diff options
Diffstat (limited to 'net/ndisc.c')
| -rw-r--r-- | net/ndisc.c | 515 |
1 files changed, 515 insertions, 0 deletions
diff --git a/net/ndisc.c b/net/ndisc.c new file mode 100644 index 00000000000..d417c5987ac --- /dev/null +++ b/net/ndisc.c @@ -0,0 +1,515 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2013 Allied Telesis Labs NZ + * Chris Packham, <judge.packham@gmail.com> + * + * Copyright (C) 2022 YADRO + * Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com> + */ + +/* Neighbour Discovery for IPv6 */ + +#include <net.h> +#include <net6.h> +#include <ndisc.h> +#include <stdlib.h> +#include <linux/delay.h> + +/* IPv6 destination address of packet waiting for ND */ +struct in6_addr net_nd_sol_packet_ip6 = ZERO_IPV6_ADDR; +/* IPv6 address we are expecting ND advert from */ +static struct in6_addr net_nd_rep_packet_ip6 = ZERO_IPV6_ADDR; +/* MAC destination address of packet waiting for ND */ +uchar *net_nd_packet_mac; +/* pointer to packet waiting to be transmitted after ND is resolved */ +uchar *net_nd_tx_packet; +static uchar net_nd_packet_buf[PKTSIZE_ALIGN + PKTALIGN]; +/* size of packet waiting to be transmitted */ +int net_nd_tx_packet_size; +/* the timer for ND resolution */ +ulong net_nd_timer_start; +/* the number of requests we have sent so far */ +int net_nd_try; +struct in6_addr all_routers = ALL_ROUTERS_MULT_ADDR; + +#define MAX_RTR_SOLICITATIONS 3 +/* The maximum time to delay sending the first router solicitation message. */ +#define MAX_SOLICITATION_DELAY 1 // 1 second +/* The time to wait before sending the next router solicitation message. */ +#define RTR_SOLICITATION_INTERVAL 4000 // 4 seconds + +#define IP6_NDISC_OPT_SPACE(len) (((len) + 2 + 7) & ~7) + +/** + * ndisc_insert_option() - Insert an option into a neighbor discovery packet + * + * @opt: pointer to the option element of the neighbor discovery packet + * @type: option type to insert + * @data: option data to insert + * @len: data length + * Return: the number of bytes inserted (which may be >= len) + */ +static int ndisc_insert_option(__u8 *opt, int type, u8 *data, int len) +{ + int space = IP6_NDISC_OPT_SPACE(len); + + opt[0] = type; + opt[1] = space >> 3; + memcpy(&opt[2], data, len); + len += 2; + + /* fill the remainder with 0 */ + if (space - len > 0) + memset(&opt[len], '\0', space - len); + + return space; +} + +/** + * ndisc_extract_enetaddr() - Extract the Ethernet address from a ND packet + * + * Note that the link layer address could be anything but the only networking + * media that u-boot supports is Ethernet so we assume we're extracting a 6 + * byte Ethernet MAC address. + * + * @ndisc: pointer to ND packet + * @enetaddr: extracted MAC addr + */ +static void ndisc_extract_enetaddr(struct nd_msg *ndisc, uchar enetaddr[6]) +{ + memcpy(enetaddr, &ndisc->opt[2], 6); +} + +/** + * ndisc_has_option() - Check if the ND packet has the specified option set + * + * @ip6: pointer to IPv6 header + * @type: option type to check + * Return: 1 if ND has that option, 0 therwise + */ +static int ndisc_has_option(struct ip6_hdr *ip6, __u8 type) +{ + struct nd_msg *ndisc = (struct