net/ndisc.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2013 Allied Telesis Labs NZ
   4  * Chris Packham, <judge.packham@gmail.com>
   5  *
   6  * Copyright (C) 2022 YADRO
   7  * Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
   8  */
   9
  10 /* Neighbour Discovery for IPv6 */
  11
  12 #include <common.h>
  13 #include <net.h>
  14 #include <net6.h>
  15 #include <ndisc.h>
  16 #include <stdlib.h>
  17 #include <linux/delay.h>
  18
  19 /* IPv6 destination address of packet waiting for ND */
  20 struct in6_addr net_nd_sol_packet_ip6 = ZERO_IPV6_ADDR;
  21 /* IPv6 address we are expecting ND advert from */
  22 static struct in6_addr net_nd_rep_packet_ip6 = ZERO_IPV6_ADDR;
  23 /* MAC destination address of packet waiting for ND */
  24 uchar *net_nd_packet_mac;
  25 /* pointer to packet waiting to be transmitted after ND is resolved */
  26 uchar *net_nd_tx_packet;
  27 static uchar net_nd_packet_buf[PKTSIZE_ALIGN + PKTALIGN];
  28 /* size of packet waiting to be transmitted */
  29 int net_nd_tx_packet_size;
  30 /* the timer for ND resolution */
  31 ulong net_nd_timer_start;
  32 /* the number of requests we have sent so far */
  33 int net_nd_try;
  34 struct in6_addr all_routers = ALL_ROUTERS_MULT_ADDR;
  35
  36 #define MAX_RTR_SOLICITATIONS           3
  37 /* The maximum time to delay sending the first router solicitation message. */
  38 #define MAX_SOLICITATION_DELAY          1 // 1 second
  39 /* The time to wait before sending the next router solicitation message. */
  40 #define RTR_SOLICITATION_INTERVAL       4000 // 4 seconds
  41
  42 #define IP6_NDISC_OPT_SPACE(len) (((len) + 2 + 7) & ~7)
  43
  44 /**
  45  * ndisc_insert_option() - Insert an option into a neighbor discovery packet
  46  *
  47  * @opt:        pointer to the option element of the neighbor discovery packet
  48  * @type:       option type to insert
  49  * @data:       option data to insert
  50  * @len:        data length
  51  * Return: the number of bytes inserted (which may be >= len)
  52  */
  53 static int ndisc_insert_option(__u8 *opt, int type, u8 *data, int len)
  54 {
  55         int space = IP6_NDISC_OPT_SPACE(len);
  56
  57         opt[0] = type;
  58         opt[1] = space >> 3;
  59         memcpy(&opt[2], data, len);
  60         len += 2;
  61
  62         /* fill the remainder with 0 */
  63         if (space - len > 0)
  64                 memset(&opt[len], '\0', space - len);
  65
  66         return space;
  67 }
  68
  69 /**
  70  * ndisc_extract_enetaddr() - Extract the Ethernet address from a ND packet
  71  *
  72  * Note that the link layer address could be anything but the only networking
  73  * media that u-boot supports is Ethernet so we assume we're extracting a 6
  74  * byte Ethernet MAC address.
  75  *
  76  * @ndisc:      pointer to ND packet
  77  * @enetaddr:   extracted MAC addr
  78  */
  79 static void ndisc_extract_enetaddr(struct nd_msg *ndisc, uchar enetaddr[6])
  80 {
  81         memcpy(enetaddr, &ndisc->opt[2], 6);
  82 }
  83
  84 /**
  85  * ndisc_has_option() - Check if the ND packet has the specified option set
  86  *
  87  * @ip6:        pointer to IPv6 header
  88  * @type:       option type to check
  89  * Return: 1 if ND has that option, 0 therwise
  90  */
  91 static int ndisc_has_option(struct ip6_hdr *ip6, __u8 type)
  92 {
  93         struct nd_msg *ndisc = (struct nd_msg *)(((uchar *)ip6) + IP6_HDR_SIZE);
