413 lines
12 KiB
C
413 lines
12 KiB
C
/* lpf.c
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Linux packet filter code, contributed by Brian Murrel at Interlinx
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Support Services in Vancouver, B.C. */
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/*
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* Copyright (c) 1996-2000 Internet Software Consortium.
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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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*
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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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* 3. Neither the name of The Internet Software Consortium nor the names
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* of its contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
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* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* 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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#ifndef lint
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static char copyright[] =
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"$Id: lpf.c,v 1.1.1.7 2000/09/04 23:10:11 mellon Exp $ Copyright (c) 1996-2000 The Internet Software Consortium. All rights reserved.\n";
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#endif /* not lint */
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#include "dhcpd.h"
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#if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE)
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#include <sys/ioctl.h>
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#include <sys/uio.h>
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#include <asm/types.h>
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#include <linux/filter.h>
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#include <linux/if_ether.h>
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#include <netinet/in_systm.h>
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#include "includes/netinet/ip.h"
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#include "includes/netinet/udp.h"
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#include "includes/netinet/if_ether.h"
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/* Reinitializes the specified interface after an address change. This
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is not required for packet-filter APIs. */
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#ifdef USE_LPF_SEND
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void if_reinitialize_send (info)
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struct interface_info *info;
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{
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}
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#endif
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#ifdef USE_LPF_RECEIVE
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void if_reinitialize_receive (info)
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struct interface_info *info;
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{
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}
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#endif
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/* Called by get_interface_list for each interface that's discovered.
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Opens a packet filter for each interface and adds it to the select
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mask. */
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int if_register_lpf (info)
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struct interface_info *info;
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{
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int sock;
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char filename[50];
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int b;
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struct sockaddr sa;
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/* Make an LPF socket. */
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if ((sock = socket(PF_PACKET, SOCK_PACKET,
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htons((short)ETH_P_ALL))) < 0) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT || errno == EINVAL) {
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log_error ("socket: %m - make sure");
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log_error ("CONFIG_PACKET (Packet socket) %s",
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"and CONFIG_FILTER");
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log_error ("(Socket Filtering) are enabled %s",
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"in your kernel");
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log_fatal ("configuration!");
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}
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log_fatal ("Open a socket for LPF: %m");
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}
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/* Bind to the interface name */
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memset (&sa, 0, sizeof sa);
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sa.sa_family = AF_PACKET;
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strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data);
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if (bind (sock, &sa, sizeof sa)) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT || errno == EINVAL) {
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log_error ("socket: %m - make sure");
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log_error ("CONFIG_PACKET (Packet socket) %s",
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"and CONFIG_FILTER");
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log_error ("(Socket Filtering) are enabled %s",
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"in your kernel");
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log_fatal ("configuration!");
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}
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log_fatal ("Bind socket to interface: %m");
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}
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return sock;
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}
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#endif /* USE_LPF_SEND || USE_LPF_RECEIVE */
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#ifdef USE_LPF_SEND
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void if_register_send (info)
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struct interface_info *info;
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{
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/* If we're using the lpf API for sending and receiving,
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we don't need to register this interface twice. */
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#ifndef USE_LPF_RECEIVE
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info -> wfdesc = if_register_lpf (info);
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#else
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info -> wfdesc = info -> rfdesc;
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#endif
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if (!quiet_interface_discovery)
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log_info ("Sending on LPF/%s/%s%s%s",
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info -> name,
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print_hw_addr (info -> hw_address.hbuf [0],
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info -> hw_address.hlen - 1,
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&info -> hw_address.hbuf [1]),
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(info -> shared_network ? "/" : ""),
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(info -> shared_network ?
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info -> shared_network -> name : ""));
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}
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void if_deregister_send (info)
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struct interface_info *info;
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{
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/* don't need to close twice if we are using lpf for sending and
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receiving */
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#ifndef USE_LPF_RECEIVE
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/* for LPF this is simple, packet filters are removed when sockets
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are closed */
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close (info -> wfdesc);
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#endif
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info -> wfdesc = -1;
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if (!quiet_interface_discovery)
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log_info ("Disabling output on LPF/%s/%s%s%s",
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info -> name,
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print_hw_addr (info -> hw_address.hbuf [0],
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info -> hw_address.hlen - 1,
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&info -> hw_address.hbuf [1]),
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(info -> shared_network ? "/" : ""),
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(info -> shared_network ?
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info -> shared_network -> name : ""));
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}
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#endif /* USE_LPF_SEND */
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#ifdef USE_LPF_RECEIVE
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/* Defined in bpf.c. We can't extern these in dhcpd.h without pulling
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in bpf includes... */
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extern struct sock_filter dhcp_bpf_filter [];
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extern int dhcp_bpf_filter_len;
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extern struct sock_filter dhcp_bpf_tr_filter [];
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extern int dhcp_bpf_tr_filter_len;
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static void lpf_gen_filter_setup (struct interface_info *);
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static void lpf_tr_filter_setup (struct interface_info *);
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void if_register_receive (info)
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struct interface_info *info;
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{
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/* Open a LPF device and hang it on this interface... */
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info -> rfdesc = if_register_lpf (info);
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if (info -> hw_address.hbuf [0] == HTYPE_IEEE802)
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lpf_tr_filter_setup (info);
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else
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lpf_gen_filter_setup (info);
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if (!quiet_interface_discovery)
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log_info ("Listening on LPF/%s/%s%s%s",
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info -> name,
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print_hw_addr (info -> hw_address.hbuf [0],
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info -> hw_address.hlen - 1,
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&info -> hw_address.hbuf [1]),
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(info -> shared_network ? "/" : ""),
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(info -> shared_network ?
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info -> shared_network -> name : ""));
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}
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void if_deregister_receive (info)
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struct interface_info *info;
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{
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/* for LPF this is simple, packet filters are removed when sockets
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are closed */
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close (info -> rfdesc);
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info -> rfdesc = -1;
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if (!quiet_interface_discovery)
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log_info ("Disabling input on LPF/%s/%s%s%s",
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info -> name,
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print_hw_addr (info -> hw_address.hbuf [0],
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info -> hw_address.hlen - 1,
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&info -> hw_address.hbuf [1]),
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(info -> shared_network ? "/" : ""),
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(info -> shared_network ?
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info -> shared_network -> name : ""));
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}
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static void lpf_gen_filter_setup (info)
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struct interface_info *info;
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{
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struct sock_fprog p;
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/* Set up the bpf filter program structure. This is defined in
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bpf.c */
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p.len = dhcp_bpf_filter_len;
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p.filter = dhcp_bpf_filter;
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/* Patch the server port into the LPF program...
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XXX changes to filter program may require changes
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to the insn number(s) used below! XXX */
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dhcp_bpf_filter [8].k = ntohs ((short)local_port);
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if (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p,
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sizeof p) < 0) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT) {
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log_error ("socket: %m - make sure");
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log_error ("CONFIG_PACKET (Packet socket) %s",
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"and CONFIG_FILTER");
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log_error ("(Socket Filtering) are enabled %s",
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"in your kernel");
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log_fatal ("configuration!");
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}
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log_fatal ("Can't install packet filter program: %m");
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}
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}
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static void lpf_tr_filter_setup (info)
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struct interface_info *info;
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{
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struct sock_fprog p;
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/* Set up the bpf filter program structure. This is defined in
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bpf.c */
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p.len = dhcp_bpf_tr_filter_len;
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p.filter = dhcp_bpf_tr_filter;
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/* Patch the server port into the LPF program...
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XXX changes to filter program may require changes
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XXX to the insn number(s) used below!
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XXX Token ring filter is null - when/if we have a filter
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XXX that's not, we'll need this code.
