src/libsystemd-network/dhcp-network.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright (C) 2013 Intel Corporation. All rights reserved.
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <net/ethernet.h>
  22 #include <net/if_arp.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <sys/socket.h>
  26 #include <linux/filter.h>
  27 #include <linux/if_infiniband.h>
  28 #include <linux/if_packet.h>
  29
  30 #include "dhcp-internal.h"
  31 #include "fd-util.h"
  32 #include "socket-util.h"
  33
  34 static int _bind_raw_socket(int ifindex, union sockaddr_union *link,
  35                             uint32_t xid, const uint8_t *mac_addr,
  36                             size_t mac_addr_len,
  37                             const uint8_t *bcast_addr,
  38                             const struct ether_addr *eth_mac,
  39                             uint16_t arp_type, uint8_t dhcp_hlen) {
  40         struct sock_filter filter[] = {
  41                 BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0),                                 /* A <- packet length */
  42                 BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(DHCPPacket), 1, 0),         /* packet >= DHCPPacket ? */
  43                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  44                 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
  45                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0),                /* IP protocol == UDP ? */
  46                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  47                 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags */
  48                 BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x20),                             /* A <- A & 0x20 (More Fragments bit) */
  49                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                          /* A == 0 ? */
  50                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  51                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */
  52                 BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff),                           /* A <- A & 0x1fff (Fragment offset) */
  53                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                          /* A == 0 ? */
  54                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  55                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)),    /* A <- UDP destination port */
  56                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_PORT_CLIENT, 1, 0),           /* UDP destination port == DHCP client port ? */
  57                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  58                 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.op)),     /* A <- DHCP op */
  59                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTREPLY, 1, 0),                  /* op == BOOTREPLY ? */
  60                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  61                 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.htype)),  /* A <- DHCP header type */
  62                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, arp_type, 1, 0),                   /* header type == arp_type ? */
  63                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  64                 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.hlen)),   /* A <- MAC address length */
  65                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, dhcp_hlen, 1, 0),                  /* address length == dhcp_hlen ? */
  66                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  67                 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.xid)),    /* A <- client identifier */
  68                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, xid, 1, 0),                        /* client identifier == xid ? */
  69                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  70                 BPF_STMT(BPF_LD + BPF_IMM, htobe32(*((unsigned int *) eth_mac))),                     /* A <- 4 bytes of client's MAC */
  71                 BPF_STMT(BPF_MISC + BPF_TAX, 0),                                                       /* X <- A */
  72                 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr)),                 /* A <- 4 bytes of MAC from dhcp.chaddr */
  73                 BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                                /* A xor X */
  74                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                                          /* A == 0 ? */
  75                 BPF_STMT(BPF_RET + BPF_K, 0),                                                          /* ignore */
  76                 BPF_STMT(BPF_LD + BPF_IMM, htobe16(*((unsigned short *) (((char *) eth_mac) + 4)))),   /* A <- remainder of client's MAC */
  77                 BPF_STMT(BPF_MISC + BPF_TAX, 0),                                                       /* X <- A */
  78                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr) + 4),             /* A <- remainder of MAC from dhcp.chaddr */
  79                 BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0),                                                /* A xor X */
  80                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0),                                          /* A == 0 ? */
  81                 BPF_STMT(BPF_RET + BPF_K, 0),                                                          /* ignore */
  82                 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.magic)),  /* A <- DHCP magic cookie */