nd_msg *)(((uchar *)ip6) + IP6_HDR_SIZE); + + if (ip6->payload_len <= sizeof(struct icmp6hdr)) + return 0; + + return ndisc->opt[0] == type; +} + +static void ip6_send_ns(struct in6_addr *neigh_addr) +{ + struct in6_addr dst_adr; + unsigned char enetaddr[6]; + struct nd_msg *msg; + __u16 len; + uchar *pkt; + unsigned short csum; + unsigned int pcsum; + + debug("sending neighbor solicitation for %pI6c our address %pI6c\n", + neigh_addr, &net_link_local_ip6); + + /* calculate src, dest IPv6 addr and dest Eth addr */ + ip6_make_snma(&dst_adr, neigh_addr); + ip6_make_mult_ethdstaddr(enetaddr, &dst_adr); + len = sizeof(struct icmp6hdr) + IN6ADDRSZ + + IP6_NDISC_OPT_SPACE(INETHADDRSZ); + + pkt = (uchar *)net_tx_packet; + pkt += net_set_ether(pkt, enetaddr, PROT_IP6); + pkt += ip6_add_hdr(pkt, &net_link_local_ip6, &dst_adr, PROT_ICMPV6, + IPV6_NDISC_HOPLIMIT, len); + + /* ICMPv6 - NS */ + msg = (struct nd_msg *)pkt; + msg->icmph.icmp6_type = IPV6_NDISC_NEIGHBOUR_SOLICITATION; + msg->icmph.icmp6_code = 0; + memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16)); + memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32)); + + /* Set the target address and llsaddr option */ + net_copy_ip6(&msg->target, neigh_addr); + ndisc_insert_option(msg->opt, ND_OPT_SOURCE_LL_ADDR, net_ethaddr, + INETHADDRSZ); + + /* checksum */ + pcsum = csum_partial((__u8 *)msg, len, 0); + csum = csum_ipv6_magic(&net_link_local_ip6, &dst_adr, + len, PROT_ICMPV6, pcsum); + msg->icmph.icmp6_cksum = csum; + pkt += len; + + /* send it! */ + net_send_packet(net_tx_packet, (pkt - net_tx_packet)); +} + +/* + * ip6_send_rs() - Send IPv6 Router Solicitation Message. + * + * A router solicitation is sent to discover a router. RS message creation is + * based on RFC 4861 section 4.1. Router Solicitation Message Format. + */ +void ip6_send_rs(void) +{ + unsigned char enetaddr[6]; + struct rs_msg *msg; + __u16 icmp_len; + uchar *pkt; + unsigned short csum; + unsigned int pcsum; + static unsigned int retry_count; + + if (!ip6_is_unspecified_addr(&net_gateway6) && + net_prefix_length != 0) { + net_set_state(NETLOOP_SUCCESS); + return; + } else if (retry_count >= MAX_RTR_SOLICITATIONS) { + net_set_state(NETLOOP_FAIL); + net_set_timeout_handler(0, NULL); + retry_count = 0; + return; + } + + printf("ROUTER SOLICITATION %d\n", retry_count + 1); + + ip6_make_mult_ethdstaddr(enetaddr, &all_routers); + /* + * ICMP length is the size of ICMP header (8) + one option (8) = 16. + * The option is 2 bytes of type and length + 6 bytes for MAC. + */ + icmp_len = sizeof(struct icmp6hdr) + IP6_NDISC_OPT_SPACE(INETHADDRSZ); + + pkt = (uchar *)net_tx_packet; + pkt += net_set_ether(pkt, enetaddr, PROT_IP6); + pkt += ip6_add_hdr(pkt, &net_link_local_ip6, &all_routers, PROT_ICMPV6, + IPV6_NDISC_HOPLIMIT, icmp_len); + + /* ICMPv6 - RS */ + msg = (struct rs_msg *)pkt; + msg->icmph.icmp6_type = IPV6_NDISC_ROUTER_SOLICITATION; + msg->icmph.icmp6_code = 0; + memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16)); + memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32)); + + /* Set the llsaddr option */ + ndisc_insert_option(msg->opt, ND_OPT_SOURCE_LL_ADDR, net_ethaddr, + INETHADDRSZ); + + /* checksum */ + pcsum = csum_partial((__u8 *)msg, icmp_len, 0); + csum = csum_ipv6_magic(&net_link_local_ip6, &all_routers, + icmp_len, PROT_ICMPV6, pcsum); + msg->icmph.icmp6_cksum = csum; + pkt += icmp_len; + + /* Wait up to 1 second if it is the first try to get the RA */ + if (retry_count == 0) + udelay(((unsigned int)rand() % 1000000) * MAX_SOLICITATION_DELAY); + + /* send it! */ + net_send_packet(net_tx_packet, (pkt - net_tx_packet)); + + retry_count++; + net_set_timeout_handler(RTR_SOLICITATION_INTERVAL, ip6_send_rs); +} + +static void +ip6_send_na(uchar *eth_dst_addr, struct in6_addr *neigh_addr, + struct in6_addr *target) +{ + struct nd_msg *msg; + __u16 len; + uchar *pkt; + unsigned short csum; + + debug("sending neighbor advertisement for %pI6c to %pI6c (%pM)\n", + target, neigh_addr, eth_dst_addr); + + len = sizeof(struct icmp6hdr) + IN6ADDRSZ + + IP6_NDISC_OPT_SPACE(INETHADDRSZ); + + pkt = (uchar *)net_tx_packet; + pkt += net_set_ether(pkt, eth_dst_addr, PROT_IP6); + pkt += ip6_add_hdr(pkt, &net_link_local_ip6, neigh_addr, + PROT_ICMPV6, IPV6_NDISC_HOPLIMIT, len); + + /* ICMPv6 - NA */ + msg = (struct nd_msg *)pkt; + msg->icmph.icmp6_type = IPV6_NDISC_NEIGHBOUR_ADVERTISEMENT; + msg->icmph.icmp6_code = 0; + memset(&msg->icmph.icmp6_cksum, 0, sizeof(__be16)); + memset(&msg->icmph.icmp6_unused, 0, sizeof(__be32)); + msg->icmph.icmp6_dataun.u_nd_advt.solicited = 1; + msg->icmph.icmp6_dataun.u_nd_advt.override = 1; + /* Set the target address and lltargetaddr option */ + net_copy_ip6(&msg->target, target); + ndisc_insert_option(msg->opt, ND_OPT_TARGET_LL_ADDR, net_ethaddr, + INETHADDRSZ); + + /* checksum */ + csum = csum_ipv6_magic(&net_link_local_ip6, + neigh_addr, len, PROT_ICMPV6, + csum_partial((__u8 *)msg, len, 0)); + msg->icmph.icmp6_cksum = csum; + pkt += len; + + /* send it! */ + net_send_packet(net_tx_packet, (pkt - net_tx_packet)); +} + +void ndisc_request(void) +{ + if (!ip6_addr_in_subnet(&net_ip6, &net_nd_sol_packet_ip6, + net_prefix_length)) { + if (ip6_is_unspecified_addr(&net_gateway6)) { + puts("## Warning: gatewayip6 is needed but not set\n"); + net_nd_rep_packet_ip6 = net_nd_sol_packet_ip6; + } else { + net_nd_rep_packet_ip6 = net_gateway6; + } + } else { + net_nd_rep_packet_ip6 = net_nd_sol_packet_ip6; + } + + ip6_send_ns(&net_nd_rep_packet_ip6); +} + +int ndisc_timeout_check(void) +{ + ulong t; + + if (ip6_is_unspecified_addr(&net_nd_sol_packet_ip6)) + return 0; + + t = get_timer(0); + + /* check for NDISC timeout */ + if ((t - net_nd_timer_start) > NDISC_TIMEOUT) { + net_nd_try++; + if (net_nd_try >= NDISC_TIMEOUT_COUNT) { + puts("\nNeighbour discovery retry count exceeded; " + "starting again\n"); + net_nd_try = 0; + net_set_state(NETLOOP_FAIL); + } else { + net_nd_timer_start = t; + ndisc_request(); + } + } + return 1; +} + +/* + * ndisc_init() - Make initial steps for ND state machine. + * Usually move variables into initial state. + */ +void ndisc_init(void) +{ + net_nd_packet_mac = NULL; + net_nd_tx_packet = NULL; + net_nd_sol_packet_ip6 = net_null_addr_ip6; + net_nd_rep_packet_ip6 = net_null_addr_ip6; + net_nd_tx_packet_size = 0; + net_nd_tx_packet = &net_nd_packet_buf[0] + (PKTALIGN - 1); + net_nd_tx_packet -= (ulong)net_nd_tx_packet % PKTALIGN; +} + +/* + * validate_ra() - Validate the router advertisement message. + * + * @ip6: Pointer to the router advertisement packet + * + * Check if the router advertisement message is valid. Conditions are + * according to RFC 4861 section 6.1.2. Validation of Router Advertisement + * Messages. + * + * Return: true if the message is valid and false if it is invalid. + */ +bool validate_ra(struct ip6_hdr *ip6) +{ + struct icmp6hdr *icmp = (struct icmp6hdr *)(ip6 + 1); + + /* ICMP length (derived from the IP length) should be 16 or more octets. */ + if (ip6->payload_len < 16) + return false; + + /* Source IP Address should be a valid link-local address. */ + if ((ntohs(ip6->saddr.s6_addr16[0]) & IPV6_LINK_LOCAL_MASK) != + IPV6_LINK_LOCAL_PREFIX) + return false; + + /* + * The IP Hop Limit field should have a value of 255, i.e., the packet + * could not possibly have been forwarded by a router. + */ + if (ip6->hop_limit != 255) + return false; + + /* ICMP checksum has already been checked in net_ip6_handler. */ + + if (icmp->icmp6_code != 0) + return false; + + return true; +} + +/* + * process_ra() - Process the router advertisement packet. + * + * @ip6: Pointer to the router advertisement packet + * @len: Length of the router advertisement packet + * + * Process the received router advertisement message. + * Although RFC 4861 requires retaining at least two router addresses, we only + * keep one because of the U-Boot limitations and its goal of lightweight code. + * + * Return: 0 - RA is a default router and contains valid prefix information. + * Non-zero - RA options are invalid or do not indicate it is a default router + * or do not contain valid prefix information. + */ +int process_ra(struct ip6_hdr *ip6, int len) +{ + /* Pointer to the ICMP section of the packet */ + struct icmp6hdr *icmp = (struct icmp6hdr *)(ip6 + 1); + struct ra_msg *msg = (struct ra_msg *)icmp; + int remaining_option_len = len - IP6_HDR_SIZE - sizeof(struct ra_msg); + unsigned short int option_len; /* Length of each option */ + /* Pointer to the ICMPv6 message options */ + unsigned char *option = NULL; + /* 8-bit identifier of the type of ICMPv6 option */ + unsigned char type = 0; + struct icmp6_ra_prefix_info *prefix = NULL; + + if (len > ETH_MAX_MTU) + return -EMSGSIZE; + /* Ignore the packet if router lifetime is 0. */ + if (!icmp->icmp6_rt_lifetime) + return -EOPNOTSUPP; + + /* Processing the options */ + option = msg->opt; + while (remaining_option_len > 0) { + /* The 2nd byte of the option is its length. */ + option_len = option[1]; + /* All included options should have a positive length. */ + if (option_len == 0) + return -EINVAL; + + type = option[0]; + /* All option types except Prefix Information are ignored. */ + switch (type) { + case ND_OPT_SOURCE_LL_ADDR: + case ND_OPT_TARGET_LL_ADDR: + case ND_OPT_REDIRECT_HDR: + case ND_OPT_MTU: + break; + case ND_OPT_PREFIX_INFO: + prefix = (struct icmp6_ra_prefix_info *)option; + /* The