  94
  95         if (ip6->payload_len <= sizeof(struct icmp6hdr))
  96                 return 0;
  97
  98         return ndisc->opt[0] == type;
  99 }
 100
 101 static void ip6_send_ns(struct in6_addr *neigh_addr)
 102 {
 103         struct in6_addr dst_adr;
 104         unsigned char enetaddr[6];
 105         struct nd_msg *msg;
 106         __u16 len;
 107         uchar *pkt;
 108         unsigned short csum;
 109         unsigned int pcsum;
 110
 111         debug("sending neighbor solicitation for %pI6c our address %pI6c\n",
 112               neigh_addr, &net_link_local_ip6);
 113
 114         /* calculate src, dest IPv6 addr and dest Eth addr */
 115         ip6_make_snma(&dst_adr, neigh_addr);
 116         ip6_make_mult_ethdstaddr(enetaddr, &dst_adr);
 117         len = sizeof(struct icmp6hdr) + IN6ADDRSZ +
 118             IP6_NDISC_OPT_SPACE(INETHADDRSZ);
 119
 120         pkt = (uchar *)net_tx_packet;
 121         pkt += net_set_ether(pkt, enetaddr, PROT_IP6);
 122         pkt += ip6_add_hdr(pkt, &net_link_local_ip6, &dst_adr, PROT_ICMPV6,
 123                            IPV6_NDISC_HOPLIMIT, len);
 124
 125         /* ICMPv6 - NS */
 126         msg = (struct nd_msg *)pkt;
 127         msg->icmph.icmp6_type = IPV6_NDISC_NEIGHBOUR_SOLICITATION;
 128         msg->icmph.icmp6_code = 0;
 129         memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16));
 130         memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32));
 131
 132         /* Set the target address and llsaddr option */
 133         net_copy_ip6(&msg->target, neigh_addr);
 134         ndisc_insert_option(msg->opt, ND_OPT_SOURCE_LL_ADDR, net_ethaddr,
 135                             INETHADDRSZ);
 136
 137         /* checksum */
 138         pcsum = csum_partial((__u8 *)msg, len, 0);
 139         csum = csum_ipv6_magic(&net_link_local_ip6, &dst_adr,
 140                                len, PROT_ICMPV6, pcsum);
 141         msg->icmph.icmp6_cksum = csum;
 142         pkt += len;
 143
 144         /* send it! */
 145         net_send_packet(net_tx_packet, (pkt - net_tx_packet));
 146 }
 147
 148 /*
 149  * ip6_send_rs() - Send IPv6 Router Solicitation Message.
 150  *
 151  * A router solicitation is sent to discover a router. RS message creation is
 152  * based on RFC 4861 section 4.1. Router Solicitation Message Format.
 153  */
 154 void ip6_send_rs(void)
 155 {
 156         unsigned char enetaddr[6];
 157         struct rs_msg *msg;
 158         __u16 icmp_len;
 159         uchar *pkt;
 160         unsigned short csum;
 161         unsigned int pcsum;
 162         static unsigned int retry_count;
 163
 164         if (!ip6_is_unspecified_addr(&net_gateway6) &&
 165             net_prefix_length != 0) {
 166                 net_set_state(NETLOOP_SUCCESS);
 167                 return;
 168         } else if (retry_count >= MAX_RTR_SOLICITATIONS) {
 169                 net_set_state(NETLOOP_FAIL);
 170                 net_set_timeout_handler(0, NULL);
 171                 retry_count = 0;
 172                 return;
 173         }
 174
 175         printf("ROUTER SOLICITATION %d\n", retry_count + 1);
 176
 177         ip6_make_mult_ethdstaddr(enetaddr, &all_routers);
 178         /*
 179          * ICMP length is the size of ICMP header (8) + one option (8) = 16.
 180          * The option is 2 bytes of type and length + 6 bytes for MAC.
