Initial import

1 files changed, 553 insertions, 0 deletions

diff --git a/openvpn/src/plugins/down-root/down-root.c b/openvpn/src/plugins/down-root/down-root.c
new file mode 100644
index 00000000..fced23be
--- /dev/null
+++ b/openvpn/src/plugins/down-root/down-root.c
@@ -0,0 +1,553 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/*
+ * OpenVPN plugin module to do privileged down-script execution.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <syslog.h>
+
+#include "openvpn-plugin.h"
+
+#define DEBUG(verb) ((verb) >= 7)
+
+/* Command codes for foreground -> background communication */
+#define COMMAND_RUN_SCRIPT 0
+#define COMMAND_EXIT       1
+
+/* Response codes for background -> foreground communication */
+#define RESPONSE_INIT_SUCCEEDED   10
+#define RESPONSE_INIT_FAILED      11
+#define RESPONSE_SCRIPT_SUCCEEDED 12
+#define RESPONSE_SCRIPT_FAILED    13
+
+/* Background process function */
+static void down_root_server (const int fd, char *command, const char *argv[], const char *envp[], const int verb);
+
+/*
+ * Plugin state, used by foreground
+ */
+struct down_root_context
+{
+  /* Foreground's socket to background process */
+  int foreground_fd;
+
+  /* Process ID of background process */
+  pid_t background_pid;
+
+  /* Verbosity level of OpenVPN */
+  int verb;
+
+  /* down command */
+  char *command;
+};
+
+/*
+ * Given an environmental variable name, search
+ * the envp array for its value, returning it
+ * if found or NULL otherwise.
+ */
+static const char *
+get_env (const char *name, const char *envp[])
+{
+  if (envp)
+    {
+      int i;
+      const int namelen = strlen (name);
+      for (i = 0; envp[i]; ++i)
+	{
+	  if (!strncmp (envp[i], name, namelen))
+	    {
+	      const char *cp = envp[i] + namelen;
+	      if (*cp == '=')
+		return cp + 1;
+	    }
+	}
+    }
+  return NULL;
+}
+
+/*
+ * Return the length of a string array
+ */
+static int
+string_array_len (const char *array[])
+{
+  int i = 0;
+  if (array)
+    {
+      while (array[i])
+	++i;
+    }
+  return i;
+}
+
+/*
+ * Socket read/write functions.
+ */
+
+static int
+recv_control (int fd)
+{
+  unsigned char c;
+  const ssize_t size = read (fd, &c, sizeof (c));
+  if (size == sizeof (c))
+    return c;
+  else
+    return -1;
+}
+
+static int
+send_control (int fd, int code)
+{
+  unsigned char c = (unsigned char) code;
+  const ssize_t size = write (fd, &c, sizeof (c));
+  if (size == sizeof (c))
+    return (int) size;
+  else
+    return -1;
+}
+
+/*
+ * Daemonize if "daemon" env var is true.
+ * Preserve stderr across daemonization if
+ * "daemon_log_redirect" env var is true.
+ */
+static void
+daemonize (const char *envp[])
+{
+  const char *daemon_string = get_env ("daemon", envp);
+  if (daemon_string && daemon_string[0] == '1')
+    {
+      const char *log_redirect = get_env ("daemon_log_redirect", envp);
+      int fd = -1;
+      if (log_redirect && log_redirect[0] == '1')
+	fd = dup (2);
+      if (daemon (0, 0) < 0)
+	{
+	  fprintf (stderr, "DOWN-ROOT: daemonization failed\n");
+	}
+      else if (fd >= 3)
+	{
+	  dup2 (fd, 2);
+	  close (fd);
+	}
+    }
+}
+
+/*
+ * Close most of parent's fds.
+ * Keep stdin/stdout/stderr, plus one
+ * other fd which is presumed to be
+ * our pipe back to parent.
+ * Admittedly, a bit of a kludge,
+ * but posix doesn't give us a kind
+ * of FD_CLOEXEC which will stop
+ * fds from crossing a fork().
+ */
+static void
+close_fds_except (int keep)
+{
+  int i;
+  closelog ();
+  for (i = 3; i <= 100; ++i)
+    {
+      if (i != keep)
+	close (i);
+    }
+}
+
+/*
+ * Usually we ignore signals, because our parent will
+ * deal with them.
