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, fd;
  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         fd = os_socket();
  76         if (fd < 0)
  77                 return -1;
  78
  79         status = sendmsg(fd, &msg, 0);
  80         if (status < 0)
  81                 return -errno;
  82
  83         return status;
  84 }
  85
  86 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr,
  87                size_t *addrlen)
  88 {
  89         struct sockaddr_ll lladdr;
  90         struct iovec iov = {
  91                 .iov_base = buf, .iov_len = *len,
  92         };
  93         struct msghdr msg = {
  94                 .msg_name = &lladdr,
  95                 .msg_namelen = sizeof(lladdr),
  96                 .msg_iov = &iov,
  97                 .msg_iovlen = 1,
  98         };
  99         int r;
 100
 101         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
 102         if (r < 0)
 103                 return r;
 104
 105         *len = r;
 106         *ifindex = lladdr.sll_ifindex;
 107
 108         if (*addrlen <= (size_t)lladdr.sll_addr) {
 109                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
 110                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
 111                         *addrlen = lladdr.sll_halen;
 112                 } else {
 113                         *addrlen = 0;
 114                 }
 115         }
 116
 117         return 0;
 118 }
 119
 120 static int linux_configure_arp(const char *iface, int on)
 121 {
 122         struct ifreq ifr;
 123
 124         strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
 125         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 126                 return -1;
 127
 128         if (on)
 129                 ifr.ifr_flags &= ~IFF_NOARP;
 130         else
 131                 ifr.ifr_flags |= IFF_NOARP;
 132
 133         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 134                 return -1;
 135
 136         return 0;
 137 }
 138
 139 static int linux_icmp_redirect_off(const char *iface)
 140 {
 141         char fname[PATH_MAX];
 142         int fd, ret = -1;
 143
 144         snprintf(fname, sizeof(fname),
 145                  "/proc/sys/net/ipv4/conf/%s/send_redirects", iface);
 146         fd = open(fname, O_WRONLY);
 147         if (fd < 0)
 148                 return -1;
 149         if (write(fd, "0\n", 2) == 2)
 150                 ret = 0;
 151         close(fd);
 152
 153         return ret;
 154 }
 155
 156 int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af)
 157 {
 158         int ret = 0;
 159
 160         switch (af) {
 161         case AF_INET:
 162                 ret |= linux_icmp_redirect_off("all");
 163                 ret |= linux_icmp_redirect_off(ifname);
 164                 break;
 165         }
 166         ret |= linux_configure_arp(ifname, 1);
 167
 168         return ret;
 169 }