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Diffstat (limited to 'common/bpf.c')
| -rw-r--r-- | common/bpf.c | 607 |
1 files changed, 607 insertions, 0 deletions
diff --git a/common/bpf.c b/common/bpf.c new file mode 100644 index 0000000..27e55aa --- /dev/null +++ b/common/bpf.c @@ -0,0 +1,607 @@ +/* bpf.c + + BPF socket interface code, originally contributed by Archie Cobbs. */ + +/* + * Copyright (c) 2004,2007,2009,2014 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/ + * + * This software was contributed to Internet Systems Consortium + * by Archie Cobbs. + * + * Patches for FDDI support on Digital Unix were written by Bill + * Stapleton, and maintained for a while by Mike Meredith before he + * managed to get me to integrate them. + */ + +#include "dhcpd.h" +#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) \ + || defined (USE_LPF_RECEIVE) +# if defined (USE_LPF_RECEIVE) +# include <asm/types.h> +# include <linux/filter.h> +# define bpf_insn sock_filter /* Linux: dare to be gratuitously different. */ +# else +# include <sys/ioctl.h> +# include <sys/uio.h> +# include <net/bpf.h> +# include <net/if_types.h> +# if defined (NEED_OSF_PFILT_HACKS) +# include <net/pfilt.h> +# endif +# endif + +#include <netinet/in_systm.h> +#include "includes/netinet/ip.h" +#include "includes/netinet/udp.h" +#include "includes/netinet/if_ether.h" +#endif + +#ifdef USE_BPF_RECEIVE +#include <ifaddrs.h> +#endif + +#include <errno.h> + +/* Reinitializes the specified interface after an address change. This + is not required for packet-filter APIs. */ + +#ifdef USE_BPF_SEND +void if_reinitialize_send (info) + struct interface_info *info; +{ +} +#endif + +#ifdef USE_BPF_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. */ + +#if defined (USE_BPF_SEND) || defined (USE_BPF_RECEIVE) +int if_register_bpf (info) + struct interface_info *info; +{ + int sock; + char filename[50]; + int b; + + /* Open a BPF device */ + for (b = 0; 1; b++) { + /* %Audit% 31 bytes max. %2004.06.17,Safe% */ + sprintf(filename, BPF_FORMAT, b); + sock = open (filename, O_RDWR, 0); + if (sock < 0) { + if (errno == EBUSY) { + continue; + } else { + if (!b) + log_fatal ("No bpf devices.%s%s%s", + " Please read the README", + " section for your operating", + " system."); + log_fatal ("Can't find free bpf: %m"); + } + } else { + break; + } + } + + /* Set the BPF device to point at this interface. */ + if (ioctl (sock, BIOCSETIF, info -> ifp) < 0) + log_fatal ("Can't attach interface %s to bpf device %s: %m", + info -> name, filename); + + get_hw_addr(info->name, &info->hw_address); + + return sock; +} +#endif /* USE_BPF_SEND || USE_BPF_RECEIVE */ + +#ifdef USE_BPF_SEND +void if_register_send (info) + struct interface_info *info; +{ + /* If we're using the bpf API for sending and receiving, + we don't need to register this interface twice. */ +#ifndef USE_BPF_RECEIVE + info -> wfdesc = if_register_bpf (info, interface); +#else + info -> wfdesc = info -> rfdesc; +#endif + if (!quiet_interface_discovery) + log_info ("Sending on BPF/%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; +{ + /* If we're using the bpf API for sending and receiving, + we don't need to register this interface twice. */ +#ifndef USE_BPF_RECEIVE + close (info -> wfdesc); +#endif + info -> wfdesc = -1; + + if (!quiet_interface_discovery) + log_info ("Disabling output on BPF/%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_BPF_SEND */ + +#if defined (USE_BPF_RECEIVE) || defined (USE_LPF_RECEIVE) +/* Packet filter program... + XXX