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