 181          */
 182         icmp_len = sizeof(struct icmp6hdr) + IP6_NDISC_OPT_SPACE(INETHADDRSZ);
 183
 184         pkt = (uchar *)net_tx_packet;
 185         pkt += net_set_ether(pkt, enetaddr, PROT_IP6);
 186         pkt += ip6_add_hdr(pkt, &net_link_local_ip6, &all_routers, PROT_ICMPV6,
 187                            IPV6_NDISC_HOPLIMIT, icmp_len);
 188
 189         /* ICMPv6 - RS */
 190         msg = (struct rs_msg *)pkt;
 191         msg->icmph.icmp6_type = IPV6_NDISC_ROUTER_SOLICITATION;
 192         msg->icmph.icmp6_code = 0;
 193         memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16));
 194         memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32));
 195
 196         /* Set the llsaddr option */
 197         ndisc_insert_option(msg->opt, ND_OPT_SOURCE_LL_ADDR, net_ethaddr,
 198                             INETHADDRSZ);
 199
 200         /* checksum */
 201         pcsum = csum_partial((__u8 *)msg, icmp_len, 0);
 202         csum = csum_ipv6_magic(&net_link_local_ip6, &all_routers,
 203                                icmp_len, PROT_ICMPV6, pcsum);
 204         msg->icmph.icmp6_cksum = csum;
 205         pkt += icmp_len;
 206
 207         /* Wait up to 1 second if it is the first try to get the RA */
 208         if (retry_count == 0)
 209                 udelay(((unsigned int)rand() % 1000000) * MAX_SOLICITATION_DELAY);
 210
 211         /* send it! */
 212         net_send_packet(net_tx_packet, (pkt - net_tx_packet));
 213
 214         retry_count++;
 215         net_set_timeout_handler(RTR_SOLICITATION_INTERVAL, ip6_send_rs);
 216 }
 217
 218 static void
 219 ip6_send_na(uchar *eth_dst_addr, struct in6_addr *neigh_addr,
 220             struct in6_addr *target)
 221 {
 222         struct nd_msg *msg;
 223         __u16 len;
 224         uchar *pkt;
 225         unsigned short csum;
 226
 227         debug("sending neighbor advertisement for %pI6c to %pI6c (%pM)\n",
 228               target, neigh_addr, eth_dst_addr);
 229
 230         len = sizeof(struct icmp6hdr) + IN6ADDRSZ +
 231             IP6_NDISC_OPT_SPACE(INETHADDRSZ);
 232
 233         pkt = (uchar *)net_tx_packet;
 234         pkt += net_set_ether(pkt, eth_dst_addr, PROT_IP6);
 235         pkt += ip6_add_hdr(pkt, &net_link_local_ip6, neigh_addr,
 236                            PROT_ICMPV6, IPV6_NDISC_HOPLIMIT, len);
 237
 238         /* ICMPv6 - NA */
 239         msg = (struct nd_msg *)pkt;
 240         msg->icmph.icmp6_type = IPV6_NDISC_NEIGHBOUR_ADVERTISEMENT;
 241         msg->icmph.icmp6_code = 0;
 242         memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16));
 243         memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32));
 244         msg->icmph.icmp6_dataun.u_nd_advt.solicited = 1;
 245         msg->icmph.icmp6_dataun.u_nd_advt.override = 1;
 246         /* Set the target address and lltargetaddr option */
 247         net_copy_ip6(&msg->target, target);
 248         ndisc_insert_option(msg->opt, ND_OPT_TARGET_LL_ADDR, net_ethaddr,
 249                             INETHADDRSZ);
 250
 251         /* checksum */
 252         csum = csum_ipv6_magic(&net_link_local_ip6,
 253                                neigh_addr, len, PROT_ICMPV6,
 254                                csum_partial((__u8 *)msg, len, 0));
 255         msg->icmph.icmp6_cksum = csum;
 256         pkt += len;
 257
 258         /* send it! */
 259         net_send_packet(net_tx_packet, (pkt - net_tx_packet));
 260 }
 261
 262 void ndisc_request(void)
 263 {
 264         if (!ip6_addr_in_subnet(&net_ip6, &net_nd_sol_packet_ip6,
 265                                 net_prefix_length)) {
 266                 if (ip6_is_unspecified_addr(&net_gateway6)) {
 267                         puts("## Warning: gatewayip6 is needed but not set\n");
 268                         net_nd_rep_packet_ip6 = net_nd_sol_packet_ip6;
 269                 } else {
 270                         net_nd_rep_packet_ip6 = net_gateway6;
 271                 }
 272         } else {
 273                 net_nd_rep_packet_ip6 = net_nd_sol_packet_ip6;
 274         }
 275
 276         ip6_send_ns(&net_nd_rep_packet_ip6);
 277 }
 278
 279 int ndisc_timeout_check(void)
 280 {
 281         ulong t;
 282
 283         if (ip6_is_unspecified_addr(&net_nd_sol_packet_ip6))
 284                 return 0;
 285
 286         t = get_timer(0);
 287
 288         /* check for NDISC timeout */
 289         if ((t - net_nd_timer_start) > NDISC_TIMEOUT) {
 290                 net_nd_try++;
 291                 if (net_nd_try >= NDISC_TIMEOUT_COUNT) {
 292                         puts("\nNeighbour discovery retry count exceeded; "
 293                              "starting again\n");
 294                         net_nd_try = 0;
 295                         net_set_state(NETLOOP_FAIL);
 296                 } else {
 297                         net_nd_timer_start = t;
 298                         ndisc_request();
 299                 }
 300         }
 301         return 1;
 302 }
 303
 304 /*
 305  * ndisc_init() - Make initial steps for ND state machine.
 306  * Usually move variables into initial state.