Changes to the filter program may require changes to the constant + offsets used in if_register_send to patch the BPF program! XXX */ + +struct bpf_insn dhcp_bpf_filter [] = { + /* Make sure this is an IP packet... */ + BPF_STMT (BPF_LD + BPF_H + BPF_ABS, 12), + BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 8), + + /* Make sure it's a UDP packet... */ + BPF_STMT (BPF_LD + BPF_B + BPF_ABS, 23), + BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 6), + + /* Make sure this isn't a fragment... */ + BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20), + BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 4, 0), + + /* Get the IP header length... */ + BPF_STMT (BPF_LDX + BPF_B + BPF_MSH, 14), + + /* Make sure it's to the right port... */ + BPF_STMT (BPF_LD + BPF_H + BPF_IND, 16), + BPF_JUMP (BPF_JMP + BPF_JEQ + BPF_K, 67, 0, 1), /* patch */ + + /* If we passed all the tests, ask for the whole packet. */ + BPF_STMT(BPF_RET+BPF_K, (u_int)-1), + + /* Otherwise, drop it. */ + BPF_STMT(BPF_RET+BPF_K, 0), +}; + +#if defined (DEC_FDDI) +struct bpf_insn *bpf_fddi_filter; +#endif + +int dhcp_bpf_filter_len = sizeof dhcp_bpf_filter / sizeof (struct bpf_insn); +#if defined (HAVE_TR_SUPPORT) +struct bpf_insn dhcp_bpf_tr_filter [] = { + /* accept all token ring packets due to variable length header */ + /* if we want to get clever, insert the program here */ + + /* If we passed all the tests, ask for the whole packet. */ + BPF_STMT(BPF_RET+BPF_K, (u_int)-1), + + /* Otherwise, drop it. */ + BPF_STMT(BPF_RET+BPF_K, 0), +}; + +int dhcp_bpf_tr_filter_len = (sizeof dhcp_bpf_tr_filter / + sizeof (struct bpf_insn)); +#endif /* HAVE_TR_SUPPORT */ +#endif /* USE_LPF_RECEIVE || USE_BPF_RECEIVE */ + +#if defined (USE_BPF_RECEIVE) +void if_register_receive (info) + struct interface_info *info; +{ + int flag = 1; + struct bpf_version v; + struct bpf_program p; +#ifdef NEED_OSF_PFILT_HACKS + u_int32_t bits; +#endif +#ifdef DEC_FDDI + int link_layer; +#endif /* DEC_FDDI */ + + /* Open a BPF device and hang it on this interface... */ + info -> rfdesc = if_register_bpf (info); + + /* Make sure the BPF version is in range... */ + if (ioctl (info -> rfdesc, BIOCVERSION, &v) < 0) + log_fatal ("Can't get BPF version: %m"); + + if (v.bv_major != BPF_MAJOR_VERSION || + v.bv_minor < BPF_MINOR_VERSION) + log_fatal ("BPF version mismatch - recompile DHCP!"); + + /* Set immediate mode so that reads return as soon as a packet + comes in, rather than waiting for the input buffer to fill with + packets. */ + if (ioctl (info -> rfdesc, BIOCIMMEDIATE, &flag) < 0) + log_fatal ("Can't set immediate mode on bpf device: %m"); + +#ifdef NEED_OSF_PFILT_HACKS + /* Allow the copyall flag to be set... */ + if (ioctl(info -> rfdesc, EIOCALLOWCOPYALL, &flag) < 0) + log_fatal ("Can't set ALLOWCOPYALL: %m"); + + /* Clear all the packet filter mode bits first... */ + bits = 0; + if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0) + log_fatal ("Can't clear pfilt bits: %m"); + + /* Set the ENBATCH, ENCOPYALL, ENBPFHDR bits... */ + bits = ENBATCH | ENCOPYALL | ENBPFHDR; + if (ioctl (info -> rfdesc, EIOCMBIS, &bits) < 0) + log_fatal ("Can't set ENBATCH|ENCOPYALL|ENBPFHDR: %m"); +#endif + /* Get the required BPF buffer length from the kernel. */ + if (ioctl (info -> rfdesc, BIOCGBLEN, &info -> rbuf_max) < 0) + log_fatal ("Can't get bpf buffer length: %m"); + info -> rbuf = dmalloc (info -> rbuf_max, MDL); + if (!info -> rbuf) + log_fatal ("Can't allocate %ld bytes for bpf input buffer.", + (long)(info -> rbuf_max)); + info -> rbuf_offset = 0; + info -> rbuf_len = 0; + + /* Set up the bpf filter program structure. */ + p.bf_len = dhcp_bpf_filter_len; + +#ifdef DEC_FDDI + /* See if this is an FDDI interface, flag it for later. */ + if (ioctl(info -> rfdesc, BIOCGDLT, &link_layer) >= 0 && + link_layer == DLT_FDDI) { + if (!bpf_fddi_filter) { + bpf_fddi_filter = dmalloc (sizeof bpf_fddi_filter, + MDL); + if (!bpf_fddi_filter) + log_fatal ("No memory for FDDI filter."); + memcpy (bpf_fddi_filter, + dhcp_bpf_filter, sizeof dhcp_bpf_filter); + /* Patch the BPF program to account for the difference + in length between ethernet headers (14), FDDI and + 802.2 headers (16 +8=24, +10). + XXX changes to filter program may require changes to + XXX the insn number(s) used below! */ + bpf_fddi_filter[0].k += 10; + bpf_fddi_filter[2].k += 10; + bpf_fddi_filter[4].k += 10; + bpf_fddi_filter[6].k += 10; + bpf_fddi_filter[7].k += 10; + } + p.bf_insns = bpf_fddi_filter; + } else +#endif /* DEC_FDDI */ + p.bf_insns = dhcp_bpf_filter; + + /* Patch the server port into the BPF program... + XXX changes to filter program may require changes + to the insn number(s) used below! XXX */ + dhcp_bpf_filter [8].k = ntohs (local_port); + + if (ioctl (info -> rfdesc, BIOCSETF, &p) < 0) + log_fatal ("Can't install packet filter program: %m"); + if (!quiet_interface_discovery) + log_info ("Listening on BPF/%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; +{ + close (info -> rfdesc); + info -> rfdesc = -1; + + if (!quiet_interface_discovery) + log_info ("Disabling input on BPF/%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_BPF_RECEIVE */ + +#ifdef USE_BPF_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 hw [4]; + double ip [32]; + struct iovec iov [3]; + int result; + + 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 *)hw, &hbufp, hto); + assemble_udp_ip_header (interface, + (unsigned char *)ip, &ibufp, from.s_addr, + to -> sin_addr.s_addr, to -> sin_port, + (unsigned char *)raw, len); + + /* Fire it off */ + iov [0].iov_base = ((char *)hw); + iov [0].iov_len = hbufp; + iov [1].iov_base = ((char *)ip); + iov [1].iov_len = ibufp; + iov [2].iov_base = (char *)raw; + iov [2].iov_len = len; + + result = writev(interface -> wfdesc, iov, 3); + if (result < 0) + log_error ("send_packet: %m"); + return result; +} +#endif /* USE_BPF_SEND */ + +#ifdef USE_BPF_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; + struct bpf_hdr hdr; + unsigned paylen; + + /* All this complexity is because BPF doesn't guarantee + that only one packet will be returned at a time. We're + getting what we deserve, though - this is a terrible abuse + of the BPF interface. Sigh. */ + + /* Process packets until we get one we can return or until we've + done a read and gotten nothing we can return... */ + + /* If the buffer is empty, fill it. */ + if (interface->rbuf_offset >= interface->rbuf_len) { + length = read(interface->rfdesc, interface->rbuf, + (size_t)interface->rbuf_max); + if (length <= 0) { +#ifdef __FreeBSD__ + if (errno == ENXIO) { +#else + if (errno == EIO) { +#endif + dhcp_interface_remove + ((omapi_object_t *)interface, NULL); + } + return (length); + } + interface->rbuf_offset = 0; + interface->rbuf_len = BPF_WORDALIGN(length); + } + + do { + /* If there isn't room for a whole bpf header, something went + wrong, but we'll ignore it and hope it goes away... XXX */ + if (interface->rbuf_len - + interface->rbuf_offset < sizeof hdr) { + interface->rbuf_offset = interface->rbuf_len; + continue; + } + + /* Copy out