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 <errno.h>
  19 #include <sys/ioctl.h>
  20 #include <sys/socket.h>
  21 #include <sys/types.h>
  22 #include <asm/types.h>
  23 #include <arpa/inet.h>
  24 #include <linux/netlink.h>
  25 #include <linux/rtnetlink.h>
  26 #include <linux/ip.h>
  27 #include <linux/if_arp.h>
  28 #include <linux/if_tunnel.h>
  29 #include <linux/limits.h>
  30
  31 #include "nhrp_protocol.h"
  32 #include "os.h"
  33 #include "netlink.h"
  34
  35 #ifndef HAVE_STRLCPY
  36 size_t strlcpy(char *__restrict dest,
  37                const char *__restrict src, size_t destsize);
  38 #endif
  39
  40 static int nhrp_socket_fd = -1;
  41
  42 int os_socket(void)
  43 {
  44         if (nhrp_socket_fd < 0)
  45                 nhrp_socket_fd =
  46                         socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_NHRP));
  47         return nhrp_socket_fd;
  48 }
  49
  50 int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr,
  51                size_t addrlen, uint16_t protocol)
  52 {
  53         struct sockaddr_ll lladdr;
  54         struct iovec iov = {
  55                 .iov_base = (void *)buf, .iov_len = len,
  56         };
  57         struct msghdr msg = {
  58                 .msg_name = &lladdr,
  59                 .msg_namelen = sizeof(lladdr),
  60                 .msg_iov = &iov,
  61                 .msg_iovlen = 1,
  62         };
  63         int status;
  64
  65         if (addrlen > sizeof(lladdr.sll_addr))
  66                 return -1;
  67
  68         memset(&lladdr, 0, sizeof(lladdr));
  69         lladdr.sll_family = AF_PACKET;
  70         lladdr.sll_protocol = htons(protocol);
  71         lladdr.sll_ifindex = ifindex;
  72         lladdr.sll_halen = addrlen;
  73         memcpy(lladdr.sll_addr, addr, addrlen);
  74
  75         status = sendmsg(os_socket(), &msg, 0);
  76         if (status < 0)
  77                 return -errno;
  78
  79         return status;
  80 }
  81
  82 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr,
  83                size_t *addrlen)
  84 {
  85         struct sockaddr_ll lladdr;
  86         struct iovec iov = {
  87                 .iov_base = buf, .iov_len = *len,
  88         };
  89         struct msghdr msg = {
  90                 .msg_name = &lladdr,
  91                 .msg_namelen = sizeof(lladdr),
  92                 .msg_iov = &iov,
  93                 .msg_iovlen = 1,
  94         };
  95         int r;
  96
  97         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
  98         if (r < 0)
  99                 return r;
 100
 101         *len = r;
 102         *ifindex = lladdr.sll_ifindex;
 103
 104         if (*addrlen <= (size_t)lladdr.sll_addr) {
 105                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
 106                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
 107                         *addrlen = lladdr.sll_halen;
 108                 } else {
 109                         *addrlen = 0;
 110                 }
 111         }
 112
 113         return 0;
 114 }
 115
 116 static int linux_configure_arp(const char *iface, int on)
 117 {
 118         struct ifreq ifr;
 119
 120         strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
 121         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 122                 return -1;
 123
 124         if (on)
 125                 ifr.ifr_flags &= ~IFF_NOARP;
 126         else
 127                 ifr.ifr_flags |= IFF_NOARP;
 128
 129         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 130                 return -1;
 131
 132         return 0;
 133 }
 134
 135 static int linux_icmp_redirect_off(const char *iface)
 136 {
 137         char fname[PATH_MAX];
 138         int fd, ret = -1;
 139
 140         snprintf(fname, sizeof(fname),
 141                  "/proc/sys/net/ipv4/conf/%s/send_redirects", iface);
 142         fd = open(fname, O_WRONLY);
 143         if (fd < 0)
 144                 return -1;
 145         if (write(fd, "0\n", 2) == 2)
 146                 ret = 0;
 147         close(fd);
 148
 149         return ret;
 150 }
 151
 152 int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af)
 153 {
 154         int ret = 0;
 155
 156         switch (af) {
 157         case AF_INET:
 158                 ret |= linux_icmp_redirect_off("all");
 159                 ret |= linux_icmp_redirect_off(ifname);
 160                 break;
 161         }
 162         ret |= linux_configure_arp(ifname, 1);
 163
 164         return ret;
 165 }