Tuesday, October 30, 2018

Re: drop privileges for net/arpwatch

Hi,

Am Dienstag, Oktober 30, 2018 08:58 CET, Antoine Jacoutot <ajacoutot@bsdfrog.org> schrieb:

> > > > > On Mon, Oct 29, 2018 at 02:58:11PM +0100, Sebastian Reitenbach wrote:
> > > > > > Hi,
> > > > > >
> > > > > > attached patch updates arpwatch to add -u <username> flag, to drop privileges
> > > > > > to non-privileged user after startup. Patch taken from Debian/Ubuntu, which
> > > > > > originates from RedHat. user/group _arpwatch added to PLIST,
> > > > > > and a user to be added to users.list
> > > > > >
> > > > > > rc script is updated to add -u _arpwatch user to to the daemon.
> > > > > > manpage.
> > > > > >
> > > > > > any comments, objections, or even OK?
> > > > > >
> >
> > > > -daemon="${TRUEPREFIX}/sbin/arpwatch"
> > > > +daemon="${TRUEPREFIX}/sbin/arpwatch -u _arpwatch"
> > >
> > > As I mentioned in my former mail, please put this in daemon_flags.
> > >
> >
> > Do, I overlooked that comment. Meanwhile I also recognized, arpwatch has to
> > be able to write to /var/arpwatch, not only to the arp.dat file in there, it seems
> > to create some temporary files there as well. So also for the @sample /var/arpwatch
> > change @user
> > Updated diff with these two additional changes below.
>
> I think you should s/var/${VARBASE}/
>
that I haven't left alone as it was before, but here you go, also had to update Makefile and
two of the patches with ${VARBASE}

Index: Makefile
===================================================================
RCS file: /cvs/ports/net/arpwatch/Makefile,v
retrieving revision 1.49
diff -u -r1.49 Makefile
--- Makefile 24 Jul 2018 18:59:20 -0000 1.49
+++ Makefile 30 Oct 2018 12:57:00 -0000
@@ -3,7 +3,7 @@
COMMENT= monitor arp & rarp requests

DISTNAME= arpwatch-2.1a15
-REVISION= 18
+REVISION= 19
CATEGORIES= net

MASTER_SITES= ftp://ftp.ee.lbl.gov/
@@ -16,7 +16,7 @@
WANTLIB= c pcap

CONFIGURE_STYLE= gnu
-MAKE_FLAGS+= ARPDIR=/var/arpwatch
+MAKE_FLAGS+= ARPDIR=${VARBASE}/arpwatch

# this provides an up-to-date pregenerated ethercodes.dat file
RUN_DEPENDS= net/arp-scan,-mac
@@ -24,6 +24,10 @@
NO_TEST= Yes

EXAMPLESDIR= ${PREFIX}/share/examples/arpwatch
+SUBST_VARS += VARBASE
+
+pre-build:
+ ${SUBST_CMD} ${WRKSRC}/arpsnmp.8 ${WRKSRC}/arpwatch.8

do-install:
@sed -i 's,awk -f ,awk -f ${EXAMPLESDIR}/', ${WRKSRC}/massagevendor
Index: patches/patch-arpsnmp.8
===================================================================
RCS file: /cvs/ports/net/arpwatch/patches/patch-arpsnmp.8,v
retrieving revision 1.2
diff -u -r1.2 patch-arpsnmp.8
--- patches/patch-arpsnmp.8 11 May 2018 08:13:26 -0000 1.2
+++ patches/patch-arpsnmp.8 30 Oct 2018 12:57:00 -0000
@@ -8,7 +8,7 @@
.nh
.nf
-/usr/operator/arpwatch - default directory
-+/var/arpwatch - default directory
++${VARBASE}/arpwatch - default directory
arp.dat - ethernet/ip address database
ethercodes.dat - vendor ethernet block list
.ad
Index: patches/patch-arpwatch.8
===================================================================
RCS file: /cvs/ports/net/arpwatch/patches/patch-arpwatch.8,v
retrieving revision 1.1
diff -u -r1.1 patch-arpwatch.8
--- patches/patch-arpwatch.8 1 Jun 2001 23:36:32 -0000 1.1
+++ patches/patch-arpwatch.8 30 Oct 2018 12:57:00 -0000
@@ -1,13 +1,45 @@
$OpenBSD: patch-arpwatch.8,v 1.1 2001/06/01 23:36:32 jakob Exp $

