1 /* $NetBSD: ndbootd-bpf.c,v 1.5 2002/09/19 16:46:00 mycroft Exp $ */ 2 3 /* ndbootd-bpf.c - the Sun Network Disk (nd) daemon BPF component: */ 4 5 /* 6 * Copyright (c) 2001 Matthew Fredette. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Matthew Fredette. 19 * 4. The name of Matthew Fredette may not be used to endorse or promote 20 * products derived from this software without specific prior written 21 * permission. 22 * 23 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 24 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 26 */ 27 28 /* <<Header: /data/home/fredette/project/THE-WEIGHT-CVS/ndbootd/config/ndbootd-bpf.c,v 1.4 2001/05/23 02:35:49 fredette Exp >> */ 29 30 /* 31 * <<Log: ndbootd-bpf.c,v >> 32 * Revision 1.4 2001/05/23 02:35:49 fredette 33 * Changed many debugging printfs to compile quietly on the 34 * alpha. Patch from Andrew Brown <atatat@atatdot.net>. 35 * 36 * Revision 1.3 2001/05/22 13:13:24 fredette 37 * Ran indent(1) with NetBSD's KNF-approximating profile. 38 * 39 * Revision 1.2 2001/05/09 20:50:46 fredette 40 * Removed an unnecessary comment. 41 * 42 * Revision 1.1 2001/01/29 15:12:13 fredette 43 * Added. 44 * 45 */ 46 47 #include <sys/cdefs.h> 48 #if o 49 static const char _ndbootd_bpf_c_rcsid[] = "<<Id: ndbootd-bpf.c,v 1.4 2001/05/23 02:35:49 fredette Exp >>"; 50 #else 51 __RCSID("$NetBSD: ndbootd-bpf.c,v 1.5 2002/09/19 16:46:00 mycroft Exp $"); 52 #endif 53 54 /* includes: */ 55 #include <sys/poll.h> 56 #include <net/bpf.h> 57 58 /* structures: */ 59 struct _ndbootd_interface_bpf { 60 61 /* the size of the packet buffer for the interface: */ 62 size_t _ndbootd_interface_bpf_buffer_size; 63 64 /* the packet buffer for the interface: */ 65 char *_ndbootd_interface_bpf_buffer; 66 67 /* the next offset within the packet buffer, and the end of the data 68 * in the packet buffer: */ 69 size_t _ndbootd_interface_bpf_buffer_offset; 70 size_t _ndbootd_interface_bpf_buffer_end; 71 }; 72 73 /* the BPF program to capture ND packets: */ 74 static struct bpf_insn ndboot_bpf_filter[] = { 75 76 /* drop this packet if its ethertype isn't ETHERTYPE_IP: */ 77 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, NDBOOTD_OFFSETOF(struct ether_header, ether_type)), 78 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 9), 79 80 /* drop this packet if its IP protocol isn't IPPROTO_ND: */ 81 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_p)), 82 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_ND, 0, 7), 83 84 /* drop this packet if it's a fragment: */ 85 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_off)), 86 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x3fff, 5, 0), 87 88 /* drop this packet if it is carrying data (we only want requests, 89 * which have no data): */ 90 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_len)), 91 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, sizeof(struct ether_header)), 92 BPF_STMT(BPF_ALU + BPF_SUB + BPF_X, 0), 93 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ndboot_packet), 0, 1), 94 95 /* accept this packet: */ 96 BPF_STMT(BPF_RET + BPF_K, (u_int) -1), 97 98 /* drop this packet: */ 99 BPF_STMT(BPF_RET + BPF_K, 0), 100 }; 101 102 /* this opens a raw socket using BPF. */ 103 int 104 ndbootd_raw_open(struct ndbootd_interface * interface) 105 { 106 int network_fd; 107 #define DEV_BPF_FORMAT "/dev/bpf%d" 108 char dev_bpf_filename[sizeof(DEV_BPF_FORMAT) + (sizeof(int) * 3) + 1]; 109 int minor; 110 int saved_errno; 111 u_int bpf_opt; 112 struct bpf_version version; 113 u_int packet_buffer_size; 114 struct bpf_program program; 115 struct _ndbootd_interface_bpf *interface_bpf; 116 117 /* loop trying to open a /dev/bpf device: */ 118 for (minor = 0;; minor++) { 119 120 /* form the name of the next device to try, then try opening 121 * it. if we succeed, we're done: */ 122 sprintf(dev_bpf_filename, DEV_BPF_FORMAT, minor); 123 _NDBOOTD_DEBUG((fp, "bpf: trying %s", dev_bpf_filename)); 124 if ((network_fd = open(dev_bpf_filename, O_RDWR)) >= 0) { 125 _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename)); 126 break; 127 } 128 /* we failed to open this device. if this device was simply 129 * busy, loop: */ 130 _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno))); 131 if (errno == EBUSY) { 132 continue; 133 } 134 /* otherwise, we have failed: */ 135 return (-1); 136 } 137 138 /* this macro helps in closing the BPF socket on error: */ 139 #define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno 140 141 /* check the BPF version: */ 142 if (ioctl(network_fd, BIOCVERSION, &version) < 0) { 143 _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s", 144 dev_bpf_filename, strerror(errno))); 145 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 146 return (-1); 147 } 148 if (version.bv_major != BPF_MAJOR_VERSION 149 || version.bv_minor < BPF_MINOR_VERSION) { 150 _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d", 151 version.bv_major, version.bv_minor, 152 BPF_MAJOR_VERSION, BPF_MINOR_VERSION)); 153 close(network_fd); 154 errno = ENXIO; 155 return (-1); 156 } 157 /* put the BPF device into immediate mode: */ 158 bpf_opt = TRUE; 159 if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) { 160 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s", 161 dev_bpf_filename, strerror(errno))); 162 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 163 return (-1); 164 } 165 /* tell the BPF device we're providing complete Ethernet headers: */ 166 bpf_opt = TRUE; 167 if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) { 168 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s", 169 dev_bpf_filename, strerror(errno))); 170 