744556c01d
This patch allows individual dialplan functions to be marked as 'dangerous', to inhibit their execution from external sources. A 'dangerous' function is one which results in a privilege escalation. For example, if one were to read the channel variable SHELL(rm -rf /) Bad Things(TM) could happen; even if the external source has only read permissions. Execution from external sources may be enabled by setting 'live_dangerously' to 'yes' in the [options] section of asterisk.conf. Although doing so is not recommended. Also, the ABI was changed to something more reasonable, since Asterisk 12 does not yet have a public release. (closes issue ASTERISK-22905) Review: http://reviewboard.digium.internal/r/432/ ........ Merged revisions 403913 from http://svn.asterisk.org/svn/asterisk/branches/1.8 ........ Merged revisions 403917 from http://svn.asterisk.org/svn/asterisk/branches/11 ........ Merged revisions 403959 from http://svn.asterisk.org/svn/asterisk/branches/12 git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@403960 65c4cc65-6c06-0410-ace0-fbb531ad65f3
122 lines
3.2 KiB
C
122 lines
3.2 KiB
C
/*
|
|
* Asterisk -- An open source telephony toolkit.
|
|
*
|
|
* Copyright (C) 2006-2012, Digium, Inc.
|
|
*
|
|
* See http://www.asterisk.org for more information about
|
|
* the Asterisk project. Please do not directly contact
|
|
* any of the maintainers of this project for assistance;
|
|
* the project provides a web site, mailing lists and IRC
|
|
* channels for your use.
|
|
*
|
|
* This program is free software, distributed under the terms of
|
|
* the GNU General Public License Version 2. See the LICENSE file
|
|
* at the top of the source tree.
|
|
*/
|
|
|
|
/*! \file
|
|
*
|
|
* SHELL function to return the output generated by a command issued to the system shell.
|
|
*
|
|
* \note Inspiration and Guidance from Russell! Thank You!
|
|
*
|
|
* \author Brandon Kruse <bkruse@digium.com>
|
|
*
|
|
* \ingroup functions
|
|
*/
|
|
|
|
/*** MODULEINFO
|
|
<support_level>core</support_level>
|
|
***/
|
|
|
|
#include "asterisk.h"
|
|
|
|
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
|
|
|
|
#include "asterisk/module.h"
|
|
#include "asterisk/channel.h"
|
|
#include "asterisk/pbx.h"
|
|
#include "asterisk/utils.h"
|
|
#include "asterisk/app.h"
|
|
|
|
static int shell_helper(struct ast_channel *chan, const char *cmd, char *data,
|
|
char *buf, size_t len)
|
|
{
|
|
int res = 0;
|
|
|
|
if (ast_strlen_zero(data)) {
|
|
ast_log(LOG_WARNING, "Missing Argument! Example: Set(foo=${SHELL(echo \"bar\")})\n");
|
|
return -1;
|
|
}
|
|
|
|
if (chan) {
|
|
ast_autoservice_start(chan);
|
|
}
|
|
|
|
if (len >= 1) {
|
|
FILE *ptr;
|
|
char plbuff[4096];
|
|
|
|
ptr = popen(data, "r");
|
|
if (ptr) {
|
|
while (fgets(plbuff, sizeof(plbuff), ptr)) {
|
|
strncat(buf, plbuff, len - strlen(buf) - 1);
|
|
}
|
|
pclose(ptr);
|
|
} else {
|
|
ast_log(LOG_WARNING, "Failed to execute shell command '%s'\n", data);
|
|
res = -1;
|
|
}
|
|
}
|
|
|
|
if (chan) {
|
|
ast_autoservice_stop(chan);
|
|
}
|
|
|
|
return res;
|
|
}
|
|
|
|
/*** DOCUMENTATION
|
|
<function name="SHELL" language="en_US">
|
|
<synopsis>
|
|
Executes a command using the system shell and captures its output.
|
|
</synopsis>
|
|
<syntax>
|
|
<parameter name="command" required="true">
|
|
<para>The command that the shell should execute.</para>
|
|
</parameter>
|
|
</syntax>
|
|
<description>
|
|
<para>Collects the output generated by a command executed by the system shell</para>
|
|
<para>Example: <literal>Set(foo=${SHELL(echo bar)})</literal></para>
|
|
<note>
|
|
<para>The command supplied to this function will be executed by the
|
|
system's shell, typically specified in the SHELL environment variable. There
|
|
are many different system shells available with somewhat different behaviors,
|
|
so the output generated by this function may vary between platforms.</para>
|
|
|
|
<para>If <literal>live_dangerously</literal> in <literal>asterisk.conf</literal>
|
|
is set to <literal>no</literal>, this function can only be executed from the
|
|
dialplan, and not directly from external protocols.</para>
|
|
</note>
|
|
</description>
|
|
|
|
</function>
|
|
***/
|
|
static struct ast_custom_function shell_function = {
|
|
.name = "SHELL",
|
|
.read = shell_helper,
|
|
};
|
|
|
|
static int unload_module(void)
|
|
{
|
|
return ast_custom_function_unregister(&shell_function);
|
|
}
|
|
|
|
static int load_module(void)
|
|
{
|
|
return ast_custom_function_register_escalating(&shell_function, AST_CFE_READ);
|
|
}
|
|
|
|
AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Collects the output generated by a command executed by the system shell");
|