ndbootd-bpf.c revision 1.7
1 /* $NetBSD: ndbootd-bpf.c,v 1.7 2004/04/10 17:53:05 darrenr 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 (at) 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 1.7 2004/04/10 17:53:05 darrenr 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 bufsize; 112 u_int bpf_opt; 113 struct bpf_version version; 114 u_int packet_buffer_size; 115 struct bpf_program program; 116 struct _ndbootd_interface_bpf *interface_bpf; 117 118 /* loop trying to open a /dev/bpf device: */ 119 for (minor = 0;; minor++) { 120 121 /* form the name of the next device to try, then try opening 122 * it. if we succeed, we're done: */ 123 snprintf(dev_bpf_filename, sizeof(dev_bpf_filename), 124 DEV_BPF_FORMAT, minor); 125 _NDBOOTD_DEBUG((fp, "bpf: trying %s", dev_bpf_filename)); 126 if ((network_fd = open(dev_bpf_filename, O_RDWR)) >= 0) { 127 _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename)); 128 break; 129 } 130 /* we failed to open this device. if this device was simply 131 * busy, loop: */ 132 _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno))); 133 if (errno == EBUSY) { 134 continue; 135 } 136 /* otherwise, we have failed: */ 137 return (-1); 138 } 139 140 /* this macro helps in closing the BPF socket on error: */ 141 #define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno 142 143 /* check the BPF version: */ 144 if (ioctl(network_fd, BIOCVERSION, &version) < 0) { 145 _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s", 146 dev_bpf_filename, strerror(errno))); 147 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 148 return (-1); 149 } 150 if (version.bv_major != BPF_MAJOR_VERSION 151 || version.bv_minor < BPF_MINOR_VERSION) { 152 _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d", 153 version.bv_major, version.bv_minor, 154 BPF_MAJOR_VERSION, BPF_MINOR_VERSION)); 155 close(network_fd); 156 errno = ENXIO; 157 return (-1); 158 } 159 /* put the BPF device into immediate mode: */ 160 bpf_opt = TRUE; 161 if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) { 162 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s", 163 dev_bpf_filename, strerror(errno))); 164 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 165 return (-1); 166 } 167 /* set a reasonable sized buffer for the BPF device */ 168 bufsize = 32768; 169 if (ioctl(network_fd, BIOCSBLEN, &bufsize) < 0) { 170 _NDBOOTD_DEBUG((fp, "bpf: failed set buffer size to %d: %s", 171 bufsize, strerror(errno))); 172 } 173 /* tell the BPF device we're providing complete Ethernet headers: */ 174 bpf_opt = TRUE; 175 if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) { 176 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s", 177 dev_bpf_filename, strerror(errno))); 178 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 179 return (-1); 180 } 181 /* point the BPF device at the interface we're using: */ 182 if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) { 183 _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s", 184 interface->ndbootd_interface_ifreq->ifr_name, strerror(errno))); 185 saved_errno = errno; 186 close(network_fd); 187 errno = saved_errno; 188 return (-1); 189 } 190 /* set the filter on the BPF device: */ 191 program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]); 192 program.bf_insns = ndboot_bpf_filter; 193 if (ioctl(network_fd, BIOCSETF, &program) < 0) { 194 _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s", 195 dev_bpf_filename, strerror(errno))); 196 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 197 return (-1); 198 } 199 /* get the BPF read buffer size: */ 200 if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) { 201 _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s", 202 dev_bpf_filename, strerror(errno))); 203 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 204 return (-1); 205 } 206 _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u", 207 dev_bpf_filename, packet_buffer_size)); 208 209 /* allocate our private interface information and we're done: */ 210 interface->ndbootd_interface_fd = network_fd; 211 interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1); 212 interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size; 213 interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size); 214 interface->_ndbootd_interface_raw_private = interface_bpf; 215 return (0); 216 #undef _NDBOOTD_RAW_OPEN_ERROR 217 } 218 219 /* this reads a raw packet: */ 220 int 221 ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 222 { 223 struct _ndbootd_interface_bpf *interface_bpf; 224 ssize_t buffer_end; 225 struct bpf_hdr the_bpf_header; 226 struct pollfd set[1]; 227 228 /* recover our state: */ 229 interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private; 230 231 /* loop until we have something to return: */ 232 set[0].fd = interface->ndbootd_interface_fd; 233 set[0].events = POLLIN; 234 for (;;) { 235 236 /* if the buffer is empty, fill it: */ 237 if (interface_bpf->_ndbootd_interface_bpf_buffer_offset 238 >= interface_bpf->_ndbootd_interface_bpf_buffer_end) { 239 240 /* poll on the BPF socket: */ 241 _NDBOOTD_DEBUG((fp, "bpf: calling poll")); 242 switch (poll(set, 1, INFTIM)) { 243 case 0: 244 _NDBOOTD_DEBUG((fp, "bpf: poll returned zero")); 245 continue; 246 case 1: 247 break; 248 default: 249 if (errno == EINTR) { 250 _NDBOOTD_DEBUG((fp, "bpf: poll got EINTR")); 251 continue; 252 } 253 _NDBOOTD_DEBUG((fp, "bpf: poll failed: %s", strerror(errno))); 254 return (-1); 255 } 256 assert(set[0].revents & POLLIN); 257 258 /* read the BPF socket: */ 259 _NDBOOTD_DEBUG((fp, "bpf: calling read")); 260 buffer_end = read(interface->ndbootd_interface_fd, 261 interface_bpf->_ndbootd_interface_bpf_buffer, 262 interface_bpf->_ndbootd_interface_bpf_buffer_size); 263 if (buffer_end <= 0) { 264 _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno))); 265 return (-1); 266 } 267 _NDBOOTD_DEBUG((fp, "bpf: read %ld bytes of packets", (long) buffer_end)); 268 interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0; 269 interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end; 270 } 271 /* if there's not enough for a BPF header, flush the buffer: */ 272 if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset 273 + sizeof(the_bpf_header)) 274 > interface_bpf->_ndbootd_interface_bpf_buffer_end) { 275 _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes")); 276 interface_bpf->_ndbootd_interface_bpf_buffer_end = 0; 277 continue; 278 } 279 /* get the BPF header and check it: */ 280 memcpy(&the_bpf_header, 281 interface_bpf->_ndbootd_interface_bpf_buffer 282 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 283 sizeof(the_bpf_header)); 284 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen; 285 286 /* if we're missing some part of the packet: */ 287 if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen 288 || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen) 289 > interface_bpf->_ndbootd_interface_bpf_buffer_end)) { 290 _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet")); 291 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 292 continue; 293 } 294 /* silently ignore packets that don't even have Ethernet 295 * headers, and those packets that we transmitted: */ 296 if (the_bpf_header.bh_datalen < sizeof(struct ether_header) 297 || !memcmp(((struct ether_header *) 298 (interface_bpf->_ndbootd_interface_bpf_buffer 299 + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost, 300 interface->ndbootd_interface_ether, 301 ETHER_ADDR_LEN)) { 302 /* silently ignore packets from us: */ 303 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 304 continue; 305 } 306 /* if the caller hasn't provided a large enough buffer: */ 307 if (packet_buffer_size < the_bpf_header.bh_datalen) { 308 errno = EIO; 309 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 310 return (-1); 311 } 312 /* return this captured packet to the user: */ 313 memcpy(packet_buffer, 314 interface_bpf->_ndbootd_interface_bpf_buffer 315 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 316 the_bpf_header.bh_datalen); 317 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 318 return (the_bpf_header.bh_datalen); 319 } 320 /* NOTREACHED */ 321 } 322 323 /* this writes a raw packet: */ 324 int 325 ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 326 { 327 return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size)); 328 } 329
Indexes created Mon Sep 22 21:09:42 GMT 2025