 307  */
 308 void ndisc_init(void)
 309 {
 310         net_nd_packet_mac = NULL;
 311         net_nd_tx_packet = NULL;
 312         net_nd_sol_packet_ip6 = net_null_addr_ip6;
 313         net_nd_rep_packet_ip6 = net_null_addr_ip6;
 314         net_nd_tx_packet_size = 0;
 315         net_nd_tx_packet = &net_nd_packet_buf[0] + (PKTALIGN - 1);
 316         net_nd_tx_packet -= (ulong)net_nd_tx_packet % PKTALIGN;
 317 }
 318
 319 /*
 320  * validate_ra() - Validate the router advertisement message.
 321  *
 322  * @ip6: Pointer to the router advertisement packet
 323  *
 324  * Check if the router advertisement message is valid. Conditions are
 325  * according to RFC 4861 section 6.1.2. Validation of Router Advertisement
 326  * Messages.
 327  *
 328  * Return: true if the message is valid and false if it is invalid.
 329  */
 330 bool validate_ra(struct ip6_hdr *ip6)
 331 {
 332         struct icmp6hdr *icmp = (struct icmp6hdr *)(ip6 + 1);
 333
 334         /* ICMP length (derived from the IP length) should be 16 or more octets. */
 335         if (ip6->payload_len < 16)
 336                 return false;
 337
 338         /* Source IP Address should be a valid link-local address. */
 339         if ((ntohs(ip6->saddr.s6_addr16[0]) & IPV6_LINK_LOCAL_MASK) !=
 340             IPV6_LINK_LOCAL_PREFIX)
 341                 return false;
 342
 343         /*
 344          * The IP Hop Limit field should have a value of 255, i.e., the packet
 345          * could not possibly have been forwarded by a router.
 346          */
 347         if (ip6->hop_limit != 255)
 348                 return false;
 349
 350         /* ICMP checksum has already been checked in net_ip6_handler. */
 351
 352         if (icmp->icmp6_code != 0)
 353                 return false;
 354
 355         return true;
 356 }
 357
 358 /*
 359  * process_ra() - Process the router advertisement packet.
 360  *
 361  * @ip6: Pointer to the router advertisement packet
 362  * @len: Length of the router advertisement packet
 363  *
 364  * Process the received router advertisement message.
 365  * Although RFC 4861 requires retaining at least two router addresses, we only
 366  * keep one because of the U-Boot limitations and its goal of lightweight code.
 367  *
 368  * Return: 0 - RA is a default router and contains valid prefix information.
 369  * Non-zero - RA options are invalid or do not indicate it is a default router
 370  * or do not contain valid prefix information.
 371  */
 372 int process_ra(struct ip6_hdr *ip6, int len)
 373 {
 374         /* Pointer to the ICMP section of the packet */
 375         struct icmp6hdr *icmp = (struct icmp6hdr *)(ip6 + 1);
 376         struct ra_msg *msg = (struct ra_msg *)icmp;
 377         int remaining_option_len = len - IP6_HDR_SIZE - sizeof(struct ra_msg);
 378         unsigned short int option_len;  /* Length of each option */
 379         /* Pointer to the ICMPv6 message options */
 380         unsigned char *option = NULL;
 381         /* 8-bit identifier of the type of ICMPv6 option */
 382         unsigned char type = 0;
 383         struct icmp6_ra_prefix_info *prefix = NULL;
 384
 385         if (len > ETH_MAX_MTU)
 386                 return -EMSGSIZE;
 387         /* Ignore the packet if router lifetime is 0. */
 388         if (!icmp->icmp6_rt_lifetime)
 389                 return -EOPNOTSUPP;
 390
 391         /* Processing the options */
 392         option = msg->opt;
 393         while (remaining_option_len > 0) {
 394                 /* The 2nd byte of the option is its length. */
 395                 option_len = option[1];
 396                 /* All included options should have a positive length. */
 397                 if (option_len == 0)
 398                         return -EINVAL;
 399
 400                 type = option[0];
 401                 /* All option types except Prefix Information are ignored. */
 402                 switch (type) {
 403                 case ND_OPT_SOURCE_LL_ADDR:
 404                 case ND_OPT_TARGET_LL_ADDR:
 405                 case ND_OPT_REDIRECT_HDR:
 406                 case ND_OPT_MTU:
 407                         break;
 408                 case ND_OPT_PREFIX_INFO:
 409                         prefix = (struct icmp6_ra_prefix_info *)option;
 410                         /* The link-local prefix 0xfe80::/10 is ignored. */
 411                         if ((ntohs(prefix->prefix.s6_addr16[0]) &
 412                              IPV6_LINK_LOCAL_MASK) == IPV6_LINK_LOCAL_PREFIX)
 413                                 break;
 414                         if (prefix->on_link && ntohl(prefix->valid_lifetime)) {
 415                                 net_prefix_length = prefix->prefix_len;
 416                                 net_gateway6 = ip6->saddr;
 417                                 return 0;
 418                         }
 419                         break;
 420                 default:
 421                         debug("Unknown IPv6 Neighbor Discovery Option 0x%x\n",
 422                               type);
 423                 }
 424
 425                 option_len <<= 3; /* Option length is a multiple of 8. */
 426                 remaining_option_len -= option_len;
 427                 option += option_len;
 428         }
 429
 430         return -EADDRNOTAVAIL;
 431 }
 432
 433 int ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len)
 434 {
 435         struct icmp6hdr *icmp =
 436             (struct icmp6hdr *)(((uchar *)ip6) + IP6_HDR_SIZE);
 437         struct nd_msg *ndisc = (struct nd_msg *)icmp;
 438         uchar neigh_eth_addr[6];
 439         int err = 0;    // The error code returned calling functions.
