ndbootd-bpf.c revision 1.1.1.1
1 /* ndbootd-bpf.c - the Sun Network Disk (nd) daemon BPF component: */ 2 3 /* 4 * Copyright (c) 2001 Matthew Fredette. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. All advertising materials mentioning features or use of this software 15 * must display the following acknowledgement: 16 * This product includes software developed by Matthew Fredette. 17 * 4. The name of Matthew Fredette may not be used to endorse or promote 18 * products derived from this software without specific prior written 19 * permission. 20 * 21 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 22 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 24 */ 25 26 /* <<Header: /data/home/fredette/project/THE-WEIGHT-CVS/ndbootd/config/ndbootd-bpf.c,v 1.3 2001/05/22 13:13:24 fredette Exp >> */ 27 28 /* 29 * <<Log: ndbootd-bpf.c,v >> 30 * Revision 1.3 2001/05/22 13:13:24 fredette 31 * Ran indent(1) with NetBSD's KNF-approximating profile. 32 * 33 * Revision 1.2 2001/05/09 20:50:46 fredette 34 * Removed an unnecessary comment. 35 * 36 * Revision 1.1 2001/01/29 15:12:13 fredette 37 * Added. 38 * 39 */ 40 41 static const char _ndbootd_bpf_c_rcsid[] = "<<Id: ndbootd-bpf.c,v 1.3 2001/05/22 13:13:24 fredette Exp >>"; 42 43 /* includes: */ 44 #include <net/bpf.h> 45 46 /* structures: */ 47 struct _ndbootd_interface_bpf { 48 49 /* the size of the packet buffer for the interface: */ 50 size_t _ndbootd_interface_bpf_buffer_size; 51 52 /* the packet buffer for the interface: */ 53 char *_ndbootd_interface_bpf_buffer; 54 55 /* the next offset within the packet buffer, and the end of the data 56 * in the packet buffer: */ 57 size_t _ndbootd_interface_bpf_buffer_offset; 58 size_t _ndbootd_interface_bpf_buffer_end; 59 }; 60 61 /* the BPF program to capture ND packets: */ 62 static struct bpf_insn ndboot_bpf_filter[] = { 63 64 /* drop this packet if its ethertype isn't ETHERTYPE_IP: */ 65 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, NDBOOTD_OFFSETOF(struct ether_header, ether_type)), 66 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 9), 67 68 /* drop this packet if its IP protocol isn't IPPROTO_ND: */ 69 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_p)), 70 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_ND, 0, 7), 71 72 /* drop this packet if it's a fragment: */ 73 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_off)), 74 BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x3fff, 5, 0), 75 76 /* drop this packet if it is carrying data (we only want requests, 77 * which have no data): */ 78 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, sizeof(struct ether_header) + NDBOOTD_OFFSETOF(struct ip, ip_len)), 79 BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, sizeof(struct ether_header)), 80 BPF_STMT(BPF_ALU + BPF_SUB + BPF_X, 0), 81 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ndboot_packet), 0, 1), 82 83 /* accept this packet: */ 84 BPF_STMT(BPF_RET + BPF_K, (u_int) -1), 85 86 /* drop this packet: */ 87 BPF_STMT(BPF_RET + BPF_K, 0), 88 }; 89 90 /* this opens a raw socket using BPF. */ 91 int 92 ndbootd_raw_open(struct ndbootd_interface * interface) 93 { 94 int network_fd; 95 #define DEV_BPF_FORMAT "/dev/bpf%d" 96 char dev_bpf_filename[sizeof(DEV_BPF_FORMAT) + (sizeof(int) * 3) + 1]; 97 int minor; 98 int saved_errno; 99 u_int bpf_opt; 100 struct bpf_version version; 101 u_int packet_buffer_size; 102 struct bpf_program program; 103 struct _ndbootd_interface_bpf *interface_bpf; 104 105 /* loop trying to open a /dev/bpf device: */ 106 for (minor = 0;; minor++) { 107 108 /* form the name of the next device to try, then try opening 109 * it. if we succeed, we're done: */ 110 sprintf(dev_bpf_filename, DEV_BPF_FORMAT, minor); 111 _NDBOOTD_DEBUG((fp, "bpf: trying %s", dev_bpf_filename)); 112 if ((network_fd = open(dev_bpf_filename, O_RDWR)) >= 0) { 113 _NDBOOTD_DEBUG((fp, "bpf: opened %s", dev_bpf_filename)); 114 break; 115 } 116 /* we failed to open this device. if this device was simply 117 * busy, loop: */ 118 _NDBOOTD_DEBUG((fp, "bpf: failed to open %s: %s", dev_bpf_filename, strerror(errno))); 119 if (errno == EBUSY) { 120 continue; 121 } 122 /* otherwise, we have failed: */ 123 return (-1); 124 } 125 126 /* this macro helps in closing the BPF socket on error: */ 127 #define _NDBOOTD_RAW_OPEN_ERROR(x) saved_errno = errno; x; errno = saved_errno 128 129 /* check the BPF version: */ 130 if (ioctl(network_fd, BIOCVERSION, &version) < 0) { 131 _NDBOOTD_DEBUG((fp, "bpf: failed to get the BPF version on %s: %s", 132 dev_bpf_filename, strerror(errno))); 133 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 134 return (-1); 135 } 136 if (version.bv_major != BPF_MAJOR_VERSION 137 || version.bv_minor < BPF_MINOR_VERSION) { 138 _NDBOOTD_DEBUG((fp, "bpf: kernel BPF version is %d.%d, my BPF version is %d.%d", 139 version.bv_major, version.bv_minor, 140 BPF_MAJOR_VERSION, BPF_MINOR_VERSION)); 141 close(network_fd); 142 errno = ENXIO; 143 return (-1); 144 } 145 /* put the BPF device into immediate mode: */ 146 bpf_opt = TRUE; 147 if (ioctl(network_fd, BIOCIMMEDIATE, &bpf_opt) < 0) { 148 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into immediate mode: %s", 149 dev_bpf_filename, strerror(errno))); 150 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 151 return (-1); 152 } 153 /* tell the BPF device we're providing complete Ethernet headers: */ 154 bpf_opt = TRUE; 155 if (ioctl(network_fd, BIOCSHDRCMPLT, &bpf_opt) < 0) { 156 _NDBOOTD_DEBUG((fp, "bpf: failed to put %s into complete-headers mode: %s", 157 dev_bpf_filename, strerror(errno))); 158 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 159 return (-1); 160 } 161 /* point the BPF device at the interface we're using: */ 162 if (ioctl(network_fd, BIOCSETIF, interface->ndbootd_interface_ifreq) < 0) { 163 _NDBOOTD_DEBUG((fp, "bpf: failed to point BPF socket at %s: %s", 164 interface->ndbootd_interface_ifreq->ifr_name, strerror(errno))); 165 saved_errno = errno; 166 close(network_fd); 167 errno = saved_errno; 168 return (-1); 169 } 170 /* set the filter on the BPF device: */ 171 program.bf_len = sizeof(ndboot_bpf_filter) / sizeof(ndboot_bpf_filter[0]); 172 program.bf_insns = ndboot_bpf_filter; 173 if (ioctl(network_fd, BIOCSETF, &program) < 0) { 174 _NDBOOTD_DEBUG((fp, "bpf: failed to set the filter on %s: %s", 175 dev_bpf_filename, strerror(errno))); 176 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 177 return (-1); 178 } 179 /* get the BPF read buffer size: */ 180 if (ioctl(network_fd, BIOCGBLEN, &packet_buffer_size) < 0) { 181 _NDBOOTD_DEBUG((fp, "bpf: failed to read the buffer size for %s: %s", 182 dev_bpf_filename, strerror(errno))); 183 _NDBOOTD_RAW_OPEN_ERROR(close(network_fd)); 184 return (-1); 185 } 186 _NDBOOTD_DEBUG((fp, "bpf: buffer size for %s is %u", 187 dev_bpf_filename, packet_buffer_size)); 188 189 /* allocate our private interface information and we're done: */ 190 interface->ndbootd_interface_fd = network_fd; 191 interface_bpf = ndbootd_new0(struct _ndbootd_interface_bpf, 1); 192 interface_bpf->_ndbootd_interface_bpf_buffer_size = packet_buffer_size; 193 interface_bpf->_ndbootd_interface_bpf_buffer = ndbootd_new(char, packet_buffer_size); 194 interface->_ndbootd_interface_raw_private = interface_bpf; 195 return (0); 196 #undef _NDBOOTD_RAW_OPEN_ERROR 197 } 198 199 /* this reads a raw packet: */ 200 int 201 ndbootd_raw_read(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 202 { 203 struct _ndbootd_interface_bpf *interface_bpf; 204 ssize_t buffer_end; 205 struct bpf_hdr the_bpf_header; 206 fd_set fdset_read; 207 208 /* recover our state: */ 209 interface_bpf = (struct _ndbootd_interface_bpf *) interface->_ndbootd_interface_raw_private; 210 211 /* loop until we have something to