ndbootd-bpf.c revision 1.3
1 /* $NetBSD: ndbootd-bpf.c,v 1.3 2001/05/23 02:59:36 fredette 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 static const char _ndbootd_bpf_c_rcsid[] = "<<Id: ndbootd-bpf.c,v 1.4 2001/05/23 02:35:49 fredette Exp >>"; 48 49 /* includes: */ 50 #include <net/bpf.h> 51 52 /* structures: */ 53 struct _ndbootd_interface_bpf { 54 55 /* the size of the packet buffer for the interface: */ 56 size_t _ndbootd_interface_bpf_buffer_size; 57 58 /* the packet buffer for the interface: */ 59 char *_ndbootd_interface_bpf_buffer; 60 61 /* the next offset within the packet buffer, and the end of the data 62 * in the packet buffer: */ 63 size_t _ndbootd_interface_bpf_buffer_offset; 64 size_t _ndbootd_interface_bpf_buffer_end; 65 }; 66 67 /* the BPF program to capture ND packets: */ 68 static struct bpf_insn ndboot_bpf_filter[] = { 69 70 /* drop this packet if its ethertype isn't ETHERTYPE_IP: */ 71 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, NDBOOTD_OFFSETOF(struct ether_header, ether_type)), 72 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 9), 73 74 /* drop this packet if its IP protocol isn't IPPROTO_ND: */ 75 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_p)), 76 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_ND, 0, 7), 77 78 /* drop this packet if it's a fragment: */ 79 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_off)), 80 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x3fff, 5, 0), 81 82 /* drop this packet if it is carrying data (we only want requests, 83 * which have no data): */ 84 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_len)), 85 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, sizeof(struct ether_header)), 86 BPF_STMT(BPF_ALU + BPF_SUB + BPF_X, 0), 87 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ndboot_packet), 0, 1), 88 89 /* accept this packet: */ 90 BPF_STMT(BPF_RET + BPF_K, (u_int) -1), 91 92 /* drop this packet: */ 93 BPF_STMT(BPF_RET + BPF_K, 0), 94 }; 95 96 /* this opens a raw socket using BPF. */ 97 int 98 ndbootd_raw_open(struct ndbootd_interface * interface) 99 { 100 int network_fd; 101 #define DEV_BPF_FORMAT "/dev/bpf%d" 102 char dev_bpf_filename[sizeof(DEV_BPF_FORMAT) + (sizeof(int) * 3) + 1]; 103 int minor; 104 int saved_errno; 105 u_int bpf_opt; 106 struct bpf_version version; 107 u_int packet_buffer_size; 108 struct bpf_program program; 109 struct _ndbootd_interface_bpf *interface_bpf; 110 111 /* loop trying to open a /dev/bpf device: */ 112 for (minor = 0;; minor++) { 113 114 /* form the name of the next device to try, then try opening 115 * it. if we succeed, we're done: */ 116 sprintf(dev_bpf_filename, DEV_BPF_FORMAT, minor); 117 _NDBOOTD_DEBUG((fp, "bpf: trying %s", dev_bpf_filename)); 118 if ((network_fd = open(dev_bpf_filename, O_RDWR)) >= 0) { 119 _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename)); 120 break; 121 } 122 /* we failed to open this device. if this device was simply 123 * busy, loop: */ 124 _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno))); 125 if (errno == EBUSY) { 126 continue; 127 } 128 /* otherwise, we have failed: */ 129 return (-1); 130 } 131 132 /* this macro helps in closing the BPF socket on error: */ 133 #define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno 134 135 /* check the BPF version: */ 136 if (ioctl(network_fd, BIOCVERSION, &version) < 0) { 137 _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s", 138 dev_bpf_filename, strerror(errno))); 139 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 140 return (-1); 141 } 142 if (version.bv_major != BPF_MAJOR_VERSION 143 || version.bv_minor < BPF_MINOR_VERSION) { 144 _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d", 145 version.bv_major, version.bv_minor, 146 BPF_MAJOR_VERSION, BPF_MINOR_VERSION)); 147 close(network_fd); 148 errno = ENXIO; 149 return (-1); 150 } 151 /* put the BPF device into immediate mode: */ 152 bpf_opt = TRUE; 153 if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) { 154 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s", 155 dev_bpf_filename, strerror(errno))); 156 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 157 return (-1); 158 } 159 /* tell the BPF device we're providing complete Ethernet headers: */ 160 bpf_opt = TRUE; 161 if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) { 162 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s", 163 dev_bpf_filename, strerror(errno))); 164 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 165 return (-1); 166 } 167 /* point the BPF device at the interface we're using: */ 168 if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) { 169 _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s", 170 interface->ndbootd_interface_ifreq->ifr_name, strerror(errno))); 171 saved_errno = errno; 172 close(network_fd); 173 errno = saved_errno; 174 return (-1); 175 } 176 /* set the filter on the BPF device: */ 177 program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]); 178 program.bf_insns = ndboot_bpf_filter; 179 if (ioctl(network_fd, BIOCSETF, &program) < 0) { 180 _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s", 