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-rw-r--r--src/plugins/down-root/down-root.c553
1 files changed, 553 insertions, 0 deletions
diff --git a/src/plugins/down-root/down-root.c b/src/plugins/down-root/down-root.c
new file mode 100644
index 0000000..fced23b
--- /dev/null
+++ b/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;
+}
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