 440
 441         switch (icmp->icmp6_type) {
 442         case IPV6_NDISC_NEIGHBOUR_SOLICITATION:
 443                 debug("received neighbor solicitation for %pI6c from %pI6c\n",
 444                       &ndisc->target, &ip6->saddr);
 445                 if (ip6_is_our_addr(&ndisc->target) &&
 446                     ndisc_has_option(ip6, ND_OPT_SOURCE_LL_ADDR)) {
 447                         ndisc_extract_enetaddr(ndisc, neigh_eth_addr);
 448                         ip6_send_na(neigh_eth_addr, &ip6->saddr,
 449                                     &ndisc->target);
 450                 }
 451                 break;
 452
 453         case IPV6_NDISC_NEIGHBOUR_ADVERTISEMENT:
 454                 /* are we waiting for a reply ? */
 455                 if (ip6_is_unspecified_addr(&net_nd_sol_packet_ip6))
 456                         break;
 457
 458                 if ((memcmp(&ndisc->target, &net_nd_rep_packet_ip6,
 459                             sizeof(struct in6_addr)) == 0) &&
 460                     ndisc_has_option(ip6, ND_OPT_TARGET_LL_ADDR)) {
 461                         ndisc_extract_enetaddr(ndisc, neigh_eth_addr);
 462
 463                         /* save address for later use */
 464                         if (!net_nd_packet_mac)
 465                                 net_nd_packet_mac = neigh_eth_addr;
 466
 467                         /* modify header, and transmit it */
 468                         memcpy(((struct ethernet_hdr *)net_nd_tx_packet)->et_dest,
 469                                neigh_eth_addr, 6);
 470
 471                         net_send_packet(net_nd_tx_packet,
 472                                         net_nd_tx_packet_size);
 473
 474                         /* no ND request pending now */
 475                         net_nd_sol_packet_ip6 = net_null_addr_ip6;
 476                         net_nd_tx_packet_size = 0;
 477                         net_nd_packet_mac = NULL;
 478                 }
 479                 break;
 480         case IPV6_NDISC_ROUTER_SOLICITATION:
 481                 break;
 482         case IPV6_NDISC_ROUTER_ADVERTISEMENT:
 483                 debug("Received router advertisement for %pI6c from %pI6c\n",
 484                       &ip6->daddr, &ip6->saddr);
 485                 /*
 486                  * If gateway and prefix are set, the RA packet is ignored. The
 487                  * reason is that the U-Boot code is supposed to be as compact
 488                  * as possible and does not need to take care of multiple
 489                  * routers. In addition to that, U-Boot does not want to handle
 490                  * scenarios like a router setting its lifetime to zero to
 491                  * indicate it is not routing anymore. U-Boot program has a
 492                  * short life when the system boots up and does not need such
 493                  * sophistication.
 494                  */
 495                 if (!ip6_is_unspecified_addr(&net_gateway6) &&
 496                     net_prefix_length != 0) {
 497                         break;
 498                 }
 499                 if (!validate_ra(ip6)) {
 500                         debug("Invalid router advertisement message.\n");
 501                         break;
 502                 }
 503                 err = process_ra(ip6, len);
 504                 if (err)
 505                         debug("Ignored router advertisement. Error: %d\n", err);
 506                 else
 507                         printf("Set gatewayip6: %pI6c, prefix_length: %d\n",
 508                                &net_gateway6, net_prefix_length);
 509                 break;
 510         default:
 511                 debug("Unexpected ICMPv6 type 0x%x\n", icmp->icmp6_type);
 512                 return -1;
 513         }
 514
 515         return 0;
 516 }