mirrors/passt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
passt/ndp.c
David Gibson 905ecd2b0b treewide: Rename MAC address fields for clarity 
c->mac isn't a great name, because it doesn't say whose mac address it is
and it's not necessarily obvious in all the contexts we use it.  Since this
is specifically the address that we (passt/pasta) use on the tap interface,
rename it to "our_tap_mac".  Rename the "mac_guest" field to "guest_mac"
to be grammatically consistent.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2024-08-21 11:59:54 +02:00

358 lines
7.8 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* ndp.c - NDP support for PASST
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*
*/
#include <stdio.h>
#include <stddef.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/ip.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/if_ether.h>
#include <linux/icmpv6.h>
#include "checksum.h"
#include "util.h"
#include "ip.h"
#include "passt.h"
#include "tap.h"
#include "log.h"
#define RS 133
#define RA 134
#define NS 135
#define NA 136
enum ndp_option_types {
OPT_SRC_L2_ADDR = 1,
OPT_TARGET_L2_ADDR = 2,
OPT_PREFIX_INFO = 3,
OPT_MTU = 5,
OPT_RDNSS_TYPE = 25,
OPT_DNSSL_TYPE = 31,
};
/**
* struct opt_header - Option header
* @type: Option type
* @len: Option length, in units of 8 bytes
*/
struct opt_header {
uint8_t type;
uint8_t len;
} __attribute__((packed));
/**
* struct opt_l2_addr - Link-layer address
* @header: Option header
* @mac: MAC address
*/
struct opt_l2_addr {
struct opt_header header;
unsigned char mac[ETH_ALEN];
} __attribute__((packed));
/**
* struct ndp_na - NDP Neighbor Advertisement (NA) message
* @ih: ICMPv6 header
* @target_addr: Target IPv6 address
* @target_l2_addr: Target link-layer address
*/
struct ndp_na {
struct icmp6hdr ih;
struct in6_addr target_addr;
struct opt_l2_addr target_l2_addr;
} __attribute__((packed));
/**
* struct opt_prefix_info - Prefix Information option
* @header: Option header
* @prefix_len: The number of leading bits in the Prefix that are valid
* @prefix_flags: Flags associated with the prefix
* @valid_lifetime: Valid lifetime (ms)
* @pref_lifetime: Preferred lifetime (ms)
* @reserved: Unused
*/
struct opt_prefix_info {
struct opt_header header;
uint8_t prefix_len;
uint8_t prefix_flags;
uint32_t valid_lifetime;
uint32_t pref_lifetime;
uint32_t reserved;
} __attribute__((packed));
/**
* struct opt_mtu - Maximum transmission unit (MTU) option
* @header: Option header
* @reserved: Unused
* @value: MTU value, network order
*/
struct opt_mtu {
struct opt_header header;
uint16_t reserved;
uint32_t value;
} __attribute__((packed));
/**
* struct rdnss - Recursive DNS Server (RDNSS) option
* @header: Option header
* @reserved: Unused
* @lifetime: Validity time (s)
* @dns: List of DNS server addresses
*/
struct opt_rdnss {
struct opt_header header;
uint16_t reserved;
uint32_t lifetime;
struct in6_addr dns[MAXNS + 1];
} __attribute__((packed));
/**
* struct dnssl - DNS Search List (DNSSL) option
* @header: Option header
* @reserved: Unused
* @lifetime: Validity time (s)
* @domains: List of NULL-seperated search domains
*/
struct opt_dnssl {
struct opt_header header;
uint16_t reserved;
uint32_t lifetime;
unsigned char domains[MAXDNSRCH * NS_MAXDNAME];
} __attribute__((packed));
/**
* struct ndp_ra - NDP Router Advertisement (RA) message
* @ih: ICMPv6 header
* @reachable: Reachability time, after confirmation (ms)
* @retrans: Time between retransmitted NS messages (ms)
* @prefix_info: Prefix Information option
* @prefix: IPv6 prefix
* @mtu: MTU option
* @source_ll: Target link-layer address
* @var: Variable fields
*/
struct ndp_ra {
struct icmp6hdr ih;
uint32_t reachable;
uint32_t retrans;
struct opt_prefix_info prefix_info;
struct in6_addr prefix;
struct opt_l2_addr source_ll;
unsigned char var[sizeof(struct opt_mtu) + sizeof(struct opt_rdnss) +