+ */
+static void
+set_signals (void)
+{
+  signal (SIGTERM, SIG_DFL);
+
+  signal (SIGINT, SIG_IGN);
+  signal (SIGHUP, SIG_IGN);
+  signal (SIGUSR1, SIG_IGN);
+  signal (SIGUSR2, SIG_IGN);
+  signal (SIGPIPE, SIG_IGN);
+}
+
+/*
+ * convert system() return into a success/failure value
+ */
+int
+system_ok (int stat)
+{
+#ifdef WIN32
+  return stat == 0;
+#else
+  return stat != -1 && WIFEXITED (stat) && WEXITSTATUS (stat) == 0;
+#endif
+}
+
+static char *
+build_command_line (const char *argv[])
+{
+  int size = 0;
+  int n = 0;
+  int i;
+  char *string;
+
+  /* precompute size */
+  if (argv)
+    {
+      for (i = 0; argv[i]; ++i)
+	{
+	  size += (strlen (argv[i]) + 1); /* string length plus trailing space */
+	  ++n;
+	}
+    }
+  ++size;                                 /* for null terminator */
+
+  /* allocate memory */
+  string = (char *) malloc (size);
+  if (!string)
+    {
+      fprintf (stderr, "DOWN-ROOT: out of memory\n");
+      exit (1);
+    }
+  string[0] = '\0';
+
+  /* build string */
+  for (i = 0; i < n; ++i)
+    {
+      strcat (string, argv[i]);
+      if (i + 1 < n)
+	strcat (string, " ");
+    }
+  return string;
+}
+
+static void
+free_context (struct down_root_context *context)
+{
+  if (context)
+    {
+      if (context->command)
+	free (context->command);
+      free (context);
+    }
+}
+
+OPENVPN_EXPORT openvpn_plugin_handle_t
+openvpn_plugin_open_v1 (unsigned int *type_mask, const char *argv[], const char *envp[])
+{
+  struct down_root_context *context;
+
+  /*
+   * Allocate our context
+   */
+  context = (struct down_root_context *) calloc (1, sizeof (struct down_root_context));
+  if (!context)
+    goto error;
+  context->foreground_fd = -1;
+
+  /*
+   * Intercept the --up and --down callbacks
+   */
+  *type_mask = OPENVPN_PLUGIN_MASK (OPENVPN_PLUGIN_UP) | OPENVPN_PLUGIN_MASK (OPENVPN_PLUGIN_DOWN);
+
+  /*
+   * Make sure we have two string arguments: the first is the .so name,
+   * the second is the script command.
+   */
+  if (string_array_len (argv) < 2)
+    {
+      fprintf (stderr, "DOWN-ROOT: need down script command\n");
+      goto error;
+    }
+
+  /*
+   * Save our argument in context
+   */
+  context->command = build_command_line (&argv[1]);
+
+  /*
+   * Get verbosity level from environment
+   */
+  {
+    const char *verb_string = get_env ("verb", envp);
+    if (verb_string)
+      context->verb = atoi (verb_string);
+  }
+
+  return (openvpn_plugin_handle_t) context;
+
+ error:
+  free_context (context);
+  return NULL;
+}
+
+OPENVPN_EXPORT int
+openvpn_plugin_func_v1 (openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[])
+{
+  struct down_root_context *context = (struct down_root_context *) handle;
+
+  if (type == OPENVPN_PLUGIN_UP && context->foreground_fd == -1) /* fork off a process to hold onto root */
+    {
+      pid_t pid;
+      int fd[2];
+
+      /*
+       * Make a socket for foreground and background processes
+       * to communicate.
+       */
+      if (socketpair (PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
+	{
+	  fprintf (stderr, "DOWN-ROOT: socketpair call failed\n");
+	  return OPENVPN_PLUGIN_FUNC_ERROR;
+	}
+
+      /*
+       * Fork off the privileged process.  It will remain privileged
+       * even after the foreground process drops its privileges.
