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