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 171 return (-1); 172 } 173 /* point the BPF device at the interface we're using: */ 174 if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) { 175 _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s", 176 interface->ndbootd_interface_ifreq->ifr_name, strerror(errno))); 177 saved_errno = errno; 178 close(network_fd); 179 errno = saved_errno; 180 return (-1); 181 } 182 /* set the filter on the BPF device: */ 183 program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]); 184 program.bf_insns = ndboot_bpf_filter; 185 if (ioctl(network_fd, BIOCSETF, &program) < 0) { 186 _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s", 187 dev_bpf_filename, strerror(errno))); 188 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 189 return (-1); 190 } 191 /* get the BPF read buffer size: */ 192 if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) { 193 _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s", 194 dev_bpf_filename, strerror(errno))); 195 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 196 return (-1); 197 } 198 _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u", 199 dev_bpf_filename, packet_buffer_size)); 200 201 /* allocate our private interface information and we're done: */ 202 interface->ndbootd_interface_fd = network_fd; 203 interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1); 204 interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size; 205 interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size); 206 interface->_ndbootd_interface_raw_private = interface_bpf; 207 return (0); 208 #undef _NDBOOTD_RAW_OPEN_ERROR 209 } 210 211 /* this reads a raw packet: */ 212 int 213 ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 214 { 215 struct _ndbootd_interface_bpf *interface_bpf; 216 ssize_t buffer_end; 217 struct bpf_hdr the_bpf_header; 218 struct pollfd set[1]; 219 220 /* recover our state: */ 221 interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private; 222 223 /* loop until we have something to return: */ 224 set[0].fd = interface->ndbootd_interface_fd; 225 set[0].events = POLLIN; 226 for (;;) { 227 228 /* if the buffer is empty, fill it: */ 229 if (interface_bpf->_ndbootd_interface_bpf_buffer_offset 230 >= interface_bpf->_ndbootd_interface_bpf_buffer_end) { 231 232 /* poll on the BPF socket: */ 233 _NDBOOTD_DEBUG((fp, "bpf: calling poll")); 234 switch (poll(set, 1, INFTIM)) { 235 case 0: 236 _NDBOOTD_DEBUG((fp, "bpf: poll returned zero")); 237 continue; 238 case 1: 239 break; 240 default: 241 if (errno == EINTR) { 242 _NDBOOTD_DEBUG((fp, "bpf: poll got EINTR")); 243 continue; 244 } 245 _NDBOOTD_DEBUG((fp, "bpf: poll failed: %s", strerror(errno))); 246 return (-1); 247 } 248 assert(set[0].revents & POLLIN); 249 250 /* read the BPF socket: */ 251 _NDBOOTD_DEBUG((fp, "bpf: calling read")); 252 buffer_end = read(interface->ndbootd_interface_fd, 253 interface_bpf->_ndbootd_interface_bpf_buffer, 254 interface_bpf->_ndbootd_interface_bpf_buffer_size); 255 if (buffer_end <= 0) { 256 _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno))); 257 return (-1); 258 } 259 _NDBOOTD_DEBUG((fp, "bpf: read %ld bytes of packets", (long) buffer_end)); 260 interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0; 261 interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end; 262 } 263 /* if there's not enough for a BPF header, flush the buffer: */ 264 if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset 265 + sizeof(the_bpf_header)) 266 > interface_bpf->_ndbootd_interface_bpf_buffer_end) { 267 _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes")); 268 interface_bpf->_ndbootd_interface_bpf_buffer_end = 0; 269 continue; 270 } 271 /* get the BPF header and check it: */ 272 memcpy(&the_bpf_header, 273 interface_bpf->_ndbootd_interface_bpf_buffer 274 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 275 sizeof(the_bpf_header)); 276 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen; 277 278 /* if we're missing some part of the packet: */ 279 if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen 280 || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen) 281 > interface_bpf->_ndbootd_interface_bpf_buffer_end)) { 282 _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet")); 283 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 284 continue; 285 } 286 /* silently ignore packets that don't even have Ethernet 287 * headers, and those packets that we transmitted: */ 288 if (the_bpf_header.bh_datalen < sizeof(struct ether_header) 289 || !memcmp(((struct ether_header *) 290 (interface_bpf->_ndbootd_interface_bpf_buffer 291 + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost, 292 interface->ndbootd_interface_ether, 293 ETHER_ADDR_LEN)) { 294 /* silently ignore packets from us: */ 295 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 296 continue; 297 } 298 /* if the caller hasn't provided a large enough buffer: */ 299 if (packet_buffer_size < the_bpf_header.bh_datalen) { 300 errno = EIO; 301 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 302 return (-1); 303 } 304 /* return this captured packet to the user: */ 305 memcpy(packet_buffer, 306 interface_bpf->_ndbootd_interface_bpf_buffer 307 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 308 the_bpf_header.bh_datalen); 309 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 310 return (the_bpf_header.bh_datalen); 311 } 312 /* NOTREACHED */ 313 } 314 315 /* this writes a raw packet: */ 316 int 317 ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 318 { 319 return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size)); 320 } 321