diff options
| author | David M. Lee <dlee@digium.com> | 2013-12-16 19:11:51 +0000 |
|---|---|---|
| committer | David M. Lee <dlee@digium.com> | 2013-12-16 19:11:51 +0000 |
| commit | 744556c01d6e28d4ae46c347f77edfb71778d924 (patch) | |
| tree | bc90f83b4ec9ef0eafb3d952076bf9ea24406366 /funcs/func_shell.c | |
| parent | 00dcee2a640394ac0aae294396d96985c6c1aba1 (diff) | |
security: Inhibit execution of privilege escalating functions
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/
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Merged revisions 403913 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 403917 from http://svn.asterisk.org/svn/asterisk/branches/11
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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
Diffstat (limited to 'funcs/func_shell.c')
| -rw-r--r-- | funcs/func_shell.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/funcs/func_shell.c b/funcs/func_shell.c index bad10b381..e403efc2e 100644 --- a/funcs/func_shell.c +++ b/funcs/func_shell.c @@ -88,11 +88,17 @@ static int shell_helper(struct ast_channel *chan, const char *cmd, char *data, </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></note> + <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> @@ -109,7 +115,7 @@ static int unload_module(void) static int load_module(void) { - return ast_custom_function_register(&shell_function); + 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"); |