  83                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_MAGIC_COOKIE, 1, 0),          /* cookie == DHCP magic cookie ? */
  84                 BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  85                 BPF_STMT(BPF_RET + BPF_K, 65535),                                      /* return all */
  86         };
  87         struct sock_fprog fprog = {
  88                 .len = ELEMENTSOF(filter),
  89                 .filter = filter
  90         };
  91         _cleanup_close_ int s = -1;
  92         int r, on = 1;
  93
  94         assert(ifindex > 0);
  95         assert(link);
  96
  97         s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
  98         if (s < 0)
  99                 return -errno;
 100
 101         r = setsockopt(s, SOL_PACKET, PACKET_AUXDATA, &on, sizeof(on));
 102         if (r < 0)
 103                 return -errno;
 104
 105         r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
 106         if (r < 0)
 107                 return -errno;
 108
 109         link->ll.sll_family = AF_PACKET;
 110         link->ll.sll_protocol = htobe16(ETH_P_IP);
 111         link->ll.sll_ifindex = ifindex;
 112         link->ll.sll_hatype = htobe16(arp_type);
 113         link->ll.sll_halen = mac_addr_len;
 114         memcpy(link->ll.sll_addr, bcast_addr, mac_addr_len);
 115
 116         r = bind(s, &link->sa, sizeof(link->ll));
 117         if (r < 0)
 118                 return -errno;
 119
 120         r = s;
 121         s = -1;
 122
 123         return r;
 124 }
 125
 126 int dhcp_network_bind_raw_socket(int ifindex, union sockaddr_union *link,
 127                                  uint32_t xid, const uint8_t *mac_addr,
 128                                  size_t mac_addr_len, uint16_t arp_type) {
 129         static const uint8_t eth_bcast[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
 130         /* Default broadcast address for IPoIB */
 131         static const uint8_t ib_bcast[] = {
 132                 0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b,
 133                 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 134                 0xff, 0xff, 0xff, 0xff
 135           };
 136         struct ether_addr eth_mac = { { 0, 0, 0, 0, 0, 0 } };
 137         const uint8_t *bcast_addr = NULL;
 138         uint8_t dhcp_hlen = 0;
 139
 140         assert_return(mac_addr_len > 0, -EINVAL);
 141
 142         if (arp_type == ARPHRD_ETHER) {
 143                 assert_return(mac_addr_len == ETH_ALEN, -EINVAL);
 144                 memcpy(&eth_mac, mac_addr, ETH_ALEN);
 145                 bcast_addr = eth_bcast;
 146                 dhcp_hlen = ETH_ALEN;
 147         } else if (arp_type == ARPHRD_INFINIBAND) {
 148                 assert_return(mac_addr_len == INFINIBAND_ALEN, -EINVAL);
 149                 bcast_addr = ib_bcast;
 150         } else
 151                 return -EINVAL;
 152
 153         return _bind_raw_socket(ifindex, link, xid, mac_addr, mac_addr_len,
 154                                 bcast_addr, &eth_mac, arp_type, dhcp_hlen);
 155 }
 156
 157 int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
 158         union sockaddr_union src = {
 159                 .in.sin_family = AF_INET,
 160                 .in.sin_port = htobe16(port),
 161                 .in.sin_addr.s_addr = address,
 162         };
 163         _cleanup_close_ int s = -1;
 164         int r, on = 1, tos = IPTOS_CLASS_CS6;
 165
 166         s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
 167         if (s < 0)
 168                 return -errno;
 169
 170         r = setsockopt(s, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
 171         if (r < 0)
 172                 return -errno;
 173
 174         r = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
 175         if (r < 0)
 176                 return -errno;
 177
 178         if (address == INADDR_ANY) {
 179                 r = setsockopt(s, IPPROTO_IP, IP_PKTINFO, &on, sizeof(on));
 180                 if (r < 0)
 181                         return -errno;
 182
 183                 r = setsockopt(s, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on));
 184                 if (r < 0)
 185                         return -errno;
 186         } else {
 187                 r = setsockopt(s, IPPROTO_IP, IP_FREEBIND, &on, sizeof(on));
 188                 if (r < 0)
 189                         return -errno;
 190         }
 191
 192         r = bind(s, &src.sa, sizeof(src.in));
 193         if (r < 0)
 194                 return -errno;
 195
 196         r = s;
 197         s = -1;
 198
 199         return r;
 200 }
 201
 202 int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
 203                                  const void *packet, size_t len) {
 204         int r;
 205
 206         assert(link);
 207         assert(packet);
 208         assert(len);
 209
 210         r = sendto(s, packet, len, 0, &link->sa, sizeof(link->ll));
 211         if (r < 0)
 212                 return -errno;
 213
 214         return 0;
 215 }
 216
 217 int dhcp_network_send_udp_socket(int s, be32_t address, uint16_t port,
 218                                  const void *packet, size_t len) {
 219         union sockaddr_union dest = {
 220                 .in.sin_family = AF_INET,
 221                 .in.sin_port = htobe16(port),
 222                 .in.sin_addr.s_addr = address,
 223         };
 224         int r;
 225
 226         assert(s >= 0);
 227         assert(packet);
 228         assert(len);
 229
 230         r = sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in));
 231         if (r < 0)
 232                 return -errno;
 233
 234         return 0;
 235 }