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net: ipv6: Add support for default gateway discovery.

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In IPv6, the default gateway and prefix length are determined by receiving
a router advertisement as defined in -
https://www.rfc-editor.org/rfc/rfc4861.

Add support for sending router solicitation (RS) and processing router
advertisements (RA).

If the RA has prefix info option and following conditions are met, then
gatewayip6 and net_prefix_length of ip6addr env variables are initialized.
These are later consumed by IPv6 code for non-local destination IP.

- "Router Lifetime" != 0
- Prefix is NOT link-local prefix (0xfe80::/10)
- L flag is 1
- "Valid Lifetime" != 0

Timing Parameters:
- MAX_RTR_SOLICITATION_DELAY (0-1s)
- RTR_SOLICITATION_INTERVAL (4s) (min retransmit delay)
- MAX_RTR_SOLICITATIONS (3 RS transmissions)

The functionality is enabled by CONFIG_IPV6_ROUTER_DISCOVERY and invoked
automatically from net_init_loop().

Signed-off-by: Ehsan Mohandesi <emohandesi@linux.microsoft.com>
Tested-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>Reviewed-by:
Tested-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
Reviewed-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
Tested-by: Sergei Antonov <saproj@gmail.com>
Reviewed-by: Sergei Antonov <saproj@gmail.com>
This commit is contained in:
Ehsan Mohandesi 2023-04-21 17:08:21 -07:00 committed by Tom Rini
parent 09005c2fb2
commit 6de98b60ba
7 changed files with 338 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
cmd/Kconfig
View file

@ -1942,6 +1942,12 @@ config CMD_NCSI
Normally this happens automatically before other network
operations.
config IPV6_ROUTER_DISCOVERY
bool "Do IPv6 router discovery"
depends on IPV6
help
Will automatically perform router solicitation on first IPv6
network operation
endif
config CMD_ETHSW

35
include/ndisc.h
View file

@ -19,6 +19,20 @@ struct nd_msg {
__u8 opt[0];
};
/* struct rs_msg - ICMPv6 Router Solicitation message format */
struct rs_msg {
struct icmp6hdr icmph;
__u8 opt[0];
};
/* struct ra_msg - ICMPv6 Router Advertisement message format */
struct ra_msg {
struct icmp6hdr icmph;
__u32 reachable_time;
__u32 retransmission_timer;
__u8 opt[0];
};
/* struct echo_msg - ICMPv6 echo request/reply message format */
struct echo_msg {
struct icmp6hdr icmph;
@ -57,6 +71,11 @@ extern int net_nd_try;
*/
void ndisc_init(void);
/*
* ip6_send_rs() - Send IPv6 Router Solicitation Message
*/
void ip6_send_rs(void);
/**
* ndisc_receive() - Handle ND packet
*
@ -78,6 +97,8 @@ void ndisc_request(void);
* Return: 0 if no timeout, -1 otherwise
*/
int ndisc_timeout_check(void);
bool validate_ra(struct ip6_hdr *ip6);
int process_ra(struct ip6_hdr *ip6, int len);
#else
static inline void ndisc_init(void)
{
@ -97,6 +118,20 @@ static inline int ndisc_timeout_check(void)
{
return 0;
}
static inline void ip6_send_rs(void)
{
}
static inline bool validate_ra(struct ip6_hdr *ip6)
{
return true;
}
static inline int process_ra(struct ip6_hdr *ip6, int len)
{
return 0;
}
#endif
#endif /* __NDISC_H__ */

2
include/net.h
View file

@ -508,7 +508,7 @@ extern int net_restart_wrap; /* Tried all network devices */
enum proto_t {
BOOTP, RARP, ARP, TFTPGET, DHCP, DHCP6, PING, PING6, DNS, NFS, CDP,
NETCONS, SNTP, TFTPSRV, TFTPPUT, LINKLOCAL, FASTBOOT_UDP, FASTBOOT_TCP,
WOL, UDP, NCSI, WGET
WOL, UDP, NCSI, WGET, RS
};
extern char net_boot_file_name[1024];/* Boot File name */