return: */ 212 for (;;) { 213 214 /* if the buffer is empty, fill it: */ 215 if (interface_bpf->_ndbootd_interface_bpf_buffer_offset 216 >= interface_bpf->_ndbootd_interface_bpf_buffer_end) { 217 218 /* select on the BPF socket: */ 219 _NDBOOTD_DEBUG((fp, "bpf: calling select")); 220 FD_ZERO(&fdset_read); 221 FD_SET(interface->ndbootd_interface_fd, &fdset_read); 222 switch (select(interface->ndbootd_interface_fd + 1, &fdset_read, NULL, NULL, NULL)) { 223 case 0: 224 _NDBOOTD_DEBUG((fp, "bpf: select returned zero")); 225 continue; 226 case 1: 227 break; 228 default: 229 if (errno == EINTR) { 230 _NDBOOTD_DEBUG((fp, "bpf: select got EINTR")); 231 continue; 232 } 233 _NDBOOTD_DEBUG((fp, "bpf: select failed: %s", strerror(errno))); 234 return (-1); 235 } 236 assert(FD_ISSET(interface->ndbootd_interface_fd, &fdset_read)); 237 238 /* read the BPF socket: */ 239 _NDBOOTD_DEBUG((fp, "bpf: calling read")); 240 buffer_end = read(interface->ndbootd_interface_fd, 241 interface_bpf->_ndbootd_interface_bpf_buffer, 242 interface_bpf->_ndbootd_interface_bpf_buffer_size); 243 if (buffer_end <= 0) { 244 _NDBOOTD_DEBUG((fp, "bpf: failed to read packets: %s", strerror(errno))); 245 return (-1); 246 } 247 _NDBOOTD_DEBUG((fp, "bpf: read %d bytes of packets", buffer_end)); 248 interface_bpf->_ndbootd_interface_bpf_buffer_offset = 0; 249 interface_bpf->_ndbootd_interface_bpf_buffer_end = buffer_end; 250 } 251 /* if there's not enough for a BPF header, flush the buffer: */ 252 if ((interface_bpf->_ndbootd_interface_bpf_buffer_offset 253 + sizeof(the_bpf_header)) 254 > interface_bpf->_ndbootd_interface_bpf_buffer_end) { 255 _NDBOOTD_DEBUG((fp, "bpf: flushed garbage BPF header bytes")); 256 interface_bpf->_ndbootd_interface_bpf_buffer_end = 0; 257 continue; 258 } 259 /* get the BPF header and check it: */ 260 memcpy(&the_bpf_header, 261 interface_bpf->_ndbootd_interface_bpf_buffer 262 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 263 sizeof(the_bpf_header)); 264 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_hdrlen; 265 266 /* if we're missing some part of the packet: */ 267 if (the_bpf_header.bh_caplen != the_bpf_header.bh_datalen 268 || ((interface_bpf->_ndbootd_interface_bpf_buffer_offset + the_bpf_header.bh_datalen) 269 > interface_bpf->_ndbootd_interface_bpf_buffer_end)) { 270 _NDBOOTD_DEBUG((fp, "bpf: flushed truncated BPF packet")); 271 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 272 continue; 273 } 274 /* silently ignore packets that don't even have Ethernet 275 * headers, and those packets that we transmitted: */ 276 if (the_bpf_header.bh_datalen < sizeof(struct ether_header) 277 || !memcmp(((struct ether_header *) 278 (interface_bpf->_ndbootd_interface_bpf_buffer 279 + interface_bpf->_ndbootd_interface_bpf_buffer_offset))->ether_shost, 280 interface->ndbootd_interface_ether, 281 ETHER_ADDR_LEN)) { 282 /* silently ignore packets from us: */ 283 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 284 continue; 285 } 286 /* if the caller hasn't provided a large enough buffer: */ 287 if (packet_buffer_size < the_bpf_header.bh_datalen) { 288 errno = EIO; 289 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 290 return (-1); 291 } 292 /* return this captured packet to the user: */ 293 memcpy(packet_buffer, 294 interface_bpf->_ndbootd_interface_bpf_buffer 295 + interface_bpf->_ndbootd_interface_bpf_buffer_offset, 296 the_bpf_header.bh_datalen); 297 interface_bpf->_ndbootd_interface_bpf_buffer_offset += the_bpf_header.bh_datalen; 298 return (the_bpf_header.bh_datalen); 299 } 300 /* NOTREACHED */ 301 } 302 303 /* this writes a raw packet: */ 304 int 305 ndbootd_raw_write(struct ndbootd_interface * interface, void *packet_buffer, size_t packet_buffer_size) 306 { 307 return (write(interface->ndbootd_interface_fd, packet_buffer, packet_buffer_size)); 308 } 309
Indexes created Fri Oct 17 17:09:57 GMT 2025