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libcasper: Introduce cap_net a network service for Casper.

Browse Source 
Reviewed by:	emaste, markj (previous version), bcr (man page)
Differential Revision:	https://reviews.freebsd.org/D24688
This commit is contained in:
Mariusz Zaborski 2020-08-16 18:12:21 +00:00
parent f1780be99c
commit 832dc76b63
10 changed files with 3068 additions and 6 deletions
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1
lib/libcasper/services/Makefile
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@ -5,6 +5,7 @@
SUBDIR= cap_dns
SUBDIR+= cap_fileargs
SUBDIR+= cap_grp
SUBDIR+= cap_net
SUBDIR+= cap_pwd
SUBDIR+= cap_sysctl
SUBDIR+= cap_syslog

5
lib/libcasper/services/cap_dns/Makefile
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@ -27,11 +27,6 @@ SUBDIR.${MK_TESTS}+= tests
MAN+= cap_dns.3
MLINKS+=cap_dns.3 libcap_dns.3
MLINKS+=cap_dns.3 cap_gethostbyname.3
MLINKS+=cap_dns.3 cap_gethostbyname2.3
MLINKS+=cap_dns.3 cap_gethostbyaddr.3
MLINKS+=cap_dns.3 cap_getaddrinfo.3
MLINKS+=cap_dns.3 cap_getnameinfo.3
MLINKS+=cap_dns.3 cap_dns_type_limit.3
MLINKS+=cap_dns.3 cap_dns_family_limit.3

5
lib/libcasper/services/cap_dns/cap_dns.3
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@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd May 5, 2020
.Dd August 15, 2020
.Dt CAP_DNS 3
.Os
.Sh NAME
@ -58,6 +58,9 @@
.Fn cap_dns_family_limit "const cap_channel_t *chan" "const int *families" "size_t nfamilies"
.Sh DESCRIPTION
.Bf -symbolic
This service is obsolete and
.Xr cap_net 3
should be used instead.
The
.Fn cap_getaddrinfo ,
and

48
lib/libcasper/services/cap_net/Makefile Normal file
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@ -0,0 +1,48 @@
# $FreeBSD$
SHLIBDIR?= /lib/casper
.include <src.opts.mk>
PACKAGE=libcasper
SHLIB_MAJOR= 1
INCSDIR?= ${INCLUDEDIR}/casper
.if ${MK_CASPER} != "no"
SHLIB= cap_net
SRCS= cap_net.c
.endif
INCS= cap_net.h
LIBADD= nv
CFLAGS+=-I${.CURDIR}
CFLAGS+=-DWITH_CASPER
HAS_TESTS=
SUBDIR.${MK_TESTS}+= tests
MAN+= cap_net.3
MLINKS+=cap_net.3 libcap_net.3
MLINKS+=cap_net.3 cap_bind.3
MLINKS+=cap_net.3 cap_connect.3
MLINKS+=cap_net.3 cap_net_free.3
MLINKS+=cap_net.3 cap_net_limit.3
MLINKS+=cap_net.3 cap_net_limit_addr2name.3
MLINKS+=cap_net.3 cap_net_limit_addr2name_family.3
MLINKS+=cap_net.3 cap_net_limit_bind.3
MLINKS+=cap_net.3 cap_net_limit_connect.3
MLINKS+=cap_net.3 cap_net_limit_init.3
MLINKS+=cap_net.3 cap_net_limit_name2addr.3
MLINKS+=cap_net.3 cap_net_limit_name2addr_family.3
MLINKS+=cap_net.3 cap_getaddrinfo.3
MLINKS+=cap_net.3 cap_gethostbyaddr.3
MLINKS+=cap_net.3 cap_gethostbyname.3
MLINKS+=cap_net.3 cap_gethostbyname2.3
MLINKS+=cap_net.3 cap_getnameinfo.3
.include <bsd.lib.mk>

287
lib/libcasper/services/cap_net/cap_net.3 Normal file
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@ -0,0 +1,287 @@
.\" Copyright (c) 2020 Mariusz Zaborski <oshogbo@FreeBSD.org>
.\"
.\" 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 AUTHORS 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 AUTHORS 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.