181 dev_bpf_filename, strerror(errno))); 182 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 183 return (-1); 184 } 185 /* get the BPF read buffer size: */ 186 if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) { 187 _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s", 188 dev_bpf_filename, strerror(errno))); 189 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 190 return (-1); 191 } 192 _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u", 193 dev_bpf_filename, packet_buffer_size)); 194 195 /* allocate our private interface information and we're done: */ 196 interface->ndbootd_interface_fd = network_fd; 197 interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1); 198 interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size; 199 interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size); 200 interface->_ndbootd_interface_raw_private = interface_bpf; 201 return (0); 202 #undef _NDBOOTD_RAW_OPEN_ERROR 203 } 204 205 /* this reads a raw packet: */ 206 int 207 ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 208 { 209 struct _ndbootd_interface_bpf *interface_bpf; 210 ssize_t buffer_end; 211 struct bpf_hdr the_bpf_header; 212 fd_set fdset_read; 213 214 /* recover our state: */ 215 interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private; 216 217 /* loop until we have something to return: */ 218 for (;;) { 219 220 /* if the buffer is empty, fill it: */ 221 if (interface_bpf->_ndbootd_interface_bpf_buffer_offset 222 >= interface_bpf->_ndbootd_interface_bpf_buffer_end) { 223 224 /* select on the BPF socket: */ 225 _NDBOOTD_DEBUG((fp, "bpf: calling select")); 226 FD_ZERO(&fdset_read); 227 FD_SET(interface->ndbootd_interface_fd, &fdset_read); 228 switch (select(interface->ndbootd_interface_fd + 1, &fdset_read, NULL, NULL, NULL)) { 229 case 0: 230 _NDBOOTD_DEBUG((fp, "bpf: select returned zero")); 231 continue; 232 case 1: 233 break; 234 default: 235 if (errno == EINTR) { 236 _NDBOOTD_DEBUG((fp, "bpf: select got EINTR")); 237 continue; 238 } 239 _NDBOOTD_DEBUG((fp, "bpf: select failed: %s", strerror(errno))); 240 return (-1); 241 } 242 assert(FD_ISSET(interface->ndbootd_interface_fd, &fdset_read)); 243 244 /* read the BPF socket: */ 245 _NDBOOTD_DEBUG((fp, "bpf: calling read")); 246 buffer_end = read(interface->ndbootd_interface_fd, 247 interface_bpf->_ndbootd_interface_bpf_buffer, 248 interface_bpf->_ndbootd_interface_bpf_buffer_size); 249 if (buffer_end <= 0) { 250 _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno))); 251 return (-1); 252 } 253 _NDBOOTD_DEBUG((fp, "bpf: read %ld bytes of packets", (long) buffer_end)); 254 interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0; 255 interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end; 256 } 257 /* if there's not enough for a BPF header, flush the buffer: */ 258 if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset 259 + sizeof(the_bpf_header)) 260 > interface_bpf->_ndbootd_interface_bpf_buffer_end) { 261 _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes")); 262 interface_bpf->_ndbootd_interface_bpf_buffer_end = 0; 263 continue; 264 } 265 /* get the BPF header and check it: */ 266 memcpy(&the_bpf_header, 267 interface_bpf->_ndbootd_interface_bpf_buffer 268 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 269 sizeof(the_bpf_header)); 270 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen; 271 272 /* if we're missing some part of the packet: */ 273 if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen 274 || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen) 275 > interface_bpf->_ndbootd_interface_bpf_buffer_end)) { 276 _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet")); 277 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 278 continue; 279 } 280 /* silently ignore packets that don't even have Ethernet 281 * headers, and those packets that we transmitted: */ 282 if (the_bpf_header.bh_datalen < sizeof(struct ether_header) 283 || !memcmp(((struct ether_header *) 284 (interface_bpf->_ndbootd_interface_bpf_buffer 285 + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost, 286 interface->ndbootd_interface_ether, 287 ETHER_ADDR_LEN)) { 288 /* silently ignore packets from us: */ 289 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 290 continue; 291 } 292 /* if the caller hasn't provided a large enough buffer: */ 293 if (packet_buffer_size < the_bpf_header.bh_datalen) { 294 errno = EIO; 295 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 296 return (-1); 297 } 298 /* return this captured packet to the user: */ 299 memcpy(packet_buffer, 300 interface_bpf->_ndbootd_interface_bpf_buffer 301 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 302 the_bpf_header.bh_datalen); 303 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 304 return (the_bpf_header.bh_datalen); 305 } 306 /* NOTREACHED */ 307 } 308 309 /* this writes a raw packet: */ 310 int 311 ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 312 { 313 return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size)); 314 } 315
Indexes created Tue Sep 23 07:09:52 GMT 2025