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XXX dhcp_bpf_filter [?].k = ntohs (local_port); */
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if (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p,
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sizeof p) < 0) {
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if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT ||
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errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT ||
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errno == EAFNOSUPPORT) {
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log_error ("socket: %m - make sure");
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log_error ("CONFIG_PACKET (Packet socket) %s",
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"and CONFIG_FILTER");
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log_error ("(Socket Filtering) are enabled %s",
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"in your kernel");
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log_fatal ("configuration!");
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}
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log_fatal ("Can't install packet filter program: %m");
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}
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}
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#endif /* USE_LPF_RECEIVE */
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#ifdef USE_LPF_SEND
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ssize_t send_packet (interface, packet, raw, len, from, to, hto)
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struct interface_info *interface;
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struct packet *packet;
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struct dhcp_packet *raw;
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size_t len;
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struct in_addr from;
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struct sockaddr_in *to;
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struct hardware *hto;
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{
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unsigned hbufp = 0, ibufp = 0;
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double hh [16];
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double ih [1536 / sizeof (double)];
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unsigned char *buf = (unsigned char *)ih;
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struct sockaddr sa;
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int result;
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int fudge;
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if (!strcmp (interface -> name, "fallback"))
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return send_fallback (interface, packet, raw,
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len, from, to, hto);
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/* Assemble the headers... */
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assemble_hw_header (interface, (unsigned char *)hh, &hbufp, hto);
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fudge = hbufp % 4; /* IP header must be word-aligned. */
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memcpy (buf + fudge, (unsigned char *)hh, hbufp);
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ibufp = hbufp + fudge;
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assemble_udp_ip_header (interface, buf, &ibufp, from.s_addr,
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to -> sin_addr.s_addr, to -> sin_port,
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(unsigned char *)raw, len);
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memcpy (buf + ibufp, raw, len);
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/* For some reason, SOCK_PACKET sockets can't be connected,
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so we have to do a sentdo every time. */
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memset (&sa, 0, sizeof sa);
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sa.sa_family = AF_PACKET;
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strncpy (sa.sa_data,
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(const char *)interface -> ifp, sizeof sa.sa_data);
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result = sendto (interface -> wfdesc,
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buf + fudge, ibufp + len - fudge, 0, &sa, sizeof sa);
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if (result < 0)
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log_error ("send_packet: %m");
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return result;
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}
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#endif /* USE_LPF_SEND */
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#ifdef USE_LPF_RECEIVE
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ssize_t receive_packet (interface, buf, len, from, hfrom)
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struct interface_info *interface;
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unsigned char *buf;
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size_t len;
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struct sockaddr_in *from;
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struct hardware *hfrom;
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{
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int nread;
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int length = 0;
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int offset = 0;
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unsigned char ibuf [1500];
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unsigned bufix = 0;
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length = read (interface -> rfdesc, ibuf, sizeof ibuf);
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if (length <= 0)
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return length;
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bufix = 0;
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/* Decode the physical header... */
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offset = decode_hw_header (interface, ibuf, bufix, hfrom);
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/* If a physical layer checksum failed (dunno of any
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physical layer that supports this, but WTH), skip this
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packet. */
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if (offset < 0) {
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return 0;
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}
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bufix += offset;
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length -= offset;
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/* Decode the IP and UDP headers... */
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offset = decode_udp_ip_header (interface, ibuf, bufix, from,
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(unsigned char *)0, (unsigned)length);
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/* If the IP or UDP checksum was bad, skip the packet... */
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if (offset < 0)
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return 0;
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bufix += offset;
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length -= offset;
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/* Copy out the data in the packet... */
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memcpy (buf, &ibuf [bufix], length);
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return length;
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}
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int can_unicast_without_arp (ip)
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struct interface_info *ip;
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{
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return 1;
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}
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int can_receive_unicast_unconfigured (ip)
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struct interface_info *ip;
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{
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return 1;
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}
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int supports_multiple_interfaces (ip)
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struct interface_info *ip;
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{
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return 1;
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}
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void maybe_setup_fallback ()
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{
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isc_result_t status;
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struct interface_info *fbi = (struct interface_info *)0;
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if (setup_fallback (&fbi, MDL)) {
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if_register_fallback (fbi);
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status = omapi_register_io_object ((omapi_object_t *)fbi,
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if_readsocket, 0,
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fallback_discard, 0, 0);
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if (status != ISC_R_SUCCESS)
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log_fatal ("Can't register I/O handle for %s: %s",
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fbi -> name, isc_result_totext (status));
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interface_dereference (&fbi, MDL);
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}
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}
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#endif
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