.\"
.\" $FreeBSD$
.\"
.Dd August 15, 2020
.Dt CAP_NET 3
.Os
.Sh NAME
.Nm cap_bind ,
.Nm cap_connect ,
.Nm cap_getaddrinfo ,
.Nm cap_gethostbyaddr ,
.Nm cap_gethostbyname ,
.Nm cap_gethostbyname2 ,
.Nm cap_getnameinfo ,
.Nm cap_net_free ,
.Nm cap_net_limit ,
.Nm cap_net_limit_addr2name ,
.Nm cap_net_limit_addr2name_family ,
.Nm cap_net_limit_bind ,
.Nm cap_net_limit_connect ,
.Nm cap_net_limit_init ,
.Nm cap_net_limit_name2addr ,
.Nm cap_net_limit_name2addr_family ,
.Nd "library for networking in capability mode"
.Sh LIBRARY
.Lb libcap_net
.Sh SYNOPSIS
.In sys/nv.h
.In libcasper.h
.In casper/cap_net.h
.Ft int
.Fn cap_bind "cap_channel_t *chan" "int s" "const struct sockaddr *addr" "socklen_t addrlen"
.Ft int
.Fn cap_connect "cap_channel_t *chan" "int s" "const struct sockaddr *name" "socklen_t namelen"
.Ft int
.Fn cap_getaddrinfo "cap_channel_t *chan" "const char *hostname" "const char *servname" "const struct addrinfo *hints" "struct addrinfo **res"
.Ft int
.Fn cap_getnameinfo "cap_channel_t *chan" "const struct sockaddr *sa" "socklen_t salen" "char *host" "size_t hostlen" "char *serv" "size_t servlen" "int flags"
.Ft "struct hostent *"
.Fn cap_gethostbyname "const cap_channel_t *chan" "const char *name"
.Ft "struct hostent *"
.Fn cap_gethostbyname2 "const cap_channel_t *chan" "const char *name" "int af"
.Ft "struct hostent *"
.Fn cap_gethostbyaddr "const cap_channel_t *chan" "const void *addr" "socklen_t len" "int af"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_init "cap_channel_t *chan" "uint64_t mode"
.Ft int
.Fn cap_net_limit "cap_net_limit_t *limit"
.Ft void
.Fn cap_net_free "cap_net_limit_t *limit"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_addr2name_family "cap_net_limit_t *limit" "int *family" "size_t size"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_addr2name "cap_net_limit_t *limit" "const struct sockaddr *sa" "socklen_t salen"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_name2addr_family "cap_net_limit_t *limit" "int *family" "size_t size"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_name2addr "cap_net_limit_t *limit" "const char *name" "const char *serv"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_connect "cap_net_limit_t *limit" "const struct sockaddr *sa" "socklen_t salen"
.Ft "cap_net_limit_t *"
.Fn cap_net_limit_bind "cap_net_limit_t *limit" "const struct sockaddr *sa" "socklen_t salen"
.Sh DESCRIPTION
.Pp
The functions
.Fn cap_bind,
.Fn cap_connect,
.Fn cap_gethostbyname ,
.Fn cap_gethostbyname2 ,
.Fn cap_gethostbyaddr
and
.Fn cap_getnameinfo
are respectively equivalent to
.Xr bind 2 ,
.Xr connect 2 ,
.Xr gethostbyname 3 ,
.Xr gethostbyname2 3 ,
.Xr gethostbyaddr 3
and
.Xr getnameinfo 3
except that the connection to the
.Nm system.net
service needs to be provided.
.Sh LIMITS
By default, the cap_net capability provides unrestricted access to the network
namespace.
Applications typically only require access to a small portion of the network
namespace:
.Fn cap_net_limit
interface can be used to restrict access to the network.
.Fn cap_net_limit_init
returns an opaque limit handle used to store a list of capabilities.
The
.Fv mode
restricts the functionality of the service.