40
include/net6.h
View file

@ -81,8 +81,17 @@ struct udp_hdr {
0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00 } } }
/*
* All-routers multicast address is the link-local scope address to reach all
* routers.
*/
#define ALL_ROUTERS_MULT_ADDR { { { 0xFF, 0x02, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x02 } } }
#define IPV6_LINK_LOCAL_PREFIX 0xfe80
#define IPV6_LINK_LOCAL_MASK 0xffb0 /* The first 10-bit of address mask. */
/* hop limit for neighbour discovery packets */
#define IPV6_NDISC_HOPLIMIT 255
@ -166,6 +175,37 @@ struct icmp6hdr {
#define icmp6_rt_lifetime icmp6_dataun.u_nd_ra.rt_lifetime
} __packed;
/*
* struct icmp6_ra_prefix_info - Prefix Information option of the ICMPv6 message
* The Prefix Information option provides hosts with on-link prefixes and
* prefixes for Address Autoconfiguration. Refer to RFC 4861 for more info.
*/
struct icmp6_ra_prefix_info {
u8 type; /* Type is 3 for Prefix Information. */
u8 len; /* Len is 4 for Prefix Information. */
/* The number of leading bits in the Prefix that are valid. */
u8 prefix_len;
u8 reserved1:6, /* MUST be ignored by the receiver. */
aac:1, /* autonomous address-configuration flag */
/* Indicates that this prefix can be used for on-link determination. */
on_link:1;
/*
* The length of time in seconds that the prefix is valid for the
* purpose of on-link determination.
*/
__be32 valid_lifetime;
/* The length of time addresses remain preferred. */
__be32 preferred_lifetime;
__be32 reserved2; /* MUST be ignored by the receiver. */
/*
* Prefix is an IP address or a prefix of an IP address. The Prefix
* Length field contains the number of valid leading bits in the prefix.
* The bits in the prefix after the prefix length are reserved and MUST
* be initialized to zero by the sender and ignored by the receiver.
*/
struct in6_addr prefix;
};
extern struct in6_addr const net_null_addr_ip6; /* NULL IPv6 address */
extern struct in6_addr net_gateway6; /* Our gateways IPv6 address */
extern struct in6_addr net_ip6; /* Our IPv6 addr (0 = unknown) */

243
net/ndisc.c
View file

@ -13,6 +13,8 @@
#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;
@ -29,31 +31,37 @@ int net_nd_tx_packet_size;
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
*
* @ndisc: pointer to ND 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(struct nd_msg *ndisc, int type, u8 *data, int len)
static int ndisc_insert_option(__u8 *opt, 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);
opt[0] = type;
opt[1] = space >> 3;
memcpy(&opt[2], data, len);
len += 2;
/* fill the remainder with 0 */
if (space - len > 0)
memset(&ndisc->opt[len], '\0', space - len);
memset(&opt[len], '\0', space - len);
return space;
}
@ -123,7 +131,7 @@ static void ip6_send_ns(struct in6_addr *neigh_addr)
/* 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,
ndisc_insert_option(msg->opt, ND_OPT_SOURCE_LL_ADDR, net_ethaddr,
INETHADDRSZ);
/* checksum */
@ -137,6 +145,76 @@ static void ip6_send_ns(struct in6_addr *neigh_addr)
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)
@ -167,7 +245,7 @@ ip6_send_na(uchar *eth_dst_addr, struct in6_addr *neigh_addr,
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,
ndisc_insert_option(msg->opt, ND_OPT_TARGET_LL_ADDR, net_ethaddr,
INETHADDRSZ);
/* checksum */
@ -223,6 +301,10 @@ int ndisc_timeout_check(void)
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;
@ -234,12 +316,125 @@ void ndisc_init(void)
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;
/* 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:
@ -280,6 +475,36 @@ int ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len)
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;

23
net/net.c
View file

@ -24,7 +24,7 @@
* - name of bootfile
* Next step: ARP
*
* LINK_LOCAL:
* LINKLOCAL:
*
* Prerequisites: - own ethernet address
* We want: - own IP address
@ -124,6 +124,7 @@
#include "wol.h"
#endif
#include "dhcpv6.h"
#include "net_rand.h"
/** BOOTP EXTENTIONS **/
@ -350,6 +351,8 @@ void net_auto_load(void)
static int net_init_loop(void)
{
static bool first_call = true;
if (eth_get_dev()) {
memcpy(net_ethaddr, eth_get_ethaddr(), 6);
@ -369,6 +372,12 @@ static int net_init_loop(void)
*/
return -ENONET;
if (IS_ENABLED(CONFIG_IPV6_ROUTER_DISCOVERY))
if (first_call && use_ip6) {
first_call = false;
srand_mac(); /* This is for rand used in ip6_send_rs. */
net_loop(RS);
}
return 0;
}
@ -587,6 +596,10 @@ restart:
ncsi_probe_packages();
break;
#endif
case RS:
if (IS_ENABLED(CONFIG_IPV6_ROUTER_DISCOVERY))
ip6_send_rs();
break;
default:
break;
}
@ -684,7 +697,13 @@ restart:
x = time_handler;
time_handler = (thand_f *)0;
(*x)();
}
} else if (IS_ENABLED(CONFIG_IPV6_ROUTER_DISCOVERY))
if (time_handler && protocol == RS)
if (!ip6_is_unspecified_addr(&net_gateway6) &&
net_prefix_length != 0) {
net_set_state(NETLOOP_SUCCESS);
net_set_timeout_handler(0, NULL);
}
if (net_state == NETLOOP_FAIL)
ret = net_start_again();

1
net/net6.c
View file

@ -413,6 +413,7 @@ int net_ip6_handler(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len)
break;
case IPV6_NDISC_NEIGHBOUR_SOLICITATION:
case IPV6_NDISC_NEIGHBOUR_ADVERTISEMENT:
case IPV6_NDISC_ROUTER_ADVERTISEMENT:
ndisc_receive(et, ip6, len);
break;
default: