src/libsystemd-network/icmp6-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright © 2014 Intel Corporation. All rights reserved.
   4 ***/
   5
   6 #include <errno.h>
   7 #include <netinet/icmp6.h>
   8 #include <netinet/in.h>
   9 #include <netinet/ip6.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include <sys/socket.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15 #include <net/if.h>
  16 #include <linux/if_packet.h>
  17
  18 #include "fd-util.h"
  19 #include "icmp6-util.h"
  20 #include "socket-util.h"
  21 #include "in-addr-util.h"
  22
  23 #define IN6ADDR_ALL_ROUTERS_MULTICAST_INIT \
  24         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  25               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } } }
  26
  27 #define IN6ADDR_ALL_NODES_MULTICAST_INIT \
  28         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  29               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } } }
  30
  31 static int icmp6_bind_router_message(const struct icmp6_filter *filter,
  32                                      const struct ipv6_mreq *mreq) {
  33         int index = mreq->ipv6mr_interface;
  34         _cleanup_close_ int s = -1;
  35         char ifname[IF_NAMESIZE] = "";
  36         int r;
  37
  38         s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK, IPPROTO_ICMPV6);
  39         if (s < 0)
  40                 return -errno;
  41
  42         r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, filter, sizeof(*filter));
  43         if (r < 0)
  44                 return -errno;
  45
  46         r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, mreq, sizeof(*mreq));
  47         if (r < 0)
  48                 return -errno;
  49
  50         /* RFC 3315, section 6.7, bullet point 2 may indicate that an
  51            IPV6_PKTINFO socket option also applies for ICMPv6 multicast.
  52            Empirical experiments indicates otherwise and therefore an
  53            IPV6_MULTICAST_IF socket option is used here instead */
  54         r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, index);
  55         if (r < 0)
  56                 return r;
  57
  58         r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, false);
  59         if (r < 0)
  60                 return r;
  61
  62         r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, 255);
  63         if (r < 0)
  64                 return r;
  65
  66         r = setsockopt_int(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, 255);
  67         if (r < 0)
  68                 return r;
  69
  70         r = setsockopt_int(s, SOL_IPV6, IPV6_RECVHOPLIMIT, true);
  71         if (r < 0)
  72                 return r;
  73
  74         r = setsockopt_int(s, SOL_SOCKET, SO_TIMESTAMP, true);
  75         if (r < 0)
  76                 return r;
  77
  78         if (if_indextoname(index, ifname) == 0)
  79                 return -errno;
  80
  81         r = setsockopt(s, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
  82         if (r < 0)
  83                 return -errno;
  84
  85         return TAKE_FD(s);
  86 }
  87
  88 int icmp6_bind_router_solicitation(int index) {
  89         struct icmp6_filter filter = {};
  90         struct ipv6_mreq mreq = {
  91                 .ipv6mr_multiaddr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
  92                 .ipv6mr_interface = index,
  93         };
  94
  95         ICMP6_FILTER_SETBLOCKALL(&filter);
  96         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
  97
  98         return icmp6_bind_router_message(&filter, &mreq);
  99 }
 100
 101 int icmp6_bind_router_advertisement(int index) {
 102         struct icmp6_filter filter = {};
 103         struct ipv6_mreq mreq = {
 104                 .ipv6mr_multiaddr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
 105                 .ipv6mr_interface = index,
 106         };
 107
 108         ICMP6_FILTER_SETBLOCKALL(&filter);
 109         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
 110
 111         return icmp6_bind_router_message(&filter, &mreq);
 112 }
 113
 114 int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
 115         struct sockaddr_in6 dst = {
 116                 .sin6_family = AF_INET6,
 117                 .sin6_addr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
 118         };
 119         struct {
 120                 struct nd_router_solicit rs;
 121                 struct nd_opt_hdr rs_opt;
 122                 struct ether_addr rs_opt_mac;
 123         } _packed_ rs = {
 124                 .rs.nd_rs_type = ND_ROUTER_SOLICIT,
 125                 .rs_opt.nd_opt_type = ND_OPT_SOURCE_LINKADDR,
 126                 .rs_opt.nd_opt_len = 1,
 127         };
 128         struct iovec iov = {
 129                 .iov_base = &rs,
 130                 .iov_len = sizeof(rs),
 131         };
 132         struct msghdr msg = {
 133                 .msg_name = &dst,
 134                 .msg_namelen = sizeof(dst),
 135                 .msg_iov = &iov,
 136                 .msg_iovlen = 1,
 137         };
 138         int r;
 139
 140         assert(s >= 0);
 141         assert(ether_addr);
 142
 143         rs.rs_opt_mac = *ether_addr;
 144
 145         r = sendmsg(s, &msg, 0);
 146         if (r < 0)
 147                 return -errno;
 148
 149         return 0;
 150 }
 151
 152 int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *dst,
 153                   triple_timestamp *timestamp) {
 154         union {
 155                 struct cmsghdr cmsghdr;
 156                 uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
 157                             CMSG_SPACE(sizeof(struct timeval))];
 158         } control = {};
 159         struct iovec iov = {};
 160         union sockaddr_union sa = {};
 161         struct msghdr msg = {
 162                 .msg_name = &sa.sa,
 163                 .msg_namelen = sizeof(sa),
 164                 .msg_iov = &iov,
 165                 .msg_iovlen = 1,
 166                 .msg_control = &control,
 167                 .msg_controllen = sizeof(control),
 168         };
 169         struct cmsghdr *cmsg;
 170         ssize_t len;
 171
 172         iov.iov_base = buffer;
 173         iov.iov_len = size;
 174
 175         len = recvmsg(fd, &msg, MSG_DONTWAIT);
 176         if (len < 0)
 177                 return -errno;
 178
 179         if ((size_t) len != size)
 180                 return -EINVAL;
 181
 182         if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
 183             sa.in6.sin6_family == AF_INET6)  {
 184
 185                 *dst = sa.in6.sin6_addr;
 186                 if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) dst) <= 0)
 187                         return -EADDRNOTAVAIL;
 188
 189         } else if (msg.msg_namelen > 0)
 190                 return -EPFNOSUPPORT;
 191
 192         /* namelen == 0 only happens when running the test-suite over a socketpair */
 193
 194         assert(!(msg.msg_flags & MSG_CTRUNC));
 195         assert(!(msg.msg_flags & MSG_TRUNC));
 196
 197         CMSG_FOREACH(cmsg, &msg) {
 198                 if (cmsg->cmsg_level == SOL_IPV6 &&
 199                     cmsg->cmsg_type == IPV6_HOPLIMIT &&
 200                     cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
 201                         int hops = *(int*) CMSG_DATA(cmsg);
 202
 203                         if (hops != 255)
 204                                 return -EMULTIHOP;
 205                 }
 206
 207                 if (cmsg->cmsg_level == SOL_SOCKET &&
 208                     cmsg->cmsg_type == SO_TIMESTAMP &&
 209                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
 210                         triple_timestamp_from_realtime(timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
 211         }
 212
 213         if (!triple_timestamp_is_set(timestamp))
 214                 triple_timestamp_get(timestamp);
 215
 216         return 0;
 217 }