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 <sys/types.h>
  22 #include <sys/socket.h>
  23 #include <string.h>
  24 #include <linux/if_packet.h>
  25 #include <net/ethernet.h>
  26 #include <net/if_arp.h>
  27 #include <stdio.h>
  28 #include <unistd.h>
  29 #include <linux/filter.h>
  30
  31 #include "socket-util.h"
  32
  33 #include "dhcp-internal.h"
  34
  35 int dhcp_network_bind_raw_socket(int index, union sockaddr_union *link,
  36                                  uint32_t xid) {
  37         struct sock_filter filter[] = {
  38             BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0),                                 /* A <- packet length */
  39             BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(DHCPPacket), 1, 0),         /* packet >= DHCPPacket ? */
  40             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  41             /* TODO: match ip.version */
  42             BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
  43             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0),                /* IP protocol == UDP ? */
  44             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  45             BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)),    /* A <- UDP destination port */
  46             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_PORT_CLIENT, 1, 0),           /* UDP destination port == DHCP client port ? */
  47             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  48             BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.op)),     /* A <- DHCP op */
  49             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTREPLY, 1, 0),                  /* op == BOOTREPLY ? */
  50             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  51             BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.htype)),  /* A <- DHCP header type */
  52             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0),               /* header type == ARPHRD_ETHER ? */
  53             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  54             BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.hlen)),   /* A <- mac address length */
  55             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHER_ADDR_LEN, 1, 0),             /* address length == ETHER_ADDR_LEN ? */
  56             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  57             BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.xid)),    /* A <- client identifier */
  58             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, xid, 1, 0),                        /* client identifier == xid ? */
  59             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  60             /* TODO: match chaddr */
  61             BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.magic)),  /* A <- DHCP magic cookie */
  62             BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_MAGIC_COOKIE, 1, 0),          /* cookie == DHCP magic cookie ? */
  63             BPF_STMT(BPF_RET + BPF_K, 0),                                          /* ignore */
  64             BPF_STMT(BPF_RET + BPF_K, 65535),                                      /* return all */
  65         };
  66         struct sock_fprog fprog = {
  67             .len = ELEMENTSOF(filter),
  68             .filter = filter
  69         };
  70         _cleanup_close_ int s = -1;
  71         int r, one = 1;
  72
  73         assert(index > 0);
  74         assert(link);
  75
  76         s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
  77         if (s < 0)
  78                 return -errno;
  79
  80         r = setsockopt (s, SOL_PACKET, PACKET_AUXDATA, &one, sizeof(one));
  81         if (r < 0)
  82                 return -errno;
  83
  84         r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
  85         if (r < 0)
  86                 return -errno;
  87
  88         link->ll.sll_family = AF_PACKET;
  89         link->ll.sll_protocol = htons(ETH_P_IP);
  90         link->ll.sll_ifindex =  index;
  91         link->ll.sll_halen = ETH_ALEN;
  92         memset(link->ll.sll_addr, 0xff, ETH_ALEN);
  93
  94         r = bind(s, &link->sa, sizeof(link->ll));
  95         if (r < 0)
  96                 return -errno;
  97
  98         r = s;
  99         s = -1;
 100
 101         return r;
 102 }
 103
 104 int dhcp_network_bind_udp_socket(be32_t address, uint16_t port) {
 105         union sockaddr_union src = {
 106                 .in.sin_family = AF_INET,
 107                 .in.sin_port = htobe16(port),
 108                 .in.sin_addr.s_addr = address,
 109         };
 110         _cleanup_close_ int s = -1;
 111         int r, tos = IPTOS_CLASS_CS6;
 112
 113         s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
 114         if (s < 0)
 115                 return -errno;
 116
 117         r = setsockopt(s, IPPROTO_IP, IP_TOS, &tos, sizeof(tos));
 118         if (r < 0)
 119                 return -errno;
 120
 121         r = bind(s, &src.sa, sizeof(src.in));
 122         if (r < 0)
 123                 return -errno;
 124
 125         r = s;
 126         s = -1;
 127
 128         return r;
 129 }
 130
 131 int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
 132                                  const void *packet, size_t len) {
 133         int r;
 134
 135         assert(link);
 136         assert(packet);
 137         assert(len);
 138
 139         r = sendto(s, packet, len, 0, &link->sa, sizeof(link->ll));
 140         if (r < 0)
 141                 return -errno;
 142
 143         return 0;
 144 }
 145
 146 int dhcp_network_send_udp_socket(int s, be32_t address, uint16_t port,
 147                                  const void *packet, size_t len) {
 148         union sockaddr_union dest = {
 149                 .in.sin_family = AF_INET,
 150                 .in.sin_port = htobe16(port),
 151                 .in.sin_addr.s_addr = address,
 152         };
 153         int r;
 154
 155         assert(s >= 0);
 156         assert(packet);
 157         assert(len);
 158
 159         r = sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in));
 160         if (r < 0)
 161                 return -errno;
 162
 163         return 0;
 164 }