---- arpwatch.8.orig Sat Jun 2 01:22:23 2001
-+++ arpwatch.8 Sat Jun 2 01:22:47 2001
-@@ -152,7 +152,7 @@ addresses was a DECnet address.
+Add -u flag, to drop privileges to that user given
+
+Index: arpwatch.8
+--- arpwatch.8.orig
++++ arpwatch.8
+@@ -43,6 +43,9 @@ arpwatch - keep track of ethernet/ip address pairings
+ ]] [
+ .B -r
+ .I file
++] [
++.B -u
++.I username
+ ]
+ .ad
+ .SH DESCRIPTION
+@@ -94,6 +97,18 @@ of reading from the network. In this case,
+ .B arpwatch
+ does not fork.
+ .LP
++The
++.B -u
++flag instructs
++.B arpwatch
++to drop root privileges and change the UID to
++.I username
++and GID to the primary group of
++.I username .
++This is recommended for security reasons, but
++.I username
++has to have write access to the default directory.
++.LP
+ Note that an empty
+ .I arp.dat
+ file must be created before the first time you run
+@@ -152,7 +167,7 @@ addresses was a DECnet address.
.na
.nh
.nf
-/usr/operator/arpwatch - default directory
-+/var/arpwatch - default directory
++${VARBASE}/arpwatch - default directory
arp.dat - ethernet/ip address database
ethercodes.dat - vendor ethernet block list
.ad
Index: patches/patch-arpwatch_c
===================================================================
RCS file: /cvs/ports/net/arpwatch/patches/patch-arpwatch_c,v
retrieving revision 1.1
diff -u -r1.1 patch-arpwatch_c
--- patches/patch-arpwatch_c 15 May 2018 19:10:24 -0000 1.1
+++ patches/patch-arpwatch_c 30 Oct 2018 12:57:00 -0000
@@ -2,11 +2,80 @@

- Do not bail if the interface does not have an IP assigned.
- time_t format string fixes
+- add -u flag, to drop privileges to that user

Index: arpwatch.c
--- arpwatch.c.orig
+++ arpwatch.c
-@@ -223,9 +223,11 @@ main(int argc, char **argv)
+@@ -63,6 +63,9 @@ struct rtentry;
+ #include <syslog.h>
+ #include <unistd.h>
+
++#include <pwd.h>
++#include <grp.h>
++
+ #include <pcap.h>
+
+ #include "gnuc.h"
+@@ -141,6 +144,24 @@ int sanity_ether(struct ether_header *, struct ether_a
+ int sanity_fddi(struct fddi_header *, struct ether_arp *, int);
+ __dead void usage(void) __attribute__((volatile));
+
++void dropprivileges(const char* user)
++{
++ struct passwd* pw;
++ pw = getpwnam( user );
++ if ( pw ) {
++ if ( initgroups(pw->pw_name, pw->pw_gid) != 0 || setgid(pw->pw_gid) != 0 ||
++ setuid(pw->pw_uid) != 0 ) {
++ syslog(LOG_ERR, "Couldn't change to '%.32s' uid=%d gid=%d", user,pw->pw_uid, pw->pw_gid);
++ exit(1);
++ }
++ }
++ else {
++ syslog(LOG_ERR, "Couldn't find user '%.32s' in /etc/passwd", user);
++ exit(1);
++ }
++ syslog(LOG_INFO, "Running as uid=%d gid=%d", getuid(), getgid());
++}
++
+ int
+ main(int argc, char **argv)
+ {
+@@ -153,6 +174,7 @@ main(int argc, char **argv)
+ register char *interface, *rfilename;
+ struct bpf_program code;
+ char errbuf[PCAP_ERRBUF_SIZE];
++ char* username = NULL;
+
+ if (argv[0] == NULL)
+ prog = "arpwatch";
+@@ -170,7 +192,7 @@ main(int argc, char **argv)
+ interface = NULL;
+ rfilename = NULL;
+ pd = NULL;
+- while ((op = getopt(argc, argv, "df:i:n:Nr:")) != EOF)
++ while ((op = getopt(argc, argv, "df:i:n:Nr:u:")) != EOF)
+ switch (op) {
+
+ case 'd':
+@@ -202,6 +224,15 @@ main(int argc, char **argv)
+ rfilename = optarg;
+ break;
+
++ case 'u':
++ if ( optarg ) {
++ username = strdup(optarg);
++ } else {
++ fprintf(stderr, "%s: Need username after -u\n", prog);
++ usage();
++ }
++ break;
++
+ default:
+ usage();
+ }
+@@ -223,9 +254,11 @@ main(int argc, char **argv)

/* Determine network and netmask */
if (pcap_lookupnet(interface, &net, &netmask, errbuf) < 0) {
@@ -21,7 +90,26 @@
}

/* Drop into the background if not debugging */
-@@ -401,7 +403,7 @@ process_ether(register u_char *u, register const struc
+@@ -279,12 +312,16 @@ main(int argc, char **argv)
+

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