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