_stdout
limit standard descriptors using the
.Nm caph_limit_stream
function.
.Pp
.Fn caph_limit_stdio
limits stdin, stderr and stdout.
.Pp
.Fn caph_cache_tzdata
precaches all timezone data needed to use
.Li libc
local time functions.
.Pp
.Fn caph_cache_catpages
caches Native Language Support (NLS) data.
NLS data is used for localized error printing by
.Xr strerror 3
and
.Xr err 3 ,
among others.
.Ed
.Sh SEE ALSO
.Xr cap_enter 2 ,
.Xr cap_rights_limit 2 ,
.Xr rights 4