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Systemd/src/libsystemd-network/icmp6-util.c
Patrik Flykt 88d5a3db55 sd-radv: Receive Router Solicitations 
Receive Router Solicitations and send a unicast Router Advertisment
in response. Refactor ICMPv6 packet handling code so that the common
ICMPv6 validation parts are reused between the existing router
discovery and the new functionality adding reception of Router
Solicitation messages.
2017-05-15 14:49:50 +03:00

239 lines
7.6 KiB
C
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/***
This file is part of systemd.
Copyright (C) 2014 Intel Corporation. All rights reserved.
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <errno.h>
#include <netinet/icmp6.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <net/if.h>
#include <linux/if_packet.h>
#include "fd-util.h"
#include "icmp6-util.h"
#include "socket-util.h"
#include "in-addr-util.h"
#define IN6ADDR_ALL_ROUTERS_MULTICAST_INIT \
{ { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } } }
#define IN6ADDR_ALL_NODES_MULTICAST_INIT \
{ { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } } }
static int icmp6_bind_router_message(const struct icmp6_filter *filter,
const struct ipv6_mreq *mreq) {
int index = mreq->ipv6mr_interface;
_cleanup_close_ int s = -1;
char ifname[IF_NAMESIZE] = "";
static const int zero = 0, one = 1, hops = 255;
int r;
s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK, IPPROTO_ICMPV6);
if (s < 0)
return -errno;
r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, filter, sizeof(*filter));
if (r < 0)
return -errno;
r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, mreq, sizeof(*mreq));
if (r < 0)
return -errno;
/* RFC 3315, section 6.7, bullet point 2 may indicate that an
IPV6_PKTINFO socket option also applies for ICMPv6 multicast.
Empirical experiments indicates otherwise and therefore an
IPV6_MULTICAST_IF socket option is used here instead */
r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index, sizeof(index));
if (r < 0)
return -errno;
r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero, sizeof(zero));
if (r < 0)
return -errno;
r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops));
if (r < 0)
return -errno;
r = setsockopt(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hops, sizeof(hops));
if (r < 0)
return -errno;
r = setsockopt(s, SOL_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
if (r < 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one));
if (r < 0)
return -errno;
if (if_indextoname(index, ifname) == 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
if (r < 0)
return -errno;
r = s;
s = -1;
return r;
}
int icmp6_bind_router_solicitation(int index) {
struct icmp6_filter filter = {};
struct ipv6_mreq mreq = {
.ipv6mr_multiaddr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
.ipv6mr_interface = index,
};
ICMP6_FILTER_SETBLOCKALL(&filter);
ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
return icmp6_bind_router_message(&filter, &mreq);
}
int icmp6_bind_router_advertisement(int index) {
struct icmp6_filter filter = {};
struct ipv6_mreq mreq = {
.ipv6mr_multiaddr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
.ipv6mr_interface = index,
};
ICMP6_FILTER_SETBLOCKALL(&filter);
ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
return icmp6_bind_router_message(&filter, &mreq);
}
int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
struct sockaddr_in6 dst = {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
};
struct {
struct nd_router_solicit rs;
struct nd_opt_hdr rs_opt;
struct ether_addr rs_opt_mac;
} _packed_ rs = {
.rs.nd_rs_type = ND_ROUTER_SOLICIT,
.rs_opt.nd_opt_type = ND_OPT_SOURCE_LINKADDR,
.rs_opt.nd_opt_len = 1,
};
struct iovec iov = {
.iov_base = &rs,
.iov_len = sizeof(rs),
};
struct msghdr msg = {
.msg_name = &dst,
.msg_namelen = sizeof(dst),
.msg_iov = &iov,
.msg_iovlen = 1,
};
int r;
assert(s >= 0);
assert(ether_addr);
rs.rs_opt_mac = *ether_addr;
r = sendmsg(s, &msg, 0);
if (r < 0)
return -errno;
return 0;
}
int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *dst,
triple_timestamp *timestamp) {
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
CMSG_SPACE(sizeof(struct timeval))];
} control = {};
struct iovec iov = {};
union sockaddr_union sa = {};
struct msghdr msg = {
.msg_name = &sa.sa,
.msg_namelen = sizeof(sa),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = &control,
.msg_controllen = sizeof(control),
};
struct cmsghdr *cmsg;
ssize_t len;
iov.iov_base = buffer;
iov.iov_len = size;
len = recvmsg(fd, &msg, MSG_DONTWAIT);
if (len < 0) {
if (errno == EAGAIN || errno == EINTR)
return 0;
return -errno;
}
if ((size_t) len != size)
return -EINVAL;
if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
sa.in6.sin6_family == AF_INET6) {
*dst = sa.in6.sin6_addr;
if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) dst) <= 0)
return -EADDRNOTAVAIL;
} else if (msg.msg_namelen > 0)
return -EPFNOSUPPORT;
/* namelen == 0 only happens when running the test-suite over a socketpair */
assert(!(msg.msg_flags & MSG_CTRUNC));
assert(!(msg.msg_flags & MSG_TRUNC));
CMSG_FOREACH(cmsg, &msg) {
if (cmsg->cmsg_level == SOL_IPV6 &&
cmsg->cmsg_type == IPV6_HOPLIMIT &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
int hops = *(int*) CMSG_DATA(cmsg);
if (hops != 255)
return -EMULTIHOP;
}
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SO_TIMESTAMP &&
cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
triple_timestamp_from_realtime(timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
}
if (!triple_timestamp_is_set(timestamp))
triple_timestamp_get(timestamp);
return 0;
}
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