glibc/glibc-bindresvport-blacklist.diff

Index: glibc-2.32/inet/bindresvport.c
===================================================================
--- glibc-2.32.orig/inet/bindresvport.c
+++ glibc-2.32/inet/bindresvport.c
@@ -29,6 +29,9 @@
  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.h>
 #include <errno.h>
 #include <unistd.h>
 #include <string.h>
@@ -42,6 +45,93 @@
  */
 __libc_lock_define_initialized (static, lock);
 
+#define STARTPORT 600
+#define LOWPORT 512
+#define ENDPORT (IPPORT_RESERVED - 1)
+#define NPORTS	(ENDPORT - STARTPORT + 1)
+
+/* Read the file /etc/rpc.blacklisted, so that we don't bind to these
+   ports.  */
+
+static int blacklist_read;
+static int *list;
+static int list_size = 0;
+
+static void
+load_blacklist (void)
+{
+  FILE *fp;
+  char *buf = NULL;
+  size_t buflen = 0;
+  int size = 0, ptr = 0;
+
+  __libc_lock_lock (lock);
+  if (blacklist_read)
+    goto unlock;
+  blacklist_read = 1;
+
+  fp = fopen ("/etc/bindresvport.blacklist", "r");
+  if (fp == NULL)
+    goto unlock;
+
+  while (!feof_unlocked (fp))
+    {
+      unsigned long port;
+      char *tmp, *cp;
+      ssize_t n = __getline (&buf, &buflen, fp);
+      if (n < 1)
+        break;
+
+      cp = buf;
+      /* Remove comments.  */
+      tmp = strchr (cp, '#');
+      if (tmp)
+        *tmp = '\0';
+      /* Remove spaces and tabs.  */
+      while (isspace ((unsigned char) *cp))
+        ++cp;
+      /* Ignore empty lines.  */
+      if (*cp == '\0')
+        continue;
+      if (cp[strlen (cp) - 1] == '\n')
+        cp[strlen (cp) - 1] = '\0';
+
+      port = strtoul (cp, &tmp, 0);
+      while (isspace ((unsigned char) *tmp))
+        ++tmp;
+      if (*tmp != '\0' || (port == ULONG_MAX && errno == ERANGE))
+	continue;
+
+      /* Don't bother with out-of-range ports.  */
+      if (port < LOWPORT || port > ENDPORT)
+        continue;
+
+      if (ptr >= size)
+	{
+	  size += 10;
+	  int *new_list = realloc (list, size * sizeof (int));
+	  if (new_list == NULL)
+	    {
+	      free (list);
+	      list = NULL;
+	      free (buf);
+	      goto unlock;
+	    }
+	  list = new_list;
+	}
+
+      list[ptr++] = port;
+    }
+
+  fclose (fp);
+  free (buf);
+  list_size = ptr;
+
+ unlock:
+  __libc_lock_unlock (lock);
+}
+
+
 /*
  * Bind a socket to a privileged IP port
  */
@@ -52,12 +142,11 @@ bindresvport (int sd, struct sockaddr_in
   struct sockaddr_in myaddr;
   int i;
 
-#define STARTPORT 600
-#define LOWPORT 512
-#define ENDPORT (IPPORT_RESERVED - 1)
-#define NPORTS	(ENDPORT - STARTPORT + 1)
   static short startport = STARTPORT;
 
+  if (!blacklist_read)
+    load_blacklist ();
+
   if (sin == (struct sockaddr_in *) 0)
     {
       sin = &myaddr;
@@ -75,6 +164,7 @@ bindresvport (int sd, struct sockaddr_in
       port = (__getpid () % NPORTS) + STARTPORT;
     }
 
+  __set_errno (EADDRINUSE);
   /* Initialize to make gcc happy.  */
   int res = -1;
 
@@ -86,12 +176,22 @@ bindresvport (int sd, struct sockaddr_in
  again:
   for (i = 0; i < nports; ++i)
     {
-      sin->sin_port = htons (port++);
-      if (port > endport)
-	port = startport;
+      int j;
+
+      sin->sin_port = htons (port);
+
+      /* Check that this port is not blacklisted.  */
+      for (j = 0; j < list_size; j++)
+	if (port == list[j])
+	  goto try_next_port;
+
       res = __bind (sd, sin, sizeof (struct sockaddr_in));
       if (res >= 0 || errno != EADDRINUSE)
 	break;
+
+    try_next_port:
+      if (++port > endport)
+	port = startport;
     }
 
   if (i == nports && startport != LOWPORT)