sysdeps/unix/sysv/linux/arm/check_pf.c

   1 /* Determine protocol families for which interfaces exist.  Linux version.
   2    Copyright (C) 2003, 2006, 2007 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22 #include <ifaddrs.h>
  23 #include <netdb.h>
  24 #include <stddef.h>
  25 #include <string.h>
  26 #include <time.h>
  27 #include <unistd.h>
  28 #include <sys/socket.h>
  29
  30 #include <asm/types.h>
  31 #include <linux/netlink.h>
  32 #include <linux/rtnetlink.h>
  33
  34 #include <not-cancel.h>
  35 #include <kernel-features.h>
  36
  37
  38 #ifndef IFA_F_TEMPORARY
  39 # define IFA_F_TEMPORARY IFA_F_SECONDARY
  40 #endif
  41 #ifndef IFA_F_HOMEADDRESS
  42 # define IFA_F_HOMEADDRESS 0
  43 #endif
  44
  45
  46 static int
  47 make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6,
  48               struct in6addrinfo **in6ai, size_t *in6ailen)
  49 {
  50   struct req
  51   {
  52     struct nlmsghdr nlh;
  53     struct rtgenmsg g;
  54   } req;
  55   struct sockaddr_nl nladdr;
  56
  57   /* struct rtgenmsg consists of a single byte but the ARM ABI rounds
  58      it up to a word.  Clear the padding explicitly here.  */
  59   assert (sizeof (req.g) == 4);
  60   memset (&req.g, '\0', sizeof (req.g));
  61
  62   req.nlh.nlmsg_len = sizeof (req);
  63   req.nlh.nlmsg_type = RTM_GETADDR;
  64   req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
  65   req.nlh.nlmsg_pid = 0;
  66   req.nlh.nlmsg_seq = time (NULL);
  67   req.g.rtgen_family = AF_UNSPEC;
  68
  69   memset (&nladdr, '\0', sizeof (nladdr));
  70   nladdr.nl_family = AF_NETLINK;
  71
  72 #ifdef PAGE_SIZE
  73   /* Help the compiler optimize out the malloc call if PAGE_SIZE
  74      is constant and smaller or equal to PTHREAD_STACK_MIN/4.  */
  75   const size_t buf_size = PAGE_SIZE;
  76 #else
  77   const size_t buf_size = __getpagesize ();
  78 #endif
  79   bool use_malloc = false;
  80   char *buf;
  81
  82   if (__libc_use_alloca (buf_size))
  83     buf = alloca (buf_size);
  84   else
  85     {
  86       buf = malloc (buf_size);
  87       if (buf != NULL)
  88         use_malloc = true;
  89       else
  90         goto out_fail;
  91     }
  92
  93   struct iovec iov = { buf, buf_size };
  94
  95   if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
  96                                     (struct sockaddr *) &nladdr,
  97                                     sizeof (nladdr))) < 0)
  98     goto out_fail;
  99
 100   *seen_ipv4 = false;
 101   *seen_ipv6 = false;
 102
 103   bool done = false;
 104   struct in6ailist
 105   {
 106     struct in6addrinfo info;
 107     struct in6ailist *next;
 108   } *in6ailist = NULL;
 109   size_t in6ailistlen = 0;
 110
 111   do
 112     {
 113       struct msghdr msg =
 114         {
 115           (void *) &nladdr, sizeof (nladdr),
 116           &iov, 1,
 117           NULL, 0,
 118           0
 119         };
 120
 121       ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
 122       if (read_len < 0)
 123         goto out_fail;
 124
 125       if (msg.msg_flags & MSG_TRUNC)
 126         goto out_fail;
 127
 128       struct nlmsghdr *nlmh;
 129       for (nlmh = (struct nlmsghdr *) buf;
 130            NLMSG_OK (nlmh, (size_t) read_len);
 131            nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
 132         {
 133           if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid
 134               || nlmh->nlmsg_seq != req.nlh.nlmsg_seq)
 135             continue;
 136
 137           if (nlmh->nlmsg_type == RTM_NEWADDR)
 138             {
 139               struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlmh);
 140               struct rtattr *rta = IFA_RTA (ifam);
 141               size_t len = nlmh->nlmsg_len - NLMSG_LENGTH (sizeof (*ifam));
 142
 143               switch (ifam->ifa_family)
 144                 {
 145                   const void *local;
 146                   const void *address;
 147
 148                 case AF_INET:
 149                   local = NULL;
 150                   address = NULL;
 151                   while (RTA_OK (rta, len))
 152                     {
 153                       switch (rta->rta_type)
 154                         {
 155                         case IFA_LOCAL:
 156                           local = RTA_DATA (rta);
 157                           break;
 158
 159                         case IFA_ADDRESS:
 160                           address = RTA_DATA (rta);
 161                           goto out_v4;
 162                         }
 163
 164                       rta = RTA_NEXT (rta, len);
 165                     }
 166
 167                   if (local != NULL)
 168                     {
 169                     out_v4:
 170                       if (*(const in_addr_t *) (address ?: local)
 171                           != htonl (INADDR_LOOPBACK))
 172                         *seen_ipv4 = true;
 173                     }
 174                   break;
 175
 176                 case AF_INET6:
 177                   local = NULL;
 178                   address = NULL;
 179                   while (RTA_OK (rta, len))
 180                     {
