/* lpf.c Linux packet filter code, contributed by Brian Murrel at Interlinx Support Services in Vancouver, B.C. */ /* * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996-2003 by Internet Software Consortium * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. * * Internet Systems Consortium, Inc. * 950 Charter Street * Redwood City, CA 94063 * * http://www.isc.org/ */ #ifndef lint static char copyright[] = "$Id: lpf.c,v 1.29.2.2 2004/06/10 17:59:19 dhankins Exp $ Copyright (c) 2004 Internet Systems Consortium. All rights reserved.\n"; #endif /* not lint */ #include "dhcpd.h" #if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE) #include #include #include #include #include #include #include "includes/netinet/ip.h" #include "includes/netinet/udp.h" #include "includes/netinet/if_ether.h" /* Reinitializes the specified interface after an address change. This is not required for packet-filter APIs. */ #ifdef USE_LPF_SEND void if_reinitialize_send (info) struct interface_info *info; { } #endif #ifdef USE_LPF_RECEIVE void if_reinitialize_receive (info) struct interface_info *info; { } #endif /* Called by get_interface_list for each interface that's discovered. Opens a packet filter for each interface and adds it to the select mask. */ int if_register_lpf (info) struct interface_info *info; { int sock; char filename[50]; int b; struct sockaddr sa; /* Make an LPF socket. */ if ((sock = socket(PF_PACKET, SOCK_PACKET, htons((short)ETH_P_ALL))) < 0) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT || errno == EINVAL) { log_error ("socket: %m - make sure"); log_error ("CONFIG_PACKET (Packet socket) %s", "and CONFIG_FILTER"); log_error ("(Socket Filtering) are enabled %s", "in your kernel"); log_fatal ("configuration!"); } log_fatal ("Open a socket for LPF: %m"); } /* Bind to the interface name */ memset (&sa, 0, sizeof sa); sa.sa_family = AF_PACKET; strncpy (sa.sa_data, (const char *)info -> ifp, sizeof sa.sa_data); if (bind (sock, &sa, sizeof sa)) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT || errno == EINVAL) { log_error ("socket: %m - make sure"); log_error ("CONFIG_PACKET (Packet socket) %s", "and CONFIG_FILTER"); log_error ("(Socket Filtering) are enabled %s", "in your kernel"); log_fatal ("configuration!"); } log_fatal ("Bind socket to interface: %m"); } return sock; } #endif /* USE_LPF_SEND || USE_LPF_RECEIVE */ #ifdef USE_LPF_SEND void if_register_send (info) struct interface_info *info; { /* If we're using the lpf API for sending and receiving, we don't need to register this interface twice. */ #ifndef USE_LPF_RECEIVE info -> wfdesc = if_register_lpf (info); #else info -> wfdesc = info -> rfdesc; #endif if (!quiet_interface_discovery) log_info ("Sending on LPF/%s/%s%s%s", info -> name, print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } void if_deregister_send (info) struct interface_info *info; { /* don't need to close twice if we are using lpf for sending and receiving */ #ifndef USE_LPF_RECEIVE /* for LPF this is simple, packet filters are removed when sockets are closed */ close (info -> wfdesc); #endif info -> wfdesc = -1; if (!quiet_interface_discovery) log_info ("Disabling output on LPF/%s/%s%s%s", info -> name, print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } #endif /* USE_LPF_SEND */ #ifdef USE_LPF_RECEIVE /* Defined in bpf.c. We can't extern these in dhcpd.h without pulling in bpf includes... */ extern struct sock_filter dhcp_bpf_filter []; extern int dhcp_bpf_filter_len; #if defined (HAVE_TR_SUPPORT) extern struct sock_filter dhcp_bpf_tr_filter []; extern int dhcp_bpf_tr_filter_len; static void lpf_tr_filter_setup (struct interface_info *); #endif static void lpf_gen_filter_setup (struct interface_info *); void if_register_receive (info) struct interface_info *info; { /* Open a LPF device and hang it on this interface... */ info -> rfdesc = if_register_lpf (info); #if defined (HAVE_TR_SUPPORT) if (info -> hw_address.hbuf [0] == HTYPE_IEEE802) lpf_tr_filter_setup (info); else #endif lpf_gen_filter_setup (info); if (!quiet_interface_discovery) log_info ("Listening on LPF/%s/%s%s%s", info -> name, print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } void if_deregister_receive (info) struct interface_info *info; { /* for LPF this is simple, packet filters are removed when sockets are closed */ close (info -> rfdesc); info -> rfdesc = -1; if (!quiet_interface_discovery) log_info ("Disabling input on LPF/%s/%s%s%s", info -> name, print_hw_addr (info -> hw_address.hbuf [0], info -> hw_address.hlen - 1, &info -> hw_address.hbuf [1]), (info -> shared_network ? "/" : ""), (info -> shared_network ? info -> shared_network -> name : "")); } static void lpf_gen_filter_setup (info) struct interface_info *info; { struct sock_fprog p; /* Set up the bpf filter