nhrpd/linux.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* NHRP daemon Linux specific glue
   3  * Copyright (c) 2014-2015 Timo Teräs
   4  */
   5
   6 #include "zebra.h"
   7
   8 #include <errno.h>
   9 #include <linux/if_packet.h>
  10
  11 #include "nhrp_protocol.h"
  12 #include "os.h"
  13
  14 #ifndef HAVE_STRLCPY
  15 size_t strlcpy(char *__restrict dest,
  16                const char *__restrict src, size_t destsize);
  17 #endif
  18
  19 static int nhrp_socket_fd = -1;
  20
  21 int os_socket(void)
  22 {
  23         if (nhrp_socket_fd < 0)
  24                 nhrp_socket_fd =
  25                         socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_NHRP));
  26         return nhrp_socket_fd;
  27 }
  28
  29 int os_sendmsg(const uint8_t *buf, size_t len, int ifindex, const uint8_t *addr,
  30                size_t addrlen, uint16_t protocol)
  31 {
  32         struct sockaddr_ll lladdr;
  33         struct iovec iov = {
  34                 .iov_base = (void *)buf, .iov_len = len,
  35         };
  36         struct msghdr msg = {
  37                 .msg_name = &lladdr,
  38                 .msg_namelen = sizeof(lladdr),
  39                 .msg_iov = &iov,
  40                 .msg_iovlen = 1,
  41         };
  42         int status, fd;
  43
  44         if (addrlen > sizeof(lladdr.sll_addr))
  45                 return -1;
  46
  47         memset(&lladdr, 0, sizeof(lladdr));
  48         lladdr.sll_family = AF_PACKET;
  49         lladdr.sll_protocol = htons(protocol);
  50         lladdr.sll_ifindex = ifindex;
  51         lladdr.sll_halen = addrlen;
  52         memcpy(lladdr.sll_addr, addr, addrlen);
  53
  54         fd = os_socket();
  55         if (fd < 0)
  56                 return -1;
  57
  58         status = sendmsg(fd, &msg, 0);
  59         if (status < 0)
  60                 return -errno;
  61
  62         return status;
  63 }
  64
  65 int os_recvmsg(uint8_t *buf, size_t *len, int *ifindex, uint8_t *addr,
  66                size_t *addrlen)
  67 {
  68         struct sockaddr_ll lladdr;
  69         struct iovec iov = {
  70                 .iov_base = buf, .iov_len = *len,
  71         };
  72         struct msghdr msg = {
  73                 .msg_name = &lladdr,
  74                 .msg_namelen = sizeof(lladdr),
  75                 .msg_iov = &iov,
  76                 .msg_iovlen = 1,
  77         };
  78         int r;
  79
  80         r = recvmsg(nhrp_socket_fd, &msg, MSG_DONTWAIT);
  81         if (r < 0)
  82                 return r;
  83
  84         *len = r;
  85         *ifindex = lladdr.sll_ifindex;
  86
  87         if (*addrlen <= (size_t)lladdr.sll_addr) {
  88                 if (memcmp(lladdr.sll_addr, "\x00\x00\x00\x00", 4) != 0) {
  89                         memcpy(addr, lladdr.sll_addr, lladdr.sll_halen);
  90                         *addrlen = lladdr.sll_halen;
  91                 } else {
  92                         *addrlen = 0;
  93                 }
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int linux_configure_arp(const char *iface, int on)
 100 {
 101         struct ifreq ifr;
 102
 103         strlcpy(ifr.ifr_name, iface, IFNAMSIZ);
 104         if (ioctl(nhrp_socket_fd, SIOCGIFFLAGS, &ifr))
 105                 return -1;
 106
 107         if (on)
 108                 ifr.ifr_flags &= ~IFF_NOARP;
 109         else
 110                 ifr.ifr_flags |= IFF_NOARP;
 111
 112         if (ioctl(nhrp_socket_fd, SIOCSIFFLAGS, &ifr))
 113                 return -1;
 114
 115         return 0;
 116 }
 117
 118 static int linux_icmp_redirect_off(const char *iface)
 119 {
 120         char fname[PATH_MAX];
 121         int fd, ret = -1;
 122
 123         snprintf(fname, sizeof(fname),
 124                  "/proc/sys/net/ipv4/conf/%s/send_redirects", iface);
 125         fd = open(fname, O_WRONLY);
 126         if (fd < 0)
 127                 return -1;
 128         if (write(fd, "0\n", 2) == 2)
 129                 ret = 0;
 130         close(fd);
 131
 132         return ret;
 133 }
 134
 135 int os_configure_dmvpn(unsigned int ifindex, const char *ifname, int af)
 136 {
 137         int ret = 0;
 138
 139         switch (af) {
 140         case AF_INET:
 141                 ret |= linux_icmp_redirect_off("all");
 142                 ret |= linux_icmp_redirect_off(ifname);
 143                 break;
 144         }
 145         ret |= linux_configure_arp(ifname, 1);
 146
 147         return ret;
 148 }