From 16fe3b976a5c0d42817c4d8ed886efbc0759922f Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Fri, 28 Sep 2012 16:53:51 +0000
Subject: -do not close stdin/stdout for standard system progs

---
 src/dns/gnunet-helper-dns.c | 48 ++++++++++++++++++++++++++++++++++++++++++++-
 src/pt/test_gns_vpn.c       | 48 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 88 insertions(+), 8 deletions(-)

(limited to 'src')

diff --git a/src/dns/gnunet-helper-dns.c b/src/dns/gnunet-helper-dns.c
index 1fb1dcfbb..c230ec544 100644
--- a/src/dns/gnunet-helper-dns.c
+++ b/src/dns/gnunet-helper-dns.c
@@ -154,6 +154,33 @@ signal_handler (int signal)
 }
 
 
+/**
+ * Open '/dev/null' and make the result the given
+ * file descriptor.
+ *
+ * @param target_fd desired FD to point to /dev/null
+ * @param flags open flags (O_RDONLY, O_WRONLY)
+ */
+static void
+open_dev_null (int target_fd,
+	       int flags)
+{
+  int fd;
+
+  fd = open ("/dev/null", flags);
+  if (-1 == fd)
+    abort ();
+  if (fd == target_fd)
+    return;
+  if (-1 == dup2 (fd, target_fd))
+  {    
+    (void) close (fd);
+    abort ();
+  }
+  (void) close (fd);
+}
+
+
 /**
  * Run the given command and wait for it to complete.
  * 
@@ -183,7 +210,9 @@ fork_and_exec (const char *file,
     /* close stdin/stdout to not cause interference
        with the helper's main protocol! */
     (void) close (0); 
+    open_dev_null (0, O_RDONLY);
     (void) close (1); 
+    open_dev_null (1, O_WRONLY);
     (void) execv (file, cmd);
     /* can only get here on error */
     fprintf (stderr, 
@@ -683,6 +712,7 @@ PROCESS_BUFFER:
  *         25-39 failed to drop privs and then failed to undo some changes to routing table
  *         40 failed to regain privs
  *         41-55 failed to regain prisv and then failed to undo some changes to routing table
+ *         254 insufficient priviledges
  *         255 failed to handle kill signal properly
  */
 int
@@ -692,6 +722,7 @@ main (int argc, char *const*argv)
   char dev[IFNAMSIZ];
   char mygid[32];
   int fd_tun;
+  uid_t uid;
 
   if (6 != argc)
   {
@@ -699,6 +730,22 @@ main (int argc, char *const*argv)
     return 1;
   }
 
+  /* assert privs so we can modify the firewall rules! */
+  uid = getuid ();
+#ifdef HAVE_SETRESUID
+  if (0 != setresuid (uid, 0, 0))
+  {
+    fprintf (stderr, "Failed to setresuid to root: %s\n", strerror (errno));
+    return 254;
+  }
+#else
+  if (0 != seteuid (0)) 
+  {
+    fprintf (stderr, "Failed to seteuid back to root: %s\n", strerror (errno));
+    return 254;
+  }
+#endif
+
   /* verify that the binaries were care about are executable */
   if (0 == access ("/sbin/iptables", X_OK))
     sbin_iptables = "/sbin/iptables";
@@ -899,7 +946,6 @@ main (int argc, char *const*argv)
 
   /* drop privs *except* for the saved UID; this is not perfect, but better
      than doing nothing */
-  uid_t uid = getuid ();
 #ifdef HAVE_SETRESUID
   if (0 != setresuid (uid, uid, 0))
   {
diff --git a/src/pt/test_gns_vpn.c b/src/pt/test_gns_vpn.c
index 9789ce7d9..faff03cf3 100644
--- a/src/pt/test_gns_vpn.c
+++ b/src/pt/test_gns_vpn.c
@@ -239,6 +239,7 @@ curl_main ()
 					      NULL);  
 }
 
+
 static void
 start_curl (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
@@ -261,12 +262,14 @@ start_curl (void *cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
   curl_main ();
 }
 
+
 static void
 disco_ns (void* cls, const struct GNUNET_SCHEDULER_TaskContext *tc)
 {
   GNUNET_NAMESTORE_disconnect (namestore);
 }
 
+
 /**
  * Callback invoked from the namestore service once record is
  * created.
@@ -354,6 +357,7 @@ mhd_main ()
 					     NULL);  
 }
 
+
 static void
 run (void *cls,
      const struct GNUNET_CONFIGURATION_Handle *cfg,
@@ -437,6 +441,33 @@ test_af (int af)
 }
 
 
+/**
+ * Open '/dev/null' and make the result the given
+ * file descriptor.
+ *
+ * @param target_fd desired FD to point to /dev/null
+ * @param flags open flags (O_RDONLY, O_WRONLY)
+ */
+static void
+open_dev_null (int target_fd,
+	       int flags)
+{
+  int fd;
+
+  fd = open ("/dev/null", flags);
+  if (-1 == fd)
+    abort ();
+  if (fd == target_fd)
+    return;
+  if (-1 == dup2 (fd, target_fd))
+  {    
+    (void) close (fd);
+    abort ();
+  }
+  (void) close (fd);
+}
+
+
 /**
  * Run the given command and wait for it to complete.
  * 
@@ -466,7 +497,9 @@ fork_and_exec (const char *file,
     /* close stdin/stdout to not cause interference
        with the helper's main protocol! */
     (void) close (0); 
+    open_dev_null (0, O_RDONLY);
     (void) close (1); 
+    open_dev_null (1, O_WRONLY);
     (void) execv (file, cmd);
     /* can only get here on error */
     fprintf (stderr, 
@@ -515,7 +548,7 @@ main (int argc, char *const *argv)
   if (0 != fork_and_exec (sbin_iptables, iptables_args))
   {
     fprintf (stderr,
-             "IPtables not available, Skipping.\n");
+             "Failed to run `iptables -t mangle -L -v'. Skipping test.\n");
     return 0;
   }
 
@@ -529,12 +562,13 @@ main (int argc, char *const *argv)
     return 0;
   }
 
-  if ( (GNUNET_YES !=
-	GNUNET_OS_check_helper_binary ("gnunet-helper-vpn")) ||
-       (GNUNET_YES !=
-	GNUNET_OS_check_helper_binary ("gnunet-helper-exit")) ||
-       (GNUNET_YES !=
-  GNUNET_OS_check_helper_binary ("gnunet-helper-dns")))
+  if ( (0 != geteuid ()) &&
+       ( (GNUNET_YES !=
+	  GNUNET_OS_check_helper_binary ("gnunet-helper-vpn")) ||
+	 (GNUNET_YES !=
+	  GNUNET_OS_check_helper_binary ("gnunet-helper-exit")) ||
+	 (GNUNET_YES !=
+	  GNUNET_OS_check_helper_binary ("gnunet-helper-dns"))) )
   {
     fprintf (stderr,
 	     "WARNING: gnunet-helper-{exit,vpn,dns} binaries in $PATH are not SUID, refusing to run test (as it would have to fail).\n");
-- 
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