a bpf header... */ + memcpy(&hdr, &interface->rbuf[interface->rbuf_offset], + sizeof hdr); + + /* If the bpf header plus data doesn't fit in what's left + of the buffer, stick head in sand yet again... */ + if (interface->rbuf_offset + + hdr.bh_hdrlen + hdr.bh_caplen > interface->rbuf_len) { + interface->rbuf_offset = interface->rbuf_len; + continue; + } + + /* If the captured data wasn't the whole packet, or if + the packet won't fit in the input buffer, all we + can do is drop it. */ + if (hdr.bh_caplen != hdr.bh_datalen) { + interface->rbuf_offset = + BPF_WORDALIGN(interface->rbuf_offset + + hdr.bh_hdrlen + hdr.bh_caplen); + continue; + } + + /* Skip over the BPF header... */ + interface->rbuf_offset += hdr.bh_hdrlen; + + /* Decode the physical header... */ + offset = decode_hw_header(interface, interface->rbuf, + interface->rbuf_offset, hfrom); + + /* If a physical layer checksum failed (dunno of any + physical layer that supports this, but WTH), skip this + packet. */ + if (offset < 0) { + interface->rbuf_offset = + BPF_WORDALIGN(interface->rbuf_offset + + hdr.bh_caplen); + continue; + } + interface->rbuf_offset += offset; + hdr.bh_caplen -= offset; + + /* Decode the IP and UDP headers... */ + offset = decode_udp_ip_header(interface, interface->rbuf, + interface->rbuf_offset, + from, hdr.bh_caplen, &paylen, 1); + + /* If the IP or UDP checksum was bad, skip the packet... */ + if (offset < 0) { + interface->rbuf_offset = + BPF_WORDALIGN(interface->rbuf_offset + + hdr.bh_caplen); + continue; + } + interface->rbuf_offset = interface->rbuf_offset + offset; + hdr.bh_caplen -= offset; + + /* If there's not enough room to stash the packet data, + we have to skip it (this shouldn't happen in real + life, though). */ + if (hdr.bh_caplen > len) { + interface->rbuf_offset = + BPF_WORDALIGN(interface->rbuf_offset + + hdr.bh_caplen); + continue; + } + + /* Copy out the data in the packet... */ + memcpy(buf, interface->rbuf + interface->rbuf_offset, paylen); + interface->rbuf_offset = + BPF_WORDALIGN(interface->rbuf_offset + hdr.bh_caplen); + return paylen; + } while (interface->rbuf_offset < interface->rbuf_len); + + return (0); +} + +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) { + struct ifaddrs *ifa; + struct ifaddrs *p; + struct sockaddr_dl *sa; + + if (getifaddrs(&ifa) != 0) { + log_fatal("Error getting interface information; %m"); + } + + /* + * Loop through our interfaces finding a match. + */ + sa = NULL; + for (p=ifa; (p != NULL) && (sa == NULL); p = p->ifa_next) { + if ((p->ifa_addr->sa_family == AF_LINK) && + !strcmp(p->ifa_name, name)) { + sa = (struct sockaddr_dl *)p->ifa_addr; + } + } + if (sa == NULL) { + log_fatal("No interface called '%s'", name); + } + + /* + * Pull out the appropriate information. + */ + switch (sa->sdl_type) { + case IFT_ETHER: +#if defined (IFT_L2VLAN) + case IFT_L2VLAN: +#endif + hw->hlen = sa->sdl_alen + 1; + hw->hbuf[0] = HTYPE_ETHER; + memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen); + break; + case IFT_ISO88023: + case IFT_ISO88024: /* "token ring" */ + case IFT_ISO88025: + case IFT_ISO88026: + hw->hlen = sa->sdl_alen + 1; + hw->hbuf[0] = HTYPE_IEEE802; + memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen); + break; +#ifdef IFT_FDDI + case IFT_FDDI: + hw->hlen = sa->sdl_alen + 1; + hw->hbuf[0] = HTYPE_FDDI; + memcpy(&hw->hbuf[1], LLADDR(sa), sa->sdl_alen); + break; +#endif /* IFT_FDDI */ + default: + log_fatal("Unsupported device type %d for \"%s\"", + sa->sdl_type, name); + } + + freeifaddrs(ifa); +} +#endif |