+       */
+      pid = fork ();
+
+      if (pid)
+	{
+	  int status;
+
+	  /*
+	   * Foreground Process
+	   */
+
+	  context->background_pid = pid;
+
+	  /* close our copy of child's socket */
+	  close (fd[1]);
+
+	  /* don't let future subprocesses inherit child socket */
+	  if (fcntl (fd[0], F_SETFD, FD_CLOEXEC) < 0)
+	    fprintf (stderr, "DOWN-ROOT: Set FD_CLOEXEC flag on socket file descriptor failed\n");
+
+	  /* wait for background child process to initialize */
+	  status = recv_control (fd[0]);
+	  if (status == RESPONSE_INIT_SUCCEEDED)
+	    {
+	      context->foreground_fd = fd[0];
+	      return OPENVPN_PLUGIN_FUNC_SUCCESS;
+	    }
+	}
+      else
+	{
+	  /*
+	   * Background Process
+	   */
+
+	  /* close all parent fds except our socket back to parent */
+	  close_fds_except (fd[1]);
+
+	  /* Ignore most signals (the parent will receive them) */
+	  set_signals ();
+
+	  /* Daemonize if --daemon option is set. */
+	  daemonize (envp);
+
+	  /* execute the event loop */
+	  down_root_server (fd[1], context->command, argv, envp, context->verb);
+
+	  close (fd[1]);
+	  exit (0);
+	  return 0; /* NOTREACHED */
+	}
+    }
+  else if (type == OPENVPN_PLUGIN_DOWN && context->foreground_fd >= 0)
+    {
+      if (send_control (context->foreground_fd, COMMAND_RUN_SCRIPT) == -1)
+	{
+	  fprintf (stderr, "DOWN-ROOT: Error sending script execution signal to background process\n");
+	}
+      else
+	{
+	  const int status = recv_control (context->foreground_fd);
+	  if (status == RESPONSE_SCRIPT_SUCCEEDED)
+	    return OPENVPN_PLUGIN_FUNC_SUCCESS;
+	  if (status == -1)
+	    fprintf (stderr, "DOWN-ROOT: Error receiving script execution confirmation from background process\n");
+	}
+    }
+  return OPENVPN_PLUGIN_FUNC_ERROR;
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_close_v1 (openvpn_plugin_handle_t handle)
+{
+  struct down_root_context *context = (struct down_root_context *) handle;
+
+  if (DEBUG (context->verb))
+    fprintf (stderr, "DOWN-ROOT: close\n");
+
+  if (context->foreground_fd >= 0)
+    {
+      /* tell background process to exit */
+      if (send_control (context->foreground_fd, COMMAND_EXIT) == -1)
+	fprintf (stderr, "DOWN-ROOT: Error signaling background process to exit\n");
+
+      /* wait for background process to exit */
+      if (context->background_pid > 0)
+	waitpid (context->background_pid, NULL, 0);
+
+      close (context->foreground_fd);
+      context->foreground_fd = -1;
+    }
+
+  free_context (context);
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_abort_v1 (openvpn_plugin_handle_t handle)
+{
+  struct down_root_context *context = (struct down_root_context *) handle;
+
+  if (context && context->foreground_fd >= 0)
+    {
+      /* tell background process to exit */
+      send_control (context->foreground_fd, COMMAND_EXIT);
+      close (context->foreground_fd);
+      context->foreground_fd = -1;
+    }
+}
+
+/*
+ * Background process -- runs with privilege.
+ */
+static void
+down_root_server (const int fd, char *command, const char *argv[], const char *envp[], const int verb)
+{
+  const char *p[3];
+  char *command_line = NULL;
+  char *argv_cat = NULL;
+  int i;
+
+  /*
+   * Do initialization
+   */
+  if (DEBUG (verb))
+    fprintf (stderr, "DOWN-ROOT: BACKGROUND: INIT command='%s'\n", command);
+
+  /*
+   * Tell foreground that we initialized successfully
+   */
+  if (send_control (fd, RESPONSE_INIT_SUCCEEDED) == -1)
+    {
+      fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [1]\n");
+      goto done;
+    }
+
+  /*
+   * Build command line
+   */
+  if (string_array_len (argv) >= 2)
+    argv_cat = build_command_line (&argv[1]);
+  else
+    argv_cat = build_command_line (NULL);
+  p[0] = command;
+  p[1] = argv_cat;
+  p[2] = NULL;
+  command_line = build_command_line (p);
+
+  /*
+   * Save envp in environment
+   */
+  for (i = 0; envp[i]; ++i)
+    {
+      putenv ((char *)envp[i]);
+    }
+
+  /*
+   * Event loop
+   */
+  while (1)
+    {
+      int command_code;
+      int status;
+
+      /* get a command from foreground process */
+      command_code = recv_control (fd);
+
+      if (DEBUG (verb))
+	fprintf (stderr, "DOWN-ROOT: BACKGROUND: received command code: %d\n", command_code);
+
+      switch (command_code)
+	{
+	case COMMAND_RUN_SCRIPT:
+	  status = system (command_line);
+	  if (system_ok (status)) /* Succeeded */
+	    {
+	      if (send_control (fd, RESPONSE_SCRIPT_SUCCEEDED) == -1)
+		{
+		  fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [2]\n");
+		  goto done;
+		}
+	    }
+	  else /* Failed */
+	    {
+	      if (send_control (fd, RESPONSE_SCRIPT_FAILED) == -1)
+		{
+		  fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [3]\n");
+		  goto done;
+		}
+	    }
+	  break;
+
+	case COMMAND_EXIT:
+	  goto done;
+
+	case -1:
+	  fprintf (stderr, "DOWN-ROOT: BACKGROUND: read error on command channel\n");
+	  goto done;
+
+	default:
+	  fprintf (stderr, "DOWN-ROOT: BACKGROUND: unknown command code: code=%d, exiting\n",
+		   command_code);
+	  goto done;
+	}
+    }
+
+ done:
+  if (argv_cat)
+    free (argv_cat);
+  if (command_line)
+    free (command_line);
+  if (DEBUG (verb))
+    fprintf (stderr, "DOWN-ROOT: BACKGROUND: EXIT\n");
+
+  return;
+}