sizeof(struct opt_dnssl)];
} __attribute__((packed));
/**
* struct ndp_ns - NDP Neighbor Solicitation (NS) message
* @ih: ICMPv6 header
* @target_addr: Target IPv6 address
*/
struct ndp_ns {
struct icmp6hdr ih;
struct in6_addr target_addr;
} __attribute__((packed));
/**
* ndp() - Check for NDP solicitations, reply as needed
* @c: Execution context
* @ih: ICMPv6 header
* @saddr: Source IPv6 address
* @p: Packet pool
*
* Return: 0 if not handled here, 1 if handled, -1 on failure
*/
int ndp(struct ctx *c, const struct icmp6hdr *ih, const struct in6_addr *saddr,
const struct pool *p)
{
struct ndp_na na = {
.ih = {
.icmp6_type = NA,
.icmp6_code = 0,
.icmp6_router = 1,
.icmp6_solicited = 1,
.icmp6_override = 1,
},
.target_l2_addr = {
.header = {
.type = OPT_TARGET_L2_ADDR,
.len = 1,
},
}
};
struct ndp_ra ra = {
.ih = {
.icmp6_type = RA,
.icmp6_code = 0,
.icmp6_hop_limit = 255,
/* RFC 8319 */
.icmp6_rt_lifetime = htons_constant(65535),
.icmp6_addrconf_managed = 1,
},
.prefix_info = {
.header = {
.type = OPT_PREFIX_INFO,
.len = 4,
},
.prefix_len = 64,
.prefix_flags = 0xc0, /* prefix flags: L, A */
.valid_lifetime = ~0U,
.pref_lifetime = ~0U,
},
.source_ll = {
.header = {
.type = OPT_SRC_L2_ADDR,
.len = 1,
},
},
};
const struct in6_addr *rsaddr; /* src addr for reply */
unsigned char *ptr = NULL;
size_t dlen;
if (ih->icmp6_type < RS || ih->icmp6_type > NA)
return 0;
if (c->no_ndp)
return 1;
if (ih->icmp6_type == NS) {
struct ndp_ns *ns = packet_get(p, 0, 0, sizeof(struct ndp_ns),
NULL);
if (!ns)
return -1;
if (IN6_IS_ADDR_UNSPECIFIED(saddr))
return 1;
info("NDP: received NS, sending NA");
memcpy(&na.target_addr, &ns->target_addr,
sizeof(na.target_addr));
memcpy(na.target_l2_addr.mac, c->our_tap_mac, ETH_ALEN);
} else if (ih->icmp6_type == RS) {
size_t dns_s_len = 0;
int i, n;
if (c->no_ra)
return 1;
info("NDP: received RS, sending RA");
memcpy(&ra.prefix, &c->ip6.addr, sizeof(ra.prefix));
ptr = &ra.var[0];
if (c->mtu != -1) {
struct opt_mtu *mtu = (struct opt_mtu *)ptr;
*mtu = (struct opt_mtu) {
.header = {
.type = OPT_MTU,
.len = 1,
},
.value = htonl(c->mtu),
};
ptr += sizeof(struct opt_mtu);
}
if (c->no_dhcp_dns)
goto dns_done;
for (n = 0; !IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns[n]); n++);
if (n) {
struct opt_rdnss *rdnss = (struct opt_rdnss *)ptr;
*rdnss = (struct opt_rdnss) {
.header = {
.type = OPT_RDNSS_TYPE,
.len = 1 + 2 * n,
},
.lifetime = ~0U,
};
for (i = 0; i < n; i++) {
memcpy(&rdnss->dns[i], &c->ip6.dns[i],
sizeof(rdnss->dns[i]));
}
ptr += offsetof(struct opt_rdnss, dns) +
i * sizeof(rdnss->dns[0]);
for (n = 0; *c->dns_search[n].n; n++)
dns_s_len += strlen(c->dns_search[n].n) + 2;
}
if (!c->no_dhcp_dns_search && dns_s_len) {
struct opt_dnssl *dnssl = (struct opt_dnssl *)ptr;
*dnssl = (struct opt_dnssl) {
.header = {
.type = OPT_DNSSL_TYPE,
.len = DIV_ROUND_UP(dns_s_len, 8) + 1,
},
.lifetime = ~0U,
};
ptr = dnssl->domains;
for (i = 0; i < n; i++) {
size_t len;
char *dot;
*(ptr++) = '.';
len = sizeof(dnssl->domains) -
(ptr - dnssl->domains);
strncpy((char *)ptr, c->dns_search[i].n, len);
for (dot = (char *)ptr - 1; *dot; dot++) {
if (*dot == '.')
*dot = strcspn(dot + 1, ".");
}
ptr += strlen(c->dns_search[i].n);
*(ptr++) = 0;
}
memset(ptr, 0, 8 - dns_s_len % 8); /* padding */
ptr += 8 - dns_s_len % 8;
}
dns_done:
memcpy(&ra.source_ll.mac, c->our_tap_mac, ETH_ALEN);
} else {
return 1;
}
if (IN6_IS_ADDR_LINKLOCAL(saddr))
c->ip6.addr_ll_seen = *saddr;
else
c->ip6.addr_seen = *saddr;
if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
rsaddr = &c->ip6.gw;
else
rsaddr = &c->ip6.addr_ll;
if (ih->icmp6_type == NS) {
dlen = sizeof(struct ndp_na);
tap_icmp6_send(c, rsaddr, saddr, &na, dlen);
} else if (ih->icmp6_type == RS) {
dlen = ptr - (unsigned char *)&ra;
tap_icmp6_send(c, rsaddr, saddr, &ra, dlen);
}
return 1;
}
Reference in a new issue View git blame Copy permalink