[PATCH 04/17] net: ipv6: Add Neighbor Discovery Protocol (NDP)
Ramon Fried
rfried.dev at gmail.com
Mon Sep 12 08:57:23 CEST 2022
On Tue, Sep 6, 2022 at 6:10 PM Viacheslav Mitrofanov
<v.v.mitrofanov at yadro.com> wrote:
>
> Implement basic of NDP. It doesn't include such things as Router
> Solicitation, Router Advertisement and Redirect. It just has Neighbor
> Solicitation and Neighbor Advertisement. Only these two features are used
> in u-boot IPv6. Implementation of some NDP functions uses API that was
> exposed in "net: ipv6: Add IPv6 basic primitives".
>
> Also this patch inlcudes update in Makefile to build NDP.
>
> Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov at yadro.com>
> ---
> include/ndisc.h | 102 +++++++++++++++++
> net/Makefile | 1 +
> net/ndisc.c | 289 ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 392 insertions(+)
> create mode 100644 include/ndisc.h
> create mode 100644 net/ndisc.c
>
> diff --git a/include/ndisc.h b/include/ndisc.h
> new file mode 100644
> index 0000000000..26e6fcc85d
> --- /dev/null
> +++ b/include/ndisc.h
> @@ -0,0 +1,102 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (C) 2013 Allied Telesis Labs NZ
> + * Chris Packham, <judge.packham at gmail.com>
> + *
> + * Copyright (C) 2022 YADRO
> + * Viacheslav Mitrofanov <v.v.mitrofanov at yadro.com>
> + */
> +
> +#ifndef __NDISC_H__
> +#define __NDISC_H__
> +
> +#include <ndisc.h>
> +
> +/* struct nd_msg - ICMPv6 Neighbour Discovery message format */
> +struct nd_msg {
> + struct icmp6hdr icmph;
> + struct in6_addr target;
> + __u8 opt[0];
> +};
> +
> +/* struct echo_msg - ICMPv6 echo request/reply message format */
> +struct echo_msg {
> + struct icmp6hdr icmph;
> + __u16 id;
> + __u16 sequence;
> +};
> +
> +/* Neigbour Discovery option types */
> +enum {
> + __ND_OPT_PREFIX_INFO_END = 0,
> + ND_OPT_SOURCE_LL_ADDR = 1,
> + ND_OPT_TARGET_LL_ADDR = 2,
> + ND_OPT_PREFIX_INFO = 3,
> + ND_OPT_REDIRECT_HDR = 4,
> + ND_OPT_MTU = 5,
> + __ND_OPT_MAX
> +};
> +
> +/* IPv6 destination address of packet waiting for ND */
> +extern struct in6_addr net_nd_sol_packet_ip6;
> +/* MAC destination address of packet waiting for ND */
> +extern uchar *net_nd_packet_mac;
> +/* pointer to packet waiting to be transmitted after ND is resolved */
> +extern uchar *net_nd_tx_packet;
> +/* size of packet waiting to be transmitted */
> +extern int net_nd_tx_packet_size;
> +/* the timer for ND resolution */
> +extern ulong net_nd_timer_start;
> +/* the number of requests we have sent so far */
> +extern int net_nd_try;
> +
> +#ifdef CONFIG_IPV6
> +/**
> + * Make initial steps for ND state machine. Usually move variables into
> + * initial state.
> + */
> +void ndisc_init(void);
> +
> +/**
> + * Handle ND packet
> + *
> + * @param et pointer to incoming packet
> + * @param ip6 pointer to IPv6 header
> + * @param len incoming packet length
> + * @return 0 if handle successfully, -1 if unsupported/unknown ND packet type
> + */
> +int ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len);
> +
> +/**
> + * Send ND request
> + */
> +void ndisc_request(void);
> +
> +/**
> + * Check ND response timeout
> + *
> + * @return 0 if no timeout, -1 otherwise
> + */
> +int ndisc_timeout_check(void);
> +#else
> +static inline void ndisc_init(void)
> +{
> +}
> +
> +static inline int
> +ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len)
> +{
> + return -1;
> +}
> +
> +static inline void ndisc_request(void)
> +{
> +}
> +
> +static inline int ndisc_timeout_check(void)
> +{
> + return 0;
> +}
> +#endif
> +
> +#endif /* __NDISC_H__ */
> diff --git a/net/Makefile b/net/Makefile
> index 4ea2a14f27..766dd04135 100644
> --- a/net/Makefile
> +++ b/net/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_DM_MDIO) += mdio-uclass.o
> obj-$(CONFIG_DM_MDIO_MUX) += mdio-mux-uclass.o
> obj-$(CONFIG_NET) += eth_common.o
> obj-$(CONFIG_CMD_LINK_LOCAL) += link_local.o
> +obj-$(CONFIG_IPV6) += ndisc.o
> obj-$(CONFIG_NET) += net.o
> obj-$(CONFIG_IPV6) += net6.o
> obj-$(CONFIG_CMD_NFS) += nfs.o
> diff --git a/net/ndisc.c b/net/ndisc.c
> new file mode 100644
> index 0000000000..8d05c7404b
> --- /dev/null
> +++ b/net/ndisc.c
> @@ -0,0 +1,289 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2013 Allied Telesis Labs NZ
> + * Chris Packham, <judge.packham at gmail.com>
> + *
> + * Copyright (C) 2022 YADRO
> + * Viacheslav Mitrofanov <v.v.mitrofanov at yadro.com>
> + */
> +
> +/* Neighbour Discovery for IPv6 */
> +
> +#include <common.h>
> +#include <net.h>
> +#include <net6.h>
> +#include <ndisc.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;
> +
> +#define IP6_NDISC_OPT_SPACE(len) (((len) + 2 + 7) & ~7)
> +
> +/**
> + * Insert an option into a neighbor discovery packet.
> + *
> + * @param ndisc pointer to ND packet
> + * @param type option type to insert
> + * @param data option data to insert
> + * @param len data length
> + * @return the number of bytes inserted (which may be >= len)
> + */
> +static int
> +ndisc_insert_option(struct nd_msg *ndisc, int type, u8 *data, int len)
> +{
> + int space = IP6_NDISC_OPT_SPACE(len);
> +
> + ndisc->opt[0] = type;
> + ndisc->opt[1] = space >> 3;
> + memcpy(&ndisc->opt[2], data, len);
> + len += 2;
> +
> + /* fill the remainder with 0 */
> + if (space - len > 0)
> + memset(&ndisc->opt[len], '\0', space - len);
> +
> + return space;
> +}
> +
> +/**
> + * Extract the Ethernet address from a neighbor discovery 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.
> + *
> + * @param ndisc pointer to ND packet
> + * @param enetaddr extracted MAC addr
> + */
> +static void ndisc_extract_enetaddr(struct nd_msg *ndisc, uchar enetaddr[6])
> +{
> + memcpy(enetaddr, &ndisc->opt[2], 6);
> +}
> +
> +/**
> + * Check if the neighbor discovery packet has the specified option set
> + *
> + * @param ip6 pointer to IPv6 header
> + * @param 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, 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));
> +}
> +
> +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, 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;
> +}
> +
> +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;
> +}
> +
> +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];
> +
> + 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)
> + memcpy(net_nd_packet_mac, neigh_eth_addr, 7);
> +
> + /* 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;
> + default:
> + debug("Unexpected ICMPv6 type 0x%x\n", icmp->icmp6_type);
> + return -1;
> + }
> +
> + return 0;
> +}
> --
> 2.25.1
>
Reviewed-by: Ramon Fried <rfried.dev at gmail.com>
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