diff options
Diffstat (limited to 'common/lpf.c')
| -rw-r--r-- | common/lpf.c | 537 |
1 files changed, 537 insertions, 0 deletions
diff --git a/common/lpf.c b/common/lpf.c new file mode 100644 index 0000000..6fe4954 --- /dev/null +++ b/common/lpf.c @@ -0,0 +1,537 @@ +/* lpf.c + + Linux packet filter code, contributed by Brian Murrel at Interlinx + Support Services in Vancouver, B.C. */ + +/* + * Copyright (c) 2014-2015 by Internet Systems Consortium, Inc. ("ISC") + * Copyright (c) 2009,2012 by Internet Systems Consortium, Inc. ("ISC") + * Copyright (c) 2004,2007 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 + * <info@isc.org> + * https://www.isc.org/ + */ + +#include "dhcpd.h" +#if defined (USE_LPF_SEND) || defined (USE_LPF_RECEIVE) +#include <sys/ioctl.h> +#include <sys/uio.h> +#include <errno.h> + +#include <asm/types.h> +#include <linux/filter.h> +#include <linux/if_ether.h> +#include <linux/if_packet.h> +#include <netinet/in_systm.h> +#include "includes/netinet/ip.h" +#include "includes/netinet/udp.h" +#include "includes/netinet/if_ether.h" +#include <net/if.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; + 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 (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 */ + 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; + + 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 (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; + unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))]; + struct iovec iov = { + .iov_base = ibuf, + .iov_len = sizeof ibuf, + }; + struct msghdr msg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = cmsgbuf, + .msg_controllen = sizeof(cmsgbuf), + }; + + 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); + /* Discard packets with stripped vlan id */ + +#ifdef VLAN_TCI_PRESENT + if (aux->tp_vlan_tci != 0) + return 0; +#endif + + csum_ready = ((aux->tp_status & TP_STATUS_CSUMNOTREADY) + ? 0 : 1); + } + } + + } +#endif + + 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); + } +} + +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 |