link-local prefix 0xfe80::/10 is ignored. */ + if ((ntohs(prefix->prefix.s6_addr16[0]) & + IPV6_LINK_LOCAL_MASK) == IPV6_LINK_LOCAL_PREFIX) + break; + if (prefix->on_link && ntohl(prefix->valid_lifetime)) { + net_prefix_length = prefix->prefix_len; + net_gateway6 = ip6->saddr; + return 0; + } + break; + default: + debug("Unknown IPv6 Neighbor Discovery Option 0x%x\n", + type); + } + + option_len <<= 3; /* Option length is a multiple of 8. */ + remaining_option_len -= option_len; + option += option_len; + } + + return -EADDRNOTAVAIL; +} + +int ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len) +{ + struct icmp6hdr *icmp = + (struct icmp6hdr *)(((uchar *)ip6) + IP6_HDR_SIZE); + struct nd_msg *ndisc = (struct nd_msg *)icmp; + uchar neigh_eth_addr[6]; + int err = 0; // The error code returned calling functions. + + switch (icmp->icmp6_type) { + case IPV6_NDISC_NEIGHBOUR_SOLICITATION: + debug("received neighbor solicitation for %pI6c from %pI6c\n", + &ndisc->target, &ip6->saddr); + if (ip6_is_our_addr(&ndisc->target) && + ndisc_has_option(ip6, ND_OPT_SOURCE_LL_ADDR)) { + ndisc_extract_enetaddr(ndisc, neigh_eth_addr); + ip6_send_na(neigh_eth_addr, &ip6->saddr, + &ndisc->target); + } + break; + + case IPV6_NDISC_NEIGHBOUR_ADVERTISEMENT: + /* are we waiting for a reply ? */ + if (ip6_is_unspecified_addr(&net_nd_sol_packet_ip6)) + break; + + if ((memcmp(&ndisc->target, &net_nd_rep_packet_ip6, + sizeof(struct in6_addr)) == 0) && + ndisc_has_option(ip6, ND_OPT_TARGET_LL_ADDR)) { + ndisc_extract_enetaddr(ndisc, neigh_eth_addr); + + /* save address for later use */ + if (!net_nd_packet_mac) + net_nd_packet_mac = neigh_eth_addr; + + /* modify header, and transmit it */ + memcpy(((struct ethernet_hdr *)net_nd_tx_packet)->et_dest, + neigh_eth_addr, 6); + + net_send_packet(net_nd_tx_packet, + net_nd_tx_packet_size); + + /* no ND request pending now */ + net_nd_sol_packet_ip6 = net_null_addr_ip6; + net_nd_tx_packet_size = 0; + net_nd_packet_mac = NULL; + } + break; + case IPV6_NDISC_ROUTER_SOLICITATION: + break; + case IPV6_NDISC_ROUTER_ADVERTISEMENT: + debug("Received router advertisement for %pI6c from %pI6c\n", + &ip6->daddr, &ip6->saddr); + /* + * If gateway and prefix are set, the RA packet is ignored. The + * reason is that the U-Boot code is supposed to be as compact + * as possible and does not need to take care of multiple + * routers. In addition to that, U-Boot does not want to handle + * scenarios like a router setting its lifetime to zero to + * indicate it is not routing anymore. U-Boot program has a + * short life when the system boots up and does not need such + * sophistication. + */ + if (!ip6_is_unspecified_addr(&net_gateway6) && + net_prefix_length != 0) { + break; + } + if (!validate_ra(ip6)) { + debug("Invalid router advertisement message.\n"); + break; + } + err = process_ra(ip6, len); + if (err) + debug("Ignored router advertisement. Error: %d\n", err); + else + printf("Set gatewayip6: %pI6c, prefix_length: %d\n", + &net_gateway6, net_prefix_length); + break; + default: + debug("Unexpected ICMPv6 type 0x%x\n", icmp->icmp6_type); + return -1; + } + + return 0; +} |