New upstream version 2.5~beta1upstream/2.5_beta1

1 files changed, 288 insertions, 0 deletions

diff --git a/src/openvpn/run_command.c b/src/openvpn/run_command.c
new file mode 100644
index 0000000..4c4adf9
--- /dev/null
+++ b/src/openvpn/run_command.c
@@ -0,0 +1,288 @@
+/*
+ *  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) 2002-2017 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; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "platform.h"
+#include "win32.h"
+
+#include "memdbg.h"
+
+#include "run_command.h"
+
+/* contains an SSEC_x value defined in platform.h */
+static int script_security_level = SSEC_BUILT_IN; /* GLOBAL */
+
+int
+script_security(void)
+{
+    return script_security_level;
+}
+
+void
+script_security_set(int level)
+{
+    script_security_level = level;
+}
+
+/*
+ * Generate an error message based on the status code returned by openvpn_execve().
+ */
+static const char *
+system_error_message(int stat, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    switch (stat)
+    {
+        case OPENVPN_EXECVE_NOT_ALLOWED:
+            buf_printf(&out, "disallowed by script-security setting");
+            break;
+
+#ifdef _WIN32
+        case OPENVPN_EXECVE_ERROR:
+            buf_printf(&out, "external program did not execute -- ");
+        /* fall through */
+
+        default:
+            buf_printf(&out, "returned error code %d", stat);
+            break;
+#else  /* ifdef _WIN32 */
+
+        case OPENVPN_EXECVE_ERROR:
+            buf_printf(&out, "external program fork failed");
+            break;
+
+        default:
+            if (!WIFEXITED(stat))
+            {
+                buf_printf(&out, "external program did not exit normally");
+            }
+            else
+            {
+                const int cmd_ret = WEXITSTATUS(stat);
+                if (!cmd_ret)
+                {
+                    buf_printf(&out, "external program exited normally");
+                }
+                else if (cmd_ret == OPENVPN_EXECVE_FAILURE)
+                {
+                    buf_printf(&out, "could not execute external program");
+                }
+                else
+                {
+                    buf_printf(&out, "external program exited with error status: %d", cmd_ret);
+                }
+            }
+            break;
+#endif /* ifdef _WIN32 */
+    }
+    return (const char *)out.data;
+}
+
+bool
+openvpn_execve_allowed(const unsigned int flags)
+{
+    if (flags & S_SCRIPT)
+    {
+        return script_security() >= SSEC_SCRIPTS;
+    }
+    else
+    {
+        return script_security() >= SSEC_BUILT_IN;
+    }
+}
+
+
+#ifndef _WIN32
+/*
+ * Run execve() inside a fork().  Designed to replicate the semantics of system() but
+ * in a safer way that doesn't require the invocation of a shell or the risks
+ * associated with formatting and parsing a command line.
+ * Returns the exit status of child, OPENVPN_EXECVE_NOT_ALLOWED if openvpn_execve_allowed()
+ * returns false, or OPENVPN_EXECVE_ERROR on other errors.
