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From: Pawel Jakub Dawidek <pjd@FreeBSD.org>
Date: Wed, 3 Jul 2013 22:16:02 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
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Subject: svn commit: r252628 - head/sbin/dhclient
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Author: pjd
Date: Wed Jul  3 22:16:02 2013
New Revision: 252628
URL: http://svnweb.freebsd.org/changeset/base/252628

Log:
  MFp4 @229482:
  
  - Limit bpf descriptor in unprivileged process to CAP_POLL_EVENT, CAP_READ and
    allow for SIOCGIFFLAGS, SIOCGIFMEDIA ioctls.
  - While here limit bpf descriptor in privileged process to only CAP_WRITE.
  
  Reviewed by:	brooks
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sbin/dhclient/bpf.c

Modified: head/sbin/dhclient/bpf.c
==============================================================================
--- head/sbin/dhclient/bpf.c	Wed Jul  3 22:14:12 2013	(r252627)
+++ head/sbin/dhclient/bpf.c	Wed Jul  3 22:16:02 2013	(r252628)
@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
 
 #include "dhcpd.h"
 #include "privsep.h"
+#include <sys/capability.h>
 #include <sys/ioctl.h>
 #include <sys/uio.h>
 
@@ -159,6 +160,9 @@ if_register_send(struct interface_info *
 	if (ioctl(info->wfdesc, BIOCLOCK, NULL) < 0)
 		error("Cannot lock bpf");
 
+	if (cap_rights_limit(info->wfdesc, CAP_WRITE) < 0 && errno != ENOSYS)
+		error("Can't limit bpf descriptor: %m");
+
 	/*
 	 * Use raw socket for unicast send.
 	 */
@@ -208,6 +212,7 @@ int dhcp_bpf_filter_len = sizeof(dhcp_bp
 void
 if_register_receive(struct interface_info *info)
 {
+	static const unsigned long cmds[2] = { SIOCGIFFLAGS, SIOCGIFMEDIA };
 	struct bpf_version v;
 	struct bpf_program p;
 	int flag = 1, sz;
@@ -258,6 +263,13 @@ if_register_receive(struct interface_inf
 
 	if (ioctl(info->rfdesc, BIOCLOCK, NULL) < 0)
 		error("Cannot lock bpf");
+
+	if (cap_rights_limit(info->rfdesc,
+	    CAP_IOCTL | CAP_POLL_EVENT | CAP_READ) < 0 && errno != ENOSYS) {
+		error("Can't limit bpf descriptor: %m");
+	}
+	if (cap_ioctls_limit(info->rfdesc, cmds, 2) < 0 && errno != ENOSYS)
+		error("Can't limit ioctls for bpf descriptor: %m");
 }
 
 void