Modes are encoded using the following flags:
.Pp
.Bd -literal -offset indent -compact
CAPNET_ADDR2NAME reverse DNS lookups are allowed with
cap_getnameinfo
CAPNET_NAME2ADDR name resolution is allowed with
cap_getaddrinfo
CAPNET_DEPRECATED_ADDR2NAME reverse DNS lookups are allowed with
cap_gethostbyaddr
CAPNET_DEPRECATED_NAME2ADDR name resolution is allowed with
cap_gethostbyname and cap_gethostbyname2
CAPNET_BIND bind syscall is allowed
CAPNET_CONNECT connect syscall is allowed
CAPNET_CONNECTDNS connect syscall is allowed to the values
returned from privies call to
the cap_getaddrinfo or cap_gethostbyname
.Ed
.Pp
.Fn cap_net_limit_addr2name_family
limits the
.Fn cap_getnameinfo
and
.Fn cap_gethostbyaddr
to do reverse DNS lookups to specific family (AF_INET, AF_INET6, etc.)
.Pp
.Fn cap_net_limit_addr2name
limits the
.Fn cap_getnameinfo
and
.Fn cap_gethostbyaddr
to do reverse DNS lookups only on those specific structures.
.Pp
.Fn cap_net_limit_name2addr_family
limits the
.Fn cap_getaddrinfo ,
.Fn cap_gethostbyname
and
.Fn cap_gethostbyname2
to do the name resolution on specific family (AF_INET, AF_INET6, etc.)
.Pp
.Fn cap_net_limit_addr2name
restricts
.Fn cap_getaddrinfo ,
.Fn cap_gethostbyname
and
.Fn cap_gethostbyname2
to a set of domains.
.Pp
.Fn cap_net_limit_bind
limits
.Fn cap_bind
to bind only on those specific structures.
.Pp
.Fn cap_net_limit_connect
limits
.Fn cap_connect
to connect only on those specific structures.
If the CAPNET_CONNECTDNS is set the limits are extended to the values returned
by
.Fn cap_getaddrinfo ,
.Fn cap_gethostbyname
and
.Fn cap_gethostbyname2
In case of the
.Fn cap_getaddrinfo
the restriction is strict.
In case of the
.Fn cap_gethostbyname
and
.Fn cap_gethostbyname2
any port will be accepted in the
.Fn cap_connect
function.
.Pp
.Fn cap_net_limit
applies a set of sysctl limits to the capability, denying access to sysctl
variables not belonging to the set.
.Pp
Once a set of limits is applied, subsequent calls to
.Fn cap_net_limit
will fail unless the new set is a subset of the current set.
.Pp
The
.Fn cap_net_limit
will consume the limits.
If the
.Fn cap_net_limit
was not called the rights may be freed using
.Fn cap_net_free .
Multiple calls to
.Fn cap_net_limit_addr2name_family ,
.Fn cap_net_limit_addr2name ,
.Fn cap_net_limit_name2addr_family ,
.Fn cap_net_limit_name2addr ,
.Fn cap_net_limit_connect ,
and
.Fn cap_net_limit_bind
is supported, each call is extending preview capabilities.
.Sh EXAMPLES
The following example first opens a capability to casper and then uses this
capability to create the
.Nm system.net
casper service and uses it to resolve a host and connect to it.
