/* $NetBSD: lpf.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $ */ /* lpf.c Linux packet filter code, contributed by Brian Murrel at Interlinx Support Services in Vancouver, B.C. */ /* * Copyright (C) 2004-2022 Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996-2003 by Internet Software Consortium * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. * * 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. * PO Box 360 * Newmarket, NH 03857 USA * * https://www.isc.org/ */ #include __RCSID("$NetBSD: lpf.c,v 1.2.6.1 2024/02/29 11:39:17 martin Exp $"); #include "dhcpd.h" #if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE) #include #include #include #include #include #include #include #include "includes/netinet/ip.h" #include "includes/netinet/udp.h" #include "includes/netinet/if_ether.h" #endif #if defined (USE_LPF_RECEIVE) || defined (USE_LPF_HWADDR) #include #include #include #endif #if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE) /* 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; union { struct sockaddr_ll ll; struct sockaddr common; } sa; struct ifreq ifr; /* Make an LPF socket. */ if ((sock = socket(PF_PACKET, SOCK_RAW, 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"); } memset (&ifr, 0, sizeof ifr); strncpy (ifr.ifr_name, (const char *)info -> ifp, sizeof ifr.ifr_name); ifr.ifr_name[IFNAMSIZ-1] = '\0'; if (ioctl (sock, SIOCGIFINDEX, &ifr)) log_fatal ("Failed to get interface index: %m"); /* Bind to the interface name */ memset (&sa, 0, sizeof sa); sa.ll.sll_family = AF_PACKET; sa.ll.sll_ifindex = ifr.ifr_ifindex; if (bind (sock, &sa.common, 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"); } get_hw_addr(info->name, &info->hw_address); 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(RELAY_PORT) extern struct sock_filter dhcp_bpf_relay_filter []; extern int dhcp_bpf_relay_filter_len; #endif #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); #ifdef PACKET_AUXDATA { int val = 1; if (setsockopt(info->rfdesc, SOL_PACKET, PACKET_AUXDATA, &val, sizeof(val)) < 0) { if (errno != ENOPROTOOPT) { log_fatal ("Failed to set auxiliary packet data: %m"); } } } #endif #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; memset(&p, 0, sizeof(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 */ #if defined(RELAY_PORT) if (relay_port) { /* * If user defined relay UDP port, we need to filter * also on the user UDP port. */ p.len = dhcp_bpf_relay_filter_len; p.filter = dhcp_bpf_relay_filter; dhcp_bpf_relay_filter [10].k = ntohs (relay_port); } #endif dhcp_bpf_filter [8].k = ntohs (*libdhcp_callbacks.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; memset(&p, 0, sizeof(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 (*libdhcp_callbacks.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; int result; int fudge; if (!strcmp (interface -> name, "fallback")) return send_fallback (interface, packet, raw, len, from, to, hto); if (hto == NULL && interface->anycast_mac_addr.hlen) hto = &interface->anycast_mac_addr; /* 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); result = write(interface->wfdesc, buf + fudge, ibufp + len - fudge); 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 length = 0; int offset = 0; int csum_ready = 1; unsigned char ibuf [1536]; unsigned bufix = 0; unsigned paylen; struct iovec iov = { .iov_base = ibuf, .iov_len = sizeof ibuf, }; #ifdef PACKET_AUXDATA /* * We only need cmsgbuf if we are getting the aux data and we * only get the auxdata if it is actually defined */ unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))]; struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1, .msg_control = cmsgbuf, .msg_controllen = sizeof(cmsgbuf), }; #else struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1, .msg_control = NULL, .msg_controllen = 0, }; #endif /* PACKET_AUXDATA */ length = recvmsg (interface->rfdesc, &msg, 0); if (length <= 0) return length; #ifdef PACKET_AUXDATA { /* Use auxiliary packet data to: * * a. Weed out extraneous VLAN-tagged packets - If the NIC driver is * handling VLAN encapsulation (i.e. stripping/adding VLAN tags), * then an inbound VLAN packet will be seen twice: Once by * the parent interface (e.g. eth0) with a VLAN tag != 0; and once * by the vlan interface (e.g. eth0.n) with a VLAN tag of 0 (i.e none). * We want to discard the packet sent to the parent and thus respond * only over the vlan interface. (Drivers for Intel PRO/1000 series * NICs perform VLAN encapsulation, while drivers for PCnet series * do not, for example. The linux kernel makes stripped vlan info * visible to user space via CMSG/auxdata, this appears to not be * true for BSD OSs.). NOTE: this is only supported on linux flavors * which define the tpacket_auxdata.tp_vlan_tci. * * b. Determine if checksum is valid for use. It may not be if * checksum offloading is enabled on the interface. */ struct cmsghdr *cmsg; for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) { if (cmsg->cmsg_level == SOL_PACKET && cmsg->cmsg_type == PACKET_AUXDATA) { struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg); #ifdef VLAN_TCI_PRESENT /* Discard packets with stripped vlan id */ /* VLAN ID is only bottom 12-bits of TCI */ if (aux->tp_vlan_tci & 0x0fff) return 0; #endif csum_ready = ((aux->tp_status & TP_STATUS_CSUMNOTREADY) ? 0 : 1); } } } #endif /* PACKET_AUXDATA */ 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)length, &paylen, csum_ready); /* If the IP or UDP checksum was bad, skip the packet... */ if (offset < 0) return 0; bufix += offset; length -= offset; if (length < paylen) log_fatal("Internal inconsistency at %s:%d.", MDL); /* Copy out the data in the packet... */ memcpy(buf, &ibuf[bufix], paylen); return paylen; } 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 #if defined (USE_LPF_RECEIVE) || defined (USE_LPF_HWADDR) void get_hw_addr(const char *name, struct hardware *hw) { int sock; struct ifreq tmp; struct sockaddr *sa; if (strlen(name) >= sizeof(tmp.ifr_name)) { log_fatal("Device name too long: \"%s\"", name); } sock = socket(AF_INET, SOCK_DGRAM, 0); if (sock < 0) { log_fatal("Can't create socket for \"%s\": %m", name); } memset(&tmp, 0, sizeof(tmp)); strcpy(tmp.ifr_name, name); if (ioctl(sock, SIOCGIFHWADDR, &tmp) < 0) { log_fatal("Error getting hardware address for \"%s\": %m", name); } sa = &tmp.ifr_hwaddr; switch (sa->sa_family) { case ARPHRD_ETHER: hw->hlen = 7; hw->hbuf[0] = HTYPE_ETHER; memcpy(&hw->hbuf[1], sa->sa_data, 6); break; case ARPHRD_IEEE802: #ifdef ARPHRD_IEEE802_TR case ARPHRD_IEEE802_TR: #endif /* ARPHRD_IEEE802_TR */ hw->hlen = 7; hw->hbuf[0] = HTYPE_IEEE802; memcpy(&hw->hbuf[1], sa->sa_data, 6); break; case ARPHRD_FDDI: hw->hlen = 7; hw->hbuf[0] = HTYPE_FDDI; memcpy(&hw->hbuf[1], sa->sa_data, 6); break; default: log_fatal("Unsupported device type %ld for \"%s\"", (long int)sa->sa_family, name); } close(sock); } #endif