ndbootd-bpf.c revision 1.6
1 /* $NetBSD: ndbootd-bpf.c,v 1.6 2003/07/15 12:32:07 itojun 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 1.6 2003/07/15 12:32:07 itojun 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 snprintf(dev_bpf_filename, sizeof(dev_bpf_filename), 123 DEV_BPF_FORMAT, minor); 124 _NDBOOTD_DEBUG((fp, "bpf: trying %s", dev_bpf_filename)); 125 if ((network_fd = open(dev_bpf_filename, O_RDWR)) >= 0) { 126 _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename)); 127 break; 128 } 129 /* we failed to open this device. if this device was simply 130 * busy, loop: */ 131 _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno))); 132 if (errno == EBUSY) { 133 continue; 134 } 135 /* otherwise, we have failed: */ 136 return (-1); 137 } 138 139 /* this macro helps in closing the BPF socket on error: */ 140 #define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno 141 142 /* check the BPF version: */ 143 if (ioctl(network_fd, BIOCVERSION, &version) < 0) { 144 _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s", 145 dev_bpf_filename, strerror(errno))); 146 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 147 return (-1); 148 } 149 if (version.bv_major != BPF_MAJOR_VERSION 150 || version.bv_minor < BPF_MINOR_VERSION) { 151 _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d", 152 version.bv_major, version.bv_minor, 153 BPF_MAJOR_VERSION, BPF_MINOR_VERSION)); 154 close(network_fd); 155 errno = ENXIO; 156 return (-1); 157 } 158 /* put the BPF device into immediate mode: */ 159 bpf_opt = TRUE; 160 if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) { 161 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s", 162 dev_bpf_filename, strerror(errno))); 163 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 164 return (-1); 165 } 166 /* tell the BPF device we're providing complete Ethernet headers: */ 167 bpf_opt = TRUE; 168 if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) { 169 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s", 170 dev_bpf_filename, strerror(errno))); 171 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 172 return (-1); 173 } 174 /* point the BPF device at the interface we're using: */ 175 if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) { 176 _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s", 177 interface->ndbootd_interface_ifreq->ifr_name, strerror(errno))); 178 saved_errno = errno; 179 close(network_fd); 180 errno = saved_errno; 181 return (-1); 182 } 183 /* set the filter on the BPF device: */ 184 program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]); 185 program.bf_insns = ndboot_bpf_filter; 186 if (ioctl(network_fd, BIOCSETF, &program) < 0) { 187 _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s", 188 dev_bpf_filename, strerror(errno))); 189 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 190 return (-1); 191 } 192 /* get the BPF read buffer size: */ 193 if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) { 194 _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s", 195 dev_bpf_filename, strerror(errno))); 196 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 197 return (-1); 198 } 199 _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u", 200 dev_bpf_filename, packet_buffer_size)); 201 202 /* allocate our private interface information and we're done: */ 203 interface->ndbootd_interface_fd = network_fd; 204 interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1); 205 interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size; 206 interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size); 207 interface->_ndbootd_interface_raw_private = interface_bpf; 208 return (0); 209 #undef _NDBOOTD_RAW_OPEN_ERROR 210 } 211 212 /* this reads a raw packet: */ 213 int 214 ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 215 { 216 struct _ndbootd_interface_bpf *interface_bpf; 217 ssize_t buffer_end; 218 struct bpf_hdr the_bpf_header; 219 struct pollfd set[1]; 220 221 /* recover our state: */ 222 interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private; 223 224 /* loop until we have something to return: */ 225 set[0].fd = interface->ndbootd_interface_fd; 226 set[0].events = POLLIN; 227 for (;;) { 228 229 /* if the buffer is empty, fill it: */ 230 if (interface_bpf->_ndbootd_interface_bpf_buffer_offset 231 >= interface_bpf->_ndbootd_interface_bpf_buffer_end) { 232 233 /* poll on the BPF socket: */ 234 _NDBOOTD_DEBUG((fp, "bpf: calling poll")); 235 switch (poll(set, 1, INFTIM)) { 236 case 0: 237 _NDBOOTD_DEBUG((fp, "bpf: poll returned zero")); 238 continue; 239 case 1: 240 break; 241 default: 242 if (errno == EINTR) { 243 _NDBOOTD_DEBUG((fp, "bpf: poll got EINTR")); 244 continue; 245 } 246 _NDBOOTD_DEBUG((fp, "bpf: poll failed: %s", strerror(errno))); 247 return (-1); 248 } 249 assert(set[0].revents & POLLIN); 250 251 /* read the BPF socket: */ 252 _NDBOOTD_DEBUG((fp, "bpf: calling read")); 253 buffer_end = read(interface->ndbootd_interface_fd, 254 interface_bpf->_ndbootd_interface_bpf_buffer, 255 interface_bpf->_ndbootd_interface_bpf_buffer_size); 256 if (buffer_end <= 0) { 257 _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno))); 258 return (-1); 259 } 260 _NDBOOTD_DEBUG((fp, "bpf: read %ld bytes of packets", (long) buffer_end)); 261 interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0; 262 interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end; 263 } 264 /* if there's not enough for a BPF header, flush the buffer: */ 265 if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset 266 + sizeof(the_bpf_header)) 267 > interface_bpf->_ndbootd_interface_bpf_buffer_end) { 268 _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes")); 269 interface_bpf->_ndbootd_interface_bpf_buffer_end = 0; 270 continue; 271 } 272 /* get the BPF header and check it: */ 273 memcpy(&the_bpf_header, 274 interface_bpf->_ndbootd_interface_bpf_buffer 275 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 276 sizeof(the_bpf_header)); 277 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen; 278 279 /* if we're missing some part of the packet: */ 280 if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen 281 || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen) 282 > interface_bpf->_ndbootd_interface_bpf_buffer_end)) { 283 _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet")); 284 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 285 continue; 286 } 287 /* silently ignore packets that don't even have Ethernet 288 * headers, and those packets that we transmitted: */ 289 if (the_bpf_header.bh_datalen < sizeof(struct ether_header) 290 || !memcmp(((struct ether_header *) 291 (interface_bpf->_ndbootd_interface_bpf_buffer 292 + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost, 293 interface->ndbootd_interface_ether, 294 ETHER_ADDR_LEN)) { 295 /* silently ignore packets from us: */ 296 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 297 continue; 298 } 299 /* if the caller hasn't provided a large enough buffer: */ 300 if (packet_buffer_size < the_bpf_header.bh_datalen) { 301 errno = EIO; 302 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 303 return (-1); 304 } 305 /* return this captured packet to the user: */ 306 memcpy(packet_buffer, 307 interface_bpf->_ndbootd_interface_bpf_buffer 308 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 309 the_bpf_header.bh_datalen); 310 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 311 return (the_bpf_header.bh_datalen); 312 } 313 /* NOTREACHED */ 314 } 315 316 /* this writes a raw packet: */ 317 int 318 ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 319 { 320 return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size)); 321 } 322
Indexes created Mon Sep 22 21:09:42 GMT 2025