 181                       switch (rta->rta_type)
 182                         {
 183                         case IFA_LOCAL:
 184                           local = RTA_DATA (rta);
 185                           break;
 186
 187                         case IFA_ADDRESS:
 188                           address = RTA_DATA (rta);
 189                           goto out_v6;
 190                         }
 191
 192                       rta = RTA_NEXT (rta, len);
 193                     }
 194
 195                   if (local != NULL)
 196                     {
 197                     out_v6:
 198                       if (!IN6_IS_ADDR_LOOPBACK (address ?: local))
 199                         *seen_ipv6 = true;
 200                     }
 201
 202                   if (ifam->ifa_flags & (IFA_F_DEPRECATED
 203                                          | IFA_F_TEMPORARY
 204                                          | IFA_F_HOMEADDRESS))
 205                     {
 206                       struct in6ailist *newp = alloca (sizeof (*newp));
 207                       newp->info.flags = (((ifam->ifa_flags & IFA_F_DEPRECATED)
 208                                            ? in6ai_deprecated : 0)
 209                                           | ((ifam->ifa_flags
 210                                               & IFA_F_TEMPORARY)
 211                                              ? in6ai_temporary : 0)
 212                                           | ((ifam->ifa_flags
 213                                               & IFA_F_HOMEADDRESS)
 214                                              ? in6ai_homeaddress : 0));
 215                       memcpy (newp->info.addr, address ?: local,
 216                               sizeof (newp->info.addr));
 217                       newp->next = in6ailist;
 218                       in6ailist = newp;
 219                       ++in6ailistlen;
 220                     }
 221                   break;
 222                 default:
 223                   /* Ignore.  */
 224                   break;
 225                 }
 226             }
 227           else if (nlmh->nlmsg_type == NLMSG_DONE)
 228             /* We found the end, leave the loop.  */
 229             done = true;
 230         }
 231     }
 232   while (! done);
 233
 234   close_not_cancel_no_status (fd);
 235
 236   if (*seen_ipv6 && in6ailist != NULL)
 237     {
 238       *in6ai = malloc (in6ailistlen * sizeof (**in6ai));
 239       if (*in6ai == NULL)
 240         goto out_fail;
 241
 242       *in6ailen = in6ailistlen;
 243
 244       do
 245         {
 246           (*in6ai)[--in6ailistlen] = in6ailist->info;
 247           in6ailist = in6ailist->next;
 248         }
 249       while (in6ailist != NULL);
 250     }
 251
 252   if (use_malloc)
 253     free (buf);
 254   return 0;
 255
 256 out_fail:
 257   if (use_malloc)
 258     free (buf);
 259   return -1;
 260 }
 261
 262
 263 /* We don't know if we have NETLINK support compiled in in our
 264    Kernel.  */
 265 #if __ASSUME_NETLINK_SUPPORT == 0
 266 /* Define in ifaddrs.h.  */
 267 extern int __no_netlink_support attribute_hidden;
 268 #else
 269 # define __no_netlink_support 0
 270 #endif
 271
 272
 273 void
 274 attribute_hidden
 275 __check_pf (bool *seen_ipv4, bool *seen_ipv6,
 276             struct in6addrinfo **in6ai, size_t *in6ailen)
 277 {
 278   *in6ai = NULL;
 279   *in6ailen = 0;
 280
 281   if (! __no_netlink_support)
 282     {
 283       int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 284
 285       struct sockaddr_nl nladdr;
 286       memset (&nladdr, '\0', sizeof (nladdr));
 287       nladdr.nl_family = AF_NETLINK;
 288
 289       socklen_t addr_len = sizeof (nladdr);
 290
 291       if (fd >= 0
 292           && __bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
 293           && __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) == 0
 294           && make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6,
 295                            in6ai, in6ailen) == 0)
 296         /* It worked.  */
 297         return;
 298
 299       if (fd >= 0)
 300         __close (fd);
 301
 302 #if __ASSUME_NETLINK_SUPPORT == 0
 303       /* Remember that there is no netlink support.  */
 304       __no_netlink_support = 1;
 305 #else
 306       /* We cannot determine what interfaces are available.  Be
 307          pessimistic.  */
 308       *seen_ipv4 = true;
 309       *seen_ipv6 = true;
 310 #endif
 311     }
 312
 313 #if __ASSUME_NETLINK_SUPPORT == 0
 314   /* No netlink.  Get the interface list via getifaddrs.  */
 315   struct ifaddrs *ifa = NULL;
 316   if (getifaddrs (&ifa) != 0)
 317     {
 318       /* We cannot determine what interfaces are available.  Be
 319          pessimistic.  */
 320       *seen_ipv4 = true;
 321       *seen_ipv6 = true;
 322       return;
 323     }
 324
 325   struct ifaddrs *runp;
 326   for (runp = ifa; runp != NULL; runp = runp->ifa_next)
 327     if (runp->ifa_addr->sa_family == PF_INET)
 328       *seen_ipv4 = true;
 329     else if (runp->ifa_addr->sa_family == PF_INET6)
 330       *seen_ipv6 = true;
 331
 332   (void) freeifaddrs (ifa);
 333 #endif
 334 }