* interface. It will force traffic to be in 'ad-hoc' mode, use the
* proper MAC address of the WLAN interface and use a GNUnet-specific
* SSID (and a GNUnet-specific SNAP header). It only takes a single
- * argument, which is the name of the interface to use. Since it uses
- * RAW sockets, it must be installed SUID or run as 'root'. In order
- * to keep the security risk of the resulting SUID binary minimal, the
- * program ONLY opens the RAW socket with root privileges, then drops
- * them and only then starts to process command line arguments. The
- * code also does not link against any shared libraries (except libc)
- * and is strictly minimal (except for checking for errors). The
- * following list of people have reviewed this code and considered it
- * safe since the last modification (if you reviewed it, please have
- * your name added to the list):
+ * argument, which is the name of the WLAN interface to use. The
+ * program detects if the interface is not a WLAN interface and exits
+ * with an error in that case.
*
- * - Christian Grothoff (Mar 16th 2012)
+ * Once initialized, the program will first send a 'struct
+ * GNUNET_TRANSPORT_WLAN_HelperControlMessage' to 'stdout'. That
+ * message contains the MAC address of the WLAN interface. It will
+ * then read messages from the WLAN interface and send them together
+ * with performance information as 'struct
+ * GNUNET_TRANSPORT_WLAN_RadiotapReceiveMessage' messages to 'stdout'.
+ * Furthermore, it will read a stream of messages from 'stdin' that
+ * have the format from 'struct
+ * GNUNET_TRANSPORT_WLAN_RadiotapSendMessage'. Those messages will
+ * then be sent via the WLAN interface; however, the sender MAC
+ * address will be forced to be the correct address from our WLAN
+ * card. If 'stdin' closes, receiving from the WLAN interface will
+ * continue. If 'stdout' causes a SIGPIPE, the process dies from the
+ * signal. Errors cause an error message to be reported to 'stderr',
+ * in most cases the process also exits (with status code '1'). The
+ * program never terminates normally; it is safe to kill the
+ * process with SIGTERM or SIGKILL at any time.
+ *
+ * Since it uses RAW sockets, the binary must be installed SUID or run
+ * as 'root'. In order to keep the security risk of the resulting
+ * SUID binary minimal, the program ONLY opens the RAW socket with
+ * root privileges, then drops them and only then starts to process
+ * command line arguments. The code also does not link against any
+ * shared libraries (except libc) and is strictly minimal (except for
+ * checking for errors). The following list of people have reviewed
+ * this code and considered it safe since the last modification (if
+ * you reviewed it, please have your name added to the list):
+ *
+ * - Christian Grothoff (Apr 3rd 2012)
*/
/*-
sendsize = ntohs (hdr->size);
if ( (sendsize <
sizeof (struct GNUNET_TRANSPORT_WLAN_RadiotapSendMessage)) ||
- (GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA != ntohs (hdr->type)) )
+ (GNUNET_MESSAGE_TYPE_WLAN_DATA_TO_HELPER != ntohs (hdr->type)) )
{
fprintf (stderr, "Received malformed message\n");
exit (1);
sendsize -= (sizeof (struct GNUNET_TRANSPORT_WLAN_RadiotapSendMessage) - sizeof (struct GNUNET_TRANSPORT_WLAN_Ieee80211Frame));
if (MAXLINE < sendsize)
{
- fprintf (stderr, "Function stdin_send_hw: Packet too big for buffer\n");
+ fprintf (stderr, "Packet too big for buffer\n");
exit (1);
}
header = (const struct GNUNET_TRANSPORT_WLAN_RadiotapSendMessage *) hdr;
struct MessageStreamTokenizer *stdin_mst;
int raw_eno;
+ /* make use of SGID capabilities on POSIX */
memset (&dev, 0, sizeof (dev));
dev.fd_raw = socket (PF_PACKET, SOCK_RAW, htons (ETH_P_ALL));
raw_eno = errno; /* remember for later */
- /* drop privs */
- {
- uid_t uid = getuid ();
-#ifdef HAVE_SETRESUID
- if (0 != setresuid (uid, uid, uid))
- {
- fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
- if (-1 != dev.fd_raw)
- (void) close (dev.fd_raw);
- return 1;
- }
-#else
- if (0 != (setuid (uid) | seteuid (uid)))
- {
- fprintf (stderr, "Failed to setuid: %s\n", strerror (errno));
- if (-1 != dev.fd_raw)
- (void) close (dev.fd_raw);
- return 1;
- }
- }
-#endif
-
/* now that we've dropped root rights, we can do error checking */
if (2 != argc)
{
return 1;
}
+ /* drop privs */
+ {
+ uid_t uid = getuid ();
+#ifdef HAVE_SETRESUID
+ if (0 != setresuid (uid, uid, uid))
+ {
+ fprintf (stderr, "Failed to setresuid: %s\n", strerror (errno));
+ if (-1 != dev.fd_raw)
+ (void) close (dev.fd_raw);
+ return 1;
+ }
+#else
+ if (0 != (setuid (uid) | seteuid (uid)))
+ {
+ fprintf (stderr, "Failed to setuid: %s\n", strerror (errno));
+ if (-1 != dev.fd_raw)
+ (void) close (dev.fd_raw);
+ return 1;
+ }
+ }
+#endif
+
+
/* send MAC address of the WLAN interface to STDOUT first */
{
struct GNUNET_TRANSPORT_WLAN_HelperControlMessage macmsg;
+ sizeof (struct GNUNET_TRANSPORT_WLAN_RadiotapReceiveMessage)
- sizeof (struct GNUNET_TRANSPORT_WLAN_Ieee80211Frame);
rrm->header.size = htons (write_std.size);
- rrm->header.type = htons (GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA);
+ rrm->header.type = htons (GNUNET_MESSAGE_TYPE_WLAN_DATA_FROM_HELPER);
}
}
}
projects / oweals / gnunet.git / blobdiff