Line data    Source code

       1             : /***
       2             :   This file is part of systemd.
       3             : 
       4             :   Copyright (C) 2014 Axis Communications AB. 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 <linux/filter.h>
      21             : 
      22             : #include "util.h"
      23             : #include "ipv4ll-internal.h"
      24             : 
      25           0 : int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
      26             :                                         const struct ether_arp *arp) {
      27             :         int r;
      28             : 
      29           0 :         assert(arp);
      30           0 :         assert(link);
      31           0 :         assert(fd >= 0);
      32             : 
      33           0 :         r = sendto(fd, arp, sizeof(struct ether_arp), 0, &link->sa, sizeof(link->ll));
      34           0 :         if (r < 0)
      35           0 :                 return -errno;
      36             : 
      37           0 :         return 0;
      38             : }
      39             : 
      40           0 : int arp_network_bind_raw_socket(int ifindex, union sockaddr_union *link) {
      41             : 
      42             :         static const struct sock_filter filter[] = {
      43             :                 BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0),                                         /* A <- packet length */
      44             :                 BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0),           /* packet >= arp packet ? */
      45             :                 BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
      46             :                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
      47             :                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0),                       /* header == ethernet ? */
      48             :                 BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
      49             :                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
      50             :                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0),                       /* protocol == IP ? */
      51             :                 BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
      52             :                 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)),  /* A <- operation */
      53             :                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 0, 1),                      /* protocol == request ? */
      54             :                 BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
      55             :                 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1),                        /* protocol == reply ? */
      56             :                 BPF_STMT(BPF_RET + BPF_K, 65535),                                              /* return all */
      57             :                 BPF_STMT(BPF_RET + BPF_K, 0),                                                  /* ignore */
      58             :         };
      59           0 :         struct sock_fprog fprog = {
      60             :                 .len = ELEMENTSOF(filter),
      61             :                 .filter = (struct sock_filter*) filter
      62             :         };
      63           0 :         _cleanup_close_ int s = -1;
      64             :         int r;
      65             : 
      66           0 :         assert(ifindex > 0);
      67           0 :         assert(link);
      68             : 
      69           0 :         s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
      70           0 :         if (s < 0)
      71           0 :                 return -errno;
      72             : 
      73           0 :         r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
      74           0 :         if (r < 0)
      75           0 :                 return -errno;
      76             : 
      77           0 :         link->ll.sll_family = AF_PACKET;
      78           0 :         link->ll.sll_protocol = htons(ETH_P_ARP);
      79           0 :         link->ll.sll_ifindex = ifindex;
      80           0 :         link->ll.sll_halen = ETH_ALEN;
      81           0 :         memset(link->ll.sll_addr, 0xff, ETH_ALEN);
      82             : 
      83           0 :         r = bind(s, &link->sa, sizeof(link->ll));
      84           0 :         if (r < 0)
      85           0 :                 return -errno;
      86             : 
      87           0 :         r = s;
      88           0 :         s = -1;
      89             : 
      90           0 :         return r;
      91             : }