nhrpd/linux.c

   1 /* NHRP daemon Linux specific glue
   2  * Copyright (c) 2014-2015 Timo Teräs
   3  *
   4  * This file is free software: you may copy, redistribute and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  */
   9
  10 #ifdef HAVE_CONFIG_H
  11 #include "config.h"
  12 #endif
  13
  14 #include <fcntl.h>
  15 #include <stdio.h>
  16 #include <unistd.h>
  17 #include <string.h>
  18 #include <sys/ioctl.h>
  19 #include <sys/socket.h>
  20 #include <sys/types.h>
  21 #include <asm/types.h>
  22 #include <arpa/inet.h>
  23 #include <linux/netlink.h>
  24 #include <linux/rtnetlink.h>
  25 #include <linux/ip.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/if_tunnel.h>
  28
  29 #include "nhrp_protocol.h"
  30 #include "os.h"
  31 #include "netlink.h"
  32
  33 static int nhrp_socket_fd = -1;
  34
  35 int os_socket(void)
  36 {
  37         if (nhrp_socket_fd < 0)
  38                 nhrp_socket_fd =
  39                         socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_NHRP));
  40         return nhrp_socket_fd;
  41 }
  42
  43 int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr,
  44                size_t addrlen)
  45 {
  46         struct sockaddr_ll lladdr;
  47         struct iovec iov = {
  48                 .iov_base = (void *)buf, .iov_len = len,
  49         };
  50         struct msghdr msg = {
  51                 .msg_name = &lladdr,
  52                 .msg_namelen = sizeof(lladdr),
  53                 .msg_iov = &iov,
  54                 .msg_iovlen = 1,
  55         };
  56         int status;
  57
  58         if (addrlen > sizeof(lladdr.sll_addr))
  59                 return -1;
  60
  61         memset(&lladdr, 0, sizeof(lladdr));
  62         lladdr.sll_family = AF_PACKET;
  63         lladdr.sll_protocol = htons(ETH_P_NHRP);
  64         lladdr.sll_ifindex = ifindex;
  65         lladdr.sll_halen = addrlen;
  66         memcpy(lladdr.sll_addr, addr, addrlen);
  67
  68         status = sendmsg(nhrp_socket_fd, &msg, 0);
  69         if (status < 0)
  70                 return -1;
  71
  72         return 0;
  73 }
  74
  75 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr,
  76                size_t *addrlen)
  77 {
  78         struct sockaddr_ll lladdr;
  79         struct iovec iov = {
  80                 .iov_base = buf, .iov_len = *len,
  81         };
  82         struct msghdr msg = {
  83                 .msg_name = &lladdr,
  84                 .msg_namelen = sizeof(lladdr),
  85                 .msg_iov = &iov,
  86                 .msg_iovlen = 1,
  87         };
  88         int r;
  89
  90         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
  91         if (r < 0)
  92                 return r;
  93
  94         *len = r;
  95         *ifindex = lladdr.sll_ifindex;
  96
  97         if (*addrlen <= (size_t)lladdr.sll_addr) {
  98                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
  99                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
 100                         *addrlen = lladdr.sll_halen;
 101                 } else {
 102                         *addrlen = 0;
 103                 }
 104         }
 105
 106         return 0;
 107 }
 108
 109 static int linux_configure_arp(const char *iface, int on)
 110 {
 111         struct ifreq ifr;
 112
 113         strncpy(ifr.ifr_name, iface, IFNAMSIZ - 1);
 114         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 115                 return -1;
 116
 117         if (on)
 118                 ifr.ifr_flags &= ~IFF_NOARP;
 119         else
 120                 ifr.ifr_flags |= IFF_NOARP;
 121
 122         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 123                 return -1;
 124
 125         return 0;
 126 }
 127
 128 static int linux_icmp_redirect_off(const char *iface)
 129 {
 130         char fname[256];
 131         int fd, ret = -1;
 132
 133         sprintf(fname, "/proc/sys/net/ipv4/conf/%s/send_redirects", iface);
 134         fd = open(fname, O_WRONLY);
 135         if (fd < 0)
 136                 return -1;
 137         if (write(fd, "0\n", 2) == 2)
 138                 ret = 0;
 139         close(fd);
 140
 141         return ret;
 142 }
 143
 144 int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af)
 145 {
 146         int ret = 0;
 147
 148         switch (af) {
 149         case AF_INET:
 150                 ret |= linux_icmp_redirect_off("all");
 151                 ret |= linux_icmp_redirect_off(ifname);
 152                 break;
 153         }
 154         ret |= linux_configure_arp(ifname, 1);
 155         ret |= netlink_configure_arp(ifindex, af);
 156
 157         return ret;
 158 }