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 "in-addr-util.h"
  21 #include "io-util.h"
  22 #include "socket-util.h"
  23
  24 #define IN6ADDR_ALL_ROUTERS_MULTICAST_INIT \
  25         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  26               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } } }
  27
  28 #define IN6ADDR_ALL_NODES_MULTICAST_INIT \
  29         { { { 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  30               0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01 } } }
  31
  32 static int icmp6_bind_router_message(const struct icmp6_filter *filter,
  33                                      const struct ipv6_mreq *mreq) {
  34         int ifindex = mreq->ipv6mr_interface;
  35         _cleanup_close_ int s = -1;
  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, ifindex);
  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         r = socket_bind_to_ifindex(s, ifindex);
  79         if (r < 0)
  80                 return r;
  81
  82         return TAKE_FD(s);
  83 }
  84
  85 int icmp6_bind_router_solicitation(int index) {
  86         struct icmp6_filter filter = {};
  87         struct ipv6_mreq mreq = {
  88                 .ipv6mr_multiaddr = IN6ADDR_ALL_NODES_MULTICAST_INIT,
  89                 .ipv6mr_interface = index,
  90         };
  91
  92         ICMP6_FILTER_SETBLOCKALL(&filter);
  93         ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
  94
  95         return icmp6_bind_router_message(&filter, &mreq);
  96 }
  97
  98 int icmp6_bind_router_advertisement(int index) {
  99         struct icmp6_filter filter = {};
 100         struct ipv6_mreq mreq = {
 101                 .ipv6mr_multiaddr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
 102                 .ipv6mr_interface = index,
 103         };
 104
 105         ICMP6_FILTER_SETBLOCKALL(&filter);
 106         ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
 107
 108         return icmp6_bind_router_message(&filter, &mreq);
 109 }
 110
 111 int icmp6_send_router_solicitation(int s, const struct ether_addr *ether_addr) {
 112         struct sockaddr_in6 dst = {
 113                 .sin6_family = AF_INET6,
 114                 .sin6_addr = IN6ADDR_ALL_ROUTERS_MULTICAST_INIT,
 115         };
 116         struct {
 117                 struct nd_router_solicit rs;
 118                 struct nd_opt_hdr rs_opt;
 119                 struct ether_addr rs_opt_mac;
 120         } _packed_ rs = {
 121                 .rs.nd_rs_type = ND_ROUTER_SOLICIT,
 122                 .rs_opt.nd_opt_type = ND_OPT_SOURCE_LINKADDR,
 123                 .rs_opt.nd_opt_len = 1,
 124         };
 125         struct iovec iov = {
 126                 .iov_base = &rs,
 127                 .iov_len = sizeof(rs),
 128         };
 129         struct msghdr msg = {
 130                 .msg_name = &dst,
 131                 .msg_namelen = sizeof(dst),
 132                 .msg_iov = &iov,
 133                 .msg_iovlen = 1,
 134         };
 135         int r;
 136
 137         assert(s >= 0);
 138         assert(ether_addr);
 139
 140         rs.rs_opt_mac = *ether_addr;
 141
 142         r = sendmsg(s, &msg, 0);
 143         if (r < 0)
 144                 return -errno;
 145
 146         return 0;
 147 }
 148
 149 int icmp6_receive(int fd, void *buffer, size_t size, struct in6_addr *dst,
 150                   triple_timestamp *timestamp) {
 151         union {
 152                 struct cmsghdr cmsghdr;
 153                 uint8_t buf[CMSG_SPACE(sizeof(int)) + /* ttl */
 154                             CMSG_SPACE(sizeof(struct timeval))];
 155         } control = {};
 156         struct iovec iov = {};
 157         union sockaddr_union sa = {};
 158         struct msghdr msg = {
 159                 .msg_name = &sa.sa,
 160                 .msg_namelen = sizeof(sa),
 161                 .msg_iov = &iov,
 162                 .msg_iovlen = 1,
 163                 .msg_control = &control,
 164                 .msg_controllen = sizeof(control),
 165         };
 166         struct cmsghdr *cmsg;
 167         ssize_t len;
 168
 169         iov = IOVEC_MAKE(buffer, size);
 170
 171         len = recvmsg(fd, &msg, MSG_DONTWAIT);
 172         if (len < 0)
 173                 return -errno;
 174
 175         if ((size_t) len != size)
 176                 return -EINVAL;
 177
 178         if (msg.msg_namelen == sizeof(struct sockaddr_in6) &&
 179             sa.in6.sin6_family == AF_INET6)  {
 180
 181                 *dst = sa.in6.sin6_addr;
 182                 if (in_addr_is_link_local(AF_INET6, (union in_addr_union*) dst) <= 0)
 183                         return -EADDRNOTAVAIL;
 184
 185         } else if (msg.msg_namelen > 0)
 186                 return -EPFNOSUPPORT;
 187
 188         /* namelen == 0 only happens when running the test-suite over a socketpair */
 189
 190         assert(!(msg.msg_flags & MSG_CTRUNC));
 191         assert(!(msg.msg_flags & MSG_TRUNC));
 192
 193         CMSG_FOREACH(cmsg, &msg) {
 194                 if (cmsg->cmsg_level == SOL_IPV6 &&
 195                     cmsg->cmsg_type == IPV6_HOPLIMIT &&
 196                     cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
 197                         int hops = *(int*) CMSG_DATA(cmsg);
 198
 199                         if (hops != 255)
 200                                 return -EMULTIHOP;
 201                 }
 202
 203                 if (cmsg->cmsg_level == SOL_SOCKET &&
 204                     cmsg->cmsg_type == SO_TIMESTAMP &&
 205                     cmsg->cmsg_len == CMSG_LEN(sizeof(struct timeval)))
 206                         triple_timestamp_from_realtime(timestamp, timeval_load((struct timeval*) CMSG_DATA(cmsg)));
 207         }
 208
 209         if (!triple_timestamp_is_set(timestamp))
 210                 triple_timestamp_get(timestamp);
 211
 212         return 0;
 213 }