+ */
+int
+openvpn_execve(const struct argv *a, const struct env_set *es, const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    int ret = OPENVPN_EXECVE_ERROR;
+    static bool warn_shown = false;
+
+    if (a && a->argv[0])
+    {
+#if defined(ENABLE_FEATURE_EXECVE)
+        if (openvpn_execve_allowed(flags))
+        {
+            const char *cmd = a->argv[0];
+            char *const *argv = a->argv;
+            char *const *envp = (char *const *)make_env_array(es, true, &gc);
+            pid_t pid;
+
+            pid = fork();
+            if (pid == (pid_t)0) /* child side */
+            {
+                execve(cmd, argv, envp);
+                exit(OPENVPN_EXECVE_FAILURE);
+            }
+            else if (pid < (pid_t)0) /* fork failed */
+            {
+                msg(M_ERR, "openvpn_execve: unable to fork");
+            }
+            else /* parent side */
+            {
+                if (waitpid(pid, &ret, 0) != pid)
+                {
+                    ret = OPENVPN_EXECVE_ERROR;
+                }
+            }
+        }
+        else
+        {
+            ret = OPENVPN_EXECVE_NOT_ALLOWED;
+            if (!warn_shown && (script_security() < SSEC_SCRIPTS))
+            {
+                msg(M_WARN, SCRIPT_SECURITY_WARNING);
+                warn_shown = true;
+            }
+        }
+#else  /* if defined(ENABLE_FEATURE_EXECVE) */
+        msg(M_WARN, "openvpn_execve: execve function not available");
+#endif /* if defined(ENABLE_FEATURE_EXECVE) */
+    }
+    else
+    {
+        msg(M_FATAL, "openvpn_execve: called with empty argv");
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+#endif /* ifndef _WIN32 */
+
+/*
+ * Wrapper around openvpn_execve
+ */
+bool
+openvpn_execve_check(const struct argv *a, const struct env_set *es, const unsigned int flags, const char *error_message)
+{
+    struct gc_arena gc = gc_new();
+    const int stat = openvpn_execve(a, es, flags);
+    int ret = false;
+
+    if (platform_system_ok(stat))
+    {
+        ret = true;
+    }
+    else
+    {
+        if (error_message)
+        {
+            msg(((flags & S_FATAL) ? M_FATAL : M_WARN), "%s: %s",
+                error_message,
+                system_error_message(stat, &gc));
+        }
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Run execve() inside a fork(), duping stdout.  Designed to replicate the semantics of popen() but
+ * in a safer way that doesn't require the invocation of a shell or the risks
+ * associated with formatting and parsing a command line.
+ */
+int
+openvpn_popen(const struct argv *a,  const struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    int ret = -1;
+    static bool warn_shown = false;
+
+    if (a && a->argv[0])
+    {
+#if defined(ENABLE_FEATURE_EXECVE)
+        if (script_security() >= SSEC_BUILT_IN)
+        {
+            const char *cmd = a->argv[0];
+            char *const *argv = a->argv;
+            char *const *envp = (char *const *)make_env_array(es, true, &gc);
+            pid_t pid;
+            int pipe_stdout[2];
+
+            if (pipe(pipe_stdout) == 0)
+            {
+                pid = fork();
+                if (pid == (pid_t)0)       /* child side */
+                {
+                    close(pipe_stdout[0]);         /* Close read end */
+                    dup2(pipe_stdout[1],1);
+                    execve(cmd, argv, envp);
+                    exit(OPENVPN_EXECVE_FAILURE);
+                }
+                else if (pid > (pid_t)0)       /* parent side */
+                {
+                    int status = 0;
+
+                    close(pipe_stdout[1]);        /* Close write end */
+                    waitpid(pid, &status, 0);
+                    ret = pipe_stdout[0];
+                }
+                else       /* fork failed */
+                {
+                    close(pipe_stdout[0]);
+                    close(pipe_stdout[1]);
+                    msg(M_ERR, "openvpn_popen: unable to fork %s", cmd);
+                }
+            }
+            else
+            {
+                msg(M_WARN, "openvpn_popen: unable to create stdout pipe for %s", cmd);
+                ret = -1;
+            }
+        }
+        else if (!warn_shown && (script_security() < SSEC_SCRIPTS))
+        {
+            msg(M_WARN, SCRIPT_SECURITY_WARNING);
+            warn_shown = true;
+        }
+#else  /* if defined(ENABLE_FEATURE_EXECVE) */
+        msg(M_WARN, "openvpn_popen: execve function not available");
+#endif /* if defined(ENABLE_FEATURE_EXECVE) */
+    }
+    else
+    {
+        msg(M_FATAL, "openvpn_popen: called with empty argv");
+    }
+
+    gc_free(&gc);
+    return ret;
+}