.Bd -literal
cap_channel_t *capcas, *capnet;
cap_net_limit_t *limit;
int familylimit, error, s;
const char *host = "example.com";
struct addrinfo hints, *res;
/* Open capability to Casper. */
capcas = cap_init();
if (capcas == NULL)
err(1, "Unable to contact Casper");
/* Cache NLA for gai_strerror. */
caph_cache_catpages();
/* Enter capability mode sandbox. */
if (caph_enter_casper() < 0)
err(1, "Unable to enter capability mode");
/* Use Casper capability to create capability to the system.net service. */
capnet = cap_service_open(capcas, "system.net");
if (capnet == NULL)
err(1, "Unable to open system.net service");
/* Close Casper capability. */
cap_close(capcas);
/* Limit system.net to reserve IPv4 addresses, to host example.com . */
limit = cap_net_limit_init(capnet, CAPNET_NAME2ADDR | CAPNET_CONNECTDNS);
if (limit == NULL)
err(1, "Unable to create limits.");
cap_net_limit_name2addr(limit, host, "80");
familylimit = AF_INET;
cap_net_limit_name2addr_family(limit, &familylimit, 1);
if (cap_net_limit(limit) < 0)
err(1, "Unable to apply limits.");
/* Find IP addresses for the given host. */
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
error = cap_getaddrinfo(capnet, host, "80", &hints, &res);
if (error != 0)
errx(1, "cap_getaddrinfo(): %s: %s", host, gai_strerror(error));
s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
if (s < 0)
err(1, "Unable to create socket");
if (cap_connect(capnet, s, res->ai_addr, res->ai_addrlen) < 0)
err(1, "Unable to connect to host");
.Ed
.Sh SEE ALSO
.Xr bind 2 ,
.Xr cap_enter 2 ,
.Xr connect 2 ,
.Xr caph_enter 3 ,
.Xr err 3 ,
.Xr gethostbyaddr 3 ,
.Xr gethostbyname 3 ,
.Xr gethostbyname2 3 ,
.Xr getnameinfo 3 ,
.Xr capsicum 4 ,
.Xr nv 9
.Sh AUTHORS
.An Mariusz Zaborski Aq Mt oshogbo@FreeBSD.org

1385
lib/libcasper/services/cap_net/cap_net.c Normal file
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165
lib/libcasper/services/cap_net/cap_net.h Normal file
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@ -0,0 +1,165 @@
/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2020 Mariusz Zaborski <oshogbo@FreeBSD.org>
*
* 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 AUTHORS 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 AUTHORS 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.
*
* $FreeBSD$
*/
#ifndef _CAP_NETWORK_H_
#define _CAP_NETWORK_H_
#ifdef HAVE_CASPER
#define WITH_CASPER
#endif
#include <sys/dnv.h>
#include <sys/nv.h>
#include <sys/socket.h>
struct addrinfo;
struct hostent;
struct cap_net_limit;
typedef struct cap_net_limit cap_net_limit_t;
#define CAPNET_ADDR2NAME (0x01)
#define CAPNET_NAME2ADDR (0x02)
#define CAPNET_DEPRECATED_ADDR2NAME (0x04)
#define CAPNET_DEPRECATED_NAME2ADDR (0x08)
#define CAPNET_CONNECT (0x10)
#define CAPNET_BIND (0x20)
#define CAPNET_CONNECTDNS (0x40)
#ifdef WITH_CASPER
/* Capability functions. */
int cap_bind(cap_channel_t *chan, int s, const struct sockaddr *addr,
socklen_t addrlen);
int cap_connect(cap_channel_t *chan, int s, const struct sockaddr *name,
socklen_t namelen);
int cap_getaddrinfo(cap_channel_t *chan, const char *hostname,
const char *servname, const struct addrinfo *hints, struct addrinfo **res);
int cap_getnameinfo(cap_channel_t *chan, const struct sockaddr *sa,
socklen_t salen, char *host, size_t hostlen, char *serv, size_t servlen,
int flags);
/* Limit functions. */
cap_net_limit_t *cap_net_limit_init(cap_channel_t *chan, uint64_t mode);
int cap_net_limit(cap_net_limit_t *limit);
void cap_net_free(cap_net_limit_t *limit);
cap_net_limit_t *cap_net_limit_addr2name_family(cap_net_limit_t *limit,
int *family, size_t size);
cap_net_limit_t *cap_net_limit_addr2name(cap_net_limit_t *limit,
const struct sockaddr *sa, socklen_t salen);
cap_net_limit_t *cap_net_limit_name2addr_family(cap_net_limit_t *limit,
int *family, size_t size);
cap_net_limit_t *cap_net_limit_name2addr(cap_net_limit_t *limit,
const char *name, const char *serv);
cap_net_limit_t *cap_net_limit_connect(cap_net_limit_t *limit,
const struct sockaddr *sa, socklen_t salen);
cap_net_limit_t *cap_net_limit_bind(cap_net_limit_t *limit,
const struct sockaddr *sa, socklen_t salen);
/* Deprecated functions. */
struct hostent *cap_gethostbyname(cap_channel_t *chan, const char *name);
struct hostent *cap_gethostbyname2(cap_channel_t *chan, const char *name,
int af);
struct hostent *cap_gethostbyaddr(cap_channel_t *chan, const void *addr,
socklen_t len, int af);
#else
/* Capability functions. */
#define cap_bind(chan, s, addr, addrlen) \
bind(s, addr, addrlen)
#define cap_connect(chan, s, name, namelen) \
connect(s, name, namelen)
#define cap_getaddrinfo(chan, hostname, servname, hints, res) \
getaddrinfo(hostname, servname, hints, res)
#define cap_getnameinfo(chan, sa, salen, host, hostlen, serv, servlen, flags) \
getnameinfo(sa, salen, host, hostlen, serv, servlen, flags)
/* Limit functions. */
#define cap_net_limit_init(chan, mode) ((cap_net_limit_t *)malloc(8))
#define cap_net_free(limit) free(limit)
static inline int
cap_net_limit(cap_net_limit_t *limit)
{
free(limit);
return (0);
}
static inline cap_net_limit_t *
cap_net_limit_addr2name_family(cap_net_limit_t *limit,
int *family __unused, size_t size __unused)
{
return (limit);
}
static inline cap_net_limit_t *
cap_net_limit_addr2name(cap_net_limit_t *limit,
const struct sockaddr *sa __unused, socklen_t salen __unused)
{
return (limit);
}
static inline cap_net_limit_t *
cap_net_limit_name2addr_family(cap_net_limit_t *limit,
int *family __unused, size_t size __unused)
{
return (limit);
}
static inline cap_net_limit_t *
cap_net_limit_name2addr(cap_net_limit_t *limit,
const char *name __unused, const char *serv __unused)
{
return (limit);
}
static inline cap_net_limit_t *
cap_net_limit_connect(cap_net_limit_t *limit,
const struct sockaddr *sa __unused, socklen_t salen __unused)
{
return (limit);
}
static inline cap_net_limit_t *
cap_net_limit_bind(cap_net_limit_t *limit,
const struct sockaddr *sa __unused, socklen_t salen __unused)
{
return (limit);
}
/* Deprecated functions. */
#define cap_gethostbyname(chan, name) gethostbyname(name)
#define cap_gethostbyname2(chan, name, type) gethostbyname2(name, type)
#define cap_gethostbyaddr(chan, addr, len, type) gethostbyaddr(addr, len, type)
#endif
#endif /* !_CAP_NETWORK_H_ */

16
lib/libcasper/services/cap_net/tests/Makefile Normal file
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@ -0,0 +1,16 @@
# $FreeBSD$
.include <src.opts.mk>
ATF_TESTS_C= net_test
.if ${MK_CASPER} != "no"
LIBADD+= casper
LIBADD+= cap_net
CFLAGS+=-DWITH_CASPER
.endif
LIBADD+= nv
WARNS?= 3
.include <bsd.test.mk>

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lib/libcasper/services/cap_net/tests/net_test.c Normal file
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2
share/mk/src.libnames.mk
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@ -89,6 +89,7 @@ _LIBRARIES= \
cap_dns \
cap_fileargs \
cap_grp \
cap_net \
cap_pwd \
cap_sysctl \
cap_syslog \
@ -637,6 +638,7 @@ LIBBSNMPDIR= ${OBJTOP}/lib/libbsnmp/libbsnmp
LIBCASPERDIR= ${OBJTOP}/lib/libcasper/libcasper
LIBCAP_DNSDIR= ${OBJTOP}/lib/libcasper/services/cap_dns
LIBCAP_GRPDIR= ${OBJTOP}/lib/libcasper/services/cap_grp
LIBCAP_NETDIR= ${OBJTOP}/lib/libcasper/services/cap_net
LIBCAP_PWDDIR= ${OBJTOP}/lib/libcasper/services/cap_pwd
LIBCAP_SYSCTLDIR= ${OBJTOP}/lib/libcasper/services/cap_sysctl
LIBCAP_SYSLOGDIR= ${OBJTOP}/lib/libcasper/services/cap_syslog