program structure. This is defined in bpf.c */ p.len = dhcp_bpf_filter_len; p.filter = dhcp_bpf_filter; /* Patch the server port into the LPF program... XXX changes to filter program may require changes to the insn number(s) used below! XXX */ dhcp_bpf_filter [8].k = ntohs ((short)local_port); if (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p, sizeof p) < 0) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT) { log_error ("socket: %m - make sure"); log_error ("CONFIG_PACKET (Packet socket) %s", "and CONFIG_FILTER"); log_error ("(Socket Filtering) are enabled %s", "in your kernel"); log_fatal ("configuration!"); } log_fatal ("Can't install packet filter program: %m"); } } #if defined (HAVE_TR_SUPPORT) static void lpf_tr_filter_setup (info) struct interface_info *info; { struct sock_fprog p; /* Set up the bpf filter program structure. This is defined in bpf.c */ p.len = dhcp_bpf_tr_filter_len; p.filter = dhcp_bpf_tr_filter; /* Patch the server port into the LPF program... XXX changes to filter program may require changes XXX to the insn number(s) used below! XXX Token ring filter is null - when/if we have a filter XXX that's not, we'll need this code. XXX dhcp_bpf_filter [?].k = ntohs (local_port); */ if (setsockopt (info -> rfdesc, SOL_SOCKET, SO_ATTACH_FILTER, &p, sizeof p) < 0) { if (errno == ENOPROTOOPT || errno == EPROTONOSUPPORT || errno == ESOCKTNOSUPPORT || errno == EPFNOSUPPORT || errno == EAFNOSUPPORT) { log_error ("socket: %m - make sure"); log_error ("CONFIG_PACKET (Packet socket) %s", "and CONFIG_FILTER"); log_error ("(Socket Filtering) are enabled %s", "in your kernel"); log_fatal ("configuration!"); } log_fatal ("Can't install packet filter program: %m"); } } #endif /* HAVE_TR_SUPPORT */ #endif /* USE_LPF_RECEIVE */ #ifdef USE_LPF_SEND ssize_t send_packet (interface, packet, raw, len, from, to, hto) struct interface_info *interface; struct packet *packet; struct dhcp_packet *raw; size_t len; struct in_addr from; struct sockaddr_in *to; struct hardware *hto; { unsigned hbufp = 0, ibufp = 0; double hh [16]; double ih [1536 / sizeof (double)]; unsigned char *buf = (unsigned char *)ih; struct sockaddr sa; int result; int fudge; if (!strcmp (interface -> name, "fallback")) return send_fallback (interface, packet, raw, len, from, to, hto); /* Assemble the headers... */ assemble_hw_header (interface, (unsigned char *)hh, &hbufp, hto); fudge = hbufp % 4; /* IP header must be word-aligned. */ memcpy (buf + fudge, (unsigned char *)hh, hbufp); ibufp = hbufp + fudge; assemble_udp_ip_header (interface, buf, &ibufp, from.s_addr, to -> sin_addr.s_addr, to -> sin_port, (unsigned char *)raw, len); memcpy (buf + ibufp, raw, len); /* For some reason, SOCK_PACKET sockets can't be connected, so we have to do a sentdo every time. */ memset (&sa, 0, sizeof sa); sa.sa_family = AF_PACKET; strncpy (sa.sa_data, (const char *)interface -> ifp, sizeof sa.sa_data); result = sendto (interface -> wfdesc, buf + fudge, ibufp + len - fudge, 0, &sa, sizeof sa); if (result < 0) log_error ("send_packet: %m"); return result; } #endif /* USE_LPF_SEND */ #ifdef USE_LPF_RECEIVE ssize_t receive_packet (interface, buf, len, from, hfrom) struct interface_info *interface; unsigned char *buf; size_t len; struct sockaddr_in *from; struct hardware *hfrom; { int nread; int length = 0; int offset = 0; unsigned char ibuf [1536]; unsigned bufix = 0; length = read (interface -> rfdesc, ibuf, sizeof ibuf); if (length <= 0) return length; bufix = 0; /* Decode the physical header... */ offset = decode_hw_header (interface, ibuf, bufix, hfrom); /* If a physical layer checksum failed (dunno of any physical layer that supports this, but WTH), skip this packet. */ if (offset < 0) { return 0; } bufix += offset; length -= offset; /* Decode the IP and UDP headers... */ offset = decode_udp_ip_header (interface, ibuf, bufix, from, (unsigned char *)0, (unsigned)length); /* If the IP or UDP checksum was bad, skip the packet... */ if (offset < 0) return 0; bufix += offset; length -= offset; /* Copy out the data in the packet... */ memcpy (buf, &ibuf [bufix], length); return length; } int can_unicast_without_arp (ip) struct interface_info *ip; { return 1; } int can_receive_unicast_unconfigured (ip) struct interface_info *ip; { return 1; } int supports_multiple_interfaces (ip) struct interface_info *ip; { return 1; } void maybe_setup_fallback () { isc_result_t status; struct interface_info *fbi = (struct interface_info *)0; if (setup_fallback (&fbi, MDL)) { if_register_fallback (fbi); status = omapi_register_io_object ((omapi_object_t *)fbi, if_readsocket, 0, fallback_discard, 0, 0); if (status != ISC_R_SUCCESS) log_fatal ("Can't register I/O handle for %s: %s", fbi -> name, isc_result_totext (status)); interface_dereference (&fbi, MDL); } } #endif